From ee4af462b68f28cb632375926c67963c03b9dcb4 Mon Sep 17 00:00:00 2001 From: terrafrost Date: Mon, 7 Dec 2020 08:00:44 -0600 Subject: [PATCH] SSH2: end connection faster for algorithm mismatch --- phpseclib/Net/SSH2.php | 73 +++++++++++++++++++++--------------------- 1 file changed, 37 insertions(+), 36 deletions(-) diff --git a/phpseclib/Net/SSH2.php b/phpseclib/Net/SSH2.php index d3cbc1f4..9f3a82af 100644 --- a/phpseclib/Net/SSH2.php +++ b/phpseclib/Net/SSH2.php @@ -1552,6 +1552,39 @@ class Net_SSH2 user_error('No compatible key exchange algorithms found'); return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED); } + + $server_host_key_algorithm = $this->_array_intersect_first($server_host_key_algorithms, $this->server_host_key_algorithms); + if ($server_host_key_algorithm === false) { + user_error('No compatible server host key algorithms found'); + return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED); + } + + $mac_algorithm_out = $this->_array_intersect_first($c2s_mac_algorithms, $this->mac_algorithms_client_to_server); + if ($mac_algorithm_out === false) { + user_error('No compatible client to server message authentication algorithms found'); + return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED); + } + + $mac_algorithm_in = $this->_array_intersect_first($s2c_mac_algorithms, $this->mac_algorithms_server_to_client); + if ($mac_algorithm_in === false) { + user_error('No compatible server to client message authentication algorithms found'); + return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED); + } + + $compression_algorithm_out = $this->_array_intersect_first($c2s_compression_algorithms, $this->compression_algorithms_client_to_server); + if ($compression_algorithm_out === false) { + user_error('No compatible client to server compression algorithms found'); + return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED); + } + //$this->decompress = $compression_algorithm_out == 'zlib'; + + $compression_algorithm_in = $this->_array_intersect_first($s2c_compression_algorithms, $this->compression_algorithms_client_to_server); + if ($compression_algorithm_in === false) { + user_error('No compatible server to client compression algorithms found'); + return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED); + } + //$this->compress = $compression_algorithm_in == 'zlib'; + if (strpos($kex_algorithm, 'diffie-hellman-group-exchange') === 0) { $dh_group_sizes_packed = pack( 'NNN', @@ -1759,12 +1792,6 @@ class Net_SSH2 $this->session_id = $this->exchange_hash; } - $server_host_key_algorithm = $this->_array_intersect_first($server_host_key_algorithms, $this->server_host_key_algorithms); - if ($server_host_key_algorithm === false) { - user_error('No compatible server host key algorithms found'); - return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED); - } - switch ($server_host_key_algorithm) { case 'ssh-dss': $expected_key_format = 'ssh-dss'; @@ -1884,14 +1911,8 @@ class Net_SSH2 $this->decrypt->decrypt(str_repeat("\0", 1536)); } - $mac_algorithm = $this->_array_intersect_first($c2s_mac_algorithms, $this->mac_algorithms_client_to_server); - if ($mac_algorithm === false) { - user_error('No compatible client to server message authentication algorithms found'); - return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED); - } - $createKeyLength = 0; // ie. $mac_algorithm == 'none' - switch ($mac_algorithm) { + switch ($mac_algorithm_out) { case 'hmac-sha2-256': $this->hmac_create = new Crypt_Hash('sha256'); $createKeyLength = 32; @@ -1912,17 +1933,11 @@ class Net_SSH2 $this->hmac_create = new Crypt_Hash('md5-96'); $createKeyLength = 16; } - $this->hmac_create->name = $mac_algorithm; - - $mac_algorithm = $this->_array_intersect_first($s2c_mac_algorithms, $this->mac_algorithms_server_to_client); - if ($mac_algorithm === false) { - user_error('No compatible server to client message authentication algorithms found'); - return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED); - } + $this->hmac_create->name = $mac_algorithm_out; $checkKeyLength = 0; $this->hmac_size = 0; - switch ($mac_algorithm) { + switch ($mac_algorithm_in) { case 'hmac-sha2-256': $this->hmac_check = new Crypt_Hash('sha256'); $checkKeyLength = 32; @@ -1948,7 +1963,7 @@ class Net_SSH2 $checkKeyLength = 16; $this->hmac_size = 12; } - $this->hmac_check->name = $mac_algorithm; + $this->hmac_check->name = $mac_algorithm_in; $key = $kexHash->hash($keyBytes . $this->exchange_hash . 'E' . $this->session_id); while ($createKeyLength > strlen($key)) { @@ -1962,20 +1977,6 @@ class Net_SSH2 } $this->hmac_check->setKey(substr($key, 0, $checkKeyLength)); - $compression_algorithm = $this->_array_intersect_first($c2s_compression_algorithms, $this->compression_algorithms_client_to_server); - if ($compression_algorithm === false) { - user_error('No compatible client to server compression algorithms found'); - return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED); - } - //$this->decompress = $compression_algorithm == 'zlib'; - - $compression_algorithm = $this->_array_intersect_first($s2c_compression_algorithms, $this->compression_algorithms_client_to_server); - if ($compression_algorithm === false) { - user_error('No compatible server to client compression algorithms found'); - return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED); - } - //$this->compress = $compression_algorithm == 'zlib'; - return true; }