[PATCH ghak81 RFC V1 5/5] audit: collect audit task parameters

[Richard Guy Briggs]

The audit-related parameters in struct task_struct should ideally be
collected together and accessed through a standard audit API.

Collect the existing loginuid, sessionid and audit_context together in a
new struct audit_task_info pointer called "audit" in struct task_struct.

Use kmem_cache to manage this pool of memory.
Un-inline audit_free() to be able to always recover that memory.

See: https://github.com/linux-audit/audit-kernel/issues/81

Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
---
 MAINTAINERS                |  2 +-
 include/linux/audit.h      |  8 ++++----
 include/linux/audit_task.h | 31 +++++++++++++++++++++++++++++++
 include/linux/sched.h      |  6 ++----
 init/init_task.c           |  8 ++++++--
 kernel/auditsc.c           |  4 ++--
 6 files changed, 46 insertions(+), 13 deletions(-)
 create mode 100644 include/linux/audit_task.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 0a1410d..8c7992d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2510,7 +2510,7 @@ L:	linux-audit@xxxxxxxxxx (moderated for non-subscribers)
 W:	https://github.com/linux-audit
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit.git
 S:	Supported
-F:	include/linux/audit.h
+F:	include/linux/audit*.h
 F:	include/uapi/linux/audit.h
 F:	kernel/audit*
 
diff --git a/include/linux/audit.h b/include/linux/audit.h
index dba0d45..1324969 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -237,11 +237,11 @@ extern void __audit_inode_child(struct inode *parent,
 
 static inline void audit_set_context(struct task_struct *task, struct audit_context *ctx)
 {
-	task->audit_context = ctx;
+	task->audit.ctx = ctx;
 }
 static inline struct audit_context *audit_context(struct task_struct *task)
 {
-	return task->audit_context;
+	return task->audit.ctx;
 }
 static inline bool audit_dummy_context(void)
 {
@@ -330,12 +330,12 @@ extern int auditsc_get_stamp(struct audit_context *ctx,
 
 static inline kuid_t audit_get_loginuid(struct task_struct *tsk)
 {
-	return tsk->loginuid;
+	return tsk->audit.loginuid;
 }
 
 static inline unsigned int audit_get_sessionid(struct task_struct *tsk)
 {
-	return tsk->sessionid;
+	return tsk->audit.sessionid;
 }
 
 extern void __audit_ipc_obj(struct kern_ipc_perm *ipcp);
diff --git a/include/linux/audit_task.h b/include/linux/audit_task.h
new file mode 100644
index 0000000..d4b3a20
--- /dev/null
+++ b/include/linux/audit_task.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* audit_task.h -- definition of audit_task_info structure
+ *
+ * Copyright 2018 Red Hat Inc., Raleigh, North Carolina.
+ * All Rights Reserved.
+ *
+ * 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 of the License, 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.
+ *
+ * Written by Richard Guy Briggs <rgb@xxxxxxxxxx>
+ *
+ */
+
+#ifndef _LINUX_AUDIT_TASK_H_
+#define _LINUX_AUDIT_TASK_H_
+
+struct audit_context;
+struct audit_task_info {
+	kuid_t			loginuid;
+	unsigned int		sessionid;
+	struct audit_context	*ctx;
+};
+
+#endif
diff --git a/include/linux/sched.h b/include/linux/sched.h
index b3d697f..b58eca0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -27,9 +27,9 @@
 #include <linux/signal_types.h>
 #include <linux/mm_types_task.h>
 #include <linux/task_io_accounting.h>
+#include <linux/audit_task.h>
 
 /* task_struct member predeclarations (sorted alphabetically): */
-struct audit_context;
 struct backing_dev_info;
 struct bio_list;
 struct blk_plug;
@@ -832,10 +832,8 @@ struct task_struct {
 
 	struct callback_head		*task_works;
 
-	struct audit_context		*audit_context;
 #ifdef CONFIG_AUDITSYSCALL
-	kuid_t				loginuid;
-	unsigned int			sessionid;
+	struct audit_task_info		audit;
 #endif
 	struct seccomp			seccomp;
 
diff --git a/init/init_task.c b/init/init_task.c
index c788f91..d33260d 100644
--- a/init/init_task.c
+++ b/init/init_task.c
@@ -9,6 +9,7 @@
 #include <linux/init.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
+#include <linux/audit.h>
 
 #include <asm/pgtable.h>
 #include <linux/uaccess.h>
@@ -118,8 +119,11 @@ struct task_struct init_task
 	.thread_group	= LIST_HEAD_INIT(init_task.thread_group),
 	.thread_node	= LIST_HEAD_INIT(init_signals.thread_head),
 #ifdef CONFIG_AUDITSYSCALL
-	.loginuid	= INVALID_UID,
-	.sessionid	= AUDIT_SID_UNSET,
+	.audit		= {
+		.loginuid	= INVALID_UID,
+		.sessionid	= AUDIT_SID_UNSET,
+		.ctx		= NULL,
+	},
 #endif
 #ifdef CONFIG_PERF_EVENTS
 	.perf_event_mutex = __MUTEX_INITIALIZER(init_task.perf_event_mutex),
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index f294e4a..b5d8bff 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2068,8 +2068,8 @@ int audit_set_loginuid(kuid_t loginuid)
 			sessionid = (unsigned int)atomic_inc_return(&session_id);
 	}
 
-	task->sessionid = sessionid;
-	task->loginuid = loginuid;
+	task->audit.sessionid = sessionid;
+	task->audit.loginuid = loginuid;
 out:
 	audit_log_set_loginuid(oldloginuid, loginuid, oldsessionid, sessionid, rc);
 	return rc;
-- 
1.8.3.1