bpf, selftests: Test BPF_FLOW_DISSECTOR_CONTINUE
The dissector program returns BPF_FLOW_DISSECTOR_CONTINUE (and avoids setting skb->flow_keys or last_dissection map) in case it encounters IP packets whose (outer) source address is 127.0.0.127. Additional test is added to prog_tests/flow_dissector.c which sets this address as test's pkk.iph.saddr, with the expected retval of BPF_FLOW_DISSECTOR_CONTINUE. Also, legacy test_flow_dissector.sh was similarly augmented. Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Stanislav Fomichev <sdf@google.com> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20220821113519.116765-5-shmulik.ladkani@gmail.com
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@ -8,6 +8,8 @@
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#include "bpf_flow.skel.h"
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#define FLOW_CONTINUE_SADDR 0x7f00007f /* 127.0.0.127 */
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#ifndef IP_MF
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#define IP_MF 0x2000
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#endif
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@ -400,6 +402,25 @@ struct test tests[] = {
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.flags = BPF_FLOW_DISSECTOR_F_STOP_AT_ENCAP,
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.retval = BPF_OK,
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},
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{
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.name = "ipip-encap-dissector-continue",
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.pkt.ipip = {
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.eth.h_proto = __bpf_constant_htons(ETH_P_IP),
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.iph.ihl = 5,
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.iph.protocol = IPPROTO_IPIP,
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.iph.tot_len = __bpf_constant_htons(MAGIC_BYTES),
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.iph.saddr = __bpf_constant_htonl(FLOW_CONTINUE_SADDR),
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.iph_inner.ihl = 5,
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.iph_inner.protocol = IPPROTO_TCP,
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.iph_inner.tot_len =
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__bpf_constant_htons(MAGIC_BYTES) -
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sizeof(struct iphdr),
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.tcp.doff = 5,
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.tcp.source = 99,
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.tcp.dest = 9090,
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},
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.retval = BPF_FLOW_DISSECTOR_CONTINUE,
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},
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};
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static int create_tap(const char *ifname)
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@ -22,6 +22,8 @@
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#define PROG(F) PROG_(F, _##F)
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#define PROG_(NUM, NAME) SEC("flow_dissector") int flow_dissector_##NUM
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#define FLOW_CONTINUE_SADDR 0x7f00007f /* 127.0.0.127 */
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/* These are the identifiers of the BPF programs that will be used in tail
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* calls. Name is limited to 16 characters, with the terminating character and
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* bpf_func_ above, we have only 6 to work with, anything after will be cropped.
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@ -143,6 +145,19 @@ int _dissect(struct __sk_buff *skb)
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{
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struct bpf_flow_keys *keys = skb->flow_keys;
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if (keys->n_proto == bpf_htons(ETH_P_IP)) {
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/* IP traffic from FLOW_CONTINUE_SADDR falls-back to
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* standard dissector
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*/
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struct iphdr *iph, _iph;
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iph = bpf_flow_dissect_get_header(skb, sizeof(*iph), &_iph);
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if (iph && iph->ihl == 5 &&
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iph->saddr == bpf_htonl(FLOW_CONTINUE_SADDR)) {
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return BPF_FLOW_DISSECTOR_CONTINUE;
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}
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}
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return parse_eth_proto(skb, keys->n_proto);
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}
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@ -115,6 +115,14 @@ tc filter add dev lo parent ffff: protocol ip pref 1337 flower ip_proto \
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# Send 10 IPv4/UDP packets from port 10. Filter should not drop any.
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./test_flow_dissector -i 4 -f 10
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echo "Testing IPv4 from 127.0.0.127 (fallback to generic dissector)..."
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# Send 10 IPv4/UDP packets from port 8. Filter should not drop any.
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./test_flow_dissector -i 4 -S 127.0.0.127 -f 8
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# Send 10 IPv4/UDP packets from port 9. Filter should drop all.
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./test_flow_dissector -i 4 -S 127.0.0.127 -f 9 -F
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# Send 10 IPv4/UDP packets from port 10. Filter should not drop any.
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./test_flow_dissector -i 4 -S 127.0.0.127 -f 10
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echo "Testing IPIP..."
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# Send 10 IPv4/IPv4/UDP packets from port 8. Filter should not drop any.
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./with_addr.sh ./with_tunnels.sh ./test_flow_dissector -o 4 -e bare -i 4 \
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