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Commit 9c707762 authored by Willem de Bruijn's avatar Willem de Bruijn Committed by David S. Miller
Browse files

packet: make packet_snd fail on len smaller than l2 header 



When sending packets out with PF_PACKET, SOCK_RAW, ensure that the
packet is at least as long as the device's expected link layer header.
This check already exists in tpacket_snd, but not in packet_snd.
Also rate limit the warning in tpacket_snd.

Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent df6ce470

net/packet/af_packet.c

+21 −8
Original line number Diff line number Diff line
@@ -2095,6 +2095,18 @@ static void tpacket_destruct_skb(struct sk_buff *skb) 
	sock_wfree(skb);

}



static bool ll_header_truncated(const struct net_device *dev, int len)

{

	/* net device doesn't like empty head */

	if (unlikely(len <= dev->hard_header_len)) {

		net_warn_ratelimited("%s: packet size is too short (%d < %d)\n",

				     current->comm, len, dev->hard_header_len);

		return true;

	}



	return false;

}



static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,

		void *frame, struct net_device *dev, int size_max,

		__be16 proto, unsigned char *addr, int hlen)
@@ -2170,12 +2182,8 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb, 
		if (unlikely(err < 0))

			return -EINVAL;

	} else if (dev->hard_header_len) {

		/* net device doesn't like empty head */

		if (unlikely(tp_len <= dev->hard_header_len)) {

			pr_err("packet size is too short (%d < %d)\n",

			       tp_len, dev->hard_header_len);

		if (ll_header_truncated(dev, tp_len))

			return -EINVAL;

		}



		skb_push(skb, dev->hard_header_len);

		err = skb_store_bits(skb, 0, data,
@@ -2500,9 +2508,14 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len) 
	skb_set_network_header(skb, reserve);



	err = -EINVAL;

	if (sock->type == SOCK_DGRAM &&

	    (offset = dev_hard_header(skb, dev, ntohs(proto), addr, NULL, len)) < 0)

	if (sock->type == SOCK_DGRAM) {

		offset = dev_hard_header(skb, dev, ntohs(proto), addr, NULL, len);

		if (unlikely(offset) < 0)

			goto out_free;

	} else {

		if (ll_header_truncated(dev, len))

			goto out_free;

	}



	/* Returns -EFAULT on error */

	err = skb_copy_datagram_from_iovec(skb, offset, msg->msg_iov, 0, len);