From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f177.google.com ([209.85.192.177]:35303 "EHLO mail-pf0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758071AbcIHR6P (ORCPT ); Thu, 8 Sep 2016 13:58:15 -0400 Received: by mail-pf0-f177.google.com with SMTP id w87so20430658pfk.2 for ; Thu, 08 Sep 2016 10:58:14 -0700 (PDT) From: Eric Biggers To: linux-fsdevel@vger.kernel.org Cc: linux-ext4@vger.kernel.org, linux-f2fs@vger.kernel.org, tytso@mit.edu, jaegeuk@kernel.org, Eric Biggers Subject: [PATCH] fscrypto: add authorization check for setting encryption policy Date: Thu, 8 Sep 2016 10:57:08 -0700 Message-Id: <1473357429-134444-1-git-send-email-ebiggers@google.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On an ext4 or f2fs filesystem with file encryption supported, a user could set an encryption policy on any empty directory(*) to which they had readonly access. This is obviously problematic, since such a directory might be owned by another user and the new encryption policy would prevent that other user from creating files in their own directory (for example). Fix this by requiring inode_owner_or_capable() permission to set an encryption policy. This means that either the caller must own the file, or the caller must have the capability CAP_FOWNER. (*) Or also on any regular file, for f2fs v4.6 and later and ext4 v4.8-rc1 and later; a separate bug fix is coming for that. Signed-off-by: Eric Biggers Cc: stable@vger.kernel.org # 4.1+; check fs/{ext4,f2fs} --- fs/crypto/policy.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c index 0f9961e..c9800b1 100644 --- a/fs/crypto/policy.c +++ b/fs/crypto/policy.c @@ -95,6 +95,9 @@ static int create_encryption_context_from_policy(struct inode *inode, int fscrypt_process_policy(struct inode *inode, const struct fscrypt_policy *policy) { + if (!inode_owner_or_capable(inode)) + return -EACCES; + if (policy->version != 0) return -EINVAL; -- 2.8.0.rc3.226.g39d4020