145 lines
3.1 KiB
C
145 lines
3.1 KiB
C
#include <linux/skbuff.h>
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#include <linux/export.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <linux/if_vlan.h>
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#include <net/ip.h>
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#include <linux/if_tunnel.h>
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#include <linux/if_pppox.h>
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#include <linux/ppp_defs.h>
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#include <net/flow_keys.h>
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/* copy saddr & daddr, possibly using 64bit load/store
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* Equivalent to : flow->src = iph->saddr;
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* flow->dst = iph->daddr;
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*/
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static void iph_to_flow_copy_addrs(struct flow_keys *flow, const struct iphdr *iph)
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{
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BUILD_BUG_ON(offsetof(typeof(*flow), dst) !=
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offsetof(typeof(*flow), src) + sizeof(flow->src));
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memcpy(&flow->src, &iph->saddr, sizeof(flow->src) + sizeof(flow->dst));
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}
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bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow)
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{
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int poff, nhoff = skb_network_offset(skb);
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u8 ip_proto;
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__be16 proto = skb->protocol;
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memset(flow, 0, sizeof(*flow));
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again:
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switch (proto) {
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case __constant_htons(ETH_P_IP): {
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const struct iphdr *iph;
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struct iphdr _iph;
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ip:
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iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
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if (!iph)
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return false;
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if (ip_is_fragment(iph))
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ip_proto = 0;
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else
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ip_proto = iph->protocol;
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iph_to_flow_copy_addrs(flow, iph);
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nhoff += iph->ihl * 4;
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break;
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}
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case __constant_htons(ETH_P_IPV6): {
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const struct ipv6hdr *iph;
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struct ipv6hdr _iph;
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ipv6:
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iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
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if (!iph)
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return false;
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ip_proto = iph->nexthdr;
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flow->src = iph->saddr.s6_addr32[3];
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flow->dst = iph->daddr.s6_addr32[3];
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nhoff += sizeof(struct ipv6hdr);
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break;
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}
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case __constant_htons(ETH_P_8021Q): {
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const struct vlan_hdr *vlan;
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struct vlan_hdr _vlan;
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vlan = skb_header_pointer(skb, nhoff, sizeof(_vlan), &_vlan);
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if (!vlan)
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return false;
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proto = vlan->h_vlan_encapsulated_proto;
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nhoff += sizeof(*vlan);
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goto again;
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}
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case __constant_htons(ETH_P_PPP_SES): {
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struct {
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struct pppoe_hdr hdr;
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__be16 proto;
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} *hdr, _hdr;
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hdr = skb_header_pointer(skb, nhoff, sizeof(_hdr), &_hdr);
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if (!hdr)
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return false;
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proto = hdr->proto;
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nhoff += PPPOE_SES_HLEN;
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switch (proto) {
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case __constant_htons(PPP_IP):
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goto ip;
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case __constant_htons(PPP_IPV6):
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goto ipv6;
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default:
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return false;
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}
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}
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default:
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return false;
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}
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switch (ip_proto) {
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case IPPROTO_GRE: {
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struct gre_hdr {
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__be16 flags;
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__be16 proto;
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} *hdr, _hdr;
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hdr = skb_header_pointer(skb, nhoff, sizeof(_hdr), &_hdr);
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if (!hdr)
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return false;
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/*
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* Only look inside GRE if version zero and no
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* routing
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*/
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if (!(hdr->flags & (GRE_VERSION|GRE_ROUTING))) {
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proto = hdr->proto;
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nhoff += 4;
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if (hdr->flags & GRE_CSUM)
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nhoff += 4;
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if (hdr->flags & GRE_KEY)
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nhoff += 4;
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if (hdr->flags & GRE_SEQ)
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nhoff += 4;
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goto again;
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}
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break;
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}
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case IPPROTO_IPIP:
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goto again;
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default:
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break;
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}
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flow->ip_proto = ip_proto;
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poff = proto_ports_offset(ip_proto);
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if (poff >= 0) {
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__be32 *ports, _ports;
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nhoff += poff;
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ports = skb_header_pointer(skb, nhoff, sizeof(_ports), &_ports);
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if (ports)
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flow->ports = *ports;
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}
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return true;
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}
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EXPORT_SYMBOL(skb_flow_dissect);
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