From patchwork Tue Aug 4 11:53:07 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: 6938111 Return-Path: X-Original-To: patchwork-cifs-client@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 84B2DC05AD for ; Tue, 4 Aug 2015 12:10:53 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 0638420395 for ; Tue, 4 Aug 2015 12:10:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0FF60203E1 for ; Tue, 4 Aug 2015 12:10:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933802AbbHDMKN (ORCPT ); Tue, 4 Aug 2015 08:10:13 -0400 Received: from mail-wi0-f170.google.com ([209.85.212.170]:37458 "EHLO mail-wi0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933423AbbHDLyr (ORCPT ); Tue, 4 Aug 2015 07:54:47 -0400 Received: by wibud3 with SMTP id ud3so20323324wib.0; Tue, 04 Aug 2015 04:54:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=lOFeRZFNYP2ncZQJ71877sfK6+DHK3DCDDWEFA+XG4U=; b=XvES59IOjNAg9CDKuTPJSn0ySu/8UvieFVRDizwpViGH6Vcg/arf/Rxse7YoXBYfMX lOawCYKu4sPiS2S/SxmJp7WQrParY74ncRvVyPqzTXmbVcdLHDZIi8/z59C//0i5lH10 YuqQEBUldwYQZSvscUdZjAZFrnRoOe6gvhiJwsj1P96xdAEqpLJoVPmdKlLOFH6RFLCQ HQQxoqmBz26Dv4vbfBEA/GJs+bZGoxui3/uhJXjp+bkCYbT0QQvA53fP6YQfnrier8Za U/EN04lCERwgww5Nu/EmxC4aTOYADMvohQu7bFOTEejTl5pvrD7bJ6POL3b5G2x5Q0m0 SZyA== X-Received: by 10.180.91.132 with SMTP id ce4mr39971540wib.45.1438689285581; Tue, 04 Aug 2015 04:54:45 -0700 (PDT) Received: from schleppi.home.com (p54980F84.dip0.t-ipconnect.de. [84.152.15.132]) by smtp.gmail.com with ESMTPSA id u7sm2018458wif.3.2015.08.04.04.54.43 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 04 Aug 2015 04:54:44 -0700 (PDT) From: Andreas Gruenbacher X-Google-Original-From: Andreas Gruenbacher To: linux-kernel@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-api@vger.kernel.org, linux-cifs@vger.kernel.org, linux-security-module@vger.kernel.org, Andreas Gruenbacher Subject: [RFC v6 09/40] richacl: Update the file masks in chmod() Date: Tue, 4 Aug 2015 13:53:07 +0200 Message-Id: <1438689218-6921-10-git-send-email-agruenba@redhat.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1438689218-6921-1-git-send-email-agruenba@redhat.com> References: <1438689218-6921-1-git-send-email-agruenba@redhat.com> Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org X-Spam-Status: No, score=-4.4 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=unavailable 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 8426600..fd81158 100644 --- a/fs/richacl_base.c +++ b/fs/richacl_base.c @@ -338,3 +338,43 @@ 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 + * @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_WRITE_THROUGH | 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 3d719db..8df6d93 100644 --- a/include/linux/richacl.h +++ b/include/linux/richacl.h @@ -304,5 +304,6 @@ 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 */