DTLSv1_listen() is stateless. We never increment the record read sequence
while listening, and we reflect the incoming record's sequence number in our
write sequence.
The logic for doing the write sequence reflection was *after* we had
finished processing the incoming ClientHello and before we write the
ServerHello. In the normal course of events this is fine. However if we
need to write an early alert during ClientHello processing (e.g. no shared
cipher), then we haven't done the write sequence reflection yet. This means
the alert gets written with the wrong sequence number (it will just be set
to whatever value we left it in the last time we wrote something). If the
sequence number is less than expected then the client will believe that the
incoming alert is a retransmit and will therefore drop it, causing the
client to hang waiting for a response from the server.
Fixes#2886
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2915)
Grow TLS/DTLS 16 bytes more than strictly necessary as a precaution against
OOB reads. In most cases this will have no effect because the message buffer
will be large enough already.
Reviewed-by: Matt Caswell <matt@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>
RT4386: Add sanity checks for BN_new()
RT4384: Missing Sanity Checks for RSA_new_method()
RT4384: Missing Sanity Check plus potential NULL pointer deref
RT4382: Missing Sanity Check(s) for BUF_strdup()
RT4380: Missing Sanity Checks for EVP_PKEY_new()
RT4377: Prevent potential NULL pointer dereference
RT4375: Missing sanity checks for OPENSSL_malloc()
RT4374: Potential for NULL pointer dereferences
RT4371: Missing Sanity Check for malloc()
RT4370: Potential for NULL pointer dereferences
Also expand tabs, make update, typo fix (rsalz)
Minor tweak by Paul Dale.
Some minor internal review feedback.
Reviewed-by: Richard Levitte <levitte@openssl.org>
RAND_pseudo_bytes() allows random data to be returned even in low entropy
conditions. Sometimes this is ok. Many times it is not. For the avoidance
of any doubt, replace existing usage of RAND_pseudo_bytes() with
RAND_bytes().
Reviewed-by: Rich Salz <rsalz@openssl.org>
A BIO_flush call in the DTLS code was not correctly setting the |rwstate|
variable to SSL_WRITING. This means that SSL_get_error() will not return
SSL_ERROR_WANT_WRITE in the event of an IO retry.
Reviewed-by: Richard Levitte <levitte@openssl.org>
(cherry picked from commit 67f60be8c9)
If using DTLS and NBIO then if a second or subsequent handshake message
fragment hits a retry, then the retry attempt uses the wrong fragment
offset value. This commit restores the fragment offset from the last
attempt.
Reviewed-by: Richard Levitte <levitte@openssl.org>
(cherry picked from commit 2ad226e88b)
When config'd with "sctp" running "make test" causes a seg fault. This is
actually due to the way ssltest works - it dives under the covers and frees
up BIOs manually and so some BIOs are NULL when the SCTP code does not
expect it. The simplest fix is just to add some sanity checks to make sure
the BIOs aren't NULL before we use them.
This problem occurs in master and 1.0.2. The fix has also been applied to
1.0.1 to keep the code in sync.
Reviewed-by: Tim Hudson <tjh@openssl.org>
(cherry picked from commit f75d5171be)
It should not be possible for DTLS message fragments to span multiple
packets. However previously if the message header fitted exactly into one
packet, and the fragment body was in the next packet then this would work.
Obviously this would fail if packets get re-ordered mid-flight.
Reviewed-by: Tim Hudson <tjh@openssl.org>
dtls1_get_message has an |mt| variable which is the type of the message that
is being requested. If it is negative then any message type is allowed.
However the value of |mt| is not checked in one of the main code paths, so a
peer can send a message of a completely different type and it will be
processed as if it was the message type that we were expecting. This has
very little practical consequences because the current behaviour will still
fail when the format of the message isn't as expected.
Reviewed-by: Andy Polyakov <appro@openssl.org>
(cherry picked from commit 8c2b1d872b)
Commit 9cf0f187 in HEAD, and 68039af3 in 1.0.2, removed a version check
from dtls1_buffer_message() which was needed to distinguish between DTLS
1.x and Cisco's pre-standard version of DTLS (DTLS1_BAD_VER).
Based on an original patch by David Woodhouse <dwmw2@infradead.org>
RT#3703
Reviewed-by: Tim Hudson <tjh@openssl.org>
(cherry picked from commit 5178a16c43)
This should be a one off operation (subsequent invokation of the
script should not move them)
This commit is for the 1.0.2 changes
Reviewed-by: Tim Hudson <tjh@openssl.org>
Sometimes it fails to format them very well, and sometimes it corrupts them!
This commit moves some particularly problematic ones.
Conflicts:
crypto/bn/bn.h
crypto/ec/ec_lcl.h
crypto/rsa/rsa.h
demos/engines/ibmca/hw_ibmca.c
ssl/ssl.h
ssl/ssl3.h
Reviewed-by: Tim Hudson <tjh@openssl.org>
indent will not alter them when reformatting comments
(cherry picked from commit 1d97c84351)
Conflicts:
crypto/bn/bn_lcl.h
crypto/bn/bn_prime.c
crypto/engine/eng_all.c
crypto/rc4/rc4_utl.c
crypto/sha/sha.h
ssl/kssl.c
ssl/t1_lib.c
Reviewed-by: Tim Hudson <tjh@openssl.org>
we will support then dtls1_do_write can go into an infinite loop. This commit
fixes that.
Reviewed-by: Tim Hudson <tjh@openssl.org>
(cherry picked from commit d3d9eef316)
at least the minimum or it will fail.
There were some instances in dtls1_query_mtu where the final mtu can end up
being less than the minimum, i.e. where the user has set an mtu manually. This
shouldn't be allowed. Also remove dtls1_guess_mtu that, despite having
logic for guessing an mtu, was actually only ever used to work out the minimum
mtu to use.
Reviewed-by: Tim Hudson <tjh@openssl.org>
(cherry picked from commit 1620a2e49c)
and instead use the value provided by the underlying BIO. Also provide some
new DTLS_CTRLs so that the library user can set the mtu without needing to
know this constant. These new DTLS_CTRLs provide the capability to set the
link level mtu to be used (i.e. including this IP/UDP overhead). The previous
DTLS_CTRLs required the library user to subtract this overhead first.
Reviewed-by: Tim Hudson <tjh@openssl.org>
(cherry picked from commit 59669b6abf)
Conflicts:
ssl/d1_both.c
mtu that we have received is not less than the minimum. If its less it uses the
minimum instead. The second call to query the mtu does not do that, but
instead uses whatever comes back. We have seen an instance in RT#3592 where we
have got an unreasonably small mtu come back. This commit makes both query
checks consistent.
Reviewed-by: Tim Hudson <tjh@openssl.org>
(cherry picked from commit 6abb0d1f8e)
automatically updated, and we should use the one provided instead.
Unfortunately there are a couple of locations where this is not respected.
Reviewed-by: Tim Hudson <tjh@openssl.org>
(cherry picked from commit 001235778a)
RT#3592 provides an instance where the OPENSSL_assert that this commit
replaces can be hit. I was able to recreate this issue by forcing the
underlying BIO to misbehave and come back with very small mtu values. This
happens the second time around the while loop after we have detected that the
MTU has been exceeded following the call to dtls1_write_bytes.
Reviewed-by: Tim Hudson <tjh@openssl.org>
(cherry picked from commit cf75017bfd)
In a couple of functions, a sequence number would be calculated twice.
Additionally, in |dtls1_process_out_of_seq_message|, we know that
|frag_len| <= |msg_hdr->msg_len| so the later tests for |frag_len <
msg_hdr->msg_len| can be more clearly written as |frag_len !=
msg_hdr->msg_len|, since that's the only remaining case.
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Emilia Käsper <emilia@openssl.org>
Previously, a truncated DTLS fragment in
|dtls1_process_out_of_seq_message| would cause *ok to be cleared, but
the return value would still be the number of bytes read. This would
cause |dtls1_get_message| not to consider it an error and it would
continue processing as normal until the calling function noticed that
*ok was zero.
I can't see an exploit here because |dtls1_get_message| uses
|s->init_num| as the length, which will always be zero from what I can
see.
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Emilia Käsper <emilia@openssl.org>
The |pqueue_insert| function can fail if one attempts to insert a
duplicate sequence number. When handling a fragment of an out of
sequence message, |dtls1_process_out_of_seq_message| would not call
|dtls1_reassemble_fragment| if the fragment's length was zero. It would
then allocate a fresh fragment and attempt to insert it, but ignore the
return value, leaking the fragment.
This allows an attacker to exhaust the memory of a DTLS peer.
Fixes CVE-2014-3507
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Emilia Käsper <emilia@openssl.org>
In |dtls1_reassemble_fragment|, the value of
|msg_hdr->frag_off+frag_len| was being checked against the maximum
handshake message size, but then |msg_len| bytes were allocated for the
fragment buffer. This means that so long as the fragment was within the
allowed size, the pending handshake message could consume 16MB + 2MB
(for the reassembly bitmap). Approx 10 outstanding handshake messages
are allowed, meaning that an attacker could consume ~180MB per DTLS
connection.
In the non-fragmented path (in |dtls1_process_out_of_seq_message|), no
check was applied.
Fixes CVE-2014-3506
Wholly based on patch by Adam Langley with one minor amendment.
Reviewed-by: Emilia Käsper <emilia@openssl.org>
The |item| variable, in both of these cases, may contain a pointer to a
|pitem| structure within |s->d1->buffered_messages|. It was being freed
in the error case while still being in |buffered_messages|. When the
error later caused the |SSL*| to be destroyed, the item would be double
freed.
Thanks to Wah-Teh Chang for spotting that the fix in 1632ef74 was
inconsistent with the other error paths (but correct).
Fixes CVE-2014-3505
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Emilia Käsper <emilia@openssl.org>
A buffer overrun attack can be triggered by sending invalid DTLS fragments
to an OpenSSL DTLS client or server. This is potentially exploitable to
run arbitrary code on a vulnerable client or server.
Fixed by adding consistency check for DTLS fragments.
Thanks to Jüri Aedla for reporting this issue.
(cherry picked from commit 1632ef7448)
Unnecessary recursion when receiving a DTLS hello request can be used to
crash a DTLS client. Fixed by handling DTLS hello request without recursion.
Thanks to Imre Rad (Search-Lab Ltd.) for discovering this issue.
(cherry picked from commit d3152655d5)
A missing bounds check in the handling of the TLS heartbeat extension
can be used to reveal up to 64k of memory to a connected client or
server.
Thanks for Neel Mehta of Google Security for discovering this bug and to
Adam Langley <agl@chromium.org> and Bodo Moeller <bmoeller@acm.org> for
preparing the fix (CVE-2014-0160)
(cherry picked from commit 96db9023b8)
For DTLS we might need to retransmit messages from the previous session
so keep a copy of write context in DTLS retransmission buffers instead
of replacing it after sending CCS. CVE-2013-6450.
(cherry picked from commit 34628967f1)
Since this is always called from DTLS code it is safe to assume the header
length should be the DTLS value. This avoids the need to check the version
number and should work with any version of DTLS (not just 1.0).
(cherry picked from commit 9cf0f18754)
Revise DTLS code. There was a *lot* of code duplication in the
DTLS code that generates records. This makes it harder to maintain and
sometimes a TLS update is omitted by accident from the DTLS code.
Specifically almost all of the record generation functions have code like
this:
some_pointer = buffer + HANDSHAKE_HEADER_LENGTH;
... Record creation stuff ...
set_handshake_header(ssl, SSL_MT_SOMETHING, message_len);
...
write_handshake_message(ssl);
Where the "Record creation stuff" is identical between SSL/TLS and DTLS or
in some cases has very minor differences.
By adding a few fields to SSL3_ENC to include the header length, some flags
and function pointers for handshake header setting and handshake writing the
code can cope with both cases.
(cherry picked from commit 173e72e64c)
Richard Levitte
Matt Caswell
Dr. Stephen Henson
Rich Salz
Viktor Dukhovni
Tim Hudson
Erik Auerswald
Adam Langley
Sami Farin
Michael Tuexen