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Commit 5664f1cb authored by Eric Biggers's avatar Eric Biggers Committed by Greg Kroah-Hartman
Browse files

ubifs: prevent creating duplicate encrypted filenames 

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: f4f61d2c ("ubifs: Implement encrypted filenames")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201118075609.120337-5-ebiggers@kernel.org


Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 218cf245

fs/ubifs/dir.c

+13 −4
Original line number Diff line number Diff line
@@ -290,6 +290,15 @@ 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)

{
@@ -313,7 +322,7 @@ 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;
@@ -977,7 +986,7 @@ 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;
@@ -1062,7 +1071,7 @@ 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;
@@ -1146,7 +1155,7 @@ 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;