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| author | Eric Biggers <ebiggers@kernel.org> | 2026-07-12 22:36:55 -0400 |
|---|---|---|
| committer | Eric Biggers <ebiggers@kernel.org> | 2026-07-20 10:39:25 -0700 |
| commit | b69664873f4af302c7867aa7478e818549932614 (patch) | |
| tree | af8bfd51dc5a596488b1d3c037318746f7019da2 /fs/crypto | |
| parent | 95b39df0413077b631cde9c6e35224c15258ccf5 (diff) | |
| download | linux-next-b69664873f4af302c7867aa7478e818549932614.tar.gz linux-next-b69664873f4af302c7867aa7478e818549932614.zip | |
fscrypt: Fully disallow IV_INO_LBLK_32 with s_blocksize != PAGE_SIZE
FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32 with s_blocksize != PAGE_SIZE works
only with the fs-layer implementation of file contents encryption, not
blk-crypto. This is a problem for standardizing on blk-crypto.
Fortunately, no one should be using this combination anyway. It doesn't
make sense because the entire point of IV_INO_LBLK_32 is to support
inline encryption hardware that is limited to 32-bit DUNs.
Thus, fully disallow IV_INO_LBLK_32 with s_blocksize != PAGE_SIZE.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260713023708.9245-5-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Diffstat (limited to 'fs/crypto')
| -rw-r--r-- | fs/crypto/inline_crypt.c | 13 | ||||
| -rw-r--r-- | fs/crypto/policy.c | 17 |
2 files changed, 17 insertions, 13 deletions
diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c index 013f2bdc6f23..118e29ccb1d7 100644 --- a/fs/crypto/inline_crypt.c +++ b/fs/crypto/inline_crypt.c @@ -105,19 +105,6 @@ int fscrypt_select_encryption_impl(struct fscrypt_inode_info *ci, return 0; /* - * When a page contains multiple logically contiguous filesystem blocks, - * some filesystem code only calls fscrypt_mergeable_bio() for the first - * block in the page. This is fine for most of fscrypt's IV generation - * strategies, where contiguous blocks imply contiguous IVs. But it - * doesn't work with IV_INO_LBLK_32. For now, simply exclude - * IV_INO_LBLK_32 with blocksize != PAGE_SIZE from inline encryption. - */ - if ((fscrypt_policy_flags(&ci->ci_policy) & - FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) && - sb->s_blocksize != PAGE_SIZE) - return 0; - - /* * On all the filesystem's block devices, blk-crypto must support the * crypto configuration that the file would use. */ diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c index f40fb5924e75..a7322dba7557 100644 --- a/fs/crypto/policy.c +++ b/fs/crypto/policy.c @@ -177,6 +177,23 @@ static bool supported_iv_ino_lblk_policy(const struct fscrypt_policy_v2 *policy, type, sb->s_id); return false; } + + /* + * IV_INO_LBLK_32 isn't compatible with inline encryption when + * s_blocksize != PAGE_SIZE. In that case the DUN can wrap around in + * the middle of a page, but sometimes fscrypt_mergeable_bio() is called + * only for the first block per page. Since IV_INO_LBLK_32 exists only + * to support inline encryption hardware that is limited to 32-bit DUNs, + * just disallow IV_INO_LBLK_32 with s_blocksize != PAGE_SIZE entirely. + */ + if ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) && + sb->s_blocksize != PAGE_SIZE) { + fscrypt_warn(inode, + "Can't use %s policy on filesystem '%s' with block size != PAGE_SIZE", + type, sb->s_id); + return false; + } + return true; } |