[PATCH 5.4 4/4] ubifs: prevent creating duplicate encrypted filenames
From: Eric Biggers <ebiggers@kernel.org>
Date: 2020-12-28 18:56:11
Also in:
linux-f2fs-devel, linux-fscrypt, stable
Subsystem:
filesystems (vfs and infrastructure), the rest, ubi file system (ubifs) · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds, Richard Weinberger
From: Eric Biggers <redacted>
commit 76786a0f083473de31678bdb259a3d4167cf756d 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 ubifs by rejecting no-key dentries in ubifs_create(),
ubifs_mkdir(), ubifs_mknod(), and ubifs_symlink().
Note that ubifs doesn't actually report the duplicate filenames from
readdir, but rather it seems to replace the original dentry with a new
one (which is still wrong, just a different effect from ext4).
On ubifs, this fixes xfstest generic/595 as well as the new xfstest I
wrote specifically for this bug.
Fixes: f4f61d2cc6d8 ("ubifs: Implement encrypted filenames")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201118075609.120337-5-ebiggers@kernel.org (local)
Signed-off-by: Eric Biggers <redacted>
---
fs/ubifs/dir.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index 6c0e19f7a21f4..a5e5e9b9d4e31 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c@@ -278,6 +278,15 @@ static struct dentry *ubifs_lookup(struct inode *dir, struct dentry *dentry, return d_splice_alias(inode, dentry); } +static int ubifs_prepare_create(struct inode *dir, struct dentry *dentry, + struct fscrypt_name *nm) +{ + if (fscrypt_is_nokey_name(dentry)) + return -ENOKEY; + + return fscrypt_setup_filename(dir, &dentry->d_name, 0, nm); +} + static int ubifs_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool excl) {
@@ -301,7 +310,7 @@ static int ubifs_create(struct inode *dir, struct dentry *dentry, umode_t mode, if (err) return err; - err = fscrypt_setup_filename(dir, &dentry->d_name, 0, &nm); + err = ubifs_prepare_create(dir, dentry, &nm); if (err) goto out_budg;
@@ -961,7 +970,7 @@ static int ubifs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) if (err) return err; - err = fscrypt_setup_filename(dir, &dentry->d_name, 0, &nm); + err = ubifs_prepare_create(dir, dentry, &nm); if (err) goto out_budg;
@@ -1046,7 +1055,7 @@ static int ubifs_mknod(struct inode *dir, struct dentry *dentry, return err; } - err = fscrypt_setup_filename(dir, &dentry->d_name, 0, &nm); + err = ubifs_prepare_create(dir, dentry, &nm); if (err) { kfree(dev); goto out_budg;
@@ -1130,7 +1139,7 @@ static int ubifs_symlink(struct inode *dir, struct dentry *dentry, if (err) return err; - err = fscrypt_setup_filename(dir, &dentry->d_name, 0, &nm); + err = ubifs_prepare_create(dir, dentry, &nm); if (err) goto out_budg;
--
2.29.2