net: add a UID to use for ULP socket assignment

Create a UID field and enum that can be used to assign ULPs to
sockets. This saves a set of string comparisons if the ULP id
is known.

For sockmap, which is added in the next patches, a ULP is used to
hook into TCP sockets close state. In this case the ULP being added
is done at map insert time and the ULP is known and done on the kernel
side. In this case the named lookup is not needed. Because we don't
want to expose psock internals to user space socket options a user
visible flag is also added. For TLS this is set for BPF it will be
cleared.

Alos remove pr_notice, user gets an error code back and should check
that rather than rely on logs.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

2 files changed, 56 insertions, 5 deletions

diff --git a/net/ipv4/tcp_ulp.c b/net/ipv4/tcp_ulp.c
index 6bb9e14c710a..622caa4039e0 100644
--- a/net/ipv4/tcp_ulp.c
+++ b/net/ipv4/tcp_ulp.c
@@ -29,6 +29,18 @@ static struct tcp_ulp_ops *tcp_ulp_find(const char *name)
 	return NULL;
 }
 
+static struct tcp_ulp_ops *tcp_ulp_find_id(const int ulp)
+{
+	struct tcp_ulp_ops *e;
+
+	list_for_each_entry_rcu(e, &tcp_ulp_list, list) {
+		if (e->uid == ulp)
+			return e;
+	}
+
+	return NULL;
+}
+
 static const struct tcp_ulp_ops *__tcp_ulp_find_autoload(const char *name)
 {
 	const struct tcp_ulp_ops *ulp = NULL;
@@ -51,6 +63,18 @@ static const struct tcp_ulp_ops *__tcp_ulp_find_autoload(const char *name)
 	return ulp;
 }
 
+static const struct tcp_ulp_ops *__tcp_ulp_lookup(const int uid)
+{
+	const struct tcp_ulp_ops *ulp;
+
+	rcu_read_lock();
+	ulp = tcp_ulp_find_id(uid);
+	if (!ulp || !try_module_get(ulp->owner))
+		ulp = NULL;
+	rcu_read_unlock();
+	return ulp;
+}
+
 /* Attach new upper layer protocol to the list
  * of available protocols.
  */
@@ -59,13 +83,10 @@ int tcp_register_ulp(struct tcp_ulp_ops *ulp)
 	int ret = 0;
 
 	spin_lock(&tcp_ulp_list_lock);
-	if (tcp_ulp_find(ulp->name)) {
-		pr_notice("%s already registered or non-unique name\n",
-			  ulp->name);
+	if (tcp_ulp_find(ulp->name))
 		ret = -EEXIST;
-	} else {
+	else
 		list_add_tail_rcu(&ulp->list, &tcp_ulp_list);
-	}
 	spin_unlock(&tcp_ulp_list_lock);
 
 	return ret;
@@ -124,6 +145,34 @@ int tcp_set_ulp(struct sock *sk, const char *name)
 	if (!ulp_ops)
 		return -ENOENT;
 
+	if (!ulp_ops->user_visible) {
+		module_put(ulp_ops->owner);
+		return -ENOENT;
+	}
+
+	err = ulp_ops->init(sk);
+	if (err) {
+		module_put(ulp_ops->owner);
+		return err;
+	}
+
+	icsk->icsk_ulp_ops = ulp_ops;
+	return 0;
+}
+
+int tcp_set_ulp_id(struct sock *sk, int ulp)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+	const struct tcp_ulp_ops *ulp_ops;
+	int err;
+
+	if (icsk->icsk_ulp_ops)
+		return -EEXIST;
+
+	ulp_ops = __tcp_ulp_lookup(ulp);
+	if (!ulp_ops)
+		return -ENOENT;
+
 	err = ulp_ops->init(sk);
 	if (err) {
 		module_put(ulp_ops->owner);
diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index 736719c8314e..b0d5fcea47e7 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -484,6 +484,8 @@ out:
 
 static struct tcp_ulp_ops tcp_tls_ulp_ops __read_mostly = {
 	.name			= "tls",
+	.uid			= TCP_ULP_TLS,
+	.user_visible		= true,
 	.owner			= THIS_MODULE,
 	.init			= tls_init,
 };