[PATCH AUTOSEL 5.2 044/249] fscrypt: clean up some BUG_ON()s in block encryption/decryption

From: Sasha Levin
Date: Mon Jul 15 2019 - 09:49:21 EST


From: Eric Biggers <ebiggers@xxxxxxxxxx>

[ 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@xxxxxxxxxxxxx>
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 335a362ee446..6f753198eeef 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -154,7 +154,10 @@ 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;

fscrypt_generate_iv(&iv, lblk_num, ci);

@@ -238,8 +241,6 @@ 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,
@@ -251,7 +252,8 @@ 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(gfp_flags);
if (IS_ERR(ctx))
@@ -299,8 +301,9 @@ 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