From patchwork Wed Jun 24 21:57:09 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: 6670361 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 A3E5EC05AC for ; Wed, 24 Jun 2015 21:59:14 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 7F4C42052F for ; Wed, 24 Jun 2015 21:59:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5146220575 for ; Wed, 24 Jun 2015 21:59:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752950AbbFXV7F (ORCPT ); Wed, 24 Jun 2015 17:59:05 -0400 Received: from mail-wg0-f48.google.com ([74.125.82.48]:33100 "EHLO mail-wg0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752428AbbFXV6D (ORCPT ); Wed, 24 Jun 2015 17:58:03 -0400 Received: by wgck11 with SMTP id k11so47335832wgc.0; Wed, 24 Jun 2015 14:58:00 -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=3drS6qtDldYkJBqDKUUmK+IH3LVenbc+8I3b/MRIQKg=; b=aihsSDdz4V9mREUXVozg6+QR/H8SenGTcdOOR8mmcpKqXItdgwQpZs/YBUgLjsYE4Y EgmvmKLNjK1gH1trs5M11y/F/XGMU2F5Nppd6m0YpWzRTatiaKoZKuCtaB4xX8/w335B YEORVBDKgShKZg8z+oleuit6Z7XEi5R3JS4xe1+LTw5Fmou0fTbWB27UQl+26JqJ3QVv EbrsGYq1HRNCrWrHE+qrA45C5Yjyu1S9xzwHxaTsYkiu6aJ++Emi4Yjf6rPUwWvKFD7s yEkUHDOUOrgRl0C9/nNhfGVobKnErI8d28dk2hjkkKQry8wzmo+5eGiJPcIZvvz+37Rl sKlw== X-Received: by 10.194.76.237 with SMTP id n13mr11931608wjw.111.1435183080878; Wed, 24 Jun 2015 14:58:00 -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.9.2015.06.24.14.57.59 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 24 Jun 2015 14:58:00 -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 20/31] richacl: acl editing helper functions Date: Wed, 24 Jun 2015 23:57:09 +0200 Message-Id: <1435183040-22726-21-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 The file masks in richacls make chmod and creating new files more efficient than having to apply file permission bits to the acl directly. They also allow us to regain permissions from an acl even after a restrictive chmod, because the permissions in the acl itself are not being destroyed. In POSIX ACLs, the mask entry has a similar function. Protocols like nfsv4 do not understand file masks. For those protocols, we need to compute nfs4 acls which represent the effective permissions granted by a richacl: we need to "apply" the file masks to the acl. This is the first in a series of richacl transformation patches; it implements basic richacl editing functions. The following patches implement algorithms for transforming a richacl so that it can be evaluated as a plain nfs4 acl, with identical permission check results. Signed-off-by: Andreas Gruenbacher --- fs/Makefile | 3 +- fs/richacl_compat.c | 161 +++++++++++++++++++++++++++++++++++++++++ include/linux/richacl_compat.h | 40 ++++++++++ 3 files changed, 203 insertions(+), 1 deletion(-) create mode 100644 fs/richacl_compat.c create mode 100644 include/linux/richacl_compat.h diff --git a/fs/Makefile b/fs/Makefile index e0cdaab..1baae4e 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -48,7 +48,8 @@ obj-$(CONFIG_SYSCTL) += drop_caches.o obj-$(CONFIG_FHANDLE) += fhandle.o obj-$(CONFIG_FS_RICHACL) += richacl.o -richacl-y := richacl_base.o richacl_inode.o richacl_xattr.o +richacl-y := richacl_base.o richacl_inode.o \ + richacl_xattr.o richacl_compat.o obj-y += quota/ diff --git a/fs/richacl_compat.c b/fs/richacl_compat.c new file mode 100644 index 0000000..1c62c3c --- /dev/null +++ b/fs/richacl_compat.c @@ -0,0 +1,161 @@ +/* + * Copyright (C) 2006, 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 + +/** + * richacl_prepare - allocate richacl being constructed + * + * Allocate a richacl which can hold @count entries but which is initially + * empty. + */ +struct richacl *richacl_prepare(struct richacl_alloc *alloc, unsigned int count) +{ + alloc->acl = richacl_alloc(count, GFP_KERNEL); + if (!alloc->acl) + return NULL; + alloc->acl->a_count = 0; + alloc->count = count; + return alloc->acl; +} +EXPORT_SYMBOL_GPL(richacl_prepare); + +/** + * richacl_delete_entry - delete an entry in an acl + * @alloc: acl and number of allocated entries + * @ace: an entry in @alloc->acl + * + * Updates @ace so that it points to the entry before the deleted entry + * on return. (When deleting the first entry, @ace will point to the + * (non-existant) entry before the first entry). This behavior is the + * expected behavior when deleting entries while forward iterating over + * an acl. + */ +void +richacl_delete_entry(struct richacl_alloc *alloc, struct richace **ace) +{ + void *end = alloc->acl->a_entries + alloc->acl->a_count; + + memmove(*ace, *ace + 1, end - (void *)(*ace + 1)); + (*ace)--; + alloc->acl->a_count--; +} +EXPORT_SYMBOL_GPL(richacl_delete_entry); + +/** + * richacl_insert_entry - insert an entry in an acl + * @alloc: acl and number of allocated entries + * @ace: entry before which the new entry shall be inserted + * + * Insert a new entry in @alloc->acl at position @ace and zero-initialize + * it. This may require reallocating @alloc->acl. + */ +int +richacl_insert_entry(struct richacl_alloc *alloc, struct richace **ace) +{ + if (alloc->count == alloc->acl->a_count) { + int n = *ace - alloc->acl->a_entries; + struct richacl *acl2; + + acl2 = richacl_alloc(alloc->acl->a_count + 1, GFP_KERNEL); + if (!acl2) + return -1; + acl2->a_flags = alloc->acl->a_flags; + acl2->a_owner_mask = alloc->acl->a_owner_mask; + acl2->a_group_mask = alloc->acl->a_group_mask; + acl2->a_other_mask = alloc->acl->a_other_mask; + memcpy(acl2->a_entries, alloc->acl->a_entries, + n * sizeof(struct richace)); + memcpy(acl2->a_entries + n + 1, *ace, + (alloc->acl->a_count - n) * sizeof(struct richace)); + kfree(alloc->acl); + alloc->acl = acl2; + alloc->count = acl2->a_count; + *ace = acl2->a_entries + n; + } else { + void *end = alloc->acl->a_entries + alloc->acl->a_count; + + memmove(*ace + 1, *ace, end - (void *)*ace); + alloc->acl->a_count++; + } + memset(*ace, 0, sizeof(struct richace)); + return 0; +} +EXPORT_SYMBOL_GPL(richacl_insert_entry); + +/** + * richacl_append_entry - append an entry to an acl + * @alloc: acl and number of allocated entries + * + * This may require reallocating @alloc->acl. + */ +struct richace *richacl_append_entry(struct richacl_alloc *alloc) +{ + struct richacl *acl = alloc->acl; + struct richace *ace = acl->a_entries + acl->a_count; + + if (alloc->count > alloc->acl->a_count) { + acl->a_count++; + return ace; + } + return richacl_insert_entry(alloc, &ace) ? NULL : ace; +} +EXPORT_SYMBOL_GPL(richacl_append_entry); + +/** + * richace_change_mask - set the mask of @ace to @mask + * @alloc: acl and number of allocated entries + * @ace: entry to modify + * @mask: new mask for @ace + * + * If @ace is inheritable, a inherit-only ace is inserted before @ace which + * includes the inheritable permissions of @ace and the inheritance flags of + * @ace are cleared before changing the mask. + * + * If @mask is 0, the original ace is turned into an inherit-only entry if + * there are any inheritable permissions, and removed otherwise. + * + * The returned @ace points to the modified or inserted effective-only acl + * entry if that entry exists, to the entry that has become inheritable-only, + * or else to the previous entry in the acl. + */ +static int +richace_change_mask(struct richacl_alloc *alloc, struct richace **ace, + unsigned int mask) +{ + if (mask && (*ace)->e_mask == mask) + (*ace)->e_flags &= ~RICHACE_INHERIT_ONLY_ACE; + else if (mask & ~RICHACE_POSIX_ALWAYS_ALLOWED) { + if (richace_is_inheritable(*ace)) { + if (richacl_insert_entry(alloc, ace)) + return -1; + memcpy(*ace, *ace + 1, sizeof(struct richace)); + (*ace)->e_flags |= RICHACE_INHERIT_ONLY_ACE; + (*ace)++; + richace_clear_inheritance_flags(*ace); + } + (*ace)->e_mask = mask; + } else { + if (richace_is_inheritable(*ace)) + (*ace)->e_flags |= RICHACE_INHERIT_ONLY_ACE; + else + richacl_delete_entry(alloc, ace); + } + return 0; +} diff --git a/include/linux/richacl_compat.h b/include/linux/richacl_compat.h new file mode 100644 index 0000000..a9ff630 --- /dev/null +++ b/include/linux/richacl_compat.h @@ -0,0 +1,40 @@ +/* + * 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. + */ + +#ifndef __RICHACL_COMPAT_H +#define __RICHACL_COMPAT_H + +#include + +/** + * struct richacl_alloc - remember how many entries are actually allocated + * @acl: acl with a_count <= @count + * @count: the actual number of entries allocated in @acl + * + * We pass around this structure while modifying an acl so that we do + * not have to reallocate when we remove existing entries followed by + * adding new entries. + */ +struct richacl_alloc { + struct richacl *acl; + unsigned int count; +}; + +struct richacl *richacl_prepare(struct richacl_alloc *, unsigned int); +struct richace *richacl_append_entry(struct richacl_alloc *); +int richacl_insert_entry(struct richacl_alloc *, struct richace **); +void richacl_delete_entry(struct richacl_alloc *, struct richace **); + +#endif /* __RICHACL_COMPAT_H */