diff options
Diffstat (limited to 'fs/crypto/keysetup.c')
| -rw-r--r-- | fs/crypto/keysetup.c | 102 |
1 files changed, 63 insertions, 39 deletions
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c index f577bb6613f9..65cb09fa6ead 100644 --- a/fs/crypto/keysetup.c +++ b/fs/crypto/keysetup.c @@ -13,7 +13,7 @@ #include "fscrypt_private.h" -static struct fscrypt_mode available_modes[] = { +struct fscrypt_mode fscrypt_modes[] = { [FSCRYPT_MODE_AES_256_XTS] = { .friendly_name = "AES-256-XTS", .cipher_str = "xts(aes)", @@ -51,10 +51,10 @@ select_encryption_mode(const union fscrypt_policy *policy, const struct inode *inode) { if (S_ISREG(inode->i_mode)) - return &available_modes[fscrypt_policy_contents_mode(policy)]; + return &fscrypt_modes[fscrypt_policy_contents_mode(policy)]; if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) - return &available_modes[fscrypt_policy_fnames_mode(policy)]; + return &fscrypt_modes[fscrypt_policy_fnames_mode(policy)]; 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)); @@ -89,8 +89,11 @@ struct crypto_skcipher *fscrypt_allocate_skcipher(struct fscrypt_mode *mode, * first time a mode is used. */ pr_info("fscrypt: %s using implementation \"%s\"\n", - mode->friendly_name, - crypto_skcipher_alg(tfm)->base.cra_driver_name); + mode->friendly_name, crypto_skcipher_driver_name(tfm)); + } + if (WARN_ON(crypto_skcipher_ivsize(tfm) != mode->ivsize)) { + err = -EINVAL; + goto err_free_tfm; } crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS); err = crypto_skcipher_setkey(tfm, raw_key, mode->keysize); @@ -104,12 +107,12 @@ err_free_tfm: return ERR_PTR(err); } -/* Given the per-file key, set up the file's crypto transform object */ -int fscrypt_set_derived_key(struct fscrypt_info *ci, const u8 *derived_key) +/* Given a per-file encryption key, set up the file's crypto transform object */ +int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key) { struct crypto_skcipher *tfm; - tfm = fscrypt_allocate_skcipher(ci->ci_mode, derived_key, ci->ci_inode); + tfm = fscrypt_allocate_skcipher(ci->ci_mode, raw_key, ci->ci_inode); if (IS_ERR(tfm)) return PTR_ERR(tfm); @@ -118,15 +121,15 @@ int fscrypt_set_derived_key(struct fscrypt_info *ci, const u8 *derived_key) return 0; } -static int setup_per_mode_key(struct fscrypt_info *ci, - struct fscrypt_master_key *mk, - struct crypto_skcipher **tfms, - u8 hkdf_context, bool include_fs_uuid) +static int setup_per_mode_enc_key(struct fscrypt_info *ci, + struct fscrypt_master_key *mk, + struct crypto_skcipher **tfms, + u8 hkdf_context, bool include_fs_uuid) { const struct inode *inode = ci->ci_inode; const struct super_block *sb = inode->i_sb; struct fscrypt_mode *mode = ci->ci_mode; - u8 mode_num = mode - available_modes; + const u8 mode_num = mode - fscrypt_modes; struct crypto_skcipher *tfm, *prev_tfm; u8 mode_key[FSCRYPT_MAX_KEY_SIZE]; u8 hkdf_info[sizeof(mode_num) + sizeof(sb->s_uuid)]; @@ -171,29 +174,37 @@ done: return 0; } +int fscrypt_derive_dirhash_key(struct fscrypt_info *ci, + const struct fscrypt_master_key *mk) +{ + int err; + + err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, HKDF_CONTEXT_DIRHASH_KEY, + ci->ci_nonce, FS_KEY_DERIVATION_NONCE_SIZE, + (u8 *)&ci->ci_dirhash_key, + sizeof(ci->ci_dirhash_key)); + if (err) + return err; + ci->ci_dirhash_key_initialized = true; + return 0; +} + static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci, struct fscrypt_master_key *mk) { - u8 derived_key[FSCRYPT_MAX_KEY_SIZE]; int err; if (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) { /* - * DIRECT_KEY: instead of deriving per-file keys, the per-file - * nonce will be included in all the IVs. But unlike v1 - * policies, for v2 policies in this case we don't encrypt with - * the master key directly but rather derive a per-mode key. - * This ensures that the master key is consistently used only - * for HKDF, avoiding key reuse issues. + * DIRECT_KEY: instead of deriving per-file encryption keys, the + * per-file nonce will be included in all the IVs. But unlike + * v1 policies, for v2 policies in this case we don't encrypt + * with the master key directly but rather derive a per-mode + * encryption key. This ensures that the master key is + * consistently used only for HKDF, avoiding key reuse issues. */ - if (!fscrypt_mode_supports_direct_key(ci->ci_mode)) { - fscrypt_warn(ci->ci_inode, - "Direct key flag not allowed with %s", - ci->ci_mode->friendly_name); - return -EINVAL; - } - return setup_per_mode_key(ci, mk, mk->mk_direct_tfms, - HKDF_CONTEXT_DIRECT_KEY, false); + err = setup_per_mode_enc_key(ci, mk, mk->mk_direct_tfms, + HKDF_CONTEXT_DIRECT_KEY, false); } else if (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) { /* @@ -202,21 +213,34 @@ static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci, * the IVs. This format is optimized for use with inline * encryption hardware compliant with the UFS or eMMC standards. */ - return setup_per_mode_key(ci, mk, mk->mk_iv_ino_lblk_64_tfms, - HKDF_CONTEXT_IV_INO_LBLK_64_KEY, - true); + err = setup_per_mode_enc_key(ci, mk, mk->mk_iv_ino_lblk_64_tfms, + HKDF_CONTEXT_IV_INO_LBLK_64_KEY, + true); + } else { + u8 derived_key[FSCRYPT_MAX_KEY_SIZE]; + + err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, + HKDF_CONTEXT_PER_FILE_ENC_KEY, + ci->ci_nonce, + FS_KEY_DERIVATION_NONCE_SIZE, + derived_key, ci->ci_mode->keysize); + if (err) + return err; + + err = fscrypt_set_per_file_enc_key(ci, derived_key); + memzero_explicit(derived_key, ci->ci_mode->keysize); } - - err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, - HKDF_CONTEXT_PER_FILE_KEY, - ci->ci_nonce, FS_KEY_DERIVATION_NONCE_SIZE, - derived_key, ci->ci_mode->keysize); if (err) return err; - err = fscrypt_set_derived_key(ci, derived_key); - memzero_explicit(derived_key, ci->ci_mode->keysize); - return err; + /* Derive a secret dirhash key for directories that need it. */ + if (S_ISDIR(ci->ci_inode->i_mode) && IS_CASEFOLDED(ci->ci_inode)) { + err = fscrypt_derive_dirhash_key(ci, mk); + if (err) + return err; + } + + return 0; } /* |