From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932992AbcGLLhF (ORCPT ); Tue, 12 Jul 2016 07:37:05 -0400 Received: from mail-qt0-f176.google.com ([209.85.216.176]:34603 "EHLO mail-qt0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753563AbcGLLhA (ORCPT ); Tue, 12 Jul 2016 07:37:00 -0400 Message-ID: <1468323416.7798.7.camel@redhat.com> Subject: Re: [PATCH v23 14/22] richacl: Update the file masks in chmod() From: Jeff Layton To: Andreas Gruenbacher , Alexander Viro Cc: Christoph Hellwig , "Theodore Ts'o" , Andreas Dilger , "J. Bruce Fields" , Trond Myklebust , Anna Schumaker , Dave Chinner , linux-ext4@vger.kernel.org, xfs@oss.sgi.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, linux-api@vger.kernel.org Date: Tue, 12 Jul 2016 07:36:56 -0400 In-Reply-To: <1467294433-3222-15-git-send-email-agruenba@redhat.com> References: <1467294433-3222-1-git-send-email-agruenba@redhat.com> <1467294433-3222-15-git-send-email-agruenba@redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.20.3 (3.20.3-1.fc24) Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2016-06-30 at 15:47 +0200, Andreas Gruenbacher wrote: > Doing a chmod() sets the file mode, which includes the file permission > bits.  When a file has a richacl, the permissions that the richacl > grants need to be limited to what the new file permission bits allow. > > This is done by setting the file masks in the richacl to what the file > permission bits map to.  The richacl access check algorithm takes the > file masks into account, which ensures that the richacl cannot grant too > many permissions. > > It is possible to explicitly add permissions to the file masks which go > beyond what the file permission bits can grant (like the > RICHACE_WRITE_ACL permission).  The POSIX.1 standard calls this an > alternate file access control mechanism.  A subsequent chmod() would > ensure that those permissions are disabled again. > > Signed-off-by: Andreas Gruenbacher > Reviewed-by: J. Bruce Fields > --- >  fs/richacl.c            | 71 +++++++++++++++++++++++++++++++++++++++++++++++++ >  include/linux/richacl.h |  1 + >  2 files changed, 72 insertions(+) > > diff --git a/fs/richacl.c b/fs/richacl.c > index b2a03c1..ba110a6 100644 > --- a/fs/richacl.c > +++ b/fs/richacl.c > @@ -547,3 +547,74 @@ out: >   return denied ? -EACCES : 0; >  } >  EXPORT_SYMBOL_GPL(richacl_permission); > + > +/** > + * __richacl_chmod  -  update the file masks to reflect the new mode > + * @acl: access control list > + * @mode: new file permission bits including the file type > + * > + * Return a copy of @acl where the file masks have been replaced by the file > + * masks corresponding to the file permission bits in @mode, or returns @acl > + * itself if the file masks are already up to date.  Takes over a reference > + * to @acl. > + */ > +static struct richacl * > +__richacl_chmod(struct richacl *acl, umode_t mode) > +{ > + unsigned int x = S_ISDIR(mode) ? 0 : RICHACE_DELETE_CHILD; > + unsigned int owner_mask, group_mask, other_mask; > + struct richacl *clone; > + > + owner_mask = richacl_mode_to_mask(mode >> 6) & ~x; > + group_mask = richacl_mode_to_mask(mode >> 3) & ~x; > + other_mask = richacl_mode_to_mask(mode)      & ~x; > + > + if (acl->a_owner_mask == owner_mask && > +     acl->a_group_mask == group_mask && > +     acl->a_other_mask == other_mask && > +     (acl->a_flags & RICHACL_MASKED) && > +     (acl->a_flags & RICHACL_WRITE_THROUGH)) > + return acl; > + > + clone = richacl_clone(acl, GFP_KERNEL); > + richacl_put(acl); > + if (!clone) > + return ERR_PTR(-ENOMEM); > + > + clone->a_flags |= (RICHACL_WRITE_THROUGH | RICHACL_MASKED); > + clone->a_owner_mask = owner_mask; > + clone->a_group_mask = group_mask; > + clone->a_other_mask = other_mask; > + > + return clone; > +} > + > +/** > + * richacl_chmod  -  filesystem chmod helper > + * @inode: inode whose file permission bits to change > + * @mode: new file permission bits including the file type > + * > + * Helper for filesystems to use to perform a chmod on the richacl of an inode. > + */ > +int > +richacl_chmod(struct inode *inode, umode_t mode) > +{ > + struct richacl *acl; > + int retval; > + > + if (S_ISLNK(mode)) > + return -EOPNOTSUPP; > + if (!inode->i_op->set_richacl) > + return -EOPNOTSUPP; > + acl = get_richacl(inode); > + if (IS_ERR_OR_NULL(acl)) > + return PTR_ERR(acl); > + acl = __richacl_chmod(acl, mode); > + if (IS_ERR(acl)) > + return PTR_ERR(acl); > + retval = inode->i_op->set_richacl(inode, acl); > + richacl_put(acl); > + > + return retval; > +} > +EXPORT_SYMBOL(richacl_chmod); > diff --git a/include/linux/richacl.h b/include/linux/richacl.h > index 3e05c94..db82fab 100644 > --- a/include/linux/richacl.h > +++ b/include/linux/richacl.h > @@ -190,5 +190,6 @@ extern unsigned int richacl_mode_to_mask(umode_t); >  extern unsigned int richacl_want_to_mask(unsigned int); >  extern void richacl_compute_max_masks(struct richacl *); >  extern int richacl_permission(struct inode *, const struct richacl *, int); > +extern int richacl_chmod(struct inode *, umode_t); >   >  #endif /* __RICHACL_H */ Acked-by: Jeff Layton