From patchwork Mon Sep 5 17:25:37 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Aneesh Kumar K.V" X-Patchwork-Id: 1125202 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter1.kernel.org (8.14.4/8.14.4) with ESMTP id p85HUhQ7011560 for ; Mon, 5 Sep 2011 17:30:43 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752796Ab1IERaO (ORCPT ); Mon, 5 Sep 2011 13:30:14 -0400 Received: from e28smtp01.in.ibm.com ([122.248.162.1]:60666 "EHLO e28smtp01.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751870Ab1IER13 (ORCPT ); Mon, 5 Sep 2011 13:27:29 -0400 Received: from d28relay03.in.ibm.com (d28relay03.in.ibm.com [9.184.220.60]) by e28smtp01.in.ibm.com (8.14.4/8.13.1) with ESMTP id p85HRPZM026251; Mon, 5 Sep 2011 22:57:25 +0530 Received: from d28av03.in.ibm.com (d28av03.in.ibm.com [9.184.220.65]) by d28relay03.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p85HRPu54485274; Mon, 5 Sep 2011 22:57:25 +0530 Received: from d28av03.in.ibm.com (loopback [127.0.0.1]) by d28av03.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p85HRORg021669; Tue, 6 Sep 2011 03:27:25 +1000 Received: from skywalker.ibm.com ([9.126.239.225]) by d28av03.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id p85HR6rW021311; Tue, 6 Sep 2011 03:27:23 +1000 From: "Aneesh Kumar K.V" To: agruen@kernel.org, bfields@fieldses.org, akpm@linux-foundation.org, dhowells@redhat.com Cc: aneesh.kumar@linux.vnet.ibm.com, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH -V6 15/26] richacl: Compute maximum file masks from an acl Date: Mon, 5 Sep 2011 22:55:37 +0530 Message-Id: <1315243548-18664-16-git-send-email-aneesh.kumar@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1315243548-18664-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> References: <1315243548-18664-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter1.kernel.org [140.211.167.41]); Mon, 05 Sep 2011 17:30:43 +0000 (UTC) From: Andreas Gruenbacher Compute upper bound owner, group, and other file masks with as few permissions as possible without denying any permissions that the NFSv4 acl in a richacl grants. This algorithm is used when a file inherits an acl at create time and when an acl is set via a mechanism that does not specify file modes (such as via nfsd). When user-space sets an acl, the file masks are passed in as part of the xattr. When setting a richacl, the file masks determine what the file permission bits will be set to; see richacl_masks_to_mode(). Signed-off-by: Andreas Gruenbacher Signed-off-by: Aneesh Kumar K.V --- fs/richacl_base.c | 128 +++++++++++++++++++++++++++++++++++++++++++++++ include/linux/richacl.h | 1 + 2 files changed, 129 insertions(+), 0 deletions(-) diff --git a/fs/richacl_base.c b/fs/richacl_base.c index d55b436..84a5698 100644 --- a/fs/richacl_base.c +++ b/fs/richacl_base.c @@ -225,3 +225,131 @@ richace_set_who(struct richace *ace, const char *who) return 0; } EXPORT_SYMBOL_GPL(richace_set_who); + +/** + * richacl_allowed_to_who - mask flags allowed to a specific who value + * + * Computes the mask values allowed to a specific who value, taking + * EVERYONE@ entries into account. + */ +static unsigned int richacl_allowed_to_who(struct richacl *acl, + struct richace *who) +{ + struct richace *ace; + unsigned int allowed = 0; + + richacl_for_each_entry_reverse(ace, acl) { + if (richace_is_inherit_only(ace)) + continue; + if (richace_is_same_identifier(ace, who) || + richace_is_everyone(ace)) { + if (richace_is_allow(ace)) + allowed |= ace->e_mask; + else if (richace_is_deny(ace)) + allowed &= ~ace->e_mask; + } + } + return allowed; +} + +/** + * richacl_group_class_allowed - maximum permissions the group class is allowed + * + * See richacl_compute_max_masks(). + */ +static unsigned int richacl_group_class_allowed(struct richacl *acl) +{ + struct richace *ace; + unsigned int everyone_allowed = 0, group_class_allowed = 0; + int had_group_ace = 0; + + richacl_for_each_entry_reverse(ace, acl) { + if (richace_is_inherit_only(ace) || + richace_is_owner(ace)) + continue; + + if (richace_is_everyone(ace)) { + if (richace_is_allow(ace)) + everyone_allowed |= ace->e_mask; + else if (richace_is_deny(ace)) + everyone_allowed &= ~ace->e_mask; + } else { + group_class_allowed |= + richacl_allowed_to_who(acl, ace); + + if (richace_is_group(ace)) + had_group_ace = 1; + } + } + if (!had_group_ace) + group_class_allowed |= everyone_allowed; + return group_class_allowed; +} + +/** + * richacl_compute_max_masks - compute upper bound masks + * + * Computes upper bound owner, group, and other masks so that none of + * the mask flags allowed by the acl are disabled (for any choice of the + * file owner or group membership). + */ +void richacl_compute_max_masks(struct richacl *acl) +{ + unsigned int gmask = ~0; + struct richace *ace; + + /* + * @gmask contains all permissions which the group class is ever + * allowed. We use it to avoid adding permissions to the group mask + * from everyone@ allow aces which the group class is always denied + * through other aces. For example, the following acl would otherwise + * result in a group mask or rw: + * + * group@:w::deny + * everyone@:rw::allow + * + * Avoid computing @gmask for acls which do not include any group class + * deny aces: in such acls, the group class is never denied any + * permissions from everyone@ allow aces. + */ + +restart: + acl->a_owner_mask = 0; + acl->a_group_mask = 0; + acl->a_other_mask = 0; + + richacl_for_each_entry_reverse(ace, acl) { + if (richace_is_inherit_only(ace)) + continue; + + if (richace_is_owner(ace)) { + if (richace_is_allow(ace)) + acl->a_owner_mask |= ace->e_mask; + else if (richace_is_deny(ace)) + acl->a_owner_mask &= ~ace->e_mask; + } else if (richace_is_everyone(ace)) { + if (richace_is_allow(ace)) { + acl->a_owner_mask |= ace->e_mask; + acl->a_group_mask |= ace->e_mask & gmask; + acl->a_other_mask |= ace->e_mask; + } else if (richace_is_deny(ace)) { + acl->a_owner_mask &= ~ace->e_mask; + acl->a_group_mask &= ~ace->e_mask; + acl->a_other_mask &= ~ace->e_mask; + } + } else { + if (richace_is_allow(ace)) { + acl->a_owner_mask |= ace->e_mask & gmask; + acl->a_group_mask |= ace->e_mask & gmask; + } else if (richace_is_deny(ace) && gmask == ~0) { + gmask = richacl_group_class_allowed(acl); + if (likely(gmask != ~0)) + /* should always be true */ + goto restart; + } + } + } + + acl->a_flags &= ~ACL4_MASKED; +} +EXPORT_SYMBOL_GPL(richacl_compute_max_masks); diff --git a/include/linux/richacl.h b/include/linux/richacl.h index 7433ba3..102a58c 100644 --- a/include/linux/richacl.h +++ b/include/linux/richacl.h @@ -287,5 +287,6 @@ extern int richace_set_who(struct richace *, const char *); extern int richacl_masks_to_mode(const struct richacl *); extern unsigned int richacl_mode_to_mask(mode_t); extern unsigned int richacl_want_to_mask(int); +extern void richacl_compute_max_masks(struct richacl *); #endif /* __RICHACL_H */