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commitfbade4bd08upstream. The sockmap feature allows bpf syscall from userspace, or based on bpf sockops, replacing the sk_prot of sockets during protocol stack processing with sockmap's custom read/write interfaces. ''' tcp_rcv_state_process() subflow_syn_recv_sock() tcp_init_transfer(BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB) bpf_skops_established <== sockops bpf_sock_map_update(sk) <== call bpf helper tcp_bpf_update_proto() <== update sk_prot ''' Consider two scenarios: 1. When the server has MPTCP enabled and the client also requests MPTCP, the sk passed to the BPF program is a subflow sk. Since subflows only handle partial data, replacing their sk_prot is meaningless and will cause traffic disruption. 2. When the server has MPTCP enabled but the client sends a TCP SYN without MPTCP, subflow_syn_recv_sock() performs a fallback on the subflow, replacing the subflow sk's sk_prot with the native sk_prot. ''' subflow_ulp_fallback() subflow_drop_ctx() mptcp_subflow_ops_undo_override() ''' Subsequently, accept::mptcp_stream_accept::mptcp_fallback_tcp_ops() converts the subflow to plain TCP. For the first case, we should prevent it from being combined with sockmap by setting sk_prot->psock_update_sk_prot to NULL, which will be blocked by sockmap's own flow. For the second case, since subflow_syn_recv_sock() has already restored sk_prot to native tcp_prot/tcpv6_prot, no further action is needed. Fixes:cec37a6e41("mptcp: Handle MP_CAPABLE options for outgoing connections") Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev> Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Cc: <stable@vger.kernel.org> Link: https://patch.msgid.link/20251111060307.194196-2-jiayuan.chen@linux.dev Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2203 lines
62 KiB
2203 lines
62 KiB