From: Eric Biggers <ebiggers@kernel.org>
To: stable@vger.kernel.org
Cc: linux-fscrypt@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net,
linux-mtd@lists.infradead.org
Subject: [PATCH 5.4 2/4] ext4: prevent creating duplicate encrypted filenames
Date: Mon, 28 Dec 2020 10:54:31 -0800 [thread overview]
Message-ID: <20201228185433.61129-3-ebiggers@kernel.org> (raw)
In-Reply-To: <20201228185433.61129-1-ebiggers@kernel.org>
From: Eric Biggers <ebiggers@google.com>
commit 75d18cd1868c2aee43553723872c35d7908f240f upstream.
As described in "fscrypt: add fscrypt_is_nokey_name()", it's possible to
create a duplicate filename in an encrypted directory by creating a file
concurrently with adding the directory's encryption key.
Fix this bug on ext4 by rejecting no-key dentries in ext4_add_entry().
Note that the duplicate check in ext4_find_dest_de() sometimes prevented
this bug. However in many cases it didn't, since ext4_find_dest_de()
doesn't examine every dentry.
Fixes: 4461471107b7 ("ext4 crypto: enable filename encryption")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201118075609.120337-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
fs/ext4/namei.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 36a81b57012a5..59038e361337c 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2192,6 +2192,9 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
if (!dentry->d_name.len)
return -EINVAL;
+ if (fscrypt_is_nokey_name(dentry))
+ return -ENOKEY;
+
#ifdef CONFIG_UNICODE
if (ext4_has_strict_mode(sbi) && IS_CASEFOLDED(dir) &&
sbi->s_encoding && utf8_validate(sbi->s_encoding, &dentry->d_name))
--
2.29.2
next prev parent reply other threads:[~2020-12-28 18:56 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-28 18:54 [PATCH 5.4 0/4] fscrypt: prevent creating duplicate encrypted filenames Eric Biggers
2020-12-28 18:54 ` [PATCH 5.4 1/4] fscrypt: add fscrypt_is_nokey_name() Eric Biggers
2020-12-28 18:54 ` Eric Biggers [this message]
2020-12-28 18:54 ` [PATCH 5.4 3/4] f2fs: prevent creating duplicate encrypted filenames Eric Biggers
2020-12-28 18:54 ` [PATCH 5.4 4/4] ubifs: " Eric Biggers
2020-12-30 15:39 ` [PATCH 5.4 0/4] fscrypt: " Greg KH
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