From patchwork Tue Aug 16 11:02:54 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andreas Gruenbacher X-Patchwork-Id: 9283483 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 6B6A060839 for ; Tue, 16 Aug 2016 11:05:27 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5A4772862E for ; Tue, 16 Aug 2016 11:05:27 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4EE3C2863F; Tue, 16 Aug 2016 11:05:27 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from oss.sgi.com (oss.sgi.com [192.48.182.195]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 22CCE2862E for ; Tue, 16 Aug 2016 11:05:26 +0000 (UTC) Received: from oss.sgi.com (localhost [IPv6:::1]) by oss.sgi.com (Postfix) with ESMTP id 4FCEC7CE2; Tue, 16 Aug 2016 06:04:23 -0500 (CDT) X-Original-To: xfs@oss.sgi.com Delivered-To: xfs@oss.sgi.com Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id 936D77CE1 for ; Tue, 16 Aug 2016 06:04:21 -0500 (CDT) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay1.corp.sgi.com (Postfix) with ESMTP id 36FBE8F8165 for ; Tue, 16 Aug 2016 04:04:21 -0700 (PDT) X-ASG-Debug-ID: 1471345459-0bf81563e41b6d0001-NocioJ Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by cuda.sgi.com with ESMTP id coxdaMeRsdvhE1kL (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Tue, 16 Aug 2016 04:04:20 -0700 (PDT) X-Barracuda-Envelope-From: agruenba@redhat.com X-Barracuda-Effective-Source-IP: mx1.redhat.com[209.132.183.28] X-Barracuda-Apparent-Source-IP: 209.132.183.28 X-ASG-Whitelist: Client Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9941083F47; Tue, 16 Aug 2016 11:04:19 +0000 (UTC) Received: from nux.redhat.com (vpn1-4-81.ams2.redhat.com [10.36.4.81]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u7GB34Ff006464; Tue, 16 Aug 2016 07:04:14 -0400 From: Andreas Gruenbacher To: Alexander Viro Subject: [PATCH v25 13/22] richacl: Update the file masks in chmod() Date: Tue, 16 Aug 2016 13:02:54 +0200 X-ASG-Orig-Subj: [PATCH v25 13/22] richacl: Update the file masks in chmod() Message-Id: <1471345383-15334-14-git-send-email-agruenba@redhat.com> In-Reply-To: <1471345383-15334-1-git-send-email-agruenba@redhat.com> References: <1471345383-15334-1-git-send-email-agruenba@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Tue, 16 Aug 2016 11:04:19 +0000 (UTC) X-Barracuda-Connect: mx1.redhat.com[209.132.183.28] X-Barracuda-Start-Time: 1471345460 X-Barracuda-Encrypted: ECDHE-RSA-AES256-GCM-SHA384 X-Barracuda-URL: https://192.48.157.11:443/cgi-mod/mark.cgi X-Barracuda-Scan-Msg-Size: 3996 X-Virus-Scanned: by bsmtpd at sgi.com X-Barracuda-BRTS-Status: 1 Cc: "J. Bruce Fields" , linux-nfs@vger.kernel.org, Theodore Ts'o , Andreas Gruenbacher , linux-cifs@vger.kernel.org, linux-api@vger.kernel.org, Trond Myklebust , linux-kernel@vger.kernel.org, xfs@oss.sgi.com, Christoph Hellwig , Andreas Dilger , linux-fsdevel@vger.kernel.org, Jeff Layton , linux-ext4@vger.kernel.org, Anna Schumaker X-BeenThere: xfs@oss.sgi.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com X-Virus-Scanned: ClamAV using ClamSMTP 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 Acked-by: Jeff Layton --- 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 731c468..a199245 100644 --- a/fs/richacl.c +++ b/fs/richacl.c @@ -541,3 +541,74 @@ restart: acl->a_flags &= ~(RICHACL_WRITE_THROUGH | RICHACL_MASKED); } EXPORT_SYMBOL_GPL(richacl_compute_max_masks); + +/** + * __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 207fe06..3cd5e53 100644 --- a/include/linux/richacl.h +++ b/include/linux/richacl.h @@ -189,5 +189,6 @@ extern int richacl_masks_to_mode(const struct richacl *); extern unsigned int richacl_mode_to_mask(umode_t); extern int richacl_permission(struct inode *, const struct richacl *, int); extern void richacl_compute_max_masks(struct richacl *); +extern int richacl_chmod(struct inode *, umode_t); #endif /* __RICHACL_H */