From 4afb9996a254a8ec33801f4b33992d45670164b2 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Tue, 13 Jun 2017 16:47:55 -0700 Subject: [PATCH] ubifs: require key for truncate(2) of encrypted file Currently, filesystems allow truncate(2) on an encrypted file without the encryption key. However, it's impossible to correctly handle the case where the size being truncated to is not a multiple of the filesystem block size, because that would require decrypting the final block, zeroing the part beyond i_size, then encrypting the block. As other modifications to encrypted file contents are prohibited without the key, just prohibit truncate(2) as well, making it fail with ENOKEY. Signed-off-by: Eric Biggers Signed-off-by: Richard Weinberger --- fs/ubifs/file.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c index 2cda3d67e2d0..ee3ff4c6bf4a 100644 --- a/fs/ubifs/file.c +++ b/fs/ubifs/file.c @@ -1284,6 +1284,14 @@ int ubifs_setattr(struct dentry *dentry, struct iattr *attr) if (err) return err; + if (ubifs_crypt_is_encrypted(inode) && (attr->ia_valid & ATTR_SIZE)) { + err = fscrypt_get_encryption_info(inode); + if (err) + return err; + if (!fscrypt_has_encryption_key(inode)) + return -ENOKEY; + } + if ((attr->ia_valid & ATTR_SIZE) && attr->ia_size < inode->i_size) /* Truncation to a smaller size */ err = do_truncation(c, inode, attr); -- 2.20.1