Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1 | /* |
| 2 | * random.c -- A strong random number generator |
| 3 | * |
| 4 | * Copyright (C) 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All |
| 5 | * Rights Reserved. |
| 6 | * |
| 7 | * Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005 |
| 8 | * |
| 9 | * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All |
| 10 | * rights reserved. |
| 11 | * |
| 12 | * Redistribution and use in source and binary forms, with or without |
| 13 | * modification, are permitted provided that the following conditions |
| 14 | * are met: |
| 15 | * 1. Redistributions of source code must retain the above copyright |
| 16 | * notice, and the entire permission notice in its entirety, |
| 17 | * including the disclaimer of warranties. |
| 18 | * 2. Redistributions in binary form must reproduce the above copyright |
| 19 | * notice, this list of conditions and the following disclaimer in the |
| 20 | * documentation and/or other materials provided with the distribution. |
| 21 | * 3. The name of the author may not be used to endorse or promote |
| 22 | * products derived from this software without specific prior |
| 23 | * written permission. |
| 24 | * |
| 25 | * ALTERNATIVELY, this product may be distributed under the terms of |
| 26 | * the GNU General Public License, in which case the provisions of the GPL are |
| 27 | * required INSTEAD OF the above restrictions. (This clause is |
| 28 | * necessary due to a potential bad interaction between the GPL and |
| 29 | * the restrictions contained in a BSD-style copyright.) |
| 30 | * |
| 31 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| 32 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 33 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF |
| 34 | * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE |
| 35 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 36 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT |
| 37 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR |
| 38 | * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| 39 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 40 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE |
| 41 | * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH |
| 42 | * DAMAGE. |
| 43 | */ |
| 44 | |
| 45 | /* |
| 46 | * (now, with legal B.S. out of the way.....) |
| 47 | * |
| 48 | * This routine gathers environmental noise from device drivers, etc., |
| 49 | * and returns good random numbers, suitable for cryptographic use. |
| 50 | * Besides the obvious cryptographic uses, these numbers are also good |
| 51 | * for seeding TCP sequence numbers, and other places where it is |
| 52 | * desirable to have numbers which are not only random, but hard to |
| 53 | * predict by an attacker. |
| 54 | * |
| 55 | * Theory of operation |
| 56 | * =================== |
| 57 | * |
| 58 | * Computers are very predictable devices. Hence it is extremely hard |
| 59 | * to produce truly random numbers on a computer --- as opposed to |
| 60 | * pseudo-random numbers, which can easily generated by using a |
| 61 | * algorithm. Unfortunately, it is very easy for attackers to guess |
| 62 | * the sequence of pseudo-random number generators, and for some |
| 63 | * applications this is not acceptable. So instead, we must try to |
| 64 | * gather "environmental noise" from the computer's environment, which |
| 65 | * must be hard for outside attackers to observe, and use that to |
| 66 | * generate random numbers. In a Unix environment, this is best done |
| 67 | * from inside the kernel. |
| 68 | * |
| 69 | * Sources of randomness from the environment include inter-keyboard |
| 70 | * timings, inter-interrupt timings from some interrupts, and other |
| 71 | * events which are both (a) non-deterministic and (b) hard for an |
| 72 | * outside observer to measure. Randomness from these sources are |
| 73 | * added to an "entropy pool", which is mixed using a CRC-like function. |
| 74 | * This is not cryptographically strong, but it is adequate assuming |
| 75 | * the randomness is not chosen maliciously, and it is fast enough that |
| 76 | * the overhead of doing it on every interrupt is very reasonable. |
| 77 | * As random bytes are mixed into the entropy pool, the routines keep |
| 78 | * an *estimate* of how many bits of randomness have been stored into |
| 79 | * the random number generator's internal state. |
| 80 | * |
| 81 | * When random bytes are desired, they are obtained by taking the SHA |
| 82 | * hash of the contents of the "entropy pool". The SHA hash avoids |
| 83 | * exposing the internal state of the entropy pool. It is believed to |
| 84 | * be computationally infeasible to derive any useful information |
| 85 | * about the input of SHA from its output. Even if it is possible to |
| 86 | * analyze SHA in some clever way, as long as the amount of data |
| 87 | * returned from the generator is less than the inherent entropy in |
| 88 | * the pool, the output data is totally unpredictable. For this |
| 89 | * reason, the routine decreases its internal estimate of how many |
| 90 | * bits of "true randomness" are contained in the entropy pool as it |
| 91 | * outputs random numbers. |
| 92 | * |
| 93 | * If this estimate goes to zero, the routine can still generate |
| 94 | * random numbers; however, an attacker may (at least in theory) be |
| 95 | * able to infer the future output of the generator from prior |
| 96 | * outputs. This requires successful cryptanalysis of SHA, which is |
| 97 | * not believed to be feasible, but there is a remote possibility. |
| 98 | * Nonetheless, these numbers should be useful for the vast majority |
| 99 | * of purposes. |
| 100 | * |
| 101 | * Exported interfaces ---- output |
| 102 | * =============================== |
| 103 | * |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 104 | * There are four exported interfaces; two for use within the kernel, |
| 105 | * and two or use from userspace. |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 106 | * |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 107 | * Exported interfaces ---- userspace output |
| 108 | * ----------------------------------------- |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 109 | * |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 110 | * The userspace interfaces are two character devices /dev/random and |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 111 | * /dev/urandom. /dev/random is suitable for use when very high |
| 112 | * quality randomness is desired (for example, for key generation or |
| 113 | * one-time pads), as it will only return a maximum of the number of |
| 114 | * bits of randomness (as estimated by the random number generator) |
| 115 | * contained in the entropy pool. |
| 116 | * |
| 117 | * The /dev/urandom device does not have this limit, and will return |
| 118 | * as many bytes as are requested. As more and more random bytes are |
| 119 | * requested without giving time for the entropy pool to recharge, |
| 120 | * this will result in random numbers that are merely cryptographically |
| 121 | * strong. For many applications, however, this is acceptable. |
| 122 | * |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 123 | * Exported interfaces ---- kernel output |
| 124 | * -------------------------------------- |
| 125 | * |
| 126 | * The primary kernel interface is |
| 127 | * |
| 128 | * void get_random_bytes(void *buf, int nbytes); |
| 129 | * |
| 130 | * This interface will return the requested number of random bytes, |
| 131 | * and place it in the requested buffer. This is equivalent to a |
| 132 | * read from /dev/urandom. |
| 133 | * |
| 134 | * For less critical applications, there are the functions: |
| 135 | * |
| 136 | * u32 get_random_u32() |
| 137 | * u64 get_random_u64() |
| 138 | * unsigned int get_random_int() |
| 139 | * unsigned long get_random_long() |
| 140 | * |
| 141 | * These are produced by a cryptographic RNG seeded from get_random_bytes, |
| 142 | * and so do not deplete the entropy pool as much. These are recommended |
| 143 | * for most in-kernel operations *if the result is going to be stored in |
| 144 | * the kernel*. |
| 145 | * |
| 146 | * Specifically, the get_random_int() family do not attempt to do |
| 147 | * "anti-backtracking". If you capture the state of the kernel (e.g. |
| 148 | * by snapshotting the VM), you can figure out previous get_random_int() |
| 149 | * return values. But if the value is stored in the kernel anyway, |
| 150 | * this is not a problem. |
| 151 | * |
| 152 | * It *is* safe to expose get_random_int() output to attackers (e.g. as |
| 153 | * network cookies); given outputs 1..n, it's not feasible to predict |
| 154 | * outputs 0 or n+1. The only concern is an attacker who breaks into |
| 155 | * the kernel later; the get_random_int() engine is not reseeded as |
| 156 | * often as the get_random_bytes() one. |
| 157 | * |
| 158 | * get_random_bytes() is needed for keys that need to stay secret after |
| 159 | * they are erased from the kernel. For example, any key that will |
| 160 | * be wrapped and stored encrypted. And session encryption keys: we'd |
| 161 | * like to know that after the session is closed and the keys erased, |
| 162 | * the plaintext is unrecoverable to someone who recorded the ciphertext. |
| 163 | * |
| 164 | * But for network ports/cookies, stack canaries, PRNG seeds, address |
| 165 | * space layout randomization, session *authentication* keys, or other |
| 166 | * applications where the sensitive data is stored in the kernel in |
| 167 | * plaintext for as long as it's sensitive, the get_random_int() family |
| 168 | * is just fine. |
| 169 | * |
| 170 | * Consider ASLR. We want to keep the address space secret from an |
| 171 | * outside attacker while the process is running, but once the address |
| 172 | * space is torn down, it's of no use to an attacker any more. And it's |
| 173 | * stored in kernel data structures as long as it's alive, so worrying |
| 174 | * about an attacker's ability to extrapolate it from the get_random_int() |
| 175 | * CRNG is silly. |
| 176 | * |
| 177 | * Even some cryptographic keys are safe to generate with get_random_int(). |
| 178 | * In particular, keys for SipHash are generally fine. Here, knowledge |
| 179 | * of the key authorizes you to do something to a kernel object (inject |
| 180 | * packets to a network connection, or flood a hash table), and the |
| 181 | * key is stored with the object being protected. Once it goes away, |
| 182 | * we no longer care if anyone knows the key. |
| 183 | * |
| 184 | * prandom_u32() |
| 185 | * ------------- |
| 186 | * |
| 187 | * For even weaker applications, see the pseudorandom generator |
| 188 | * prandom_u32(), prandom_max(), and prandom_bytes(). If the random |
| 189 | * numbers aren't security-critical at all, these are *far* cheaper. |
| 190 | * Useful for self-tests, random error simulation, randomized backoffs, |
| 191 | * and any other application where you trust that nobody is trying to |
| 192 | * maliciously mess with you by guessing the "random" numbers. |
| 193 | * |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 194 | * Exported interfaces ---- input |
| 195 | * ============================== |
| 196 | * |
| 197 | * The current exported interfaces for gathering environmental noise |
| 198 | * from the devices are: |
| 199 | * |
| 200 | * void add_device_randomness(const void *buf, unsigned int size); |
| 201 | * void add_input_randomness(unsigned int type, unsigned int code, |
| 202 | * unsigned int value); |
| 203 | * void add_interrupt_randomness(int irq, int irq_flags); |
| 204 | * void add_disk_randomness(struct gendisk *disk); |
| 205 | * |
| 206 | * add_device_randomness() is for adding data to the random pool that |
| 207 | * is likely to differ between two devices (or possibly even per boot). |
| 208 | * This would be things like MAC addresses or serial numbers, or the |
| 209 | * read-out of the RTC. This does *not* add any actual entropy to the |
| 210 | * pool, but it initializes the pool to different values for devices |
| 211 | * that might otherwise be identical and have very little entropy |
| 212 | * available to them (particularly common in the embedded world). |
| 213 | * |
| 214 | * add_input_randomness() uses the input layer interrupt timing, as well as |
| 215 | * the event type information from the hardware. |
| 216 | * |
| 217 | * add_interrupt_randomness() uses the interrupt timing as random |
| 218 | * inputs to the entropy pool. Using the cycle counters and the irq source |
| 219 | * as inputs, it feeds the randomness roughly once a second. |
| 220 | * |
| 221 | * add_disk_randomness() uses what amounts to the seek time of block |
| 222 | * layer request events, on a per-disk_devt basis, as input to the |
| 223 | * entropy pool. Note that high-speed solid state drives with very low |
| 224 | * seek times do not make for good sources of entropy, as their seek |
| 225 | * times are usually fairly consistent. |
| 226 | * |
| 227 | * All of these routines try to estimate how many bits of randomness a |
| 228 | * particular randomness source. They do this by keeping track of the |
| 229 | * first and second order deltas of the event timings. |
| 230 | * |
| 231 | * Ensuring unpredictability at system startup |
| 232 | * ============================================ |
| 233 | * |
| 234 | * When any operating system starts up, it will go through a sequence |
| 235 | * of actions that are fairly predictable by an adversary, especially |
| 236 | * if the start-up does not involve interaction with a human operator. |
| 237 | * This reduces the actual number of bits of unpredictability in the |
| 238 | * entropy pool below the value in entropy_count. In order to |
| 239 | * counteract this effect, it helps to carry information in the |
| 240 | * entropy pool across shut-downs and start-ups. To do this, put the |
| 241 | * following lines an appropriate script which is run during the boot |
| 242 | * sequence: |
| 243 | * |
| 244 | * echo "Initializing random number generator..." |
| 245 | * random_seed=/var/run/random-seed |
| 246 | * # Carry a random seed from start-up to start-up |
| 247 | * # Load and then save the whole entropy pool |
| 248 | * if [ -f $random_seed ]; then |
| 249 | * cat $random_seed >/dev/urandom |
| 250 | * else |
| 251 | * touch $random_seed |
| 252 | * fi |
| 253 | * chmod 600 $random_seed |
| 254 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 |
| 255 | * |
| 256 | * and the following lines in an appropriate script which is run as |
| 257 | * the system is shutdown: |
| 258 | * |
| 259 | * # Carry a random seed from shut-down to start-up |
| 260 | * # Save the whole entropy pool |
| 261 | * echo "Saving random seed..." |
| 262 | * random_seed=/var/run/random-seed |
| 263 | * touch $random_seed |
| 264 | * chmod 600 $random_seed |
| 265 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 |
| 266 | * |
| 267 | * For example, on most modern systems using the System V init |
| 268 | * scripts, such code fragments would be found in |
| 269 | * /etc/rc.d/init.d/random. On older Linux systems, the correct script |
| 270 | * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0. |
| 271 | * |
| 272 | * Effectively, these commands cause the contents of the entropy pool |
| 273 | * to be saved at shut-down time and reloaded into the entropy pool at |
| 274 | * start-up. (The 'dd' in the addition to the bootup script is to |
| 275 | * make sure that /etc/random-seed is different for every start-up, |
| 276 | * even if the system crashes without executing rc.0.) Even with |
| 277 | * complete knowledge of the start-up activities, predicting the state |
| 278 | * of the entropy pool requires knowledge of the previous history of |
| 279 | * the system. |
| 280 | * |
| 281 | * Configuring the /dev/random driver under Linux |
| 282 | * ============================================== |
| 283 | * |
| 284 | * The /dev/random driver under Linux uses minor numbers 8 and 9 of |
| 285 | * the /dev/mem major number (#1). So if your system does not have |
| 286 | * /dev/random and /dev/urandom created already, they can be created |
| 287 | * by using the commands: |
| 288 | * |
| 289 | * mknod /dev/random c 1 8 |
| 290 | * mknod /dev/urandom c 1 9 |
| 291 | * |
| 292 | * Acknowledgements: |
| 293 | * ================= |
| 294 | * |
| 295 | * Ideas for constructing this random number generator were derived |
| 296 | * from Pretty Good Privacy's random number generator, and from private |
| 297 | * discussions with Phil Karn. Colin Plumb provided a faster random |
| 298 | * number generator, which speed up the mixing function of the entropy |
| 299 | * pool, taken from PGPfone. Dale Worley has also contributed many |
| 300 | * useful ideas and suggestions to improve this driver. |
| 301 | * |
| 302 | * Any flaws in the design are solely my responsibility, and should |
| 303 | * not be attributed to the Phil, Colin, or any of authors of PGP. |
| 304 | * |
| 305 | * Further background information on this topic may be obtained from |
| 306 | * RFC 1750, "Randomness Recommendations for Security", by Donald |
| 307 | * Eastlake, Steve Crocker, and Jeff Schiller. |
| 308 | */ |
| 309 | |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 310 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 311 | |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 312 | #include <linux/utsname.h> |
| 313 | #include <linux/module.h> |
| 314 | #include <linux/kernel.h> |
| 315 | #include <linux/major.h> |
| 316 | #include <linux/string.h> |
| 317 | #include <linux/fcntl.h> |
| 318 | #include <linux/slab.h> |
| 319 | #include <linux/random.h> |
| 320 | #include <linux/poll.h> |
| 321 | #include <linux/init.h> |
| 322 | #include <linux/fs.h> |
| 323 | #include <linux/genhd.h> |
| 324 | #include <linux/interrupt.h> |
| 325 | #include <linux/mm.h> |
| 326 | #include <linux/nodemask.h> |
| 327 | #include <linux/spinlock.h> |
| 328 | #include <linux/kthread.h> |
| 329 | #include <linux/percpu.h> |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 330 | #include <linux/fips.h> |
| 331 | #include <linux/ptrace.h> |
| 332 | #include <linux/workqueue.h> |
| 333 | #include <linux/irq.h> |
| 334 | #include <linux/ratelimit.h> |
| 335 | #include <linux/syscalls.h> |
| 336 | #include <linux/completion.h> |
| 337 | #include <linux/uuid.h> |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 338 | #include <crypto/chacha.h> |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 339 | #include <crypto/sha.h> |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 340 | |
| 341 | #include <asm/processor.h> |
| 342 | #include <linux/uaccess.h> |
| 343 | #include <asm/irq.h> |
| 344 | #include <asm/irq_regs.h> |
| 345 | #include <asm/io.h> |
| 346 | |
| 347 | #define CREATE_TRACE_POINTS |
| 348 | #include <trace/events/random.h> |
| 349 | |
| 350 | /* #define ADD_INTERRUPT_BENCH */ |
| 351 | |
| 352 | /* |
| 353 | * Configuration information |
| 354 | */ |
| 355 | #define INPUT_POOL_SHIFT 12 |
| 356 | #define INPUT_POOL_WORDS (1 << (INPUT_POOL_SHIFT-5)) |
| 357 | #define OUTPUT_POOL_SHIFT 10 |
| 358 | #define OUTPUT_POOL_WORDS (1 << (OUTPUT_POOL_SHIFT-5)) |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 359 | #define EXTRACT_SIZE 10 |
| 360 | |
| 361 | |
| 362 | #define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long)) |
| 363 | |
| 364 | /* |
| 365 | * To allow fractional bits to be tracked, the entropy_count field is |
| 366 | * denominated in units of 1/8th bits. |
| 367 | * |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 368 | * 2*(ENTROPY_SHIFT + poolbitshift) must <= 31, or the multiply in |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 369 | * credit_entropy_bits() needs to be 64 bits wide. |
| 370 | */ |
| 371 | #define ENTROPY_SHIFT 3 |
| 372 | #define ENTROPY_BITS(r) ((r)->entropy_count >> ENTROPY_SHIFT) |
| 373 | |
| 374 | /* |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 375 | * If the entropy count falls under this number of bits, then we |
| 376 | * should wake up processes which are selecting or polling on write |
| 377 | * access to /dev/random. |
| 378 | */ |
| 379 | static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS; |
| 380 | |
| 381 | /* |
| 382 | * Originally, we used a primitive polynomial of degree .poolwords |
| 383 | * over GF(2). The taps for various sizes are defined below. They |
| 384 | * were chosen to be evenly spaced except for the last tap, which is 1 |
| 385 | * to get the twisting happening as fast as possible. |
| 386 | * |
| 387 | * For the purposes of better mixing, we use the CRC-32 polynomial as |
| 388 | * well to make a (modified) twisted Generalized Feedback Shift |
| 389 | * Register. (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR |
| 390 | * generators. ACM Transactions on Modeling and Computer Simulation |
| 391 | * 2(3):179-194. Also see M. Matsumoto & Y. Kurita, 1994. Twisted |
| 392 | * GFSR generators II. ACM Transactions on Modeling and Computer |
| 393 | * Simulation 4:254-266) |
| 394 | * |
| 395 | * Thanks to Colin Plumb for suggesting this. |
| 396 | * |
| 397 | * The mixing operation is much less sensitive than the output hash, |
| 398 | * where we use SHA-1. All that we want of mixing operation is that |
| 399 | * it be a good non-cryptographic hash; i.e. it not produce collisions |
| 400 | * when fed "random" data of the sort we expect to see. As long as |
| 401 | * the pool state differs for different inputs, we have preserved the |
| 402 | * input entropy and done a good job. The fact that an intelligent |
| 403 | * attacker can construct inputs that will produce controlled |
| 404 | * alterations to the pool's state is not important because we don't |
| 405 | * consider such inputs to contribute any randomness. The only |
| 406 | * property we need with respect to them is that the attacker can't |
| 407 | * increase his/her knowledge of the pool's state. Since all |
| 408 | * additions are reversible (knowing the final state and the input, |
| 409 | * you can reconstruct the initial state), if an attacker has any |
| 410 | * uncertainty about the initial state, he/she can only shuffle that |
| 411 | * uncertainty about, but never cause any collisions (which would |
| 412 | * decrease the uncertainty). |
| 413 | * |
| 414 | * Our mixing functions were analyzed by Lacharme, Roeck, Strubel, and |
| 415 | * Videau in their paper, "The Linux Pseudorandom Number Generator |
| 416 | * Revisited" (see: http://eprint.iacr.org/2012/251.pdf). In their |
| 417 | * paper, they point out that we are not using a true Twisted GFSR, |
| 418 | * since Matsumoto & Kurita used a trinomial feedback polynomial (that |
| 419 | * is, with only three taps, instead of the six that we are using). |
| 420 | * As a result, the resulting polynomial is neither primitive nor |
| 421 | * irreducible, and hence does not have a maximal period over |
| 422 | * GF(2**32). They suggest a slight change to the generator |
| 423 | * polynomial which improves the resulting TGFSR polynomial to be |
| 424 | * irreducible, which we have made here. |
| 425 | */ |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 426 | static const struct poolinfo { |
| 427 | int poolbitshift, poolwords, poolbytes, poolfracbits; |
| 428 | #define S(x) ilog2(x)+5, (x), (x)*4, (x) << (ENTROPY_SHIFT+5) |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 429 | int tap1, tap2, tap3, tap4, tap5; |
| 430 | } poolinfo_table[] = { |
| 431 | /* was: x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 */ |
| 432 | /* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */ |
| 433 | { S(128), 104, 76, 51, 25, 1 }, |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 434 | }; |
| 435 | |
| 436 | /* |
| 437 | * Static global variables |
| 438 | */ |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 439 | static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); |
| 440 | static struct fasync_struct *fasync; |
| 441 | |
| 442 | static DEFINE_SPINLOCK(random_ready_list_lock); |
| 443 | static LIST_HEAD(random_ready_list); |
| 444 | |
| 445 | struct crng_state { |
| 446 | __u32 state[16]; |
| 447 | unsigned long init_time; |
| 448 | spinlock_t lock; |
| 449 | }; |
| 450 | |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 451 | static struct crng_state primary_crng = { |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 452 | .lock = __SPIN_LOCK_UNLOCKED(primary_crng.lock), |
| 453 | }; |
| 454 | |
| 455 | /* |
| 456 | * crng_init = 0 --> Uninitialized |
| 457 | * 1 --> Initialized |
| 458 | * 2 --> Initialized from input_pool |
| 459 | * |
| 460 | * crng_init is protected by primary_crng->lock, and only increases |
| 461 | * its value (from 0->1->2). |
| 462 | */ |
| 463 | static int crng_init = 0; |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 464 | static bool crng_need_final_init = false; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 465 | #define crng_ready() (likely(crng_init > 1)) |
| 466 | static int crng_init_cnt = 0; |
| 467 | static unsigned long crng_global_init_time = 0; |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 468 | #define CRNG_INIT_CNT_THRESH (2*CHACHA_KEY_SIZE) |
| 469 | static void _extract_crng(struct crng_state *crng, __u8 out[CHACHA_BLOCK_SIZE]); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 470 | static void _crng_backtrack_protect(struct crng_state *crng, |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 471 | __u8 tmp[CHACHA_BLOCK_SIZE], int used); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 472 | static void process_random_ready_list(void); |
| 473 | static void _get_random_bytes(void *buf, int nbytes); |
| 474 | |
| 475 | static struct ratelimit_state unseeded_warning = |
| 476 | RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3); |
| 477 | static struct ratelimit_state urandom_warning = |
| 478 | RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3); |
| 479 | |
| 480 | static int ratelimit_disable __read_mostly; |
| 481 | |
| 482 | module_param_named(ratelimit_disable, ratelimit_disable, int, 0644); |
| 483 | MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression"); |
| 484 | |
| 485 | /********************************************************************** |
| 486 | * |
| 487 | * OS independent entropy store. Here are the functions which handle |
| 488 | * storing entropy in an entropy pool. |
| 489 | * |
| 490 | **********************************************************************/ |
| 491 | |
| 492 | struct entropy_store; |
| 493 | struct entropy_store { |
| 494 | /* read-only data: */ |
| 495 | const struct poolinfo *poolinfo; |
| 496 | __u32 *pool; |
| 497 | const char *name; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 498 | |
| 499 | /* read-write data: */ |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 500 | spinlock_t lock; |
| 501 | unsigned short add_ptr; |
| 502 | unsigned short input_rotate; |
| 503 | int entropy_count; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 504 | unsigned int initialized:1; |
| 505 | unsigned int last_data_init:1; |
| 506 | __u8 last_data[EXTRACT_SIZE]; |
| 507 | }; |
| 508 | |
| 509 | static ssize_t extract_entropy(struct entropy_store *r, void *buf, |
| 510 | size_t nbytes, int min, int rsvd); |
| 511 | static ssize_t _extract_entropy(struct entropy_store *r, void *buf, |
| 512 | size_t nbytes, int fips); |
| 513 | |
| 514 | static void crng_reseed(struct crng_state *crng, struct entropy_store *r); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 515 | static __u32 input_pool_data[INPUT_POOL_WORDS] __latent_entropy; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 516 | |
| 517 | static struct entropy_store input_pool = { |
| 518 | .poolinfo = &poolinfo_table[0], |
| 519 | .name = "input", |
| 520 | .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock), |
| 521 | .pool = input_pool_data |
| 522 | }; |
| 523 | |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 524 | static __u32 const twist_table[8] = { |
| 525 | 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158, |
| 526 | 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 }; |
| 527 | |
| 528 | /* |
| 529 | * This function adds bytes into the entropy "pool". It does not |
| 530 | * update the entropy estimate. The caller should call |
| 531 | * credit_entropy_bits if this is appropriate. |
| 532 | * |
| 533 | * The pool is stirred with a primitive polynomial of the appropriate |
| 534 | * degree, and then twisted. We twist by three bits at a time because |
| 535 | * it's cheap to do so and helps slightly in the expected case where |
| 536 | * the entropy is concentrated in the low-order bits. |
| 537 | */ |
| 538 | static void _mix_pool_bytes(struct entropy_store *r, const void *in, |
| 539 | int nbytes) |
| 540 | { |
| 541 | unsigned long i, tap1, tap2, tap3, tap4, tap5; |
| 542 | int input_rotate; |
| 543 | int wordmask = r->poolinfo->poolwords - 1; |
| 544 | const char *bytes = in; |
| 545 | __u32 w; |
| 546 | |
| 547 | tap1 = r->poolinfo->tap1; |
| 548 | tap2 = r->poolinfo->tap2; |
| 549 | tap3 = r->poolinfo->tap3; |
| 550 | tap4 = r->poolinfo->tap4; |
| 551 | tap5 = r->poolinfo->tap5; |
| 552 | |
| 553 | input_rotate = r->input_rotate; |
| 554 | i = r->add_ptr; |
| 555 | |
| 556 | /* mix one byte at a time to simplify size handling and churn faster */ |
| 557 | while (nbytes--) { |
| 558 | w = rol32(*bytes++, input_rotate); |
| 559 | i = (i - 1) & wordmask; |
| 560 | |
| 561 | /* XOR in the various taps */ |
| 562 | w ^= r->pool[i]; |
| 563 | w ^= r->pool[(i + tap1) & wordmask]; |
| 564 | w ^= r->pool[(i + tap2) & wordmask]; |
| 565 | w ^= r->pool[(i + tap3) & wordmask]; |
| 566 | w ^= r->pool[(i + tap4) & wordmask]; |
| 567 | w ^= r->pool[(i + tap5) & wordmask]; |
| 568 | |
| 569 | /* Mix the result back in with a twist */ |
| 570 | r->pool[i] = (w >> 3) ^ twist_table[w & 7]; |
| 571 | |
| 572 | /* |
| 573 | * Normally, we add 7 bits of rotation to the pool. |
| 574 | * At the beginning of the pool, add an extra 7 bits |
| 575 | * rotation, so that successive passes spread the |
| 576 | * input bits across the pool evenly. |
| 577 | */ |
| 578 | input_rotate = (input_rotate + (i ? 7 : 14)) & 31; |
| 579 | } |
| 580 | |
| 581 | r->input_rotate = input_rotate; |
| 582 | r->add_ptr = i; |
| 583 | } |
| 584 | |
| 585 | static void __mix_pool_bytes(struct entropy_store *r, const void *in, |
| 586 | int nbytes) |
| 587 | { |
| 588 | trace_mix_pool_bytes_nolock(r->name, nbytes, _RET_IP_); |
| 589 | _mix_pool_bytes(r, in, nbytes); |
| 590 | } |
| 591 | |
| 592 | static void mix_pool_bytes(struct entropy_store *r, const void *in, |
| 593 | int nbytes) |
| 594 | { |
| 595 | unsigned long flags; |
| 596 | |
| 597 | trace_mix_pool_bytes(r->name, nbytes, _RET_IP_); |
| 598 | spin_lock_irqsave(&r->lock, flags); |
| 599 | _mix_pool_bytes(r, in, nbytes); |
| 600 | spin_unlock_irqrestore(&r->lock, flags); |
| 601 | } |
| 602 | |
| 603 | struct fast_pool { |
| 604 | __u32 pool[4]; |
| 605 | unsigned long last; |
| 606 | unsigned short reg_idx; |
| 607 | unsigned char count; |
| 608 | }; |
| 609 | |
| 610 | /* |
| 611 | * This is a fast mixing routine used by the interrupt randomness |
| 612 | * collector. It's hardcoded for an 128 bit pool and assumes that any |
| 613 | * locks that might be needed are taken by the caller. |
| 614 | */ |
| 615 | static void fast_mix(struct fast_pool *f) |
| 616 | { |
| 617 | __u32 a = f->pool[0], b = f->pool[1]; |
| 618 | __u32 c = f->pool[2], d = f->pool[3]; |
| 619 | |
| 620 | a += b; c += d; |
| 621 | b = rol32(b, 6); d = rol32(d, 27); |
| 622 | d ^= a; b ^= c; |
| 623 | |
| 624 | a += b; c += d; |
| 625 | b = rol32(b, 16); d = rol32(d, 14); |
| 626 | d ^= a; b ^= c; |
| 627 | |
| 628 | a += b; c += d; |
| 629 | b = rol32(b, 6); d = rol32(d, 27); |
| 630 | d ^= a; b ^= c; |
| 631 | |
| 632 | a += b; c += d; |
| 633 | b = rol32(b, 16); d = rol32(d, 14); |
| 634 | d ^= a; b ^= c; |
| 635 | |
| 636 | f->pool[0] = a; f->pool[1] = b; |
| 637 | f->pool[2] = c; f->pool[3] = d; |
| 638 | f->count++; |
| 639 | } |
| 640 | |
| 641 | static void process_random_ready_list(void) |
| 642 | { |
| 643 | unsigned long flags; |
| 644 | struct random_ready_callback *rdy, *tmp; |
| 645 | |
| 646 | spin_lock_irqsave(&random_ready_list_lock, flags); |
| 647 | list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) { |
| 648 | struct module *owner = rdy->owner; |
| 649 | |
| 650 | list_del_init(&rdy->list); |
| 651 | rdy->func(rdy); |
| 652 | module_put(owner); |
| 653 | } |
| 654 | spin_unlock_irqrestore(&random_ready_list_lock, flags); |
| 655 | } |
| 656 | |
| 657 | /* |
| 658 | * Credit (or debit) the entropy store with n bits of entropy. |
| 659 | * Use credit_entropy_bits_safe() if the value comes from userspace |
| 660 | * or otherwise should be checked for extreme values. |
| 661 | */ |
| 662 | static void credit_entropy_bits(struct entropy_store *r, int nbits) |
| 663 | { |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 664 | int entropy_count, orig, has_initialized = 0; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 665 | const int pool_size = r->poolinfo->poolfracbits; |
| 666 | int nfrac = nbits << ENTROPY_SHIFT; |
| 667 | |
| 668 | if (!nbits) |
| 669 | return; |
| 670 | |
| 671 | retry: |
| 672 | entropy_count = orig = READ_ONCE(r->entropy_count); |
| 673 | if (nfrac < 0) { |
| 674 | /* Debit */ |
| 675 | entropy_count += nfrac; |
| 676 | } else { |
| 677 | /* |
| 678 | * Credit: we have to account for the possibility of |
| 679 | * overwriting already present entropy. Even in the |
| 680 | * ideal case of pure Shannon entropy, new contributions |
| 681 | * approach the full value asymptotically: |
| 682 | * |
| 683 | * entropy <- entropy + (pool_size - entropy) * |
| 684 | * (1 - exp(-add_entropy/pool_size)) |
| 685 | * |
| 686 | * For add_entropy <= pool_size/2 then |
| 687 | * (1 - exp(-add_entropy/pool_size)) >= |
| 688 | * (add_entropy/pool_size)*0.7869... |
| 689 | * so we can approximate the exponential with |
| 690 | * 3/4*add_entropy/pool_size and still be on the |
| 691 | * safe side by adding at most pool_size/2 at a time. |
| 692 | * |
| 693 | * The use of pool_size-2 in the while statement is to |
| 694 | * prevent rounding artifacts from making the loop |
| 695 | * arbitrarily long; this limits the loop to log2(pool_size)*2 |
| 696 | * turns no matter how large nbits is. |
| 697 | */ |
| 698 | int pnfrac = nfrac; |
| 699 | const int s = r->poolinfo->poolbitshift + ENTROPY_SHIFT + 2; |
| 700 | /* The +2 corresponds to the /4 in the denominator */ |
| 701 | |
| 702 | do { |
| 703 | unsigned int anfrac = min(pnfrac, pool_size/2); |
| 704 | unsigned int add = |
| 705 | ((pool_size - entropy_count)*anfrac*3) >> s; |
| 706 | |
| 707 | entropy_count += add; |
| 708 | pnfrac -= anfrac; |
| 709 | } while (unlikely(entropy_count < pool_size-2 && pnfrac)); |
| 710 | } |
| 711 | |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 712 | if (WARN_ON(entropy_count < 0)) { |
| 713 | pr_warn("negative entropy/overflow: pool %s count %d\n", |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 714 | r->name, entropy_count); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 715 | entropy_count = 0; |
| 716 | } else if (entropy_count > pool_size) |
| 717 | entropy_count = pool_size; |
| 718 | if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) |
| 719 | goto retry; |
| 720 | |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 721 | if (has_initialized) { |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 722 | r->initialized = 1; |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 723 | kill_fasync(&fasync, SIGIO, POLL_IN); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 724 | } |
| 725 | |
| 726 | trace_credit_entropy_bits(r->name, nbits, |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 727 | entropy_count >> ENTROPY_SHIFT, _RET_IP_); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 728 | |
| 729 | if (r == &input_pool) { |
| 730 | int entropy_bits = entropy_count >> ENTROPY_SHIFT; |
| 731 | |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 732 | if (crng_init < 2) { |
| 733 | if (entropy_bits < 128) |
| 734 | return; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 735 | crng_reseed(&primary_crng, r); |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 736 | entropy_bits = ENTROPY_BITS(r); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 737 | } |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 738 | } |
| 739 | } |
| 740 | |
| 741 | static int credit_entropy_bits_safe(struct entropy_store *r, int nbits) |
| 742 | { |
| 743 | const int nbits_max = r->poolinfo->poolwords * 32; |
| 744 | |
| 745 | if (nbits < 0) |
| 746 | return -EINVAL; |
| 747 | |
| 748 | /* Cap the value to avoid overflows */ |
| 749 | nbits = min(nbits, nbits_max); |
| 750 | |
| 751 | credit_entropy_bits(r, nbits); |
| 752 | return 0; |
| 753 | } |
| 754 | |
| 755 | /********************************************************************* |
| 756 | * |
| 757 | * CRNG using CHACHA20 |
| 758 | * |
| 759 | *********************************************************************/ |
| 760 | |
| 761 | #define CRNG_RESEED_INTERVAL (300*HZ) |
| 762 | |
| 763 | static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); |
| 764 | |
| 765 | #ifdef CONFIG_NUMA |
| 766 | /* |
| 767 | * Hack to deal with crazy userspace progams when they are all trying |
| 768 | * to access /dev/urandom in parallel. The programs are almost |
| 769 | * certainly doing something terribly wrong, but we'll work around |
| 770 | * their brain damage. |
| 771 | */ |
| 772 | static struct crng_state **crng_node_pool __read_mostly; |
| 773 | #endif |
| 774 | |
| 775 | static void invalidate_batched_entropy(void); |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 776 | static void numa_crng_init(void); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 777 | |
| 778 | static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU); |
| 779 | static int __init parse_trust_cpu(char *arg) |
| 780 | { |
| 781 | return kstrtobool(arg, &trust_cpu); |
| 782 | } |
| 783 | early_param("random.trust_cpu", parse_trust_cpu); |
| 784 | |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 785 | static bool crng_init_try_arch(struct crng_state *crng) |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 786 | { |
| 787 | int i; |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 788 | bool arch_init = true; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 789 | unsigned long rv; |
| 790 | |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 791 | for (i = 4; i < 16; i++) { |
| 792 | if (!arch_get_random_seed_long(&rv) && |
| 793 | !arch_get_random_long(&rv)) { |
| 794 | rv = random_get_entropy(); |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 795 | arch_init = false; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 796 | } |
| 797 | crng->state[i] ^= rv; |
| 798 | } |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 799 | |
| 800 | return arch_init; |
| 801 | } |
| 802 | |
| 803 | static bool __init crng_init_try_arch_early(struct crng_state *crng) |
| 804 | { |
| 805 | int i; |
| 806 | bool arch_init = true; |
| 807 | unsigned long rv; |
| 808 | |
| 809 | for (i = 4; i < 16; i++) { |
| 810 | if (!arch_get_random_seed_long_early(&rv) && |
| 811 | !arch_get_random_long_early(&rv)) { |
| 812 | rv = random_get_entropy(); |
| 813 | arch_init = false; |
| 814 | } |
| 815 | crng->state[i] ^= rv; |
| 816 | } |
| 817 | |
| 818 | return arch_init; |
| 819 | } |
| 820 | |
| 821 | static void __maybe_unused crng_initialize_secondary(struct crng_state *crng) |
| 822 | { |
| 823 | chacha_init_consts(crng->state); |
| 824 | _get_random_bytes(&crng->state[4], sizeof(__u32) * 12); |
| 825 | crng_init_try_arch(crng); |
| 826 | crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1; |
| 827 | } |
| 828 | |
| 829 | static void __init crng_initialize_primary(struct crng_state *crng) |
| 830 | { |
| 831 | chacha_init_consts(crng->state); |
| 832 | _extract_entropy(&input_pool, &crng->state[4], sizeof(__u32) * 12, 0); |
| 833 | if (crng_init_try_arch_early(crng) && trust_cpu) { |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 834 | invalidate_batched_entropy(); |
| 835 | numa_crng_init(); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 836 | crng_init = 2; |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 837 | pr_notice("crng done (trusting CPU's manufacturer)\n"); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 838 | } |
| 839 | crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1; |
| 840 | } |
| 841 | |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 842 | static void crng_finalize_init(struct crng_state *crng) |
| 843 | { |
| 844 | if (crng != &primary_crng || crng_init >= 2) |
| 845 | return; |
| 846 | if (!system_wq) { |
| 847 | /* We can't call numa_crng_init until we have workqueues, |
| 848 | * so mark this for processing later. */ |
| 849 | crng_need_final_init = true; |
| 850 | return; |
| 851 | } |
| 852 | |
| 853 | invalidate_batched_entropy(); |
| 854 | numa_crng_init(); |
| 855 | crng_init = 2; |
| 856 | process_random_ready_list(); |
| 857 | wake_up_interruptible(&crng_init_wait); |
| 858 | kill_fasync(&fasync, SIGIO, POLL_IN); |
| 859 | pr_notice("crng init done\n"); |
| 860 | if (unseeded_warning.missed) { |
| 861 | pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n", |
| 862 | unseeded_warning.missed); |
| 863 | unseeded_warning.missed = 0; |
| 864 | } |
| 865 | if (urandom_warning.missed) { |
| 866 | pr_notice("%d urandom warning(s) missed due to ratelimiting\n", |
| 867 | urandom_warning.missed); |
| 868 | urandom_warning.missed = 0; |
| 869 | } |
| 870 | } |
| 871 | |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 872 | #ifdef CONFIG_NUMA |
| 873 | static void do_numa_crng_init(struct work_struct *work) |
| 874 | { |
| 875 | int i; |
| 876 | struct crng_state *crng; |
| 877 | struct crng_state **pool; |
| 878 | |
| 879 | pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL|__GFP_NOFAIL); |
| 880 | for_each_online_node(i) { |
| 881 | crng = kmalloc_node(sizeof(struct crng_state), |
| 882 | GFP_KERNEL | __GFP_NOFAIL, i); |
| 883 | spin_lock_init(&crng->lock); |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 884 | crng_initialize_secondary(crng); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 885 | pool[i] = crng; |
| 886 | } |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 887 | /* pairs with READ_ONCE() in select_crng() */ |
| 888 | if (cmpxchg_release(&crng_node_pool, NULL, pool) != NULL) { |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 889 | for_each_node(i) |
| 890 | kfree(pool[i]); |
| 891 | kfree(pool); |
| 892 | } |
| 893 | } |
| 894 | |
| 895 | static DECLARE_WORK(numa_crng_init_work, do_numa_crng_init); |
| 896 | |
| 897 | static void numa_crng_init(void) |
| 898 | { |
| 899 | schedule_work(&numa_crng_init_work); |
| 900 | } |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 901 | |
| 902 | static struct crng_state *select_crng(void) |
| 903 | { |
| 904 | struct crng_state **pool; |
| 905 | int nid = numa_node_id(); |
| 906 | |
| 907 | /* pairs with cmpxchg_release() in do_numa_crng_init() */ |
| 908 | pool = READ_ONCE(crng_node_pool); |
| 909 | if (pool && pool[nid]) |
| 910 | return pool[nid]; |
| 911 | |
| 912 | return &primary_crng; |
| 913 | } |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 914 | #else |
| 915 | static void numa_crng_init(void) {} |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 916 | |
| 917 | static struct crng_state *select_crng(void) |
| 918 | { |
| 919 | return &primary_crng; |
| 920 | } |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 921 | #endif |
| 922 | |
| 923 | /* |
| 924 | * crng_fast_load() can be called by code in the interrupt service |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 925 | * path. So we can't afford to dilly-dally. Returns the number of |
| 926 | * bytes processed from cp. |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 927 | */ |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 928 | static size_t crng_fast_load(const char *cp, size_t len) |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 929 | { |
| 930 | unsigned long flags; |
| 931 | char *p; |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 932 | size_t ret = 0; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 933 | |
| 934 | if (!spin_trylock_irqsave(&primary_crng.lock, flags)) |
| 935 | return 0; |
| 936 | if (crng_init != 0) { |
| 937 | spin_unlock_irqrestore(&primary_crng.lock, flags); |
| 938 | return 0; |
| 939 | } |
| 940 | p = (unsigned char *) &primary_crng.state[4]; |
| 941 | while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) { |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 942 | p[crng_init_cnt % CHACHA_KEY_SIZE] ^= *cp; |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 943 | cp++; crng_init_cnt++; len--; ret++; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 944 | } |
| 945 | spin_unlock_irqrestore(&primary_crng.lock, flags); |
| 946 | if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) { |
| 947 | invalidate_batched_entropy(); |
| 948 | crng_init = 1; |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 949 | pr_notice("fast init done\n"); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 950 | } |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 951 | return ret; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 952 | } |
| 953 | |
| 954 | /* |
| 955 | * crng_slow_load() is called by add_device_randomness, which has two |
| 956 | * attributes. (1) We can't trust the buffer passed to it is |
| 957 | * guaranteed to be unpredictable (so it might not have any entropy at |
| 958 | * all), and (2) it doesn't have the performance constraints of |
| 959 | * crng_fast_load(). |
| 960 | * |
| 961 | * So we do something more comprehensive which is guaranteed to touch |
| 962 | * all of the primary_crng's state, and which uses a LFSR with a |
| 963 | * period of 255 as part of the mixing algorithm. Finally, we do |
| 964 | * *not* advance crng_init_cnt since buffer we may get may be something |
| 965 | * like a fixed DMI table (for example), which might very well be |
| 966 | * unique to the machine, but is otherwise unvarying. |
| 967 | */ |
| 968 | static int crng_slow_load(const char *cp, size_t len) |
| 969 | { |
| 970 | unsigned long flags; |
| 971 | static unsigned char lfsr = 1; |
| 972 | unsigned char tmp; |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 973 | unsigned i, max = CHACHA_KEY_SIZE; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 974 | const char * src_buf = cp; |
| 975 | char * dest_buf = (char *) &primary_crng.state[4]; |
| 976 | |
| 977 | if (!spin_trylock_irqsave(&primary_crng.lock, flags)) |
| 978 | return 0; |
| 979 | if (crng_init != 0) { |
| 980 | spin_unlock_irqrestore(&primary_crng.lock, flags); |
| 981 | return 0; |
| 982 | } |
| 983 | if (len > max) |
| 984 | max = len; |
| 985 | |
| 986 | for (i = 0; i < max ; i++) { |
| 987 | tmp = lfsr; |
| 988 | lfsr >>= 1; |
| 989 | if (tmp & 1) |
| 990 | lfsr ^= 0xE1; |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 991 | tmp = dest_buf[i % CHACHA_KEY_SIZE]; |
| 992 | dest_buf[i % CHACHA_KEY_SIZE] ^= src_buf[i % len] ^ lfsr; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 993 | lfsr += (tmp << 3) | (tmp >> 5); |
| 994 | } |
| 995 | spin_unlock_irqrestore(&primary_crng.lock, flags); |
| 996 | return 1; |
| 997 | } |
| 998 | |
| 999 | static void crng_reseed(struct crng_state *crng, struct entropy_store *r) |
| 1000 | { |
| 1001 | unsigned long flags; |
| 1002 | int i, num; |
| 1003 | union { |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1004 | __u8 block[CHACHA_BLOCK_SIZE]; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1005 | __u32 key[8]; |
| 1006 | } buf; |
| 1007 | |
| 1008 | if (r) { |
| 1009 | num = extract_entropy(r, &buf, 32, 16, 0); |
| 1010 | if (num == 0) |
| 1011 | return; |
| 1012 | } else { |
| 1013 | _extract_crng(&primary_crng, buf.block); |
| 1014 | _crng_backtrack_protect(&primary_crng, buf.block, |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1015 | CHACHA_KEY_SIZE); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1016 | } |
| 1017 | spin_lock_irqsave(&crng->lock, flags); |
| 1018 | for (i = 0; i < 8; i++) { |
| 1019 | unsigned long rv; |
| 1020 | if (!arch_get_random_seed_long(&rv) && |
| 1021 | !arch_get_random_long(&rv)) |
| 1022 | rv = random_get_entropy(); |
| 1023 | crng->state[i+4] ^= buf.key[i] ^ rv; |
| 1024 | } |
| 1025 | memzero_explicit(&buf, sizeof(buf)); |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1026 | WRITE_ONCE(crng->init_time, jiffies); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1027 | spin_unlock_irqrestore(&crng->lock, flags); |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1028 | crng_finalize_init(crng); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1029 | } |
| 1030 | |
| 1031 | static void _extract_crng(struct crng_state *crng, |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1032 | __u8 out[CHACHA_BLOCK_SIZE]) |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1033 | { |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1034 | unsigned long v, flags, init_time; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1035 | |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1036 | if (crng_ready()) { |
| 1037 | init_time = READ_ONCE(crng->init_time); |
| 1038 | if (time_after(READ_ONCE(crng_global_init_time), init_time) || |
| 1039 | time_after(jiffies, init_time + CRNG_RESEED_INTERVAL)) |
| 1040 | crng_reseed(crng, crng == &primary_crng ? |
| 1041 | &input_pool : NULL); |
| 1042 | } |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1043 | spin_lock_irqsave(&crng->lock, flags); |
| 1044 | if (arch_get_random_long(&v)) |
| 1045 | crng->state[14] ^= v; |
| 1046 | chacha20_block(&crng->state[0], out); |
| 1047 | if (crng->state[12] == 0) |
| 1048 | crng->state[13]++; |
| 1049 | spin_unlock_irqrestore(&crng->lock, flags); |
| 1050 | } |
| 1051 | |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1052 | static void extract_crng(__u8 out[CHACHA_BLOCK_SIZE]) |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1053 | { |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1054 | _extract_crng(select_crng(), out); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1055 | } |
| 1056 | |
| 1057 | /* |
| 1058 | * Use the leftover bytes from the CRNG block output (if there is |
| 1059 | * enough) to mutate the CRNG key to provide backtracking protection. |
| 1060 | */ |
| 1061 | static void _crng_backtrack_protect(struct crng_state *crng, |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1062 | __u8 tmp[CHACHA_BLOCK_SIZE], int used) |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1063 | { |
| 1064 | unsigned long flags; |
| 1065 | __u32 *s, *d; |
| 1066 | int i; |
| 1067 | |
| 1068 | used = round_up(used, sizeof(__u32)); |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1069 | if (used + CHACHA_KEY_SIZE > CHACHA_BLOCK_SIZE) { |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1070 | extract_crng(tmp); |
| 1071 | used = 0; |
| 1072 | } |
| 1073 | spin_lock_irqsave(&crng->lock, flags); |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1074 | s = (__u32 *) &tmp[used]; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1075 | d = &crng->state[4]; |
| 1076 | for (i=0; i < 8; i++) |
| 1077 | *d++ ^= *s++; |
| 1078 | spin_unlock_irqrestore(&crng->lock, flags); |
| 1079 | } |
| 1080 | |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1081 | static void crng_backtrack_protect(__u8 tmp[CHACHA_BLOCK_SIZE], int used) |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1082 | { |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1083 | _crng_backtrack_protect(select_crng(), tmp, used); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1084 | } |
| 1085 | |
| 1086 | static ssize_t extract_crng_user(void __user *buf, size_t nbytes) |
| 1087 | { |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1088 | ssize_t ret = 0, i = CHACHA_BLOCK_SIZE; |
| 1089 | __u8 tmp[CHACHA_BLOCK_SIZE] __aligned(4); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1090 | int large_request = (nbytes > 256); |
| 1091 | |
| 1092 | while (nbytes) { |
| 1093 | if (large_request && need_resched()) { |
| 1094 | if (signal_pending(current)) { |
| 1095 | if (ret == 0) |
| 1096 | ret = -ERESTARTSYS; |
| 1097 | break; |
| 1098 | } |
| 1099 | schedule(); |
| 1100 | } |
| 1101 | |
| 1102 | extract_crng(tmp); |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1103 | i = min_t(int, nbytes, CHACHA_BLOCK_SIZE); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1104 | if (copy_to_user(buf, tmp, i)) { |
| 1105 | ret = -EFAULT; |
| 1106 | break; |
| 1107 | } |
| 1108 | |
| 1109 | nbytes -= i; |
| 1110 | buf += i; |
| 1111 | ret += i; |
| 1112 | } |
| 1113 | crng_backtrack_protect(tmp, i); |
| 1114 | |
| 1115 | /* Wipe data just written to memory */ |
| 1116 | memzero_explicit(tmp, sizeof(tmp)); |
| 1117 | |
| 1118 | return ret; |
| 1119 | } |
| 1120 | |
| 1121 | |
| 1122 | /********************************************************************* |
| 1123 | * |
| 1124 | * Entropy input management |
| 1125 | * |
| 1126 | *********************************************************************/ |
| 1127 | |
| 1128 | /* There is one of these per entropy source */ |
| 1129 | struct timer_rand_state { |
| 1130 | cycles_t last_time; |
| 1131 | long last_delta, last_delta2; |
| 1132 | }; |
| 1133 | |
| 1134 | #define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, }; |
| 1135 | |
| 1136 | /* |
| 1137 | * Add device- or boot-specific data to the input pool to help |
| 1138 | * initialize it. |
| 1139 | * |
| 1140 | * None of this adds any entropy; it is meant to avoid the problem of |
| 1141 | * the entropy pool having similar initial state across largely |
| 1142 | * identical devices. |
| 1143 | */ |
| 1144 | void add_device_randomness(const void *buf, unsigned int size) |
| 1145 | { |
| 1146 | unsigned long time = random_get_entropy() ^ jiffies; |
| 1147 | unsigned long flags; |
| 1148 | |
| 1149 | if (!crng_ready() && size) |
| 1150 | crng_slow_load(buf, size); |
| 1151 | |
| 1152 | trace_add_device_randomness(size, _RET_IP_); |
| 1153 | spin_lock_irqsave(&input_pool.lock, flags); |
| 1154 | _mix_pool_bytes(&input_pool, buf, size); |
| 1155 | _mix_pool_bytes(&input_pool, &time, sizeof(time)); |
| 1156 | spin_unlock_irqrestore(&input_pool.lock, flags); |
| 1157 | } |
| 1158 | EXPORT_SYMBOL(add_device_randomness); |
| 1159 | |
| 1160 | static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE; |
| 1161 | |
| 1162 | /* |
| 1163 | * This function adds entropy to the entropy "pool" by using timing |
| 1164 | * delays. It uses the timer_rand_state structure to make an estimate |
| 1165 | * of how many bits of entropy this call has added to the pool. |
| 1166 | * |
| 1167 | * The number "num" is also added to the pool - it should somehow describe |
| 1168 | * the type of event which just happened. This is currently 0-255 for |
| 1169 | * keyboard scan codes, and 256 upwards for interrupts. |
| 1170 | * |
| 1171 | */ |
| 1172 | static void add_timer_randomness(struct timer_rand_state *state, unsigned num) |
| 1173 | { |
| 1174 | struct entropy_store *r; |
| 1175 | struct { |
| 1176 | long jiffies; |
| 1177 | unsigned cycles; |
| 1178 | unsigned num; |
| 1179 | } sample; |
| 1180 | long delta, delta2, delta3; |
| 1181 | |
| 1182 | sample.jiffies = jiffies; |
| 1183 | sample.cycles = random_get_entropy(); |
| 1184 | sample.num = num; |
| 1185 | r = &input_pool; |
| 1186 | mix_pool_bytes(r, &sample, sizeof(sample)); |
| 1187 | |
| 1188 | /* |
| 1189 | * Calculate number of bits of randomness we probably added. |
| 1190 | * We take into account the first, second and third-order deltas |
| 1191 | * in order to make our estimate. |
| 1192 | */ |
Olivier Deprez | 0e64123 | 2021-09-23 10:07:05 +0200 | [diff] [blame] | 1193 | delta = sample.jiffies - READ_ONCE(state->last_time); |
| 1194 | WRITE_ONCE(state->last_time, sample.jiffies); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1195 | |
Olivier Deprez | 0e64123 | 2021-09-23 10:07:05 +0200 | [diff] [blame] | 1196 | delta2 = delta - READ_ONCE(state->last_delta); |
| 1197 | WRITE_ONCE(state->last_delta, delta); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1198 | |
Olivier Deprez | 0e64123 | 2021-09-23 10:07:05 +0200 | [diff] [blame] | 1199 | delta3 = delta2 - READ_ONCE(state->last_delta2); |
| 1200 | WRITE_ONCE(state->last_delta2, delta2); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1201 | |
| 1202 | if (delta < 0) |
| 1203 | delta = -delta; |
| 1204 | if (delta2 < 0) |
| 1205 | delta2 = -delta2; |
| 1206 | if (delta3 < 0) |
| 1207 | delta3 = -delta3; |
| 1208 | if (delta > delta2) |
| 1209 | delta = delta2; |
| 1210 | if (delta > delta3) |
| 1211 | delta = delta3; |
| 1212 | |
| 1213 | /* |
| 1214 | * delta is now minimum absolute delta. |
| 1215 | * Round down by 1 bit on general principles, |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1216 | * and limit entropy estimate to 12 bits. |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1217 | */ |
| 1218 | credit_entropy_bits(r, min_t(int, fls(delta>>1), 11)); |
| 1219 | } |
| 1220 | |
| 1221 | void add_input_randomness(unsigned int type, unsigned int code, |
| 1222 | unsigned int value) |
| 1223 | { |
| 1224 | static unsigned char last_value; |
| 1225 | |
| 1226 | /* ignore autorepeat and the like */ |
| 1227 | if (value == last_value) |
| 1228 | return; |
| 1229 | |
| 1230 | last_value = value; |
| 1231 | add_timer_randomness(&input_timer_state, |
| 1232 | (type << 4) ^ code ^ (code >> 4) ^ value); |
| 1233 | trace_add_input_randomness(ENTROPY_BITS(&input_pool)); |
| 1234 | } |
| 1235 | EXPORT_SYMBOL_GPL(add_input_randomness); |
| 1236 | |
| 1237 | static DEFINE_PER_CPU(struct fast_pool, irq_randomness); |
| 1238 | |
| 1239 | #ifdef ADD_INTERRUPT_BENCH |
| 1240 | static unsigned long avg_cycles, avg_deviation; |
| 1241 | |
| 1242 | #define AVG_SHIFT 8 /* Exponential average factor k=1/256 */ |
| 1243 | #define FIXED_1_2 (1 << (AVG_SHIFT-1)) |
| 1244 | |
| 1245 | static void add_interrupt_bench(cycles_t start) |
| 1246 | { |
| 1247 | long delta = random_get_entropy() - start; |
| 1248 | |
| 1249 | /* Use a weighted moving average */ |
| 1250 | delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT); |
| 1251 | avg_cycles += delta; |
| 1252 | /* And average deviation */ |
| 1253 | delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT); |
| 1254 | avg_deviation += delta; |
| 1255 | } |
| 1256 | #else |
| 1257 | #define add_interrupt_bench(x) |
| 1258 | #endif |
| 1259 | |
| 1260 | static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs) |
| 1261 | { |
| 1262 | __u32 *ptr = (__u32 *) regs; |
| 1263 | unsigned int idx; |
| 1264 | |
| 1265 | if (regs == NULL) |
| 1266 | return 0; |
| 1267 | idx = READ_ONCE(f->reg_idx); |
| 1268 | if (idx >= sizeof(struct pt_regs) / sizeof(__u32)) |
| 1269 | idx = 0; |
| 1270 | ptr += idx++; |
| 1271 | WRITE_ONCE(f->reg_idx, idx); |
| 1272 | return *ptr; |
| 1273 | } |
| 1274 | |
| 1275 | void add_interrupt_randomness(int irq, int irq_flags) |
| 1276 | { |
| 1277 | struct entropy_store *r; |
| 1278 | struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness); |
| 1279 | struct pt_regs *regs = get_irq_regs(); |
| 1280 | unsigned long now = jiffies; |
| 1281 | cycles_t cycles = random_get_entropy(); |
| 1282 | __u32 c_high, j_high; |
| 1283 | __u64 ip; |
| 1284 | unsigned long seed; |
| 1285 | int credit = 0; |
| 1286 | |
| 1287 | if (cycles == 0) |
| 1288 | cycles = get_reg(fast_pool, regs); |
| 1289 | c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0; |
| 1290 | j_high = (sizeof(now) > 4) ? now >> 32 : 0; |
| 1291 | fast_pool->pool[0] ^= cycles ^ j_high ^ irq; |
| 1292 | fast_pool->pool[1] ^= now ^ c_high; |
| 1293 | ip = regs ? instruction_pointer(regs) : _RET_IP_; |
| 1294 | fast_pool->pool[2] ^= ip; |
| 1295 | fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 : |
| 1296 | get_reg(fast_pool, regs); |
| 1297 | |
| 1298 | fast_mix(fast_pool); |
| 1299 | add_interrupt_bench(cycles); |
| 1300 | |
| 1301 | if (unlikely(crng_init == 0)) { |
| 1302 | if ((fast_pool->count >= 64) && |
| 1303 | crng_fast_load((char *) fast_pool->pool, |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1304 | sizeof(fast_pool->pool)) > 0) { |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1305 | fast_pool->count = 0; |
| 1306 | fast_pool->last = now; |
| 1307 | } |
| 1308 | return; |
| 1309 | } |
| 1310 | |
| 1311 | if ((fast_pool->count < 64) && |
| 1312 | !time_after(now, fast_pool->last + HZ)) |
| 1313 | return; |
| 1314 | |
| 1315 | r = &input_pool; |
| 1316 | if (!spin_trylock(&r->lock)) |
| 1317 | return; |
| 1318 | |
| 1319 | fast_pool->last = now; |
| 1320 | __mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool)); |
| 1321 | |
| 1322 | /* |
| 1323 | * If we have architectural seed generator, produce a seed and |
| 1324 | * add it to the pool. For the sake of paranoia don't let the |
| 1325 | * architectural seed generator dominate the input from the |
| 1326 | * interrupt noise. |
| 1327 | */ |
| 1328 | if (arch_get_random_seed_long(&seed)) { |
| 1329 | __mix_pool_bytes(r, &seed, sizeof(seed)); |
| 1330 | credit = 1; |
| 1331 | } |
| 1332 | spin_unlock(&r->lock); |
| 1333 | |
| 1334 | fast_pool->count = 0; |
| 1335 | |
| 1336 | /* award one bit for the contents of the fast pool */ |
| 1337 | credit_entropy_bits(r, credit + 1); |
| 1338 | } |
| 1339 | EXPORT_SYMBOL_GPL(add_interrupt_randomness); |
| 1340 | |
| 1341 | #ifdef CONFIG_BLOCK |
| 1342 | void add_disk_randomness(struct gendisk *disk) |
| 1343 | { |
| 1344 | if (!disk || !disk->random) |
| 1345 | return; |
| 1346 | /* first major is 1, so we get >= 0x200 here */ |
| 1347 | add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); |
| 1348 | trace_add_disk_randomness(disk_devt(disk), ENTROPY_BITS(&input_pool)); |
| 1349 | } |
| 1350 | EXPORT_SYMBOL_GPL(add_disk_randomness); |
| 1351 | #endif |
| 1352 | |
| 1353 | /********************************************************************* |
| 1354 | * |
| 1355 | * Entropy extraction routines |
| 1356 | * |
| 1357 | *********************************************************************/ |
| 1358 | |
| 1359 | /* |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1360 | * This function decides how many bytes to actually take from the |
| 1361 | * given pool, and also debits the entropy count accordingly. |
| 1362 | */ |
| 1363 | static size_t account(struct entropy_store *r, size_t nbytes, int min, |
| 1364 | int reserved) |
| 1365 | { |
| 1366 | int entropy_count, orig, have_bytes; |
| 1367 | size_t ibytes, nfrac; |
| 1368 | |
| 1369 | BUG_ON(r->entropy_count > r->poolinfo->poolfracbits); |
| 1370 | |
| 1371 | /* Can we pull enough? */ |
| 1372 | retry: |
| 1373 | entropy_count = orig = READ_ONCE(r->entropy_count); |
| 1374 | ibytes = nbytes; |
| 1375 | /* never pull more than available */ |
| 1376 | have_bytes = entropy_count >> (ENTROPY_SHIFT + 3); |
| 1377 | |
| 1378 | if ((have_bytes -= reserved) < 0) |
| 1379 | have_bytes = 0; |
| 1380 | ibytes = min_t(size_t, ibytes, have_bytes); |
| 1381 | if (ibytes < min) |
| 1382 | ibytes = 0; |
| 1383 | |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1384 | if (WARN_ON(entropy_count < 0)) { |
| 1385 | pr_warn("negative entropy count: pool %s count %d\n", |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1386 | r->name, entropy_count); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1387 | entropy_count = 0; |
| 1388 | } |
| 1389 | nfrac = ibytes << (ENTROPY_SHIFT + 3); |
| 1390 | if ((size_t) entropy_count > nfrac) |
| 1391 | entropy_count -= nfrac; |
| 1392 | else |
| 1393 | entropy_count = 0; |
| 1394 | |
| 1395 | if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) |
| 1396 | goto retry; |
| 1397 | |
| 1398 | trace_debit_entropy(r->name, 8 * ibytes); |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1399 | if (ibytes && ENTROPY_BITS(r) < random_write_wakeup_bits) { |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1400 | wake_up_interruptible(&random_write_wait); |
| 1401 | kill_fasync(&fasync, SIGIO, POLL_OUT); |
| 1402 | } |
| 1403 | |
| 1404 | return ibytes; |
| 1405 | } |
| 1406 | |
| 1407 | /* |
| 1408 | * This function does the actual extraction for extract_entropy and |
| 1409 | * extract_entropy_user. |
| 1410 | * |
| 1411 | * Note: we assume that .poolwords is a multiple of 16 words. |
| 1412 | */ |
| 1413 | static void extract_buf(struct entropy_store *r, __u8 *out) |
| 1414 | { |
| 1415 | int i; |
| 1416 | union { |
| 1417 | __u32 w[5]; |
| 1418 | unsigned long l[LONGS(20)]; |
| 1419 | } hash; |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1420 | __u32 workspace[SHA1_WORKSPACE_WORDS]; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1421 | unsigned long flags; |
| 1422 | |
| 1423 | /* |
| 1424 | * If we have an architectural hardware random number |
| 1425 | * generator, use it for SHA's initial vector |
| 1426 | */ |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1427 | sha1_init(hash.w); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1428 | for (i = 0; i < LONGS(20); i++) { |
| 1429 | unsigned long v; |
| 1430 | if (!arch_get_random_long(&v)) |
| 1431 | break; |
| 1432 | hash.l[i] = v; |
| 1433 | } |
| 1434 | |
| 1435 | /* Generate a hash across the pool, 16 words (512 bits) at a time */ |
| 1436 | spin_lock_irqsave(&r->lock, flags); |
| 1437 | for (i = 0; i < r->poolinfo->poolwords; i += 16) |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1438 | sha1_transform(hash.w, (__u8 *)(r->pool + i), workspace); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1439 | |
| 1440 | /* |
| 1441 | * We mix the hash back into the pool to prevent backtracking |
| 1442 | * attacks (where the attacker knows the state of the pool |
| 1443 | * plus the current outputs, and attempts to find previous |
| 1444 | * ouputs), unless the hash function can be inverted. By |
| 1445 | * mixing at least a SHA1 worth of hash data back, we make |
| 1446 | * brute-forcing the feedback as hard as brute-forcing the |
| 1447 | * hash. |
| 1448 | */ |
| 1449 | __mix_pool_bytes(r, hash.w, sizeof(hash.w)); |
| 1450 | spin_unlock_irqrestore(&r->lock, flags); |
| 1451 | |
| 1452 | memzero_explicit(workspace, sizeof(workspace)); |
| 1453 | |
| 1454 | /* |
| 1455 | * In case the hash function has some recognizable output |
| 1456 | * pattern, we fold it in half. Thus, we always feed back |
| 1457 | * twice as much data as we output. |
| 1458 | */ |
| 1459 | hash.w[0] ^= hash.w[3]; |
| 1460 | hash.w[1] ^= hash.w[4]; |
| 1461 | hash.w[2] ^= rol32(hash.w[2], 16); |
| 1462 | |
| 1463 | memcpy(out, &hash, EXTRACT_SIZE); |
| 1464 | memzero_explicit(&hash, sizeof(hash)); |
| 1465 | } |
| 1466 | |
| 1467 | static ssize_t _extract_entropy(struct entropy_store *r, void *buf, |
| 1468 | size_t nbytes, int fips) |
| 1469 | { |
| 1470 | ssize_t ret = 0, i; |
| 1471 | __u8 tmp[EXTRACT_SIZE]; |
| 1472 | unsigned long flags; |
| 1473 | |
| 1474 | while (nbytes) { |
| 1475 | extract_buf(r, tmp); |
| 1476 | |
| 1477 | if (fips) { |
| 1478 | spin_lock_irqsave(&r->lock, flags); |
| 1479 | if (!memcmp(tmp, r->last_data, EXTRACT_SIZE)) |
| 1480 | panic("Hardware RNG duplicated output!\n"); |
| 1481 | memcpy(r->last_data, tmp, EXTRACT_SIZE); |
| 1482 | spin_unlock_irqrestore(&r->lock, flags); |
| 1483 | } |
| 1484 | i = min_t(int, nbytes, EXTRACT_SIZE); |
| 1485 | memcpy(buf, tmp, i); |
| 1486 | nbytes -= i; |
| 1487 | buf += i; |
| 1488 | ret += i; |
| 1489 | } |
| 1490 | |
| 1491 | /* Wipe data just returned from memory */ |
| 1492 | memzero_explicit(tmp, sizeof(tmp)); |
| 1493 | |
| 1494 | return ret; |
| 1495 | } |
| 1496 | |
| 1497 | /* |
| 1498 | * This function extracts randomness from the "entropy pool", and |
| 1499 | * returns it in a buffer. |
| 1500 | * |
| 1501 | * The min parameter specifies the minimum amount we can pull before |
| 1502 | * failing to avoid races that defeat catastrophic reseeding while the |
| 1503 | * reserved parameter indicates how much entropy we must leave in the |
| 1504 | * pool after each pull to avoid starving other readers. |
| 1505 | */ |
| 1506 | static ssize_t extract_entropy(struct entropy_store *r, void *buf, |
| 1507 | size_t nbytes, int min, int reserved) |
| 1508 | { |
| 1509 | __u8 tmp[EXTRACT_SIZE]; |
| 1510 | unsigned long flags; |
| 1511 | |
| 1512 | /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */ |
| 1513 | if (fips_enabled) { |
| 1514 | spin_lock_irqsave(&r->lock, flags); |
| 1515 | if (!r->last_data_init) { |
| 1516 | r->last_data_init = 1; |
| 1517 | spin_unlock_irqrestore(&r->lock, flags); |
| 1518 | trace_extract_entropy(r->name, EXTRACT_SIZE, |
| 1519 | ENTROPY_BITS(r), _RET_IP_); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1520 | extract_buf(r, tmp); |
| 1521 | spin_lock_irqsave(&r->lock, flags); |
| 1522 | memcpy(r->last_data, tmp, EXTRACT_SIZE); |
| 1523 | } |
| 1524 | spin_unlock_irqrestore(&r->lock, flags); |
| 1525 | } |
| 1526 | |
| 1527 | trace_extract_entropy(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1528 | nbytes = account(r, nbytes, min, reserved); |
| 1529 | |
| 1530 | return _extract_entropy(r, buf, nbytes, fips_enabled); |
| 1531 | } |
| 1532 | |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1533 | #define warn_unseeded_randomness(previous) \ |
| 1534 | _warn_unseeded_randomness(__func__, (void *) _RET_IP_, (previous)) |
| 1535 | |
| 1536 | static void _warn_unseeded_randomness(const char *func_name, void *caller, |
| 1537 | void **previous) |
| 1538 | { |
| 1539 | #ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM |
| 1540 | const bool print_once = false; |
| 1541 | #else |
| 1542 | static bool print_once __read_mostly; |
| 1543 | #endif |
| 1544 | |
| 1545 | if (print_once || |
| 1546 | crng_ready() || |
| 1547 | (previous && (caller == READ_ONCE(*previous)))) |
| 1548 | return; |
| 1549 | WRITE_ONCE(*previous, caller); |
| 1550 | #ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM |
| 1551 | print_once = true; |
| 1552 | #endif |
| 1553 | if (__ratelimit(&unseeded_warning)) |
Olivier Deprez | 0e64123 | 2021-09-23 10:07:05 +0200 | [diff] [blame] | 1554 | printk_deferred(KERN_NOTICE "random: %s called from %pS " |
| 1555 | "with crng_init=%d\n", func_name, caller, |
| 1556 | crng_init); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1557 | } |
| 1558 | |
| 1559 | /* |
| 1560 | * This function is the exported kernel interface. It returns some |
| 1561 | * number of good random numbers, suitable for key generation, seeding |
| 1562 | * TCP sequence numbers, etc. It does not rely on the hardware random |
| 1563 | * number generator. For random bytes direct from the hardware RNG |
| 1564 | * (when available), use get_random_bytes_arch(). In order to ensure |
| 1565 | * that the randomness provided by this function is okay, the function |
| 1566 | * wait_for_random_bytes() should be called and return 0 at least once |
| 1567 | * at any point prior. |
| 1568 | */ |
| 1569 | static void _get_random_bytes(void *buf, int nbytes) |
| 1570 | { |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1571 | __u8 tmp[CHACHA_BLOCK_SIZE] __aligned(4); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1572 | |
| 1573 | trace_get_random_bytes(nbytes, _RET_IP_); |
| 1574 | |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1575 | while (nbytes >= CHACHA_BLOCK_SIZE) { |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1576 | extract_crng(buf); |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1577 | buf += CHACHA_BLOCK_SIZE; |
| 1578 | nbytes -= CHACHA_BLOCK_SIZE; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1579 | } |
| 1580 | |
| 1581 | if (nbytes > 0) { |
| 1582 | extract_crng(tmp); |
| 1583 | memcpy(buf, tmp, nbytes); |
| 1584 | crng_backtrack_protect(tmp, nbytes); |
| 1585 | } else |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1586 | crng_backtrack_protect(tmp, CHACHA_BLOCK_SIZE); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1587 | memzero_explicit(tmp, sizeof(tmp)); |
| 1588 | } |
| 1589 | |
| 1590 | void get_random_bytes(void *buf, int nbytes) |
| 1591 | { |
| 1592 | static void *previous; |
| 1593 | |
| 1594 | warn_unseeded_randomness(&previous); |
| 1595 | _get_random_bytes(buf, nbytes); |
| 1596 | } |
| 1597 | EXPORT_SYMBOL(get_random_bytes); |
| 1598 | |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1599 | |
| 1600 | /* |
| 1601 | * Each time the timer fires, we expect that we got an unpredictable |
| 1602 | * jump in the cycle counter. Even if the timer is running on another |
| 1603 | * CPU, the timer activity will be touching the stack of the CPU that is |
| 1604 | * generating entropy.. |
| 1605 | * |
| 1606 | * Note that we don't re-arm the timer in the timer itself - we are |
| 1607 | * happy to be scheduled away, since that just makes the load more |
| 1608 | * complex, but we do not want the timer to keep ticking unless the |
| 1609 | * entropy loop is running. |
| 1610 | * |
| 1611 | * So the re-arming always happens in the entropy loop itself. |
| 1612 | */ |
| 1613 | static void entropy_timer(struct timer_list *t) |
| 1614 | { |
| 1615 | credit_entropy_bits(&input_pool, 1); |
| 1616 | } |
| 1617 | |
| 1618 | /* |
| 1619 | * If we have an actual cycle counter, see if we can |
| 1620 | * generate enough entropy with timing noise |
| 1621 | */ |
| 1622 | static void try_to_generate_entropy(void) |
| 1623 | { |
| 1624 | struct { |
| 1625 | unsigned long now; |
| 1626 | struct timer_list timer; |
| 1627 | } stack; |
| 1628 | |
| 1629 | stack.now = random_get_entropy(); |
| 1630 | |
| 1631 | /* Slow counter - or none. Don't even bother */ |
| 1632 | if (stack.now == random_get_entropy()) |
| 1633 | return; |
| 1634 | |
| 1635 | timer_setup_on_stack(&stack.timer, entropy_timer, 0); |
| 1636 | while (!crng_ready()) { |
| 1637 | if (!timer_pending(&stack.timer)) |
| 1638 | mod_timer(&stack.timer, jiffies+1); |
| 1639 | mix_pool_bytes(&input_pool, &stack.now, sizeof(stack.now)); |
| 1640 | schedule(); |
| 1641 | stack.now = random_get_entropy(); |
| 1642 | } |
| 1643 | |
| 1644 | del_timer_sync(&stack.timer); |
| 1645 | destroy_timer_on_stack(&stack.timer); |
| 1646 | mix_pool_bytes(&input_pool, &stack.now, sizeof(stack.now)); |
| 1647 | } |
| 1648 | |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1649 | /* |
| 1650 | * Wait for the urandom pool to be seeded and thus guaranteed to supply |
| 1651 | * cryptographically secure random numbers. This applies to: the /dev/urandom |
| 1652 | * device, the get_random_bytes function, and the get_random_{u32,u64,int,long} |
| 1653 | * family of functions. Using any of these functions without first calling |
| 1654 | * this function forfeits the guarantee of security. |
| 1655 | * |
| 1656 | * Returns: 0 if the urandom pool has been seeded. |
| 1657 | * -ERESTARTSYS if the function was interrupted by a signal. |
| 1658 | */ |
| 1659 | int wait_for_random_bytes(void) |
| 1660 | { |
| 1661 | if (likely(crng_ready())) |
| 1662 | return 0; |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1663 | |
| 1664 | do { |
| 1665 | int ret; |
| 1666 | ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ); |
| 1667 | if (ret) |
| 1668 | return ret > 0 ? 0 : ret; |
| 1669 | |
| 1670 | try_to_generate_entropy(); |
| 1671 | } while (!crng_ready()); |
| 1672 | |
| 1673 | return 0; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1674 | } |
| 1675 | EXPORT_SYMBOL(wait_for_random_bytes); |
| 1676 | |
| 1677 | /* |
| 1678 | * Returns whether or not the urandom pool has been seeded and thus guaranteed |
| 1679 | * to supply cryptographically secure random numbers. This applies to: the |
| 1680 | * /dev/urandom device, the get_random_bytes function, and the get_random_{u32, |
| 1681 | * ,u64,int,long} family of functions. |
| 1682 | * |
| 1683 | * Returns: true if the urandom pool has been seeded. |
| 1684 | * false if the urandom pool has not been seeded. |
| 1685 | */ |
| 1686 | bool rng_is_initialized(void) |
| 1687 | { |
| 1688 | return crng_ready(); |
| 1689 | } |
| 1690 | EXPORT_SYMBOL(rng_is_initialized); |
| 1691 | |
| 1692 | /* |
| 1693 | * Add a callback function that will be invoked when the nonblocking |
| 1694 | * pool is initialised. |
| 1695 | * |
| 1696 | * returns: 0 if callback is successfully added |
| 1697 | * -EALREADY if pool is already initialised (callback not called) |
| 1698 | * -ENOENT if module for callback is not alive |
| 1699 | */ |
| 1700 | int add_random_ready_callback(struct random_ready_callback *rdy) |
| 1701 | { |
| 1702 | struct module *owner; |
| 1703 | unsigned long flags; |
| 1704 | int err = -EALREADY; |
| 1705 | |
| 1706 | if (crng_ready()) |
| 1707 | return err; |
| 1708 | |
| 1709 | owner = rdy->owner; |
| 1710 | if (!try_module_get(owner)) |
| 1711 | return -ENOENT; |
| 1712 | |
| 1713 | spin_lock_irqsave(&random_ready_list_lock, flags); |
| 1714 | if (crng_ready()) |
| 1715 | goto out; |
| 1716 | |
| 1717 | owner = NULL; |
| 1718 | |
| 1719 | list_add(&rdy->list, &random_ready_list); |
| 1720 | err = 0; |
| 1721 | |
| 1722 | out: |
| 1723 | spin_unlock_irqrestore(&random_ready_list_lock, flags); |
| 1724 | |
| 1725 | module_put(owner); |
| 1726 | |
| 1727 | return err; |
| 1728 | } |
| 1729 | EXPORT_SYMBOL(add_random_ready_callback); |
| 1730 | |
| 1731 | /* |
| 1732 | * Delete a previously registered readiness callback function. |
| 1733 | */ |
| 1734 | void del_random_ready_callback(struct random_ready_callback *rdy) |
| 1735 | { |
| 1736 | unsigned long flags; |
| 1737 | struct module *owner = NULL; |
| 1738 | |
| 1739 | spin_lock_irqsave(&random_ready_list_lock, flags); |
| 1740 | if (!list_empty(&rdy->list)) { |
| 1741 | list_del_init(&rdy->list); |
| 1742 | owner = rdy->owner; |
| 1743 | } |
| 1744 | spin_unlock_irqrestore(&random_ready_list_lock, flags); |
| 1745 | |
| 1746 | module_put(owner); |
| 1747 | } |
| 1748 | EXPORT_SYMBOL(del_random_ready_callback); |
| 1749 | |
| 1750 | /* |
| 1751 | * This function will use the architecture-specific hardware random |
| 1752 | * number generator if it is available. The arch-specific hw RNG will |
| 1753 | * almost certainly be faster than what we can do in software, but it |
| 1754 | * is impossible to verify that it is implemented securely (as |
| 1755 | * opposed, to, say, the AES encryption of a sequence number using a |
| 1756 | * key known by the NSA). So it's useful if we need the speed, but |
| 1757 | * only if we're willing to trust the hardware manufacturer not to |
| 1758 | * have put in a back door. |
| 1759 | * |
| 1760 | * Return number of bytes filled in. |
| 1761 | */ |
| 1762 | int __must_check get_random_bytes_arch(void *buf, int nbytes) |
| 1763 | { |
| 1764 | int left = nbytes; |
| 1765 | char *p = buf; |
| 1766 | |
| 1767 | trace_get_random_bytes_arch(left, _RET_IP_); |
| 1768 | while (left) { |
| 1769 | unsigned long v; |
| 1770 | int chunk = min_t(int, left, sizeof(unsigned long)); |
| 1771 | |
| 1772 | if (!arch_get_random_long(&v)) |
| 1773 | break; |
| 1774 | |
| 1775 | memcpy(p, &v, chunk); |
| 1776 | p += chunk; |
| 1777 | left -= chunk; |
| 1778 | } |
| 1779 | |
| 1780 | return nbytes - left; |
| 1781 | } |
| 1782 | EXPORT_SYMBOL(get_random_bytes_arch); |
| 1783 | |
| 1784 | /* |
| 1785 | * init_std_data - initialize pool with system data |
| 1786 | * |
| 1787 | * @r: pool to initialize |
| 1788 | * |
| 1789 | * This function clears the pool's entropy count and mixes some system |
| 1790 | * data into the pool to prepare it for use. The pool is not cleared |
| 1791 | * as that can only decrease the entropy in the pool. |
| 1792 | */ |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1793 | static void __init init_std_data(struct entropy_store *r) |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1794 | { |
| 1795 | int i; |
| 1796 | ktime_t now = ktime_get_real(); |
| 1797 | unsigned long rv; |
| 1798 | |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1799 | mix_pool_bytes(r, &now, sizeof(now)); |
| 1800 | for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) { |
| 1801 | if (!arch_get_random_seed_long(&rv) && |
| 1802 | !arch_get_random_long(&rv)) |
| 1803 | rv = random_get_entropy(); |
| 1804 | mix_pool_bytes(r, &rv, sizeof(rv)); |
| 1805 | } |
| 1806 | mix_pool_bytes(r, utsname(), sizeof(*(utsname()))); |
| 1807 | } |
| 1808 | |
| 1809 | /* |
| 1810 | * Note that setup_arch() may call add_device_randomness() |
| 1811 | * long before we get here. This allows seeding of the pools |
| 1812 | * with some platform dependent data very early in the boot |
| 1813 | * process. But it limits our options here. We must use |
| 1814 | * statically allocated structures that already have all |
| 1815 | * initializations complete at compile time. We should also |
| 1816 | * take care not to overwrite the precious per platform data |
| 1817 | * we were given. |
| 1818 | */ |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 1819 | int __init rand_initialize(void) |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1820 | { |
| 1821 | init_std_data(&input_pool); |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1822 | if (crng_need_final_init) |
| 1823 | crng_finalize_init(&primary_crng); |
| 1824 | crng_initialize_primary(&primary_crng); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1825 | crng_global_init_time = jiffies; |
| 1826 | if (ratelimit_disable) { |
| 1827 | urandom_warning.interval = 0; |
| 1828 | unseeded_warning.interval = 0; |
| 1829 | } |
| 1830 | return 0; |
| 1831 | } |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1832 | |
| 1833 | #ifdef CONFIG_BLOCK |
| 1834 | void rand_initialize_disk(struct gendisk *disk) |
| 1835 | { |
| 1836 | struct timer_rand_state *state; |
| 1837 | |
| 1838 | /* |
| 1839 | * If kzalloc returns null, we just won't use that entropy |
| 1840 | * source. |
| 1841 | */ |
| 1842 | state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
| 1843 | if (state) { |
| 1844 | state->last_time = INITIAL_JIFFIES; |
| 1845 | disk->random = state; |
| 1846 | } |
| 1847 | } |
| 1848 | #endif |
| 1849 | |
| 1850 | static ssize_t |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1851 | urandom_read_nowarn(struct file *file, char __user *buf, size_t nbytes, |
| 1852 | loff_t *ppos) |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1853 | { |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1854 | int ret; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1855 | |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1856 | nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3)); |
| 1857 | ret = extract_crng_user(buf, nbytes); |
| 1858 | trace_urandom_read(8 * nbytes, 0, ENTROPY_BITS(&input_pool)); |
| 1859 | return ret; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1860 | } |
| 1861 | |
| 1862 | static ssize_t |
| 1863 | urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) |
| 1864 | { |
| 1865 | unsigned long flags; |
| 1866 | static int maxwarn = 10; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1867 | |
| 1868 | if (!crng_ready() && maxwarn > 0) { |
| 1869 | maxwarn--; |
| 1870 | if (__ratelimit(&urandom_warning)) |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1871 | pr_notice("%s: uninitialized urandom read (%zd bytes read)\n", |
| 1872 | current->comm, nbytes); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1873 | spin_lock_irqsave(&primary_crng.lock, flags); |
| 1874 | crng_init_cnt = 0; |
| 1875 | spin_unlock_irqrestore(&primary_crng.lock, flags); |
| 1876 | } |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1877 | |
| 1878 | return urandom_read_nowarn(file, buf, nbytes, ppos); |
| 1879 | } |
| 1880 | |
| 1881 | static ssize_t |
| 1882 | random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) |
| 1883 | { |
| 1884 | int ret; |
| 1885 | |
| 1886 | ret = wait_for_random_bytes(); |
| 1887 | if (ret != 0) |
| 1888 | return ret; |
| 1889 | return urandom_read_nowarn(file, buf, nbytes, ppos); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1890 | } |
| 1891 | |
| 1892 | static __poll_t |
| 1893 | random_poll(struct file *file, poll_table * wait) |
| 1894 | { |
| 1895 | __poll_t mask; |
| 1896 | |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1897 | poll_wait(file, &crng_init_wait, wait); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1898 | poll_wait(file, &random_write_wait, wait); |
| 1899 | mask = 0; |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1900 | if (crng_ready()) |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1901 | mask |= EPOLLIN | EPOLLRDNORM; |
| 1902 | if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits) |
| 1903 | mask |= EPOLLOUT | EPOLLWRNORM; |
| 1904 | return mask; |
| 1905 | } |
| 1906 | |
| 1907 | static int |
| 1908 | write_pool(struct entropy_store *r, const char __user *buffer, size_t count) |
| 1909 | { |
| 1910 | size_t bytes; |
| 1911 | __u32 t, buf[16]; |
| 1912 | const char __user *p = buffer; |
| 1913 | |
| 1914 | while (count > 0) { |
| 1915 | int b, i = 0; |
| 1916 | |
| 1917 | bytes = min(count, sizeof(buf)); |
| 1918 | if (copy_from_user(&buf, p, bytes)) |
| 1919 | return -EFAULT; |
| 1920 | |
| 1921 | for (b = bytes ; b > 0 ; b -= sizeof(__u32), i++) { |
| 1922 | if (!arch_get_random_int(&t)) |
| 1923 | break; |
| 1924 | buf[i] ^= t; |
| 1925 | } |
| 1926 | |
| 1927 | count -= bytes; |
| 1928 | p += bytes; |
| 1929 | |
| 1930 | mix_pool_bytes(r, buf, bytes); |
| 1931 | cond_resched(); |
| 1932 | } |
| 1933 | |
| 1934 | return 0; |
| 1935 | } |
| 1936 | |
| 1937 | static ssize_t random_write(struct file *file, const char __user *buffer, |
| 1938 | size_t count, loff_t *ppos) |
| 1939 | { |
| 1940 | size_t ret; |
| 1941 | |
| 1942 | ret = write_pool(&input_pool, buffer, count); |
| 1943 | if (ret) |
| 1944 | return ret; |
| 1945 | |
| 1946 | return (ssize_t)count; |
| 1947 | } |
| 1948 | |
| 1949 | static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) |
| 1950 | { |
| 1951 | int size, ent_count; |
| 1952 | int __user *p = (int __user *)arg; |
| 1953 | int retval; |
| 1954 | |
| 1955 | switch (cmd) { |
| 1956 | case RNDGETENTCNT: |
| 1957 | /* inherently racy, no point locking */ |
| 1958 | ent_count = ENTROPY_BITS(&input_pool); |
| 1959 | if (put_user(ent_count, p)) |
| 1960 | return -EFAULT; |
| 1961 | return 0; |
| 1962 | case RNDADDTOENTCNT: |
| 1963 | if (!capable(CAP_SYS_ADMIN)) |
| 1964 | return -EPERM; |
| 1965 | if (get_user(ent_count, p)) |
| 1966 | return -EFAULT; |
| 1967 | return credit_entropy_bits_safe(&input_pool, ent_count); |
| 1968 | case RNDADDENTROPY: |
| 1969 | if (!capable(CAP_SYS_ADMIN)) |
| 1970 | return -EPERM; |
| 1971 | if (get_user(ent_count, p++)) |
| 1972 | return -EFAULT; |
| 1973 | if (ent_count < 0) |
| 1974 | return -EINVAL; |
| 1975 | if (get_user(size, p++)) |
| 1976 | return -EFAULT; |
| 1977 | retval = write_pool(&input_pool, (const char __user *)p, |
| 1978 | size); |
| 1979 | if (retval < 0) |
| 1980 | return retval; |
| 1981 | return credit_entropy_bits_safe(&input_pool, ent_count); |
| 1982 | case RNDZAPENTCNT: |
| 1983 | case RNDCLEARPOOL: |
| 1984 | /* |
| 1985 | * Clear the entropy pool counters. We no longer clear |
| 1986 | * the entropy pool, as that's silly. |
| 1987 | */ |
| 1988 | if (!capable(CAP_SYS_ADMIN)) |
| 1989 | return -EPERM; |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1990 | if (xchg(&input_pool.entropy_count, 0) && random_write_wakeup_bits) { |
| 1991 | wake_up_interruptible(&random_write_wait); |
| 1992 | kill_fasync(&fasync, SIGIO, POLL_OUT); |
| 1993 | } |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1994 | return 0; |
| 1995 | case RNDRESEEDCRNG: |
| 1996 | if (!capable(CAP_SYS_ADMIN)) |
| 1997 | return -EPERM; |
| 1998 | if (crng_init < 2) |
| 1999 | return -ENODATA; |
Olivier Deprez | 0e64123 | 2021-09-23 10:07:05 +0200 | [diff] [blame] | 2000 | crng_reseed(&primary_crng, &input_pool); |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 2001 | WRITE_ONCE(crng_global_init_time, jiffies - 1); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2002 | return 0; |
| 2003 | default: |
| 2004 | return -EINVAL; |
| 2005 | } |
| 2006 | } |
| 2007 | |
| 2008 | static int random_fasync(int fd, struct file *filp, int on) |
| 2009 | { |
| 2010 | return fasync_helper(fd, filp, on, &fasync); |
| 2011 | } |
| 2012 | |
| 2013 | const struct file_operations random_fops = { |
| 2014 | .read = random_read, |
| 2015 | .write = random_write, |
| 2016 | .poll = random_poll, |
| 2017 | .unlocked_ioctl = random_ioctl, |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 2018 | .compat_ioctl = compat_ptr_ioctl, |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2019 | .fasync = random_fasync, |
| 2020 | .llseek = noop_llseek, |
| 2021 | }; |
| 2022 | |
| 2023 | const struct file_operations urandom_fops = { |
| 2024 | .read = urandom_read, |
| 2025 | .write = random_write, |
| 2026 | .unlocked_ioctl = random_ioctl, |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 2027 | .compat_ioctl = compat_ptr_ioctl, |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2028 | .fasync = random_fasync, |
| 2029 | .llseek = noop_llseek, |
| 2030 | }; |
| 2031 | |
| 2032 | SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, |
| 2033 | unsigned int, flags) |
| 2034 | { |
| 2035 | int ret; |
| 2036 | |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 2037 | if (flags & ~(GRND_NONBLOCK|GRND_RANDOM|GRND_INSECURE)) |
| 2038 | return -EINVAL; |
| 2039 | |
| 2040 | /* |
| 2041 | * Requesting insecure and blocking randomness at the same time makes |
| 2042 | * no sense. |
| 2043 | */ |
| 2044 | if ((flags & (GRND_INSECURE|GRND_RANDOM)) == (GRND_INSECURE|GRND_RANDOM)) |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2045 | return -EINVAL; |
| 2046 | |
| 2047 | if (count > INT_MAX) |
| 2048 | count = INT_MAX; |
| 2049 | |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 2050 | if (!(flags & GRND_INSECURE) && !crng_ready()) { |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2051 | if (flags & GRND_NONBLOCK) |
| 2052 | return -EAGAIN; |
| 2053 | ret = wait_for_random_bytes(); |
| 2054 | if (unlikely(ret)) |
| 2055 | return ret; |
| 2056 | } |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 2057 | return urandom_read_nowarn(NULL, buf, count, NULL); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2058 | } |
| 2059 | |
| 2060 | /******************************************************************** |
| 2061 | * |
| 2062 | * Sysctl interface |
| 2063 | * |
| 2064 | ********************************************************************/ |
| 2065 | |
| 2066 | #ifdef CONFIG_SYSCTL |
| 2067 | |
| 2068 | #include <linux/sysctl.h> |
| 2069 | |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 2070 | static int min_write_thresh; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2071 | static int max_write_thresh = INPUT_POOL_WORDS * 32; |
| 2072 | static int random_min_urandom_seed = 60; |
| 2073 | static char sysctl_bootid[16]; |
| 2074 | |
| 2075 | /* |
| 2076 | * This function is used to return both the bootid UUID, and random |
| 2077 | * UUID. The difference is in whether table->data is NULL; if it is, |
| 2078 | * then a new UUID is generated and returned to the user. |
| 2079 | * |
| 2080 | * If the user accesses this via the proc interface, the UUID will be |
| 2081 | * returned as an ASCII string in the standard UUID format; if via the |
| 2082 | * sysctl system call, as 16 bytes of binary data. |
| 2083 | */ |
| 2084 | static int proc_do_uuid(struct ctl_table *table, int write, |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 2085 | void *buffer, size_t *lenp, loff_t *ppos) |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2086 | { |
| 2087 | struct ctl_table fake_table; |
| 2088 | unsigned char buf[64], tmp_uuid[16], *uuid; |
| 2089 | |
| 2090 | uuid = table->data; |
| 2091 | if (!uuid) { |
| 2092 | uuid = tmp_uuid; |
| 2093 | generate_random_uuid(uuid); |
| 2094 | } else { |
| 2095 | static DEFINE_SPINLOCK(bootid_spinlock); |
| 2096 | |
| 2097 | spin_lock(&bootid_spinlock); |
| 2098 | if (!uuid[8]) |
| 2099 | generate_random_uuid(uuid); |
| 2100 | spin_unlock(&bootid_spinlock); |
| 2101 | } |
| 2102 | |
| 2103 | sprintf(buf, "%pU", uuid); |
| 2104 | |
| 2105 | fake_table.data = buf; |
| 2106 | fake_table.maxlen = sizeof(buf); |
| 2107 | |
| 2108 | return proc_dostring(&fake_table, write, buffer, lenp, ppos); |
| 2109 | } |
| 2110 | |
| 2111 | /* |
| 2112 | * Return entropy available scaled to integral bits |
| 2113 | */ |
| 2114 | static int proc_do_entropy(struct ctl_table *table, int write, |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 2115 | void *buffer, size_t *lenp, loff_t *ppos) |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2116 | { |
| 2117 | struct ctl_table fake_table; |
| 2118 | int entropy_count; |
| 2119 | |
| 2120 | entropy_count = *(int *)table->data >> ENTROPY_SHIFT; |
| 2121 | |
| 2122 | fake_table.data = &entropy_count; |
| 2123 | fake_table.maxlen = sizeof(entropy_count); |
| 2124 | |
| 2125 | return proc_dointvec(&fake_table, write, buffer, lenp, ppos); |
| 2126 | } |
| 2127 | |
| 2128 | static int sysctl_poolsize = INPUT_POOL_WORDS * 32; |
| 2129 | extern struct ctl_table random_table[]; |
| 2130 | struct ctl_table random_table[] = { |
| 2131 | { |
| 2132 | .procname = "poolsize", |
| 2133 | .data = &sysctl_poolsize, |
| 2134 | .maxlen = sizeof(int), |
| 2135 | .mode = 0444, |
| 2136 | .proc_handler = proc_dointvec, |
| 2137 | }, |
| 2138 | { |
| 2139 | .procname = "entropy_avail", |
| 2140 | .maxlen = sizeof(int), |
| 2141 | .mode = 0444, |
| 2142 | .proc_handler = proc_do_entropy, |
| 2143 | .data = &input_pool.entropy_count, |
| 2144 | }, |
| 2145 | { |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2146 | .procname = "write_wakeup_threshold", |
| 2147 | .data = &random_write_wakeup_bits, |
| 2148 | .maxlen = sizeof(int), |
| 2149 | .mode = 0644, |
| 2150 | .proc_handler = proc_dointvec_minmax, |
| 2151 | .extra1 = &min_write_thresh, |
| 2152 | .extra2 = &max_write_thresh, |
| 2153 | }, |
| 2154 | { |
| 2155 | .procname = "urandom_min_reseed_secs", |
| 2156 | .data = &random_min_urandom_seed, |
| 2157 | .maxlen = sizeof(int), |
| 2158 | .mode = 0644, |
| 2159 | .proc_handler = proc_dointvec, |
| 2160 | }, |
| 2161 | { |
| 2162 | .procname = "boot_id", |
| 2163 | .data = &sysctl_bootid, |
| 2164 | .maxlen = 16, |
| 2165 | .mode = 0444, |
| 2166 | .proc_handler = proc_do_uuid, |
| 2167 | }, |
| 2168 | { |
| 2169 | .procname = "uuid", |
| 2170 | .maxlen = 16, |
| 2171 | .mode = 0444, |
| 2172 | .proc_handler = proc_do_uuid, |
| 2173 | }, |
| 2174 | #ifdef ADD_INTERRUPT_BENCH |
| 2175 | { |
| 2176 | .procname = "add_interrupt_avg_cycles", |
| 2177 | .data = &avg_cycles, |
| 2178 | .maxlen = sizeof(avg_cycles), |
| 2179 | .mode = 0444, |
| 2180 | .proc_handler = proc_doulongvec_minmax, |
| 2181 | }, |
| 2182 | { |
| 2183 | .procname = "add_interrupt_avg_deviation", |
| 2184 | .data = &avg_deviation, |
| 2185 | .maxlen = sizeof(avg_deviation), |
| 2186 | .mode = 0444, |
| 2187 | .proc_handler = proc_doulongvec_minmax, |
| 2188 | }, |
| 2189 | #endif |
| 2190 | { } |
| 2191 | }; |
| 2192 | #endif /* CONFIG_SYSCTL */ |
| 2193 | |
| 2194 | struct batched_entropy { |
| 2195 | union { |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 2196 | u64 entropy_u64[CHACHA_BLOCK_SIZE / sizeof(u64)]; |
| 2197 | u32 entropy_u32[CHACHA_BLOCK_SIZE / sizeof(u32)]; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2198 | }; |
| 2199 | unsigned int position; |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 2200 | spinlock_t batch_lock; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2201 | }; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2202 | |
| 2203 | /* |
| 2204 | * Get a random word for internal kernel use only. The quality of the random |
Olivier Deprez | 0e64123 | 2021-09-23 10:07:05 +0200 | [diff] [blame] | 2205 | * number is good as /dev/urandom, but there is no backtrack protection, with |
| 2206 | * the goal of being quite fast and not depleting entropy. In order to ensure |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2207 | * that the randomness provided by this function is okay, the function |
Olivier Deprez | 0e64123 | 2021-09-23 10:07:05 +0200 | [diff] [blame] | 2208 | * wait_for_random_bytes() should be called and return 0 at least once at any |
| 2209 | * point prior. |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2210 | */ |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 2211 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = { |
| 2212 | .batch_lock = __SPIN_LOCK_UNLOCKED(batched_entropy_u64.lock), |
| 2213 | }; |
| 2214 | |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2215 | u64 get_random_u64(void) |
| 2216 | { |
| 2217 | u64 ret; |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 2218 | unsigned long flags; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2219 | struct batched_entropy *batch; |
| 2220 | static void *previous; |
| 2221 | |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2222 | warn_unseeded_randomness(&previous); |
| 2223 | |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 2224 | batch = raw_cpu_ptr(&batched_entropy_u64); |
| 2225 | spin_lock_irqsave(&batch->batch_lock, flags); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2226 | if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) { |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 2227 | extract_crng((u8 *)batch->entropy_u64); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2228 | batch->position = 0; |
| 2229 | } |
| 2230 | ret = batch->entropy_u64[batch->position++]; |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 2231 | spin_unlock_irqrestore(&batch->batch_lock, flags); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2232 | return ret; |
| 2233 | } |
| 2234 | EXPORT_SYMBOL(get_random_u64); |
| 2235 | |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 2236 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = { |
| 2237 | .batch_lock = __SPIN_LOCK_UNLOCKED(batched_entropy_u32.lock), |
| 2238 | }; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2239 | u32 get_random_u32(void) |
| 2240 | { |
| 2241 | u32 ret; |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 2242 | unsigned long flags; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2243 | struct batched_entropy *batch; |
| 2244 | static void *previous; |
| 2245 | |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2246 | warn_unseeded_randomness(&previous); |
| 2247 | |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 2248 | batch = raw_cpu_ptr(&batched_entropy_u32); |
| 2249 | spin_lock_irqsave(&batch->batch_lock, flags); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2250 | if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) { |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 2251 | extract_crng((u8 *)batch->entropy_u32); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2252 | batch->position = 0; |
| 2253 | } |
| 2254 | ret = batch->entropy_u32[batch->position++]; |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 2255 | spin_unlock_irqrestore(&batch->batch_lock, flags); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2256 | return ret; |
| 2257 | } |
| 2258 | EXPORT_SYMBOL(get_random_u32); |
| 2259 | |
| 2260 | /* It's important to invalidate all potential batched entropy that might |
| 2261 | * be stored before the crng is initialized, which we can do lazily by |
| 2262 | * simply resetting the counter to zero so that it's re-extracted on the |
| 2263 | * next usage. */ |
| 2264 | static void invalidate_batched_entropy(void) |
| 2265 | { |
| 2266 | int cpu; |
| 2267 | unsigned long flags; |
| 2268 | |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2269 | for_each_possible_cpu (cpu) { |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 2270 | struct batched_entropy *batched_entropy; |
| 2271 | |
| 2272 | batched_entropy = per_cpu_ptr(&batched_entropy_u32, cpu); |
| 2273 | spin_lock_irqsave(&batched_entropy->batch_lock, flags); |
| 2274 | batched_entropy->position = 0; |
| 2275 | spin_unlock(&batched_entropy->batch_lock); |
| 2276 | |
| 2277 | batched_entropy = per_cpu_ptr(&batched_entropy_u64, cpu); |
| 2278 | spin_lock(&batched_entropy->batch_lock); |
| 2279 | batched_entropy->position = 0; |
| 2280 | spin_unlock_irqrestore(&batched_entropy->batch_lock, flags); |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2281 | } |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2282 | } |
| 2283 | |
| 2284 | /** |
| 2285 | * randomize_page - Generate a random, page aligned address |
| 2286 | * @start: The smallest acceptable address the caller will take. |
| 2287 | * @range: The size of the area, starting at @start, within which the |
| 2288 | * random address must fall. |
| 2289 | * |
| 2290 | * If @start + @range would overflow, @range is capped. |
| 2291 | * |
| 2292 | * NOTE: Historical use of randomize_range, which this replaces, presumed that |
| 2293 | * @start was already page aligned. We now align it regardless. |
| 2294 | * |
| 2295 | * Return: A page aligned address within [start, start + range). On error, |
| 2296 | * @start is returned. |
| 2297 | */ |
| 2298 | unsigned long |
| 2299 | randomize_page(unsigned long start, unsigned long range) |
| 2300 | { |
| 2301 | if (!PAGE_ALIGNED(start)) { |
| 2302 | range -= PAGE_ALIGN(start) - start; |
| 2303 | start = PAGE_ALIGN(start); |
| 2304 | } |
| 2305 | |
| 2306 | if (start > ULONG_MAX - range) |
| 2307 | range = ULONG_MAX - start; |
| 2308 | |
| 2309 | range >>= PAGE_SHIFT; |
| 2310 | |
| 2311 | if (range == 0) |
| 2312 | return start; |
| 2313 | |
| 2314 | return start + (get_random_long() % range << PAGE_SHIFT); |
| 2315 | } |
| 2316 | |
| 2317 | /* Interface for in-kernel drivers of true hardware RNGs. |
| 2318 | * Those devices may produce endless random bits and will be throttled |
| 2319 | * when our pool is full. |
| 2320 | */ |
| 2321 | void add_hwgenerator_randomness(const char *buffer, size_t count, |
| 2322 | size_t entropy) |
| 2323 | { |
| 2324 | struct entropy_store *poolp = &input_pool; |
| 2325 | |
| 2326 | if (unlikely(crng_init == 0)) { |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 2327 | size_t ret = crng_fast_load(buffer, count); |
| 2328 | count -= ret; |
| 2329 | buffer += ret; |
| 2330 | if (!count || crng_init == 0) |
| 2331 | return; |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2332 | } |
| 2333 | |
| 2334 | /* Suspend writing if we're above the trickle threshold. |
| 2335 | * We'll be woken up again once below random_write_wakeup_thresh, |
| 2336 | * or when the calling thread is about to terminate. |
| 2337 | */ |
Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 2338 | wait_event_interruptible(random_write_wait, |
| 2339 | !system_wq || kthread_should_stop() || |
Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 2340 | ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits); |
| 2341 | mix_pool_bytes(poolp, buffer, count); |
| 2342 | credit_entropy_bits(poolp, entropy); |
| 2343 | } |
| 2344 | EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); |
David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame] | 2345 | |
| 2346 | /* Handle random seed passed by bootloader. |
| 2347 | * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise |
| 2348 | * it would be regarded as device data. |
| 2349 | * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER. |
| 2350 | */ |
| 2351 | void add_bootloader_randomness(const void *buf, unsigned int size) |
| 2352 | { |
| 2353 | if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER)) |
| 2354 | add_hwgenerator_randomness(buf, size, size * 8); |
| 2355 | else |
| 2356 | add_device_randomness(buf, size); |
| 2357 | } |
| 2358 | EXPORT_SYMBOL_GPL(add_bootloader_randomness); |