| Message ID | 20241114-flow_dissector-v2-11-ee4a3be3de65@bootlin.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | selftests/bpf: migrate test_flow_dissector.sh to test_progs | expand |
On 11/14, Alexis Lothoré (eBPF Foundation) wrote: > network_helpers.c provides some helpers to generate ip checksums or ip > pseudo-header checksums, but not for upper layers (eg: udp checksums) > > Add helpers for udp checksum to allow manually building udp packets. > > Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com> > --- > Changes in v2: > - new patch > --- > tools/testing/selftests/bpf/network_helpers.h | 27 +++++++++++++++++++++++++++ > 1 file changed, 27 insertions(+) > > diff --git a/tools/testing/selftests/bpf/network_helpers.h b/tools/testing/selftests/bpf/network_helpers.h > index 6d1ae56080c56a65c437899c32566f0e4c496c33..fa82269f7a169a518ba210fa8641eba02f262333 100644 > --- a/tools/testing/selftests/bpf/network_helpers.h > +++ b/tools/testing/selftests/bpf/network_helpers.h > @@ -161,6 +161,33 @@ build_ipv6_pseudo_header_csum(const struct in6_addr *saddr, > return csum_fold((__u32)s); > } > > +static inline __sum16 build_udp_v4_csum(const struct iphdr *iph, __u8 l4_proto, > + __u16 l4_len, const void *l4_start, > + int num_words) > +{ > + unsigned long pseudo_sum; > + int num_u16 = sizeof(iph->saddr); /* halfwords: twice byte len */ > + > + pseudo_sum = add_csum_hword((void *)&iph->saddr, num_u16); > + pseudo_sum += htons(l4_proto); > + pseudo_sum += l4_len; > + pseudo_sum += add_csum_hword(l4_start, num_words); > + return csum_fold(pseudo_sum); I was expecting to see a call to csum_tcpudp_magic here. And csum_ipv6_magic down below. These build pseudo header csum, so no need to manually do it again. > +} > + > +static inline __sum16 build_udp_v6_csum(const struct ipv6hdr *ip6h, > + const void *l4_start, int num_words) > +{ > + unsigned long pseudo_sum; > + int num_u16 = sizeof(ip6h->saddr); /* halfwords: twice byte len */ > + > + pseudo_sum = add_csum_hword((void *)&ip6h->saddr, num_u16); > + pseudo_sum += htons(ip6h->nexthdr); > + pseudo_sum += ip6h->payload_len; > + pseudo_sum += add_csum_hword(l4_start, num_words); > + return csum_fold(pseudo_sum); > +} > + > struct tmonitor_ctx; > > #ifdef TRAFFIC_MONITOR > > -- > 2.47.0 >
On 11/15/24 16:54, Stanislav Fomichev wrote: > On 11/14, Alexis Lothoré (eBPF Foundation) wrote: >> +static inline __sum16 build_udp_v4_csum(const struct iphdr *iph, __u8 l4_proto, >> + __u16 l4_len, const void *l4_start, >> + int num_words) >> +{ >> + unsigned long pseudo_sum; >> + int num_u16 = sizeof(iph->saddr); /* halfwords: twice byte len */ >> + >> + pseudo_sum = add_csum_hword((void *)&iph->saddr, num_u16); >> + pseudo_sum += htons(l4_proto); >> + pseudo_sum += l4_len; >> + pseudo_sum += add_csum_hword(l4_start, num_words); >> + return csum_fold(pseudo_sum); > > I was expecting to see a call to csum_tcpudp_magic here. And csum_ipv6_magic > down below. These build pseudo header csum, so no need to manually do it > again. I initially tried to fit csum_tcpudp_magic here and did not manage to make a valid UDP checksum, but after more attempts, it looks like I had a misunderstanding this checksum computation. I am now able to used csum_tcpudp_magic in build_udp_v4_csum, it will be fixed in the next revision :) Thanks, Alexis
diff --git a/tools/testing/selftests/bpf/network_helpers.h b/tools/testing/selftests/bpf/network_helpers.h index 6d1ae56080c56a65c437899c32566f0e4c496c33..fa82269f7a169a518ba210fa8641eba02f262333 100644 --- a/tools/testing/selftests/bpf/network_helpers.h +++ b/tools/testing/selftests/bpf/network_helpers.h @@ -161,6 +161,33 @@ build_ipv6_pseudo_header_csum(const struct in6_addr *saddr, return csum_fold((__u32)s); } +static inline __sum16 build_udp_v4_csum(const struct iphdr *iph, __u8 l4_proto, + __u16 l4_len, const void *l4_start, + int num_words) +{ + unsigned long pseudo_sum; + int num_u16 = sizeof(iph->saddr); /* halfwords: twice byte len */ + + pseudo_sum = add_csum_hword((void *)&iph->saddr, num_u16); + pseudo_sum += htons(l4_proto); + pseudo_sum += l4_len; + pseudo_sum += add_csum_hword(l4_start, num_words); + return csum_fold(pseudo_sum); +} + +static inline __sum16 build_udp_v6_csum(const struct ipv6hdr *ip6h, + const void *l4_start, int num_words) +{ + unsigned long pseudo_sum; + int num_u16 = sizeof(ip6h->saddr); /* halfwords: twice byte len */ + + pseudo_sum = add_csum_hword((void *)&ip6h->saddr, num_u16); + pseudo_sum += htons(ip6h->nexthdr); + pseudo_sum += ip6h->payload_len; + pseudo_sum += add_csum_hword(l4_start, num_words); + return csum_fold(pseudo_sum); +} + struct tmonitor_ctx; #ifdef TRAFFIC_MONITOR
network_helpers.c provides some helpers to generate ip checksums or ip pseudo-header checksums, but not for upper layers (eg: udp checksums) Add helpers for udp checksum to allow manually building udp packets. Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com> --- Changes in v2: - new patch --- tools/testing/selftests/bpf/network_helpers.h | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+)