LXR linux/tools/testing/selftests/bpf/progs/bpf

   1// SPDX-License-Identifier: GPL-2.0
   2#include <limits.h>
   3#include <stddef.h>
   4#include <stdbool.h>
   5#include <string.h>
   6#include <linux/pkt_cls.h>
   7#include <linux/bpf.h>
   8#include <linux/in.h>
   9#include <linux/if_ether.h>
  10#include <linux/icmp.h>
  11#include <linux/ip.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"
  21
  22int _version SEC("version") = 1;
  23#define PROG(F) SEC(#F) int bpf_func_##F
  24
  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.
  28 */
  29enum {
  30        IP,
  31        IPV6,
  32        IPV6OP, /* Destination/Hop-by-Hop Options IPv6 Extension header */
  33        IPV6FR, /* Fragmentation IPv6 Extension Header */
  34        MPLS,
  35        VLAN,
  36};
  37
  38#define IP_MF           0x2000
  39#define IP_OFFSET       0x1FFF
  40#define IP6_MF          0x0001
  41#define IP6_OFFSET      0xFFF8
  42
  43struct vlan_hdr {
  44        __be16 h_vlan_TCI;
  45        __be16 h_vlan_encapsulated_proto;
  46};
  47
  48struct gre_hdr {
  49        __be16 flags;
  50        __be16 proto;
  51};
  52
  53struct frag_hdr {
  54        __u8 nexthdr;
  55        __u8 reserved;
  56        __be16 frag_off;
  57        __be32 identification;
  58};
  59
  60struct {
  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");
  66
  67struct {
  68        __uint(type, BPF_MAP_TYPE_ARRAY);
  69        __uint(max_entries, 1);
  70        __type(key, __u32);
  71        __type(value, struct bpf_flow_keys);
  72} last_dissection SEC(".maps");
  73
  74static __always_inline int export_flow_keys(struct bpf_flow_keys *keys,
  75                                            int ret)
  76{
  77        struct bpf_flow_keys *val;
  78        __u32 key = 0;
  79
  80        val = bpf_map_lookup_elem(&last_dissection, &key);
  81        if (val)
  82                memcpy(val, keys, sizeof(*val));
  83        return ret;
  84}
  85
  86static __always_inline void *bpf_flow_dissect_get_header(struct __sk_buff *skb,
  87                                                         __u16 hdr_size,
  88                                                         void *buffer)
  89{
  90        void *data_end = (void *)(long)skb->data_end;
  91        void *data = (void *)(long)skb->data;
  92        __u16 thoff = skb->flow_keys->thoff;
  93        __u8 *hdr;
  94
  95        /* Verifies this variable offset does not overflow */
  96        if (thoff > (USHRT_MAX - hdr_size))
  97                return NULL;
  98
  99        hdr = data + thoff;
 100        if (hdr + hdr_size <= data_end)
 101                return hdr;
 102
 103        if (bpf_skb_load_bytes(skb, thoff, buffer, hdr_size))
 104                return NULL;
 105
 106        return buffer;
 107}
 108
 109/* Dispatches on ETHERTYPE */
 110static __always_inline int parse_eth_proto(struct __sk_buff *skb, __be16 proto)
 111{
 112        struct bpf_flow_keys *keys = skb->flow_keys;
 113
 114        switch (proto) {
 115        case bpf_htons(ETH_P_IP):
 116                bpf_tail_call(skb, &jmp_table, IP);
 117                break;
 118        case bpf_htons(ETH_P_IPV6):
 119                bpf_tail_call(skb, &jmp_table, IPV6);
 120                break;
 121        case bpf_htons(ETH_P_MPLS_MC):
 122        case bpf_htons(ETH_P_MPLS_UC):
 123                bpf_tail_call(skb, &jmp_table, MPLS);
 124                break;
 125        case bpf_htons(ETH_P_8021Q):
 126        case bpf_htons(ETH_P_8021AD):
 127                bpf_tail_call(skb, &jmp_table, VLAN);
 128                break;
 129        default:
 130                /* Protocol not supported */
 131                return export_flow_keys(keys, BPF_DROP);
 132        }
 133
 134        return export_flow_keys(keys, BPF_DROP);
 135}
 136
 137SEC("flow_dissector")
 138int _dissect(struct __sk_buff *skb)
 139{
 140        struct bpf_flow_keys *keys = skb->flow_keys;
 141
 142        return parse_eth_proto(skb, keys->n_proto);
 143}
 144
 145/* Parses on IPPROTO_* */
 146static __always_inline int parse_ip_proto(struct __sk_buff *skb, __u8 proto)
 147{
 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;
 155
 156        keys->ip_proto = proto;
 157        switch (proto) {
 158        case IPPROTO_ICMP:
 159                icmp = bpf_flow_dissect_get_header(skb, sizeof(*icmp), &_icmp);
 160                if (!icmp)
 161                        return export_flow_keys(keys, BPF_DROP);
 162                return export_flow_keys(keys, BPF_OK);
 163        case IPPROTO_IPIP:
 164                keys->is_encap = true;
 165                return parse_eth_proto(skb, bpf_htons(ETH_P_IP));
 166        case IPPROTO_IPV6:
 167                keys->is_encap = true;
 168                return parse_eth_proto(skb, bpf_htons(ETH_P_IPV6));
 169        case IPPROTO_GRE:
 170                gre = bpf_flow_dissect_get_header(skb, sizeof(*gre), &_gre);
 171                if (!gre)
 172                        return export_flow_keys(keys, BPF_DROP);
 173
 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);
 177
 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 */
 185
 186                keys->is_encap = true;
 187
 188                if (gre->proto == bpf_htons(ETH_P_TEB)) {
 189                        eth = bpf_flow_dissect_get_header(skb, sizeof(*eth),
 190                                                          &_eth);
 191                        if (!eth)
 192                                return export_flow_keys(keys, BPF_DROP);
 193
 194                        keys->thoff += sizeof(*eth);
 195
 196                        return parse_eth_proto(skb, eth->h_proto);
 197                } else {
 198                        return parse_eth_proto(skb, gre->proto);
 199                }
 200        case IPPROTO_TCP:
 201                tcp = bpf_flow_dissect_get_header(skb, sizeof(*tcp), &_tcp);
 202                if (!tcp)
 203                        return export_flow_keys(keys, BPF_DROP);
 204
 205                if (tcp->doff < 5)
 206                        return export_flow_keys(keys, BPF_DROP);
 207
 208                if ((__u8 *)tcp + (tcp->doff << 2) > data_end)
 209                        return export_flow_keys(keys, BPF_DROP);
 210
 211                keys->sport = tcp->source;
 212                keys->dport = tcp->dest;
 213                return export_flow_keys(keys, BPF_OK);
 214        case IPPROTO_UDP:
 215        case IPPROTO_UDPLITE:
 216                udp = bpf_flow_dissect_get_header(skb, sizeof(*udp), &_udp);
 217                if (!udp)
 218                        return export_flow_keys(keys, BPF_DROP);
 219
 220                keys->sport = udp->source;
 221                keys->dport = udp->dest;
 222                return export_flow_keys(keys, BPF_OK);
 223        default:
 224                return export_flow_keys(keys, BPF_DROP);
 225        }
 226
 227        return export_flow_keys(keys, BPF_DROP);
 228}
 229
 230static __always_inline int parse_ipv6_proto(struct __sk_buff *skb, __u8 nexthdr)
 231{
 232        struct bpf_flow_keys *keys = skb->flow_keys;
 233
 234        keys->ip_proto = nexthdr;
 235        switch (nexthdr) {
 236        case IPPROTO_HOPOPTS:
 237        case IPPROTO_DSTOPTS:
 238                bpf_tail_call(skb, &jmp_table, IPV6OP);
 239                break;
 240        case IPPROTO_FRAGMENT:
 241                bpf_tail_call(skb, &jmp_table, IPV6FR);
 242                break;
 243        default:
 244                return parse_ip_proto(skb, nexthdr);
 245        }
 246
 247        return export_flow_keys(keys, BPF_DROP);
 248}
 249
 250PROG(IP)(struct __sk_buff *skb)
 251{
 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;
 256        bool done = false;
 257
 258        iph = bpf_flow_dissect_get_header(skb, sizeof(*iph), &_iph);
 259        if (!iph)
 260                return export_flow_keys(keys, BPF_DROP);
 261
 262        /* IP header cannot be smaller than 20 bytes */
 263        if (iph->ihl < 5)
 264                return export_flow_keys(keys, BPF_DROP);
 265
 266        keys->addr_proto = ETH_P_IP;
 267        keys->ipv4_src = iph->saddr;
 268        keys->ipv4_dst = iph->daddr;
 269
 270        keys->thoff += iph->ihl << 2;
 271        if (data + keys->thoff > data_end)
 272                return export_flow_keys(keys, BPF_DROP);
 273
 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
 278                         * we can parse.
 279                         */
 280                        done = true;
 281                else
 282                        keys->is_first_frag = true;
 283        }
 284
 285        if (done)
 286                return export_flow_keys(keys, BPF_OK);
 287
 288        return parse_ip_proto(skb, iph->protocol);
 289}
 290
 291PROG(IPV6)(struct __sk_buff *skb)
 292{
 293        struct bpf_flow_keys *keys = skb->flow_keys;
 294        struct ipv6hdr *ip6h, _ip6h;
 295
 296        ip6h = bpf_flow_dissect_get_header(skb, sizeof(*ip6h), &_ip6h);
 297        if (!ip6h)
 298                return export_flow_keys(keys, BPF_DROP);
 299
 300        keys->addr_proto = ETH_P_IPV6;
 301        memcpy(&keys->ipv6_src, &ip6h->saddr, 2*sizeof(ip6h->saddr));
 302
 303        keys->thoff += sizeof(struct ipv6hdr);
 304
 305        return parse_ipv6_proto(skb, ip6h->nexthdr);
 306}
 307
 308PROG(IPV6OP)(struct __sk_buff *skb)
 309{
 310        struct bpf_flow_keys *keys = skb->flow_keys;
 311        struct ipv6_opt_hdr *ip6h, _ip6h;
 312
 313        ip6h = bpf_flow_dissect_get_header(skb, sizeof(*ip6h), &_ip6h);
 314        if (!ip6h)
 315                return export_flow_keys(keys, BPF_DROP);
 316
 317        /* hlen is in 8-octets and does not include the first 8 bytes
 318         * of the header
 319         */
 320        skb->flow_keys->thoff += (1 + ip6h->hdrlen) << 3;
 321
 322        return parse_ipv6_proto(skb, ip6h->nexthdr);
 323}
 324
 325PROG(IPV6FR)(struct __sk_buff *skb)
 326{
 327        struct bpf_flow_keys *keys = skb->flow_keys;
 328        struct frag_hdr *fragh, _fragh;
 329
 330        fragh = bpf_flow_dissect_get_header(skb, sizeof(*fragh), &_fragh);
 331        if (!fragh)
 332                return export_flow_keys(keys, BPF_DROP);
 333
 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;
 338
 339        return parse_ipv6_proto(skb, fragh->nexthdr);
 340}
 341
 342PROG(MPLS)(struct __sk_buff *skb)
 343{
 344        struct bpf_flow_keys *keys = skb->flow_keys;
 345        struct mpls_label *mpls, _mpls;
 346
 347        mpls = bpf_flow_dissect_get_header(skb, sizeof(*mpls), &_mpls);
 348        if (!mpls)
 349                return export_flow_keys(keys, BPF_DROP);
 350
 351        return export_flow_keys(keys, BPF_OK);
 352}
 353
 354PROG(VLAN)(struct __sk_buff *skb)
 355{
 356        struct bpf_flow_keys *keys = skb->flow_keys;
 357        struct vlan_hdr *vlan, _vlan;
 358
 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);
 362                if (!vlan)
 363                        return export_flow_keys(keys, BPF_DROP);
 364
 365                if (vlan->h_vlan_encapsulated_proto != bpf_htons(ETH_P_8021Q))
 366                        return export_flow_keys(keys, BPF_DROP);
 367
 368                keys->nhoff += sizeof(*vlan);
 369                keys->thoff += sizeof(*vlan);
 370        }
 371
 372        vlan = bpf_flow_dissect_get_header(skb, sizeof(*vlan), &_vlan);
 373        if (!vlan)
 374                return export_flow_keys(keys, BPF_DROP);
 375
 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);
 382
 383        keys->n_proto = vlan->h_vlan_encapsulated_proto;
 384        return parse_eth_proto(skb, vlan->h_vlan_encapsulated_proto);
 385}
 386
 387char __license[] SEC("license") = "GPL";
 388