net_sched: cls_flow: use skb_header_pointer()

Dan Siemon would like to add tunnelling support to cls_flow

This preliminary patch introduces use of skb_header_pointer() to help
this task, while avoiding skb head reallocation because of deep packet
inspection.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/cls_flow.c b/net/sched/cls_flow.c
index 6994214..9e087d8 100644 (file)
--- a/net/sched/cls_flow.c
+++ b/net/sched/cls_flow.c
@@ -65,132 +65,134 @@ static inline u32 addr_fold(void *addr)
        return (a & 0xFFFFFFFF) ^ (BITS_PER_LONG > 32 ? a >> 32 : 0);
 }
 
-static u32 flow_get_src(struct sk_buff *skb)
+static u32 flow_get_src(const struct sk_buff *skb, int nhoff)
 {
+       __be32 *data = NULL, hdata;
+
        switch (skb->protocol) {
        case htons(ETH_P_IP):
-               if (pskb_network_may_pull(skb, sizeof(struct iphdr)))
-                       return ntohl(ip_hdr(skb)->saddr);
+               data = skb_header_pointer(skb,
+                                         nhoff + offsetof(struct iphdr,
+                                                          saddr),
+                                         4, &hdata);
                break;
        case htons(ETH_P_IPV6):
-               if (pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))
-                       return ntohl(ipv6_hdr(skb)->saddr.s6_addr32[3]);
+               data = skb_header_pointer(skb,
+                                        nhoff + offsetof(struct ipv6hdr,
+                                                         saddr.s6_addr32[3]),
+                                        4, &hdata);
                break;
        }
 
+       if (data)
+               return ntohl(*data);
        return addr_fold(skb->sk);
 }
 
-static u32 flow_get_dst(struct sk_buff *skb)
+static u32 flow_get_dst(const struct sk_buff *skb, int nhoff)
 {
+       __be32 *data = NULL, hdata;
+
        switch (skb->protocol) {
        case htons(ETH_P_IP):
-               if (pskb_network_may_pull(skb, sizeof(struct iphdr)))
-                       return ntohl(ip_hdr(skb)->daddr);
+               data = skb_header_pointer(skb,
+                                         nhoff + offsetof(struct iphdr,
+                                                          daddr),
+                                         4, &hdata);
                break;
        case htons(ETH_P_IPV6):
-               if (pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))
-                       return ntohl(ipv6_hdr(skb)->daddr.s6_addr32[3]);
+               data = skb_header_pointer(skb,
+                                        nhoff + offsetof(struct ipv6hdr,
+                                                         daddr.s6_addr32[3]),
+                                        4, &hdata);
                break;
        }
 
+       if (data)
+               return ntohl(*data);
        return addr_fold(skb_dst(skb)) ^ (__force u16)skb->protocol;
 }
 
-static u32 flow_get_proto(struct sk_buff *skb)
+static u32 flow_get_proto(const struct sk_buff *skb, int nhoff)
 {
+       __u8 *data = NULL, hdata;
+
        switch (skb->protocol) {
        case htons(ETH_P_IP):
-               return pskb_network_may_pull(skb, sizeof(struct iphdr)) ?
-                      ip_hdr(skb)->protocol : 0;
+               data = skb_header_pointer(skb,
+                                         nhoff + offsetof(struct iphdr,
+                                                          protocol),
+                                         1, &hdata);
+               break;
        case htons(ETH_P_IPV6):
-               return pskb_network_may_pull(skb, sizeof(struct ipv6hdr)) ?
-                      ipv6_hdr(skb)->nexthdr : 0;
-       default:
-               return 0;
+               data = skb_header_pointer(skb,
+                                        nhoff + offsetof(struct ipv6hdr,
+                                                         nexthdr),
+                                        1, &hdata);
+               break;
        }
+       if (data)
+               return *data;
+       return 0;
 }
 
-static u32 flow_get_proto_src(struct sk_buff *skb)
+/* helper function to get either src or dst port */
+static __be16 *flow_get_proto_common(const struct sk_buff *skb, int nhoff,
+                                    __be16 *_port, int dst)
 {
+       __be16 *port = NULL;
+       int poff;
+
        switch (skb->protocol) {
        case htons(ETH_P_IP): {
-               struct iphdr *iph;
-               int poff;
+               struct iphdr *iph, _iph;
 
-               if (!pskb_network_may_pull(skb, sizeof(*iph)))
+               iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
+               if (!iph)
                        break;
-               iph = ip_hdr(skb);
                if (ip_is_fragment(iph))
                        break;
                poff = proto_ports_offset(iph->protocol);
-               if (poff >= 0 &&
-                   pskb_network_may_pull(skb, iph->ihl * 4 + 2 + poff)) {
-                       iph = ip_hdr(skb);
-                       return ntohs(*(__be16 *)((void *)iph + iph->ihl * 4 +
-                                                poff));
-               }
+               if (poff >= 0)
+                       port = skb_header_pointer(skb,
+                                       nhoff + iph->ihl * 4 + poff + dst,
+                                       sizeof(*_port), _port);
                break;
        }
        case htons(ETH_P_IPV6): {
-               struct ipv6hdr *iph;
-               int poff;
+               struct ipv6hdr *iph, _iph;
 
-               if (!pskb_network_may_pull(skb, sizeof(*iph)))
+               iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
+               if (!iph)
                        break;
-               iph = ipv6_hdr(skb);
                poff = proto_ports_offset(iph->nexthdr);
-               if (poff >= 0 &&
-                   pskb_network_may_pull(skb, sizeof(*iph) + poff + 2)) {
-                       iph = ipv6_hdr(skb);
-                       return ntohs(*(__be16 *)((void *)iph + sizeof(*iph) +
-                                                poff));
-               }
+               if (poff >= 0)
+                       port = skb_header_pointer(skb,
+                                       nhoff + sizeof(*iph) + poff + dst,
+                                       sizeof(*_port), _port);
                break;
        }
        }
 
-       return addr_fold(skb->sk);
+       return port;
 }
 
-static u32 flow_get_proto_dst(struct sk_buff *skb)
+static u32 flow_get_proto_src(const struct sk_buff *skb, int nhoff)
 {
-       switch (skb->protocol) {
-       case htons(ETH_P_IP): {
-               struct iphdr *iph;
-               int poff;
+       __be16 _port, *port = flow_get_proto_common(skb, nhoff, &_port, 0);
 
-               if (!pskb_network_may_pull(skb, sizeof(*iph)))
-                       break;
-               iph = ip_hdr(skb);
-               if (ip_is_fragment(iph))
-                       break;
-               poff = proto_ports_offset(iph->protocol);
-               if (poff >= 0 &&
-                   pskb_network_may_pull(skb, iph->ihl * 4 + 4 + poff)) {
-                       iph = ip_hdr(skb);
-                       return ntohs(*(__be16 *)((void *)iph + iph->ihl * 4 +
-                                                2 + poff));
-               }
-               break;
-       }
-       case htons(ETH_P_IPV6): {
-               struct ipv6hdr *iph;
-               int poff;
+       if (port)
+               return ntohs(*port);
 
-               if (!pskb_network_may_pull(skb, sizeof(*iph)))
-                       break;
-               iph = ipv6_hdr(skb);
-               poff = proto_ports_offset(iph->nexthdr);
-               if (poff >= 0 &&
-                   pskb_network_may_pull(skb, sizeof(*iph) + poff + 4)) {
-                       iph = ipv6_hdr(skb);
-                       return ntohs(*(__be16 *)((void *)iph + sizeof(*iph) +
-                                                poff + 2));
-               }
-               break;
-       }
-       }
+       return addr_fold(skb->sk);
+}
+
+static u32 flow_get_proto_dst(const struct sk_buff *skb, int nhoff)
+{
+       __be16 _port, *port = flow_get_proto_common(skb, nhoff, &_port, 2);
+
+       if (port)
+               return ntohs(*port);
 
        return addr_fold(skb_dst(skb)) ^ (__force u16)skb->protocol;
 }
@@ -223,7 +225,7 @@ static u32 flow_get_nfct(const struct sk_buff *skb)
 #define CTTUPLE(skb, member)                                           \
 ({                                                                     \
        enum ip_conntrack_info ctinfo;                                  \
-       struct nf_conn *ct = nf_ct_get(skb, &ctinfo);                   \
+       const struct nf_conn *ct = nf_ct_get(skb, &ctinfo);             \
        if (ct == NULL)                                                 \
                goto fallback;                                          \
        ct->tuplehash[CTINFO2DIR(ctinfo)].tuple.member;                 \
@@ -236,7 +238,7 @@ static u32 flow_get_nfct(const struct sk_buff *skb)
 })
 #endif
 
-static u32 flow_get_nfct_src(struct sk_buff *skb)
+static u32 flow_get_nfct_src(const struct sk_buff *skb, int nhoff)
 {
        switch (skb->protocol) {
        case htons(ETH_P_IP):
@@ -245,10 +247,10 @@ static u32 flow_get_nfct_src(struct sk_buff *skb)
                return ntohl(CTTUPLE(skb, src.u3.ip6[3]));
        }
 fallback:
-       return flow_get_src(skb);
+       return flow_get_src(skb, nhoff);
 }
 
-static u32 flow_get_nfct_dst(struct sk_buff *skb)
+static u32 flow_get_nfct_dst(const struct sk_buff *skb, int nhoff)
 {
        switch (skb->protocol) {
        case htons(ETH_P_IP):
@@ -257,21 +259,21 @@ static u32 flow_get_nfct_dst(struct sk_buff *skb)
                return ntohl(CTTUPLE(skb, dst.u3.ip6[3]));
        }
 fallback:
-       return flow_get_dst(skb);
+       return flow_get_dst(skb, nhoff);
 }
 
-static u32 flow_get_nfct_proto_src(struct sk_buff *skb)
+static u32 flow_get_nfct_proto_src(const struct sk_buff *skb, int nhoff)
 {
        return ntohs(CTTUPLE(skb, src.u.all));
 fallback:
-       return flow_get_proto_src(skb);
+       return flow_get_proto_src(skb, nhoff);
 }
 
-static u32 flow_get_nfct_proto_dst(struct sk_buff *skb)
+static u32 flow_get_nfct_proto_dst(const struct sk_buff *skb, int nhoff)
 {
        return ntohs(CTTUPLE(skb, dst.u.all));
 fallback:
-       return flow_get_proto_dst(skb);
+       return flow_get_proto_dst(skb, nhoff);
 }
 
 static u32 flow_get_rtclassid(const struct sk_buff *skb)
@@ -313,17 +315,19 @@ static u32 flow_get_rxhash(struct sk_buff *skb)
 
 static u32 flow_key_get(struct sk_buff *skb, int key)
 {
+       int nhoff = skb_network_offset(skb);
+
        switch (key) {
        case FLOW_KEY_SRC:
-               return flow_get_src(skb);
+               return flow_get_src(skb, nhoff);
        case FLOW_KEY_DST:
-               return flow_get_dst(skb);
+               return flow_get_dst(skb, nhoff);
        case FLOW_KEY_PROTO:
-               return flow_get_proto(skb);
+               return flow_get_proto(skb, nhoff);
        case FLOW_KEY_PROTO_SRC:
-               return flow_get_proto_src(skb);
+               return flow_get_proto_src(skb, nhoff);
        case FLOW_KEY_PROTO_DST:
-               return flow_get_proto_dst(skb);
+               return flow_get_proto_dst(skb, nhoff);
        case FLOW_KEY_IIF:
                return flow_get_iif(skb);
        case FLOW_KEY_PRIORITY:
@@ -333,13 +337,13 @@ static u32 flow_key_get(struct sk_buff *skb, int key)
        case FLOW_KEY_NFCT:
                return flow_get_nfct(skb);
        case FLOW_KEY_NFCT_SRC:
-               return flow_get_nfct_src(skb);
+               return flow_get_nfct_src(skb, nhoff);
        case FLOW_KEY_NFCT_DST:
-               return flow_get_nfct_dst(skb);
+               return flow_get_nfct_dst(skb, nhoff);
        case FLOW_KEY_NFCT_PROTO_SRC:
-               return flow_get_nfct_proto_src(skb);
+               return flow_get_nfct_proto_src(skb, nhoff);
        case FLOW_KEY_NFCT_PROTO_DST:
-               return flow_get_nfct_proto_dst(skb);
+               return flow_get_nfct_proto_dst(skb, nhoff);
        case FLOW_KEY_RTCLASSID:
                return flow_get_rtclassid(skb);
        case FLOW_KEY_SKUID: