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selftests/bpf: run flow dissector tests in skb-less mode
Export last_dissection map from flow dissector and use a known place in tun driver to trigger BPF flow dissection. Signed-off-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Stanislav Fomichev
Daniel Borkmann
parent
c9cb2c1e11
commit
0905beec9f
4 changed files with 165 additions and 34 deletions
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@ -26,7 +26,7 @@ static void load_and_attach_program(void)
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struct bpf_object *obj;
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ret = bpf_flow_load(&obj, cfg_path_name, cfg_section_name,
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cfg_map_name, &prog_fd);
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cfg_map_name, NULL, &prog_fd, NULL);
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if (ret)
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error(1, 0, "bpf_flow_load %s", cfg_path_name);
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@ -9,10 +9,12 @@ static inline int bpf_flow_load(struct bpf_object **obj,
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const char *path,
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const char *section_name,
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const char *map_name,
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int *prog_fd)
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const char *keys_map_name,
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int *prog_fd,
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int *keys_fd)
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{
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struct bpf_program *prog, *main_prog;
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struct bpf_map *prog_array;
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struct bpf_map *prog_array, *keys;
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int prog_array_fd;
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int ret, fd, i;
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@ -37,6 +39,16 @@ static inline int bpf_flow_load(struct bpf_object **obj,
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if (prog_array_fd < 0)
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return ret;
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if (keys_map_name && keys_fd) {
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keys = bpf_object__find_map_by_name(*obj, keys_map_name);
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if (!keys)
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return -1;
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*keys_fd = bpf_map__fd(keys);
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if (*keys_fd < 0)
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return -1;
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}
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i = 0;
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bpf_object__for_each_program(prog, *obj) {
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fd = bpf_program__fd(prog);
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@ -1,5 +1,8 @@
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// SPDX-License-Identifier: GPL-2.0
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#include <test_progs.h>
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#include <error.h>
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#include <linux/if.h>
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#include <linux/if_tun.h>
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#define CHECK_FLOW_KEYS(desc, got, expected) \
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CHECK_ATTR(memcmp(&got, &expected, sizeof(got)) != 0, \
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@ -140,13 +143,73 @@ struct test tests[] = {
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},
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};
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static int create_tap(const char *ifname)
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{
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struct ifreq ifr = {
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.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_NAPI | IFF_NAPI_FRAGS,
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};
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int fd, ret;
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strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
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fd = open("/dev/net/tun", O_RDWR);
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if (fd < 0)
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return -1;
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ret = ioctl(fd, TUNSETIFF, &ifr);
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if (ret)
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return -1;
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return fd;
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}
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static int tx_tap(int fd, void *pkt, size_t len)
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{
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struct iovec iov[] = {
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{
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.iov_len = len,
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.iov_base = pkt,
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},
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};
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return writev(fd, iov, ARRAY_SIZE(iov));
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}
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static int ifup(const char *ifname)
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{
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struct ifreq ifr = {};
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int sk, ret;
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strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
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sk = socket(PF_INET, SOCK_DGRAM, 0);
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if (sk < 0)
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return -1;
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ret = ioctl(sk, SIOCGIFFLAGS, &ifr);
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if (ret) {
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close(sk);
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return -1;
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}
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ifr.ifr_flags |= IFF_UP;
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ret = ioctl(sk, SIOCSIFFLAGS, &ifr);
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if (ret) {
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close(sk);
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return -1;
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}
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close(sk);
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return 0;
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}
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void test_flow_dissector(void)
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{
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int i, err, prog_fd, keys_fd = -1, tap_fd;
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struct bpf_object *obj;
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int i, err, prog_fd;
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__u32 duration = 0;
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err = bpf_flow_load(&obj, "./bpf_flow.o", "flow_dissector",
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"jmp_table", &prog_fd);
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"jmp_table", "last_dissection", &prog_fd, &keys_fd);
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if (err) {
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error_cnt++;
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return;
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@ -171,5 +234,40 @@ void test_flow_dissector(void)
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CHECK_FLOW_KEYS(tests[i].name, flow_keys, tests[i].keys);
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}
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/* Do the same tests but for skb-less flow dissector.
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* We use a known path in the net/tun driver that calls
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* eth_get_headlen and we manually export bpf_flow_keys
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* via BPF map in this case.
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*
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* Note, that since eth_get_headlen operates on a L2 level,
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* we adjust exported nhoff/thoff by ETH_HLEN.
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*/
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err = bpf_prog_attach(prog_fd, 0, BPF_FLOW_DISSECTOR, 0);
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CHECK(err, "bpf_prog_attach", "err %d errno %d", err, errno);
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tap_fd = create_tap("tap0");
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CHECK(tap_fd < 0, "create_tap", "tap_fd %d errno %d", tap_fd, errno);
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err = ifup("tap0");
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CHECK(err, "ifup", "err %d errno %d", err, errno);
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for (i = 0; i < ARRAY_SIZE(tests); i++) {
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struct bpf_flow_keys flow_keys = {};
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struct bpf_prog_test_run_attr tattr = {};
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__u32 key = 0;
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err = tx_tap(tap_fd, &tests[i].pkt, sizeof(tests[i].pkt));
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CHECK(err < 0, "tx_tap", "err %d errno %d", err, errno);
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err = bpf_map_lookup_elem(keys_fd, &key, &flow_keys);
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CHECK_ATTR(err, tests[i].name, "bpf_map_lookup_elem %d\n", err);
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flow_keys.nhoff -= ETH_HLEN;
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flow_keys.thoff -= ETH_HLEN;
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CHECK_ATTR(err, tests[i].name, "skb-less err %d\n", err);
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CHECK_FLOW_KEYS(tests[i].name, flow_keys, tests[i].keys);
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}
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bpf_object__close(obj);
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}
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@ -64,6 +64,25 @@ struct bpf_map_def SEC("maps") jmp_table = {
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.max_entries = 8
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};
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struct bpf_map_def SEC("maps") last_dissection = {
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.type = BPF_MAP_TYPE_ARRAY,
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.key_size = sizeof(__u32),
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.value_size = sizeof(struct bpf_flow_keys),
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.max_entries = 1,
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};
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static __always_inline int export_flow_keys(struct bpf_flow_keys *keys,
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int ret)
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{
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struct bpf_flow_keys *val;
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__u32 key = 0;
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val = bpf_map_lookup_elem(&last_dissection, &key);
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if (val)
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memcpy(val, keys, sizeof(*val));
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return ret;
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}
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static __always_inline void *bpf_flow_dissect_get_header(struct __sk_buff *skb,
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__u16 hdr_size,
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void *buffer)
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@ -109,10 +128,10 @@ static __always_inline int parse_eth_proto(struct __sk_buff *skb, __be16 proto)
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break;
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default:
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/* Protocol not supported */
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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}
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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}
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SEC("flow_dissector")
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@ -139,8 +158,8 @@ static __always_inline int parse_ip_proto(struct __sk_buff *skb, __u8 proto)
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case IPPROTO_ICMP:
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icmp = bpf_flow_dissect_get_header(skb, sizeof(*icmp), &_icmp);
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if (!icmp)
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return BPF_DROP;
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return BPF_OK;
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return export_flow_keys(keys, BPF_DROP);
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return export_flow_keys(keys, BPF_OK);
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case IPPROTO_IPIP:
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keys->is_encap = true;
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return parse_eth_proto(skb, bpf_htons(ETH_P_IP));
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@ -150,11 +169,11 @@ static __always_inline int parse_ip_proto(struct __sk_buff *skb, __u8 proto)
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case IPPROTO_GRE:
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gre = bpf_flow_dissect_get_header(skb, sizeof(*gre), &_gre);
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if (!gre)
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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if (bpf_htons(gre->flags & GRE_VERSION))
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/* Only inspect standard GRE packets with version 0 */
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return BPF_OK;
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return export_flow_keys(keys, BPF_OK);
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keys->thoff += sizeof(*gre); /* Step over GRE Flags and Proto */
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if (GRE_IS_CSUM(gre->flags))
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@ -170,7 +189,7 @@ static __always_inline int parse_ip_proto(struct __sk_buff *skb, __u8 proto)
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eth = bpf_flow_dissect_get_header(skb, sizeof(*eth),
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&_eth);
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if (!eth)
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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keys->thoff += sizeof(*eth);
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@ -181,31 +200,31 @@ static __always_inline int parse_ip_proto(struct __sk_buff *skb, __u8 proto)
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case IPPROTO_TCP:
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tcp = bpf_flow_dissect_get_header(skb, sizeof(*tcp), &_tcp);
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if (!tcp)
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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if (tcp->doff < 5)
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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if ((__u8 *)tcp + (tcp->doff << 2) > data_end)
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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keys->sport = tcp->source;
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keys->dport = tcp->dest;
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return BPF_OK;
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return export_flow_keys(keys, BPF_OK);
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case IPPROTO_UDP:
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case IPPROTO_UDPLITE:
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udp = bpf_flow_dissect_get_header(skb, sizeof(*udp), &_udp);
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if (!udp)
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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keys->sport = udp->source;
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keys->dport = udp->dest;
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return BPF_OK;
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return export_flow_keys(keys, BPF_OK);
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default:
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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}
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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}
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static __always_inline int parse_ipv6_proto(struct __sk_buff *skb, __u8 nexthdr)
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@ -225,7 +244,7 @@ static __always_inline int parse_ipv6_proto(struct __sk_buff *skb, __u8 nexthdr)
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return parse_ip_proto(skb, nexthdr);
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}
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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}
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PROG(IP)(struct __sk_buff *skb)
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@ -238,11 +257,11 @@ PROG(IP)(struct __sk_buff *skb)
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iph = bpf_flow_dissect_get_header(skb, sizeof(*iph), &_iph);
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if (!iph)
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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/* IP header cannot be smaller than 20 bytes */
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if (iph->ihl < 5)
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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keys->addr_proto = ETH_P_IP;
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keys->ipv4_src = iph->saddr;
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@ -250,7 +269,7 @@ PROG(IP)(struct __sk_buff *skb)
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keys->thoff += iph->ihl << 2;
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if (data + keys->thoff > data_end)
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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if (iph->frag_off & bpf_htons(IP_MF | IP_OFFSET)) {
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keys->is_frag = true;
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@ -264,7 +283,7 @@ PROG(IP)(struct __sk_buff *skb)
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}
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if (done)
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return BPF_OK;
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return export_flow_keys(keys, BPF_OK);
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return parse_ip_proto(skb, iph->protocol);
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}
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@ -276,7 +295,7 @@ PROG(IPV6)(struct __sk_buff *skb)
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ip6h = bpf_flow_dissect_get_header(skb, sizeof(*ip6h), &_ip6h);
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if (!ip6h)
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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keys->addr_proto = ETH_P_IPV6;
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memcpy(&keys->ipv6_src, &ip6h->saddr, 2*sizeof(ip6h->saddr));
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@ -288,11 +307,12 @@ PROG(IPV6)(struct __sk_buff *skb)
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PROG(IPV6OP)(struct __sk_buff *skb)
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{
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struct bpf_flow_keys *keys = skb->flow_keys;
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struct ipv6_opt_hdr *ip6h, _ip6h;
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ip6h = bpf_flow_dissect_get_header(skb, sizeof(*ip6h), &_ip6h);
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if (!ip6h)
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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/* hlen is in 8-octets and does not include the first 8 bytes
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* of the header
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@ -309,7 +329,7 @@ PROG(IPV6FR)(struct __sk_buff *skb)
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fragh = bpf_flow_dissect_get_header(skb, sizeof(*fragh), &_fragh);
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if (!fragh)
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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keys->thoff += sizeof(*fragh);
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keys->is_frag = true;
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@ -321,13 +341,14 @@ PROG(IPV6FR)(struct __sk_buff *skb)
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PROG(MPLS)(struct __sk_buff *skb)
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{
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struct bpf_flow_keys *keys = skb->flow_keys;
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struct mpls_label *mpls, _mpls;
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mpls = bpf_flow_dissect_get_header(skb, sizeof(*mpls), &_mpls);
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if (!mpls)
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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return BPF_OK;
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return export_flow_keys(keys, BPF_OK);
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}
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PROG(VLAN)(struct __sk_buff *skb)
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@ -339,10 +360,10 @@ PROG(VLAN)(struct __sk_buff *skb)
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if (keys->n_proto == bpf_htons(ETH_P_8021AD)) {
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vlan = bpf_flow_dissect_get_header(skb, sizeof(*vlan), &_vlan);
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if (!vlan)
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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if (vlan->h_vlan_encapsulated_proto != bpf_htons(ETH_P_8021Q))
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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keys->nhoff += sizeof(*vlan);
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keys->thoff += sizeof(*vlan);
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@ -350,14 +371,14 @@ PROG(VLAN)(struct __sk_buff *skb)
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vlan = bpf_flow_dissect_get_header(skb, sizeof(*vlan), &_vlan);
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if (!vlan)
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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keys->nhoff += sizeof(*vlan);
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keys->thoff += sizeof(*vlan);
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/* Only allow 8021AD + 8021Q double tagging and no triple tagging.*/
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if (vlan->h_vlan_encapsulated_proto == bpf_htons(ETH_P_8021AD) ||
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vlan->h_vlan_encapsulated_proto == bpf_htons(ETH_P_8021Q))
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return BPF_DROP;
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return export_flow_keys(keys, BPF_DROP);
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keys->n_proto = vlan->h_vlan_encapsulated_proto;
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return parse_eth_proto(skb, vlan->h_vlan_encapsulated_proto);
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