Previously, there was non-consistent usage of constans SSH_KEX_METHODS,
KEX_METHODS_SIZE and of magic number 10 to reference the arrays used
for algorithm negotiation by peers. This commit settles down to the single
constant and its usage throughout the whole codebase.
Fixes T195
Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Generally, when the extension negotiation is enabled and client supports
SHA2 algorithms for RSA, they are supposed to be prioritized against the
old SHA1. If it is not (ssh-rsa is listed in front of rsa-sha2-* hostkey
algorithms during negotiation), the server wrongly tries to provide the
new typo of signature, ignoring the negotiated algirithm
This commit propagates the digest algorithm from negotiation to the actual
signature functions, which were previously responsible for decision
about the hash algorithm based just on the negotiated extensions.
Fixes T191
Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Send only allowed algorithms in server-sig-algs extension if in FIPS
mode.
Signed-off-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
When in FIPS mode, filter the algorithms to enable only the allowed
ones. If any algorithm is explicitly set through options or
configuration file, they are kept.
Signed-off-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Previously, when no methods were set, the server would enable all
supported methods. This changes this behaviour by setting only the
default methods.
The server in pkd_daemon.c was changed to set explicitly all the
supported methods to keep the previous behaviour.
Signed-off-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
The added option SSH_BIND_OPTIONS_HOSTKEY_ALGORITHMS allows restricting
the signature algorithms to offer to the client for host authentication.
The list set is used as a filter of allowed algorithms.
First a list of possible signature algorithms to offer is created from
the keys set and then such list is filtered against the allowed
algorithms.
Signed-off-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
The added option SSH_BIND_OPTIONS_PUBKEY_ACCEPTED_KEY_TYPES allows
restricting the allowed public key types accepted by the server for
authentication.
Signed-off-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
Fix libssh server sending SSH_MSG_EXT_INFO messages upon rekey: clients
do not expect that message during rekey, and OpenSSH in particular will
log error messages along the lines of:
"kex protocol error: type 7 seq 15"
when the message is received during a rekey.
To fix, check against the session connected flag, which only transitions
to non-zero following the first successful authentication.
bf2c7128ab adds logic to resolve this
issue, but it turns out that checking the session_state to avoid
sending the message is insufficient, because that state is re-set
to SSH_SESSION_STATE_KEXINIT_RECEIVED during rekey.
The before-and-after effects of this change can be observed using the
pkd --rekey flag as so:
./pkd_hello -t torture_pkd_openssh_rsa_rsa_sha2_256 \
-i1 --rekey=16 -v -v -v 2>&1 |
grep -e 'KEY' -e 'EXT'
^ where before the change, multiple SSH_MSG_EXT_INFO send messages are
logged; after, there is only a single SSH_MSG_EXT_INFO logged once upon
the first initial key exchange.
Cross-reference: https://bugs.libssh.org/T121.
Signed-off-by: Jon Simons <jon@jonsimons.org>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Fix a bug with server-side rekeying where the session state at hand
has been toggled to SSH_SESSION_STATE_AUTHENTICATED before performing
the packet send of the SSH2_MSG_USERAUTH_SUCCESS message.
Before this change, what can happen is that during the packet send,
the SSH2_MSG_USERAUTH_SUCCESS message can end up being queued due
to a small rekey data limit value. libssh server will then proceed
to attempt to send KEX-related rekeying messages to the client before
the client has received USERAUTH_SUCCESS. OpenSSH clients do not
expect to undergo rekeying before having been authenticated, and so
will exit with error when this happens.
The behavior before and after can be observed with the pkd test making
use of its new --rekey flag:
./pkd_hello -t torture_pkd_openssh_rsa_rsa_default -i1 --rekey=16 -v -v -v
A new CMake test entry is added for the above variation and can be run
with:
ARGS="-R pkd_hello_rekey" make test
Before the fix, the test will fail; after, the test succeeds while
performing rekeying once every 16 bytes.
Signed-off-by: Jon Simons <jon@jonsimons.org>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
This type is imprecise. We often need the ecdsa_nid in addition to the key type
in order to do anything. We replace this singluar ECDSA type with one type per
curve.
Signed-off-by: Ben Toews <mastahyeti@gmail.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
If the server had an RSA host key, it provided unconditionally SHA2
signatures without consulting the client proposed list of supported host
keys.
This commit implements more fine-grained detection of the extension
to provide the client with valid signatures according to RFC 8332
Section 3.1.
Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
The default rekeying recommendations are specified in
RFC4344 Section 3 (First and Second Rekeying Recommendations).
Additionally, the rekeying can be specified in configuration
file/options allowing us to turn the rekeying off, base it
on time or make it more strict.
The code is highly inspired by the OpenSSH rekeying code.
Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Daiki Ueno <dueno@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
And remove most of the direct access to the structure throughout the code
Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Daiki Ueno <dueno@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
This should not be a problem for well-behaving clients that do not
append the ext-info-c to the rekey, but if they do, we should not
send it either.
Resolves: T121
Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
ssh_send_keepalive() should use global_request() to properly configure
the state machine for packet filtering.
Signed-off-by: Nicolas Viennot <nicolas@viennot.biz>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
The SHA2 variants should be preferred. Also the buffer needs to be
extended to fit all possible public key algorithms.
Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
This includes intercepting the ext-info-c string from
the client kex proposal, configuring the server to allow using
this extension and sending the SSH_MSG_EXT_INFO packet back
to the client after the new keys are in use.
Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
This is a regression introduced by 16217454d5
We import the pubkey into current_crypto which is NULL instead of
next_crypto.
Fixes T90
Signed-off-by: Andreas Schneider <asn@cryptomilk.org>
Summary:
This patch adds support for mbedTLS as a crypto backend for libssh.
mbedTLS is an SSL/TLS library that has been designed to mainly be used
in embedded systems. It is loosely coupled and has a low memory
footprint. mbedTLS also provides a cryptography library (libmbedcrypto)
that can be used without the TLS modules.
The patch is unfortunately quite big, since several new files had to
be added.
DSA is disabled at compile time, since mbedTLS doesn't support DSA
Patch review and feedback would be appreciated, and if any issues or
suggestions appear, I'm willing to work on them.
Signed-off-by: Juraj Vijtiuk <juraj.vijtiuk@sartura.hr>
Test Plan:
* The patch has been tested with a Debug and MinSizeRel build, with
libssh unit tests, client tests and the pkd tests.
* All the tests have been run with valgrind's memcheck, drd and helgrind
tools.
* The examples/samplessh client works when built with the patch.
Reviewers: asn, aris
Subscribers: simonsj
Differential Revision: https://bugs.libssh.org/D1
Expose an API 'ssh_server_init_kex' which allows one to change the set of
key exchange, hostkey, ciphers, MACs, and compression algorithms currently
configured for the ssh_session at hand, after having started the
'ssh_handle_key_exchange' process.
One can use this API from the already-existing 'connect_status_function'
callback to dynamically modify the set of algorithms used after having
received the client banner, but before sending out the initial KEXINIT
message.
For example, one might want to prevent advertising the curve25519 key
exchange algorithm for older OpenSSH clients due to interop bugs.
Fixes T25
Signed-off-by: Jon Simons <jon@jonsimons.org>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Summary:
Based on Dirkjan's original patch series here:
* https://www.libssh.org/archive/libssh/2015-08/0000029.html
Here the changes are adapted for the current master
branch, and expanded to include libgcrypt support.
Co-Authored-By: Dirkjan Bussink <d.bussink@gmail.com>
Signed-off-by: Jon Simons <jon@jonsimons.org>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Test Plan:
* Ran pkd tests for libcrypto and libgcrypt builds.
* Ran client torture_algorithms.c tests for libcrypto and libgcrypt builds.
* Tested across multiple libgcrypts ("1.6.3" and "1.7.6-beta").
Reviewers: aris, asn
Tags: #libssh
Differential Revision: https://bugs.libssh.org/D7
Having "ssh_" prefix in the functions' name will avoid possible clashes
when compiling libssh statically.
Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Having "ssh_" prefix in the functions' name will avoid possible clashes
when compiling libssh statically.
Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Having "ssh_" prefix in the functions' name will avoid possible clashes
when compiling libssh statically.
Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Return SSH_OK for the case that an incoming SSH_MSG_KEXDH_INIT should be
ignored. That is, for the case that the initial 'first_kex_packet_follows'
guess is incorrect. Before this change sessions served with libssh can be
observed to error out unexpectedly early when testing with dropbear clients
that send an incompatible guess.
Signed-off-by: Jon Simons <jon@jonsimons.org>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
The state validation in the packet handlers for SSH_MSG_NEWKEYS and
SSH_MSG_KEXDH_REPLY had a bug which did not raise an error.
The issue has been found and reported by Mariusz Ziule.
Signed-off-by: Aris Adamantiadis <aris@0xbadc0de.be>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
