1. 13 Nov, 2014 2 commits
    • Daniel Borkmann's avatar
      net: sctp: fix skb_over_panic when receiving malformed ASCONF chunks · 240432f9
      Daniel Borkmann authored
      commit 9de7922b upstream.
      
      Commit 6f4c618d ("SCTP : Add paramters validity check for
      ASCONF chunk") added basic verification of ASCONF chunks, however,
      it is still possible to remotely crash a server by sending a
      special crafted ASCONF chunk, even up to pre 2.6.12 kernels:
      
      skb_over_panic: text:ffffffffa01ea1c3 len:31056 put:30768
       head:ffff88011bd81800 data:ffff88011bd81800 tail:0x7950
       end:0x440 dev:<NULL>
       ------------[ cut here ]------------
      kernel BUG at net/core/skbuff.c:129!
      [...]
      Call Trace:
       <IRQ>
       [<ffffffff8144fb1c>] skb_put+0x5c/0x70
       [<ffffffffa01ea1c3>] sctp_addto_chunk+0x63/0xd0 [sctp]
       [<ffffffffa01eadaf>] sctp_process_asconf+0x1af/0x540 [sctp]
       [<ffffffff8152d025>] ? _read_unlock_bh+0x15/0x20
       [<ffffffffa01e0038>] sctp_sf_do_asconf+0x168/0x240 [sctp]
       [<ffffffffa01e3751>] sctp_do_sm+0x71/0x1210 [sctp]
       [<ffffffff8147645d>] ? fib_rules_lookup+0xad/0xf0
       [<ffffffffa01e6b22>] ? sctp_cmp_addr_exact+0x32/0x40 [sctp]
       [<ffffffffa01e8393>] sctp_assoc_bh_rcv+0xd3/0x180 [sctp]
       [<ffffffffa01ee986>] sctp_inq_push+0x56/0x80 [sctp]
       [<ffffffffa01fcc42>] sctp_rcv+0x982/0xa10 [sctp]
       [<ffffffffa01d5123>] ? ipt_local_in_hook+0x23/0x28 [iptable_filter]
       [<ffffffff8148bdc9>] ? nf_iterate+0x69/0xb0
       [<ffffffff81496d10>] ? ip_local_deliver_finish+0x0/0x2d0
       [<ffffffff8148bf86>] ? nf_hook_slow+0x76/0x120
       [<ffffffff81496d10>] ? ip_local_deliver_finish+0x0/0x2d0
       [<ffffffff81496ded>] ip_local_deliver_finish+0xdd/0x2d0
       [<ffffffff81497078>] ip_local_deliver+0x98/0xa0
       [<ffffffff8149653d>] ip_rcv_finish+0x12d/0x440
       [<ffffffff81496ac5>] ip_rcv+0x275/0x350
       [<ffffffff8145c88b>] __netif_receive_skb+0x4ab/0x750
       [<ffffffff81460588>] netif_receive_skb+0x58/0x60
      
      This can be triggered e.g., through a simple scripted nmap
      connection scan injecting the chunk after the handshake, for
      example, ...
      
        -------------- INIT[ASCONF; ASCONF_ACK] ------------->
        <----------- INIT-ACK[ASCONF; ASCONF_ACK] ------------
        -------------------- COOKIE-ECHO -------------------->
        <-------------------- COOKIE-ACK ---------------------
        ------------------ ASCONF; UNKNOWN ------------------>
      
      ... where ASCONF chunk of length 280 contains 2 parameters ...
      
        1) Add IP address parameter (param length: 16)
        2) Add/del IP address parameter (param length: 255)
      
      ... followed by an UNKNOWN chunk of e.g. 4 bytes. Here, the
      Address Parameter in the ASCONF chunk is even missing, too.
      This is just an example and similarly-crafted ASCONF chunks
      could be used just as well.
      
      The ASCONF chunk passes through sctp_verify_asconf() as all
      parameters passed sanity checks, and after walking, we ended
      up successfully at the chunk end boundary, and thus may invoke
      sctp_process_asconf(). Parameter walking is done with
      WORD_ROUND() to take padding into account.
      
      In sctp_process_asconf()'s TLV processing, we may fail in
      sctp_process_asconf_param() e.g., due to removal of the IP
      address that is also the source address of the packet containing
      the ASCONF chunk, and thus we need to add all TLVs after the
      failure to our ASCONF response to remote via helper function
      sctp_add_asconf_response(), which basically invokes a
      sctp_addto_chunk() adding the error parameters to the given
      skb.
      
      When walking to the next parameter this time, we proceed
      with ...
      
        length = ntohs(asconf_param->param_hdr.length);
        asconf_param = (void *)asconf_param + length;
      
      ... instead of the WORD_ROUND()'ed length, thus resulting here
      in an off-by-one that leads to reading the follow-up garbage
      parameter length of 12336, and thus throwing an skb_over_panic
      for the reply when trying to sctp_addto_chunk() next time,
      which implicitly calls the skb_put() with that length.
      
      Fix it by using sctp_walk_params() [ which is also used in
      INIT parameter processing ] macro in the verification *and*
      in ASCONF processing: it will make sure we don't spill over,
      that we walk parameters WORD_ROUND()'ed. Moreover, we're being
      more defensive and guard against unknown parameter types and
      missized addresses.
      
      Joint work with Vlad Yasevich.
      
      Fixes: b896b82b ("[SCTP] ADDIP: Support for processing incoming ASCONF_ACK chunks.")
      Signed-off-by: default avatarDaniel Borkmann <dborkman@redhat.com>
      Signed-off-by: default avatarVlad Yasevich <vyasevich@gmail.com>
      Acked-by: default avatarNeil Horman <nhorman@tuxdriver.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
      240432f9
    • Ben Hutchings's avatar
      drivers/net: macvtap and tun depend on INET · 6b99e68d
      Ben Hutchings authored
      commit de11b0e8 upstream.
      
      These drivers now call ipv6_proxy_select_ident(), which is defined
      only if CONFIG_INET is enabled.  However, they have really depended
      on CONFIG_INET for as long as they have allowed sending GSO packets
      from userland.
      Reported-by: default avatarkbuild test robot <fengguang.wu@intel.com>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      Fixes: f43798c2 ("tun: Allow GSO using virtio_net_hdr")
      Fixes: b9fb9ee0 ("macvtap: add GSO/csum offload support")
      Fixes: 5188cd44 ("drivers/net, ipv6: Select IPv6 fragment idents for virtio UFO packets")
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
      6b99e68d
  2. 05 Nov, 2014 38 commits