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-rw-r--r--fs/crypto/keyinfo.c122
1 files changed, 74 insertions, 48 deletions
diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c
index f63bfd6dffd6..f248ee9974fa 100644
--- a/fs/crypto/keyinfo.c
+++ b/fs/crypto/keyinfo.c
@@ -27,7 +27,7 @@ static struct crypto_shash *essiv_hash_tfm;
*
* Return: Zero on success; non-zero otherwise.
*/
-static int derive_key_aes(u8 deriving_key[FS_KEY_DERIVATION_NONCE_SIZE],
+static int derive_key_aes(const u8 deriving_key[FS_KEY_DERIVATION_NONCE_SIZE],
const struct fscrypt_key *source_key,
u8 derived_raw_key[FS_MAX_KEY_SIZE])
{
@@ -67,52 +67,88 @@ out:
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)
+/*
+ * Search the current task's subscribed keyrings for a "logon" key with
+ * description prefix:descriptor, and if found acquire a read lock on it and
+ * return a pointer to its validated payload in *payload_ret.
+ */
+static struct key *
+find_and_lock_process_key(const char *prefix,
+ const u8 descriptor[FS_KEY_DESCRIPTOR_SIZE],
+ unsigned int min_keysize,
+ const struct fscrypt_key **payload_ret)
{
char *description;
- struct key *keyring_key;
- struct fscrypt_key *master_key;
+ struct key *key;
const struct user_key_payload *ukp;
- int res;
+ const struct fscrypt_key *payload;
description = kasprintf(GFP_NOFS, "%s%*phN", prefix,
- FS_KEY_DESCRIPTOR_SIZE,
- ctx->master_key_descriptor);
+ FS_KEY_DESCRIPTOR_SIZE, descriptor);
if (!description)
- return -ENOMEM;
+ return ERR_PTR(-ENOMEM);
- keyring_key = request_key(&key_type_logon, description, NULL);
+ 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);
-
- ukp = user_key_payload_locked(keyring_key);
- if (!ukp) {
- /* key was revoked before we acquired its semaphore */
- res = -EKEYREVOKED;
- goto out;
+ if (IS_ERR(key))
+ return key;
+
+ down_read(&key->sem);
+ ukp = user_key_payload_locked(key);
+
+ if (!ukp) /* was the key revoked before we acquired its semaphore? */
+ goto invalid;
+
+ payload = (const struct fscrypt_key *)ukp->data;
+
+ if (ukp->datalen != sizeof(struct fscrypt_key) ||
+ payload->size < 1 || payload->size > FS_MAX_KEY_SIZE) {
+ fscrypt_warn(NULL,
+ "key with description '%s' has invalid payload",
+ key->description);
+ goto invalid;
}
- if (ukp->datalen != sizeof(struct fscrypt_key)) {
- res = -EINVAL;
- goto out;
+
+ if (payload->size < min_keysize ||
+ payload->size % AES_BLOCK_SIZE != 0) {
+ fscrypt_warn(NULL,
+ "key with description '%s' is too short or is misaligned (got %u bytes, need %u+ bytes)",
+ key->description, payload->size, min_keysize);
+ goto invalid;
}
- master_key = (struct fscrypt_key *)ukp->data;
- if (master_key->size < min_keysize || master_key->size > FS_MAX_KEY_SIZE
- || master_key->size % AES_BLOCK_SIZE != 0) {
- fscrypt_warn(NULL, "key size incorrect: %u",
- master_key->size);
- res = -ENOKEY;
- goto out;
+ *payload_ret = payload;
+ return key;
+
+invalid:
+ up_read(&key->sem);
+ key_put(key);
+ return ERR_PTR(-ENOKEY);
+}
+
+/* Find the master key, then derive the inode's actual encryption key */
+static int find_and_derive_key(const struct inode *inode,
+ const struct fscrypt_context *ctx,
+ u8 *derived_key, unsigned int derived_keysize)
+{
+ struct key *key;
+ const struct fscrypt_key *payload;
+ int err;
+
+ key = find_and_lock_process_key(FS_KEY_DESC_PREFIX,
+ ctx->master_key_descriptor,
+ derived_keysize, &payload);
+ if (key == ERR_PTR(-ENOKEY) && inode->i_sb->s_cop->key_prefix) {
+ key = find_and_lock_process_key(inode->i_sb->s_cop->key_prefix,
+ ctx->master_key_descriptor,
+ derived_keysize, &payload);
}
- res = derive_key_aes(ctx->nonce, master_key, raw_key);
-out:
- up_read(&keyring_key->sem);
- key_put(keyring_key);
- return res;
+ if (IS_ERR(key))
+ return PTR_ERR(key);
+ err = derive_key_aes(ctx->nonce, payload, derived_key);
+ up_read(&key->sem);
+ key_put(key);
+ return err;
}
static const struct {
@@ -293,20 +329,10 @@ int fscrypt_get_encryption_info(struct inode *inode)
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) {
+ res = find_and_derive_key(inode, &ctx, raw_key, keysize);
+ if (res)
goto out;
- }
+
ctfm = crypto_alloc_skcipher(cipher_str, 0, 0);
if (IS_ERR(ctfm)) {
res = PTR_ERR(ctfm);