v4.19.13 snapshot.
diff --git a/kernel/acct.c b/kernel/acct.c
new file mode 100644
index 0000000..addf773
--- /dev/null
+++ b/kernel/acct.c
@@ -0,0 +1,606 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/kernel/acct.c
+ *
+ * BSD Process Accounting for Linux
+ *
+ * Author: Marco van Wieringen <mvw@planets.elm.net>
+ *
+ * Some code based on ideas and code from:
+ * Thomas K. Dyas <tdyas@eden.rutgers.edu>
+ *
+ * This file implements BSD-style process accounting. Whenever any
+ * process exits, an accounting record of type "struct acct" is
+ * written to the file specified with the acct() system call. It is
+ * up to user-level programs to do useful things with the accounting
+ * log. The kernel just provides the raw accounting information.
+ *
+ * (C) Copyright 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V.
+ *
+ * Plugged two leaks. 1) It didn't return acct_file into the free_filps if
+ * the file happened to be read-only. 2) If the accounting was suspended
+ * due to the lack of space it happily allowed to reopen it and completely
+ * lost the old acct_file. 3/10/98, Al Viro.
+ *
+ * Now we silently close acct_file on attempt to reopen. Cleaned sys_acct().
+ * XTerms and EMACS are manifestations of pure evil. 21/10/98, AV.
+ *
+ * Fixed a nasty interaction with with sys_umount(). If the accointing
+ * was suspeneded we failed to stop it on umount(). Messy.
+ * Another one: remount to readonly didn't stop accounting.
+ * Question: what should we do if we have CAP_SYS_ADMIN but not
+ * CAP_SYS_PACCT? Current code does the following: umount returns -EBUSY
+ * unless we are messing with the root. In that case we are getting a
+ * real mess with do_remount_sb(). 9/11/98, AV.
+ *
+ * Fixed a bunch of races (and pair of leaks). Probably not the best way,
+ * but this one obviously doesn't introduce deadlocks. Later. BTW, found
+ * one race (and leak) in BSD implementation.
+ * OK, that's better. ANOTHER race and leak in BSD variant. There always
+ * is one more bug... 10/11/98, AV.
+ *
+ * Oh, fsck... Oopsable SMP race in do_process_acct() - we must hold
+ * ->mmap_sem to walk the vma list of current->mm. Nasty, since it leaks
+ * a struct file opened for write. Fixed. 2/6/2000, AV.
+ */
+
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/acct.h>
+#include <linux/capability.h>
+#include <linux/file.h>
+#include <linux/tty.h>
+#include <linux/security.h>
+#include <linux/vfs.h>
+#include <linux/jiffies.h>
+#include <linux/times.h>
+#include <linux/syscalls.h>
+#include <linux/mount.h>
+#include <linux/uaccess.h>
+#include <linux/sched/cputime.h>
+
+#include <asm/div64.h>
+#include <linux/blkdev.h> /* sector_div */
+#include <linux/pid_namespace.h>
+#include <linux/fs_pin.h>
+
+/*
+ * These constants control the amount of freespace that suspend and
+ * resume the process accounting system, and the time delay between
+ * each check.
+ * Turned into sysctl-controllable parameters. AV, 12/11/98
+ */
+
+int acct_parm[3] = {4, 2, 30};
+#define RESUME (acct_parm[0]) /* >foo% free space - resume */
+#define SUSPEND (acct_parm[1]) /* <foo% free space - suspend */
+#define ACCT_TIMEOUT (acct_parm[2]) /* foo second timeout between checks */
+
+/*
+ * External references and all of the globals.
+ */
+
+struct bsd_acct_struct {
+ struct fs_pin pin;
+ atomic_long_t count;
+ struct rcu_head rcu;
+ struct mutex lock;
+ int active;
+ unsigned long needcheck;
+ struct file *file;
+ struct pid_namespace *ns;
+ struct work_struct work;
+ struct completion done;
+};
+
+static void do_acct_process(struct bsd_acct_struct *acct);
+
+/*
+ * Check the amount of free space and suspend/resume accordingly.
+ */
+static int check_free_space(struct bsd_acct_struct *acct)
+{
+ struct kstatfs sbuf;
+
+ if (time_is_after_jiffies(acct->needcheck))
+ goto out;
+
+ /* May block */
+ if (vfs_statfs(&acct->file->f_path, &sbuf))
+ goto out;
+
+ if (acct->active) {
+ u64 suspend = sbuf.f_blocks * SUSPEND;
+ do_div(suspend, 100);
+ if (sbuf.f_bavail <= suspend) {
+ acct->active = 0;
+ pr_info("Process accounting paused\n");
+ }
+ } else {
+ u64 resume = sbuf.f_blocks * RESUME;
+ do_div(resume, 100);
+ if (sbuf.f_bavail >= resume) {
+ acct->active = 1;
+ pr_info("Process accounting resumed\n");
+ }
+ }
+
+ acct->needcheck = jiffies + ACCT_TIMEOUT*HZ;
+out:
+ return acct->active;
+}
+
+static void acct_put(struct bsd_acct_struct *p)
+{
+ if (atomic_long_dec_and_test(&p->count))
+ kfree_rcu(p, rcu);
+}
+
+static inline struct bsd_acct_struct *to_acct(struct fs_pin *p)
+{
+ return p ? container_of(p, struct bsd_acct_struct, pin) : NULL;
+}
+
+static struct bsd_acct_struct *acct_get(struct pid_namespace *ns)
+{
+ struct bsd_acct_struct *res;
+again:
+ smp_rmb();
+ rcu_read_lock();
+ res = to_acct(READ_ONCE(ns->bacct));
+ if (!res) {
+ rcu_read_unlock();
+ return NULL;
+ }
+ if (!atomic_long_inc_not_zero(&res->count)) {
+ rcu_read_unlock();
+ cpu_relax();
+ goto again;
+ }
+ rcu_read_unlock();
+ mutex_lock(&res->lock);
+ if (res != to_acct(READ_ONCE(ns->bacct))) {
+ mutex_unlock(&res->lock);
+ acct_put(res);
+ goto again;
+ }
+ return res;
+}
+
+static void acct_pin_kill(struct fs_pin *pin)
+{
+ struct bsd_acct_struct *acct = to_acct(pin);
+ mutex_lock(&acct->lock);
+ do_acct_process(acct);
+ schedule_work(&acct->work);
+ wait_for_completion(&acct->done);
+ cmpxchg(&acct->ns->bacct, pin, NULL);
+ mutex_unlock(&acct->lock);
+ pin_remove(pin);
+ acct_put(acct);
+}
+
+static void close_work(struct work_struct *work)
+{
+ struct bsd_acct_struct *acct = container_of(work, struct bsd_acct_struct, work);
+ struct file *file = acct->file;
+ if (file->f_op->flush)
+ file->f_op->flush(file, NULL);
+ __fput_sync(file);
+ complete(&acct->done);
+}
+
+static int acct_on(struct filename *pathname)
+{
+ struct file *file;
+ struct vfsmount *mnt, *internal;
+ struct pid_namespace *ns = task_active_pid_ns(current);
+ struct bsd_acct_struct *acct;
+ struct fs_pin *old;
+ int err;
+
+ acct = kzalloc(sizeof(struct bsd_acct_struct), GFP_KERNEL);
+ if (!acct)
+ return -ENOMEM;
+
+ /* Difference from BSD - they don't do O_APPEND */
+ file = file_open_name(pathname, O_WRONLY|O_APPEND|O_LARGEFILE, 0);
+ if (IS_ERR(file)) {
+ kfree(acct);
+ return PTR_ERR(file);
+ }
+
+ if (!S_ISREG(file_inode(file)->i_mode)) {
+ kfree(acct);
+ filp_close(file, NULL);
+ return -EACCES;
+ }
+
+ if (!(file->f_mode & FMODE_CAN_WRITE)) {
+ kfree(acct);
+ filp_close(file, NULL);
+ return -EIO;
+ }
+ internal = mnt_clone_internal(&file->f_path);
+ if (IS_ERR(internal)) {
+ kfree(acct);
+ filp_close(file, NULL);
+ return PTR_ERR(internal);
+ }
+ err = mnt_want_write(internal);
+ if (err) {
+ mntput(internal);
+ kfree(acct);
+ filp_close(file, NULL);
+ return err;
+ }
+ mnt = file->f_path.mnt;
+ file->f_path.mnt = internal;
+
+ atomic_long_set(&acct->count, 1);
+ init_fs_pin(&acct->pin, acct_pin_kill);
+ acct->file = file;
+ acct->needcheck = jiffies;
+ acct->ns = ns;
+ mutex_init(&acct->lock);
+ INIT_WORK(&acct->work, close_work);
+ init_completion(&acct->done);
+ mutex_lock_nested(&acct->lock, 1); /* nobody has seen it yet */
+ pin_insert(&acct->pin, mnt);
+
+ rcu_read_lock();
+ old = xchg(&ns->bacct, &acct->pin);
+ mutex_unlock(&acct->lock);
+ pin_kill(old);
+ mnt_drop_write(mnt);
+ mntput(mnt);
+ return 0;
+}
+
+static DEFINE_MUTEX(acct_on_mutex);
+
+/**
+ * sys_acct - enable/disable process accounting
+ * @name: file name for accounting records or NULL to shutdown accounting
+ *
+ * Returns 0 for success or negative errno values for failure.
+ *
+ * sys_acct() is the only system call needed to implement process
+ * accounting. It takes the name of the file where accounting records
+ * should be written. If the filename is NULL, accounting will be
+ * shutdown.
+ */
+SYSCALL_DEFINE1(acct, const char __user *, name)
+{
+ int error = 0;
+
+ if (!capable(CAP_SYS_PACCT))
+ return -EPERM;
+
+ if (name) {
+ struct filename *tmp = getname(name);
+
+ if (IS_ERR(tmp))
+ return PTR_ERR(tmp);
+ mutex_lock(&acct_on_mutex);
+ error = acct_on(tmp);
+ mutex_unlock(&acct_on_mutex);
+ putname(tmp);
+ } else {
+ rcu_read_lock();
+ pin_kill(task_active_pid_ns(current)->bacct);
+ }
+
+ return error;
+}
+
+void acct_exit_ns(struct pid_namespace *ns)
+{
+ rcu_read_lock();
+ pin_kill(ns->bacct);
+}
+
+/*
+ * encode an unsigned long into a comp_t
+ *
+ * This routine has been adopted from the encode_comp_t() function in
+ * the kern_acct.c file of the FreeBSD operating system. The encoding
+ * is a 13-bit fraction with a 3-bit (base 8) exponent.
+ */
+
+#define MANTSIZE 13 /* 13 bit mantissa. */
+#define EXPSIZE 3 /* Base 8 (3 bit) exponent. */
+#define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */
+
+static comp_t encode_comp_t(unsigned long value)
+{
+ int exp, rnd;
+
+ exp = rnd = 0;
+ while (value > MAXFRACT) {
+ rnd = value & (1 << (EXPSIZE - 1)); /* Round up? */
+ value >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */
+ exp++;
+ }
+
+ /*
+ * If we need to round up, do it (and handle overflow correctly).
+ */
+ if (rnd && (++value > MAXFRACT)) {
+ value >>= EXPSIZE;
+ exp++;
+ }
+
+ /*
+ * Clean it up and polish it off.
+ */
+ exp <<= MANTSIZE; /* Shift the exponent into place */
+ exp += value; /* and add on the mantissa. */
+ return exp;
+}
+
+#if ACCT_VERSION == 1 || ACCT_VERSION == 2
+/*
+ * encode an u64 into a comp2_t (24 bits)
+ *
+ * Format: 5 bit base 2 exponent, 20 bits mantissa.
+ * The leading bit of the mantissa is not stored, but implied for
+ * non-zero exponents.
+ * Largest encodable value is 50 bits.
+ */
+
+#define MANTSIZE2 20 /* 20 bit mantissa. */
+#define EXPSIZE2 5 /* 5 bit base 2 exponent. */
+#define MAXFRACT2 ((1ul << MANTSIZE2) - 1) /* Maximum fractional value. */
+#define MAXEXP2 ((1 << EXPSIZE2) - 1) /* Maximum exponent. */
+
+static comp2_t encode_comp2_t(u64 value)
+{
+ int exp, rnd;
+
+ exp = (value > (MAXFRACT2>>1));
+ rnd = 0;
+ while (value > MAXFRACT2) {
+ rnd = value & 1;
+ value >>= 1;
+ exp++;
+ }
+
+ /*
+ * If we need to round up, do it (and handle overflow correctly).
+ */
+ if (rnd && (++value > MAXFRACT2)) {
+ value >>= 1;
+ exp++;
+ }
+
+ if (exp > MAXEXP2) {
+ /* Overflow. Return largest representable number instead. */
+ return (1ul << (MANTSIZE2+EXPSIZE2-1)) - 1;
+ } else {
+ return (value & (MAXFRACT2>>1)) | (exp << (MANTSIZE2-1));
+ }
+}
+#endif
+
+#if ACCT_VERSION == 3
+/*
+ * encode an u64 into a 32 bit IEEE float
+ */
+static u32 encode_float(u64 value)
+{
+ unsigned exp = 190;
+ unsigned u;
+
+ if (value == 0)
+ return 0;
+ while ((s64)value > 0) {
+ value <<= 1;
+ exp--;
+ }
+ u = (u32)(value >> 40) & 0x7fffffu;
+ return u | (exp << 23);
+}
+#endif
+
+/*
+ * Write an accounting entry for an exiting process
+ *
+ * The acct_process() call is the workhorse of the process
+ * accounting system. The struct acct is built here and then written
+ * into the accounting file. This function should only be called from
+ * do_exit() or when switching to a different output file.
+ */
+
+static void fill_ac(acct_t *ac)
+{
+ struct pacct_struct *pacct = ¤t->signal->pacct;
+ u64 elapsed, run_time;
+ struct tty_struct *tty;
+
+ /*
+ * Fill the accounting struct with the needed info as recorded
+ * by the different kernel functions.
+ */
+ memset(ac, 0, sizeof(acct_t));
+
+ ac->ac_version = ACCT_VERSION | ACCT_BYTEORDER;
+ strlcpy(ac->ac_comm, current->comm, sizeof(ac->ac_comm));
+
+ /* calculate run_time in nsec*/
+ run_time = ktime_get_ns();
+ run_time -= current->group_leader->start_time;
+ /* convert nsec -> AHZ */
+ elapsed = nsec_to_AHZ(run_time);
+#if ACCT_VERSION == 3
+ ac->ac_etime = encode_float(elapsed);
+#else
+ ac->ac_etime = encode_comp_t(elapsed < (unsigned long) -1l ?
+ (unsigned long) elapsed : (unsigned long) -1l);
+#endif
+#if ACCT_VERSION == 1 || ACCT_VERSION == 2
+ {
+ /* new enlarged etime field */
+ comp2_t etime = encode_comp2_t(elapsed);
+
+ ac->ac_etime_hi = etime >> 16;
+ ac->ac_etime_lo = (u16) etime;
+ }
+#endif
+ do_div(elapsed, AHZ);
+ ac->ac_btime = get_seconds() - elapsed;
+#if ACCT_VERSION==2
+ ac->ac_ahz = AHZ;
+#endif
+
+ spin_lock_irq(¤t->sighand->siglock);
+ tty = current->signal->tty; /* Safe as we hold the siglock */
+ ac->ac_tty = tty ? old_encode_dev(tty_devnum(tty)) : 0;
+ ac->ac_utime = encode_comp_t(nsec_to_AHZ(pacct->ac_utime));
+ ac->ac_stime = encode_comp_t(nsec_to_AHZ(pacct->ac_stime));
+ ac->ac_flag = pacct->ac_flag;
+ ac->ac_mem = encode_comp_t(pacct->ac_mem);
+ ac->ac_minflt = encode_comp_t(pacct->ac_minflt);
+ ac->ac_majflt = encode_comp_t(pacct->ac_majflt);
+ ac->ac_exitcode = pacct->ac_exitcode;
+ spin_unlock_irq(¤t->sighand->siglock);
+}
+/*
+ * do_acct_process does all actual work. Caller holds the reference to file.
+ */
+static void do_acct_process(struct bsd_acct_struct *acct)
+{
+ acct_t ac;
+ unsigned long flim;
+ const struct cred *orig_cred;
+ struct file *file = acct->file;
+
+ /*
+ * Accounting records are not subject to resource limits.
+ */
+ flim = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
+ current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
+ /* Perform file operations on behalf of whoever enabled accounting */
+ orig_cred = override_creds(file->f_cred);
+
+ /*
+ * First check to see if there is enough free_space to continue
+ * the process accounting system.
+ */
+ if (!check_free_space(acct))
+ goto out;
+
+ fill_ac(&ac);
+ /* we really need to bite the bullet and change layout */
+ ac.ac_uid = from_kuid_munged(file->f_cred->user_ns, orig_cred->uid);
+ ac.ac_gid = from_kgid_munged(file->f_cred->user_ns, orig_cred->gid);
+#if ACCT_VERSION == 1 || ACCT_VERSION == 2
+ /* backward-compatible 16 bit fields */
+ ac.ac_uid16 = ac.ac_uid;
+ ac.ac_gid16 = ac.ac_gid;
+#endif
+#if ACCT_VERSION == 3
+ {
+ struct pid_namespace *ns = acct->ns;
+
+ ac.ac_pid = task_tgid_nr_ns(current, ns);
+ rcu_read_lock();
+ ac.ac_ppid = task_tgid_nr_ns(rcu_dereference(current->real_parent),
+ ns);
+ rcu_read_unlock();
+ }
+#endif
+ /*
+ * Get freeze protection. If the fs is frozen, just skip the write
+ * as we could deadlock the system otherwise.
+ */
+ if (file_start_write_trylock(file)) {
+ /* it's been opened O_APPEND, so position is irrelevant */
+ loff_t pos = 0;
+ __kernel_write(file, &ac, sizeof(acct_t), &pos);
+ file_end_write(file);
+ }
+out:
+ current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim;
+ revert_creds(orig_cred);
+}
+
+/**
+ * acct_collect - collect accounting information into pacct_struct
+ * @exitcode: task exit code
+ * @group_dead: not 0, if this thread is the last one in the process.
+ */
+void acct_collect(long exitcode, int group_dead)
+{
+ struct pacct_struct *pacct = ¤t->signal->pacct;
+ u64 utime, stime;
+ unsigned long vsize = 0;
+
+ if (group_dead && current->mm) {
+ struct vm_area_struct *vma;
+
+ down_read(¤t->mm->mmap_sem);
+ vma = current->mm->mmap;
+ while (vma) {
+ vsize += vma->vm_end - vma->vm_start;
+ vma = vma->vm_next;
+ }
+ up_read(¤t->mm->mmap_sem);
+ }
+
+ spin_lock_irq(¤t->sighand->siglock);
+ if (group_dead)
+ pacct->ac_mem = vsize / 1024;
+ if (thread_group_leader(current)) {
+ pacct->ac_exitcode = exitcode;
+ if (current->flags & PF_FORKNOEXEC)
+ pacct->ac_flag |= AFORK;
+ }
+ if (current->flags & PF_SUPERPRIV)
+ pacct->ac_flag |= ASU;
+ if (current->flags & PF_DUMPCORE)
+ pacct->ac_flag |= ACORE;
+ if (current->flags & PF_SIGNALED)
+ pacct->ac_flag |= AXSIG;
+
+ task_cputime(current, &utime, &stime);
+ pacct->ac_utime += utime;
+ pacct->ac_stime += stime;
+ pacct->ac_minflt += current->min_flt;
+ pacct->ac_majflt += current->maj_flt;
+ spin_unlock_irq(¤t->sighand->siglock);
+}
+
+static void slow_acct_process(struct pid_namespace *ns)
+{
+ for ( ; ns; ns = ns->parent) {
+ struct bsd_acct_struct *acct = acct_get(ns);
+ if (acct) {
+ do_acct_process(acct);
+ mutex_unlock(&acct->lock);
+ acct_put(acct);
+ }
+ }
+}
+
+/**
+ * acct_process
+ *
+ * handles process accounting for an exiting task
+ */
+void acct_process(void)
+{
+ struct pid_namespace *ns;
+
+ /*
+ * This loop is safe lockless, since current is still
+ * alive and holds its namespace, which in turn holds
+ * its parent.
+ */
+ for (ns = task_active_pid_ns(current); ns != NULL; ns = ns->parent) {
+ if (ns->bacct)
+ break;
+ }
+ if (unlikely(ns))
+ slow_acct_process(ns);
+}