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ubifs: prevent creating duplicate encrypted filenames

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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: f4f61d2cc6 ("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>
This commit is contained in:
Eric Biggers 2020-11-17 23:56:08 -08:00
parent bfc2b7e851
commit 76786a0f08
1 changed files with 13 additions and 4 deletions
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17
fs/ubifs/dir.c
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@ -270,6 +270,15 @@ done:
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;