• Marcelo Ricardo Leitner's avatar
    sctp: allow GSO frags to access the chunk too · 1f45f78f
    Marcelo Ricardo Leitner authored
    SCTP will try to access original IP headers on sctp_recvmsg in order to
    copy the addresses used. There are also other places that do similar access
    to IP or even SCTP headers. But after 90017acc ("sctp: Add GSO
    support") they aren't always there because they are only present in the
    header skb.
    SCTP handles the queueing of incoming data by cloning the incoming skb
    and limiting to only the relevant payload. This clone has its cb updated
    to something different and it's then queued on socket rx queue. Thus we
    need to fix this in two moments.
    For rx path, not related to socket queue yet, this patch uses a
    partially copied sctp_input_cb to such GSO frags. This restores the
    ability to access the headers for this part of the code.
    Regarding the socket rx queue, it removes iif member from sctp_event and
    also add a chunk pointer on it.
    With these changes we're always able to reach the headers again.
    The biggest change here is that now the sctp_chunk struct and the
    original skb are only freed after the application consumed the buffer.
    Note however that the original payload was already like this due to the
    skb cloning.
    For iif, SCTP's IPv4 code doesn't use it, so no change is necessary.
    IPv6 now can fetch it directly from original's IPv6 CB as the original
    skb is still accessible.
    In the future we probably can simplify sctp_v*_skb_iif() stuff, as
    sctp_v4_skb_iif() was called but it's return value not used, and now
    it's not even called, but such cleanup is out of scope for this change.
    Fixes: 90017acc
     ("sctp: Add GSO support")
    Signed-off-by: default avatarMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>