3 files changed, 140 insertions, 100 deletions

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 64f0e0d18b81..acf13920e6d1 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -1149,49 +1149,72 @@ static int xenvif_set_skb_gso(struct xenvif *vif,
         return 0;
 }
 
-static inline void maybe_pull_tail(struct sk_buff *skb, unsigned int len)
+static inline int maybe_pull_tail(struct sk_buff *skb, unsigned int len,
+                                  unsigned int max)
 {
-        if (skb_is_nonlinear(skb) && skb_headlen(skb) < len) {
-                /* If we need to pullup then pullup to the max, so we
-                 * won't need to do it again.
-                 */
-                int target = min_t(int, skb->len, MAX_TCP_HEADER);
-                __pskb_pull_tail(skb, target - skb_headlen(skb));
-        }
+        if (skb_headlen(skb) >= len)
+                return 0;
+
+        /* If we need to pullup then pullup to the max, so we
+         * won't need to do it again.
+         */
+        if (max > skb->len)
+                max = skb->len;
+
+        if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
+                return -ENOMEM;
+
+        if (skb_headlen(skb) < len)
+                return -EPROTO;
+
+        return 0;
 }
 
+/* This value should be large enough to cover a tagged ethernet header plus
+ * maximally sized IP and TCP or UDP headers.
+ */
+#define MAX_IP_HDR_LEN 128
+
 static int checksum_setup_ip(struct xenvif *vif, struct sk_buff *skb,
                              int recalculate_partial_csum)
 {
-        struct iphdr *iph = (void *)skb->data;
-        unsigned int header_size;
         unsigned int off;
-        int err = -EPROTO;
+        bool fragment;
+        int err;
+
+        fragment = false;
+
+        err = maybe_pull_tail(skb,
+                              sizeof(struct iphdr),
+                              MAX_IP_HDR_LEN);
+        if (err < 0)
+                goto out;
 
-        off = sizeof(struct iphdr);
+        if (ip_hdr(skb)->frag_off & htons(IP_OFFSET | IP_MF))
+                fragment = true;
 
-        header_size = skb->network_header + off + MAX_IPOPTLEN;
-        maybe_pull_tail(skb, header_size);
+        off = ip_hdrlen(skb);
 
-        off = iph->ihl * 4;
+        err = -EPROTO;
 
-        switch (iph->protocol) {
+        switch (ip_hdr(skb)->protocol) {
         case IPPROTO_TCP:
                 if (!skb_partial_csum_set(skb, off,
                                           offsetof(struct tcphdr, check)))
                         goto out;
 
                 if (recalculate_partial_csum) {
-                        struct tcphdr *tcph = tcp_hdr(skb);
-
-                        header_size = skb->network_header +
-                                off +
-                                sizeof(struct tcphdr);
-                        maybe_pull_tail(skb, header_size);
-
-                        tcph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
-                                                         skb->len - off,
-                                                         IPPROTO_TCP, 0);
+                        err = maybe_pull_tail(skb,
+                                              off + sizeof(struct tcphdr),
+                                              MAX_IP_HDR_LEN);
+                        if (err < 0)
+                                goto out;
+
+                        tcp_hdr(skb)->check =
+                                ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
+                                                   ip_hdr(skb)->daddr,
+                                                   skb->len - off,
+                                                   IPPROTO_TCP, 0);
                 }
                 break;
         case IPPROTO_UDP:
@@ -1200,24 +1223,20 @@ static int checksum_setup_ip(struct xenvif *vif, struct sk_buff *skb,
                         goto out;
 
                 if (recalculate_partial_csum) {
-                        struct udphdr *udph = udp_hdr(skb);
-
-                        header_size = skb->network_header +
-                                off +
-                                sizeof(struct udphdr);
-                        maybe_pull_tail(skb, header_size);
-
-                        udph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
-                                                         skb->len - off,
-                                                         IPPROTO_UDP, 0);
+                        err = maybe_pull_tail(skb,
+                                              off + sizeof(struct udphdr),
+                                              MAX_IP_HDR_LEN);
+                        if (err < 0)
+                                goto out;
+
+                        udp_hdr(skb)->check =
+                                ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
+                                                   ip_hdr(skb)->daddr,
+                                                   skb->len - off,
+                                                   IPPROTO_UDP, 0);
                 }
                 break;
         default:
-                if (net_ratelimit())
-                        netdev_err(vif->dev,
-                                   "Attempting to checksum a non-TCP/UDP packet, "
-                                   "dropping a protocol %d packet\n",
-                                   iph->protocol);
                 goto out;
         }
 
@@ -1227,75 +1246,99 @@ out:
         return err;
 }
 
+/* This value should be large enough to cover a tagged ethernet header plus
+ * an IPv6 header, all options, and a maximal TCP or UDP header.
+ */
+#define MAX_IPV6_HDR_LEN 256
+
+#define OPT_HDR(type, skb, off) \
+        (type *)(skb_network_header(skb) + (off))
+
 static int checksum_setup_ipv6(struct xenvif *vif, struct sk_buff *skb,
                                int recalculate_partial_csum)
 {
-        int err = -EPROTO;
-        struct ipv6hdr *ipv6h = (void *)skb->data;
+        int err;
         u8 nexthdr;
-        unsigned int header_size;
         unsigned int off;
+        unsigned int len;
         bool fragment;
         bool done;
 
+        fragment = false;
         done = false;
 
         off = sizeof(struct ipv6hdr);
 
-        header_size = skb->network_header + off;
-        maybe_pull_tail(skb, header_size);
+        err = maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
+        if (err < 0)
+                goto out;
 
-        nexthdr = ipv6h->nexthdr;
+        nexthdr = ipv6_hdr(skb)->nexthdr;
 
-        while ((off <= sizeof(struct ipv6hdr) + ntohs(ipv6h->payload_len)) &&
-               !done) {
+        len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
+        while (off <= len && !done) {
                 switch (nexthdr) {
                 case IPPROTO_DSTOPTS:
                 case IPPROTO_HOPOPTS:
                 case IPPROTO_ROUTING: {
-                        struct ipv6_opt_hdr *hp = (void *)(skb->data + off);
+                        struct ipv6_opt_hdr *hp;
 
-                        header_size = skb->network_header +
-                                off +
-                                sizeof(struct ipv6_opt_hdr);
-                        maybe_pull_tail(skb, header_size);
+                        err = maybe_pull_tail(skb,
+                                              off +
+                                              sizeof(struct ipv6_opt_hdr),
+                                              MAX_IPV6_HDR_LEN);
+                        if (err < 0)
+                                goto out;
 
+                        hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
                         nexthdr = hp->nexthdr;
                         off += ipv6_optlen(hp);
                         break;
                 }
                 case IPPROTO_AH: {
-                        struct ip_auth_hdr *hp = (void *)(skb->data + off);
+                        struct ip_auth_hdr *hp;
+
+                        err = maybe_pull_tail(skb,
+                                              off +
+                                              sizeof(struct ip_auth_hdr),
+                                              MAX_IPV6_HDR_LEN);
+                        if (err < 0)
+                                goto out;
+
+                        hp = OPT_HDR(struct ip_auth_hdr, skb, off);
+                        nexthdr = hp->nexthdr;
+                        off += ipv6_authlen(hp);
+                        break;
+                }
+                case IPPROTO_FRAGMENT: {
+                        struct frag_hdr *hp;
 
-                        header_size = skb->network_header +
-                                off +
-                                sizeof(struct ip_auth_hdr);
-                        maybe_pull_tail(skb, header_size);
+                        err = maybe_pull_tail(skb,
+                                              off +
+                                              sizeof(struct frag_hdr),
+                                              MAX_IPV6_HDR_LEN);
+                        if (err < 0)
+                                goto out;
+
+                        hp = OPT_HDR(struct frag_hdr, skb, off);
+
+                        if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
+                                fragment = true;
 
                         nexthdr = hp->nexthdr;
-                        off += (hp->hdrlen+2)<<2;
+                        off += sizeof(struct frag_hdr);
                         break;
                 }
-                case IPPROTO_FRAGMENT:
-                        fragment = true;
-                        /* fall through */
                 default:
                         done = true;
                         break;
                 }
         }
 
-        if (!done) {
-                if (net_ratelimit())
-                        netdev_err(vif->dev, "Failed to parse packet header\n");
-                goto out;
-        }
+        err = -EPROTO;
 
-        if (fragment) {
-                if (net_ratelimit())
-                        netdev_err(vif->dev, "Packet is a fragment!\n");
+        if (!done || fragment)
                 goto out;
-        }
 
         switch (nexthdr) {
         case IPPROTO_TCP:
@@ -1304,17 +1347,17 @@ static int checksum_setup_ipv6(struct xenvif *vif, struct sk_buff *skb,
                         goto out;
 
                 if (recalculate_partial_csum) {
-                        struct tcphdr *tcph = tcp_hdr(skb);
-
-                        header_size = skb->network_header +
-                                off +
-                                sizeof(struct tcphdr);
-                        maybe_pull_tail(skb, header_size);
-
-                        tcph->check = ~csum_ipv6_magic(&ipv6h->saddr,
-                                                       &ipv6h->daddr,
-                                                       skb->len - off,
-                                                       IPPROTO_TCP, 0);
+                        err = maybe_pull_tail(skb,
+                                              off + sizeof(struct tcphdr),
+                                              MAX_IPV6_HDR_LEN);
+                        if (err < 0)
+                                goto out;
+
+                        tcp_hdr(skb)->check =
+                                ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
+                                                 &ipv6_hdr(skb)->daddr,
+                                                 skb->len - off,
+                                                 IPPROTO_TCP, 0);
                 }
                 break;
         case IPPROTO_UDP:
@@ -1323,25 +1366,20 @@ static int checksum_setup_ipv6(struct xenvif *vif, struct sk_buff *skb,
                         goto out;
 
                 if (recalculate_partial_csum) {
-                        struct udphdr *udph = udp_hdr(skb);
-
-                        header_size = skb->network_header +
-                                off +
-                                sizeof(struct udphdr);
-                        maybe_pull_tail(skb, header_size);
-
-                        udph->check = ~csum_ipv6_magic(&ipv6h->saddr,
-                                                       &ipv6h->daddr,
-                                                       skb->len - off,
-                                                       IPPROTO_UDP, 0);
+                        err = maybe_pull_tail(skb,
+                                              off + sizeof(struct udphdr),
+                                              MAX_IPV6_HDR_LEN);
+                        if (err < 0)
+                                goto out;
+
+                        udp_hdr(skb)->check =
+                                ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
+                                                 &ipv6_hdr(skb)->daddr,
+                                                 skb->len - off,
+                                                 IPPROTO_UDP, 0);
                 }
                 break;
         default:
-                if (net_ratelimit())
-                        netdev_err(vif->dev,
-                                   "Attempting to checksum a non-TCP/UDP packet, "
-                                   "dropping a protocol %d packet\n",
-                                   nexthdr);
                 goto out;
         }
 
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 5d89d1b808a6..c56c350324e4 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -4,6 +4,7 @@
 #include <uapi/linux/ipv6.h>
 
 #define ipv6_optlen(p)  (((p)->hdrlen+1) << 3)
+#define ipv6_authlen(p) (((p)->hdrlen+2) << 2)
 /*
  * This structure contains configuration options per IPv6 link.
  */
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index eb198acaac1d..488316e339a1 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -110,7 +110,8 @@ struct frag_hdr {
         __be32  identification;
 };
 
-#define IP6_MF  0x0001
+#define IP6_MF          0x0001
+#define IP6_OFFSET      0xFFF8
 
 #include <net/sock.h>