![Alexander Duyck](/assets/img/avatar_default.png)
On reviewing the code I realized that GRE and UDP tunnels could cause a kernel panic if we used GSO to segment a large UDP frame that was sent through the tunnel with an outer checksum and hardware offloads were not available. In order to correct this we need to update the feature flags that are passed to the skb_segment function so that in the event of UDP fragmentation being requested for the inner header the segmentation function will correctly generate the checksum for the payload if we cannot segment the outer header. Signed-off-by: Alexander Duyck <aduyck@mirantis.com> Signed-off-by: David S. Miller <davem@davemloft.net>
191 lines
5.1 KiB
C
191 lines
5.1 KiB
C
/*
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* IPV6 GSO/GRO offload support
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* Linux INET6 implementation
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* UDPv6 GSO support
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*/
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#include <linux/skbuff.h>
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#include <linux/netdevice.h>
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#include <net/protocol.h>
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#include <net/ipv6.h>
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#include <net/udp.h>
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#include <net/ip6_checksum.h>
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#include "ip6_offload.h"
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static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
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netdev_features_t features)
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{
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struct sk_buff *segs = ERR_PTR(-EINVAL);
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unsigned int mss;
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unsigned int unfrag_ip6hlen, unfrag_len;
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struct frag_hdr *fptr;
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u8 *packet_start, *prevhdr;
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u8 nexthdr;
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u8 frag_hdr_sz = sizeof(struct frag_hdr);
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__wsum csum;
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int tnl_hlen;
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mss = skb_shinfo(skb)->gso_size;
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if (unlikely(skb->len <= mss))
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goto out;
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if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
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/* Packet is from an untrusted source, reset gso_segs. */
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int type = skb_shinfo(skb)->gso_type;
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if (unlikely(type & ~(SKB_GSO_UDP |
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SKB_GSO_DODGY |
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SKB_GSO_UDP_TUNNEL |
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SKB_GSO_UDP_TUNNEL_CSUM |
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SKB_GSO_TUNNEL_REMCSUM |
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SKB_GSO_GRE |
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SKB_GSO_GRE_CSUM |
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SKB_GSO_IPIP |
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SKB_GSO_SIT) ||
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!(type & (SKB_GSO_UDP))))
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goto out;
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skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
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/* Set the IPv6 fragment id if not set yet */
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if (!skb_shinfo(skb)->ip6_frag_id)
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ipv6_proxy_select_ident(dev_net(skb->dev), skb);
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segs = NULL;
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goto out;
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}
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if (skb->encapsulation && skb_shinfo(skb)->gso_type &
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(SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
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segs = skb_udp_tunnel_segment(skb, features, true);
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else {
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const struct ipv6hdr *ipv6h;
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struct udphdr *uh;
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if (!pskb_may_pull(skb, sizeof(struct udphdr)))
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goto out;
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/* Do software UFO. Complete and fill in the UDP checksum as HW cannot
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* do checksum of UDP packets sent as multiple IP fragments.
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*/
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uh = udp_hdr(skb);
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ipv6h = ipv6_hdr(skb);
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uh->check = 0;
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csum = skb_checksum(skb, 0, skb->len, 0);
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uh->check = udp_v6_check(skb->len, &ipv6h->saddr,
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&ipv6h->daddr, csum);
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if (uh->check == 0)
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uh->check = CSUM_MANGLED_0;
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skb->ip_summed = CHECKSUM_NONE;
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/* If there is no outer header we can fake a checksum offload
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* due to the fact that we have already done the checksum in
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* software prior to segmenting the frame.
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*/
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if (!skb->encap_hdr_csum)
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features |= NETIF_F_HW_CSUM;
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/* Check if there is enough headroom to insert fragment header. */
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tnl_hlen = skb_tnl_header_len(skb);
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if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
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if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
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goto out;
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}
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/* Find the unfragmentable header and shift it left by frag_hdr_sz
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* bytes to insert fragment header.
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*/
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unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
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nexthdr = *prevhdr;
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*prevhdr = NEXTHDR_FRAGMENT;
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unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
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unfrag_ip6hlen + tnl_hlen;
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packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
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memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
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SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
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skb->mac_header -= frag_hdr_sz;
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skb->network_header -= frag_hdr_sz;
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fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
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fptr->nexthdr = nexthdr;
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fptr->reserved = 0;
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if (!skb_shinfo(skb)->ip6_frag_id)
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ipv6_proxy_select_ident(dev_net(skb->dev), skb);
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fptr->identification = skb_shinfo(skb)->ip6_frag_id;
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/* Fragment the skb. ipv6 header and the remaining fields of the
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* fragment header are updated in ipv6_gso_segment()
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*/
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segs = skb_segment(skb, features);
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}
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out:
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return segs;
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}
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static struct sk_buff **udp6_gro_receive(struct sk_buff **head,
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struct sk_buff *skb)
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{
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struct udphdr *uh = udp_gro_udphdr(skb);
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if (unlikely(!uh))
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goto flush;
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/* Don't bother verifying checksum if we're going to flush anyway. */
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if (NAPI_GRO_CB(skb)->flush)
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goto skip;
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if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
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ip6_gro_compute_pseudo))
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goto flush;
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else if (uh->check)
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skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
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ip6_gro_compute_pseudo);
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skip:
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NAPI_GRO_CB(skb)->is_ipv6 = 1;
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return udp_gro_receive(head, skb, uh);
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flush:
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NAPI_GRO_CB(skb)->flush = 1;
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return NULL;
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}
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static int udp6_gro_complete(struct sk_buff *skb, int nhoff)
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{
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const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
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struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
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if (uh->check) {
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skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
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uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
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&ipv6h->daddr, 0);
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} else {
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skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
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}
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return udp_gro_complete(skb, nhoff);
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}
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static const struct net_offload udpv6_offload = {
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.callbacks = {
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.gso_segment = udp6_ufo_fragment,
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.gro_receive = udp6_gro_receive,
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.gro_complete = udp6_gro_complete,
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},
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};
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int __init udp_offload_init(void)
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{
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return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
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}
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