Normally, the length of session_id and secret_hash is the same,
but if we will get into rekeying with a peer that changes preference
of key exchange algorithm, the new secret hash can be larger or
smaller than the previous session_id causing invalid reads or writes.
Resolves https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=35485
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>
Rename and refactor how some variables are held in ssh_crypto_struct.
Refactor allocation of dh exchange public keys.
This is in preparation for switching the code to use openssl native DH
handling and allowed to better reason about the code and the overall API.
Signed-off-by: Simo Sorce <simo@redhat.com>
Reviewed-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
The zeroing MUST use the correct cipher length as keys can be both
longer or shorter than the digest. In one case only some part of the key
may end up being zeroed, in the other memory corruption may happen as
we zero memory we do not own.
Signed-off-by: Simo Sorce <simo@redhat.com>
Reviewed-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
This adds the OpenSSH HMACs that do encrypt then mac. This is a more
secure mode than the original HMAC. Newer AEAD ciphers like chacha20 and
AES-GCM are already encrypt-then-mac, but this also adds it for older
legacy clients that don't support those ciphers yet.
Signed-off-by: Dirkjan Bussink <d.bussink@gmail.com>
Reviewed-by: Jon Simons <jon@jonsimons.org>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
This adds a flag to the type structures to track if we use a
Encrypt-then-MAC cipher instead of Encrypt-and-MAC. EtM is a more secure
hashing mechanism.
Signed-off-by: Dirkjan Bussink <d.bussink@gmail.com>
Reviewed-by: Jon Simons <jon@jonsimons.org>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
This is not supported by OpenSSH and not recommended to be implemented
either.
Signed-off-by: Dirkjan Bussink <d.bussink@gmail.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
The commit also propares the internals throughout the code base
for the inclusion of a new AEAD cipher, because previously, the
source code counted only with chacha20-poly1305 cipher, which
is very specific in many cases.
The SSH_HMAC_AEAD_GCM mac algorithm is not actually used, but the name
needed to be defined so we can match in the algorithms selection per
OpenSSH specification (MACs are ignored in case GCM is select as a cipher [1]).
If the provided OpenSSL does not provide EVP_aes_128_gcm() function,
the AES-GCM ciphers will not be compiled in.
[1] https://cvsweb.openbsd.org/src/usr.bin/ssh/PROTOCOL.chacha20poly1305?annotate=HEAD
Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
This involves mostly creation of host keys proofs but needs
to follow the same procedure as the client authentication
signatures.
At the same time, the SHA2 extension is enabled in the pkd
so we are able to atomicaly provide correct signatures and
pass tests.
Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
With this change there is less code specific to the
chacha20-poly1305 cipher found in src/wrapper.c.
Signed-off-by: Jon Simons <jon@jonsimons.org>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
If you want modelines use my vim plugin:
https://github.com/cryptomilk/git-modeline.vim
git config --add vim.modeline "ts=4 sw=4 et"
Signed-off-by: Andreas Schneider <asn@cryptomilk.org>
With this change, a HAVE_LIBCRYPTO #ifdef is removed from wrapper.c.
Now, the libcrypto-specific logic for EVP_CIPHER_CTX_free is moved
into the ssh_cipher_struct cleanup callback handler for those
ciphers.
Signed-off-by: Jon Simons <jon@jonsimons.org>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Fix a gcrypt build error introduced with
48e7b098f86207f8596651b5ba8242a3b834a868.
The ssh_cipher_struct only contains a `ctx` field on
the libcrypto builds, so it can't be referenced unless
within HAVE_LIBCRYPTO.
This build fix preserves the original spirit of the
change in 48e7b098f86207f8596651b5ba8242a3b834a868:
only call `EVP_CIPHER_CTX_free` when `cipher->ctx`
is non-NULL.
Signed-off-by: Jon Simons <jon@jonsimons.org>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
This has been made opaque and it needs to be a pointer.
This is for OpenSSL 1.1.0 support.
Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
* include/libssh/crypto.h (struct ssh_crypto_struct): Provide a
suitable 'ecdh_privkey'.
* include/libssh/ecdh.h: Also define 'HAVE_ECDH' if we do ECC using
libgcrypt.
(ecdh_build_k): New prototype.
* src/CMakeLists.txt (libssh_SRCS): Add backend-specific files.
* src/ecdh.c: Move backend-specific parts to...
* src/ecdh_crypto.c: ... this file.
* src/ecdh_gcrypt.c: New file.
* src/wrapper.c (crypto_free): Free 'ecdh_privkey'.
Signed-off-by: Justus Winter <justus@g10code.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Ensure to free the z_stream structures as allocated from
the gzip.c initcompress, initdecompress functions.
Signed-off-by: Jon Simons <jon@jonsimons.org>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
The code is careful to reenable compression when rekeying.
Signed-off-by: Nicolas Viennot <nicolas@viennot.biz>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
The original code had a typo (COMP was CRYPT). This fixes the zlib compression
method.
Signed-off-by: Nicolas Viennot <nicolas@viennot.biz>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
