• Hangbin Liu's avatar
    IPv6: reply ICMP error if the first fragment don't include all headers · 2efdaaaf
    Hangbin Liu authored
    Based on RFC 8200, Section 4.5 Fragment Header:
    
      -  If the first fragment does not include all headers through an
         Upper-Layer header, then that fragment should be discarded and
         an ICMP Parameter Problem, Code 3, message should be sent to
         the source of the fragment, with the Pointer field set to zero.
    
    Checking each packet header in IPv6 fast path will have performance impact,
    so I put the checking in ipv6_frag_rcv().
    
    As the packet may be any kind of L4 protocol, I only checked some common
    protocols' header length and handle others by (offset + 1) > skb->len.
    Also use !(frag_off & htons(IP6_OFFSET)) to catch atomic fragments
    (fragmented packet with only one fragment).
    
    When send ICMP error message, if the 1st truncated fragment is ICMP message,
    icmp6_send() will break as is_ineligible() return true. So I added a check
    in is_ineligible() to let fragment packet with nexthdr ICMP but no ICMP header
    return false.
    Signed-off-by: default avatarHangbin Liu <liuhangbin@gmail.com>
    Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
    2efdaaaf
reassembly.c 15.1 KB