From patchwork Wed Jun 24 21:56:58 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?q?Andreas_Gr=C3=BCnbacher?= X-Patchwork-Id: 6670811 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 62B9DC05AC for ; Wed, 24 Jun 2015 22:05:20 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 6B2FA20574 for ; Wed, 24 Jun 2015 22:05:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6FA3F2056E for ; Wed, 24 Jun 2015 22:05:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752949AbbFXWFQ (ORCPT ); Wed, 24 Jun 2015 18:05:16 -0400 Received: from mail-wi0-f179.google.com ([209.85.212.179]:37753 "EHLO mail-wi0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752145AbbFXV5p (ORCPT ); Wed, 24 Jun 2015 17:57:45 -0400 Received: by wicgi11 with SMTP id gi11so58833349wic.0; Wed, 24 Jun 2015 14:57:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:subject:date:message-id:in-reply-to:references; bh=3eShk03oYZu2wkf5CFgdt7Mt9eHA7Pll0vMS/vv5ch4=; b=K45HSz1bYgegW/dDHjw1dgQZ1Cr5ePVhsNaE3W1Q4IawY8Z0oh+LRVTVGPYzjzDAYC 4huVp2900pWey5TJkyjYO6h5bvF4oa/Az7sW1/iEoUxG+XNukVmLzOaERz/OMrJo8r72 l1EFX/EsuRGMQQKPWwsPq0HWHsg/fcnbrYwK1yQgYclorguFMdFJa4mDDLa3tKeUNG5+ DzSI9N9tC38zPnpCC2NqbkR01iLCo0FSeOLYMYfch4XTwIBeZCrRSz+dJ9UtcqnW8WJJ SJwbFe3vuQZtMf07jex399TfYL9pfBiQiEE63D+lvmuWYWdWx7KXuBecugIyP0ae45Rp 6vGg== X-Received: by 10.194.222.137 with SMTP id qm9mr75227670wjc.43.1435183063387; Wed, 24 Jun 2015 14:57:43 -0700 (PDT) Received: from nuc.home.com (80-110-112-232.cgn.dynamic.surfer.at. [80.110.112.232]) by mx.google.com with ESMTPSA id lu5sm42559880wjb.9.2015.06.24.14.57.42 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 24 Jun 2015 14:57:42 -0700 (PDT) From: Andreas Gruenbacher X-Google-Original-From: Andreas Gruenbacher To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-api@vger.kernel.org, samba-technical@lists.samba.org, linux-security-module@vger.kernel.org Subject: [RFC v4 09/31] richacl: Update the file masks in chmod() Date: Wed, 24 Jun 2015 23:56:58 +0200 Message-Id: <1435183040-22726-10-git-send-email-agruenba@redhat.com> X-Mailer: git-send-email 2.4.2 In-Reply-To: <1435183040-22726-1-git-send-email-agruenba@redhat.com> References: <1435183040-22726-1-git-send-email-agruenba@redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Spam-Status: No, score=-5.7 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, SUSPICIOUS_RECIPS, T_DKIM_INVALID,UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org 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 --- fs/richacl_base.c | 40 ++++++++++++++++++++++++++++++++++++++++ include/linux/richacl.h | 1 + 2 files changed, 41 insertions(+) diff --git a/fs/richacl_base.c b/fs/richacl_base.c index fda0568..162794b 100644 --- a/fs/richacl_base.c +++ b/fs/richacl_base.c @@ -325,3 +325,43 @@ restart: acl->a_flags &= ~RICHACL_MASKED; } EXPORT_SYMBOL_GPL(richacl_compute_max_masks); + +/** + * richacl_chmod - update the file masks to reflect the new mode + * @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. + */ +struct richacl * +richacl_chmod(struct richacl *acl, mode_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)) + return acl; + + clone = richacl_clone(acl, GFP_KERNEL); + richacl_put(acl); + if (!clone) + return ERR_PTR(-ENOMEM); + + clone->a_flags |= RICHACL_MASKED; + clone->a_owner_mask = owner_mask; + clone->a_group_mask = group_mask; + clone->a_other_mask = other_mask; + + return clone; +} +EXPORT_SYMBOL_GPL(richacl_chmod); diff --git a/include/linux/richacl.h b/include/linux/richacl.h index 3cea47a..c2a10b5 100644 --- a/include/linux/richacl.h +++ b/include/linux/richacl.h @@ -301,5 +301,6 @@ extern int richacl_masks_to_mode(const struct richacl *); extern unsigned int richacl_mode_to_mask(mode_t); extern unsigned int richacl_want_to_mask(unsigned int); extern void richacl_compute_max_masks(struct richacl *, kuid_t); +extern struct richacl *richacl_chmod(struct richacl *, mode_t); #endif /* __RICHACL_H */