From patchwork Wed Jun 24 21:57:15 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: 6670241 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 D1AB8C05AD for ; Wed, 24 Jun 2015 21:58:40 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id CE89C2052F for ; Wed, 24 Jun 2015 21:58:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CAC1C20547 for ; Wed, 24 Jun 2015 21:58:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752644AbbFXV6d (ORCPT ); Wed, 24 Jun 2015 17:58:33 -0400 Received: from mail-wi0-f172.google.com ([209.85.212.172]:34247 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751578AbbFXV6L (ORCPT ); Wed, 24 Jun 2015 17:58:11 -0400 Received: by wicnd19 with SMTP id nd19so1117281wic.1; Wed, 24 Jun 2015 14:58:08 -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=wWYwJ9982ll5GU6zwgt95vpGYxb0d0AxLZ/38G2MpRI=; b=iblKOBt6p00ksz0ZL0gY6glFr4CmrAlQpkrJrR76U+Mg+rHf7fwnlHT/KWVdefDcNs IxH/N/A4ArBiDMfywJCkUG6K3TJMMMLDfc34NDkOzGcbaisXPOkH1spUKcklV4d5Z/0T UKUvVHq0JlLx+p8ruzHbGudqW/pfz/jNDcS1rTIXBEyB/x/Tef8/kovi9nPoO3sueYQc u5lj4frQOA8fFVXIx39Q15XzvnZDGI5+SWNRymHt5Vy/Mo+XF5CRijouwppGcvQX2C7I RanSZTh3FbENoqARiLxjEs9ca8T7H9dEFpaMzmAi7SiMHBH0050IyK6zaJZk/vjC/uJg IsXw== X-Received: by 10.180.198.198 with SMTP id je6mr8750562wic.82.1435183088275; Wed, 24 Jun 2015 14:58:08 -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.9.2015.06.24.14.58.07 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 24 Jun 2015 14:58:07 -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 Cc: Andreas Gruenbacher Subject: [RFC v4 26/31] richacl: Apply the file masks to a richacl Date: Wed, 24 Jun 2015 23:57:15 +0200 Message-Id: <1435183040-22726-27-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=-8.2 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 Put all the pieces of the acl transformation puzzle together for computing a richacl which has the file masks "applied" so that the standard nfsv4 access check algorithm can be used on the richacl. Signed-off-by: Andreas Gruenbacher --- fs/richacl_compat.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/richacl.h | 3 ++ 2 files changed, 113 insertions(+) diff --git a/fs/richacl_compat.c b/fs/richacl_compat.c index ae10fa6..c9c33df 100644 --- a/fs/richacl_compat.c +++ b/fs/richacl_compat.c @@ -708,3 +708,113 @@ richacl_isolate_group_class(struct richacl_alloc *alloc) } return 0; } + +/** + * __richacl_apply_masks - apply the file masks to all aces + * @alloc: acl and number of allocated entries + * + * Apply the owner mask to owner@ aces, the other mask to + * everyone@ aces, and the group mask to all other aces. + * + * The previous transformations have brought the acl into a + * form in which applying the masks will not lead to the + * accidental loss of permissions anymore. + */ +static int +__richacl_apply_masks(struct richacl_alloc *alloc, kuid_t owner) +{ + struct richace *ace; + + richacl_for_each_entry(ace, alloc->acl) { + unsigned int mask; + + if (richace_is_inherit_only(ace) || !richace_is_allow(ace) || + richace_is_owner(ace)) + continue; + if (richace_is_unix_user(ace) && uid_eq(owner, ace->e_id.uid)) + mask = alloc->acl->a_owner_mask; + else if (richace_is_everyone(ace)) + mask = alloc->acl->a_other_mask; + else + mask = alloc->acl->a_group_mask; + if (richace_change_mask(alloc, &ace, ace->e_mask & mask)) + return -1; + } + return 0; +} + +/** + * richacl_apply_masks - apply the masks to the acl + * + * Transform @acl so that the standard NFSv4 permission check algorithm (which + * is not aware of file masks) will compute the same access decisions as the + * richacl permission check algorithm (which looks at the acl and the file + * masks). + * + * This algorithm is split into several steps: + * + * - Move everyone@ aces to the end of the acl. This simplifies the other + * transformations, and allows the everyone@ allow ace at the end of the + * acl to eventually allow permissions to the other class only. + * + * - Propagate everyone@ permissions up the acl. This transformation makes + * sure that the owner and group class aces won't lose any permissions when + * we apply the other mask to the everyone@ allow ace at the end of the acl. + * + * - Apply the file masks to all aces. + * + * - Make sure the owner is granted the owner mask permissions. + * + * - Make sure everyone is granted the other mask permissions. + * + * - Make sure that the owner is not granted any permissions beyond the owner + * mask from group class aces or from everyone@. + * + * - Make sure that the group class is not granted any permissions from + * everyone@. + * + * The algorithm is exact except for richacls which cannot be represented as an + * acl alone: for example, given this acl: + * + * group@:rw::allow + * + * when file masks corresponding to mode 0600 are applied, the owner would only + * get rw access if he is a member of the owning group. This algorithm would + * produce an empty acl in this case. We fix this case by modifying + * richacl_permission() so that the group mask is always applied to group class + * aces. With this fix, the owner would not have any access (beyond the + * implicit permissions always granted to owners). + * + * NOTE: Depending on the acl and file masks, this algorithm can increase the + * number of aces by almost a factor of three in the worst case. This may make + * the acl too large for some purposes. + */ +int +richacl_apply_masks(struct richacl **acl, kuid_t owner) +{ + if ((*acl)->a_flags & RICHACL_MASKED) { + struct richacl_alloc alloc = { + .acl = richacl_clone(*acl, GFP_KERNEL), + .count = (*acl)->a_count, + }; + if (!alloc.acl) + return -ENOMEM; + + if (richacl_move_everyone_aces_down(&alloc) || + richacl_propagate_everyone(&alloc) || + __richacl_apply_masks(&alloc, owner) || + richacl_set_owner_permissions(&alloc) || + richacl_set_other_permissions(&alloc) || + richacl_isolate_owner_class(&alloc) || + richacl_isolate_group_class(&alloc)) { + richacl_put(alloc.acl); + return -ENOMEM; + } + + alloc.acl->a_flags &= ~RICHACL_MASKED; + richacl_put(*acl); + *acl = alloc.acl; + } + return 0; +} +EXPORT_SYMBOL_GPL(richacl_apply_masks); diff --git a/include/linux/richacl.h b/include/linux/richacl.h index 4ccd6fb..3d1af44 100644 --- a/include/linux/richacl.h +++ b/include/linux/richacl.h @@ -335,4 +335,7 @@ extern struct richacl *richacl_inherit(const struct richacl *, int); extern int richacl_permission(struct inode *, const struct richacl *, int); extern struct richacl *richacl_create(struct inode *, struct inode *); +/* richacl_compat.c */ +extern int richacl_apply_masks(struct richacl **, kuid_t); + #endif /* __RICHACL_H */