audit: convert sessionid unset to a macro

Use a macro, "AUDIT_SID_UNSET", to replace each instance of
initialization and comparison to an audit session ID.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

include/linux/audit.h

@@ -510,7 +510,7 @@ static inline kuid_t audit_get_loginuid(struct task_struct *tsk)
 }
 static inline unsigned int audit_get_sessionid(struct task_struct *tsk)
 {
-	return -1;
+	return AUDIT_SID_UNSET;
 }
 static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp)
 { }

include/net/xfrm.h

@@ -751,7 +751,7 @@ static inline void xfrm_audit_helper_usrinfo(bool task_valid,
 					    audit_get_loginuid(current) :
 					    INVALID_UID);
 	const unsigned int ses = task_valid ? audit_get_sessionid(current) :
-		(unsigned int) -1;
+		AUDIT_SID_UNSET;
 
 	audit_log_format(audit_buf, " auid=%u ses=%u", auid, ses);
 	audit_log_task_context(audit_buf);

include/uapi/linux/audit.h

@@ -465,6 +465,7 @@ struct audit_tty_status {
 };
 
 #define AUDIT_UID_UNSET (unsigned int)-1
+#define AUDIT_SID_UNSET ((unsigned int)-1)
 
 /* audit_rule_data supports filter rules with both integer and string
  * fields.  It corresponds with AUDIT_ADD_RULE, AUDIT_DEL_RULE and

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>
@@ -119,7 +120,7 @@ struct task_struct init_task
 	.thread_node	= LIST_HEAD_INIT(init_signals.thread_head),
 #ifdef CONFIG_AUDITSYSCALL
 	.loginuid	= INVALID_UID,
-	.sessionid	= (unsigned int)-1,
+	.sessionid	= AUDIT_SID_UNSET,
 #endif
 #ifdef CONFIG_PERF_EVENTS
 	.perf_event_mutex = __MUTEX_INITIALIZER(init_task.perf_event_mutex),

kernel/auditsc.c

@@ -2050,7 +2050,7 @@ static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid,
 int audit_set_loginuid(kuid_t loginuid)
 {
 	struct task_struct *task = current;
-	unsigned int oldsessionid, sessionid = (unsigned int)-1;
+	unsigned int oldsessionid, sessionid = AUDIT_SID_UNSET;
 	kuid_t oldloginuid;
 	int rc;
 
@@ -2064,7 +2064,7 @@ int audit_set_loginuid(kuid_t loginuid)
 	/* are we setting or clearing? */
 	if (uid_valid(loginuid)) {
 		sessionid = (unsigned int)atomic_inc_return(&session_id);
-		if (unlikely(sessionid == (unsigned int)-1))
+		if (unlikely(sessionid == AUDIT_SID_UNSET))
 			sessionid = (unsigned int)atomic_inc_return(&session_id);
 	}