net: add a UID to use for ULP socket assignment

Web:        https://git.kernel.org/torvalds/c/b11a632c442eef34a0afeba61fab923241f317e9
Commit:     b11a632c442eef34a0afeba61fab923241f317e9
Parent:     7b4eb53d95c30bdc55c44647c6968f24227fd1ba
Refname:    refs/heads/master
Author:     John Fastabend <[email protected]>
AuthorDate: Mon Feb 5 10:17:43 2018 -0800
Committer:  Daniel Borkmann <[email protected]>
CommitDate: Tue Feb 6 11:39:31 2018 +0100

    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 <[email protected]>
    Signed-off-by: Daniel Borkmann <[email protected]>
---
 include/net/tcp.h  |  6 ++++++
 net/ipv4/tcp_ulp.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++++-----
 net/tls/tls_main.c |  2 ++
 3 files changed, 62 insertions(+), 5 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 58278669cc55..a58292d31e12 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1983,6 +1983,10 @@ enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
 #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;
 
@@ -1991,7 +1995,9 @@ struct tcp_ulp_ops {
 	/* cleanup ulp */
 	void (*release)(struct sock *sk);
 
+	int		uid;
 	char		name[TCP_ULP_NAME_MAX];
+	bool		user_visible;
 	struct module	*owner;
 };
 int tcp_register_ulp(struct tcp_ulp_ops *type);
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,
 };
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