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Commit d7ca4cc0 authored by Sridhar Samudrala's avatar Sridhar Samudrala Committed by David S. Miller
Browse files

udpv4: Handle large incoming UDP/IPv4 packets and support software UFO. 



- validate and forward GSO UDP/IPv4 packets from untrusted sources.
- do software UFO if the outgoing device doesn't support UFO.

Signed-off-by: default avatarSridhar Samudrala <sri@us.ibm.com>
Acked-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 30ffee84

include/net/udp.h

+3 −0
Original line number Diff line number Diff line
@@ -207,4 +207,7 @@ extern void udp4_proc_exit(void); 
#endif



extern void udp_init(void);



extern int udp4_ufo_send_check(struct sk_buff *skb);

extern struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb, int features);

#endif	/* _UDP_H */

net/ipv4/af_inet.c

+11 −1
Original line number Diff line number Diff line
@@ -1187,6 +1187,7 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb, int features) 
	int proto;

	int ihl;

	int id;

	unsigned int offset = 0;



	if (!(features & NETIF_F_V4_CSUM))

		features &= ~NETIF_F_SG;
@@ -1229,6 +1230,13 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb, int features) 
	skb = segs;

	do {

		iph = ip_hdr(skb);

		if (proto == IPPROTO_UDP) {

			iph->id = htons(id);

			iph->frag_off = htons(offset >> 3);

			if (skb->next != NULL)

				iph->frag_off |= htons(IP_MF);

			offset += (skb->len - skb->mac_len - iph->ihl * 4);

		} else

			iph->id = htons(id++);

		iph->tot_len = htons(skb->len - skb->mac_len);

		iph->check = 0;
@@ -1425,6 +1433,8 @@ static struct net_protocol tcp_protocol = { 
static struct net_protocol udp_protocol = {

	.handler =	udp_rcv,

	.err_handler =	udp_err,

	.gso_send_check = udp4_ufo_send_check,

	.gso_segment = udp4_ufo_fragment,

	.no_policy =	1,

	.netns_ok =	1,

};

net/ipv4/udp.c

+61 −0
Original line number Diff line number Diff line
@@ -1816,6 +1816,67 @@ void __init udp_init(void) 
	sysctl_udp_wmem_min = SK_MEM_QUANTUM;

}



int udp4_ufo_send_check(struct sk_buff *skb)

{

	const struct iphdr *iph;

	struct udphdr *uh;



	if (!pskb_may_pull(skb, sizeof(*uh)))

		return -EINVAL;



	iph = ip_hdr(skb);

	uh = udp_hdr(skb);



	uh->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr, skb->len,

				       IPPROTO_UDP, 0);

	skb->csum_start = skb_transport_header(skb) - skb->head;

	skb->csum_offset = offsetof(struct udphdr, check);

	skb->ip_summed = CHECKSUM_PARTIAL;

	return 0;

}



struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb, int features)

{

	struct sk_buff *segs = ERR_PTR(-EINVAL);

	unsigned int mss;

	int offset;

	__wsum csum;



	mss = skb_shinfo(skb)->gso_size;

	if (unlikely(skb->len <= mss))

		goto out;



	if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {

		/* Packet is from an untrusted source, reset gso_segs. */

		int type = skb_shinfo(skb)->gso_type;



		if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY) ||

			     !(type & (SKB_GSO_UDP))))

			goto out;



		skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);



		segs = NULL;

		goto out;

	}



	/* Do software UFO. Complete and fill in the UDP checksum as HW cannot

	 * do checksum of UDP packets sent as multiple IP fragments.

	 */

	offset = skb->csum_start - skb_headroom(skb);

	csum = skb_checksum(skb, offset, skb->len- offset, 0);

	offset += skb->csum_offset;

	*(__sum16 *)(skb->data + offset) = csum_fold(csum);

	skb->ip_summed = CHECKSUM_NONE;



	/* Fragment the skb. IP headers of the fragments are updated in

	 * inet_gso_segment()

	 */

	segs = skb_segment(skb, features);

out:

	return segs;

}



EXPORT_SYMBOL(udp_disconnect);

EXPORT_SYMBOL(udp_ioctl);

EXPORT_SYMBOL(udp_prot);