1 // SPDX-License-Identifier: GPL-2.0
6 #include <linux/pkt_cls.h>
9 #include <linux/if_ether.h>
10 #include <linux/icmp.h>
12 #include <linux/ipv6.h>
13 #include <linux/tcp.h>
14 #include <linux/udp.h>
15 #include <linux/if_packet.h>
16 #include <sys/socket.h>
17 #include <linux/if_tunnel.h>
18 #include <linux/mpls.h>
19 #include "bpf_helpers.h"
20 #include "bpf_endian.h"
22 int _version SEC("version") = 1;
23 #define PROG(F) SEC(#F) int bpf_func_##F
25 /* These are the identifiers of the BPF programs that will be used in tail
26 * calls. Name is limited to 16 characters, with the terminating character and
27 * bpf_func_ above, we have only 6 to work with, anything after will be cropped.
32 IPV6OP, /* Destination/Hop-by-Hop Options IPv6 Extension header */
33 IPV6FR, /* Fragmentation IPv6 Extension Header */
39 #define IP_OFFSET 0x1FFF
41 #define IP6_OFFSET 0xFFF8
45 __be16 h_vlan_encapsulated_proto;
57 __be32 identification;
61 __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
62 __uint(max_entries, 8);
63 __uint(key_size, sizeof(__u32));
64 __uint(value_size, sizeof(__u32));
65 } jmp_table SEC(".maps");
68 __uint(type, BPF_MAP_TYPE_ARRAY);
69 __uint(max_entries, 1);
71 __type(value, struct bpf_flow_keys);
72 } last_dissection SEC(".maps");
74 static __always_inline int export_flow_keys(struct bpf_flow_keys *keys,
77 struct bpf_flow_keys *val;
80 val = bpf_map_lookup_elem(&last_dissection, &key);
82 memcpy(val, keys, sizeof(*val));
86 static __always_inline void *bpf_flow_dissect_get_header(struct __sk_buff *skb,
90 void *data_end = (void *)(long)skb->data_end;
91 void *data = (void *)(long)skb->data;
92 __u16 thoff = skb->flow_keys->thoff;
95 /* Verifies this variable offset does not overflow */
96 if (thoff > (USHRT_MAX - hdr_size))
100 if (hdr + hdr_size <= data_end)
103 if (bpf_skb_load_bytes(skb, thoff, buffer, hdr_size))
109 /* Dispatches on ETHERTYPE */
110 static __always_inline int parse_eth_proto(struct __sk_buff *skb, __be16 proto)
112 struct bpf_flow_keys *keys = skb->flow_keys;
115 case bpf_htons(ETH_P_IP):
116 bpf_tail_call(skb, &jmp_table, IP);
118 case bpf_htons(ETH_P_IPV6):
119 bpf_tail_call(skb, &jmp_table, IPV6);
121 case bpf_htons(ETH_P_MPLS_MC):
122 case bpf_htons(ETH_P_MPLS_UC):
123 bpf_tail_call(skb, &jmp_table, MPLS);
125 case bpf_htons(ETH_P_8021Q):
126 case bpf_htons(ETH_P_8021AD):
127 bpf_tail_call(skb, &jmp_table, VLAN);
130 /* Protocol not supported */
131 return export_flow_keys(keys, BPF_DROP);
134 return export_flow_keys(keys, BPF_DROP);
137 SEC("flow_dissector")
138 int _dissect(struct __sk_buff *skb)
140 struct bpf_flow_keys *keys = skb->flow_keys;
142 return parse_eth_proto(skb, keys->n_proto);
145 /* Parses on IPPROTO_* */
146 static __always_inline int parse_ip_proto(struct __sk_buff *skb, __u8 proto)
148 struct bpf_flow_keys *keys = skb->flow_keys;
149 void *data_end = (void *)(long)skb->data_end;
150 struct icmphdr *icmp, _icmp;
151 struct gre_hdr *gre, _gre;
152 struct ethhdr *eth, _eth;
153 struct tcphdr *tcp, _tcp;
154 struct udphdr *udp, _udp;
156 keys->ip_proto = proto;
159 icmp = bpf_flow_dissect_get_header(skb, sizeof(*icmp), &_icmp);
161 return export_flow_keys(keys, BPF_DROP);
162 return export_flow_keys(keys, BPF_OK);
164 keys->is_encap = true;
165 return parse_eth_proto(skb, bpf_htons(ETH_P_IP));
167 keys->is_encap = true;
168 return parse_eth_proto(skb, bpf_htons(ETH_P_IPV6));
170 gre = bpf_flow_dissect_get_header(skb, sizeof(*gre), &_gre);
172 return export_flow_keys(keys, BPF_DROP);
174 if (bpf_htons(gre->flags & GRE_VERSION))
175 /* Only inspect standard GRE packets with version 0 */
176 return export_flow_keys(keys, BPF_OK);
178 keys->thoff += sizeof(*gre); /* Step over GRE Flags and Proto */
179 if (GRE_IS_CSUM(gre->flags))
180 keys->thoff += 4; /* Step over chksum and Padding */
181 if (GRE_IS_KEY(gre->flags))
182 keys->thoff += 4; /* Step over key */
183 if (GRE_IS_SEQ(gre->flags))
184 keys->thoff += 4; /* Step over sequence number */
186 keys->is_encap = true;
188 if (gre->proto == bpf_htons(ETH_P_TEB)) {
189 eth = bpf_flow_dissect_get_header(skb, sizeof(*eth),
192 return export_flow_keys(keys, BPF_DROP);
194 keys->thoff += sizeof(*eth);
196 return parse_eth_proto(skb, eth->h_proto);
198 return parse_eth_proto(skb, gre->proto);
201 tcp = bpf_flow_dissect_get_header(skb, sizeof(*tcp), &_tcp);
203 return export_flow_keys(keys, BPF_DROP);
206 return export_flow_keys(keys, BPF_DROP);
208 if ((__u8 *)tcp + (tcp->doff << 2) > data_end)
209 return export_flow_keys(keys, BPF_DROP);
211 keys->sport = tcp->source;
212 keys->dport = tcp->dest;
213 return export_flow_keys(keys, BPF_OK);
215 case IPPROTO_UDPLITE:
216 udp = bpf_flow_dissect_get_header(skb, sizeof(*udp), &_udp);
218 return export_flow_keys(keys, BPF_DROP);
220 keys->sport = udp->source;
221 keys->dport = udp->dest;
222 return export_flow_keys(keys, BPF_OK);
224 return export_flow_keys(keys, BPF_DROP);
227 return export_flow_keys(keys, BPF_DROP);
230 static __always_inline int parse_ipv6_proto(struct __sk_buff *skb, __u8 nexthdr)
232 struct bpf_flow_keys *keys = skb->flow_keys;
234 keys->ip_proto = nexthdr;
236 case IPPROTO_HOPOPTS:
237 case IPPROTO_DSTOPTS:
238 bpf_tail_call(skb, &jmp_table, IPV6OP);
240 case IPPROTO_FRAGMENT:
241 bpf_tail_call(skb, &jmp_table, IPV6FR);
244 return parse_ip_proto(skb, nexthdr);
247 return export_flow_keys(keys, BPF_DROP);
250 PROG(IP)(struct __sk_buff *skb)
252 void *data_end = (void *)(long)skb->data_end;
253 struct bpf_flow_keys *keys = skb->flow_keys;
254 void *data = (void *)(long)skb->data;
255 struct iphdr *iph, _iph;
258 iph = bpf_flow_dissect_get_header(skb, sizeof(*iph), &_iph);
260 return export_flow_keys(keys, BPF_DROP);
262 /* IP header cannot be smaller than 20 bytes */
264 return export_flow_keys(keys, BPF_DROP);
266 keys->addr_proto = ETH_P_IP;
267 keys->ipv4_src = iph->saddr;
268 keys->ipv4_dst = iph->daddr;
270 keys->thoff += iph->ihl << 2;
271 if (data + keys->thoff > data_end)
272 return export_flow_keys(keys, BPF_DROP);
274 if (iph->frag_off & bpf_htons(IP_MF | IP_OFFSET)) {
275 keys->is_frag = true;
276 if (iph->frag_off & bpf_htons(IP_OFFSET))
277 /* From second fragment on, packets do not have headers
282 keys->is_first_frag = true;
286 return export_flow_keys(keys, BPF_OK);
288 return parse_ip_proto(skb, iph->protocol);
291 PROG(IPV6)(struct __sk_buff *skb)
293 struct bpf_flow_keys *keys = skb->flow_keys;
294 struct ipv6hdr *ip6h, _ip6h;
296 ip6h = bpf_flow_dissect_get_header(skb, sizeof(*ip6h), &_ip6h);
298 return export_flow_keys(keys, BPF_DROP);
300 keys->addr_proto = ETH_P_IPV6;
301 memcpy(&keys->ipv6_src, &ip6h->saddr, 2*sizeof(ip6h->saddr));
303 keys->thoff += sizeof(struct ipv6hdr);
305 return parse_ipv6_proto(skb, ip6h->nexthdr);
308 PROG(IPV6OP)(struct __sk_buff *skb)
310 struct bpf_flow_keys *keys = skb->flow_keys;
311 struct ipv6_opt_hdr *ip6h, _ip6h;
313 ip6h = bpf_flow_dissect_get_header(skb, sizeof(*ip6h), &_ip6h);
315 return export_flow_keys(keys, BPF_DROP);
317 /* hlen is in 8-octets and does not include the first 8 bytes
320 skb->flow_keys->thoff += (1 + ip6h->hdrlen) << 3;
322 return parse_ipv6_proto(skb, ip6h->nexthdr);
325 PROG(IPV6FR)(struct __sk_buff *skb)
327 struct bpf_flow_keys *keys = skb->flow_keys;
328 struct frag_hdr *fragh, _fragh;
330 fragh = bpf_flow_dissect_get_header(skb, sizeof(*fragh), &_fragh);
332 return export_flow_keys(keys, BPF_DROP);
334 keys->thoff += sizeof(*fragh);
335 keys->is_frag = true;
336 if (!(fragh->frag_off & bpf_htons(IP6_OFFSET)))
337 keys->is_first_frag = true;
339 return parse_ipv6_proto(skb, fragh->nexthdr);
342 PROG(MPLS)(struct __sk_buff *skb)
344 struct bpf_flow_keys *keys = skb->flow_keys;
345 struct mpls_label *mpls, _mpls;
347 mpls = bpf_flow_dissect_get_header(skb, sizeof(*mpls), &_mpls);
349 return export_flow_keys(keys, BPF_DROP);
351 return export_flow_keys(keys, BPF_OK);
354 PROG(VLAN)(struct __sk_buff *skb)
356 struct bpf_flow_keys *keys = skb->flow_keys;
357 struct vlan_hdr *vlan, _vlan;
359 /* Account for double-tagging */
360 if (keys->n_proto == bpf_htons(ETH_P_8021AD)) {
361 vlan = bpf_flow_dissect_get_header(skb, sizeof(*vlan), &_vlan);
363 return export_flow_keys(keys, BPF_DROP);
365 if (vlan->h_vlan_encapsulated_proto != bpf_htons(ETH_P_8021Q))
366 return export_flow_keys(keys, BPF_DROP);
368 keys->nhoff += sizeof(*vlan);
369 keys->thoff += sizeof(*vlan);
372 vlan = bpf_flow_dissect_get_header(skb, sizeof(*vlan), &_vlan);
374 return export_flow_keys(keys, BPF_DROP);
376 keys->nhoff += sizeof(*vlan);
377 keys->thoff += sizeof(*vlan);
378 /* Only allow 8021AD + 8021Q double tagging and no triple tagging.*/
379 if (vlan->h_vlan_encapsulated_proto == bpf_htons(ETH_P_8021AD) ||
380 vlan->h_vlan_encapsulated_proto == bpf_htons(ETH_P_8021Q))
381 return export_flow_keys(keys, BPF_DROP);
383 keys->n_proto = vlan->h_vlan_encapsulated_proto;
384 return parse_eth_proto(skb, vlan->h_vlan_encapsulated_proto);
387 char __license[] SEC("license") = "GPL";