In real world production websites, the IP_DF flag is not always set for each packet from these websites. the IP_DF flag check breaks Internet connection to these websites for home based firewall like BPFire when XDP synproxy program is attached to firewall Internet facing side interface. see [0] [0] https://github.com/vincentmli/BPFire/issues/59 Signed-off-by: Vincent Li <vincent.mc.li@xxxxxxxxx> --- tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c b/tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c index f8f5dc9f72b8..62b8e29ced9f 100644 --- a/tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c +++ b/tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c @@ -21,7 +21,6 @@ #define tcp_flag_word(tp) (((union tcp_word_hdr *)(tp))->words[3]) -#define IP_DF 0x4000 #define IP_MF 0x2000 #define IP_OFFSET 0x1fff @@ -442,7 +441,7 @@ static __always_inline int tcp_lookup(void *ctx, struct header_pointers *hdr, bo /* TCP doesn't normally use fragments, and XDP can't reassemble * them. */ - if ((hdr->ipv4->frag_off & bpf_htons(IP_DF | IP_MF | IP_OFFSET)) != bpf_htons(IP_DF)) + if ((hdr->ipv4->frag_off & bpf_htons(IP_MF | IP_OFFSET)) != 0) return XDP_DROP; tup.ipv4.saddr = hdr->ipv4->saddr; -- 2.34.1
