![Willem de Bruijn](/assets/img/avatar_default.png)
Validate gso_type during segmentation as SKB_GSO_DODGY sources
may pass packets where the gso_type does not match the contents.
Syzkaller was able to enter the SCTP gso handler with a packet of
gso_type SKB_GSO_TCPV4.
On entry of transport layer gso handlers, verify that the gso_type
matches the transport protocol.
Fixes: 90017accff
("sctp: Add GSO support")
Link: http://lkml.kernel.org/r/<001a1137452496ffc305617e5fe0@google.com>
Reported-by: syzbot+fee64147a25aecd48055@syzkaller.appspotmail.com
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
175 lines
4.6 KiB
C
175 lines
4.6 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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int err;
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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->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 (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP))
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goto out;
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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_UNNECESSARY;
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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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err = ip6_find_1stfragopt(skb, &prevhdr);
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if (err < 0)
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return ERR_PTR(err);
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unfrag_ip6hlen = err;
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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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fptr->identification = ipv6_proxy_select_ident(dev_net(skb->dev), skb);
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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, udp6_lib_lookup_skb);
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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, udp6_lib_lookup_skb);
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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 udpv6_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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int udpv6_offload_exit(void)
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{
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return inet6_del_offload(&udpv6_offload, IPPROTO_UDP);
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}
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