From: Eric Biggers Date: Wed, 18 Nov 2020 07:56:06 +0000 (-0800) Subject: ext4: prevent creating duplicate encrypted filenames X-Git-Tag: rel_imx_5.10.35_2.0.0-somdevices.0~492^2~9 X-Git-Url: https://git.somdevices.com/?a=commitdiff_plain;h=e5a2a002f83d0bf6b1972cf20c5359c50dda471c;p=linux.git ext4: prevent creating duplicate encrypted filenames 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 Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 33509266f5a0..793fc7db9d28 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -2195,6 +2195,9 @@ 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 (sb_has_strict_encoding(sb) && IS_CASEFOLDED(dir) && sb->s_encoding && utf8_validate(sb->s_encoding, &dentry->d_name))