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04f9af7dfc
[dh.c ssh-keyscan.c sshconnect.c] more checks for NULL pointers; from grendel@zeitbombe.org; ok deraadt@
871 lines
25 KiB
C
871 lines
25 KiB
C
/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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* All rights reserved
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* Code to connect to a remote host, and to perform the client side of the
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* login (authentication) dialog.
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*
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* As far as I am concerned, the code I have written for this software
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* can be used freely for any purpose. Any derived versions of this
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* software must be clearly marked as such, and if the derived work is
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* incompatible with the protocol description in the RFC file, it must be
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* called by a name other than "ssh" or "Secure Shell".
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*/
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#include "includes.h"
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RCSID("$OpenBSD: sshconnect.c,v 1.127 2002/06/27 08:49:44 markus Exp $");
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#include <openssl/bn.h>
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#include "ssh.h"
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#include "xmalloc.h"
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#include "rsa.h"
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#include "buffer.h"
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#include "packet.h"
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#include "uidswap.h"
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#include "compat.h"
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#include "key.h"
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#include "sshconnect.h"
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#include "hostfile.h"
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#include "log.h"
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#include "readconf.h"
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#include "atomicio.h"
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#include "misc.h"
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#include "readpass.h"
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char *client_version_string = NULL;
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char *server_version_string = NULL;
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/* import */
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extern Options options;
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extern char *__progname;
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extern uid_t original_real_uid;
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extern uid_t original_effective_uid;
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#ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */
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#define INET6_ADDRSTRLEN 46
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#endif
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static const char *
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sockaddr_ntop(struct sockaddr *sa, socklen_t salen)
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{
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static char addrbuf[NI_MAXHOST];
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if (getnameinfo(sa, salen, addrbuf, sizeof(addrbuf), NULL, 0,
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NI_NUMERICHOST) != 0)
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fatal("sockaddr_ntop: getnameinfo NI_NUMERICHOST failed");
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return addrbuf;
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}
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/*
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* Connect to the given ssh server using a proxy command.
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*/
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static int
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ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
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{
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Buffer command;
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const char *cp;
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char *command_string;
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int pin[2], pout[2];
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pid_t pid;
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char strport[NI_MAXSERV];
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/* Convert the port number into a string. */
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snprintf(strport, sizeof strport, "%hu", port);
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/* Build the final command string in the buffer by making the
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appropriate substitutions to the given proxy command. */
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buffer_init(&command);
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for (cp = proxy_command; *cp; cp++) {
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if (cp[0] == '%' && cp[1] == '%') {
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buffer_append(&command, "%", 1);
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cp++;
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continue;
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}
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if (cp[0] == '%' && cp[1] == 'h') {
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buffer_append(&command, host, strlen(host));
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cp++;
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continue;
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}
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if (cp[0] == '%' && cp[1] == 'p') {
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buffer_append(&command, strport, strlen(strport));
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cp++;
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continue;
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}
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buffer_append(&command, cp, 1);
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}
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buffer_append(&command, "\0", 1);
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/* Get the final command string. */
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command_string = buffer_ptr(&command);
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/* Create pipes for communicating with the proxy. */
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if (pipe(pin) < 0 || pipe(pout) < 0)
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fatal("Could not create pipes to communicate with the proxy: %.100s",
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strerror(errno));
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debug("Executing proxy command: %.500s", command_string);
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/* Fork and execute the proxy command. */
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if ((pid = fork()) == 0) {
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char *argv[10];
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/* Child. Permanently give up superuser privileges. */
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seteuid(original_real_uid);
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setuid(original_real_uid);
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/* Redirect stdin and stdout. */
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close(pin[1]);
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if (pin[0] != 0) {
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if (dup2(pin[0], 0) < 0)
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perror("dup2 stdin");
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close(pin[0]);
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}
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close(pout[0]);
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if (dup2(pout[1], 1) < 0)
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perror("dup2 stdout");
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/* Cannot be 1 because pin allocated two descriptors. */
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close(pout[1]);
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/* Stderr is left as it is so that error messages get
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printed on the user's terminal. */
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argv[0] = _PATH_BSHELL;
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argv[1] = "-c";
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argv[2] = command_string;
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argv[3] = NULL;
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/* Execute the proxy command. Note that we gave up any
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extra privileges above. */
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execv(argv[0], argv);
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perror(argv[0]);
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exit(1);
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}
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/* Parent. */
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if (pid < 0)
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fatal("fork failed: %.100s", strerror(errno));
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/* Close child side of the descriptors. */
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close(pin[0]);
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close(pout[1]);
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/* Free the command name. */
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buffer_free(&command);
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/* Set the connection file descriptors. */
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packet_set_connection(pout[0], pin[1]);
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/* Indicate OK return */
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return 0;
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}
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/*
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* Creates a (possibly privileged) socket for use as the ssh connection.
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*/
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static int
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ssh_create_socket(int privileged, int family)
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{
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int sock, gaierr;
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struct addrinfo hints, *res;
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/*
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* If we are running as root and want to connect to a privileged
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* port, bind our own socket to a privileged port.
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*/
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if (privileged) {
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int p = IPPORT_RESERVED - 1;
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PRIV_START;
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sock = rresvport_af(&p, family);
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PRIV_END;
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if (sock < 0)
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error("rresvport: af=%d %.100s", family, strerror(errno));
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else
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debug("Allocated local port %d.", p);
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return sock;
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}
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sock = socket(family, SOCK_STREAM, 0);
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if (sock < 0)
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error("socket: %.100s", strerror(errno));
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/* Bind the socket to an alternative local IP address */
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if (options.bind_address == NULL)
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return sock;
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memset(&hints, 0, sizeof(hints));
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hints.ai_family = family;
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hints.ai_socktype = SOCK_STREAM;
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hints.ai_flags = AI_PASSIVE;
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gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
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if (gaierr) {
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error("getaddrinfo: %s: %s", options.bind_address,
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gai_strerror(gaierr));
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close(sock);
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return -1;
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}
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if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
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error("bind: %s: %s", options.bind_address, strerror(errno));
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close(sock);
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freeaddrinfo(res);
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return -1;
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}
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freeaddrinfo(res);
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return sock;
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}
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/*
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* Opens a TCP/IP connection to the remote server on the given host.
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* The address of the remote host will be returned in hostaddr.
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* If port is 0, the default port will be used. If needpriv is true,
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* a privileged port will be allocated to make the connection.
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* This requires super-user privileges if needpriv is true.
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* Connection_attempts specifies the maximum number of tries (one per
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* second). If proxy_command is non-NULL, it specifies the command (with %h
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* and %p substituted for host and port, respectively) to use to contact
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* the daemon.
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* Return values:
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* 0 for OK
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* ECONNREFUSED if we got a "Connection Refused" by the peer on any address
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* ECONNABORTED if we failed without a "Connection refused"
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* Suitable error messages for the connection failure will already have been
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* printed.
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*/
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int
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ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
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u_short port, int family, int connection_attempts,
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int needpriv, const char *proxy_command)
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{
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int gaierr;
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int on = 1;
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int sock = -1, attempt;
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char ntop[NI_MAXHOST], strport[NI_MAXSERV];
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struct addrinfo hints, *ai, *aitop;
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struct linger linger;
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struct servent *sp;
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/*
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* Did we get only other errors than "Connection refused" (which
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* should block fallback to rsh and similar), or did we get at least
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* one "Connection refused"?
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*/
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int full_failure = 1;
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debug("ssh_connect: needpriv %d", needpriv);
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/* Get default port if port has not been set. */
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if (port == 0) {
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sp = getservbyname(SSH_SERVICE_NAME, "tcp");
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if (sp)
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port = ntohs(sp->s_port);
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else
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port = SSH_DEFAULT_PORT;
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}
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/* If a proxy command is given, connect using it. */
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if (proxy_command != NULL)
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return ssh_proxy_connect(host, port, proxy_command);
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/* No proxy command. */
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memset(&hints, 0, sizeof(hints));
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hints.ai_family = family;
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hints.ai_socktype = SOCK_STREAM;
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snprintf(strport, sizeof strport, "%u", port);
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if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
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fatal("%s: %.100s: %s", __progname, host,
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gai_strerror(gaierr));
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/*
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* Try to connect several times. On some machines, the first time
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* will sometimes fail. In general socket code appears to behave
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* quite magically on many machines.
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*/
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for (attempt = 0; ;) {
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if (attempt > 0)
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debug("Trying again...");
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/* Loop through addresses for this host, and try each one in
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sequence until the connection succeeds. */
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for (ai = aitop; ai; ai = ai->ai_next) {
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if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
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continue;
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if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
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ntop, sizeof(ntop), strport, sizeof(strport),
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NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
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error("ssh_connect: getnameinfo failed");
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continue;
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}
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debug("Connecting to %.200s [%.100s] port %s.",
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host, ntop, strport);
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/* Create a socket for connecting. */
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sock = ssh_create_socket(needpriv, ai->ai_family);
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if (sock < 0)
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/* Any error is already output */
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continue;
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if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
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/* Successful connection. */
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memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
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break;
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} else {
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if (errno == ECONNREFUSED)
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full_failure = 0;
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log("ssh: connect to address %s port %s: %s",
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sockaddr_ntop(ai->ai_addr, ai->ai_addrlen),
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strport, strerror(errno));
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/*
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* Close the failed socket; there appear to
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* be some problems when reusing a socket for
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* which connect() has already returned an
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* error.
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*/
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close(sock);
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}
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}
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if (ai)
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break; /* Successful connection. */
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attempt++;
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if (attempt >= connection_attempts)
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break;
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/* Sleep a moment before retrying. */
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sleep(1);
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}
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freeaddrinfo(aitop);
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/* Return failure if we didn't get a successful connection. */
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if (attempt >= connection_attempts)
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return full_failure ? ECONNABORTED : ECONNREFUSED;
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debug("Connection established.");
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/*
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* Set socket options. We would like the socket to disappear as soon
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* as it has been closed for whatever reason.
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*/
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/* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
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linger.l_onoff = 1;
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linger.l_linger = 5;
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setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
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/* Set keepalives if requested. */
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if (options.keepalives &&
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setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
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sizeof(on)) < 0)
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error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
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/* Set the connection. */
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packet_set_connection(sock, sock);
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return 0;
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}
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/*
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* Waits for the server identification string, and sends our own
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* identification string.
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*/
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static void
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ssh_exchange_identification(void)
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{
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char buf[256], remote_version[256]; /* must be same size! */
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int remote_major, remote_minor, i, mismatch;
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int connection_in = packet_get_connection_in();
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int connection_out = packet_get_connection_out();
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int minor1 = PROTOCOL_MINOR_1;
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/* Read other side\'s version identification. */
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for (;;) {
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for (i = 0; i < sizeof(buf) - 1; i++) {
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int len = atomicio(read, connection_in, &buf[i], 1);
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if (len < 0)
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fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
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if (len != 1)
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fatal("ssh_exchange_identification: Connection closed by remote host");
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if (buf[i] == '\r') {
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buf[i] = '\n';
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buf[i + 1] = 0;
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continue; /**XXX wait for \n */
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}
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if (buf[i] == '\n') {
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buf[i + 1] = 0;
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break;
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}
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}
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buf[sizeof(buf) - 1] = 0;
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if (strncmp(buf, "SSH-", 4) == 0)
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break;
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debug("ssh_exchange_identification: %s", buf);
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}
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server_version_string = xstrdup(buf);
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/*
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* Check that the versions match. In future this might accept
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* several versions and set appropriate flags to handle them.
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*/
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if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
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&remote_major, &remote_minor, remote_version) != 3)
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fatal("Bad remote protocol version identification: '%.100s'", buf);
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debug("Remote protocol version %d.%d, remote software version %.100s",
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remote_major, remote_minor, remote_version);
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compat_datafellows(remote_version);
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mismatch = 0;
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switch (remote_major) {
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case 1:
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if (remote_minor == 99 &&
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(options.protocol & SSH_PROTO_2) &&
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!(options.protocol & SSH_PROTO_1_PREFERRED)) {
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enable_compat20();
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break;
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}
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if (!(options.protocol & SSH_PROTO_1)) {
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mismatch = 1;
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break;
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}
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if (remote_minor < 3) {
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fatal("Remote machine has too old SSH software version.");
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} else if (remote_minor == 3 || remote_minor == 4) {
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/* We speak 1.3, too. */
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enable_compat13();
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minor1 = 3;
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if (options.forward_agent) {
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log("Agent forwarding disabled for protocol 1.3");
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options.forward_agent = 0;
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}
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}
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break;
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case 2:
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if (options.protocol & SSH_PROTO_2) {
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enable_compat20();
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break;
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}
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/* FALLTHROUGH */
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default:
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mismatch = 1;
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break;
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}
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if (mismatch)
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fatal("Protocol major versions differ: %d vs. %d",
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(options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
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remote_major);
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/* Send our own protocol version identification. */
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snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
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compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
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compat20 ? PROTOCOL_MINOR_2 : minor1,
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SSH_VERSION);
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if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
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fatal("write: %.100s", strerror(errno));
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client_version_string = xstrdup(buf);
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chop(client_version_string);
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chop(server_version_string);
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debug("Local version string %.100s", client_version_string);
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}
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/* defaults to 'no' */
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static int
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confirm(const char *prompt)
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{
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const char *msg, *again = "Please type 'yes' or 'no': ";
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char *p;
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int ret = -1;
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if (options.batch_mode)
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return 0;
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for (msg = prompt;;msg = again) {
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p = read_passphrase(msg, RP_ECHO);
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if (p == NULL ||
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(p[0] == '\0') || (p[0] == '\n') ||
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strncasecmp(p, "no", 2) == 0)
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ret = 0;
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if (p && strncasecmp(p, "yes", 3) == 0)
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ret = 1;
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if (p)
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xfree(p);
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if (ret != -1)
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return ret;
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}
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}
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/*
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* check whether the supplied host key is valid, return -1 if the key
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* is not valid. the user_hostfile will not be updated if 'readonly' is true.
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*/
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static int
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check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
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int readonly, const char *user_hostfile, const char *system_hostfile)
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{
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Key *file_key;
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char *type = key_type(host_key);
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char *ip = NULL;
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char hostline[1000], *hostp, *fp;
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HostStatus host_status;
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HostStatus ip_status;
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int local = 0, host_ip_differ = 0;
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int salen;
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char ntop[NI_MAXHOST];
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char msg[1024];
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int len, host_line, ip_line;
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const char *host_file = NULL, *ip_file = NULL;
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/*
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* Force accepting of the host key for loopback/localhost. The
|
|
* problem is that if the home directory is NFS-mounted to multiple
|
|
* machines, localhost will refer to a different machine in each of
|
|
* them, and the user will get bogus HOST_CHANGED warnings. This
|
|
* essentially disables host authentication for localhost; however,
|
|
* this is probably not a real problem.
|
|
*/
|
|
/** hostaddr == 0! */
|
|
switch (hostaddr->sa_family) {
|
|
case AF_INET:
|
|
local = (ntohl(((struct sockaddr_in *)hostaddr)->
|
|
sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
|
|
salen = sizeof(struct sockaddr_in);
|
|
break;
|
|
case AF_INET6:
|
|
local = IN6_IS_ADDR_LOOPBACK(
|
|
&(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
|
|
salen = sizeof(struct sockaddr_in6);
|
|
break;
|
|
default:
|
|
local = 0;
|
|
salen = sizeof(struct sockaddr_storage);
|
|
break;
|
|
}
|
|
if (options.no_host_authentication_for_localhost == 1 && local &&
|
|
options.host_key_alias == NULL) {
|
|
debug("Forcing accepting of host key for "
|
|
"loopback/localhost.");
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* We don't have the remote ip-address for connections
|
|
* using a proxy command
|
|
*/
|
|
if (options.proxy_command == NULL) {
|
|
if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
|
|
NULL, 0, NI_NUMERICHOST) != 0)
|
|
fatal("check_host_key: getnameinfo failed");
|
|
ip = xstrdup(ntop);
|
|
} else {
|
|
ip = xstrdup("<no hostip for proxy command>");
|
|
}
|
|
/*
|
|
* Turn off check_host_ip if the connection is to localhost, via proxy
|
|
* command or if we don't have a hostname to compare with
|
|
*/
|
|
if (options.check_host_ip &&
|
|
(local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
|
|
options.check_host_ip = 0;
|
|
|
|
/*
|
|
* Allow the user to record the key under a different name. This is
|
|
* useful for ssh tunneling over forwarded connections or if you run
|
|
* multiple sshd's on different ports on the same machine.
|
|
*/
|
|
if (options.host_key_alias != NULL) {
|
|
host = options.host_key_alias;
|
|
debug("using hostkeyalias: %s", host);
|
|
}
|
|
|
|
/*
|
|
* Store the host key from the known host file in here so that we can
|
|
* compare it with the key for the IP address.
|
|
*/
|
|
file_key = key_new(host_key->type);
|
|
|
|
/*
|
|
* Check if the host key is present in the user\'s list of known
|
|
* hosts or in the systemwide list.
|
|
*/
|
|
host_file = user_hostfile;
|
|
host_status = check_host_in_hostfile(host_file, host, host_key,
|
|
file_key, &host_line);
|
|
if (host_status == HOST_NEW) {
|
|
host_file = system_hostfile;
|
|
host_status = check_host_in_hostfile(host_file, host, host_key,
|
|
file_key, &host_line);
|
|
}
|
|
/*
|
|
* Also perform check for the ip address, skip the check if we are
|
|
* localhost or the hostname was an ip address to begin with
|
|
*/
|
|
if (options.check_host_ip) {
|
|
Key *ip_key = key_new(host_key->type);
|
|
|
|
ip_file = user_hostfile;
|
|
ip_status = check_host_in_hostfile(ip_file, ip, host_key,
|
|
ip_key, &ip_line);
|
|
if (ip_status == HOST_NEW) {
|
|
ip_file = system_hostfile;
|
|
ip_status = check_host_in_hostfile(ip_file, ip,
|
|
host_key, ip_key, &ip_line);
|
|
}
|
|
if (host_status == HOST_CHANGED &&
|
|
(ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
|
|
host_ip_differ = 1;
|
|
|
|
key_free(ip_key);
|
|
} else
|
|
ip_status = host_status;
|
|
|
|
key_free(file_key);
|
|
|
|
switch (host_status) {
|
|
case HOST_OK:
|
|
/* The host is known and the key matches. */
|
|
debug("Host '%.200s' is known and matches the %s host key.",
|
|
host, type);
|
|
debug("Found key in %s:%d", host_file, host_line);
|
|
if (options.check_host_ip && ip_status == HOST_NEW) {
|
|
if (readonly)
|
|
log("%s host key for IP address "
|
|
"'%.128s' not in list of known hosts.",
|
|
type, ip);
|
|
else if (!add_host_to_hostfile(user_hostfile, ip,
|
|
host_key))
|
|
log("Failed to add the %s host key for IP "
|
|
"address '%.128s' to the list of known "
|
|
"hosts (%.30s).", type, ip, user_hostfile);
|
|
else
|
|
log("Warning: Permanently added the %s host "
|
|
"key for IP address '%.128s' to the list "
|
|
"of known hosts.", type, ip);
|
|
}
|
|
break;
|
|
case HOST_NEW:
|
|
if (readonly)
|
|
goto fail;
|
|
/* The host is new. */
|
|
if (options.strict_host_key_checking == 1) {
|
|
/*
|
|
* User has requested strict host key checking. We
|
|
* will not add the host key automatically. The only
|
|
* alternative left is to abort.
|
|
*/
|
|
error("No %s host key is known for %.200s and you "
|
|
"have requested strict checking.", type, host);
|
|
goto fail;
|
|
} else if (options.strict_host_key_checking == 2) {
|
|
/* The default */
|
|
fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
|
|
snprintf(msg, sizeof(msg),
|
|
"The authenticity of host '%.200s (%s)' can't be "
|
|
"established.\n"
|
|
"%s key fingerprint is %s.\n"
|
|
"Are you sure you want to continue connecting "
|
|
"(yes/no)? ", host, ip, type, fp);
|
|
xfree(fp);
|
|
if (!confirm(msg))
|
|
goto fail;
|
|
}
|
|
if (options.check_host_ip && ip_status == HOST_NEW) {
|
|
snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
|
|
hostp = hostline;
|
|
} else
|
|
hostp = host;
|
|
|
|
/*
|
|
* If not in strict mode, add the key automatically to the
|
|
* local known_hosts file.
|
|
*/
|
|
if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
|
|
log("Failed to add the host to the list of known "
|
|
"hosts (%.500s).", user_hostfile);
|
|
else
|
|
log("Warning: Permanently added '%.200s' (%s) to the "
|
|
"list of known hosts.", hostp, type);
|
|
break;
|
|
case HOST_CHANGED:
|
|
if (options.check_host_ip && host_ip_differ) {
|
|
char *msg;
|
|
if (ip_status == HOST_NEW)
|
|
msg = "is unknown";
|
|
else if (ip_status == HOST_OK)
|
|
msg = "is unchanged";
|
|
else
|
|
msg = "has a different value";
|
|
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
|
|
error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
|
|
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
|
|
error("The %s host key for %s has changed,", type, host);
|
|
error("and the key for the according IP address %s", ip);
|
|
error("%s. This could either mean that", msg);
|
|
error("DNS SPOOFING is happening or the IP address for the host");
|
|
error("and its host key have changed at the same time.");
|
|
if (ip_status != HOST_NEW)
|
|
error("Offending key for IP in %s:%d", ip_file, ip_line);
|
|
}
|
|
/* The host key has changed. */
|
|
fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
|
|
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
|
|
error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
|
|
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
|
|
error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
|
|
error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
|
|
error("It is also possible that the %s host key has just been changed.", type);
|
|
error("The fingerprint for the %s key sent by the remote host is\n%s.",
|
|
type, fp);
|
|
error("Please contact your system administrator.");
|
|
error("Add correct host key in %.100s to get rid of this message.",
|
|
user_hostfile);
|
|
error("Offending key in %s:%d", host_file, host_line);
|
|
xfree(fp);
|
|
|
|
/*
|
|
* If strict host key checking is in use, the user will have
|
|
* to edit the key manually and we can only abort.
|
|
*/
|
|
if (options.strict_host_key_checking) {
|
|
error("%s host key for %.200s has changed and you have "
|
|
"requested strict checking.", type, host);
|
|
goto fail;
|
|
}
|
|
|
|
/*
|
|
* If strict host key checking has not been requested, allow
|
|
* the connection but without password authentication or
|
|
* agent forwarding.
|
|
*/
|
|
if (options.password_authentication) {
|
|
error("Password authentication is disabled to avoid "
|
|
"man-in-the-middle attacks.");
|
|
options.password_authentication = 0;
|
|
}
|
|
if (options.forward_agent) {
|
|
error("Agent forwarding is disabled to avoid "
|
|
"man-in-the-middle attacks.");
|
|
options.forward_agent = 0;
|
|
}
|
|
if (options.forward_x11) {
|
|
error("X11 forwarding is disabled to avoid "
|
|
"man-in-the-middle attacks.");
|
|
options.forward_x11 = 0;
|
|
}
|
|
if (options.num_local_forwards > 0 ||
|
|
options.num_remote_forwards > 0) {
|
|
error("Port forwarding is disabled to avoid "
|
|
"man-in-the-middle attacks.");
|
|
options.num_local_forwards =
|
|
options.num_remote_forwards = 0;
|
|
}
|
|
/*
|
|
* XXX Should permit the user to change to use the new id.
|
|
* This could be done by converting the host key to an
|
|
* identifying sentence, tell that the host identifies itself
|
|
* by that sentence, and ask the user if he/she whishes to
|
|
* accept the authentication.
|
|
*/
|
|
break;
|
|
}
|
|
|
|
if (options.check_host_ip && host_status != HOST_CHANGED &&
|
|
ip_status == HOST_CHANGED) {
|
|
snprintf(msg, sizeof(msg),
|
|
"Warning: the %s host key for '%.200s' "
|
|
"differs from the key for the IP address '%.128s'"
|
|
"\nOffending key for IP in %s:%d",
|
|
type, host, ip, ip_file, ip_line);
|
|
if (host_status == HOST_OK) {
|
|
len = strlen(msg);
|
|
snprintf(msg + len, sizeof(msg) - len,
|
|
"\nMatching host key in %s:%d",
|
|
host_file, host_line);
|
|
}
|
|
if (options.strict_host_key_checking == 1) {
|
|
log(msg);
|
|
error("Exiting, you have requested strict checking.");
|
|
goto fail;
|
|
} else if (options.strict_host_key_checking == 2) {
|
|
strlcat(msg, "\nAre you sure you want "
|
|
"to continue connecting (yes/no)? ", sizeof(msg));
|
|
if (!confirm(msg))
|
|
goto fail;
|
|
} else {
|
|
log(msg);
|
|
}
|
|
}
|
|
|
|
xfree(ip);
|
|
return 0;
|
|
|
|
fail:
|
|
xfree(ip);
|
|
return -1;
|
|
}
|
|
|
|
int
|
|
verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
|
|
{
|
|
struct stat st;
|
|
|
|
/* return ok if the key can be found in an old keyfile */
|
|
if (stat(options.system_hostfile2, &st) == 0 ||
|
|
stat(options.user_hostfile2, &st) == 0) {
|
|
if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
|
|
options.user_hostfile2, options.system_hostfile2) == 0)
|
|
return 0;
|
|
}
|
|
return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
|
|
options.user_hostfile, options.system_hostfile);
|
|
}
|
|
|
|
/*
|
|
* Starts a dialog with the server, and authenticates the current user on the
|
|
* server. This does not need any extra privileges. The basic connection
|
|
* to the server must already have been established before this is called.
|
|
* If login fails, this function prints an error and never returns.
|
|
* This function does not require super-user privileges.
|
|
*/
|
|
void
|
|
ssh_login(Sensitive *sensitive, const char *orighost,
|
|
struct sockaddr *hostaddr, struct passwd *pw)
|
|
{
|
|
char *host, *cp;
|
|
char *server_user, *local_user;
|
|
|
|
local_user = xstrdup(pw->pw_name);
|
|
server_user = options.user ? options.user : local_user;
|
|
|
|
/* Convert the user-supplied hostname into all lowercase. */
|
|
host = xstrdup(orighost);
|
|
for (cp = host; *cp; cp++)
|
|
if (isupper(*cp))
|
|
*cp = tolower(*cp);
|
|
|
|
/* Exchange protocol version identification strings with the server. */
|
|
ssh_exchange_identification();
|
|
|
|
/* Put the connection into non-blocking mode. */
|
|
packet_set_nonblocking();
|
|
|
|
/* key exchange */
|
|
/* authenticate user */
|
|
if (compat20) {
|
|
ssh_kex2(host, hostaddr);
|
|
ssh_userauth2(local_user, server_user, host, sensitive);
|
|
} else {
|
|
ssh_kex(host, hostaddr);
|
|
ssh_userauth1(local_user, server_user, host, sensitive);
|
|
}
|
|
}
|
|
|
|
void
|
|
ssh_put_password(char *password)
|
|
{
|
|
int size;
|
|
char *padded;
|
|
|
|
if (datafellows & SSH_BUG_PASSWORDPAD) {
|
|
packet_put_cstring(password);
|
|
return;
|
|
}
|
|
size = roundup(strlen(password) + 1, 32);
|
|
padded = xmalloc(size);
|
|
memset(padded, 0, size);
|
|
strlcpy(padded, password, size);
|
|
packet_put_string(padded, size);
|
|
memset(padded, 0, size);
|
|
xfree(padded);
|
|
}
|