From patchwork Wed Feb 23 13:52:03 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: 584731 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter1.kernel.org (8.14.4/8.14.3) with ESMTP id p1NDvrt3026988 for ; Wed, 23 Feb 2011 13:57:53 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755608Ab1BWNyM (ORCPT ); Wed, 23 Feb 2011 08:54:12 -0500 Received: from e28smtp04.in.ibm.com ([122.248.162.4]:35217 "EHLO e28smtp04.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932188Ab1BWNyI (ORCPT ); Wed, 23 Feb 2011 08:54:08 -0500 Received: from d28relay05.in.ibm.com (d28relay05.in.ibm.com [9.184.220.62]) by e28smtp04.in.ibm.com (8.14.4/8.13.1) with ESMTP id p1NDruo5023548; Wed, 23 Feb 2011 19:23:56 +0530 Received: from d28av05.in.ibm.com (d28av05.in.ibm.com [9.184.220.67]) by d28relay05.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p1NDrkNg671874; Wed, 23 Feb 2011 19:23:49 +0530 Received: from d28av05.in.ibm.com (loopback [127.0.0.1]) by d28av05.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p1NDrj3p020230; Thu, 24 Feb 2011 00:53:46 +1100 Received: from skywalker.ibm.com ([9.77.68.27]) by d28av05.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id p1NDqS29014791; Thu, 24 Feb 2011 00:53:41 +1100 From: "Aneesh Kumar K.V" To: sfrench@us.ibm.com, agruen@linbit.com, dilger.kernel@dilger.ca, sandeen@redhat.com, tytso@mit.edu, bfields@fieldses.org, jlayton@redhat.com Cc: aneesh.kumar@linux.vnet.ibm.com, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, Andreas Gruenbacher Subject: [PATCH -V5 16/24] richacl: Permission check algorithm Date: Wed, 23 Feb 2011 19:22:03 +0530 Message-Id: <1298469131-16555-17-git-send-email-aneesh.kumar@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1298469131-16555-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> References: <1298469131-16555-1-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]); Wed, 23 Feb 2011 13:57:53 +0000 (UTC) diff --git a/fs/richacl_base.c b/fs/richacl_base.c index b59c75c..a6e3199 100644 --- a/fs/richacl_base.c +++ b/fs/richacl_base.c @@ -393,3 +393,102 @@ richacl_chmod(struct richacl *acl, mode_t mode) return clone; } EXPORT_SYMBOL_GPL(richacl_chmod); + +/** + * richacl_permission - richacl permission check algorithm + * @inode: inode to check + * @acl: rich acl of the inode + * @mask: requested access (ACE4_* bitmask) + * + * Checks if the current process is granted @mask flags in @acl. + */ +int +richacl_permission(struct inode *inode, const struct richacl *acl, + unsigned int mask) +{ + const struct richace *ace; + 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; + + /* + * We don't need to know which class the process is in when the acl is + * not masked. + */ + if (!(acl->a_flags & ACL4_MASKED)) + in_owner_or_group_class = 1; + + /* + * 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. + */ + + /* + * 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 (current_fsuid() != inode->i_uid) + continue; + goto is_owner; + } else if (richace_is_group(ace)) { + if (!in_owning_group) + continue; + } else if (richace_is_unix_id(ace)) { + if (ace->e_flags & ACE4_IDENTIFIER_GROUP) { + if (!in_group_p(ace->u.e_id)) + continue; + } else { + if (current_fsuid() != ace->u.e_id) + continue; + } + } else + goto is_everyone; + +is_owner: + /* The process is in the owner or group file class. */ + in_owner_or_group_class = 1; + +is_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 & ACL4_MASKED) { + unsigned int file_mask; + + /* + * The file class a process is in determines which file mask + * applies. Check if that file mask also grants the requested + * access. + */ + if (current_fsuid() == inode->i_uid) + file_mask = acl->a_owner_mask; + else if (in_owner_or_group_class) + file_mask = acl->a_group_mask; + else + file_mask = acl->a_other_mask; + denied |= requested & ~file_mask; + } + + return denied ? -EACCES : 0; +} +EXPORT_SYMBOL_GPL(richacl_permission); diff --git a/include/linux/richacl.h b/include/linux/richacl.h index 3aa165b..c9d2761 100644 --- a/include/linux/richacl.h +++ b/include/linux/richacl.h @@ -289,5 +289,7 @@ 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 *); extern struct richacl *richacl_chmod(struct richacl *, mode_t); +extern int richacl_permission(struct inode *, const struct richacl *, + unsigned int); #endif /* __RICHACL_H */