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xen-netback: fix fragment detection in checksum setup
The code to detect fragments in checksum_setup() was missing for IPv4 and too eager for IPv6. (It transpires that Windows seems to send IPv6 packets with a fragment header even if they are not a fragment - i.e. offset is zero, and M bit is not set). This patch also incorporates a fix to callers of maybe_pull_tail() where skb->network_header was being erroneously added to the length argument. Signed-off-by: Paul Durrant <paul.durrant@citrix.com> Signed-off-by: Zoltan Kiss <zoltan.kiss@citrix.com> Cc: Wei Liu <wei.liu2@citrix.com> Cc: Ian Campbell <ian.campbell@citrix.com> Cc: David Vrabel <david.vrabel@citrix.com> cc: David Miller <davem@davemloft.net> Acked-by: Wei Liu <wei.liu2@citrix.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paul Durrant
David S. Miller
parent
df48ada4f8
commit
1431fb31ec
3 changed files with 136 additions and 96 deletions
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@ -1149,49 +1149,72 @@ static int xenvif_set_skb_gso(struct xenvif *vif,
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return 0;
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}
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static inline void maybe_pull_tail(struct sk_buff *skb, unsigned int len)
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static inline int maybe_pull_tail(struct sk_buff *skb, unsigned int len,
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unsigned int max)
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{
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if (skb_is_nonlinear(skb) && skb_headlen(skb) < len) {
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/* If we need to pullup then pullup to the max, so we
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* won't need to do it again.
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*/
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int target = min_t(int, skb->len, MAX_TCP_HEADER);
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__pskb_pull_tail(skb, target - skb_headlen(skb));
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}
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if (skb_headlen(skb) >= len)
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return 0;
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/* If we need to pullup then pullup to the max, so we
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* won't need to do it again.
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*/
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if (max > skb->len)
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max = skb->len;
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if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
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return -ENOMEM;
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if (skb_headlen(skb) < len)
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return -EPROTO;
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return 0;
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}
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/* This value should be large enough to cover a tagged ethernet header plus
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* maximally sized IP and TCP or UDP headers.
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*/
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#define MAX_IP_HDR_LEN 128
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static int checksum_setup_ip(struct xenvif *vif, struct sk_buff *skb,
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int recalculate_partial_csum)
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{
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struct iphdr *iph = (void *)skb->data;
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unsigned int header_size;
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unsigned int off;
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int err = -EPROTO;
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bool fragment;
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int err;
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off = sizeof(struct iphdr);
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fragment = false;
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header_size = skb->network_header + off + MAX_IPOPTLEN;
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maybe_pull_tail(skb, header_size);
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err = maybe_pull_tail(skb,
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sizeof(struct iphdr),
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MAX_IP_HDR_LEN);
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if (err < 0)
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goto out;
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off = iph->ihl * 4;
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if (ip_hdr(skb)->frag_off & htons(IP_OFFSET | IP_MF))
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fragment = true;
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switch (iph->protocol) {
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off = ip_hdrlen(skb);
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err = -EPROTO;
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switch (ip_hdr(skb)->protocol) {
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case IPPROTO_TCP:
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if (!skb_partial_csum_set(skb, off,
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offsetof(struct tcphdr, check)))
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goto out;
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if (recalculate_partial_csum) {
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struct tcphdr *tcph = tcp_hdr(skb);
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err = maybe_pull_tail(skb,
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off + sizeof(struct tcphdr),
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MAX_IP_HDR_LEN);
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if (err < 0)
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goto out;
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header_size = skb->network_header +
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off +
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sizeof(struct tcphdr);
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maybe_pull_tail(skb, header_size);
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tcph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
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skb->len - off,
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IPPROTO_TCP, 0);
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tcp_hdr(skb)->check =
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~csum_tcpudp_magic(ip_hdr(skb)->saddr,
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ip_hdr(skb)->daddr,
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skb->len - off,
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IPPROTO_TCP, 0);
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}
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break;
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case IPPROTO_UDP:
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@ -1200,24 +1223,20 @@ static int checksum_setup_ip(struct xenvif *vif, struct sk_buff *skb,
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goto out;
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if (recalculate_partial_csum) {
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struct udphdr *udph = udp_hdr(skb);
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err = maybe_pull_tail(skb,
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off + sizeof(struct udphdr),
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MAX_IP_HDR_LEN);
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if (err < 0)
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goto out;
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header_size = skb->network_header +
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off +
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sizeof(struct udphdr);
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maybe_pull_tail(skb, header_size);
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udph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
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skb->len - off,
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IPPROTO_UDP, 0);
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udp_hdr(skb)->check =
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~csum_tcpudp_magic(ip_hdr(skb)->saddr,
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ip_hdr(skb)->daddr,
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skb->len - off,
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IPPROTO_UDP, 0);
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}
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break;
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default:
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if (net_ratelimit())
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netdev_err(vif->dev,
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"Attempting to checksum a non-TCP/UDP packet, "
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"dropping a protocol %d packet\n",
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iph->protocol);
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goto out;
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}
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@ -1227,75 +1246,99 @@ static int checksum_setup_ip(struct xenvif *vif, struct sk_buff *skb,
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return err;
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}
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/* This value should be large enough to cover a tagged ethernet header plus
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* an IPv6 header, all options, and a maximal TCP or UDP header.
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*/
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#define MAX_IPV6_HDR_LEN 256
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#define OPT_HDR(type, skb, off) \
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(type *)(skb_network_header(skb) + (off))
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static int checksum_setup_ipv6(struct xenvif *vif, struct sk_buff *skb,
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int recalculate_partial_csum)
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{
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int err = -EPROTO;
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struct ipv6hdr *ipv6h = (void *)skb->data;
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int err;
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u8 nexthdr;
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unsigned int header_size;
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unsigned int off;
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unsigned int len;
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bool fragment;
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bool done;
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fragment = false;
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done = false;
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off = sizeof(struct ipv6hdr);
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header_size = skb->network_header + off;
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maybe_pull_tail(skb, header_size);
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err = maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
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if (err < 0)
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goto out;
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nexthdr = ipv6h->nexthdr;
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nexthdr = ipv6_hdr(skb)->nexthdr;
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while ((off <= sizeof(struct ipv6hdr) + ntohs(ipv6h->payload_len)) &&
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!done) {
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len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
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while (off <= len && !done) {
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switch (nexthdr) {
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case IPPROTO_DSTOPTS:
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case IPPROTO_HOPOPTS:
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case IPPROTO_ROUTING: {
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struct ipv6_opt_hdr *hp = (void *)(skb->data + off);
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struct ipv6_opt_hdr *hp;
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header_size = skb->network_header +
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off +
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sizeof(struct ipv6_opt_hdr);
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maybe_pull_tail(skb, header_size);
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err = maybe_pull_tail(skb,
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off +
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sizeof(struct ipv6_opt_hdr),
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MAX_IPV6_HDR_LEN);
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if (err < 0)
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goto out;
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hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
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nexthdr = hp->nexthdr;
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off += ipv6_optlen(hp);
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break;
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}
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case IPPROTO_AH: {
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struct ip_auth_hdr *hp = (void *)(skb->data + off);
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struct ip_auth_hdr *hp;
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header_size = skb->network_header +
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off +
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sizeof(struct ip_auth_hdr);
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maybe_pull_tail(skb, header_size);
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err = maybe_pull_tail(skb,
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off +
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sizeof(struct ip_auth_hdr),
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MAX_IPV6_HDR_LEN);
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if (err < 0)
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goto out;
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hp = OPT_HDR(struct ip_auth_hdr, skb, off);
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nexthdr = hp->nexthdr;
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off += (hp->hdrlen+2)<<2;
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off += ipv6_authlen(hp);
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break;
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}
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case IPPROTO_FRAGMENT: {
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struct frag_hdr *hp;
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err = maybe_pull_tail(skb,
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off +
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sizeof(struct frag_hdr),
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MAX_IPV6_HDR_LEN);
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if (err < 0)
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goto out;
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hp = OPT_HDR(struct frag_hdr, skb, off);
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if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
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fragment = true;
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nexthdr = hp->nexthdr;
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off += sizeof(struct frag_hdr);
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break;
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}
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case IPPROTO_FRAGMENT:
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fragment = true;
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/* fall through */
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default:
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done = true;
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break;
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}
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}
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if (!done) {
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if (net_ratelimit())
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netdev_err(vif->dev, "Failed to parse packet header\n");
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goto out;
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}
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err = -EPROTO;
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if (fragment) {
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if (net_ratelimit())
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netdev_err(vif->dev, "Packet is a fragment!\n");
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if (!done || fragment)
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goto out;
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}
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switch (nexthdr) {
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case IPPROTO_TCP:
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@ -1304,17 +1347,17 @@ static int checksum_setup_ipv6(struct xenvif *vif, struct sk_buff *skb,
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goto out;
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if (recalculate_partial_csum) {
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struct tcphdr *tcph = tcp_hdr(skb);
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err = maybe_pull_tail(skb,
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off + sizeof(struct tcphdr),
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MAX_IPV6_HDR_LEN);
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if (err < 0)
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goto out;
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header_size = skb->network_header +
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off +
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sizeof(struct tcphdr);
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maybe_pull_tail(skb, header_size);
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tcph->check = ~csum_ipv6_magic(&ipv6h->saddr,
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&ipv6h->daddr,
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skb->len - off,
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IPPROTO_TCP, 0);
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tcp_hdr(skb)->check =
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~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
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&ipv6_hdr(skb)->daddr,
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skb->len - off,
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IPPROTO_TCP, 0);
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}
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break;
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case IPPROTO_UDP:
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@ -1323,25 +1366,20 @@ static int checksum_setup_ipv6(struct xenvif *vif, struct sk_buff *skb,
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goto out;
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if (recalculate_partial_csum) {
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struct udphdr *udph = udp_hdr(skb);
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err = maybe_pull_tail(skb,
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off + sizeof(struct udphdr),
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MAX_IPV6_HDR_LEN);
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if (err < 0)
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goto out;
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header_size = skb->network_header +
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off +
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sizeof(struct udphdr);
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maybe_pull_tail(skb, header_size);
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udph->check = ~csum_ipv6_magic(&ipv6h->saddr,
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&ipv6h->daddr,
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skb->len - off,
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IPPROTO_UDP, 0);
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udp_hdr(skb)->check =
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~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
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&ipv6_hdr(skb)->daddr,
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skb->len - off,
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IPPROTO_UDP, 0);
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}
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break;
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default:
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if (net_ratelimit())
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netdev_err(vif->dev,
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"Attempting to checksum a non-TCP/UDP packet, "
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"dropping a protocol %d packet\n",
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nexthdr);
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goto out;
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}
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@ -4,6 +4,7 @@
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#include <uapi/linux/ipv6.h>
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#define ipv6_optlen(p) (((p)->hdrlen+1) << 3)
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#define ipv6_authlen(p) (((p)->hdrlen+2) << 2)
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/*
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* This structure contains configuration options per IPv6 link.
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*/
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@ -110,7 +110,8 @@ struct frag_hdr {
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__be32 identification;
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};
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#define IP6_MF 0x0001
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#define IP6_MF 0x0001
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#define IP6_OFFSET 0xFFF8
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#include <net/sock.h>
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