BACKPORT: audit: consistently record PIDs with task_tgid_nr()

Unfortunately we record PIDs in audit records using a variety of
methods despite the correct way being the use of task_tgid_nr().
This patch converts all of these callers, except for the case of
AUDIT_SET in audit_receive_msg() (see the comment in the code).

Reported-by: Jeff Vander Stoep <jeffv@google.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

Bug: 28952093

(cherry picked from commit fa2bea2f5cca5b8d4a3e5520d2e8c0ede67ac108)
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Change-Id: If6645f9de8bc58ed9755f28dc6af5fbf08d72a00

kernel/audit.c

@@ -870,6 +870,12 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 				return err;
 		}
 		if (s.mask & AUDIT_STATUS_PID) {
+			/* NOTE: we are using task_tgid_vnr() below because
+			 *       the s.pid value is relative to the namespace
+			 *       of the caller; at present this doesn't matter
+			 *       much since you can really only run auditd
+			 *       from the initial pid namespace, but something
+			 *       to keep in mind if this changes */
 			int new_pid = s.pid;
 
 			if ((!new_pid) && (task_tgid_vnr(current) != audit_pid))
@@ -1896,7 +1902,7 @@ void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
 			 " euid=%u suid=%u fsuid=%u"
 			 " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
 			 task_ppid_nr(tsk),
-			 task_pid_nr(tsk),
+			 task_tgid_nr(tsk),
 			 from_kuid(&init_user_ns, audit_get_loginuid(tsk)),
 			 from_kuid(&init_user_ns, cred->uid),
 			 from_kgid(&init_user_ns, cred->gid),

kernel/auditsc.c

@@ -458,7 +458,7 @@ static int audit_filter_rules(struct task_struct *tsk,
 
 		switch (f->type) {
 		case AUDIT_PID:
-			pid = task_pid_nr(tsk);
+			pid = task_tgid_nr(tsk);
 			result = audit_comparator(pid, f->op, f->val);
 			break;
 		case AUDIT_PPID:
@@ -1987,7 +1987,7 @@ static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid,
 	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_LOGIN);
 	if (!ab)
 		return;
-	audit_log_format(ab, "pid=%d uid=%u", task_pid_nr(current), uid);
+	audit_log_format(ab, "pid=%d uid=%u", task_tgid_nr(current), uid);
 	audit_log_task_context(ab);
 	audit_log_format(ab, " old-auid=%u auid=%u old-ses=%u ses=%u res=%d",
 			 oldloginuid, loginuid, oldsessionid, sessionid, !rc);
@@ -2212,7 +2212,7 @@ void __audit_ptrace(struct task_struct *t)
 {
 	struct audit_context *context = current->audit_context;
 
-	context->target_pid = task_pid_nr(t);
+	context->target_pid = task_tgid_nr(t);
 	context->target_auid = audit_get_loginuid(t);
 	context->target_uid = task_uid(t);
 	context->target_sessionid = audit_get_sessionid(t);
@@ -2237,7 +2237,7 @@ int __audit_signal_info(int sig, struct task_struct *t)
 
 	if (audit_pid && t->tgid == audit_pid) {
 		if (sig == SIGTERM || sig == SIGHUP || sig == SIGUSR1 || sig == SIGUSR2) {
-			audit_sig_pid = task_pid_nr(tsk);
+			audit_sig_pid = task_tgid_nr(tsk);
 			if (uid_valid(tsk->loginuid))
 				audit_sig_uid = tsk->loginuid;
 			else
@@ -2337,7 +2337,7 @@ int __audit_log_bprm_fcaps(struct linux_binprm *bprm,
 void __audit_log_capset(const struct cred *new, const struct cred *old)
 {
 	struct audit_context *context = current->audit_context;
-	context->capset.pid = task_pid_nr(current);
+	context->capset.pid = task_tgid_nr(current);
 	context->capset.cap.effective   = new->cap_effective;
 	context->capset.cap.inheritable = new->cap_effective;
 	context->capset.cap.permitted   = new->cap_permitted;
@@ -2369,7 +2369,7 @@ static void audit_log_task(struct audit_buffer *ab)
 			 from_kgid(&init_user_ns, gid),
 			 sessionid);
 	audit_log_task_context(ab);
-	audit_log_format(ab, " pid=%d comm=", task_pid_nr(current));
+	audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current));
 	audit_log_untrustedstring(ab, get_task_comm(comm, current));
 	audit_log_d_path_exe(ab, current->mm);
 }

security/lsm_audit.c

@@ -220,7 +220,7 @@ static void dump_common_audit_data(struct audit_buffer *ab,
 	 */
 	BUILD_BUG_ON(sizeof(a->u) > sizeof(void *)*2);
 
-	audit_log_format(ab, " pid=%d comm=", task_pid_nr(current));
+	audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current));
 	audit_log_untrustedstring(ab, memcpy(comm, current->comm, sizeof(comm)));
 
 	switch (a->type) {
@@ -294,7 +294,7 @@ static void dump_common_audit_data(struct audit_buffer *ab,
 	case LSM_AUDIT_DATA_TASK: {
 		struct task_struct *tsk = a->u.tsk;
 		if (tsk) {
-			pid_t pid = task_pid_nr(tsk);
+			pid_t pid = task_tgid_nr(tsk);
 			if (pid) {
 				char comm[sizeof(tsk->comm)];
 				audit_log_format(ab, " opid=%d ocomm=", pid);