There was a block of code at the start that used the Camellia cipher. The
original idea behind this was to fill the buffer with non-zero data so that
oversteps can be detected. However this block failed when using no-camellia.
This has been replaced with a RAND_bytes() call.
I also updated the the CTR test section, since it seems to be using a CBC
cipher instead of a CTR cipher.
Reviewed-by: Andy Polyakov <appro@openssl.org>
Also, re-organize RSA check to use goto err.
Add a test case.
Try all checks, not just stopping at first (via Richard Levitte)
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
The variable 'buffer', allocated by EC_POINT_point2buf(), isn't
free'd on the success path.
Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Declare EC{PK,}PARAMETERS_{new,free} functions in public headers. The
free functions are necessary because EC_GROUP_get_ec{pk,}parameters()
was made public by commit 60b350a3ef ("RT3676: Expose ECgroup i2d
functions").
Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Code was relying on an implicit data-sharing through duplication of
loopargs_t pointer-members made by ASYNC_start_job().
Now share structure address instead of structure content.
Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
The following would fail, or rather, freeze:
openssl genrsa -out rsa2048.pem 2048
openssl req -x509 -key rsa2048.pem -keyform PEM -out cert.pem
In that case, the second command wants to read a certificate request
from stdin, because -x509 wasn't fully flagged as being for creating
something new. This changes makes it fully flagged.
RT#4655
Reviewed-by: Andy Polyakov <appro@openssl.org>
Original strategy for page-walking was adjust stack pointer and then
touch pages in order. This kind of asks for double-fault, because
if touch fails, then signal will be delivered to frame above adjusted
stack pointer. But touching pages prior adjusting stack pointer would
upset valgrind. As compromise let's adjust stack pointer in pages,
touching top of the stack. This still asks for double-fault, but at
least prevents corruption of neighbour stack if allocation is to
overstep the guard page.
Also omit predict-non-taken hints as they reportedly trigger illegal
instructions in some VM setups.
Reviewed-by: Richard Levitte <levitte@openssl.org>
Fix an off by one error in the overflow check added by 07bed46f33
("Check for errors in BN_bn2dec()").
Reviewed-by: Stephen Henson <steve@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
In mempacket_test_read(), we've already fetched the top value of the
stack, so when we shift the stack, we don't care for the value. The
compiler needs to be told, or it will complain harshly when we tell it
to be picky.
Reviewed-by: Matt Caswell <matt@openssl.org>
Originally PKCS#12 subroutines treated password strings as ASCII.
It worked as long as they were pure ASCII, but if there were some
none-ASCII characters result was non-interoperable. But fixing it
poses problem accessing data protected with broken password. In
order to make asscess to old data possible add retry with old-style
password.
Reviewed-by: Richard Levitte <levitte@openssl.org>
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: Richard Levitte <levitte@openssl.org>
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: Richard Levitte <levitte@openssl.org>
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: Rich Salz <rsalz@openssl.org>
Add mutable versions of X509_get0_notBefore and X509_get0_notAfter.
Rename X509_SIG_get0_mutable to X509_SIG_getm.
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
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.
Reviewed-by: Rich Salz <rsalz@openssl.org>
