[PATCH ghak90 V9 06/13] audit: add contid support for signalling the audit daemon

@@ -22,6 +22,13 @@ struct audit_sig_info {
 	char		ctx[];
 };
 
+struct audit_sig_info2 {
+	uid_t		uid;
+	pid_t		pid;
+	u32		cid_len;
+	char		data[];
+};
+
 struct audit_buffer;
 struct audit_context;
 struct inode;

@@ -105,6 +112,7 @@ struct audit_contobj {
 	u64			id;
 	struct task_struct	*owner;
 	refcount_t		refcount;
+	refcount_t		sigflag;
 	struct rcu_head         rcu;
 };
 

@@ -72,6 +72,7 @@
 #define AUDIT_SET_FEATURE	1018	/* Turn an audit feature on or off */
 #define AUDIT_GET_FEATURE	1019	/* Get which features are enabled */
 #define AUDIT_CONTAINER_OP	1020	/* Define the container id and info */
+#define AUDIT_SIGNAL_INFO2	1021	/* Get info auditd signal sender */
 
 #define AUDIT_FIRST_USER_MSG	1100	/* Userspace messages mostly uninteresting to kernel */
 #define AUDIT_USER_AVC		1107	/* We filter this differently */

@@ -126,6 +126,8 @@ struct auditd_connection {
 kuid_t		audit_sig_uid = INVALID_UID;
 pid_t		audit_sig_pid = -1;
 u32		audit_sig_sid = 0;
+static struct audit_contobj *audit_sig_cid;
+static struct task_struct *audit_sig_atsk;
 
 /* Records can be lost in several ways:
    0) [suppressed in audit_alloc]

@@ -239,7 +241,33 @@ void _audit_contobj_put(struct audit_contobj *cont)
 {
 	if (!cont)
 		return;
-	if (refcount_dec_and_test(&cont->refcount)) {
+	if (refcount_dec_and_test(&cont->refcount) && !refcount_read(&cont->sigflag)) {
+		put_task_struct(cont->owner);
+		list_del_rcu(&cont->list);
+		kfree_rcu(cont, rcu);
+	}
+}
+
+/* rcu_read_lock must be held by caller unless new */
+static struct audit_contobj *_audit_contobj_get_sig(struct task_struct *tsk)
+{
+	struct audit_contobj *cont;
+
+	if (!tsk->audit)
+		return NULL;
+	cont = tsk->audit->cont;
+	if (cont)
+		refcount_set(&cont->sigflag, 1);
+	return cont;
+}
+
+/* rcu_read_lock must be held by caller */
+static void _audit_contobj_put_sig(struct audit_contobj *cont)
+{
+	if (!cont)
+		return;
+	refcount_set(&cont->sigflag, 0);
+	if (!refcount_read(&cont->refcount)) {
 		put_task_struct(cont->owner);
 		list_del_rcu(&cont->list);
 		kfree_rcu(cont, rcu);

@@ -309,6 +337,13 @@ void audit_free(struct task_struct *tsk)
 	info = tsk->audit;
 	tsk->audit = NULL;
 	kmem_cache_free(audit_task_cache, info);
+	rcu_read_lock();
+	if (audit_sig_atsk == tsk) {
+		_audit_contobj_put_sig(audit_sig_cid);
+		audit_sig_cid = NULL;
+		audit_sig_atsk = NULL;
+	}
+	rcu_read_unlock();
 }
 
 /**

@@ -1132,6 +1167,7 @@ static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
 	case AUDIT_ADD_RULE:
 	case AUDIT_DEL_RULE:
 	case AUDIT_SIGNAL_INFO:
+	case AUDIT_SIGNAL_INFO2:
 	case AUDIT_TTY_GET:
 	case AUDIT_TTY_SET:
 	case AUDIT_TRIM:

@@ -1294,6 +1330,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 	struct audit_buffer	*ab;
 	u16			msg_type = nlh->nlmsg_type;
 	struct audit_sig_info   *sig_data;
+	struct audit_sig_info2  *sig_data2;
 	char			*ctx = NULL;
 	u32			len;
 

@@ -1559,6 +1596,52 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 				 sig_data, sizeof(*sig_data) + len);
 		kfree(sig_data);
 		break;
+	case AUDIT_SIGNAL_INFO2: {
+		unsigned int contidstrlen = 0;
+
+		len = 0;
+		if (audit_sig_sid) {
+			err = security_secid_to_secctx(audit_sig_sid, &ctx,
+						       &len);
+			if (err)
+				return err;
+		}
+		if (audit_sig_cid) {
+			contidstr = kmalloc(21, GFP_KERNEL);
+			if (!contidstr) {
+				if (audit_sig_sid)
+					security_release_secctx(ctx, len);
+				return -ENOMEM;
+			}
+			contidstrlen = scnprintf(contidstr, 20, "%llu", audit_sig_cid->id);
+		}
+		sig_data2 = kmalloc(sizeof(*sig_data2) + contidstrlen + len, GFP_KERNEL);
+		if (!sig_data2) {
+			if (audit_sig_sid)
+				security_release_secctx(ctx, len);
+			kfree(contidstr);
+			return -ENOMEM;
+		}
+		sig_data2->uid = from_kuid(&init_user_ns, audit_sig_uid);
+		sig_data2->pid = audit_sig_pid;
+		if (audit_sig_cid) {
+			memcpy(sig_data2->data, contidstr, contidstrlen);
+			sig_data2->cid_len = contidstrlen;
+			kfree(contidstr);
+		}
+		if (audit_sig_sid) {
+			memcpy(sig_data2->data + contidstrlen, ctx, len);
+			security_release_secctx(ctx, len);
+		}
+		rcu_read_lock();
+		_audit_contobj_put_sig(audit_sig_cid);
+		rcu_read_unlock();
+		audit_sig_cid = NULL;
+		audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO2, 0, 0,
+				 sig_data2, sizeof(*sig_data2) + contidstrlen + len);
+		kfree(sig_data2);
+		break;
+	}
 	case AUDIT_TTY_GET: {
 		struct audit_tty_status s;
 		unsigned int t;

@@ -2470,6 +2553,11 @@ int audit_signal_info(int sig, struct task_struct *t)
 		else
 			audit_sig_uid = uid;
 		security_task_getsecid(current, &audit_sig_sid);
+		rcu_read_lock();
+		_audit_contobj_put_sig(audit_sig_cid);
+		audit_sig_cid = _audit_contobj_get_sig(current);
+		rcu_read_unlock();
+		audit_sig_atsk = t;
 	}
 
 	return audit_signal_info_syscall(t);

@@ -2532,6 +2620,11 @@ int audit_set_contid(struct task_struct *task, u64 contid)
 			if (cont->id == contid) {
 				/* task injection to existing container */
 				if (current == cont->owner) {
+					if (!refcount_read(&cont->refcount)) {
+						rc = -ESHUTDOWN;
+						spin_unlock(&audit_contobj_list_lock);
+						goto conterror;
+					}
 					_audit_contobj_hold(cont);
 					newcont = cont;
 				} else {

@@ -137,6 +137,7 @@ struct nlmsg_perm {
 	{ AUDIT_DEL_RULE,	NETLINK_AUDIT_SOCKET__NLMSG_WRITE    },
 	{ AUDIT_USER,		NETLINK_AUDIT_SOCKET__NLMSG_RELAY    },
 	{ AUDIT_SIGNAL_INFO,	NETLINK_AUDIT_SOCKET__NLMSG_READ     },
+	{ AUDIT_SIGNAL_INFO2,	NETLINK_AUDIT_SOCKET__NLMSG_READ     },
 	{ AUDIT_TRIM,		NETLINK_AUDIT_SOCKET__NLMSG_WRITE    },
 	{ AUDIT_MAKE_EQUIV,	NETLINK_AUDIT_SOCKET__NLMSG_WRITE    },
 	{ AUDIT_TTY_GET,	NETLINK_AUDIT_SOCKET__NLMSG_READ     },