From patchwork Wed Jul 22 13:03:16 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: 6843151 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 E392C9F380 for ; Wed, 22 Jul 2015 13:12:05 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 005D0206CC for ; Wed, 22 Jul 2015 13:12:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E2CF7206B6 for ; Wed, 22 Jul 2015 13:12:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934300AbbGVNLr (ORCPT ); Wed, 22 Jul 2015 09:11:47 -0400 Received: from mail-wi0-f170.google.com ([209.85.212.170]:34289 "EHLO mail-wi0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756901AbbGVNEh (ORCPT ); Wed, 22 Jul 2015 09:04:37 -0400 Received: by wibud3 with SMTP id ud3so153272350wib.1; Wed, 22 Jul 2015 06:04:35 -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=f2k22LYGwsn8snfTvTvGMkQf9W27etecDVlgqor6TFE=; b=lKLzPamlzFQai0yA8swPjGRan2myMp0m2tOW/GSPDGO7uJqDeadDQgcgK+iiPWnk7E 1EElAdpGg0CX1YgOAdDx9gC1bNPOZyPJigtGiXaK2Kgx2eN0ld8R5yT0SvjQDktZJuvw U+UQ+01wFmHEYfYdGBBf34UvSF4GPkd7LhRnvRyq/7wyBr9rVcYtXaj9kGYQtYTOFPrO dB8TkwHOKU9BkYUikc/P/Gi7B+1aBainE6kmrfle9PDPrw2P2J4QyZrCluyls3QhqR5u D79E0GVUEBTjPwKs/xs8pK2E16TEJJn8H10XdUPuT0/yllPRD9wMAzrddQcPkIwNSeSt sBFA== X-Received: by 10.180.73.2 with SMTP id h2mr6597503wiv.72.1437570275518; Wed, 22 Jul 2015 06:04:35 -0700 (PDT) Received: from schleppi.home.com ([149.14.88.26]) by smtp.gmail.com with ESMTPSA id u7sm21992628wif.3.2015.07.22.06.04.34 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 22 Jul 2015 06:04:34 -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 , Andreas Gruenbacher Subject: [PATCH v5 26/39] richacl: Apply the file masks to a richacl Date: Wed, 22 Jul 2015 15:03:16 +0200 Message-Id: <1437570209-29832-27-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 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 f18f59c..05219ce 100644 --- a/fs/richacl_compat.c +++ b/fs/richacl_compat.c @@ -703,3 +703,113 @@ 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 49d7207..ef23581 100644 --- a/include/linux/richacl.h +++ b/include/linux/richacl.h @@ -336,4 +336,7 @@ 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 */