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Date: Mon, 28 Dec 2020 10:54:33 -0800 From: Eric Biggers <ebiggers@...nel.org> To: stable@...r.kernel.org Cc: linux-fscrypt@...r.kernel.org, linux-ext4@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net, linux-mtd@...ts.infradead.org Subject: [PATCH 5.4 4/4] ubifs: prevent creating duplicate encrypted filenames From: Eric Biggers <ebiggers@...gle.com> 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@...r.kernel.org Link: https://lore.kernel.org/r/20201118075609.120337-5-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@...gle.com> --- 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
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