1. 22 8月, 2016 12 次提交
    • A
      Add PKCS#12 UTF-8 interoperability test. · 70bf33d1
      Andy Polyakov 提交于
      Reviewed-by: NRichard Levitte <levitte@openssl.org>
      70bf33d1
    • A
      crypto/pkcs12: add UTF8 support. · 9e6b2f54
      Andy Polyakov 提交于
      Reviewed-by: NRichard Levitte <levitte@openssl.org>
      9e6b2f54
    • M
      Prevent DTLS Finished message injection · 5cb4d646
      Matt Caswell 提交于
      Follow on from CVE-2016-2179
      
      The investigation and analysis of CVE-2016-2179 highlighted a related flaw.
      
      This commit fixes a security "near miss" in the buffered message handling
      code. Ultimately this is not currently believed to be exploitable due to
      the reasons outlined below, and therefore there is no CVE for this on its
      own.
      
      The issue this commit fixes is a MITM attack where the attacker can inject
      a Finished message into the handshake. In the description below it is
      assumed that the attacker injects the Finished message for the server to
      receive it. The attack could work equally well the other way around (i.e
      where the client receives the injected Finished message).
      
      The MITM requires the following capabilities:
      - The ability to manipulate the MTU that the client selects such that it
      is small enough for the client to fragment Finished messages.
      - The ability to selectively drop and modify records sent from the client
      - The ability to inject its own records and send them to the server
      
      The MITM forces the client to select a small MTU such that the client
      will fragment the Finished message. Ideally for the attacker the first
      fragment will contain all but the last byte of the Finished message,
      with the second fragment containing the final byte.
      
      During the handshake and prior to the client sending the CCS the MITM
      injects a plaintext Finished message fragment to the server containing
      all but the final byte of the Finished message. The message sequence
      number should be the one expected to be used for the real Finished message.
      
      OpenSSL will recognise that the received fragment is for the future and
      will buffer it for later use.
      
      After the client sends the CCS it then sends its own Finished message in
      two fragments. The MITM causes the first of these fragments to be
      dropped. The OpenSSL server will then receive the second of the fragments
      and reassemble the complete Finished message consisting of the MITM
      fragment and the final byte from the real client.
      
      The advantage to the attacker in injecting a Finished message is that
      this provides the capability to modify other handshake messages (e.g.
      the ClientHello) undetected. A difficulty for the attacker is knowing in
      advance what impact any of those changes might have on the final byte of
      the handshake hash that is going to be sent in the "real" Finished
      message. In the worst case for the attacker this means that only 1 in
      256 of such injection attempts will succeed.
      
      It may be possible in some situations for the attacker to improve this such
      that all attempts succeed. For example if the handshake includes client
      authentication then the final message flight sent by the client will
      include a Certificate. Certificates are ASN.1 objects where the signed
      portion is DER encoded. The non-signed portion could be BER encoded and so
      the attacker could re-encode the certificate such that the hash for the
      whole handshake comes to a different value. The certificate re-encoding
      would not be detectable because only the non-signed portion is changed. As
      this is the final flight of messages sent from the client the attacker
      knows what the complete hanshake hash value will be that the client will
      send - and therefore knows what the final byte will be. Through a process
      of trial and error the attacker can re-encode the certificate until the
      modified handhshake also has a hash with the same final byte. This means
      that when the Finished message is verified by the server it will be
      correct in all cases.
      
      In practice the MITM would need to be able to perform the same attack
      against both the client and the server. If the attack is only performed
      against the server (say) then the server will not detect the modified
      handshake, but the client will and will abort the connection.
      Fortunately, although OpenSSL is vulnerable to Finished message
      injection, it is not vulnerable if *both* client and server are OpenSSL.
      The reason is that OpenSSL has a hard "floor" for a minimum MTU size
      that it will never go below. This minimum means that a Finished message
      will never be sent in a fragmented form and therefore the MITM does not
      have one of its pre-requisites. Therefore this could only be exploited
      if using OpenSSL and some other DTLS peer that had its own and separate
      Finished message injection flaw.
      
      The fix is to ensure buffered messages are cleared on epoch change.
      Reviewed-by: NRichard Levitte <levitte@openssl.org>
      5cb4d646
    • M
      Fix DTLS buffered message DoS attack · f5c7f5df
      Matt Caswell 提交于
      DTLS can handle out of order record delivery. Additionally since
      handshake messages can be bigger than will fit into a single packet, the
      messages can be fragmented across multiple records (as with normal TLS).
      That means that the messages can arrive mixed up, and we have to
      reassemble them. We keep a queue of buffered messages that are "from the
      future", i.e. messages we're not ready to deal with yet but have arrived
      early. The messages held there may not be full yet - they could be one
      or more fragments that are still in the process of being reassembled.
      
      The code assumes that we will eventually complete the reassembly and
      when that occurs the complete message is removed from the queue at the
      point that we need to use it.
      
      However, DTLS is also tolerant of packet loss. To get around that DTLS
      messages can be retransmitted. If we receive a full (non-fragmented)
      message from the peer after previously having received a fragment of
      that message, then we ignore the message in the queue and just use the
      non-fragmented version. At that point the queued message will never get
      removed.
      
      Additionally the peer could send "future" messages that we never get to
      in order to complete the handshake. Each message has a sequence number
      (starting from 0). We will accept a message fragment for the current
      message sequence number, or for any sequence up to 10 into the future.
      However if the Finished message has a sequence number of 2, anything
      greater than that in the queue is just left there.
      
      So, in those two ways we can end up with "orphaned" data in the queue
      that will never get removed - except when the connection is closed. At
      that point all the queues are flushed.
      
      An attacker could seek to exploit this by filling up the queues with
      lots of large messages that are never going to be used in order to
      attempt a DoS by memory exhaustion.
      
      I will assume that we are only concerned with servers here. It does not
      seem reasonable to be concerned about a memory exhaustion attack on a
      client. They are unlikely to process enough connections for this to be
      an issue.
      
      A "long" handshake with many messages might be 5 messages long (in the
      incoming direction), e.g. ClientHello, Certificate, ClientKeyExchange,
      CertificateVerify, Finished. So this would be message sequence numbers 0
      to 4. Additionally we can buffer up to 10 messages in the future.
      Therefore the maximum number of messages that an attacker could send
      that could get orphaned would typically be 15.
      
      The maximum size that a DTLS message is allowed to be is defined by
      max_cert_list, which by default is 100k. Therefore the maximum amount of
      "orphaned" memory per connection is 1500k.
      
      Message sequence numbers get reset after the Finished message, so
      renegotiation will not extend the maximum number of messages that can be
      orphaned per connection.
      
      As noted above, the queues do get cleared when the connection is closed.
      Therefore in order to mount an effective attack, an attacker would have
      to open many simultaneous connections.
      
      Issue reported by Quan Luo.
      
      CVE-2016-2179
      Reviewed-by: NRichard Levitte <levitte@openssl.org>
      f5c7f5df
    • M
      Fix enable-zlib · 5dfd0381
      Matt Caswell 提交于
      The enable-zlib option was broken by the recent "const" changes.
      Reviewed-by: NStephen Henson <steve@openssl.org>
      5dfd0381
    • R
      VMS: Use strict refdef extern model when building library object files · 68a39960
      Richard Levitte 提交于
      Most of the time, this isn't strictly needed.  However, in the default
      extern model (called relaxed refdef), symbols are treated as weak
      common objects unless they are initialised.  The librarian doesn't
      include weak symbols in the (static) libraries, which renders them
      invisible when linking a program with said those libraries, which is a
      problem at times.
      
      Using the strict refdef model is much more like standard C on all
      other platforms, and thereby avoid the issues that come with the
      relaxed refdef model.
      Reviewed-by: NRich Salz <rsalz@openssl.org>
      68a39960
    • A
      Add test/bio_enc_test.c. · e6ed2b91
      Andy Polyakov 提交于
      RT#4628
      Reviewed-by: NRich Salz <rsalz@openssl.org>
      e6ed2b91
    • A
      evp/bio_enc.c: refine non-overlapping logic. · c1a7dcbe
      Andy Polyakov 提交于
      RT#4628
      Reviewed-by: NRich Salz <rsalz@openssl.org>
      c1a7dcbe
    • A
      ecp_nistz256.c: get is_one on 32-bit platforms right. · 2e929e53
      Andy Polyakov 提交于
      Thanks to Brian Smith for reporting this.
      Reviewed-by: NRich Salz <rsalz@openssl.org>
      2e929e53
    • R
      Move BIO index lock creation · 5a7ad1f0
      Rich Salz 提交于
      Reviewed-by: NRichard Levitte <levitte@openssl.org>
      5a7ad1f0
    • D
      update ordinals · 6b1f413c
      Dr. Stephen Henson 提交于
      Reviewed-by: NViktor Dukhovni <viktor@openssl.org>
      6b1f413c
    • D
      Add X509_getm_notBefore, X509_getm_notAfter · 0b7347ef
      Dr. Stephen Henson 提交于
      Add mutable versions of X509_get0_notBefore and X509_get0_notAfter.
      
      Rename X509_SIG_get0_mutable to X509_SIG_getm.
      Reviewed-by: NViktor Dukhovni <viktor@openssl.org>
      0b7347ef
  2. 21 8月, 2016 2 次提交
  3. 20 8月, 2016 6 次提交
  4. 19 8月, 2016 20 次提交