[PATCH AUTOSEL 4.14 021/105] fscrypt: clean up some BUG_ON()s in block encryption/decryption

Sasha Levin
2019-07-15T14:30:04Z

From: Eric Biggers <ebiggers@google.com>

[ Upstream commit eeacfdc68a104967162dfcba60f53f6f5b62a334 ]

Replace some BUG_ON()s with WARN_ON_ONCE() and returning an error code,
and move the check for len divisible by FS_CRYPTO_BLOCK_SIZE into
fscrypt_crypt_block() so that it's done for both encryption and
decryption, not just encryption.

Reviewed-by: Chandan Rajendra <chandan@linux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/crypto/crypto.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index daf2683f0655..f862ad19c714 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -157,7 +157,10 @@ int fscrypt_do_page_crypto(const struct inode *inode, fscrypt_direction_t rw,
struct crypto_skcipher *tfm = ci->ci_ctfm;
int res = 0;

- BUG_ON(len == 0);
+ if (WARN_ON_ONCE(len <= 0))
+ return -EINVAL;
+ if (WARN_ON_ONCE(len % FS_CRYPTO_BLOCK_SIZE != 0))
+ return -EINVAL;

BUILD_BUG_ON(sizeof(iv) != FS_IV_SIZE);
BUILD_BUG_ON(AES_BLOCK_SIZE != FS_IV_SIZE);
@@ -257,8 +260,6 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
struct page *ciphertext_page = page;
int err;

- BUG_ON(len % FS_CRYPTO_BLOCK_SIZE != 0);
-
if (inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES) {
/* with inplace-encryption we just encrypt the page */
err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk_num, page,
@@ -270,7 +271,8 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
return ciphertext_page;
}

- BUG_ON(!PageLocked(page));
+ if (WARN_ON_ONCE(!PageLocked(page)))
+ return ERR_PTR(-EINVAL);

ctx = fscrypt_get_ctx(inode, gfp_flags);
if (IS_ERR(ctx))
@@ -318,8 +320,9 @@ EXPORT_SYMBOL(fscrypt_encrypt_page);
int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
unsigned int len, unsigned int offs, u64 lblk_num)
{
- if (!(inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES))
- BUG_ON(!PageLocked(page));
+ if (WARN_ON_ONCE(!PageLocked(page) &&
+ !(inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES)))
+ return -EINVAL;

return fscrypt_do_page_crypto(inode, FS_DECRYPT, lblk_num, page, page,
len, offs, GFP_NOFS);
--
2.20.1