Matt Caswell [Fri, 23 Sep 2016 15:58:11 +0000 (16:58 +0100)]
Fix Use After Free for large message sizes
The buffer to receive messages is initialised to 16k. If a message is
received that is larger than that then the buffer is "realloc'd". This can
cause the location of the underlying buffer to change. Anything that is
referring to the old location will be referring to free'd data. In the
recent commit c1ef7c97 (master) and 4b390b6c (1.1.0) the point in the code
where the message buffer is grown was changed. However s->init_msg was not
updated to point at the new location.
Matt Caswell [Wed, 21 Sep 2016 10:20:18 +0000 (11:20 +0100)]
Add warning about a potential pitfall with WPACKET_allocate_bytes()
If the underlying BUF_MEM gets realloc'd then the pointer returned could
become invalid. Therefore we should always ensure that the allocated
memory is filled in prior to any more WPACKET_* calls.
Russian GOST ciphersuites are vulnerable to the KCI attack because they use
long-term keys to establish the connection when ssl client authorization is
on. This change brings the GOST implementation into line with the latest
specs in order to avoid the attack. It should not break backwards
compatibility.
Reviewed-by: Rich Salz <rsalz@openssl.org> Reviewed-by: Matt Caswell <matt@openssl.org>
Matt Caswell [Sat, 10 Sep 2016 20:24:40 +0000 (21:24 +0100)]
Fix a hang with SSL_peek()
If while calling SSL_peek() we read an empty record then we go into an
infinite loop, continually trying to read data from the empty record and
never making any progress. This could be exploited by a malicious peer in
a Denial Of Service attack.
Matt Caswell [Fri, 9 Sep 2016 09:53:39 +0000 (10:53 +0100)]
Fix a mem leak in NPN handling
If a server sent multiple NPN extensions in a single ClientHello then a
mem leak can occur. This will only happen where the client has requested
NPN in the first place. It does not occur during renegotiation. Therefore
the maximum that could be leaked in a single connection with a malicious
server is 64k (the maximum size of the ServerHello extensions section). As
this is client side, only occurs if NPN has been requested and does not
occur during renegotiation this is unlikely to be exploitable.
Matt Caswell [Fri, 9 Sep 2016 09:08:45 +0000 (10:08 +0100)]
Fix OCSP Status Request extension unbounded memory growth
A malicious client can send an excessively large OCSP Status Request
extension. If that client continually requests renegotiation,
sending a large OCSP Status Request extension each time, then there will
be unbounded memory growth on the server. This will eventually lead to a
Denial Of Service attack through memory exhaustion. Servers with a
default configuration are vulnerable even if they do not support OCSP.
Builds using the "no-ocsp" build time option are not affected.
I have also checked other extensions to see if they suffer from a similar
problem but I could not find any other issues.
Matt Caswell [Mon, 19 Sep 2016 10:57:07 +0000 (11:57 +0100)]
Excessive allocation of memory in dtls1_preprocess_fragment()
This issue is very similar to CVE-2016-6307 described in the previous
commit. The underlying defect is different but the security analysis and
impacts are the same except that it impacts DTLS.
A DTLS message includes 3 bytes for its length in the header for the
message.
This would allow for messages up to 16Mb in length. Messages of this length
are excessive and OpenSSL includes a check to ensure that a peer is sending
reasonably sized messages in order to avoid too much memory being consumed
to service a connection. A flaw in the logic of version 1.1.0 means that
memory for the message is allocated too early, prior to the excessive
message length check. Due to way memory is allocated in OpenSSL this could
mean an attacker could force up to 21Mb to be allocated to service a
connection. This could lead to a Denial of Service through memory
exhaustion. However, the excessive message length check still takes place,
and this would cause the connection to immediately fail. Assuming that the
application calls SSL_free() on the failed conneciton in a timely manner
then the 21Mb of allocated memory will then be immediately freed again.
Therefore the excessive memory allocation will be transitory in nature.
This then means that there is only a security impact if:
1) The application does not call SSL_free() in a timely manner in the
event that the connection fails
or
2) The application is working in a constrained environment where there
is very little free memory
or
3) The attacker initiates multiple connection attempts such that there
are multiple connections in a state where memory has been allocated for
the connection; SSL_free() has not yet been called; and there is
insufficient memory to service the multiple requests.
Except in the instance of (1) above any Denial Of Service is likely to
be transitory because as soon as the connection fails the memory is
subsequently freed again in the SSL_free() call. However there is an
increased risk during this period of application crashes due to the lack
of memory - which would then mean a more serious Denial of Service.
This issue does not affect TLS users.
Issue was reported by Shi Lei (Gear Team, Qihoo 360 Inc.).
CVE-2016-6308
Reviewed-by: Richard Levitte <levitte@openssl.org>
Matt Caswell [Mon, 19 Sep 2016 10:39:21 +0000 (11:39 +0100)]
Excessive allocation of memory in tls_get_message_header()
A TLS message includes 3 bytes for its length in the header for the message.
This would allow for messages up to 16Mb in length. Messages of this length
are excessive and OpenSSL includes a check to ensure that a peer is sending
reasonably sized messages in order to avoid too much memory being consumed
to service a connection. A flaw in the logic of version 1.1.0 means that
memory for the message is allocated too early, prior to the excessive
message length check. Due to way memory is allocated in OpenSSL this could
mean an attacker could force up to 21Mb to be allocated to service a
connection. This could lead to a Denial of Service through memory
exhaustion. However, the excessive message length check still takes place,
and this would cause the connection to immediately fail. Assuming that the
application calls SSL_free() on the failed conneciton in a timely manner
then the 21Mb of allocated memory will then be immediately freed again.
Therefore the excessive memory allocation will be transitory in nature.
This then means that there is only a security impact if:
1) The application does not call SSL_free() in a timely manner in the
event that the connection fails
or
2) The application is working in a constrained environment where there
is very little free memory
or
3) The attacker initiates multiple connection attempts such that there
are multiple connections in a state where memory has been allocated for
the connection; SSL_free() has not yet been called; and there is
insufficient memory to service the multiple requests.
Except in the instance of (1) above any Denial Of Service is likely to
be transitory because as soon as the connection fails the memory is
subsequently freed again in the SSL_free() call. However there is an
increased risk during this period of application crashes due to the lack
of memory - which would then mean a more serious Denial of Service.
This issue does not affect DTLS users.
Issue was reported by Shi Lei (Gear Team, Qihoo 360 Inc.).
CVE-2016-6307
Reviewed-by: Richard Levitte <levitte@openssl.org>
Matt Caswell [Wed, 21 Sep 2016 13:07:31 +0000 (14:07 +0100)]
Don't allow too many consecutive warning alerts
Certain warning alerts are ignored if they are received. This can mean that
no progress will be made if one peer continually sends those warning alerts.
Implement a count so that we abort the connection if we receive too many.
Richard Levitte [Wed, 21 Sep 2016 12:44:42 +0000 (14:44 +0200)]
test/x509aux.c: Fix argv loop
There are cases when argc is more trustable than proper argv termination.
Since we trust argc in all other test programs, we might as well treat it
the same way in this program.
Matt Caswell [Tue, 20 Sep 2016 13:47:44 +0000 (14:47 +0100)]
Convert WPACKET_put_bytes to use convenience macros
All the other functions that take an argument for the number of bytes
use convenience macros for this purpose. We should do the same with
WPACKET_put_bytes().
Matt Caswell [Thu, 8 Sep 2016 10:06:29 +0000 (11:06 +0100)]
Convert num_alloc to a size_t in stack.c and tweak style
We were casting num_alloc to size_t in lots of places, or just using it in
a context where size_t makes more sense - so convert it. This simplifies
the code a bit.
Also tweak the style in stack.c a bit following on from the previous
commit
Richard Levitte [Sat, 17 Sep 2016 19:57:29 +0000 (21:57 +0200)]
Have the configuration options 'no-err' and 'no-async' work again
In an earlier attempt to simplify the processing of disabled options,
'no-err' and 'no-async' stopped working properly. 'err' and 'async'
are directories under 'crypto/', but they are special insofar that
they can't be simply skipped, like all the algorithm directories can,
so they need special treatment among the disablable things.
There were some unexpected side effects to this commit, e.g. in SSLv3 a
warning alert gets sent "no_certificate" if a client does not send a
Certificate during Client Auth. With the above commit this causes the
connection to abort, which is incorrect. There may be some other edge cases
like this so we need to have a rethink on this.
Matt Caswell [Thu, 8 Sep 2016 13:32:27 +0000 (14:32 +0100)]
Add some sanity checks around usage of t_fromb64()
The internal SRP function t_fromb64() converts from base64 to binary. It
does not validate that the size of the destination is sufficiently large -
that is up to the callers. In some places there was such a check, but not
in others.
Add an argument to t_fromb64() to provide the size of the destination
buffer and validate that we don't write too much data. Also add some sanity
checks to the callers where appropriate.
With thanks to Shi Lei for reporting this issue.
Reviewed-by: Richard Levitte <levitte@openssl.org>
Viktor Szakats [Tue, 30 Aug 2016 16:56:49 +0000 (18:56 +0200)]
bio.h: fix number of arguments passed to BIO_ptr_ctrl() Reviewed-by: Matt Caswell <matt@openssl.org> Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1520)
Viktor Szakats [Tue, 30 Aug 2016 01:01:16 +0000 (03:01 +0200)]
s_client: avoid warning on Windows/MS-DOS systems
it appears when using gcc/mingw:
```
apps/s_client.c:815:9: warning: variable 'at_eof' set but not used [-Wunused-but-set-variable]
int at_eof = 0;
^~~~~~
``` Reviewed-by: Matt Caswell <matt@openssl.org> Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1512)
Andy Polyakov [Fri, 9 Sep 2016 21:45:57 +0000 (23:45 +0200)]
Configure: impose ^X on whole build procedure.
Traditionally Configure passed $ENV{PERL} to Makefile. But this
resulted in ambiguilty as Configure script could be executed by
interpreter different from one executing remaining scripts. Since
we separate compile- and run-time interpreters with HASHBANGPERL
variable, there is no reason to segment the build procedure.