@@ -5,6 +5,7 @@ config FS_ENCRYPTION
select CRYPTO_AES
select CRYPTO_CBC
select CRYPTO_ECB
+ select CRYPTO_ESSIV
select CRYPTO_XTS
select CRYPTO_CTS
select CRYPTO_SHA256
@@ -136,9 +136,6 @@ void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
if (ci->ci_flags & FS_POLICY_FLAG_DIRECT_KEY)
memcpy(iv->nonce, ci->ci_nonce, FS_KEY_DERIVATION_NONCE_SIZE);
-
- if (ci->ci_essiv_tfm != NULL)
- crypto_cipher_encrypt_one(ci->ci_essiv_tfm, iv->raw, iv->raw);
}
int fscrypt_do_page_crypto(const struct inode *inode, fscrypt_direction_t rw,
@@ -492,8 +489,6 @@ static void __exit fscrypt_exit(void)
destroy_workqueue(fscrypt_read_workqueue);
kmem_cache_destroy(fscrypt_ctx_cachep);
kmem_cache_destroy(fscrypt_info_cachep);
-
- fscrypt_essiv_cleanup();
}
module_exit(fscrypt_exit);
@@ -61,12 +61,6 @@ struct fscrypt_info {
/* The actual crypto transform used for encryption and decryption */
struct crypto_skcipher *ci_ctfm;
- /*
- * Cipher for ESSIV IV generation. Only set for CBC contents
- * encryption, otherwise is NULL.
- */
- struct crypto_cipher *ci_essiv_tfm;
-
/*
* Encryption mode used for this inode. It corresponds to either
* ci_data_mode or ci_filename_mode, depending on the inode type.
@@ -166,9 +160,6 @@ struct fscrypt_mode {
int keysize;
int ivsize;
bool logged_impl_name;
- bool needs_essiv;
};
-extern void __exit fscrypt_essiv_cleanup(void);
-
#endif /* _FSCRYPT_PRIVATE_H */
@@ -19,8 +19,6 @@
#include <crypto/skcipher.h>
#include "fscrypt_private.h"
-static struct crypto_shash *essiv_hash_tfm;
-
/* Table of keys referenced by FS_POLICY_FLAG_DIRECT_KEY policies */
static DEFINE_HASHTABLE(fscrypt_master_keys, 6); /* 6 bits = 64 buckets */
static DEFINE_SPINLOCK(fscrypt_master_keys_lock);
@@ -144,10 +142,9 @@ static struct fscrypt_mode available_modes[] = {
},
[FS_ENCRYPTION_MODE_AES_128_CBC] = {
.friendly_name = "AES-128-CBC",
- .cipher_str = "cbc(aes)",
+ .cipher_str = "essiv(cbc(aes),aes,sha256)",
.keysize = 16,
- .ivsize = 16,
- .needs_essiv = true,
+ .ivsize = 8,
},
[FS_ENCRYPTION_MODE_AES_128_CTS] = {
.friendly_name = "AES-128-CTS-CBC",
@@ -377,72 +374,6 @@ fscrypt_get_master_key(const struct fscrypt_info *ci, struct fscrypt_mode *mode,
return ERR_PTR(err);
}
-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;
-
- 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);
-}
-
/*
* Given the encryption mode and key (normally the derived key, but for
* FS_POLICY_FLAG_DIRECT_KEY mode it's the master key), set up the inode's
@@ -454,7 +385,6 @@ static int setup_crypto_transform(struct fscrypt_info *ci,
{
struct fscrypt_master_key *mk;
struct crypto_skcipher *ctfm;
- int err;
if (ci->ci_flags & FS_POLICY_FLAG_DIRECT_KEY) {
mk = fscrypt_get_master_key(ci, mode, raw_key, inode);
@@ -470,19 +400,6 @@ static int setup_crypto_transform(struct fscrypt_info *ci,
ci->ci_master_key = mk;
ci->ci_ctfm = ctfm;
- if (mode->needs_essiv) {
- /* ESSIV implies 16-byte IVs which implies !DIRECT_KEY */
- WARN_ON(mode->ivsize != AES_BLOCK_SIZE);
- WARN_ON(ci->ci_flags & FS_POLICY_FLAG_DIRECT_KEY);
-
- err = init_essiv_generator(ci, raw_key, mode->keysize);
- if (err) {
- fscrypt_warn(inode->i_sb,
- "error initializing ESSIV generator for inode %lu: %d",
- inode->i_ino, err);
- return err;
- }
- }
return 0;
}
@@ -495,7 +412,6 @@ static void put_crypt_info(struct fscrypt_info *ci)
put_master_key(ci->ci_master_key);
} else {
crypto_free_skcipher(ci->ci_ctfm);
- crypto_free_cipher(ci->ci_essiv_tfm);
}
kmem_cache_free(fscrypt_info_cachep, ci);
}
Instead of open coding the calculations for ESSIV handling, use a ESSIV skcipher which does all of this under the hood. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- fs/crypto/Kconfig | 1 + fs/crypto/crypto.c | 5 -- fs/crypto/fscrypt_private.h | 9 -- fs/crypto/keyinfo.c | 88 +------------------- 4 files changed, 3 insertions(+), 100 deletions(-)