Hi, I'm trying to perform some basic TCP MSS clamping with eBPF and it's being harder than expected: * Parsing TCP options can be challenging for the eBPF verifier as it's been shown in [1] by Christian Deacon. * bpf_store_hdr_opt() introduced in [2] doesn't seem to be useful here cause it refuses to overwrite an existing TCP option and MSS is already set when BPF_SOCK_OPS_WRITE_HDR_OPT_CB is triggered. * bpf_setsockopt() isn't able to set TCP_MAXSEG per [3]. Am I missing something? Thanks, Valentin Gutierrez [1] https://github.com/gamemann/XDP-TCP-Header-Options/ [2] https://lore.kernel.org/bpf/20200730205748.3354954-1-kafai@xxxxxx/T/ [3] https://github.com/torvalds/linux/blob/d2f51b3516dade79269ff45eae2a7668ae711b25/net/core/filter.c#L5151
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