[PATCH v7 18/26] tcp: authopt: Add /proc/net/tcp_authopt listing all keys

From: Leonard Crestez
Date: Thu Aug 18 2022 - 16:02:39 EST


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

Signed-off-by: Leonard Crestez <cdleonard@xxxxxxxxx>
---
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 06f8df1d80c9..0a273ad239ec 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;
@@ -1731,26 +1732,125 @@ 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