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[2.15.62.10]) by smtp.gmail.com with ESMTPSA id h21sm2273831wmb.47.2019.06.18.14.28.05 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 18 Jun 2019 14:28:06 -0700 (PDT) From: Ard Biesheuvel To: linux-crypto@vger.kernel.org Cc: Ard Biesheuvel , Herbert Xu , Eric Biggers , dm-devel@redhat.com, linux-fscrypt@vger.kernel.org, Gilad Ben-Yossef , Milan Broz Subject: [PATCH v2 2/4] fs: crypto: invoke crypto API for ESSIV handling Date: Tue, 18 Jun 2019 23:27:47 +0200 Message-Id: <20190618212749.8995-3-ard.biesheuvel@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190618212749.8995-1-ard.biesheuvel@linaro.org> References: <20190618212749.8995-1-ard.biesheuvel@linaro.org> Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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 --- 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(-) diff --git a/fs/crypto/Kconfig b/fs/crypto/Kconfig index 24ed99e2eca0..b0292da8613c 100644 --- a/fs/crypto/Kconfig +++ b/fs/crypto/Kconfig @@ -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 diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c index 335a362ee446..c53ce262a06c 100644 --- a/fs/crypto/crypto.c +++ b/fs/crypto/crypto.c @@ -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); diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h index 7da276159593..59d0cba9cfb9 100644 --- a/fs/crypto/fscrypt_private.h +++ b/fs/crypto/fscrypt_private.h @@ -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 */ diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c index dcd91a3fbe49..82c7eb86ca00 100644 --- a/fs/crypto/keyinfo.c +++ b/fs/crypto/keyinfo.c @@ -19,8 +19,6 @@ #include #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); }