From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f182.google.com ([209.85.192.182]:34828 "EHLO mail-pf0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751474AbcIHSVe (ORCPT ); Thu, 8 Sep 2016 14:21:34 -0400 Received: by mail-pf0-f182.google.com with SMTP id w87so20602301pfk.2 for ; Thu, 08 Sep 2016 11:21:04 -0700 (PDT) Date: Thu, 8 Sep 2016 11:20:56 -0700 From: Eric Biggers To: linux-fsdevel@vger.kernel.org Cc: linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, tytso@mit.edu, jaegeuk@kernel.org Subject: Re: [PATCH] fscrypto: add authorization check for setting encryption policy Message-ID: <20160908182056.GC132970@google.com> References: <1473357429-134444-1-git-send-email-ebiggers@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1473357429-134444-1-git-send-email-ebiggers@google.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: (Fixing Cc list: the F2FS mailing list is linux-f2fs-devel@lists.sourceforge.net, not linux-f2fs@vger.kernel.org.) On Thu, Sep 08, 2016 at 10:57:08AM -0700, Eric Biggers wrote: > 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 >