From patchwork Fri Mar 27 16:50:25 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: 6109971 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 CED08BF90F for ; Fri, 27 Mar 2015 16:56:33 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id D1F05203DA for ; Fri, 27 Mar 2015 16:56:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BC59C203AD for ; Fri, 27 Mar 2015 16:56:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754040AbbC0QwW (ORCPT ); Fri, 27 Mar 2015 12:52:22 -0400 Received: from mail-wi0-f179.google.com ([209.85.212.179]:38732 "EHLO mail-wi0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754019AbbC0QwS (ORCPT ); Fri, 27 Mar 2015 12:52:18 -0400 Received: by wibgn9 with SMTP id gn9so39220237wib.1; Fri, 27 Mar 2015 09:52:16 -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 :in-reply-to:references; bh=31GkcNx8n8d2LrQMnM60CPebC1CprG7MDI5jwWgP5yQ=; b=o8LcwHbZANYo4ImIhwjeOpiVja44r4Svw+P5Xw2pNAhl1v0kb/2bsD7G3rr1XZ5qXC WUIwz4jzkFy3YMagtBfxAOyhkH4ufO6n8uQsyQ0chjKIALFUJpNo/TluAtQDYvyl/oqz 1kN0PgFCxGQ9uffuN4FGFF/HaItx/d7egHJ5eYv9ICMcind/2mGIH16OYgnkNK3qzOcI ZE0PmXcH+vm75nF9tJudiuZJ7gFmQclmoev/88e7PA5h5/089oRtA152o6i9PPudIU2F V5Q0IOad7+f9ueIJoTGMz5i1Wwmts6NGSBJDtbGbXv3T+fqENWnKQ1lHj5Ov34gyhWNA kF1w== X-Received: by 10.180.77.199 with SMTP id u7mr58774271wiw.42.1427475136449; Fri, 27 Mar 2015 09:52:16 -0700 (PDT) Received: from nuc.home.com (80-110-94-70.cgn.dynamic.surfer.at. [80.110.94.70]) by mx.google.com with ESMTPSA id j7sm3592306wix.4.2015.03.27.09.52.14 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 27 Mar 2015 09:52:15 -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 Cc: Andreas Gruenbacher Subject: [RFC 27/39] richacl: Apply the file masks to a richacl Date: Fri, 27 Mar 2015 17:50:25 +0100 Message-Id: <4171fb47be860b3315f7760da9c914422c85acba.1427471526.git.agruenba@redhat.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: References: In-Reply-To: References: Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@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 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 | 101 ++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/richacl.h | 3 ++ 2 files changed, 104 insertions(+) diff --git a/fs/richacl_compat.c b/fs/richacl_compat.c index 4f76cb9..981bd49 100644 --- a/fs/richacl_compat.c +++ b/fs/richacl_compat.c @@ -646,3 +646,104 @@ richacl_isolate_group_class(struct richacl_alloc *x) } return 0; } + +/** + * __richacl_apply_masks - apply the file masks to all aces + * @x: 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 *x) +{ + struct richace *ace; + + richacl_for_each_entry(ace, x->acl) { + unsigned int mask; + + if (richace_is_inherit_only(ace) || !richace_is_allow(ace)) + continue; + if (richace_is_owner(ace)) + mask = x->acl->a_owner_mask; + else if (richace_is_everyone(ace)) + mask = x->acl->a_other_mask; + else + mask = x->acl->a_group_mask; + if (richace_change_mask(x, &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 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) +{ + int retval = 0; + + if ((*acl)->a_flags & RICHACL_MASKED) { + struct richacl_alloc x = { + .acl = *acl, + .count = (*acl)->a_count, + }; + + if (richacl_move_everyone_aces_down(&x) || + richacl_propagate_everyone(&x) || + __richacl_apply_masks(&x) || + richacl_isolate_owner_class(&x) || + richacl_isolate_group_class(&x)) + retval = -ENOMEM; + + x.acl->a_flags &= ~RICHACL_MASKED; + *acl = x.acl; + } + + return retval; +} +EXPORT_SYMBOL_GPL(richacl_apply_masks); diff --git a/include/linux/richacl.h b/include/linux/richacl.h index c709345..1a07ea0 100644 --- a/include/linux/richacl.h +++ b/include/linux/richacl.h @@ -323,4 +323,7 @@ extern int richacl_equiv_mode(const struct richacl *, mode_t *); 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 **); + #endif /* __RICHACL_H */