1. 25 Jun, 2019 2 commits
    • Eric Dumazet's avatar
      UBUNTU: SAUCE: tcp: enforce tcp_min_snd_mss in tcp_mtu_probing() · 42f4a152
      Eric Dumazet authored
      If mtu probing is enabled tcp_mtu_probing() could very well end up
      with a too small MSS.
      
      Use the new sysctl tcp_min_snd_mss to make sure MSS search
      is performed in an acceptable range.
      Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
      Reported-by: default avatarJonathan Lemon <jonathan.lemon@gmail.com>
      Cc: Jonathan Looney <jtl@netflix.com>
      Cc: Neal Cardwell <ncardwell@google.com>
      Cc: Yuchung Cheng <ycheng@google.com>
      Cc: Tyler Hicks <tyhicks@canonical.com>
      Cc: Bruce Curtis <brucec@netflix.com>
      
      CVE-2019-11479
      
      [tyhicks: Minor context changes due to missing cleanup commit
       d0f36847 ("tcp: tcp_mtu_probing() cleanup")]
      Signed-off-by: default avatarTyler Hicks <tyhicks@canonical.com>
      Signed-off-by: default avatarStefan Bader <stefan.bader@canonical.com>
      42f4a152
    • Eric Dumazet's avatar
      UBUNTU: SAUCE: tcp: add tcp_min_snd_mss sysctl · cbe4fe47
      Eric Dumazet authored
      Some TCP peers announce a very small MSS option in their SYN and/or
      SYN/ACK messages.
      
      This forces the stack to send packets with a very high network/cpu
      overhead.
      
      Linux has enforced a minimal value of 48. Since this value includes
      the size of TCP options, and that the options can consume up to 40
      bytes, this means that each segment can include only 8 bytes of payload.
      
      In some cases, it can be useful to increase the minimal value
      to a saner value.
      
      We still let the default to 48 (TCP_MIN_SND_MSS), for compatibility
      reasons.
      
      Note that TCP_MAXSEG socket option enforces a minimal value
      of (TCP_MIN_MSS). David Miller increased this minimal value
      in commit c39508d6 ("tcp: Make TCP_MAXSEG minimum more correct.")
      from 64 to 88.
      
      We might in the future merge TCP_MIN_SND_MSS and TCP_MIN_MSS.
      Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
      Suggested-by: default avatarJonathan Looney <jtl@netflix.com>
      Cc: Neal Cardwell <ncardwell@google.com>
      Cc: Yuchung Cheng <ycheng@google.com>
      Cc: Tyler Hicks <tyhicks@canonical.com>
      Cc: Bruce Curtis <brucec@netflix.com>
      Cc: Jonathan Lemon <jonathan.lemon@gmail.com>
      
      CVE-2019-11479
      
      [tyhicks: Minor context adjustments in ipv4.h and sysctl_net_ipv4.c]
      Signed-off-by: default avatarTyler Hicks <tyhicks@canonical.com>
      Signed-off-by: default avatarStefan Bader <stefan.bader@canonical.com>
      cbe4fe47
  2. 11 Jun, 2019 2 commits
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