1 #include <linux/skbuff.h> 2 #include <linux/export.h> 3 #include <linux/ip.h> 4 #include <linux/ipv6.h> 5 #include <linux/if_vlan.h> 6 #include <net/ip.h> 7 #include <net/ipv6.h> 8 #include <linux/if_tunnel.h> 9 #include <linux/if_pppox.h> 10 #include <linux/ppp_defs.h> 11 #include <net/flow_keys.h> 12 13 /* copy saddr & daddr, possibly using 64bit load/store 14 * Equivalent to : flow->src = iph->saddr; 15 * flow->dst = iph->daddr; 16 */ 17 static void iph_to_flow_copy_addrs(struct flow_keys *flow, const struct iphdr *iph) 18 { 19 BUILD_BUG_ON(offsetof(typeof(*flow), dst) != 20 offsetof(typeof(*flow), src) + sizeof(flow->src)); 21 memcpy(&flow->src, &iph->saddr, sizeof(flow->src) + sizeof(flow->dst)); 22 } 23 24 bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow) 25 { 26 int poff, nhoff = skb_network_offset(skb); 27 u8 ip_proto; 28 __be16 proto = skb->protocol; 29 30 memset(flow, 0, sizeof(*flow)); 31 32 again: 33 switch (proto) { 34 case __constant_htons(ETH_P_IP): { 35 const struct iphdr *iph; 36 struct iphdr _iph; 37 ip: 38 iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph); 39 if (!iph) 40 return false; 41 42 if (ip_is_fragment(iph)) 43 ip_proto = 0; 44 else 45 ip_proto = iph->protocol; 46 iph_to_flow_copy_addrs(flow, iph); 47 nhoff += iph->ihl * 4; 48 break; 49 } 50 case __constant_htons(ETH_P_IPV6): { 51 const struct ipv6hdr *iph; 52 struct ipv6hdr _iph; 53 ipv6: 54 iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph); 55 if (!iph) 56 return false; 57 58 ip_proto = iph->nexthdr; 59 flow->src = (__force __be32)ipv6_addr_hash(&iph->saddr); 60 flow->dst = (__force __be32)ipv6_addr_hash(&iph->daddr); 61 nhoff += sizeof(struct ipv6hdr); 62 break; 63 } 64 case __constant_htons(ETH_P_8021Q): { 65 const struct vlan_hdr *vlan; 66 struct vlan_hdr _vlan; 67 68 vlan = skb_header_pointer(skb, nhoff, sizeof(_vlan), &_vlan); 69 if (!vlan) 70 return false; 71 72 proto = vlan->h_vlan_encapsulated_proto; 73 nhoff += sizeof(*vlan); 74 goto again; 75 } 76 case __constant_htons(ETH_P_PPP_SES): { 77 struct { 78 struct pppoe_hdr hdr; 79 __be16 proto; 80 } *hdr, _hdr; 81 hdr = skb_header_pointer(skb, nhoff, sizeof(_hdr), &_hdr); 82 if (!hdr) 83 return false; 84 proto = hdr->proto; 85 nhoff += PPPOE_SES_HLEN; 86 switch (proto) { 87 case __constant_htons(PPP_IP): 88 goto ip; 89 case __constant_htons(PPP_IPV6): 90 goto ipv6; 91 default: 92 return false; 93 } 94 } 95 default: 96 return false; 97 } 98 99 switch (ip_proto) { 100 case IPPROTO_GRE: { 101 struct gre_hdr { 102 __be16 flags; 103 __be16 proto; 104 } *hdr, _hdr; 105 106 hdr = skb_header_pointer(skb, nhoff, sizeof(_hdr), &_hdr); 107 if (!hdr) 108 return false; 109 /* 110 * Only look inside GRE if version zero and no 111 * routing 112 */ 113 if (!(hdr->flags & (GRE_VERSION|GRE_ROUTING))) { 114 proto = hdr->proto; 115 nhoff += 4; 116 if (hdr->flags & GRE_CSUM) 117 nhoff += 4; 118 if (hdr->flags & GRE_KEY) 119 nhoff += 4; 120 if (hdr->flags & GRE_SEQ) 121 nhoff += 4; 122 goto again; 123 } 124 break; 125 } 126 case IPPROTO_IPIP: 127 goto again; 128 default: 129 break; 130 } 131 132 flow->ip_proto = ip_proto; 133 poff = proto_ports_offset(ip_proto); 134 if (poff >= 0) { 135 __be32 *ports, _ports; 136 137 nhoff += poff; 138 ports = skb_header_pointer(skb, nhoff, sizeof(_ports), &_ports); 139 if (ports) 140 flow->ports = *ports; 141 } 142 143 return true; 144 } 145 EXPORT_SYMBOL(skb_flow_dissect); 146