• Andrew Lunn's avatar
    icmp: ICMPV6: Examine invoking packet for Segment Route Headers. · e4129440
    Andrew Lunn authored
    RFC8754 says:
    
    ICMP error packets generated within the SR domain are sent to source
    nodes within the SR domain.  The invoking packet in the ICMP error
    message may contain an SRH.  Since the destination address of a packet
    with an SRH changes as each segment is processed, it may not be the
    destination used by the socket or application that generated the
    invoking packet.
    
    For the source of an invoking packet to process the ICMP error
    message, the ultimate destination address of the IPv6 header may be
    required.  The following logic is used to determine the destination
    address for use by protocol-error handlers.
    
    *  Walk all extension headers of the invoking IPv6 packet to the
       routing extension header preceding the upper-layer header.
    
       -  If routing header is type 4 Segment Routing Header (SRH)
    
          o  The SID at Segment List[0] may be used as the destination
             address of the invoking packet.
    
    Mangle the skb so the network header points to the invoking packet
    inside the ICMP packet. The seg6 helpers can then be used on the skb
    to find any segment routing headers. If found, mark this fact in the
    IPv6 control block of the skb, and store the offset into the packet of
    the SRH. Then restore the skb back to its old state.
    Signed-off-by: default avatarAndrew Lunn <andrew@lunn.ch>
    Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
    Reviewed-by: default avatarWillem de Bruijn <willemb@google.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    e4129440
seg6.c 11.5 KB