linux-kernel - [PATCH] ext4: add casefolded file check

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Date: Thu, 30 May 2024 15:41:50 +0800
From: Lizhi Xu <lizhi.xu@...driver.com>
To: <syzbot+340581ba9dceb7e06fb3@...kaller.appspotmail.com>
CC: <coreteam@...filter.org>, <davem@...emloft.net>, <ebiggers@...nel.org>,
        <fw@...len.de>, <jaegeuk@...nel.org>, <kadlec@...filter.org>,
        <kuba@...nel.org>, <linux-fscrypt@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
        <netfilter-devel@...r.kernel.org>, <pablo@...filter.org>,
        <syzkaller-bugs@...glegroups.com>, <tytso@....edu>
Subject: [PATCH] ext4: add casefolded file check

The file name that needs to calculate the siphash must have both flags casefolded
and dir at the same time, so before calculating it, confirm that the flag meets
the conditions.

Reported-by: syzbot+340581ba9dceb7e06fb3@...kaller.appspotmail.com
Signed-off-by: Lizhi Xu <lizhi.xu@...driver.com>
---
 fs/ext4/hash.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/ext4/hash.c b/fs/ext4/hash.c
index deabe29da7fb..c8840cfc01dd 100644
--- a/fs/ext4/hash.c
+++ b/fs/ext4/hash.c
@@ -265,6 +265,10 @@ static int __ext4fs_dirhash(const struct inode *dir, const char *name, int len,
 		__u64	combined_hash;
 
 		if (fscrypt_has_encryption_key(dir)) {
+			if (!IS_CASEFOLDED(dir)) {
+				ext4_warning_inode(dir, "Siphash requires Casefolded file");
+				return -2;
+			}
 			combined_hash = fscrypt_fname_siphash(dir, &qname);
 		} else {
 			ext4_warning_inode(dir, "Siphash requires key");
-- 
2.43.0