Mercurial > dropbear
view cli-authpubkey.c @ 1716:6ea18ca8fc03
Delay seedrandom until connections
author | Matt Johnston <matt@ucc.asn.au> |
---|---|
date | Mon, 15 Jun 2020 22:24:34 +0800 |
parents | d18fa38c1fd4 |
children | 8dc43b30c6bf |
line wrap: on
line source
/* * Dropbear SSH * * Copyright (c) 2002,2003 Matt Johnston * Copyright (c) 2004 by Mihnea Stoenescu * All rights reserved. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. */ #include "includes.h" #include "buffer.h" #include "dbutil.h" #include "session.h" #include "ssh.h" #include "runopts.h" #include "auth.h" #include "agentfwd.h" #if DROPBEAR_CLI_PUBKEY_AUTH static void send_msg_userauth_pubkey(sign_key *key, enum signature_type sigtype, int realsign); /* Called when we receive a SSH_MSG_USERAUTH_FAILURE for a pubkey request. * We use it to remove the key we tried from the list */ void cli_pubkeyfail() { m_list_elem *iter; for (iter = cli_opts.privkeys->first; iter; iter = iter->next) { sign_key *iter_key = (sign_key*)iter->item; if (iter_key == cli_ses.lastprivkey) { /* found the failing key */ list_remove(iter); sign_key_free(iter_key); cli_ses.lastprivkey = NULL; return; } } } void recv_msg_userauth_pk_ok() { m_list_elem *iter; buffer* keybuf = NULL; char* algotype = NULL; unsigned int algolen; enum signkey_type keytype; enum signature_type sigtype; unsigned int remotelen; TRACE(("enter recv_msg_userauth_pk_ok")) algotype = buf_getstring(ses.payload, &algolen); sigtype = signature_type_from_name(algotype, algolen); keytype = signkey_type_from_signature(sigtype); TRACE(("recv_msg_userauth_pk_ok: type %d", sigtype)) m_free(algotype); keybuf = buf_new(MAX_PUBKEY_SIZE); remotelen = buf_getint(ses.payload); /* Iterate through our keys, find which one it was that matched, and * send a real request with that key */ for (iter = cli_opts.privkeys->first; iter; iter = iter->next) { sign_key *key = (sign_key*)iter->item; if (key->type != keytype) { /* Types differed */ TRACE(("types differed")) continue; } /* Now we compare the contents of the key */ keybuf->pos = keybuf->len = 0; buf_put_pub_key(keybuf, key, keytype); buf_setpos(keybuf, 0); buf_incrpos(keybuf, 4); /* first int is the length of the remainder (ie remotelen) which has already been taken from the remote buffer */ if (keybuf->len-4 != remotelen) { TRACE(("lengths differed: localh %d remote %d", keybuf->len, remotelen)) /* Lengths differed */ continue; } if (memcmp(buf_getptr(keybuf, remotelen), buf_getptr(ses.payload, remotelen), remotelen) != 0) { /* Data didn't match this key */ TRACE(("data differed")) continue; } /* Success */ break; } buf_free(keybuf); if (iter != NULL) { TRACE(("matching key")) /* XXX TODO: if it's an encrypted key, here we ask for their * password */ send_msg_userauth_pubkey((sign_key*)iter->item, sigtype, 1); } else { TRACE(("That was whacky. We got told that a key was valid, but it didn't match our list. Sounds like dodgy code on Dropbear's part")) } TRACE(("leave recv_msg_userauth_pk_ok")) } static void cli_buf_put_sign(buffer* buf, sign_key *key, enum signature_type sigtype, const buffer *data_buf) { #if DROPBEAR_CLI_AGENTFWD // TODO: rsa-sha256 agent if (key->source == SIGNKEY_SOURCE_AGENT) { /* Format the agent signature ourselves, as buf_put_sign would. */ buffer *sigblob; sigblob = buf_new(MAX_PUBKEY_SIZE); agent_buf_sign(sigblob, key, data_buf, sigtype); buf_putbufstring(buf, sigblob); buf_free(sigblob); } else #endif /* DROPBEAR_CLI_AGENTFWD */ { buf_put_sign(buf, key, sigtype, data_buf); } } static void send_msg_userauth_pubkey(sign_key *key, enum signature_type sigtype, int realsign) { const char *algoname = NULL; unsigned int algolen; buffer* sigbuf = NULL; enum signkey_type keytype = signkey_type_from_signature(sigtype); TRACE(("enter send_msg_userauth_pubkey sigtype %d", sigtype)) CHECKCLEARTOWRITE(); buf_putbyte(ses.writepayload, SSH_MSG_USERAUTH_REQUEST); buf_putstring(ses.writepayload, cli_opts.username, strlen(cli_opts.username)); buf_putstring(ses.writepayload, SSH_SERVICE_CONNECTION, SSH_SERVICE_CONNECTION_LEN); buf_putstring(ses.writepayload, AUTH_METHOD_PUBKEY, AUTH_METHOD_PUBKEY_LEN); buf_putbyte(ses.writepayload, realsign); algoname = signature_name_from_type(sigtype, &algolen); buf_putstring(ses.writepayload, algoname, algolen); buf_put_pub_key(ses.writepayload, key, keytype); if (realsign) { TRACE(("realsign")) /* We put the signature as well - this contains string(session id), then * the contents of the write payload to this point */ sigbuf = buf_new(4 + ses.session_id->len + ses.writepayload->len); buf_putbufstring(sigbuf, ses.session_id); buf_putbytes(sigbuf, ses.writepayload->data, ses.writepayload->len); cli_buf_put_sign(ses.writepayload, key, sigtype, sigbuf); buf_free(sigbuf); /* Nothing confidential in the buffer */ } encrypt_packet(); TRACE(("leave send_msg_userauth_pubkey")) } /* Returns 1 if a key was tried */ int cli_auth_pubkey() { enum signature_type sigtype = DROPBEAR_SIGNATURE_NONE; TRACE(("enter cli_auth_pubkey")) #if DROPBEAR_CLI_AGENTFWD if (!cli_opts.agent_keys_loaded) { /* get the list of available keys from the agent */ cli_load_agent_keys(cli_opts.privkeys); cli_opts.agent_keys_loaded = 1; TRACE(("cli_auth_pubkey: agent keys loaded")) } #endif /* iterate through privkeys to remove ones not allowed in server-sig-algs */ while (cli_opts.privkeys->first) { sign_key * key = (sign_key*)cli_opts.privkeys->first->item; if (cli_ses.server_sig_algs) { #if DROPBEAR_RSA if (key->type == DROPBEAR_SIGNKEY_RSA) { #if DROPBEAR_RSA_SHA256 if (buf_has_algo(cli_ses.server_sig_algs, SSH_SIGNATURE_RSA_SHA256) == DROPBEAR_SUCCESS) { sigtype = DROPBEAR_SIGNATURE_RSA_SHA256; TRACE(("server-sig-algs allows rsa sha256")) break; } #endif /* DROPBEAR_RSA_SHA256 */ #if DROPBEAR_RSA_SHA1 if (buf_has_algo(cli_ses.server_sig_algs, SSH_SIGNKEY_RSA) == DROPBEAR_SUCCESS) { sigtype = DROPBEAR_SIGNATURE_RSA_SHA1; TRACE(("server-sig-algs allows rsa sha1")) break; } #endif /* DROPBEAR_RSA_SHA256 */ } else #endif /* DROPBEAR_RSA */ { /* Not RSA */ const char *name = NULL; sigtype = signature_type_from_signkey(key->type); name = signature_name_from_type(sigtype, NULL); if (buf_has_algo(cli_ses.server_sig_algs, name) == DROPBEAR_SUCCESS) { TRACE(("server-sig-algs allows %s", name)) break; } } /* No match, skip this key */ TRACE(("server-sig-algs no match keytype %d, skipping", key->type)) key = list_remove(cli_opts.privkeys->first); sign_key_free(key); continue; } else { /* Server didn't provide a server-sig-algs list, we'll assume all except rsa-sha256 are OK. */ #if DROPBEAR_RSA if (key->type == DROPBEAR_SIGNKEY_RSA) { #if DROPBEAR_RSA_SHA1 sigtype = DROPBEAR_SIGNATURE_RSA_SHA1; TRACE(("no server-sig-algs, using rsa sha1")) break; #else /* only support rsa-sha256, skip this key */ TRACE(("no server-sig-algs, skipping rsa sha256")) key = list_remove(cli_opts.privkeys->first); sign_key_free(key); continue; #endif } /* key->type == DROPBEAR_SIGNKEY_RSA */ #endif /* DROPBEAR_RSA */ sigtype = signature_type_from_signkey(key->type); TRACE(("no server-sig-algs, using key")) break; } } if (cli_opts.privkeys->first) { sign_key * key = (sign_key*)cli_opts.privkeys->first->item; /* Send a trial request */ send_msg_userauth_pubkey(key, sigtype, 0); cli_ses.lastprivkey = key; TRACE(("leave cli_auth_pubkey-success")) return 1; } else { /* no more keys left */ TRACE(("leave cli_auth_pubkey-failure")) return 0; } } void cli_auth_pubkey_cleanup() { #if DROPBEAR_CLI_AGENTFWD m_close(cli_opts.agent_fd); cli_opts.agent_fd = -1; #endif while (cli_opts.privkeys->first) { sign_key * key = list_remove(cli_opts.privkeys->first); sign_key_free(key); } } #endif /* Pubkey auth */