From patchwork Wed Feb 25 23:41:31 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: 5885661 Return-Path: X-Original-To: patchwork-linux-nfs@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 A33B59F54F for ; Wed, 25 Feb 2015 23:46:29 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id BE97420268 for ; Wed, 25 Feb 2015 23:46:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AC14120381 for ; Wed, 25 Feb 2015 23:46:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932308AbbBYXqG (ORCPT ); Wed, 25 Feb 2015 18:46:06 -0500 Received: from mail-we0-f180.google.com ([74.125.82.180]:34797 "EHLO mail-we0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753852AbbBYXmV (ORCPT ); Wed, 25 Feb 2015 18:42:21 -0500 Received: by wesq59 with SMTP id q59so6811382wes.1; Wed, 25 Feb 2015 15:42:20 -0800 (PST) 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:in-reply-to :references; bh=gToWfdlEfeXvEgVFkQv/JWAyd9JXM6Jzt5V23YiBurE=; b=qupy1eHbGbsLYzTmV2tgNEuVL7YNEBc8SVFZrs3fY5/5CmKrL/J0bXiNOIzG69liHq T9TV2ofnjoDnpwWUCZsXo4vbqtC+9vrTBbciw0Vip20L+aYlz/NfBAnqyBIMdEMgabdv Y7cNnFZwywlSLSrS9o5v+kGVzU3dUaY/15EehdEm34GbRX07mIz5FGdG0e7s92b1NVFk wTVaBR3x3L6bvgxdC4dyOJiuLHUdM3DO3WjEdws1fG4tak3lJ5aVyGtBRP96eiTD4L9w zr9e1MqGnW3KWKAqrD1D2wm0jmvm4m5ah7Nxu8zfRqtpab/GHuRRN5aeW5eSxMsLzyVt 8Grg== X-Received: by 10.180.198.78 with SMTP id ja14mr11168387wic.11.1424907740073; Wed, 25 Feb 2015 15:42:20 -0800 (PST) Received: from nuc.home.com (80-110-112-196.cgn.dynamic.surfer.at. [80.110.112.196]) by mx.google.com with ESMTPSA id vh8sm66946337wjc.12.2015.02.25.15.42.18 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 25 Feb 2015 15:42:19 -0800 (PST) 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 Subject: [RFC 10/21] richacl: Compute maximum file masks from an acl Date: Thu, 26 Feb 2015 00:41:31 +0100 Message-Id: X-Mailer: git-send-email 2.1.0 In-Reply-To: References: In-Reply-To: References: Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, T_DKIM_INVALID, T_RP_MATCHES_RCVD, 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 Compute upper bound owner, group, and other file masks with as few permissions as possible without denying any permissions that the NFSv4 acl in a richacl grants. This algorithm is used when a file inherits an acl at create time and when an acl is set via a mechanism that does not specify file modes (such as via nfsd). When user-space sets an acl, the file masks are passed in as part of the xattr. When setting a richacl, the file masks determine what the file permission bits will be set to; see richacl_masks_to_mode(). Signed-off-by: Andreas Gruenbacher --- fs/richacl_base.c | 128 ++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/richacl.h | 1 + 2 files changed, 129 insertions(+) diff --git a/fs/richacl_base.c b/fs/richacl_base.c index 83731c7..683bde2 100644 --- a/fs/richacl_base.c +++ b/fs/richacl_base.c @@ -172,3 +172,131 @@ richacl_want_to_mask(unsigned int want) return mask; } EXPORT_SYMBOL_GPL(richacl_want_to_mask); + +/** + * richacl_allowed_to_who - mask flags allowed to a specific who value + * + * Computes the mask values allowed to a specific who value, taking + * EVERYONE@ entries into account. + */ +static unsigned int richacl_allowed_to_who(struct richacl *acl, + struct richace *who) +{ + struct richace *ace; + unsigned int allowed = 0; + + richacl_for_each_entry_reverse(ace, acl) { + if (richace_is_inherit_only(ace)) + continue; + if (richace_is_same_identifier(ace, who) || + richace_is_everyone(ace)) { + if (richace_is_allow(ace)) + allowed |= ace->e_mask; + else if (richace_is_deny(ace)) + allowed &= ~ace->e_mask; + } + } + return allowed; +} + +/** + * richacl_group_class_allowed - maximum permissions the group class is allowed + * + * See richacl_compute_max_masks(). + */ +static unsigned int richacl_group_class_allowed(struct richacl *acl) +{ + struct richace *ace; + unsigned int everyone_allowed = 0, group_class_allowed = 0; + int had_group_ace = 0; + + richacl_for_each_entry_reverse(ace, acl) { + if (richace_is_inherit_only(ace) || + richace_is_owner(ace)) + continue; + + if (richace_is_everyone(ace)) { + if (richace_is_allow(ace)) + everyone_allowed |= ace->e_mask; + else if (richace_is_deny(ace)) + everyone_allowed &= ~ace->e_mask; + } else { + group_class_allowed |= + richacl_allowed_to_who(acl, ace); + + if (richace_is_group(ace)) + had_group_ace = 1; + } + } + if (!had_group_ace) + group_class_allowed |= everyone_allowed; + return group_class_allowed; +} + +/** + * richacl_compute_max_masks - compute upper bound masks + * + * Computes upper bound owner, group, and other masks so that none of + * the mask flags allowed by the acl are disabled (for any choice of the + * file owner or group membership). + */ +void richacl_compute_max_masks(struct richacl *acl) +{ + unsigned int gmask = ~0; + struct richace *ace; + + /* + * @gmask contains all permissions which the group class is ever + * allowed. We use it to avoid adding permissions to the group mask + * from everyone@ allow aces which the group class is always denied + * through other aces. For example, the following acl would otherwise + * result in a group mask or rw: + * + * group@:w::deny + * everyone@:rw::allow + * + * Avoid computing @gmask for acls which do not include any group class + * deny aces: in such acls, the group class is never denied any + * permissions from everyone@ allow aces. + */ + +restart: + acl->a_owner_mask = 0; + acl->a_group_mask = 0; + acl->a_other_mask = 0; + + richacl_for_each_entry_reverse(ace, acl) { + if (richace_is_inherit_only(ace)) + continue; + + if (richace_is_owner(ace)) { + if (richace_is_allow(ace)) + acl->a_owner_mask |= ace->e_mask; + else if (richace_is_deny(ace)) + acl->a_owner_mask &= ~ace->e_mask; + } else if (richace_is_everyone(ace)) { + if (richace_is_allow(ace)) { + acl->a_owner_mask |= ace->e_mask; + acl->a_group_mask |= ace->e_mask & gmask; + acl->a_other_mask |= ace->e_mask; + } else if (richace_is_deny(ace)) { + acl->a_owner_mask &= ~ace->e_mask; + acl->a_group_mask &= ~ace->e_mask; + acl->a_other_mask &= ~ace->e_mask; + } + } else { + if (richace_is_allow(ace)) { + acl->a_owner_mask |= ace->e_mask & gmask; + acl->a_group_mask |= ace->e_mask & gmask; + } else if (richace_is_deny(ace) && gmask == ~0) { + gmask = richacl_group_class_allowed(acl); + if (likely(gmask != ~0)) + /* should always be true */ + goto restart; + } + } + } + + acl->a_flags &= ~ACL4_MASKED; +} +EXPORT_SYMBOL_GPL(richacl_compute_max_masks); diff --git a/include/linux/richacl.h b/include/linux/richacl.h index 41819f4..05d79ac 100644 --- a/include/linux/richacl.h +++ b/include/linux/richacl.h @@ -290,5 +290,6 @@ extern struct richacl *richacl_alloc(int); 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 *); #endif /* __RICHACL_H */