The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 76786a0f083473de31678bdb259a3d4167cf756d Mon Sep 17 00:00:00 2001
From: Eric Biggers ebiggers@google.com Date: Tue, 17 Nov 2020 23:56:08 -0800 Subject: [PATCH] ubifs: prevent creating duplicate encrypted filenames
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 Signed-off-by: Eric Biggers ebiggers@google.com
diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c index 155521e51ac5..08fde777c324 100644 --- a/fs/ubifs/dir.c +++ b/fs/ubifs/dir.c @@ -270,6 +270,15 @@ 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) { @@ -293,7 +302,7 @@ 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;
@@ -953,7 +962,7 @@ 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;
@@ -1038,7 +1047,7 @@ 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; @@ -1122,7 +1131,7 @@ 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;