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: Sridhar Samudrala <sri@us.ibm.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/udp.h b/include/net/udp.h
index 90e6ce5..5fb029f 100644 (file)
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -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 */

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 566ea6c..197d024 100644 (file)
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -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;
@@ -1229,7 +1230,14 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb, int features)
        skb = segs;
        do {
                iph = ip_hdr(skb);
-               iph->id = htons(id++);
+               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;
                iph->check = ip_fast_csum(skb_network_header(skb), iph->ihl);
@@ -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,
 };

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 80e3812..7bc2d08 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -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);