Viktor Dukhovni [Fri, 19 Aug 2016 15:59:47 +0000 (11:59 -0400)]
Add -dane_ee_no_namechecks s_client(1) option
The DANE API supports a DANE_FLAG_NO_DANE_EE_NAMECHECKS option, but
there was no way to exercise/enable it via s_client. This commit
addresses that gap.
Matt Caswell [Tue, 19 Jul 2016 10:34:21 +0000 (11:34 +0100)]
Fix some clang warnings
Clang was complaining about some unused functions. Moving the stack
declaration to the header seems to sort it. Also the certstatus variable
in dtlstest needed to be declared static.
Reviewed-by: Richard Levitte <levitte@openssl.org>
Matt Caswell [Fri, 1 Jul 2016 14:20:33 +0000 (15:20 +0100)]
Fix DTLS replay protection
The DTLS implementation provides some protection against replay attacks
in accordance with RFC6347 section 4.1.2.6.
A sliding "window" of valid record sequence numbers is maintained with
the "right" hand edge of the window set to the highest sequence number we
have received so far. Records that arrive that are off the "left" hand
edge of the window are rejected. Records within the window are checked
against a list of records received so far. If we already received it then
we also reject the new record.
If we have not already received the record, or the sequence number is off
the right hand edge of the window then we verify the MAC of the record.
If MAC verification fails then we discard the record. Otherwise we mark
the record as received. If the sequence number was off the right hand edge
of the window, then we slide the window along so that the right hand edge
is in line with the newly received sequence number.
Records may arrive for future epochs, i.e. a record from after a CCS being
sent, can arrive before the CCS does if the packets get re-ordered. As we
have not yet received the CCS we are not yet in a position to decrypt or
validate the MAC of those records. OpenSSL places those records on an
unprocessed records queue. It additionally updates the window immediately,
even though we have not yet verified the MAC. This will only occur if
currently in a handshake/renegotiation.
This could be exploited by an attacker by sending a record for the next
epoch (which does not have to decrypt or have a valid MAC), with a very
large sequence number. This means the right hand edge of the window is
moved very far to the right, and all subsequent legitimate packets are
dropped causing a denial of service.
A similar effect can be achieved during the initial handshake. In this
case there is no MAC key negotiated yet. Therefore an attacker can send a
message for the current epoch with a very large sequence number. The code
will process the record as normal. If the hanshake message sequence number
(as opposed to the record sequence number that we have been talking about
so far) is in the future then the injected message is bufferred to be
handled later, but the window is still updated. Therefore all subsequent
legitimate handshake records are dropped. This aspect is not considered a
security issue because there are many ways for an attacker to disrupt the
initial handshake and prevent it from completing successfully (e.g.
injection of a handshake message will cause the Finished MAC to fail and
the handshake to be aborted). This issue comes about as a result of trying
to do replay protection, but having no integrity mechanism in place yet.
Does it even make sense to have replay protection in epoch 0? That
issue isn't addressed here though.
This addressed an OCAP Audit issue.
CVE-2016-2181
Reviewed-by: Richard Levitte <levitte@openssl.org>
Matt Caswell [Tue, 5 Jul 2016 08:50:55 +0000 (09:50 +0100)]
Add DTLS replay protection test
Injects a record from epoch 1 during epoch 0 handshake, with a record
sequence number in the future, to test that the record replay protection
feature works as expected. This is described more fully in the next commit.
Reviewed-by: Richard Levitte <levitte@openssl.org>
Matt Caswell [Tue, 5 Jul 2016 08:51:08 +0000 (09:51 +0100)]
Fix DTLS unprocessed records bug
During a DTLS handshake we may get records destined for the next epoch
arrive before we have processed the CCS. In that case we can't decrypt or
verify the record yet, so we buffer it for later use. When we do receive
the CCS we work through the queue of unprocessed records and process them.
Unfortunately the act of processing wipes out any existing packet data
that we were still working through. This includes any records from the new
epoch that were in the same packet as the CCS. We should only process the
buffered records if we've not got any data left.
Reviewed-by: Richard Levitte <levitte@openssl.org>
Matt Caswell [Mon, 4 Jul 2016 13:55:50 +0000 (14:55 +0100)]
Split create_ssl_connection()
Split the create_ssl_connection() helper function into two steps: one to
create the SSL objects, and one to actually create the connection. This
provides the ability to make changes to the SSL object before the
connection is actually made.
Reviewed-by: Richard Levitte <levitte@openssl.org>
Matt Caswell [Mon, 4 Jul 2016 13:53:28 +0000 (14:53 +0100)]
Add a DTLS packet mem BIO
This adds a BIO similar to a normal mem BIO but with datagram awareness.
It also has the capability to inject additional packets at arbitrary
locations into the BIO, for testing purposes.
Reviewed-by: Richard Levitte <levitte@openssl.org>
Richard Levitte [Thu, 18 Aug 2016 11:24:27 +0000 (13:24 +0200)]
Simplify indentation of DECLARE_ and IMPLEMENT_ lines
There's no reason we should enumerate every type of IMPLEMENT_ and
DECLARE_ line (and forget the ones we add a little now and then).
They all start with the same first word, let's just take'm all.
Richard Levitte [Wed, 17 Aug 2016 13:06:23 +0000 (15:06 +0200)]
Don't try to init dasync internally
Since dasync isn't installed, and is only ever used as a dynamic
engine, there's no reason to consider it for initialization when
building static engines.
Matt Caswell [Tue, 16 Aug 2016 12:28:14 +0000 (13:28 +0100)]
Provide compat macros for SSL_CTX_set_ecdh_auto() and SSL_set_ecdh_auto()
These functions are no longer relevant to 1.1.0 (we always have auto ecdh
on) - but no reason to break old code that tries to call it. The macros will
only return a dummy "success" result if the app was trying to enable ecdh.
Disabling can't be done in quite this way any more.
Deprecate the function ASN1_STRING_data() and replace with a new function
ASN1_STRING_get0_data() which returns a constant pointer. Update library
to use new function.
If an oversize BIGNUM is presented to BN_bn2dec() it can cause
BN_div_word() to fail and not reduce the value of 't' resulting
in OOB writes to the bn_data buffer and eventually crashing.
Fix by checking return value of BN_div_word() and checking writes
don't overflow buffer.
Matt Caswell [Mon, 1 Aug 2016 16:15:13 +0000 (17:15 +0100)]
Address feedback on SSLv2 ClientHello processing
Feedback on the previous SSLv2 ClientHello processing fix was that it
breaks layering by reading init_num in the record layer. It also does not
detect if there was a previous non-fatal warning.
This is an alternative approach that directly tracks in the record layer
whether this is the first record.
When handling ECDH check to see if the curve is "custom" (X25519 is
currently the only curve of this type) and instead of setting a curve
NID just allocate a key of appropriate type.