From patchwork Wed Jul 22 13:02:59 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: 6843791 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 421219F1D4 for ; Wed, 22 Jul 2015 13:22:27 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 52E08206D0 for ; Wed, 22 Jul 2015 13:22:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 22D3F206D7 for ; Wed, 22 Jul 2015 13:22:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757476AbbGVNVx (ORCPT ); Wed, 22 Jul 2015 09:21:53 -0400 Received: from mail-wi0-f179.google.com ([209.85.212.179]:33098 "EHLO mail-wi0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756659AbbGVNEP (ORCPT ); Wed, 22 Jul 2015 09:04:15 -0400 Received: by wicmv11 with SMTP id mv11so80725517wic.0; Wed, 22 Jul 2015 06:04:13 -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=090cYkMmwpdxz6/BCGnxHvYQO7BC+xR8HA5k2meNEcw=; b=qBVXrINKsHLMn3K5U2TEyVeCr30txvxft3BWmqLTvcov2yoHUZsbhbJ1wHo0r5DpNT dw518q3c4wibu8KZw30jzW8BJ2trzuUeSXbiCqpKrnSU2DBhQR5jVTao+UhatUjLUL8i mjWY4kUmi1aYvmkOmfe9CuglHr9+7XFPYbplh/dHAxfRAdmeWcF6z/bAzyD4tsOx9K+a yw71BqDj4If1dftUGgyCUldbfkzio+pXKVxfB5PxadCeNVt9pAC6plCGuJw3SSzBIzOk k8myIF3zYEaFf+8jUMdmt9nWlVAy+FoH7nVGYz/NZFQt65Q6P/wm4hPqILbDz/ZKiiMK JRpA== X-Received: by 10.180.75.243 with SMTP id f19mr29468668wiw.52.1437570253310; Wed, 22 Jul 2015 06:04:13 -0700 (PDT) Received: from schleppi.home.com ([149.14.88.26]) by smtp.gmail.com with ESMTPSA id u7sm21992628wif.3.2015.07.22.06.04.11 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 22 Jul 2015 06:04:12 -0700 (PDT) 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, samba-technical@lists.samba.org, linux-security-module@vger.kernel.org, Andreas Gruenbacher Subject: [PATCH v5 09/39] richacl: Update the file masks in chmod() Date: Wed, 22 Jul 2015 15:02:59 +0200 Message-Id: <1437570209-29832-10-git-send-email-andreas.gruenbacher@gmail.com> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1437570209-29832-1-git-send-email-andreas.gruenbacher@gmail.com> References: <1437570209-29832-1-git-send-email-andreas.gruenbacher@gmail.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=-8.0 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, 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 From: Andreas Gruenbacher 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 23e9824..e88cdda 100644 --- a/fs/richacl_base.c +++ b/fs/richacl_base.c @@ -334,3 +334,43 @@ 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 90baca3..e4266dd 100644 --- a/include/linux/richacl.h +++ b/include/linux/richacl.h @@ -302,5 +302,6 @@ 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 */