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1519 lines
46 KiB
C
1519 lines
46 KiB
C
/*
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sshconnect.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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Created: Sat Mar 18 22:15:47 1995 ylo
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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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#include "config.h"
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#include "includes.h"
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RCSID("$Id: sshconnect.c,v 1.4 1999/11/08 05:15:55 damien Exp $");
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#ifdef HAVE_OPENSSL
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#include <openssl/bn.h>
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#include <openssl/md5.h>
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#endif
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#ifdef HAVE_SSL
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#include <ssl/bn.h>
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#include <ssl/md5.h>
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#endif
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#include "xmalloc.h"
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#include "rsa.h"
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#include "ssh.h"
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#include "packet.h"
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#include "authfd.h"
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#include "cipher.h"
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#include "mpaux.h"
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#include "uidswap.h"
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#include "compat.h"
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/* Session id for the current session. */
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unsigned char session_id[16];
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/* Connect to the given ssh server using a proxy command. */
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int
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ssh_proxy_connect(const char *host, int port, uid_t original_real_uid,
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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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int pid;
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char portstring[100];
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/* Convert the port number into a string. */
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snprintf(portstring, sizeof portstring, "%d", port);
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/* Build the final command string in the buffer by making the appropriate
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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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{
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if (cp[0] == '%' && cp[1] == '%')
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{
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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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{
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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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{
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buffer_append(&command, portstring, strlen(portstring));
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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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{
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char *argv[10];
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/* Child. Permanently give up superuser privileges. */
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permanently_set_uid(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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{
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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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close(pout[1]); /* Cannot be 1 because pin allocated two descriptors. */
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/* Stderr is left as it is so that error messages get printed on
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the user's terminal. */
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argv[0] = "/bin/sh";
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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 extra
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privileges above. */
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execv("/bin/sh", argv);
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perror("/bin/sh");
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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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return 1;
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}
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/* Creates a (possibly privileged) socket for use as the ssh connection. */
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int ssh_create_socket(uid_t original_real_uid, int privileged)
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{
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int sock;
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/* If we are running as root and want to connect to a privileged port,
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bind our own socket to a privileged port. */
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if (privileged)
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{
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int p = IPPORT_RESERVED - 1;
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sock = rresvport(&p);
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if (sock < 0)
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fatal("rresvport: %.100s", strerror(errno));
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debug("Allocated local port %d.", p);
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}
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else
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{
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/* Just create an ordinary socket on arbitrary port. We use the
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user's uid to create the socket. */
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temporarily_use_uid(original_real_uid);
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sock = socket(AF_INET, SOCK_STREAM, 0);
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if (sock < 0)
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fatal("socket: %.100s", strerror(errno));
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restore_uid();
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}
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return sock;
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}
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/* Opens a TCP/IP connection to the remote server on the given host. If
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port is 0, the default port will be used. If anonymous is zero,
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a privileged port will be allocated to make the connection.
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This requires super-user privileges if anonymous is false.
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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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int ssh_connect(const char *host, struct sockaddr_in *hostaddr,
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int port, int connection_attempts,
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int anonymous, uid_t original_real_uid,
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const char *proxy_command)
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{
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int sock = -1, attempt, i;
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int on = 1;
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struct servent *sp;
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struct hostent *hp;
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struct linger linger;
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debug("ssh_connect: getuid %d geteuid %d anon %d",
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(int)getuid(), (int)geteuid(), anonymous);
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/* Get default port if port has not been set. */
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if (port == 0)
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{
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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, original_real_uid, proxy_command);
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/* No proxy command. */
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/* No host lookup made yet. */
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hp = NULL;
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/* Try to connect several times. On some machines, the first time will
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sometimes fail. In general socket code appears to behave quite
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magically on many machines. */
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for (attempt = 0; attempt < connection_attempts; attempt++)
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{
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if (attempt > 0)
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debug("Trying again...");
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/* Try to parse the host name as a numeric inet address. */
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memset(hostaddr, 0, sizeof(hostaddr));
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hostaddr->sin_family = AF_INET;
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hostaddr->sin_port = htons(port);
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hostaddr->sin_addr.s_addr = inet_addr(host);
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if ((hostaddr->sin_addr.s_addr & 0xffffffff) != 0xffffffff)
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{
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/* Valid numeric IP address */
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debug("Connecting to %.100s port %d.",
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inet_ntoa(hostaddr->sin_addr), port);
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/* Create a socket. */
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sock = ssh_create_socket(original_real_uid,
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!anonymous && geteuid() == 0 &&
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port < IPPORT_RESERVED);
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/* Connect to the host. We use the user's uid in the hope that
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it will help with the problems of tcp_wrappers showing the
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remote uid as root. */
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temporarily_use_uid(original_real_uid);
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if (connect(sock, (struct sockaddr *)hostaddr, sizeof(*hostaddr))
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>= 0)
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{
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/* Successful connect. */
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restore_uid();
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break;
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}
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debug("connect: %.100s", strerror(errno));
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restore_uid();
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/* Destroy the failed socket. */
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shutdown(sock, SHUT_RDWR);
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close(sock);
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}
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else
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{
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/* Not a valid numeric inet address. */
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/* Map host name to an address. */
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if (!hp)
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hp = gethostbyname(host);
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if (!hp)
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fatal("Bad host name: %.100s", host);
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if (!hp->h_addr_list[0])
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fatal("Host does not have an IP address: %.100s", host);
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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 (i = 0; hp->h_addr_list[i]; i++)
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{
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/* Set the address to connect to. */
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hostaddr->sin_family = hp->h_addrtype;
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memcpy(&hostaddr->sin_addr, hp->h_addr_list[i],
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sizeof(hostaddr->sin_addr));
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debug("Connecting to %.200s [%.100s] port %d.",
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host, inet_ntoa(hostaddr->sin_addr), port);
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/* Create a socket for connecting. */
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sock = ssh_create_socket(original_real_uid,
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!anonymous && geteuid() == 0 &&
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port < IPPORT_RESERVED);
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/* Connect to the host. We use the user's uid in the hope that
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it will help with tcp_wrappers showing the remote uid as
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root. */
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temporarily_use_uid(original_real_uid);
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if (connect(sock, (struct sockaddr *)hostaddr,
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sizeof(*hostaddr)) >= 0)
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{
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/* Successful connection. */
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restore_uid();
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break;
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}
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debug("connect: %.100s", strerror(errno));
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restore_uid();
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/* Close the failed socket; there appear to be some problems
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when reusing a socket for which connect() has already
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returned an error. */
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shutdown(sock, SHUT_RDWR);
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close(sock);
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}
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if (hp->h_addr_list[i])
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break; /* Successful connection. */
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}
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/* Sleep a moment before retrying. */
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sleep(1);
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}
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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 0;
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debug("Connection established.");
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/* Set socket options. We would like the socket to disappear as soon as
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it has been closed for whatever reason. */
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/* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
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setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (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 the connection. */
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packet_set_connection(sock, sock);
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return 1;
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}
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/* Checks if the user has an authentication agent, and if so, tries to
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authenticate using the agent. */
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int
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try_agent_authentication()
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{
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int status, type, bits;
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char *comment;
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AuthenticationConnection *auth;
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unsigned char response[16];
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unsigned int i;
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BIGNUM *e, *n, *challenge;
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/* Get connection to the agent. */
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auth = ssh_get_authentication_connection();
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if (!auth)
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return 0;
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e = BN_new();
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n = BN_new();
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challenge = BN_new();
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/* Loop through identities served by the agent. */
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for (status = ssh_get_first_identity(auth, &bits, e, n, &comment);
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status;
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status = ssh_get_next_identity(auth, &bits, e, n, &comment))
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{
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int plen, clen;
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/* Try this identity. */
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debug("Trying RSA authentication via agent with '%.100s'", comment);
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xfree(comment);
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/* Tell the server that we are willing to authenticate using this key. */
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packet_start(SSH_CMSG_AUTH_RSA);
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packet_put_bignum(n);
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packet_send();
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packet_write_wait();
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/* Wait for server's response. */
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type = packet_read(&plen);
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/* The server sends failure if it doesn\'t like our key or does not
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support RSA authentication. */
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if (type == SSH_SMSG_FAILURE)
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{
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debug("Server refused our key.");
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continue;
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}
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/* Otherwise it should have sent a challenge. */
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if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
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packet_disconnect("Protocol error during RSA authentication: %d",
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type);
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packet_get_bignum(challenge, &clen);
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packet_integrity_check(plen, clen, type);
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debug("Received RSA challenge from server.");
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/* Ask the agent to decrypt the challenge. */
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if (!ssh_decrypt_challenge(auth, bits, e, n, challenge,
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session_id, 1, response))
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{
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/* The agent failed to authenticate this identifier although it
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advertised it supports this. Just return a wrong value. */
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log("Authentication agent failed to decrypt challenge.");
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memset(response, 0, sizeof(response));
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}
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debug("Sending response to RSA challenge.");
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/* Send the decrypted challenge back to the server. */
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packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
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for (i = 0; i < 16; i++)
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packet_put_char(response[i]);
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packet_send();
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packet_write_wait();
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/* Wait for response from the server. */
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type = packet_read(&plen);
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/* The server returns success if it accepted the authentication. */
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if (type == SSH_SMSG_SUCCESS)
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{
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debug("RSA authentication accepted by server.");
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BN_clear_free(e);
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BN_clear_free(n);
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BN_clear_free(challenge);
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return 1;
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}
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/* Otherwise it should return failure. */
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if (type != SSH_SMSG_FAILURE)
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packet_disconnect("Protocol error waiting RSA auth response: %d",
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type);
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}
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BN_clear_free(e);
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BN_clear_free(n);
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BN_clear_free(challenge);
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debug("RSA authentication using agent refused.");
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return 0;
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}
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/* Computes the proper response to a RSA challenge, and sends the response to
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the server. */
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void
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respond_to_rsa_challenge(BIGNUM *challenge, RSA *prv)
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{
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unsigned char buf[32], response[16];
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MD5_CTX md;
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int i, len;
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/* Decrypt the challenge using the private key. */
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rsa_private_decrypt(challenge, challenge, prv);
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/* Compute the response. */
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/* The response is MD5 of decrypted challenge plus session id. */
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len = BN_num_bytes(challenge);
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if (len <= 0 || len > sizeof(buf))
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packet_disconnect("respond_to_rsa_challenge: bad challenge length %d",
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len);
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memset(buf, 0, sizeof(buf));
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BN_bn2bin(challenge, buf + sizeof(buf) - len);
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MD5_Init(&md);
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MD5_Update(&md, buf, 32);
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MD5_Update(&md, session_id, 16);
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MD5_Final(response, &md);
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debug("Sending response to host key RSA challenge.");
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/* Send the response back to the server. */
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packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
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for (i = 0; i < 16; i++)
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packet_put_char(response[i]);
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packet_send();
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packet_write_wait();
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memset(buf, 0, sizeof(buf));
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memset(response, 0, sizeof(response));
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memset(&md, 0, sizeof(md));
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}
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/* Checks if the user has authentication file, and if so, tries to authenticate
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the user using it. */
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int
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try_rsa_authentication(struct passwd *pw, const char *authfile,
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int may_ask_passphrase)
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{
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BIGNUM *challenge;
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RSA *private_key;
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RSA *public_key;
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char *passphrase, *comment;
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int type, i;
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int plen, clen;
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/* Try to load identification for the authentication key. */
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public_key = RSA_new();
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if (!load_public_key(authfile, public_key, &comment)) {
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RSA_free(public_key);
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return 0; /* Could not load it. Fail. */
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}
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debug("Trying RSA authentication with key '%.100s'", comment);
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/* Tell the server that we are willing to authenticate using this key. */
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packet_start(SSH_CMSG_AUTH_RSA);
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packet_put_bignum(public_key->n);
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packet_send();
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packet_write_wait();
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/* We no longer need the public key. */
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RSA_free(public_key);
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/* Wait for server's response. */
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type = packet_read(&plen);
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/* The server responds with failure if it doesn\'t like our key or doesn\'t
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support RSA authentication. */
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if (type == SSH_SMSG_FAILURE)
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{
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debug("Server refused our key.");
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xfree(comment);
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return 0; /* Server refuses to authenticate with this key. */
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}
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/* Otherwise, the server should respond with a challenge. */
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if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
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packet_disconnect("Protocol error during RSA authentication: %d", type);
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/* Get the challenge from the packet. */
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challenge = BN_new();
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packet_get_bignum(challenge, &clen);
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packet_integrity_check(plen, clen, type);
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debug("Received RSA challenge from server.");
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private_key = RSA_new();
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/* Load the private key. Try first with empty passphrase; if it fails,
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ask for a passphrase. */
|
|
if (!load_private_key(authfile, "", private_key, NULL))
|
|
{
|
|
char buf[300];
|
|
/* Request passphrase from the user. We read from /dev/tty to make
|
|
this work even if stdin has been redirected. If running in
|
|
batch mode, we just use the empty passphrase, which will fail and
|
|
return. */
|
|
snprintf(buf, sizeof buf,
|
|
"Enter passphrase for RSA key '%.100s': ", comment);
|
|
if (may_ask_passphrase)
|
|
passphrase = read_passphrase(buf, 0);
|
|
else
|
|
{
|
|
debug("Will not query passphrase for %.100s in batch mode.",
|
|
comment);
|
|
passphrase = xstrdup("");
|
|
}
|
|
|
|
/* Load the authentication file using the pasphrase. */
|
|
if (!load_private_key(authfile, passphrase, private_key, NULL))
|
|
{
|
|
memset(passphrase, 0, strlen(passphrase));
|
|
xfree(passphrase);
|
|
error("Bad passphrase.");
|
|
|
|
/* Send a dummy response packet to avoid protocol error. */
|
|
packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
|
|
for (i = 0; i < 16; i++)
|
|
packet_put_char(0);
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
/* Expect the server to reject it... */
|
|
packet_read_expect(&plen, SSH_SMSG_FAILURE);
|
|
xfree(comment);
|
|
return 0;
|
|
}
|
|
|
|
/* Destroy the passphrase. */
|
|
memset(passphrase, 0, strlen(passphrase));
|
|
xfree(passphrase);
|
|
}
|
|
|
|
/* We no longer need the comment. */
|
|
xfree(comment);
|
|
|
|
/* Compute and send a response to the challenge. */
|
|
respond_to_rsa_challenge(challenge, private_key);
|
|
|
|
/* Destroy the private key. */
|
|
RSA_free(private_key);
|
|
|
|
/* We no longer need the challenge. */
|
|
BN_clear_free(challenge);
|
|
|
|
/* Wait for response from the server. */
|
|
type = packet_read(&plen);
|
|
if (type == SSH_SMSG_SUCCESS)
|
|
{
|
|
debug("RSA authentication accepted by server.");
|
|
return 1;
|
|
}
|
|
if (type != SSH_SMSG_FAILURE)
|
|
packet_disconnect("Protocol error waiting RSA auth response: %d", type);
|
|
debug("RSA authentication refused.");
|
|
return 0;
|
|
}
|
|
|
|
/* Tries to authenticate the user using combined rhosts or /etc/hosts.equiv
|
|
authentication and RSA host authentication. */
|
|
|
|
int
|
|
try_rhosts_rsa_authentication(const char *local_user, RSA *host_key)
|
|
{
|
|
int type;
|
|
BIGNUM *challenge;
|
|
int plen, clen;
|
|
|
|
debug("Trying rhosts or /etc/hosts.equiv with RSA host authentication.");
|
|
|
|
/* Tell the server that we are willing to authenticate using this key. */
|
|
packet_start(SSH_CMSG_AUTH_RHOSTS_RSA);
|
|
packet_put_string(local_user, strlen(local_user));
|
|
packet_put_int(BN_num_bits(host_key->n));
|
|
packet_put_bignum(host_key->e);
|
|
packet_put_bignum(host_key->n);
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
/* Wait for server's response. */
|
|
type = packet_read(&plen);
|
|
|
|
/* The server responds with failure if it doesn't admit our .rhosts
|
|
authentication or doesn't know our host key. */
|
|
if (type == SSH_SMSG_FAILURE)
|
|
{
|
|
debug("Server refused our rhosts authentication or host key.");
|
|
return 0; /* Server refuses to authenticate us with this method. */
|
|
}
|
|
|
|
/* Otherwise, the server should respond with a challenge. */
|
|
if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
|
|
packet_disconnect("Protocol error during RSA authentication: %d", type);
|
|
|
|
/* Get the challenge from the packet. */
|
|
challenge = BN_new();
|
|
packet_get_bignum(challenge, &clen);
|
|
|
|
packet_integrity_check(plen, clen, type);
|
|
|
|
debug("Received RSA challenge for host key from server.");
|
|
|
|
/* Compute a response to the challenge. */
|
|
respond_to_rsa_challenge(challenge, host_key);
|
|
|
|
/* We no longer need the challenge. */
|
|
BN_clear_free(challenge);
|
|
|
|
/* Wait for response from the server. */
|
|
type = packet_read(&plen);
|
|
if (type == SSH_SMSG_SUCCESS)
|
|
{
|
|
debug("Rhosts or /etc/hosts.equiv with RSA host authentication accepted by server.");
|
|
return 1;
|
|
}
|
|
if (type != SSH_SMSG_FAILURE)
|
|
packet_disconnect("Protocol error waiting RSA auth response: %d", type);
|
|
debug("Rhosts or /etc/hosts.equiv with RSA host authentication refused.");
|
|
return 0;
|
|
}
|
|
|
|
#ifdef KRB4
|
|
int try_kerberos_authentication()
|
|
{
|
|
KTEXT_ST auth; /* Kerberos data */
|
|
char *reply;
|
|
char inst[INST_SZ];
|
|
char *realm;
|
|
CREDENTIALS cred;
|
|
int r, type, plen;
|
|
Key_schedule schedule;
|
|
u_long checksum, cksum;
|
|
MSG_DAT msg_data;
|
|
struct sockaddr_in local, foreign;
|
|
struct stat st;
|
|
|
|
/* Don't do anything if we don't have any tickets. */
|
|
if (stat(tkt_string(), &st) < 0) return 0;
|
|
|
|
strncpy(inst, (char *) krb_get_phost(get_canonical_hostname()), INST_SZ);
|
|
|
|
realm = (char *)krb_realmofhost(get_canonical_hostname());
|
|
if (!realm) {
|
|
debug("Kerberos V4: no realm for %s", get_canonical_hostname());
|
|
return 0;
|
|
}
|
|
/* This can really be anything. */
|
|
checksum = (u_long) getpid();
|
|
|
|
r = krb_mk_req(&auth, KRB4_SERVICE_NAME, inst, realm, checksum);
|
|
if (r != KSUCCESS) {
|
|
debug("Kerberos V4 krb_mk_req failed: %s", krb_err_txt[r]);
|
|
return 0;
|
|
}
|
|
/* Get session key to decrypt the server's reply with. */
|
|
r = krb_get_cred(KRB4_SERVICE_NAME, inst, realm, &cred);
|
|
if (r != KSUCCESS) {
|
|
debug("get_cred failed: %s", krb_err_txt[r]);
|
|
return 0;
|
|
}
|
|
des_key_sched((des_cblock *)cred.session, schedule);
|
|
|
|
/* Send authentication info to server. */
|
|
packet_start(SSH_CMSG_AUTH_KERBEROS);
|
|
packet_put_string((char *)auth.dat, auth.length);
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
/* Zero the buffer. */
|
|
(void) memset(auth.dat, 0, MAX_KTXT_LEN);
|
|
|
|
r = sizeof(local);
|
|
memset(&local, 0, sizeof(local));
|
|
if (getsockname(packet_get_connection_in(),
|
|
(struct sockaddr *) &local, &r) < 0)
|
|
debug("getsockname failed: %s", strerror(errno));
|
|
|
|
r = sizeof(foreign);
|
|
memset(&foreign, 0, sizeof(foreign));
|
|
if (getpeername(packet_get_connection_in(),
|
|
(struct sockaddr *)&foreign, &r) < 0)
|
|
debug("getpeername failed: %s", strerror(errno));
|
|
|
|
/* Get server reply. */
|
|
type = packet_read(&plen);
|
|
switch(type) {
|
|
|
|
case SSH_SMSG_FAILURE: /* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */
|
|
debug("Kerberos V4 authentication failed.");
|
|
return 0;
|
|
break;
|
|
|
|
case SSH_SMSG_AUTH_KERBEROS_RESPONSE: /* SSH_SMSG_AUTH_KERBEROS_SUCCESS */
|
|
debug("Kerberos V4 authentication accepted.");
|
|
|
|
/* Get server's response. */
|
|
reply = packet_get_string((unsigned int *)&auth.length);
|
|
memcpy(auth.dat, reply, auth.length);
|
|
xfree(reply);
|
|
|
|
packet_integrity_check(plen, 4 + auth.length, type);
|
|
|
|
/* If his response isn't properly encrypted with the session key,
|
|
and the decrypted checksum fails to match, he's bogus. Bail out. */
|
|
r = krb_rd_priv(auth.dat, auth.length, schedule, &cred.session,
|
|
&foreign, &local, &msg_data);
|
|
if (r != KSUCCESS) {
|
|
debug("Kerberos V4 krb_rd_priv failed: %s", krb_err_txt[r]);
|
|
packet_disconnect("Kerberos V4 challenge failed!");
|
|
}
|
|
/* Fetch the (incremented) checksum that we supplied in the request. */
|
|
(void)memcpy((char *)&cksum, (char *)msg_data.app_data, sizeof(cksum));
|
|
cksum = ntohl(cksum);
|
|
|
|
/* If it matches, we're golden. */
|
|
if (cksum == checksum + 1) {
|
|
debug("Kerberos V4 challenge successful.");
|
|
return 1;
|
|
}
|
|
else
|
|
packet_disconnect("Kerberos V4 challenge failed!");
|
|
break;
|
|
|
|
default:
|
|
packet_disconnect("Protocol error on Kerberos V4 response: %d", type);
|
|
}
|
|
return 0;
|
|
}
|
|
#endif /* KRB4 */
|
|
|
|
#ifdef AFS
|
|
int send_kerberos_tgt()
|
|
{
|
|
CREDENTIALS *creds;
|
|
char pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ];
|
|
int r, type, plen;
|
|
unsigned char buffer[8192];
|
|
struct stat st;
|
|
|
|
/* Don't do anything if we don't have any tickets. */
|
|
if (stat(tkt_string(), &st) < 0) return 0;
|
|
|
|
creds = xmalloc(sizeof(*creds));
|
|
|
|
if ((r = krb_get_tf_fullname(TKT_FILE, pname, pinst, prealm)) != KSUCCESS) {
|
|
debug("Kerberos V4 tf_fullname failed: %s",krb_err_txt[r]);
|
|
return 0;
|
|
}
|
|
if ((r = krb_get_cred("krbtgt", prealm, prealm, creds)) != GC_OK) {
|
|
debug("Kerberos V4 get_cred failed: %s", krb_err_txt[r]);
|
|
return 0;
|
|
}
|
|
if (time(0) > krb_life_to_time(creds->issue_date, creds->lifetime)) {
|
|
debug("Kerberos V4 ticket expired: %s", TKT_FILE);
|
|
return 0;
|
|
}
|
|
|
|
creds_to_radix(creds, buffer);
|
|
xfree(creds);
|
|
|
|
packet_start(SSH_CMSG_HAVE_KERBEROS_TGT);
|
|
packet_put_string((char *)buffer, strlen(buffer));
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
type = packet_read(&plen);
|
|
|
|
if (type == SSH_SMSG_FAILURE)
|
|
debug("Kerberos TGT for realm %s rejected.", prealm);
|
|
else if (type != SSH_SMSG_SUCCESS)
|
|
packet_disconnect("Protocol error on Kerberos TGT response: %d", type);
|
|
|
|
return 1;
|
|
}
|
|
|
|
void send_afs_tokens(void)
|
|
{
|
|
CREDENTIALS creds;
|
|
struct ViceIoctl parms;
|
|
struct ClearToken ct;
|
|
int i, type, len, plen;
|
|
char buf[2048], *p, *server_cell;
|
|
unsigned char buffer[8192];
|
|
|
|
/* Move over ktc_GetToken, here's something leaner. */
|
|
for (i = 0; i < 100; i++) { /* just in case */
|
|
parms.in = (char *)&i;
|
|
parms.in_size = sizeof(i);
|
|
parms.out = buf;
|
|
parms.out_size = sizeof(buf);
|
|
if (k_pioctl(0, VIOCGETTOK, &parms, 0) != 0) break;
|
|
p = buf;
|
|
|
|
/* Get secret token. */
|
|
memcpy(&creds.ticket_st.length, p, sizeof(unsigned int));
|
|
if (creds.ticket_st.length > MAX_KTXT_LEN) break;
|
|
p += sizeof(unsigned int);
|
|
memcpy(creds.ticket_st.dat, p, creds.ticket_st.length);
|
|
p += creds.ticket_st.length;
|
|
|
|
/* Get clear token. */
|
|
memcpy(&len, p, sizeof(len));
|
|
if (len != sizeof(struct ClearToken)) break;
|
|
p += sizeof(len);
|
|
memcpy(&ct, p, len);
|
|
p += len;
|
|
p += sizeof(len); /* primary flag */
|
|
server_cell = p;
|
|
|
|
/* Flesh out our credentials. */
|
|
strlcpy(creds.service, "afs", sizeof creds.service);
|
|
creds.instance[0] = '\0';
|
|
strlcpy(creds.realm, server_cell, REALM_SZ);
|
|
memcpy(creds.session, ct.HandShakeKey, DES_KEY_SZ);
|
|
creds.issue_date = ct.BeginTimestamp;
|
|
creds.lifetime = krb_time_to_life(creds.issue_date, ct.EndTimestamp);
|
|
creds.kvno = ct.AuthHandle;
|
|
snprintf(creds.pname, sizeof(creds.pname), "AFS ID %d", ct.ViceId);
|
|
creds.pinst[0] = '\0';
|
|
|
|
/* Encode token, ship it off. */
|
|
if (!creds_to_radix(&creds, buffer)) break;
|
|
packet_start(SSH_CMSG_HAVE_AFS_TOKEN);
|
|
packet_put_string((char *)buffer, strlen(buffer));
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
/* Roger, Roger. Clearance, Clarence. What's your vector, Victor? */
|
|
type = packet_read(&plen);
|
|
|
|
if (type == SSH_SMSG_FAILURE)
|
|
debug("AFS token for cell %s rejected.", server_cell);
|
|
else if (type != SSH_SMSG_SUCCESS)
|
|
packet_disconnect("Protocol error on AFS token response: %d", type);
|
|
}
|
|
}
|
|
#endif /* AFS */
|
|
|
|
/* Waits for the server identification string, and sends our own identification
|
|
string. */
|
|
|
|
void ssh_exchange_identification()
|
|
{
|
|
char buf[256], remote_version[256]; /* must be same size! */
|
|
int remote_major, remote_minor, i;
|
|
int connection_in = packet_get_connection_in();
|
|
int connection_out = packet_get_connection_out();
|
|
extern Options options;
|
|
|
|
/* Read other side\'s version identification. */
|
|
for (i = 0; i < sizeof(buf) - 1; i++)
|
|
{
|
|
if (read(connection_in, &buf[i], 1) != 1)
|
|
fatal("read: %.100s", strerror(errno));
|
|
if (buf[i] == '\r')
|
|
{
|
|
buf[i] = '\n';
|
|
buf[i + 1] = 0;
|
|
break;
|
|
}
|
|
if (buf[i] == '\n')
|
|
{
|
|
buf[i + 1] = 0;
|
|
break;
|
|
}
|
|
}
|
|
buf[sizeof(buf) - 1] = 0;
|
|
|
|
/* Check that the versions match. In future this might accept several
|
|
versions and set appropriate flags to handle them. */
|
|
if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", &remote_major, &remote_minor,
|
|
remote_version) != 3)
|
|
fatal("Bad remote protocol version identification: '%.100s'", buf);
|
|
debug("Remote protocol version %d.%d, remote software version %.100s",
|
|
remote_major, remote_minor, remote_version);
|
|
|
|
/* Check if the remote protocol version is too old. */
|
|
if (remote_major == 1 && remote_minor < 3)
|
|
fatal("Remote machine has too old SSH software version.");
|
|
|
|
/* We speak 1.3, too. */
|
|
if (remote_major == 1 && remote_minor == 3) {
|
|
enable_compat13();
|
|
if (options.forward_agent && strcmp(remote_version, SSH_VERSION) != 0) {
|
|
log("Agent forwarding disabled, remote version '%s' is not compatible.",
|
|
remote_version);
|
|
options.forward_agent = 0;
|
|
}
|
|
}
|
|
#if 0
|
|
/* Removed for now, to permit compatibility with latter versions. The server
|
|
will reject our version and disconnect if it doesn't support it. */
|
|
if (remote_major != PROTOCOL_MAJOR)
|
|
fatal("Protocol major versions differ: %d vs. %d",
|
|
PROTOCOL_MAJOR, remote_major);
|
|
#endif
|
|
|
|
/* Send our own protocol version identification. */
|
|
snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
|
|
PROTOCOL_MAJOR, PROTOCOL_MINOR, SSH_VERSION);
|
|
if (write(connection_out, buf, strlen(buf)) != strlen(buf))
|
|
fatal("write: %.100s", strerror(errno));
|
|
}
|
|
|
|
int ssh_cipher_default = SSH_CIPHER_3DES;
|
|
|
|
int read_yes_or_no(const char *prompt, int defval)
|
|
{
|
|
char buf[1024];
|
|
FILE *f;
|
|
int retval = -1;
|
|
|
|
if (isatty(0))
|
|
f = stdin;
|
|
else
|
|
f = fopen("/dev/tty", "rw");
|
|
|
|
if (f == NULL)
|
|
return 0;
|
|
|
|
fflush(stdout);
|
|
|
|
while (1)
|
|
{
|
|
fprintf(stderr, "%s", prompt);
|
|
if (fgets(buf, sizeof(buf), f) == NULL)
|
|
{
|
|
/* Print a newline (the prompt probably didn\'t have one). */
|
|
fprintf(stderr, "\n");
|
|
strlcpy(buf, "no", sizeof buf);
|
|
}
|
|
/* Remove newline from response. */
|
|
if (strchr(buf, '\n'))
|
|
*strchr(buf, '\n') = 0;
|
|
|
|
if (buf[0] == 0)
|
|
retval = defval;
|
|
if (strcmp(buf, "yes") == 0)
|
|
retval = 1;
|
|
if (strcmp(buf, "no") == 0)
|
|
retval = 0;
|
|
|
|
if (retval != -1)
|
|
{
|
|
if (f != stdin)
|
|
fclose(f);
|
|
return retval;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* 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.
|
|
User is the remote user; if it is NULL, the current local user name will
|
|
be used. Anonymous indicates that no rhosts authentication will be used.
|
|
If login fails, this function prints an error and never returns.
|
|
This function does not require super-user privileges. */
|
|
|
|
void ssh_login(int host_key_valid,
|
|
RSA *own_host_key,
|
|
const char *orighost,
|
|
struct sockaddr_in *hostaddr,
|
|
Options *options, uid_t original_real_uid)
|
|
{
|
|
int i, type;
|
|
char *password;
|
|
struct passwd *pw;
|
|
BIGNUM *key;
|
|
RSA *host_key, *file_key;
|
|
RSA *public_key;
|
|
unsigned char session_key[SSH_SESSION_KEY_LENGTH];
|
|
const char *server_user, *local_user;
|
|
char *cp, *host, *ip = NULL;
|
|
unsigned char check_bytes[8];
|
|
unsigned int supported_ciphers, supported_authentications, protocol_flags;
|
|
HostStatus host_status;
|
|
HostStatus ip_status;
|
|
int host_ip_differ = 0;
|
|
int local = (ntohl(hostaddr->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
|
|
int payload_len, clen, sum_len = 0;
|
|
u_int32_t rand = 0;
|
|
|
|
if (options->check_host_ip)
|
|
ip = xstrdup(inet_ntoa(hostaddr->sin_addr));
|
|
|
|
/* 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();
|
|
|
|
/* Get local user name. Use it as server user if no user name
|
|
was given. */
|
|
pw = getpwuid(original_real_uid);
|
|
if (!pw)
|
|
fatal("User id %d not found from user database.", original_real_uid);
|
|
local_user = xstrdup(pw->pw_name);
|
|
server_user = options->user ? options->user : local_user;
|
|
|
|
debug("Waiting for server public key.");
|
|
|
|
/* Wait for a public key packet from the server. */
|
|
packet_read_expect(&payload_len, SSH_SMSG_PUBLIC_KEY);
|
|
|
|
/* Get check bytes from the packet. */
|
|
for (i = 0; i < 8; i++)
|
|
check_bytes[i] = packet_get_char();
|
|
|
|
/* Get the public key. */
|
|
public_key = RSA_new();
|
|
packet_get_int(); /* bits */
|
|
public_key->e = BN_new();
|
|
packet_get_bignum(public_key->e, &clen);
|
|
sum_len += clen;
|
|
public_key->n = BN_new();
|
|
packet_get_bignum(public_key->n, &clen);
|
|
sum_len += clen;
|
|
|
|
/* Get the host key. */
|
|
host_key = RSA_new();
|
|
packet_get_int(); /* bits */
|
|
host_key->e = BN_new();
|
|
packet_get_bignum(host_key->e, &clen);
|
|
sum_len += clen;
|
|
host_key->n = BN_new();
|
|
packet_get_bignum(host_key->n, &clen);
|
|
sum_len += clen;
|
|
|
|
/* 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 = RSA_new();
|
|
file_key->n = BN_new();
|
|
file_key->e = BN_new();
|
|
|
|
/* Get protocol flags. */
|
|
protocol_flags = packet_get_int();
|
|
packet_set_protocol_flags(protocol_flags);
|
|
|
|
/* Get supported cipher types. */
|
|
supported_ciphers = packet_get_int();
|
|
|
|
/* Get supported authentication types. */
|
|
supported_authentications = packet_get_int();
|
|
|
|
debug("Received server public key (%d bits) and host key (%d bits).",
|
|
BN_num_bits(public_key->n), BN_num_bits(host_key->n));
|
|
|
|
packet_integrity_check(payload_len,
|
|
8 + 4 + sum_len + 0 + 4 + 0 + 0 + 4 + 4 + 4,
|
|
SSH_SMSG_PUBLIC_KEY);
|
|
|
|
/* Compute the session id. */
|
|
compute_session_id(session_id, check_bytes,
|
|
BN_num_bits(host_key->n), host_key->n,
|
|
BN_num_bits(public_key->n), public_key->n);
|
|
|
|
/* Check if the host key is present in the user\'s list of known hosts
|
|
or in the systemwide list. */
|
|
host_status = check_host_in_hostfile(options->user_hostfile,
|
|
host, BN_num_bits(host_key->n),
|
|
host_key->e, host_key->n,
|
|
file_key->e, file_key->n);
|
|
if (host_status == HOST_NEW)
|
|
host_status = check_host_in_hostfile(options->system_hostfile, host,
|
|
BN_num_bits(host_key->n),
|
|
host_key->e, host_key->n,
|
|
file_key->e, file_key->n);
|
|
/* Force accepting of the host key for localhost and 127.0.0.1.
|
|
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. */
|
|
if (local) {
|
|
debug("Forcing accepting of host key for localhost.");
|
|
host_status = HOST_OK;
|
|
}
|
|
|
|
/* 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 && !local && strcmp(host, ip)) {
|
|
RSA *ip_key = RSA_new();
|
|
ip_key->n = BN_new();
|
|
ip_key->e = BN_new();
|
|
ip_status = check_host_in_hostfile(options->user_hostfile, ip,
|
|
BN_num_bits(host_key->n),
|
|
host_key->e, host_key->n,
|
|
ip_key->e, ip_key->n);
|
|
|
|
if (ip_status == HOST_NEW)
|
|
ip_status = check_host_in_hostfile(options->system_hostfile, ip,
|
|
BN_num_bits(host_key->n),
|
|
host_key->e, host_key->n,
|
|
ip_key->e, ip_key->n);
|
|
if (host_status == HOST_CHANGED &&
|
|
(ip_status != HOST_CHANGED ||
|
|
(BN_cmp(ip_key->e, file_key->e) || BN_cmp(ip_key->n, file_key->n))))
|
|
host_ip_differ = 1;
|
|
|
|
RSA_free(ip_key);
|
|
} else
|
|
ip_status = host_status;
|
|
|
|
RSA_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 host key.", host);
|
|
if (options->check_host_ip) {
|
|
if (ip_status == HOST_NEW) {
|
|
if (!add_host_to_hostfile(options->user_hostfile, ip,
|
|
BN_num_bits(host_key->n),
|
|
host_key->e, host_key->n))
|
|
log("Failed to add the host ip to the list of known hosts (%.30s).",
|
|
options->user_hostfile);
|
|
else
|
|
log("Warning: Permanently added host ip '%.30s' to the list of known hosts.", ip);
|
|
} else if (ip_status != HOST_OK)
|
|
log("Warning: the host key differ from the key of the ip address '%.30s' differs", ip);
|
|
}
|
|
|
|
break;
|
|
case HOST_NEW:
|
|
{
|
|
char hostline[1000], *hostp = hostline;
|
|
/* 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. */
|
|
fatal("No host key is known for %.200s and you have requested strict checking.", host);
|
|
} else if (options->strict_host_key_checking == 2) { /* The default */
|
|
char prompt[1024];
|
|
snprintf(prompt, sizeof(prompt),
|
|
"The authenticity of host '%.200s' can't be established.\n"
|
|
"Are you sure you want to continue connecting (yes/no)? ",
|
|
host);
|
|
if (!read_yes_or_no(prompt, -1))
|
|
fatal("Aborted by user!\n");
|
|
}
|
|
|
|
if (options->check_host_ip && ip_status == HOST_NEW && strcmp(host, ip))
|
|
snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
|
|
else
|
|
hostp = host;
|
|
|
|
/* If not in strict mode, add the key automatically to the local
|
|
known_hosts file. */
|
|
if (!add_host_to_hostfile(options->user_hostfile, hostp,
|
|
BN_num_bits(host_key->n),
|
|
host_key->e, host_key->n))
|
|
log("Failed to add the host to the list of known hosts (%.500s).",
|
|
options->user_hostfile);
|
|
else
|
|
log("Warning: Permanently added '%.200s' to the list of known hosts.",
|
|
hostp);
|
|
break;
|
|
}
|
|
case HOST_CHANGED:
|
|
if (options->check_host_ip) {
|
|
if (host_ip_differ) {
|
|
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
|
|
error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
|
|
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
|
|
error("The host key for %s has changed,", host);
|
|
error("but the key for the according IP address %s has", ip);
|
|
error("a different status. This could either mean that DNS");
|
|
error("SPOOFING is happening or the IP address for the host");
|
|
error("and its host key have changed at the same time");
|
|
}
|
|
}
|
|
|
|
/* The host key has changed. */
|
|
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
|
|
error("@ WARNING: 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 host key has just been changed.");
|
|
error("Please contact your system administrator.");
|
|
error("Add correct host key in %.100s to get rid of this message.",
|
|
options->user_hostfile);
|
|
|
|
/* 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)
|
|
fatal("Host key for %.200s has changed and you have requested strict checking.", host);
|
|
|
|
/* 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 trojan horses.");
|
|
options->password_authentication = 0;
|
|
}
|
|
if (options->forward_agent) {
|
|
error("Agent forwarding is disabled to avoid trojan horses.");
|
|
options->forward_agent = 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)
|
|
xfree(ip);
|
|
|
|
/* Generate a session key. */
|
|
arc4random_stir();
|
|
|
|
/* Generate an encryption key for the session. The key is a 256 bit
|
|
random number, interpreted as a 32-byte key, with the least significant
|
|
8 bits being the first byte of the key. */
|
|
for (i = 0; i < 32; i++) {
|
|
if (i % 4 == 0)
|
|
rand = arc4random();
|
|
session_key[i] = rand & 0xff;
|
|
rand >>= 8;
|
|
}
|
|
|
|
/* According to the protocol spec, the first byte of the session key is
|
|
the highest byte of the integer. The session key is xored with the
|
|
first 16 bytes of the session id. */
|
|
key = BN_new();
|
|
BN_set_word(key, 0);
|
|
for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++)
|
|
{
|
|
BN_lshift(key, key, 8);
|
|
if (i < 16)
|
|
BN_add_word(key, session_key[i] ^ session_id[i]);
|
|
else
|
|
BN_add_word(key, session_key[i]);
|
|
}
|
|
|
|
/* Encrypt the integer using the public key and host key of the server
|
|
(key with smaller modulus first). */
|
|
if (BN_cmp(public_key->n, host_key->n) < 0)
|
|
{
|
|
/* Public key has smaller modulus. */
|
|
if (BN_num_bits(host_key->n) <
|
|
BN_num_bits(public_key->n) + SSH_KEY_BITS_RESERVED) {
|
|
fatal("respond_to_rsa_challenge: host_key %d < public_key %d + "
|
|
"SSH_KEY_BITS_RESERVED %d",
|
|
BN_num_bits(host_key->n),
|
|
BN_num_bits(public_key->n),
|
|
SSH_KEY_BITS_RESERVED);
|
|
}
|
|
|
|
rsa_public_encrypt(key, key, public_key);
|
|
rsa_public_encrypt(key, key, host_key);
|
|
}
|
|
else
|
|
{
|
|
/* Host key has smaller modulus (or they are equal). */
|
|
if (BN_num_bits(public_key->n) <
|
|
BN_num_bits(host_key->n) + SSH_KEY_BITS_RESERVED) {
|
|
fatal("respond_to_rsa_challenge: public_key %d < host_key %d + "
|
|
"SSH_KEY_BITS_RESERVED %d",
|
|
BN_num_bits(public_key->n),
|
|
BN_num_bits(host_key->n),
|
|
SSH_KEY_BITS_RESERVED);
|
|
}
|
|
|
|
rsa_public_encrypt(key, key, host_key);
|
|
rsa_public_encrypt(key, key, public_key);
|
|
}
|
|
|
|
if (options->cipher == SSH_CIPHER_NOT_SET) {
|
|
if (cipher_mask() & supported_ciphers & (1 << ssh_cipher_default))
|
|
options->cipher = ssh_cipher_default;
|
|
else {
|
|
debug("Cipher %d not supported, using %.100s instead.",
|
|
cipher_name(ssh_cipher_default),
|
|
cipher_name(SSH_FALLBACK_CIPHER));
|
|
options->cipher = SSH_FALLBACK_CIPHER;
|
|
}
|
|
}
|
|
|
|
/* Check that the selected cipher is supported. */
|
|
if (!(supported_ciphers & (1 << options->cipher)))
|
|
fatal("Selected cipher type %.100s not supported by server.",
|
|
cipher_name(options->cipher));
|
|
|
|
debug("Encryption type: %.100s", cipher_name(options->cipher));
|
|
|
|
/* Send the encrypted session key to the server. */
|
|
packet_start(SSH_CMSG_SESSION_KEY);
|
|
packet_put_char(options->cipher);
|
|
|
|
/* Send the check bytes back to the server. */
|
|
for (i = 0; i < 8; i++)
|
|
packet_put_char(check_bytes[i]);
|
|
|
|
/* Send the encrypted encryption key. */
|
|
packet_put_bignum(key);
|
|
|
|
/* Send protocol flags. */
|
|
packet_put_int(SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
|
|
|
|
/* Send the packet now. */
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
/* Destroy the session key integer and the public keys since we no longer
|
|
need them. */
|
|
BN_clear_free(key);
|
|
RSA_free(public_key);
|
|
RSA_free(host_key);
|
|
|
|
debug("Sent encrypted session key.");
|
|
|
|
/* Set the encryption key. */
|
|
packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH,
|
|
options->cipher, 1);
|
|
|
|
/* We will no longer need the session key here. Destroy any extra copies. */
|
|
memset(session_key, 0, sizeof(session_key));
|
|
|
|
/* Expect a success message from the server. Note that this message will
|
|
be received in encrypted form. */
|
|
packet_read_expect(&payload_len, SSH_SMSG_SUCCESS);
|
|
|
|
debug("Received encrypted confirmation.");
|
|
|
|
/* Send the name of the user to log in as on the server. */
|
|
packet_start(SSH_CMSG_USER);
|
|
packet_put_string(server_user, strlen(server_user));
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
/* The server should respond with success if no authentication is needed
|
|
(the user has no password). Otherwise the server responds with
|
|
failure. */
|
|
type = packet_read(&payload_len);
|
|
if (type == SSH_SMSG_SUCCESS)
|
|
return; /* Connection was accepted without authentication. */
|
|
if (type != SSH_SMSG_FAILURE)
|
|
packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER",
|
|
type);
|
|
|
|
#ifdef AFS
|
|
/* Try Kerberos tgt passing if the server supports it. */
|
|
if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) &&
|
|
options->kerberos_tgt_passing)
|
|
{
|
|
if (options->cipher == SSH_CIPHER_NONE)
|
|
log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!");
|
|
(void)send_kerberos_tgt();
|
|
}
|
|
|
|
/* Try AFS token passing if the server supports it. */
|
|
if ((supported_authentications & (1 << SSH_PASS_AFS_TOKEN)) &&
|
|
options->afs_token_passing && k_hasafs()) {
|
|
if (options->cipher == SSH_CIPHER_NONE)
|
|
log("WARNING: Encryption is disabled! Token will be transmitted in the clear!");
|
|
send_afs_tokens();
|
|
}
|
|
#endif /* AFS */
|
|
|
|
#ifdef KRB4
|
|
if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) &&
|
|
options->kerberos_authentication)
|
|
{
|
|
debug("Trying Kerberos authentication.");
|
|
if (try_kerberos_authentication()) {
|
|
/* The server should respond with success or failure. */
|
|
type = packet_read(&payload_len);
|
|
if (type == SSH_SMSG_SUCCESS)
|
|
return; /* Successful connection. */
|
|
if (type != SSH_SMSG_FAILURE)
|
|
packet_disconnect("Protocol error: got %d in response to Kerberos auth", type);
|
|
}
|
|
}
|
|
#endif /* KRB4 */
|
|
|
|
/* Use rhosts authentication if running in privileged socket and we do not
|
|
wish to remain anonymous. */
|
|
if ((supported_authentications & (1 << SSH_AUTH_RHOSTS)) &&
|
|
options->rhosts_authentication)
|
|
{
|
|
debug("Trying rhosts authentication.");
|
|
packet_start(SSH_CMSG_AUTH_RHOSTS);
|
|
packet_put_string(local_user, strlen(local_user));
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
/* The server should respond with success or failure. */
|
|
type = packet_read(&payload_len);
|
|
if (type == SSH_SMSG_SUCCESS)
|
|
return; /* Successful connection. */
|
|
if (type != SSH_SMSG_FAILURE)
|
|
packet_disconnect("Protocol error: got %d in response to rhosts auth",
|
|
type);
|
|
}
|
|
|
|
/* Try .rhosts or /etc/hosts.equiv authentication with RSA host
|
|
authentication. */
|
|
if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) &&
|
|
options->rhosts_rsa_authentication && host_key_valid)
|
|
{
|
|
if (try_rhosts_rsa_authentication(local_user, own_host_key))
|
|
return; /* Successful authentication. */
|
|
}
|
|
|
|
/* Try RSA authentication if the server supports it. */
|
|
if ((supported_authentications & (1 << SSH_AUTH_RSA)) &&
|
|
options->rsa_authentication)
|
|
{
|
|
/* Try RSA authentication using the authentication agent. The agent
|
|
is tried first because no passphrase is needed for it, whereas
|
|
identity files may require passphrases. */
|
|
if (try_agent_authentication())
|
|
return; /* Successful connection. */
|
|
|
|
/* Try RSA authentication for each identity. */
|
|
for (i = 0; i < options->num_identity_files; i++)
|
|
if (try_rsa_authentication(pw, options->identity_files[i],
|
|
!options->batch_mode))
|
|
return; /* Successful connection. */
|
|
}
|
|
|
|
/* Try password authentication if the server supports it. */
|
|
if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) &&
|
|
options->password_authentication && !options->batch_mode)
|
|
{
|
|
char prompt[80];
|
|
snprintf(prompt, sizeof(prompt), "%.30s@%.30s's password: ",
|
|
server_user, host);
|
|
debug("Doing password authentication.");
|
|
if (options->cipher == SSH_CIPHER_NONE)
|
|
log("WARNING: Encryption is disabled! Password will be transmitted in clear text.");
|
|
for (i = 0; i < options->number_of_password_prompts; i++) {
|
|
if (i != 0)
|
|
error("Permission denied, please try again.");
|
|
password = read_passphrase(prompt, 0);
|
|
packet_start(SSH_CMSG_AUTH_PASSWORD);
|
|
packet_put_string(password, strlen(password));
|
|
memset(password, 0, strlen(password));
|
|
xfree(password);
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
type = packet_read(&payload_len);
|
|
if (type == SSH_SMSG_SUCCESS)
|
|
return; /* Successful connection. */
|
|
if (type != SSH_SMSG_FAILURE)
|
|
packet_disconnect("Protocol error: got %d in response to passwd auth", type);
|
|
}
|
|
}
|
|
|
|
/* All authentication methods have failed. Exit with an error message. */
|
|
fatal("Permission denied.");
|
|
/*NOTREACHED*/
|
|
}
|