![Jiri Pirko](/assets/img/avatar_default.png)
next to its user. No relation to flow_dissector so it makes no sense to have it in flow_dissector.c Signed-off-by: Jiri Pirko <jiri@resnulli.us> Signed-off-by: David S. Miller <davem@davemloft.net>
434 lines
10 KiB
C
434 lines
10 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 <net/ipv6.h>
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#include <linux/igmp.h>
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#include <linux/icmp.h>
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#include <linux/sctp.h>
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#include <linux/dccp.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_dissector.h>
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#include <scsi/fc/fc_fcoe.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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/**
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* __skb_flow_get_ports - extract the upper layer ports and return them
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* @skb: sk_buff to extract the ports from
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* @thoff: transport header offset
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* @ip_proto: protocol for which to get port offset
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* @data: raw buffer pointer to the packet, if NULL use skb->data
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* @hlen: packet header length, if @data is NULL use skb_headlen(skb)
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*
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* The function will try to retrieve the ports at offset thoff + poff where poff
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* is the protocol port offset returned from proto_ports_offset
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*/
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__be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
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void *data, int hlen)
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{
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int poff = proto_ports_offset(ip_proto);
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if (!data) {
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data = skb->data;
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hlen = skb_headlen(skb);
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}
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if (poff >= 0) {
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__be32 *ports, _ports;
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ports = __skb_header_pointer(skb, thoff + poff,
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sizeof(_ports), data, hlen, &_ports);
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if (ports)
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return *ports;
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}
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return 0;
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}
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EXPORT_SYMBOL(__skb_flow_get_ports);
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/**
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* __skb_flow_dissect - extract the flow_keys struct and return it
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* @skb: sk_buff to extract the flow from, can be NULL if the rest are specified
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* @data: raw buffer pointer to the packet, if NULL use skb->data
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* @proto: protocol for which to get the flow, if @data is NULL use skb->protocol
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* @nhoff: network header offset, if @data is NULL use skb_network_offset(skb)
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* @hlen: packet header length, if @data is NULL use skb_headlen(skb)
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*
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* The function will try to retrieve the struct flow_keys from either the skbuff
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* or a raw buffer specified by the rest parameters
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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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void *data, __be16 proto, int nhoff, int hlen)
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{
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u8 ip_proto;
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if (!data) {
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data = skb->data;
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proto = skb->protocol;
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nhoff = skb_network_offset(skb);
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hlen = skb_headlen(skb);
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}
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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 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), data, hlen, &_iph);
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if (!iph || iph->ihl < 5)
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return false;
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nhoff += iph->ihl * 4;
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ip_proto = iph->protocol;
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if (ip_is_fragment(iph))
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ip_proto = 0;
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/* skip the address processing if skb is NULL. The assumption
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* here is that if there is no skb we are not looking for flow
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* info but lengths and protocols.
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*/
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if (!skb)
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break;
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iph_to_flow_copy_addrs(flow, iph);
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break;
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}
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case htons(ETH_P_IPV6): {
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const struct ipv6hdr *iph;
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struct ipv6hdr _iph;
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__be32 flow_label;
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ipv6:
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iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_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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nhoff += sizeof(struct ipv6hdr);
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/* see comment above in IPv4 section */
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if (!skb)
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break;
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flow->src = (__force __be32)ipv6_addr_hash(&iph->saddr);
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flow->dst = (__force __be32)ipv6_addr_hash(&iph->daddr);
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flow_label = ip6_flowlabel(iph);
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if (flow_label) {
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/* Awesome, IPv6 packet has a flow label so we can
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* use that to represent the ports without any
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* further dissection.
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*/
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flow->n_proto = proto;
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flow->ip_proto = ip_proto;
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flow->ports = flow_label;
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flow->thoff = (u16)nhoff;
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return true;
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}
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break;
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}
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case htons(ETH_P_8021AD):
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case 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), data, hlen, &_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 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), data, hlen, &_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 htons(PPP_IP):
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goto ip;
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case 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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case htons(ETH_P_TIPC): {
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struct {
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__be32 pre[3];
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__be32 srcnode;
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} *hdr, _hdr;
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hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, hlen, &_hdr);
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if (!hdr)
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return false;
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flow->src = hdr->srcnode;
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flow->dst = 0;
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flow->n_proto = proto;
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flow->thoff = (u16)nhoff;
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return true;
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}
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case htons(ETH_P_FCOE):
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flow->thoff = (u16)(nhoff + FCOE_HEADER_LEN);
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/* fall through */
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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), data, hlen, &_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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if (proto == htons(ETH_P_TEB)) {
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const struct ethhdr *eth;
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struct ethhdr _eth;
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eth = __skb_header_pointer(skb, nhoff,
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sizeof(_eth),
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data, hlen, &_eth);
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if (!eth)
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return false;
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proto = eth->h_proto;
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nhoff += sizeof(*eth);
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}
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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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proto = htons(ETH_P_IP);
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goto ip;
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case IPPROTO_IPV6:
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proto = htons(ETH_P_IPV6);
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goto ipv6;
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default:
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break;
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}
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flow->n_proto = proto;
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flow->ip_proto = ip_proto;
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flow->thoff = (u16) nhoff;
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/* unless skb is set we don't need to record port info */
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if (skb)
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flow->ports = __skb_flow_get_ports(skb, nhoff, ip_proto,
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data, hlen);
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return true;
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}
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EXPORT_SYMBOL(__skb_flow_dissect);
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static u32 hashrnd __read_mostly;
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static __always_inline void __flow_hash_secret_init(void)
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{
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net_get_random_once(&hashrnd, sizeof(hashrnd));
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}
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static __always_inline u32 __flow_hash_3words(u32 a, u32 b, u32 c, u32 keyval)
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{
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return jhash_3words(a, b, c, keyval);
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}
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static inline u32 __flow_hash_from_keys(struct flow_keys *keys, u32 keyval)
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{
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u32 hash;
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/* get a consistent hash (same value on both flow directions) */
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if (((__force u32)keys->dst < (__force u32)keys->src) ||
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(((__force u32)keys->dst == (__force u32)keys->src) &&
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((__force u16)keys->port16[1] < (__force u16)keys->port16[0]))) {
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swap(keys->dst, keys->src);
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swap(keys->port16[0], keys->port16[1]);
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}
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hash = __flow_hash_3words((__force u32)keys->dst,
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(__force u32)keys->src,
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(__force u32)keys->ports,
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keyval);
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if (!hash)
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hash = 1;
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return hash;
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}
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u32 flow_hash_from_keys(struct flow_keys *keys)
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{
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__flow_hash_secret_init();
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return __flow_hash_from_keys(keys, hashrnd);
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}
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EXPORT_SYMBOL(flow_hash_from_keys);
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static inline u32 ___skb_get_hash(const struct sk_buff *skb,
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struct flow_keys *keys, u32 keyval)
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{
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if (!skb_flow_dissect(skb, keys))
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return 0;
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return __flow_hash_from_keys(keys, keyval);
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}
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struct _flow_keys_digest_data {
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__be16 n_proto;
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u8 ip_proto;
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u8 padding;
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__be32 ports;
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__be32 src;
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__be32 dst;
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};
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void make_flow_keys_digest(struct flow_keys_digest *digest,
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const struct flow_keys *flow)
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{
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struct _flow_keys_digest_data *data =
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(struct _flow_keys_digest_data *)digest;
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BUILD_BUG_ON(sizeof(*data) > sizeof(*digest));
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memset(digest, 0, sizeof(*digest));
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data->n_proto = flow->n_proto;
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data->ip_proto = flow->ip_proto;
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data->ports = flow->ports;
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data->src = flow->src;
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data->dst = flow->dst;
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}
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EXPORT_SYMBOL(make_flow_keys_digest);
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/**
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* __skb_get_hash: calculate a flow hash
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* @skb: sk_buff to calculate flow hash from
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*
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* This function calculates a flow hash based on src/dst addresses
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* and src/dst port numbers. Sets hash in skb to non-zero hash value
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* on success, zero indicates no valid hash. Also, sets l4_hash in skb
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* if hash is a canonical 4-tuple hash over transport ports.
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*/
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void __skb_get_hash(struct sk_buff *skb)
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{
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struct flow_keys keys;
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u32 hash;
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__flow_hash_secret_init();
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hash = ___skb_get_hash(skb, &keys, hashrnd);
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if (!hash)
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return;
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if (keys.ports)
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skb->l4_hash = 1;
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skb->sw_hash = 1;
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skb->hash = hash;
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}
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EXPORT_SYMBOL(__skb_get_hash);
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__u32 skb_get_hash_perturb(const struct sk_buff *skb, u32 perturb)
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{
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struct flow_keys keys;
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return ___skb_get_hash(skb, &keys, perturb);
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}
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EXPORT_SYMBOL(skb_get_hash_perturb);
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u32 __skb_get_poff(const struct sk_buff *skb, void *data,
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const struct flow_keys *keys, int hlen)
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{
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u32 poff = keys->thoff;
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switch (keys->ip_proto) {
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case IPPROTO_TCP: {
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/* access doff as u8 to avoid unaligned access */
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const u8 *doff;
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u8 _doff;
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doff = __skb_header_pointer(skb, poff + 12, sizeof(_doff),
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data, hlen, &_doff);
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if (!doff)
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return poff;
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poff += max_t(u32, sizeof(struct tcphdr), (*doff & 0xF0) >> 2);
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break;
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}
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case IPPROTO_UDP:
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case IPPROTO_UDPLITE:
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poff += sizeof(struct udphdr);
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break;
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/* For the rest, we do not really care about header
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* extensions at this point for now.
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*/
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case IPPROTO_ICMP:
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poff += sizeof(struct icmphdr);
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break;
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case IPPROTO_ICMPV6:
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poff += sizeof(struct icmp6hdr);
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break;
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case IPPROTO_IGMP:
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poff += sizeof(struct igmphdr);
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break;
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case IPPROTO_DCCP:
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poff += sizeof(struct dccp_hdr);
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break;
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case IPPROTO_SCTP:
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poff += sizeof(struct sctphdr);
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break;
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}
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return poff;
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}
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/* skb_get_poff() returns the offset to the payload as far as it could
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* be dissected. The main user is currently BPF, so that we can dynamically
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* truncate packets without needing to push actual payload to the user
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* space and can analyze headers only, instead.
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*/
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u32 skb_get_poff(const struct sk_buff *skb)
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{
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struct flow_keys keys;
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if (!skb_flow_dissect(skb, &keys))
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return 0;
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return __skb_get_poff(skb, skb->data, &keys, skb_headlen(skb));
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}
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