tcp: md5: use sock_kmalloc() to limit md5 keys

There is no limit on number of MD5 keys an application can attach to a
tcp socket.

This patch adds a per tcp socket limit based
on /proc/sys/net/core/optmem_max

With current default optmem_max values, this allows about 150 keys on
64bit arches, and 88 keys on 32bit arches.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 2 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 1d5fd82c5c0..da5d3226771 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -943,11 +943,11 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
                 tp->md5sig_info = md5sig;
         }
 
-        key = kmalloc(sizeof(*key), gfp);
+        key = sock_kmalloc(sk, sizeof(*key), gfp);
         if (!key)
                 return -ENOMEM;
         if (hlist_empty(&md5sig->head) && !tcp_alloc_md5sig_pool(sk)) {
-                kfree(key);
+                sock_kfree_s(sk, key, sizeof(*key));
                 return -ENOMEM;
         }
 
@@ -971,6 +971,7 @@ int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, int family)
         if (!key)
                 return -ENOENT;
         hlist_del_rcu(&key->node);
+        atomic_sub(sizeof(*key), &sk->sk_omem_alloc);
         kfree_rcu(key, rcu);
         if (hlist_empty(&tp->md5sig_info->head))
                 tcp_free_md5sig_pool();
@@ -988,6 +989,7 @@ void tcp_clear_md5_list(struct sock *sk)
                 tcp_free_md5sig_pool();
         hlist_for_each_entry_safe(key, pos, n, &tp->md5sig_info->head, node) {
                 hlist_del_rcu(&key->node);
+                atomic_sub(sizeof(*key), &sk->sk_omem_alloc);
                 kfree_rcu(key, rcu);
         }
 }