From patchwork Tue Aug 4 11:53:08 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: 6937981 Return-Path: X-Original-To: patchwork-cifs-client@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 0F2F89F373 for ; Tue, 4 Aug 2015 12:09:25 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 02A1920395 for ; Tue, 4 Aug 2015 12:09:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DBB5E203E1 for ; Tue, 4 Aug 2015 12:09:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933612AbbHDLyy (ORCPT ); Tue, 4 Aug 2015 07:54:54 -0400 Received: from mail-wi0-f178.google.com ([209.85.212.178]:35454 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933577AbbHDLyu (ORCPT ); Tue, 4 Aug 2015 07:54:50 -0400 Received: by wibxm9 with SMTP id xm9so162748891wib.0; Tue, 04 Aug 2015 04:54:48 -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=s2gB9j7jwkcjpzMrsxU18WDq8fxSQwoZ/IAARsxpBIk=; b=MgLlWDtyciyId7E5tbGpHuc6gRq/nQcgyOOROyvBdGGM4mvpv5zV1xnLBGpNm41QQZ 7dc1OvHgfTcFhgLlXSLa9TI1tED0jw+65x9p5mBXcvsJf0vL6P7eo5+TE/fli0qzAWzz M6OxOE2qUCBkGqtcPjPtGlQjzk1JUGRNOdzn5n6EyWNYqI+wdxBDdcK9oGVfA6NhZPRB dYA9XlGpPG8/D0UGElx7ArE80rGI0iSAp0vsD8wtuV2ov9OL7YjrP2Bam4kIskYnDg00 7bTZgDMT7HBr741tLJ4pcQWVe6tCx9f3Ox9Ukw4qF6RCmi/15vFX0htD8VkGOMUZCTEg ea1g== X-Received: by 10.180.218.195 with SMTP id pi3mr7022031wic.71.1438689287867; Tue, 04 Aug 2015 04:54:47 -0700 (PDT) Received: from schleppi.home.com (p54980F84.dip0.t-ipconnect.de. [84.152.15.132]) by smtp.gmail.com with ESMTPSA id u7sm2018458wif.3.2015.08.04.04.54.45 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 04 Aug 2015 04:54:47 -0700 (PDT) From: Andreas Gruenbacher X-Google-Original-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, linux-cifs@vger.kernel.org, linux-security-module@vger.kernel.org, Andreas Gruenbacher Subject: [RFC v6 10/40] richacl: Permission check algorithm Date: Tue, 4 Aug 2015 13:53:08 +0200 Message-Id: <1438689218-6921-11-git-send-email-agruenba@redhat.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1438689218-6921-1-git-send-email-agruenba@redhat.com> References: <1438689218-6921-1-git-send-email-agruenba@redhat.com> Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, SUSPICIOUS_RECIPS, 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 A richacl roughly grants a requested access if the NFSv4 acl in the richacl grants the requested permissions according to the NFSv4 permission check algorithm and the file mask that applies to the process includes the requested permissions. Signed-off-by: Andreas Gruenbacher --- fs/Makefile | 2 +- fs/richacl_inode.c | 146 ++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/richacl.h | 3 + 3 files changed, 150 insertions(+), 1 deletion(-) create mode 100644 fs/richacl_inode.c diff --git a/fs/Makefile b/fs/Makefile index ddc43d8..1305047 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -48,7 +48,7 @@ obj-$(CONFIG_SYSCTL) += drop_caches.o obj-$(CONFIG_FHANDLE) += fhandle.o obj-$(CONFIG_FS_RICHACL) += richacl.o -richacl-y := richacl_base.o +richacl-y := richacl_base.o richacl_inode.o obj-y += quota/ diff --git a/fs/richacl_inode.c b/fs/richacl_inode.c new file mode 100644 index 0000000..6d94e064 --- /dev/null +++ b/fs/richacl_inode.c @@ -0,0 +1,146 @@ +/* + * Copyright (C) 2010 Novell, Inc. + * Copyright (C) 2015 Red Hat, Inc. + * Written by Andreas Gruenbacher + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2, or (at your option) any + * later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ + +#include +#include +#include +#include +#include + +/** + * richacl_permission - richacl permission check algorithm + * @inode: inode to check + * @acl: rich acl of the inode + * @want: requested access (MAY_* flags) + * + * Checks if the current process is granted @mask flags in @acl. + */ +int +richacl_permission(struct inode *inode, const struct richacl *acl, + int want) +{ + const struct richace *ace; + unsigned int mask = richacl_want_to_mask(want); + unsigned int requested = mask, denied = 0; + int in_owning_group = in_group_p(inode->i_gid); + int in_owner_or_group_class = in_owning_group; + + /* + * A process is + * - in the owner file class if it owns the file, + * - in the group file class if it is in the file's owning group or + * it matches any of the user or group entries, and + * - in the other file class otherwise. + * The file class is only relevant for determining which file mask to + * apply, which only happens for masked acls. + */ + if (acl->a_flags & RICHACL_MASKED) { + if ((acl->a_flags & RICHACL_WRITE_THROUGH) && + uid_eq(current_fsuid(), inode->i_uid)) { + denied = requested & ~acl->a_owner_mask; + goto out; + } + } else { + /* + * We don't care which class the process is in when the acl is + * not masked. + */ + in_owner_or_group_class = 1; + } + + /* + * Check if the acl grants the requested access and determine which + * file class the process is in. + */ + richacl_for_each_entry(ace, acl) { + unsigned int ace_mask = ace->e_mask; + + if (richace_is_inherit_only(ace)) + continue; + if (richace_is_owner(ace)) { + if (!uid_eq(current_fsuid(), inode->i_uid)) + continue; + goto entry_matches_owner; + } else if (richace_is_group(ace)) { + if (!in_owning_group) + continue; + } else if (richace_is_unix_user(ace)) { + if (!uid_eq(current_fsuid(), ace->e_id.uid)) + continue; + } else if (richace_is_unix_group(ace)) { + if (!in_group_p(ace->e_id.gid)) + continue; + } else + goto entry_matches_everyone; + + /* + * Apply the group file mask to entries other than owner@ and + * everyone@ or user entries matching the owner. This ensures + * that we grant the same permissions as the acl computed by + * richacl_apply_masks(). + * + * Without this restriction, the following richacl would grant + * rw access to processes which are both the owner and in the + * owning group, but not to other users in the owning group, + * which could not be represented without masks: + * + * owner:rw::mask + * group@:rw::allow + */ + if ((acl->a_flags & RICHACL_MASKED) && richace_is_allow(ace)) + ace_mask &= acl->a_group_mask; + +entry_matches_owner: + /* The process is in the owner or group file class. */ + in_owner_or_group_class = 1; + +entry_matches_everyone: + /* Check which mask flags the ACE allows or denies. */ + if (richace_is_deny(ace)) + denied |= ace_mask & mask; + mask &= ~ace_mask; + + /* + * Keep going until we know which file class + * the process is in. + */ + if (!mask && in_owner_or_group_class) + break; + } + denied |= mask; + + if (acl->a_flags & RICHACL_MASKED) { + /* + * The file class a process is in determines which file mask + * applies. Check if that file mask also grants the requested + * access. + */ + if (uid_eq(current_fsuid(), inode->i_uid)) + denied |= requested & ~acl->a_owner_mask; + else if (in_owner_or_group_class) + denied |= requested & ~acl->a_group_mask; + else { + if (acl->a_flags & RICHACL_WRITE_THROUGH) + denied = requested & ~acl->a_other_mask; + else + denied |= requested & ~acl->a_other_mask; + } + } + +out: + return denied ? -EACCES : 0; +} +EXPORT_SYMBOL_GPL(richacl_permission); diff --git a/include/linux/richacl.h b/include/linux/richacl.h index 8df6d93..756b711 100644 --- a/include/linux/richacl.h +++ b/include/linux/richacl.h @@ -306,4 +306,7 @@ 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); +/* richacl_inode.c */ +extern int richacl_permission(struct inode *, const struct richacl *, int); + #endif /* __RICHACL_H */