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@xxxxxxxxx>
---
.../selftests/bpf/prog_tests/flow_dissector.c | 21 +++++++++++++++++++
tools/testing/selftests/bpf/progs/bpf_flow.c | 15 +++++++++++++
.../selftests/bpf/test_flow_dissector.sh | 8 +++++++
3 files changed, 44 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/flow_dissector.c b/tools/testing/selftests/bpf/prog_tests/flow_dissector.c
index 8fa3c454995e..7acca37a3d2b 100644
--- a/tools/testing/selftests/bpf/prog_tests/flow_dissector.c
+++ b/tools/testing/selftests/bpf/prog_tests/flow_dissector.c
@@ -8,6 +8,8 @@
#include "bpf_flow.skel.h"
+#define FLOW_CONTINUE_SADDR 0x7f00007f /* 127.0.0.127 */
+
#ifndef IP_MF
#define IP_MF 0x2000
#endif
@@ -400,6 +402,25 @@ struct test tests[] = {
.flags = BPF_FLOW_DISSECTOR_F_STOP_AT_ENCAP,
.retval = BPF_OK,
},
+ {
+ .name = "ipip-encap-dissector-continue",
+ .pkt.ipip = {
+ .eth.h_proto = __bpf_constant_htons(ETH_P_IP),
+ .iph.ihl = 5,
+ .iph.protocol = IPPROTO_IPIP,
+ .iph.tot_len = __bpf_constant_htons(MAGIC_BYTES),
+ .iph.saddr = __bpf_constant_htonl(FLOW_CONTINUE_SADDR),
+ .iph_inner.ihl = 5,
+ .iph_inner.protocol = IPPROTO_TCP,
+ .iph_inner.tot_len =
+ __bpf_constant_htons(MAGIC_BYTES) -
+ sizeof(struct iphdr),
+ .tcp.doff = 5,
+ .tcp.source = 99,
+ .tcp.dest = 9090,
+ },
+ .retval = BPF_FLOW_DISSECTOR_CONTINUE,
+ },
};
static int create_tap(const char *ifname)
diff --git a/tools/testing/selftests/bpf/progs/bpf_flow.c b/tools/testing/selftests/bpf/progs/bpf_flow.c
index f266c757b3df..a20c5ed5e454 100644
--- a/tools/testing/selftests/bpf/progs/bpf_flow.c
+++ b/tools/testing/selftests/bpf/progs/bpf_flow.c
@@ -22,6 +22,8 @@
#define PROG(F) PROG_(F, _##F)
#define PROG_(NUM, NAME) SEC("flow_dissector") int flow_dissector_##NUM
+#define FLOW_CONTINUE_SADDR 0x7f00007f /* 127.0.0.127 */
+
/* These are the identifiers of the BPF programs that will be used in tail
* calls. Name is limited to 16 characters, with the terminating character and
* bpf_func_ above, we have only 6 to work with, anything after will be cropped.
@@ -143,6 +145,19 @@ int _dissect(struct __sk_buff *skb)
{
struct bpf_flow_keys *keys = skb->flow_keys;
+ if (keys->n_proto == bpf_htons(ETH_P_IP)) {
+ /* IP traffic from FLOW_CONTINUE_SADDR falls-back to
+ * standard dissector
+ */
+ struct iphdr *iph, _iph;
+
+ iph = bpf_flow_dissect_get_header(skb, sizeof(*iph), &_iph);
+ if (iph && iph->ihl == 5 &&
+ iph->saddr == bpf_htonl(FLOW_CONTINUE_SADDR)) {
+ return BPF_FLOW_DISSECTOR_CONTINUE;
+ }
+ }
+
return parse_eth_proto(skb, keys->n_proto);
}
diff --git a/tools/testing/selftests/bpf/test_flow_dissector.sh b/tools/testing/selftests/bpf/test_flow_dissector.sh
index dbd91221727d..5303ce0c977b 100755
--- a/tools/testing/selftests/bpf/test_flow_dissector.sh
+++ b/tools/testing/selftests/bpf/test_flow_dissector.sh
@@ -115,6 +115,14 @@ tc filter add dev lo parent ffff: protocol ip pref 1337 flower ip_proto \
# Send 10 IPv4/UDP packets from port 10. Filter should not drop any.
./test_flow_dissector -i 4 -f 10
+echo "Testing IPv4 from 127.0.0.127 (fallback to generic dissector)..."
+# Send 10 IPv4/UDP packets from port 8. Filter should not drop any.
+./test_flow_dissector -i 4 -S 127.0.0.127 -f 8
+# Send 10 IPv4/UDP packets from port 9. Filter should drop all.
+./test_flow_dissector -i 4 -S 127.0.0.127 -f 9 -F
+# Send 10 IPv4/UDP packets from port 10. Filter should not drop any.
+./test_flow_dissector -i 4 -S 127.0.0.127 -f 10
+
echo "Testing IPIP..."
# Send 10 IPv4/IPv4/UDP packets from port 8. Filter should not drop any.
./with_addr.sh ./with_tunnels.sh ./test_flow_dissector -o 4 -e bare -i 4 \
--
2.37.2
