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bpf, selftests: Test BPF_FLOW_DISSECTOR_CONTINUE

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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
This commit is contained in:
Shmulik Ladkani 2022-08-21 14:35:19 +03:00 • committed by Daniel Borkmann
parent 5deedfbee8
commit d6513727c2
3 changed files with 44 additions and 0 deletions
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21
tools/testing/selftests/bpf/prog_tests/flow_dissector.c
View file

@ -8,6 +8,8 @@
#include "bpf_flow.skel.h" #include "bpf_flow.skel.h"
#define FLOW_CONTINUE_SADDR 0x7f00007f /* 127.0.0.127 */
#ifndef IP_MF #ifndef IP_MF
#define IP_MF 0x2000 #define IP_MF 0x2000
#endif #endif
@ -400,6 +402,25 @@ struct test tests[] = {
.flags = BPF_FLOW_DISSECTOR_F_STOP_AT_ENCAP, .flags = BPF_FLOW_DISSECTOR_F_STOP_AT_ENCAP,
.retval = BPF_OK, .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) static int create_tap(const char *ifname)

15
tools/testing/selftests/bpf/progs/bpf_flow.c
View file

@ -22,6 +22,8 @@
#define PROG(F) PROG_(F, _##F) #define PROG(F) PROG_(F, _##F)
#define PROG_(NUM, NAME) SEC("flow_dissector") int flow_dissector_##NUM #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 /* 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 * 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. * 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; 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); return parse_eth_proto(skb, keys->n_proto);
} }

8
tools/testing/selftests/bpf/test_flow_dissector.sh
View file

@ -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. # Send 10 IPv4/UDP packets from port 10. Filter should not drop any.
./test_flow_dissector -i 4 -f 10 ./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..." echo "Testing IPIP..."
# Send 10 IPv4/IPv4/UDP packets from port 8. Filter should not drop any. # 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 \ ./with_addr.sh ./with_tunnels.sh ./test_flow_dissector -o 4 -e bare -i 4 \