linux-kernel - [PATCH AUTOSEL 6.6 15/19] ecryptfs: Reject casefold directory inodes

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Date: Mon, 15 Jan 2024 20:05:10 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Gabriel Krisman Bertazi <krisman@...e.de>,
	Eric Biggers <ebiggers@...gle.com>,
	Sasha Levin <sashal@...nel.org>,
	code@...icks.com,
	brauner@...nel.org,
	dchinner@...hat.com,
	jack@...e.cz,
	jlayton@...nel.org,
	xiubli@...hat.com,
	stefanb@...ux.ibm.com,
	viro@...iv.linux.org.uk,
	ecryptfs@...r.kernel.org
Subject: [PATCH AUTOSEL 6.6 15/19] ecryptfs: Reject casefold directory inodes

From: Gabriel Krisman Bertazi <krisman@...e.de>

[ Upstream commit cd72c7ef5fed44272272a105b1da22810c91be69 ]

Even though it seems to be able to resolve some names of
case-insensitive directories, the lack of d_hash and d_compare means we
end up with a broken state in the d_cache.  Considering it was never a
goal to support these two together, and we are preparing to use
d_revalidate in case-insensitive filesystems, which would make the
combination even more broken, reject any attempt to get a casefolded
inode from ecryptfs.

Signed-off-by: Gabriel Krisman Bertazi <krisman@...e.de>
Reviewed-by: Eric Biggers <ebiggers@...gle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/ecryptfs/inode.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 5ab4b87888a7..795e9fe2f721 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -78,6 +78,14 @@ static struct inode *__ecryptfs_get_inode(struct inode *lower_inode,
 
 	if (lower_inode->i_sb != ecryptfs_superblock_to_lower(sb))
 		return ERR_PTR(-EXDEV);
+
+	/* Reject dealing with casefold directories. */
+	if (IS_CASEFOLDED(lower_inode)) {
+		pr_err_ratelimited("%s: Can't handle casefolded directory.\n",
+				   __func__);
+		return ERR_PTR(-EREMOTE);
+	}
+
 	if (!igrab(lower_inode))
 		return ERR_PTR(-ESTALE);
 	inode = iget5_locked(sb, (unsigned long)lower_inode,
-- 
2.43.0