[PATCH] collect sid of those who send signals to auditd

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

include/linux/audit.h

@@ -278,6 +278,7 @@ struct audit_rule {		/* for AUDIT_LIST, AUDIT_ADD, and AUDIT_DEL */
 struct audit_sig_info {
 	uid_t		uid;
 	pid_t		pid;
+	char		ctx[0];
 };
 
 struct audit_buffer;
@@ -328,7 +329,6 @@ extern int audit_bprm(struct linux_binprm *bprm);
 extern int audit_socketcall(int nargs, unsigned long *args);
 extern int audit_sockaddr(int len, void *addr);
 extern int audit_avc_path(struct dentry *dentry, struct vfsmount *mnt);
-extern void audit_signal_info(int sig, struct task_struct *t);
 extern int audit_set_macxattr(const char *name);
 #else
 #define audit_alloc(t) ({ 0; })
@@ -349,7 +349,6 @@ extern int audit_set_macxattr(const char *name);
 #define audit_socketcall(n,a) ({ 0; })
 #define audit_sockaddr(len, addr) ({ 0; })
 #define audit_avc_path(dentry, mnt) ({ 0; })
-#define audit_signal_info(s,t) do { ; } while (0)
 #define audit_set_macxattr(n) do { ; } while (0)
 #endif
 

kernel/audit.c

@@ -89,6 +89,7 @@ static int	audit_backlog_wait_overflow = 0;
 /* The identity of the user shutting down the audit system. */
 uid_t		audit_sig_uid = -1;
 pid_t		audit_sig_pid = -1;
+u32		audit_sig_sid = 0;
 
 /* Records can be lost in several ways:
    0) [suppressed in audit_alloc]
@@ -479,7 +480,9 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 	struct audit_buffer	*ab;
 	u16			msg_type = nlh->nlmsg_type;
 	uid_t			loginuid; /* loginuid of sender */
-	struct audit_sig_info   sig_data;
+	struct audit_sig_info   *sig_data;
+	char			*ctx;
+	u32			len;
 
 	err = audit_netlink_ok(NETLINK_CB(skb).eff_cap, msg_type);
 	if (err)
@@ -531,12 +534,9 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 		if (status_get->mask & AUDIT_STATUS_PID) {
 			int old   = audit_pid;
 			if (sid) {
-				char *ctx = NULL;
-				u32 len;
-				int rc;
-				if ((rc = selinux_ctxid_to_string(
+				if ((err = selinux_ctxid_to_string(
 						sid, &ctx, &len)))
-					return rc;
+					return err;
 				else
 					audit_log(NULL, GFP_KERNEL,
 						AUDIT_CONFIG_CHANGE,
@@ -572,8 +572,6 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 						 "user pid=%d uid=%u auid=%u",
 						 pid, uid, loginuid);
 				if (sid) {
-					char *ctx = NULL;
-					u32 len;
 					if (selinux_ctxid_to_string(
 							sid, &ctx, &len)) {
 						audit_log_format(ab, 
@@ -612,10 +610,21 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 					   loginuid, sid);
 		break;
 	case AUDIT_SIGNAL_INFO:
-		sig_data.uid = audit_sig_uid;
-		sig_data.pid = audit_sig_pid;
+		err = selinux_ctxid_to_string(audit_sig_sid, &ctx, &len);
+		if (err)
+			return err;
+		sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
+		if (!sig_data) {
+			kfree(ctx);
+			return -ENOMEM;
+		}
+		sig_data->uid = audit_sig_uid;
+		sig_data->pid = audit_sig_pid;
+		memcpy(sig_data->ctx, ctx, len);
+		kfree(ctx);
 		audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO, 
-				0, 0, &sig_data, sizeof(sig_data));
+				0, 0, sig_data, sizeof(*sig_data) + len);
+		kfree(sig_data);
 		break;
 	default:
 		err = -EINVAL;

kernel/audit.h

@@ -101,3 +101,14 @@ struct audit_netlink_list {
 int audit_send_list(void *);
 
 extern int selinux_audit_rule_update(void);
+
+#ifdef CONFIG_AUDITSYSCALL
+extern void __audit_signal_info(int sig, struct task_struct *t);
+static inline void audit_signal_info(int sig, struct task_struct *t)
+{
+	if (unlikely(audit_pid && t->tgid == audit_pid))
+		__audit_signal_info(sig, t);
+}
+#else
+#define audit_signal_info(s,t)
+#endif

kernel/auditsc.c

@@ -1376,19 +1376,20 @@ int audit_avc_path(struct dentry *dentry, struct vfsmount *mnt)
  * If the audit subsystem is being terminated, record the task (pid)
  * and uid that is doing that.
  */
-void audit_signal_info(int sig, struct task_struct *t)
+void __audit_signal_info(int sig, struct task_struct *t)
 {
 	extern pid_t audit_sig_pid;
 	extern uid_t audit_sig_uid;
-
-	if (unlikely(audit_pid && t->tgid == audit_pid)) {
-		if (sig == SIGTERM || sig == SIGHUP) {
-			struct audit_context *ctx = current->audit_context;
-			audit_sig_pid = current->pid;
-			if (ctx)
-				audit_sig_uid = ctx->loginuid;
-			else
-				audit_sig_uid = current->uid;
-		}
+	extern u32 audit_sig_sid;
+
+	if (sig == SIGTERM || sig == SIGHUP || sig == SIGUSR1) {
+		struct task_struct *tsk = current;
+		struct audit_context *ctx = tsk->audit_context;
+		audit_sig_pid = tsk->pid;
+		if (ctx)
+			audit_sig_uid = ctx->loginuid;
+		else
+			audit_sig_uid = tsk->uid;
+		selinux_get_task_sid(tsk, &audit_sig_sid);
 	}
 }

kernel/signal.c

@@ -23,12 +23,12 @@
 #include <linux/syscalls.h>
 #include <linux/ptrace.h>
 #include <linux/signal.h>
-#include <linux/audit.h>
 #include <linux/capability.h>
 #include <asm/param.h>
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
 #include <asm/siginfo.h>
+#include "audit.h"	/* audit_signal_info() */
 
 /*
  * SLAB caches for signal bits.