[bpf-next PATCH 1/7] net: add a UID to use for ULP socket assignment

[John Fastabend <john.fastabend@gmail.com>]

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
as a TX hook for TCP sockets. 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.

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>
---
 include/net/tcp.h  |    5 +++++
 net/ipv4/tcp_ulp.c |   51 ++++++++++++++++++++++++++++++++++++++++++++++-----
 net/tls/tls_main.c |    1 +
 3 files changed, 52 insertions(+), 5 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 6939e69..a99ceb8 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1982,6 +1982,10 @@ static inline void tcp_listendrop(const struct sock *sk)
 #define TCP_ULP_MAX		128
 #define TCP_ULP_BUF_MAX		(TCP_ULP_NAME_MAX*TCP_ULP_MAX)
 
+enum {
+	TCP_ULP_TLS,
+};
+
 struct tcp_ulp_ops {
 	struct list_head	list;
 
@@ -1990,6 +1994,7 @@ struct tcp_ulp_ops {
 	/* cleanup ulp */
 	void (*release)(struct sock *sk);
 
+	int		uid;
 	char		name[TCP_ULP_NAME_MAX];
 	struct module	*owner;
 };
diff --git a/net/ipv4/tcp_ulp.c b/net/ipv4/tcp_ulp.c
index 6bb9e14..58cadc5 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 +63,19 @@ 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 = NULL;
+
+	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 +84,10 @@ 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;
@@ -133,3 +155,22 @@ int tcp_set_ulp(struct sock *sk, const char *name)
 	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)
+		icsk->icsk_ulp_ops = ulp_ops;
+	return err;
+}
diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index e07ee3a..1563a9e 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -473,6 +473,7 @@ static int tls_init(struct sock *sk)
 
 static struct tcp_ulp_ops tcp_tls_ulp_ops __read_mostly = {
 	.name			= "tls",
+	.uid			= TCP_ULP_TLS,
 	.owner			= THIS_MODULE,
 	.init			= tls_init,
 };