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