1 #include <linux/skbuff.h> 2 #include <linux/ip.h> 3 #include <linux/ipv6.h> 4 #include <linux/if_vlan.h> 5 #include <net/ip.h> 6 #include <linux/if_tunnel.h> 7 #include <linux/if_pppox.h> 8 #include <linux/ppp_defs.h> 9 #include <net/flow_keys.h> 10 11 /* copy saddr & daddr, possibly using 64bit load/store 12 * Equivalent to : flow->src = iph->saddr; 13 * flow->dst = iph->daddr; 14 */ 15 static void iph_to_flow_copy_addrs(struct flow_keys *flow, const struct iphdr *iph) 16 { 17 BUILD_BUG_ON(offsetof(typeof(*flow), dst) != 18 offsetof(typeof(*flow), src) + sizeof(flow->src)); 19 memcpy(&flow->src, &iph->saddr, sizeof(flow->src) + sizeof(flow->dst)); 20 } 21 22 bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow) 23 { 24 int poff, nhoff = skb_network_offset(skb); 25 u8 ip_proto; 26 __be16 proto = skb->protocol; 27 28 memset(flow, 0, sizeof(*flow)); 29 30 again: 31 switch (proto) { 32 case __constant_htons(ETH_P_IP): { 33 const struct iphdr *iph; 34 struct iphdr _iph; 35 ip: 36 iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph); 37 if (!iph) 38 return false; 39 40 if (ip_is_fragment(iph)) 41 ip_proto = 0; 42 else 43 ip_proto = iph->protocol; 44 iph_to_flow_copy_addrs(flow, iph); 45 nhoff += iph->ihl * 4; 46 break; 47 } 48 case __constant_htons(ETH_P_IPV6): { 49 const struct ipv6hdr *iph; 50 struct ipv6hdr _iph; 51 ipv6: 52 iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph); 53 if (!iph) 54 return false; 55 56 ip_proto = iph->nexthdr; 57 flow->src = iph->saddr.s6_addr32[3]; 58 flow->dst = iph->daddr.s6_addr32[3]; 59 nhoff += sizeof(struct ipv6hdr); 60 break; 61 } 62 case __constant_htons(ETH_P_8021Q): { 63 const struct vlan_hdr *vlan; 64 struct vlan_hdr _vlan; 65 66 vlan = skb_header_pointer(skb, nhoff, sizeof(_vlan), &_vlan); 67 if (!vlan) 68 return false; 69 70 proto = vlan->h_vlan_encapsulated_proto; 71 nhoff += sizeof(*vlan); 72 goto again; 73 } 74 case __constant_htons(ETH_P_PPP_SES): { 75 struct { 76 struct pppoe_hdr hdr; 77 __be16 proto; 78 } *hdr, _hdr; 79 hdr = skb_header_pointer(skb, nhoff, sizeof(_hdr), &_hdr); 80 if (!hdr) 81 return false; 82 proto = hdr->proto; 83 nhoff += PPPOE_SES_HLEN; 84 switch (proto) { 85 case __constant_htons(PPP_IP): 86 goto ip; 87 case __constant_htons(PPP_IPV6): 88 goto ipv6; 89 default: 90 return false; 91 } 92 } 93 default: 94 return false; 95 } 96 97 switch (ip_proto) { 98 case IPPROTO_GRE: { 99 struct gre_hdr { 100 __be16 flags; 101 __be16 proto; 102 } *hdr, _hdr; 103 104 hdr = skb_header_pointer(skb, nhoff, sizeof(_hdr), &_hdr); 105 if (!hdr) 106 return false; 107 /* 108 * Only look inside GRE if version zero and no 109 * routing 110 */ 111 if (!(hdr->flags & (GRE_VERSION|GRE_ROUTING))) { 112 proto = hdr->proto; 113 nhoff += 4; 114 if (hdr->flags & GRE_CSUM) 115 nhoff += 4; 116 if (hdr->flags & GRE_KEY) 117 nhoff += 4; 118 if (hdr->flags & GRE_SEQ) 119 nhoff += 4; 120 goto again; 121 } 122 break; 123 } 124 case IPPROTO_IPIP: 125 goto again; 126 default: 127 break; 128 } 129 130 flow->ip_proto = ip_proto; 131 poff = proto_ports_offset(ip_proto); 132 if (poff >= 0) { 133 __be32 *ports, _ports; 134 135 nhoff += poff; 136 ports = skb_header_pointer(skb, nhoff, sizeof(_ports), &_ports); 137 if (ports) 138 flow->ports = *ports; 139 } 140 141 return true; 142 } 143 EXPORT_SYMBOL(skb_flow_dissect); 144