l2tp: do not use udp_ioctl()

commit 72fb96e7bdbbdd4421b0726992496531060f3636 upstream.

udp_ioctl(), as its name suggests, is used by UDP protocols,
but is also used by L2TP :(

L2TP should use its own handler, because it really does not
look the same.

SIOCINQ for instance should not assume UDP checksum or headers.

Thanks to Andrey and syzkaller team for providing the report
and a nice reproducer.

While crashes only happen on recent kernels (after commit
7c13f97ffde6 ("udp: do fwd memory scheduling on dequeue")), this
probably needs to be backported to older kernels.

Fixes: 7c13f97ffde6 ("udp: do fwd memory scheduling on dequeue")
Fixes: 85584672012e ("udp: Fix udp_poll() and ioctl()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index 2f89d43877d795d6262681c63b930e37ef183d5e..a98c854c25276d5392086fa0231c1ab13ad9f81d 100644 (file)
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -256,6 +256,7 @@ extern int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int
 
 extern int l2tp_nl_register_ops(enum l2tp_pwtype pw_type, const struct l2tp_nl_cmd_ops *ops);
 extern void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
+int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 
 /* Session reference counts. Incremented when code obtains a reference
  * to a session.

diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index 07f8b97f9ae9721c4ac70567253638a58d8dd4bf..f4d30b509cdf6aeece02260a545b2aebd185324a 100644 (file)
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -11,6 +11,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <asm/ioctls.h>
 #include <linux/icmp.h>
 #include <linux/module.h>
 #include <linux/skbuff.h>
@@ -554,6 +555,30 @@ out:
        return err ? err : copied;
 }
 
+int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg)
+{
+       struct sk_buff *skb;
+       int amount;
+
+       switch (cmd) {
+       case SIOCOUTQ:
+               amount = sk_wmem_alloc_get(sk);
+               break;
+       case SIOCINQ:
+               spin_lock_bh(&sk->sk_receive_queue.lock);
+               skb = skb_peek(&sk->sk_receive_queue);
+               amount = skb ? skb->len : 0;
+               spin_unlock_bh(&sk->sk_receive_queue.lock);
+               break;
+
+       default:
+               return -ENOIOCTLCMD;
+       }
+
+       return put_user(amount, (int __user *)arg);
+}
+EXPORT_SYMBOL(l2tp_ioctl);
+
 static struct proto l2tp_ip_prot = {
        .name              = "L2TP/IP",
        .owner             = THIS_MODULE,
@@ -562,7 +587,7 @@ static struct proto l2tp_ip_prot = {
        .bind              = l2tp_ip_bind,
        .connect           = l2tp_ip_connect,
        .disconnect        = l2tp_ip_disconnect,
-       .ioctl             = udp_ioctl,
+       .ioctl             = l2tp_ioctl,
        .destroy           = l2tp_ip_destroy_sock,
        .setsockopt        = ip_setsockopt,
        .getsockopt        = ip_getsockopt,

diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
index db96af978da522cdc10b0ccec12a34b03fdc40eb..15367918413c7147255c803c70d677c3b1cdbeef 100644 (file)
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -716,7 +716,7 @@ static struct proto l2tp_ip6_prot = {
        .bind              = l2tp_ip6_bind,
        .connect           = l2tp_ip6_connect,
        .disconnect        = l2tp_ip6_disconnect,
-       .ioctl             = udp_ioctl,
+       .ioctl             = l2tp_ioctl,
        .destroy           = l2tp_ip6_destroy_sock,
        .setsockopt        = ipv6_setsockopt,
        .getsockopt        = ipv6_getsockopt,