[PATCH v6 18/26] tcp: authopt: Add /proc/net/tcp_authopt listing all keys

[Leonard Crestez <cdleonard@gmail.com>]

This provides a very brief summary of all keys for debugging purposes.

Signed-off-by: Leonard Crestez <cdleonard@gmail.com>
---
 Documentation/networking/tcp_authopt.rst |  10 +++
 net/ipv4/tcp_authopt.c                   | 102 ++++++++++++++++++++++-
 2 files changed, 111 insertions(+), 1 deletion(-)

diff --git a/Documentation/networking/tcp_authopt.rst b/Documentation/networking/tcp_authopt.rst
index 6520c6d02755..eaf389f99139 100644
--- a/Documentation/networking/tcp_authopt.rst
+++ b/Documentation/networking/tcp_authopt.rst
@@ -69,10 +69,20 @@ The rnextkeyid value sent on the wire is usually the recv_id of the current
 key used for sending. If the TCP_AUTHOPT_LOCK_RNEXTKEY flag is set in
 `tcp_authopt.flags` the value of `tcp_authopt.send_rnextkeyid` is send
 instead.  This can be used to implement smooth rollover: the peer will switch
 its keyid to the received rnextkeyid when it is available.
 
+Proc interface
+--------------
+
+The ``/proc/net/tcp_authopt`` file contains a tab-separated table of keys. The
+first line contains column names. The number of columns might increase in the
+future if more matching criteria are added. Here is an example of the table::
+
+	flags	send_id	recv_id	alg	addr	l3index
+	0x44	0	0	1	10.10.2.2/31	0
+
 ABI Reference
 =============
 
 .. kernel-doc:: include/uapi/linux/tcp.h
    :identifiers: tcp_authopt tcp_authopt_flag tcp_authopt_key tcp_authopt_key_flag tcp_authopt_alg
diff --git a/net/ipv4/tcp_authopt.c b/net/ipv4/tcp_authopt.c
index e4aecd35ffda..00d749aa1025 100644
--- a/net/ipv4/tcp_authopt.c
+++ b/net/ipv4/tcp_authopt.c
@@ -5,10 +5,11 @@
 #include <net/ipv6.h>
 #include <net/tcp.h>
 #include <linux/kref.h>
 #include <crypto/hash.h>
 #include <linux/inetdevice.h>
+#include <linux/proc_fs.h>
 
 /* This is mainly intended to protect against local privilege escalations through
  * a rarely used feature so it is deliberately not namespaced.
  */
 int sysctl_tcp_authopt;
@@ -1716,26 +1717,125 @@ int __tcp_authopt_inbound_check(struct sock *sk, struct sk_buff *skb,
 
 	return 1;
 }
 EXPORT_SYMBOL(__tcp_authopt_inbound_check);
 
+#ifdef CONFIG_PROC_FS
+struct tcp_authopt_iter_state {
+	struct seq_net_private p;
+};
+
+static struct tcp_authopt_key_info *tcp_authopt_get_key_index(struct netns_tcp_authopt *net,
+							      int index)
+{
+	struct tcp_authopt_key_info *key;
+
+	hlist_for_each_entry(key, &net->head, node) {
+		if (--index < 0)
+			return key;
+	}
+
+	return NULL;
+}
+
+static void *tcp_authopt_seq_start(struct seq_file *seq, loff_t *pos)
+	__acquires(RCU)
+{
+	struct netns_tcp_authopt *net = &seq_file_net(seq)->tcp_authopt;
+
+	rcu_read_lock();
+	if (*pos == 0)
+		return SEQ_START_TOKEN;
+	else
+		return tcp_authopt_get_key_index(net, *pos - 1);
+}
+
+static void tcp_authopt_seq_stop(struct seq_file *seq, void *v)
+	__releases(RCU)
+{
+	rcu_read_unlock();
+}
+
+static void *tcp_authopt_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct netns_tcp_authopt *net = &seq_file_net(seq)->tcp_authopt;
+	void *ret;
+
+	ret = tcp_authopt_get_key_index(net, *pos);
+	++*pos;
+
+	return ret;
+}
+
+static int tcp_authopt_seq_show(struct seq_file *seq, void *v)
+{
+	struct tcp_authopt_key_info *key = v;
+
+	/* FIXME: Document somewhere */
+	/* Key is deliberately inaccessible */
+	if (v == SEQ_START_TOKEN) {
+		seq_puts(seq, "flags\tsend_id\trecv_id\talg\taddr\tl3index\n");
+		return 0;
+	}
+
+	seq_printf(seq, "0x%x\t%d\t%d\t%d",
+		   key->flags, key->send_id, key->recv_id, (int)key->alg_id);
+	if (key->flags & TCP_AUTHOPT_KEY_ADDR_BIND) {
+		if (key->addr.ss_family == AF_INET6)
+			seq_printf(seq, "\t%pI6", &((struct sockaddr_in6 *)&key->addr)->sin6_addr);
+		else
+			seq_printf(seq, "\t%pI4", &((struct sockaddr_in *)&key->addr)->sin_addr);
+		if (key->flags & TCP_AUTHOPT_KEY_PREFIXLEN)
+			seq_printf(seq, "/%d", key->prefixlen);
+	} else {
+		seq_puts(seq, "\t*");
+	}
+	seq_printf(seq, "\t%d", key->l3index);
+	seq_puts(seq, "\n");
+
+	return 0;
+}
+
+static const struct seq_operations tcp_authopt_seq_ops = {
+	.start		= tcp_authopt_seq_start,
+	.next		= tcp_authopt_seq_next,
+	.stop		= tcp_authopt_seq_stop,
+	.show		= tcp_authopt_seq_show,
+};
+#endif /* CONFIG_PROC_FS */
+
+static int __net_init tcp_authopt_proc_init_net(struct net *net)
+{
+	if (!proc_create_net("tcp_authopt", 0400, net->proc_net,
+			     &tcp_authopt_seq_ops,
+			     sizeof(struct tcp_authopt_iter_state)))
+		return -ENOMEM;
+	return 0;
+}
+
+static void __net_exit tcp_authopt_proc_exit_net(struct net *net)
+{
+	remove_proc_entry("tcp_authopt", net->proc_net);
+}
+
 static int tcp_authopt_init_net(struct net *full_net)
 {
 	struct netns_tcp_authopt *net = &full_net->tcp_authopt;
 
 	mutex_init(&net->mutex);
 	INIT_HLIST_HEAD(&net->head);
 
-	return 0;
+	return tcp_authopt_proc_init_net(full_net);
 }
 
 static void tcp_authopt_exit_net(struct net *full_net)
 {
 	struct netns_tcp_authopt *net = &full_net->tcp_authopt;
 	struct tcp_authopt_key_info *key;
 	struct hlist_node *n;
 
+	tcp_authopt_proc_exit_net(full_net);
 	mutex_lock(&net->mutex);
 
 	hlist_for_each_entry_safe(key, n, &net->head, node) {
 		hlist_del_rcu(&key->node);
 		tcp_authopt_key_put(key);
-- 
2.25.1