Merge branch 'skb_checksum_help'

Paul Durrant says:

====================
make skb_checksum_setup generally available

Both xen-netfront and xen-netback need to be able to set up the partial
checksum offset of an skb and may also need to recalculate the pseudo-
header checksum in the process. This functionality is currently private
and duplicated between the two drivers.

Patch #1 of this series moves the implementation into the core network code
as there is nothing xen-specific about it and it is potentially useful to
any network driver.
Patch #2 removes the private implementation from netback.
Patch #3 removes the private implementation from netfront.

v2:
- Put skb_checksum_setup in skbuff.c rather than dev.c
- remove inline
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 6 insertions, 302 deletions

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 27385639b6e5..6b62c3eb8e18 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -39,7 +39,6 @@
 #include <linux/udp.h>
 
 #include <net/tcp.h>
-#include <net/ip6_checksum.h>
 
 #include <xen/xen.h>
 #include <xen/events.h>
@@ -1051,257 +1050,9 @@ static int xenvif_set_skb_gso(struct xenvif *vif,
         return 0;
 }
 
-static inline int maybe_pull_tail(struct sk_buff *skb, unsigned int len,
-                                  unsigned int max)
-{
-        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)
-{
-        unsigned int off;
-        bool fragment;
-        int err;
-
-        fragment = false;
-
-        err = maybe_pull_tail(skb,
-                              sizeof(struct iphdr),
-                              MAX_IP_HDR_LEN);
-        if (err < 0)
-                goto out;
-
-        if (ip_hdr(skb)->frag_off & htons(IP_OFFSET | IP_MF))
-                fragment = true;
-
-        off = ip_hdrlen(skb);
-
-        err = -EPROTO;
-
-        if (fragment)
-                goto out;
-
-        switch (ip_hdr(skb)->protocol) {
-        case IPPROTO_TCP:
-                err = maybe_pull_tail(skb,
-                                      off + sizeof(struct tcphdr),
-                                      MAX_IP_HDR_LEN);
-                if (err < 0)
-                        goto out;
-
-                if (!skb_partial_csum_set(skb, off,
-                                          offsetof(struct tcphdr, check))) {
-                        err = -EPROTO;
-                        goto out;
-                }
-
-                if (recalculate_partial_csum)
-                        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:
-                err = maybe_pull_tail(skb,
-                                      off + sizeof(struct udphdr),
-                                      MAX_IP_HDR_LEN);
-                if (err < 0)
-                        goto out;
-
-                if (!skb_partial_csum_set(skb, off,
-                                          offsetof(struct udphdr, check))) {
-                        err = -EPROTO;
-                        goto out;
-                }
-
-                if (recalculate_partial_csum)
-                        udp_hdr(skb)->check =
-                                ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
-                                                   ip_hdr(skb)->daddr,
-                                                   skb->len - off,
-                                                   IPPROTO_UDP, 0);
-                break;
-        default:
-                goto out;
-        }
-
-        err = 0;
-
-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;
-        u8 nexthdr;
-        unsigned int off;
-        unsigned int len;
-        bool fragment;
-        bool done;
-
-        fragment = false;
-        done = false;
-
-        off = sizeof(struct ipv6hdr);
-
-        err = maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
-        if (err < 0)
-                goto out;
-
-        nexthdr = ipv6_hdr(skb)->nexthdr;
-
-        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;
-
-                        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;
-
-                        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;
-
-                        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 += sizeof(struct frag_hdr);
-                        break;
-                }
-                default:
-                        done = true;
-                        break;
-                }
-        }
-
-        err = -EPROTO;
-
-        if (!done || fragment)
-                goto out;
-
-        switch (nexthdr) {
-        case IPPROTO_TCP:
-                err = maybe_pull_tail(skb,
-                                      off + sizeof(struct tcphdr),
-                                      MAX_IPV6_HDR_LEN);
-                if (err < 0)
-                        goto out;
-
-                if (!skb_partial_csum_set(skb, off,
-                                          offsetof(struct tcphdr, check))) {
-                        err = -EPROTO;
-                        goto out;
-                }
-
-                if (recalculate_partial_csum)
-                        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:
-                err = maybe_pull_tail(skb,
-                                      off + sizeof(struct udphdr),
-                                      MAX_IPV6_HDR_LEN);
-                if (err < 0)
-                        goto out;
-
-                if (!skb_partial_csum_set(skb, off,
-                                          offsetof(struct udphdr, check))) {
-                        err = -EPROTO;
-                        goto out;
-                }
-
-                if (recalculate_partial_csum)
-                        udp_hdr(skb)->check =
-                                ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
-                                                 &ipv6_hdr(skb)->daddr,
-                                                 skb->len - off,
-                                                 IPPROTO_UDP, 0);
-                break;
-        default:
-                goto out;
-        }
-
-        err = 0;
-
-out:
-        return err;
-}
-
 static int checksum_setup(struct xenvif *vif, struct sk_buff *skb)
 {
-        int err = -EPROTO;
-        int recalculate_partial_csum = 0;
+        bool recalculate_partial_csum = false;
 
         /* A GSO SKB must be CHECKSUM_PARTIAL. However some buggy
          * peers can fail to set NETRXF_csum_blank when sending a GSO
@@ -1311,19 +1062,14 @@ static int checksum_setup(struct xenvif *vif, struct sk_buff *skb)
         if (skb->ip_summed != CHECKSUM_PARTIAL && skb_is_gso(skb)) {
                 vif->rx_gso_checksum_fixup++;
                 skb->ip_summed = CHECKSUM_PARTIAL;
-                recalculate_partial_csum = 1;
+                recalculate_partial_csum = true;
         }
 
         /* A non-CHECKSUM_PARTIAL SKB does not require setup. */
         if (skb->ip_summed != CHECKSUM_PARTIAL)
                 return 0;
 
-        if (skb->protocol == htons(ETH_P_IP))
-                err = checksum_setup_ip(vif, skb, recalculate_partial_csum);
-        else if (skb->protocol == htons(ETH_P_IPV6))
-                err = checksum_setup_ipv6(vif, skb, recalculate_partial_csum);
-
-        return err;
+        return skb_checksum_setup(skb, recalculate_partial_csum);
 }
 
 static bool tx_credit_exceeded(struct xenvif *vif, unsigned size)
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index e59acb1daa23..c41537b577a4 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -859,9 +859,7 @@ static RING_IDX xennet_fill_frags(struct netfront_info *np,
 
 static int checksum_setup(struct net_device *dev, struct sk_buff *skb)
 {
-        struct iphdr *iph;
-        int err = -EPROTO;
-        int recalculate_partial_csum = 0;
+        bool recalculate_partial_csum = false;
 
         /*
          * A GSO SKB must be CHECKSUM_PARTIAL. However some buggy
@@ -873,54 +871,14 @@ static int checksum_setup(struct net_device *dev, struct sk_buff *skb)
                 struct netfront_info *np = netdev_priv(dev);
                 np->rx_gso_checksum_fixup++;
                 skb->ip_summed = CHECKSUM_PARTIAL;
-                recalculate_partial_csum = 1;
+                recalculate_partial_csum = true;
         }
 
         /* A non-CHECKSUM_PARTIAL SKB does not require setup. */
         if (skb->ip_summed != CHECKSUM_PARTIAL)
                 return 0;
 
-        if (skb->protocol != htons(ETH_P_IP))
-                goto out;
-
-        iph = (void *)skb->data;
-
-        switch (iph->protocol) {
-        case IPPROTO_TCP:
-                if (!skb_partial_csum_set(skb, 4 * iph->ihl,
-                                          offsetof(struct tcphdr, check)))
-                        goto out;
-
-                if (recalculate_partial_csum) {
-                        struct tcphdr *tcph = tcp_hdr(skb);
-                        tcph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
-                                                         skb->len - iph->ihl*4,
-                                                         IPPROTO_TCP, 0);
-                }
-                break;
-        case IPPROTO_UDP:
-                if (!skb_partial_csum_set(skb, 4 * iph->ihl,
-                                          offsetof(struct udphdr, check)))
-                        goto out;
-
-                if (recalculate_partial_csum) {
-                        struct udphdr *udph = udp_hdr(skb);
-                        udph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
-                                                         skb->len - iph->ihl*4,
-                                                         IPPROTO_UDP, 0);
-                }
-                break;
-        default:
-                if (net_ratelimit())
-                        pr_err("Attempting to checksum a non-TCP/UDP packet, dropping a protocol %d packet\n",
-                               iph->protocol);
-                goto out;
-        }
-
-        err = 0;
-
-out:
-        return err;
+        return skb_checksum_setup(skb, recalculate_partial_csum);
 }
 
 static int handle_incoming_queue(struct net_device *dev,