diff options
| author | Asbjørn Sloth Tønnesen <ast@fiberby.net> | 2024-08-08 07:59:02 +0000 |
|---|---|---|
| committer | Martin KaFai Lau <martin.lau@kernel.org> | 2024-08-13 16:43:15 -0700 |
| commit | 92ec8b9367ab328cdd3d4409464137bc9775a2e5 (patch) | |
| tree | 63b767ecbc6273cc99d36a57fc72bbd3638e0578 /tools/testing/selftests/bpf/prog_tests/flow_dissector.c | |
| parent | 39e8111ce5ce76039a80eaf6dd71ae8bb6866f95 (diff) | |
selftests/bpf: Avoid subtraction after htons() in ipip tests
On little-endian systems, doing subtraction after htons()
leads to interesting results:
Given:
MAGIC_BYTES = 123 = 0x007B aka. in big endian: 0x7B00 = 31488
sizeof(struct iphdr) = 20
Before this patch:
__bpf_constant_htons(MAGIC_BYTES) - sizeof(struct iphdr) = 0x7AEC
0x7AEC = htons(0xEC7A) = htons(60538)
So these were outer IP packets with a total length of 123 bytes,
containing an inner IP packet with a total length of 60538 bytes.
After this patch:
__bpf_constant_htons(MAGIC_BYTES - sizeof(struct iphdr)) = htons(103)
Now these packets are outer IP packets with a total length of 123 bytes,
containing an inner IP packet with a total length of 103 bytes.
Signed-off-by: Asbjørn Sloth Tønnesen <ast@fiberby.net>
Reviewed-by: Toke Høiland-Jørgensen <toke@kernel.org>
Link: https://lore.kernel.org/r/20240808075906.1849564-1-ast@fiberby.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Diffstat (limited to 'tools/testing/selftests/bpf/prog_tests/flow_dissector.c')
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/flow_dissector.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/flow_dissector.c b/tools/testing/selftests/bpf/prog_tests/flow_dissector.c index 9e5f38739104..6b3078dd5645 100644 --- a/tools/testing/selftests/bpf/prog_tests/flow_dissector.c +++ b/tools/testing/selftests/bpf/prog_tests/flow_dissector.c @@ -378,8 +378,8 @@ struct test tests[] = { .iph_inner.ihl = 5, .iph_inner.protocol = IPPROTO_TCP, .iph_inner.tot_len = - __bpf_constant_htons(MAGIC_BYTES) - - sizeof(struct iphdr), + __bpf_constant_htons(MAGIC_BYTES - + sizeof(struct iphdr)), .tcp.doff = 5, .tcp.source = 80, .tcp.dest = 8080, @@ -407,8 +407,8 @@ struct test tests[] = { .iph_inner.ihl = 5, .iph_inner.protocol = IPPROTO_TCP, .iph_inner.tot_len = - __bpf_constant_htons(MAGIC_BYTES) - - sizeof(struct iphdr), + __bpf_constant_htons(MAGIC_BYTES - + sizeof(struct iphdr)), .tcp.doff = 5, .tcp.source = 80, .tcp.dest = 8080, @@ -436,8 +436,8 @@ struct test tests[] = { .iph_inner.ihl = 5, .iph_inner.protocol = IPPROTO_TCP, .iph_inner.tot_len = - __bpf_constant_htons(MAGIC_BYTES) - - sizeof(struct iphdr), + __bpf_constant_htons(MAGIC_BYTES - + sizeof(struct iphdr)), .tcp.doff = 5, .tcp.source = 99, .tcp.dest = 9090, |