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authorLinus Torvalds <torvalds@linux-foundation.org>2021-06-28 16:20:48 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-06-28 16:20:48 -0700
commita58e203530ebdf6e5413bebc7f976d756188a4b5 (patch)
tree018d34c1f747bbbc064b303b8f678c79e748249d /fs
parenta60c538ed2ff9d084544a894219eed9c5ab980e5 (diff)
parent2fc2b430f559fdf32d5d1dd5ceaa40e12fb77bdf (diff)
Merge tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt
Pull fscrypt updates from Eric Biggers: "A couple bug fixes for fs/crypto/: - Fix handling of major dirhash values that happen to be 0. - Fix cases where keys were derived differently on big endian systems than on little endian systems (affecting some newer features only)" * tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt: fscrypt: fix derivation of SipHash keys on big endian CPUs fscrypt: don't ignore minor_hash when hash is 0
Diffstat (limited to 'fs')
-rw-r--r--fs/crypto/fname.c10
-rw-r--r--fs/crypto/keysetup.c40
2 files changed, 35 insertions, 15 deletions
diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
index 6ca7d16593ff..d00455440d08 100644
--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -344,13 +344,9 @@ int fscrypt_fname_disk_to_usr(const struct inode *inode,
offsetof(struct fscrypt_nokey_name, sha256));
BUILD_BUG_ON(BASE64_CHARS(FSCRYPT_NOKEY_NAME_MAX) > NAME_MAX);
- if (hash) {
- nokey_name.dirhash[0] = hash;
- nokey_name.dirhash[1] = minor_hash;
- } else {
- nokey_name.dirhash[0] = 0;
- nokey_name.dirhash[1] = 0;
- }
+ nokey_name.dirhash[0] = hash;
+ nokey_name.dirhash[1] = minor_hash;
+
if (iname->len <= sizeof(nokey_name.bytes)) {
memcpy(nokey_name.bytes, iname->name, iname->len);
size = offsetof(struct fscrypt_nokey_name, bytes[iname->len]);
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
index 261293fb7097..bca9c6658a7c 100644
--- a/fs/crypto/keysetup.c
+++ b/fs/crypto/keysetup.c
@@ -210,15 +210,40 @@ out_unlock:
return err;
}
+/*
+ * Derive a SipHash key from the given fscrypt master key and the given
+ * application-specific information string.
+ *
+ * Note that the KDF produces a byte array, but the SipHash APIs expect the key
+ * as a pair of 64-bit words. Therefore, on big endian CPUs we have to do an
+ * endianness swap in order to get the same results as on little endian CPUs.
+ */
+static int fscrypt_derive_siphash_key(const struct fscrypt_master_key *mk,
+ u8 context, const u8 *info,
+ unsigned int infolen, siphash_key_t *key)
+{
+ int err;
+
+ err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, context, info, infolen,
+ (u8 *)key, sizeof(*key));
+ if (err)
+ return err;
+
+ BUILD_BUG_ON(sizeof(*key) != 16);
+ BUILD_BUG_ON(ARRAY_SIZE(key->key) != 2);
+ le64_to_cpus(&key->key[0]);
+ le64_to_cpus(&key->key[1]);
+ 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, FSCRYPT_FILE_NONCE_SIZE,
- (u8 *)&ci->ci_dirhash_key,
- sizeof(ci->ci_dirhash_key));
+ err = fscrypt_derive_siphash_key(mk, HKDF_CONTEXT_DIRHASH_KEY,
+ ci->ci_nonce, FSCRYPT_FILE_NONCE_SIZE,
+ &ci->ci_dirhash_key);
if (err)
return err;
ci->ci_dirhash_key_initialized = true;
@@ -253,10 +278,9 @@ static int fscrypt_setup_iv_ino_lblk_32_key(struct fscrypt_info *ci,
if (mk->mk_ino_hash_key_initialized)
goto unlock;
- err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf,
- HKDF_CONTEXT_INODE_HASH_KEY, NULL, 0,
- (u8 *)&mk->mk_ino_hash_key,
- sizeof(mk->mk_ino_hash_key));
+ err = fscrypt_derive_siphash_key(mk,
+ HKDF_CONTEXT_INODE_HASH_KEY,
+ NULL, 0, &mk->mk_ino_hash_key);
if (err)
goto unlock;
/* pairs with smp_load_acquire() above */