Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760157AbXINA1j (ORCPT ); Thu, 13 Sep 2007 20:27:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753506AbXINA1a (ORCPT ); Thu, 13 Sep 2007 20:27:30 -0400 Received: from mail9.hitachi.co.jp ([133.145.228.44]:48799 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752475AbXINA13 (ORCPT ); Thu, 13 Sep 2007 20:27:29 -0400 Date: Fri, 14 Sep 2007 09:27:07 +0900 From: Yuichi Nakamura To: selinux@tycho.nsa.gov Subject: [PATCH] selinux: Improving SELinux read/write performance Cc: ynakam@hitachisoft.jp, Stephen Smalley , James Morris , Eric Paris , kaigai@ak.jp.nec.com, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Message-Id: <20070914092048.C8F1.YNAKAM@hitachisoft.jp> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.31 [ja] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 11539 Lines: 303 Hello. I would like to propose patch that reduces overhead in read/write by SELinux. I sent RFC in previous thread. http://lkml.org/lkml/2007/9/6/14 As a result of discussion in previous thread, quality of code has improved, so I would like to submit patch here. 1. Background Look at benchmark result below. lmbench simple read/write(average of 5 run). Big overhead exists especially on SH(SuperH) arch. 1) Result for x86(Pentium 4 2.6Ghz), kernel 2.6.22 Base SELinux Overhead(%) Simple read 1.10 1.24 12.3 Simple write 1.02 1.14 14.0 * Base: kernel compiled without SELinux support 2) Result for SH(SH4, SH7751R), kernel 2.6.22 Base SELinux Overhead(%) Simple read 2.39 5.49 130.5 Simple write 2.07 5.10 146.6 2. About patch It reduces the selinux overhead on read/write by only revalidating permissions in selinux_file_permission if the task or inode labels have changed or the policy has changed since the open-time check. A new LSM hook, security_dentry_open, is added to capture the necessary state at open time to allow this optimization. 3. Result of benchmark after applying patch 1) Result for x86(Pentium 4 2.6Ghz), kernel 2.6.22 Base SELinux Overhead(%) Simple read 1.10 1.13 2.3(Before 12.3) Simple write 1.02 1.024 0.6(Before 14.0) * Base: kernel compiled without SELinux support 2) Result for SH(SH4, SH7751R), kernel 2.6.22 Base SELinux Overhead(%) Simple read 2.39 2.63 10.4(Before 130.5) Simple write 2.07 2.34 13.1(Before 146.6) Overhead in read/write is reduced a lot. This patch adds permission check at open time(in __dentry_open), but open/close performance does not get worse as shown below. * Lmbench simple open/close Pentium 4(before patch): Base SELinux Overhead(%) open/close 5.97 7.45 24.9 after patch: open/close 5.97 7.48 25.3 SH(before patch): Base SELinux Overhead(%) open/close 32.6 62.8 93.0 after patch: open/close 32.6 58.7 80.2 Next is a patch for 2.6.22. It reduces the selinux overhead on read/write by only revalidating permissions in selinux_file_permission if the task or inode labels have changed or the policy has changed since the open-time check. A new LSM hook, security_dentry_open, is added to capture the necessary state at open time to allow this optimization. Signed-off-by: Yuichi Nakamura --- fs/open.c | 4 ++ include/linux/security.h | 18 ++++++++++++ security/dummy.c | 6 ++++ security/selinux/avc.c | 5 +++ security/selinux/hooks.c | 53 +++++++++++++++++++++++++++++++++++++- security/selinux/include/avc.h | 2 + security/selinux/include/objsec.h | 2 + 7 files changed, 89 insertions(+), 1 deletion(-) diff -purN -X linux-2.6.22/Documentation/dontdiff linux-2.6.22.orig/security/selinux/avc.c linux-2.6.22/security/selinux/avc.c --- linux-2.6.22.orig/security/selinux/avc.c 2007-07-09 08:32:17.000000000 +0900 +++ linux-2.6.22/security/selinux/avc.c 2007-09-14 08:35:04.000000000 +0900 @@ -913,3 +913,8 @@ int avc_has_perm(u32 ssid, u32 tsid, u16 avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata); return rc; } + +u32 avc_policy_seqno(void) +{ + return avc_cache.latest_notif; +} diff -purN -X linux-2.6.22/Documentation/dontdiff linux-2.6.22.orig/security/selinux/hooks.c linux-2.6.22/security/selinux/hooks.c --- linux-2.6.22.orig/security/selinux/hooks.c 2007-07-09 08:32:17.000000000 +0900 +++ linux-2.6.22/security/selinux/hooks.c 2007-09-14 08:43:51.000000000 +0900 @@ -14,6 +14,8 @@ * * Copyright (C) 2006 Hewlett-Packard Development Company, L.P. * Paul Moore, + * Copyright (C) 2007 Hitachi Software Engineering Co., Ltd. + * Yuichi Nakamura * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2, @@ -2458,7 +2460,7 @@ static int selinux_inode_listsecurity(st /* file security operations */ -static int selinux_file_permission(struct file *file, int mask) +static int selinux_revalidate_file_permission(struct file *file, int mask) { int rc; struct inode *inode = file->f_path.dentry->d_inode; @@ -2480,6 +2482,25 @@ static int selinux_file_permission(struc return selinux_netlbl_inode_permission(inode, mask); } +static int selinux_file_permission(struct file *file, int mask) +{ + struct inode *inode = file->f_path.dentry->d_inode; + struct task_security_struct *tsec = current->security; + struct file_security_struct *fsec = file->f_security; + struct inode_security_struct *isec = inode->i_security; + + if (!mask) { + /* No permission to check. Existence test. */ + return 0; + } + + if (tsec->sid == fsec->sid && fsec->isid == isec->sid + && fsec->pseqno == avc_policy_seqno()) + return selinux_netlbl_inode_permission(inode, mask); + + return selinux_revalidate_file_permission(file, mask); +} + static int selinux_file_alloc_security(struct file *file) { return file_alloc_security(file); @@ -2715,6 +2736,34 @@ static int selinux_file_receive(struct f return file_has_perm(current, file, file_to_av(file)); } +static int selinux_dentry_open(struct file *file) +{ + struct file_security_struct *fsec; + struct inode *inode; + struct inode_security_struct *isec; + inode = file->f_path.dentry->d_inode; + fsec = file->f_security; + isec = inode->i_security; + /* + * Save inode label and policy sequence number + * at open-time so that selinux_file_permission + * can determine whether revalidation is necessary. + * Task label is already saved in the file security + * struct as its SID. + */ + fsec->isid = isec->sid; + fsec->pseqno = avc_policy_seqno(); + /* + * Since the inode label or policy seqno may have changed + * between the selinux_inode_permission check and the saving + * of state above, recheck that access is still permitted. + * Otherwise, access might never be revalidated against the + * new inode label or new policy. + * This check is not redundant - do not remove. + */ + return inode_has_perm(current, inode, file_to_av(file), NULL); +} + /* task security operations */ static int selinux_task_create(unsigned long clone_flags) @@ -4780,6 +4829,8 @@ static struct security_operations selinu .file_send_sigiotask = selinux_file_send_sigiotask, .file_receive = selinux_file_receive, + .dentry_open = selinux_dentry_open, + .task_create = selinux_task_create, .task_alloc_security = selinux_task_alloc_security, .task_free_security = selinux_task_free_security, diff -purN -X linux-2.6.22/Documentation/dontdiff linux-2.6.22.orig/security/selinux/include/avc.h linux-2.6.22/security/selinux/include/avc.h --- linux-2.6.22.orig/security/selinux/include/avc.h 2007-07-09 08:32:17.000000000 +0900 +++ linux-2.6.22/security/selinux/include/avc.h 2007-09-14 08:35:04.000000000 +0900 @@ -110,6 +110,8 @@ int avc_has_perm(u32 ssid, u32 tsid, u16 tclass, u32 requested, struct avc_audit_data *auditdata); +u32 avc_policy_seqno(void); + #define AVC_CALLBACK_GRANT 1 #define AVC_CALLBACK_TRY_REVOKE 2 #define AVC_CALLBACK_REVOKE 4 diff -purN -X linux-2.6.22/Documentation/dontdiff linux-2.6.22.orig/security/selinux/include/objsec.h linux-2.6.22/security/selinux/include/objsec.h --- linux-2.6.22.orig/security/selinux/include/objsec.h 2007-07-09 08:32:17.000000000 +0900 +++ linux-2.6.22/security/selinux/include/objsec.h 2007-09-14 08:35:04.000000000 +0900 @@ -53,6 +53,8 @@ struct file_security_struct { struct file *file; /* back pointer to file object */ u32 sid; /* SID of open file description */ u32 fown_sid; /* SID of file owner (for SIGIO) */ + u32 isid; /* SID of inode at the time of file open */ + u32 pseqno; /* Policy seqno at the time of file open */ }; struct superblock_security_struct { diff -purN -X linux-2.6.22/Documentation/dontdiff linux-2.6.22.orig/fs/open.c linux-2.6.22/fs/open.c --- linux-2.6.22.orig/fs/open.c 2007-07-09 08:32:17.000000000 +0900 +++ linux-2.6.22/fs/open.c 2007-09-14 08:40:46.000000000 +0900 @@ -696,6 +696,10 @@ static struct file *__dentry_open(struct f->f_op = fops_get(inode->i_fop); file_move(f, &inode->i_sb->s_files); + error = security_dentry_open(f); + if (error) + goto cleanup_all; + if (!open && f->f_op) open = f->f_op->open; if (open) { diff -purN -X linux-2.6.22/Documentation/dontdiff linux-2.6.22.orig/include/linux/security.h linux-2.6.22/include/linux/security.h --- linux-2.6.22.orig/include/linux/security.h 2007-07-09 08:32:17.000000000 +0900 +++ linux-2.6.22/include/linux/security.h 2007-09-14 08:44:13.000000000 +0900 @@ -503,6 +503,13 @@ struct request_sock; * @file contains the file structure being received. * Return 0 if permission is granted. * + * Security hook for dentry + * + * @dentry_open + * Save open-time permission checking state for later use upon + * file_permission, and recheck access if anything has changed + * since inode_permission. + * * Security hooks for task operations. * * @task_create: @@ -1253,6 +1260,7 @@ struct security_operations { int (*file_send_sigiotask) (struct task_struct * tsk, struct fown_struct * fown, int sig); int (*file_receive) (struct file * file); + int (*dentry_open) (struct file *file); int (*task_create) (unsigned long clone_flags); int (*task_alloc_security) (struct task_struct * p); @@ -1854,6 +1862,11 @@ static inline int security_file_receive return security_ops->file_receive (file); } +static inline int security_dentry_open (struct file *file) +{ + return security_ops->dentry_open (file); +} + static inline int security_task_create (unsigned long clone_flags) { return security_ops->task_create (clone_flags); @@ -2529,6 +2542,11 @@ static inline int security_file_receive return 0; } +static inline int security_dentry_open (struct file *file) +{ + return 0; +} + static inline int security_task_create (unsigned long clone_flags) { return 0; --- linux-2.6.22.orig/security/dummy.c 2007-07-09 08:32:17.000000000 +0900 +++ linux-2.6.22/security/dummy.c 2007-09-14 08:35:04.000000000 +0900 @@ -459,6 +459,11 @@ static int dummy_file_receive (struct fi return 0; } +static int dummy_dentry_open (struct file *file) +{ + return 0; +} + static int dummy_task_create (unsigned long clone_flags) { return 0; @@ -1029,6 +1034,7 @@ void security_fixup_ops (struct security set_to_dummy_if_null(ops, file_set_fowner); set_to_dummy_if_null(ops, file_send_sigiotask); set_to_dummy_if_null(ops, file_receive); + set_to_dummy_if_null(ops, dentry_open); set_to_dummy_if_null(ops, task_create); set_to_dummy_if_null(ops, task_alloc_security); set_to_dummy_if_null(ops, task_free_security); Regards, -- Yuichi Nakamura Hitachi Software Engineering Co., Ltd. Japan SELinux Users Group(JSELUG): http://www.selinux.gr.jp/ SELinux Policy Editor: http://seedit.sourceforge.net/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/