diff options
Diffstat (limited to 'fs/crypto/keyinfo.c')
-rw-r--r-- | fs/crypto/keyinfo.c | 387 |
1 files changed, 0 insertions, 387 deletions
diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c deleted file mode 100644 index a38630214058..000000000000 --- a/fs/crypto/keyinfo.c +++ /dev/null @@ -1,387 +0,0 @@ -// 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 "fscrypt_private.h" - -static struct crypto_shash *essiv_hash_tfm; - -static void derive_crypt_complete(struct crypto_async_request *req, int rc) -{ - struct fscrypt_completion_result *ecr = req->data; - - if (rc == -EINPROGRESS) - return; - - ecr->res = rc; - complete(&ecr->completion); -} - -/** - * derive_key_aes() - Derive a key using AES-128-ECB - * @deriving_key: Encryption key used for derivation. - * @source_key: Source key to which to apply derivation. - * @derived_raw_key: Derived raw key. - * - * Return: Zero on success; non-zero otherwise. - */ -static int derive_key_aes(u8 deriving_key[FS_AES_128_ECB_KEY_SIZE], - const struct fscrypt_key *source_key, - u8 derived_raw_key[FS_MAX_KEY_SIZE]) -{ - int res = 0; - struct skcipher_request *req = NULL; - DECLARE_FS_COMPLETION_RESULT(ecr); - 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, - derive_crypt_complete, &ecr); - res = crypto_skcipher_setkey(tfm, deriving_key, - FS_AES_128_ECB_KEY_SIZE); - if (res < 0) - goto out; - - sg_init_one(&src_sg, source_key->raw, source_key->size); - sg_init_one(&dst_sg, derived_raw_key, source_key->size); - skcipher_request_set_crypt(req, &src_sg, &dst_sg, source_key->size, - NULL); - res = crypto_skcipher_encrypt(req); - if (res == -EINPROGRESS || res == -EBUSY) { - wait_for_completion(&ecr.completion); - res = ecr.res; - } -out: - skcipher_request_free(req); - crypto_free_skcipher(tfm); - return res; -} - -static int validate_user_key(struct fscrypt_info *crypt_info, - struct fscrypt_context *ctx, u8 *raw_key, - const char *prefix, int min_keysize) -{ - char *description; - struct key *keyring_key; - struct fscrypt_key *master_key; - const struct user_key_payload *ukp; - int res; - - description = kasprintf(GFP_NOFS, "%s%*phN", prefix, - FS_KEY_DESCRIPTOR_SIZE, - ctx->master_key_descriptor); - if (!description) - return -ENOMEM; - - keyring_key = request_key(&key_type_logon, description, NULL); - kfree(description); - if (IS_ERR(keyring_key)) - return PTR_ERR(keyring_key); - down_read(&keyring_key->sem); - - if (keyring_key->type != &key_type_logon) { - printk_once(KERN_WARNING - "%s: key type must be logon\n", __func__); - res = -ENOKEY; - goto out; - } - ukp = user_key_payload_locked(keyring_key); - if (!ukp) { - /* key was revoked before we acquired its semaphore */ - res = -EKEYREVOKED; - goto out; - } - if (ukp->datalen != sizeof(struct fscrypt_key)) { - res = -EINVAL; - goto out; - } - master_key = (struct fscrypt_key *)ukp->data; - BUILD_BUG_ON(FS_AES_128_ECB_KEY_SIZE != FS_KEY_DERIVATION_NONCE_SIZE); - - if (master_key->size < min_keysize || master_key->size > FS_MAX_KEY_SIZE - || master_key->size % AES_BLOCK_SIZE != 0) { - printk_once(KERN_WARNING - "%s: key size incorrect: %d\n", - __func__, master_key->size); - res = -ENOKEY; - goto out; - } - res = derive_key_aes(ctx->nonce, master_key, raw_key); -out: - up_read(&keyring_key->sem); - key_put(keyring_key); - return res; -} - -static const struct { - const char *cipher_str; - int keysize; -} available_modes[] = { - [FS_ENCRYPTION_MODE_AES_256_XTS] = { "xts(aes)", - FS_AES_256_XTS_KEY_SIZE }, - [FS_ENCRYPTION_MODE_AES_256_CTS] = { "cts(cbc(aes))", - FS_AES_256_CTS_KEY_SIZE }, - [FS_ENCRYPTION_MODE_AES_128_CBC] = { "cbc(aes)", - FS_AES_128_CBC_KEY_SIZE }, - [FS_ENCRYPTION_MODE_AES_128_CTS] = { "cts(cbc(aes))", - FS_AES_128_CTS_KEY_SIZE }, -}; - -static int determine_cipher_type(struct fscrypt_info *ci, struct inode *inode, - const char **cipher_str_ret, int *keysize_ret) -{ - u32 mode; - - if (!fscrypt_valid_enc_modes(ci->ci_data_mode, ci->ci_filename_mode)) { - pr_warn_ratelimited("fscrypt: inode %lu uses unsupported encryption modes (contents mode %d, filenames mode %d)\n", - inode->i_ino, - ci->ci_data_mode, ci->ci_filename_mode); - return -EINVAL; - } - - if (S_ISREG(inode->i_mode)) { - mode = ci->ci_data_mode; - } else if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) { - mode = ci->ci_filename_mode; - } else { - 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 -EINVAL; - } - - *cipher_str_ret = available_modes[mode].cipher_str; - *keysize_ret = available_modes[mode].keysize; - return 0; -} - -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)) { - pr_warn_ratelimited("fscrypt: error allocating SHA-256 transform: %ld\n", - 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; - const char *cipher_str; - int keysize; - 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) || - inode->i_sb->s_cop->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)); - - res = determine_cipher_type(crypt_info, inode, &cipher_str, &keysize); - if (res) - 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(FS_MAX_KEY_SIZE, GFP_NOFS); - if (!raw_key) - goto out; - - res = validate_user_key(crypt_info, &ctx, raw_key, FS_KEY_DESC_PREFIX, - keysize); - if (res && inode->i_sb->s_cop->key_prefix) { - int res2 = validate_user_key(crypt_info, &ctx, raw_key, - inode->i_sb->s_cop->key_prefix, - keysize); - if (res2) { - if (res2 == -ENOKEY) - res = -ENOKEY; - goto out; - } - } else if (res) { - goto out; - } - ctfm = crypto_alloc_skcipher(cipher_str, 0, 0); - if (!ctfm || IS_ERR(ctfm)) { - res = ctfm ? PTR_ERR(ctfm) : -ENOMEM; - pr_debug("%s: error %d (inode %lu) allocating crypto tfm\n", - __func__, res, inode->i_ino); - goto out; - } - crypt_info->ci_ctfm = ctfm; - crypto_skcipher_clear_flags(ctfm, ~0); - crypto_skcipher_set_flags(ctfm, CRYPTO_TFM_REQ_WEAK_KEY); - /* - * if the provided key is longer than keysize, we use the first - * keysize bytes of the derived key only - */ - res = crypto_skcipher_setkey(ctfm, raw_key, 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, keysize); - if (res) { - pr_debug("%s: error %d (inode %lu) allocating essiv tfm\n", - __func__, res, inode->i_ino); - 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, struct fscrypt_info *ci) -{ - struct fscrypt_info *prev; - - if (ci == NULL) - ci = ACCESS_ONCE(inode->i_crypt_info); - if (ci == NULL) - return; - - prev = cmpxchg(&inode->i_crypt_info, ci, NULL); - if (prev != ci) - return; - - put_crypt_info(ci); -} -EXPORT_SYMBOL(fscrypt_put_encryption_info); |