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))