v4.19.13 snapshot.
diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c
new file mode 100644
index 0000000..7874c9b
--- /dev/null
+++ b/fs/crypto/keyinfo.c
@@ -0,0 +1,399 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * key management facility for FS encryption support.
+ *
+ * Copyright (C) 2015, Google, Inc.
+ *
+ * This contains encryption key functions.
+ *
+ * Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.
+ */
+
+#include <keys/user-type.h>
+#include <linux/scatterlist.h>
+#include <linux/ratelimit.h>
+#include <crypto/aes.h>
+#include <crypto/sha.h>
+#include <crypto/skcipher.h>
+#include "fscrypt_private.h"
+
+static struct crypto_shash *essiv_hash_tfm;
+
+/*
+ * Key derivation function. This generates the derived key by encrypting the
+ * master key with AES-128-ECB using the inode's nonce as the AES key.
+ *
+ * The master key must be at least as long as the derived key. If the master
+ * key is longer, then only the first 'derived_keysize' bytes are used.
+ */
+static int derive_key_aes(const u8 *master_key,
+ const struct fscrypt_context *ctx,
+ u8 *derived_key, unsigned int derived_keysize)
+{
+ int res = 0;
+ struct skcipher_request *req = NULL;
+ DECLARE_CRYPTO_WAIT(wait);
+ struct scatterlist src_sg, dst_sg;
+ struct crypto_skcipher *tfm = crypto_alloc_skcipher("ecb(aes)", 0, 0);
+
+ if (IS_ERR(tfm)) {
+ res = PTR_ERR(tfm);
+ tfm = NULL;
+ goto out;
+ }
+ crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_WEAK_KEY);
+ req = skcipher_request_alloc(tfm, GFP_NOFS);
+ if (!req) {
+ res = -ENOMEM;
+ goto out;
+ }
+ skcipher_request_set_callback(req,
+ CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
+ crypto_req_done, &wait);
+ res = crypto_skcipher_setkey(tfm, ctx->nonce, sizeof(ctx->nonce));
+ if (res < 0)
+ goto out;
+
+ sg_init_one(&src_sg, master_key, derived_keysize);
+ sg_init_one(&dst_sg, derived_key, derived_keysize);
+ skcipher_request_set_crypt(req, &src_sg, &dst_sg, derived_keysize,
+ NULL);
+ res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
+out:
+ skcipher_request_free(req);
+ crypto_free_skcipher(tfm);
+ return res;
+}
+
+/*
+ * Search the current task's subscribed keyrings for a "logon" key with
+ * description prefix:descriptor, and if found acquire a read lock on it and
+ * return a pointer to its validated payload in *payload_ret.
+ */
+static struct key *
+find_and_lock_process_key(const char *prefix,
+ const u8 descriptor[FS_KEY_DESCRIPTOR_SIZE],
+ unsigned int min_keysize,
+ const struct fscrypt_key **payload_ret)
+{
+ char *description;
+ struct key *key;
+ const struct user_key_payload *ukp;
+ const struct fscrypt_key *payload;
+
+ description = kasprintf(GFP_NOFS, "%s%*phN", prefix,
+ FS_KEY_DESCRIPTOR_SIZE, descriptor);
+ if (!description)
+ return ERR_PTR(-ENOMEM);
+
+ key = request_key(&key_type_logon, description, NULL);
+ kfree(description);
+ if (IS_ERR(key))
+ return key;
+
+ down_read(&key->sem);
+ ukp = user_key_payload_locked(key);
+
+ if (!ukp) /* was the key revoked before we acquired its semaphore? */
+ goto invalid;
+
+ payload = (const struct fscrypt_key *)ukp->data;
+
+ if (ukp->datalen != sizeof(struct fscrypt_key) ||
+ payload->size < 1 || payload->size > FS_MAX_KEY_SIZE) {
+ fscrypt_warn(NULL,
+ "key with description '%s' has invalid payload",
+ key->description);
+ goto invalid;
+ }
+
+ if (payload->size < min_keysize) {
+ fscrypt_warn(NULL,
+ "key with description '%s' is too short (got %u bytes, need %u+ bytes)",
+ key->description, payload->size, min_keysize);
+ goto invalid;
+ }
+
+ *payload_ret = payload;
+ return key;
+
+invalid:
+ up_read(&key->sem);
+ key_put(key);
+ return ERR_PTR(-ENOKEY);
+}
+
+/* Find the master key, then derive the inode's actual encryption key */
+static int find_and_derive_key(const struct inode *inode,
+ const struct fscrypt_context *ctx,
+ u8 *derived_key, unsigned int derived_keysize)
+{
+ struct key *key;
+ const struct fscrypt_key *payload;
+ int err;
+
+ key = find_and_lock_process_key(FS_KEY_DESC_PREFIX,
+ ctx->master_key_descriptor,
+ derived_keysize, &payload);
+ if (key == ERR_PTR(-ENOKEY) && inode->i_sb->s_cop->key_prefix) {
+ key = find_and_lock_process_key(inode->i_sb->s_cop->key_prefix,
+ ctx->master_key_descriptor,
+ derived_keysize, &payload);
+ }
+ if (IS_ERR(key))
+ return PTR_ERR(key);
+ err = derive_key_aes(payload->raw, ctx, derived_key, derived_keysize);
+ up_read(&key->sem);
+ key_put(key);
+ return err;
+}
+
+static struct fscrypt_mode {
+ const char *friendly_name;
+ const char *cipher_str;
+ int keysize;
+ bool logged_impl_name;
+} available_modes[] = {
+ [FS_ENCRYPTION_MODE_AES_256_XTS] = {
+ .friendly_name = "AES-256-XTS",
+ .cipher_str = "xts(aes)",
+ .keysize = 64,
+ },
+ [FS_ENCRYPTION_MODE_AES_256_CTS] = {
+ .friendly_name = "AES-256-CTS-CBC",
+ .cipher_str = "cts(cbc(aes))",
+ .keysize = 32,
+ },
+ [FS_ENCRYPTION_MODE_AES_128_CBC] = {
+ .friendly_name = "AES-128-CBC",
+ .cipher_str = "cbc(aes)",
+ .keysize = 16,
+ },
+ [FS_ENCRYPTION_MODE_AES_128_CTS] = {
+ .friendly_name = "AES-128-CTS-CBC",
+ .cipher_str = "cts(cbc(aes))",
+ .keysize = 16,
+ },
+};
+
+static struct fscrypt_mode *
+select_encryption_mode(const struct fscrypt_info *ci, const struct inode *inode)
+{
+ if (!fscrypt_valid_enc_modes(ci->ci_data_mode, ci->ci_filename_mode)) {
+ fscrypt_warn(inode->i_sb,
+ "inode %lu uses unsupported encryption modes (contents mode %d, filenames mode %d)",
+ inode->i_ino, ci->ci_data_mode,
+ ci->ci_filename_mode);
+ return ERR_PTR(-EINVAL);
+ }
+
+ if (S_ISREG(inode->i_mode))
+ return &available_modes[ci->ci_data_mode];
+
+ if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
+ return &available_modes[ci->ci_filename_mode];
+
+ WARN_ONCE(1, "fscrypt: filesystem tried to load encryption info for inode %lu, which is not encryptable (file type %d)\n",
+ inode->i_ino, (inode->i_mode & S_IFMT));
+ return ERR_PTR(-EINVAL);
+}
+
+static void put_crypt_info(struct fscrypt_info *ci)
+{
+ if (!ci)
+ return;
+
+ crypto_free_skcipher(ci->ci_ctfm);
+ crypto_free_cipher(ci->ci_essiv_tfm);
+ kmem_cache_free(fscrypt_info_cachep, ci);
+}
+
+static int derive_essiv_salt(const u8 *key, int keysize, u8 *salt)
+{
+ struct crypto_shash *tfm = READ_ONCE(essiv_hash_tfm);
+
+ /* init hash transform on demand */
+ if (unlikely(!tfm)) {
+ struct crypto_shash *prev_tfm;
+
+ tfm = crypto_alloc_shash("sha256", 0, 0);
+ if (IS_ERR(tfm)) {
+ fscrypt_warn(NULL,
+ "error allocating SHA-256 transform: %ld",
+ PTR_ERR(tfm));
+ return PTR_ERR(tfm);
+ }
+ prev_tfm = cmpxchg(&essiv_hash_tfm, NULL, tfm);
+ if (prev_tfm) {
+ crypto_free_shash(tfm);
+ tfm = prev_tfm;
+ }
+ }
+
+ {
+ SHASH_DESC_ON_STACK(desc, tfm);
+ desc->tfm = tfm;
+ desc->flags = 0;
+
+ return crypto_shash_digest(desc, key, keysize, salt);
+ }
+}
+
+static int init_essiv_generator(struct fscrypt_info *ci, const u8 *raw_key,
+ int keysize)
+{
+ int err;
+ struct crypto_cipher *essiv_tfm;
+ u8 salt[SHA256_DIGEST_SIZE];
+
+ essiv_tfm = crypto_alloc_cipher("aes", 0, 0);
+ if (IS_ERR(essiv_tfm))
+ return PTR_ERR(essiv_tfm);
+
+ ci->ci_essiv_tfm = essiv_tfm;
+
+ err = derive_essiv_salt(raw_key, keysize, salt);
+ if (err)
+ goto out;
+
+ /*
+ * Using SHA256 to derive the salt/key will result in AES-256 being
+ * used for IV generation. File contents encryption will still use the
+ * configured keysize (AES-128) nevertheless.
+ */
+ err = crypto_cipher_setkey(essiv_tfm, salt, sizeof(salt));
+ if (err)
+ goto out;
+
+out:
+ memzero_explicit(salt, sizeof(salt));
+ return err;
+}
+
+void __exit fscrypt_essiv_cleanup(void)
+{
+ crypto_free_shash(essiv_hash_tfm);
+}
+
+int fscrypt_get_encryption_info(struct inode *inode)
+{
+ struct fscrypt_info *crypt_info;
+ struct fscrypt_context ctx;
+ struct crypto_skcipher *ctfm;
+ struct fscrypt_mode *mode;
+ u8 *raw_key = NULL;
+ int res;
+
+ if (inode->i_crypt_info)
+ return 0;
+
+ res = fscrypt_initialize(inode->i_sb->s_cop->flags);
+ if (res)
+ return res;
+
+ res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
+ if (res < 0) {
+ if (!fscrypt_dummy_context_enabled(inode) ||
+ IS_ENCRYPTED(inode))
+ return res;
+ /* Fake up a context for an unencrypted directory */
+ memset(&ctx, 0, sizeof(ctx));
+ ctx.format = FS_ENCRYPTION_CONTEXT_FORMAT_V1;
+ ctx.contents_encryption_mode = FS_ENCRYPTION_MODE_AES_256_XTS;
+ ctx.filenames_encryption_mode = FS_ENCRYPTION_MODE_AES_256_CTS;
+ memset(ctx.master_key_descriptor, 0x42, FS_KEY_DESCRIPTOR_SIZE);
+ } else if (res != sizeof(ctx)) {
+ return -EINVAL;
+ }
+
+ if (ctx.format != FS_ENCRYPTION_CONTEXT_FORMAT_V1)
+ return -EINVAL;
+
+ if (ctx.flags & ~FS_POLICY_FLAGS_VALID)
+ return -EINVAL;
+
+ crypt_info = kmem_cache_alloc(fscrypt_info_cachep, GFP_NOFS);
+ if (!crypt_info)
+ return -ENOMEM;
+
+ crypt_info->ci_flags = ctx.flags;
+ crypt_info->ci_data_mode = ctx.contents_encryption_mode;
+ crypt_info->ci_filename_mode = ctx.filenames_encryption_mode;
+ crypt_info->ci_ctfm = NULL;
+ crypt_info->ci_essiv_tfm = NULL;
+ memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor,
+ sizeof(crypt_info->ci_master_key));
+
+ mode = select_encryption_mode(crypt_info, inode);
+ if (IS_ERR(mode)) {
+ res = PTR_ERR(mode);
+ goto out;
+ }
+
+ /*
+ * This cannot be a stack buffer because it is passed to the scatterlist
+ * crypto API as part of key derivation.
+ */
+ res = -ENOMEM;
+ raw_key = kmalloc(mode->keysize, GFP_NOFS);
+ if (!raw_key)
+ goto out;
+
+ res = find_and_derive_key(inode, &ctx, raw_key, mode->keysize);
+ if (res)
+ goto out;
+
+ ctfm = crypto_alloc_skcipher(mode->cipher_str, 0, 0);
+ if (IS_ERR(ctfm)) {
+ res = PTR_ERR(ctfm);
+ fscrypt_warn(inode->i_sb,
+ "error allocating '%s' transform for inode %lu: %d",
+ mode->cipher_str, inode->i_ino, res);
+ goto out;
+ }
+ if (unlikely(!mode->logged_impl_name)) {
+ /*
+ * fscrypt performance can vary greatly depending on which
+ * crypto algorithm implementation is used. Help people debug
+ * performance problems by logging the ->cra_driver_name the
+ * first time a mode is used. Note that multiple threads can
+ * race here, but it doesn't really matter.
+ */
+ mode->logged_impl_name = true;
+ pr_info("fscrypt: %s using implementation \"%s\"\n",
+ mode->friendly_name,
+ crypto_skcipher_alg(ctfm)->base.cra_driver_name);
+ }
+ crypt_info->ci_ctfm = ctfm;
+ crypto_skcipher_set_flags(ctfm, CRYPTO_TFM_REQ_WEAK_KEY);
+ res = crypto_skcipher_setkey(ctfm, raw_key, mode->keysize);
+ if (res)
+ goto out;
+
+ if (S_ISREG(inode->i_mode) &&
+ crypt_info->ci_data_mode == FS_ENCRYPTION_MODE_AES_128_CBC) {
+ res = init_essiv_generator(crypt_info, raw_key, mode->keysize);
+ if (res) {
+ fscrypt_warn(inode->i_sb,
+ "error initializing ESSIV generator for inode %lu: %d",
+ inode->i_ino, res);
+ goto out;
+ }
+ }
+ if (cmpxchg(&inode->i_crypt_info, NULL, crypt_info) == NULL)
+ crypt_info = NULL;
+out:
+ if (res == -ENOKEY)
+ res = 0;
+ put_crypt_info(crypt_info);
+ kzfree(raw_key);
+ return res;
+}
+EXPORT_SYMBOL(fscrypt_get_encryption_info);
+
+void fscrypt_put_encryption_info(struct inode *inode)
+{
+ put_crypt_info(inode->i_crypt_info);
+ inode->i_crypt_info = NULL;
+}
+EXPORT_SYMBOL(fscrypt_put_encryption_info);