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ck_ssh.c
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2001-11-30
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char *cksshv = "SSH support, 8.0.001, 13 Sep 2000";
/*
C K _ S S H . C -- OpenSSL Interface for C-Kermit
Copyright (C) 1985, 2001,
Trustees of Columbia University in the City of New York.
All rights reserved. See the C-Kermit COPYING.TXT file or the
copyright text in the ckcmai.c module for disclaimer and permissions.
Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
All rights reserved
Includes work by Niels Provos <provos@citi.umich.edu> to work with OpenSSL.
*/
#include "ckcdeb.h"
#ifdef SSH
#undef SSH
#endif /* SSH */
#ifdef CK_SSL
#ifdef SSH
#include <openssl/ssl.h>
#include <openssl/x509v3.h>
#include <openssl/rand.h>
#include <openssl/x509_vfy.h>
#include <openssl/err.h>
#include <openssl/bn.h>
#include <openssl/evp.h>
#include <openssl/dsa.h>
#include <openssl/rsa.h>
#ifdef OS2
#include "ckossl.h"
#endif /* OS2 */
static char *client_version_string = NULL;
static char *server_version_string = NULL;
/* Flag indicating whether IPv4 or IPv6.
This should be a SET TCP ... command. Need to look at supporting
IPv6 in ckcnet.c. AF_UNSPEC means both IPv4 and IPv6. */
static int IPv4or6 = AF_INET;
/* Flag indicating whether debug mode is on.
SET SSH DEBUG {ON, OFF }
*/
static int debug_flag = 0;
/* Flag indicating whether a tty should be allocated */
/* In other words, was Kermit started from a tty? */
static int tty_flag = 0;
/* don't exec a shell */
static int no_shell_flag = 0;
static int no_tty_flag = 0;
/*
* Flag indicating that nothing should be read from stdin.
* Not sure we should support this in Kermit
*/
static int stdin_null_flag = 0;
/*
* Flag indicating that ssh should fork after authentication. This is useful
* so that the pasphrase can be entered manually, and then ssh goes to the
* background. We will not support this in Kermit.
*/
static int fork_after_authentication_flag = 0;
/*
* General data structure for command line options and options configurable
* in configuration files.
*/
#define SSH_MAX_IDENTITY_FILES 100
#define SSH_MAX_FORWARDS_PER_DIRECTION 100
/* Data structure for representing a forwarding request. */
typedef struct {
u_short port; /* Port to forward. */
char *host; /* Host to connect. */
u_short host_port; /* Port to connect on host. */
} Forward;
/* Data structure for representing option data. */
typedef enum {
SYSLOG_LEVEL_QUIET,
SYSLOG_LEVEL_FATAL,
SYSLOG_LEVEL_ERROR,
SYSLOG_LEVEL_INFO,
SYSLOG_LEVEL_VERBOSE,
SYSLOG_LEVEL_DEBUG
} LogLevel;
typedef struct {
int forward_agent; /* Forward authentication agent. */
int forward_x11; /* Forward X11 display. */
char *xauth_location; /* Location for xauth program */
int gateway_ports; /* Allow remote connects to forwarded ports. */
int use_privileged_port; /* Don't use privileged port if false. *
int rhosts_authentication; /* Try rhosts authentication. */
int rhosts_rsa_authentication; /* Try rhosts with RSA
* authentication. */
int rsa_authentication; /* Try RSA authentication. */
int dsa_authentication; /* Try DSA authentication. */
int skey_authentication; /* Try S/Key or TIS authentication. */
#ifdef KRB4
int kerberos_authentication; /* Try Kerberos
* authentication. */
#endif
#ifdef AFS
int kerberos_tgt_passing; /* Try Kerberos tgt passing. */
int afs_token_passing; /* Try AFS token passing. */
#endif
int password_authentication; /* Try password
* authentication. */
int fallback_to_rsh;/* Use rsh if cannot connect with ssh. */
int use_rsh; /* Always use rsh (don\'t try ssh). */
int batch_mode; /* Batch mode: do not ask for passwords. */
int check_host_ip; /* Also keep track of keys for IP address */
int strict_host_key_checking; /* Strict host key checking. */
int compression; /* Compress packets in both directions. */
int compression_level; /* Compression level 1 (fast) to 9
* (best). */
int keepalives; /* Set SO_KEEPALIVE. */
LogLevel log_level; /* Level for logging. */
int port; /* Port to connect. */
int connection_attempts; /* Max attempts (seconds) before
* giving up */
int number_of_password_prompts; /* Max number of password
* prompts. */
int cipher; /* Cipher to use. */
char *ciphers; /* SSH2 ciphers in order of preference. */
int protocol; /* Protocol in order of preference. */
char *hostname; /* Real host to connect. */
char *proxy_command; /* Proxy command for connecting the host. */
char *user; /* User to log in as. */
int escape_char; /* Escape character; -2 = none */
char *system_hostfile;/* Path for /etc/ssh_known_hosts. */
char *user_hostfile; /* Path for $HOME/.ssh/known_hosts. */
char *system_hostfile2; char *user_hostfile2;
int num_identity_files; /* Number of files for RSA identities. *
int num_identity_files2; /* DSA identities. */
char *identity_files[SSH_MAX_IDENTITY_FILES];
char *identity_files2[SSH_MAX_IDENTITY_FILES];
/* Local TCP/IP forward requests. */
int num_local_forwards;
Forward local_forwards[SSH_MAX_FORWARDS_PER_DIRECTION];
/* Remote TCP/IP forward requests. */
int num_remote_forwards;
Forward remote_forwards[SSH_MAX_FORWARDS_PER_DIRECTION];
} Options;
static Options options;
/*
* Name of the host we are connecting to. This is the name given on the
* command line, or the HostName specified for the user-supplied name in a
* configuration file.
*/
static char *host;
/* socket address the host resolves to */
static struct sockaddr_storage hostaddr;
/*
* Flag to indicate that we have received a window change signal which has
* not yet been processed. This will cause a message indicating the new
* window size to be sent to the server a little later. This is volatile
* because this is updated in a signal handler.
*/
static volatile int received_window_change_signal = 0;
/* Value of argv[0] (set in the main program). */
static char *av0;
/* Flag indicating whether we have a valid host private key loaded. */
static int host_private_key_loaded = 0;
/* Host private key. */
static RSA *host_private_key = NULL;
/* Original real UID. */
static uid_t original_real_uid;
/* command to be executed */
static Buffer command;
/* SSH command line usage. Use this to design the Kermit "ssh" personality. */
/*
fprintf(stderr, "Usage: %s [options] host [command]\n", av0);
fprintf(stderr, "Options:\n");
fprintf(stderr, " -l user Log in using this user name.\n");
fprintf(stderr, " -n Redirect input from /dev/null.\n");
fprintf(stderr, " -A Enable authentication agent forwarding.\n");
fprintf(stderr, " -a Disable authentication agent forwarding.\n");
#ifdef AFS
fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n");
#endif /* AFS */
fprintf(stderr, " -X Enable X11 connection forwarding.\n");
fprintf(stderr, " -x Disable X11 connection forwarding.\n");
fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n");
fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n");
fprintf(stderr, " -T Do not allocate a tty.\n");
fprintf(stderr, " -v Verbose; display verbose debugging messages.\n");
fprintf(stderr, " -V Display version number only.\n");
fprintf(stderr, " -P Don't allocate a privileged port.\n");
fprintf(stderr, " -q Quiet; don't display any warning messages.\n");
fprintf(stderr, " -f Fork into background after authentication.\n");
fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n");
fprintf(stderr, " -c cipher Select encryption algorithm: "
"``3des'', "
"``blowfish''\n");
fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n");
fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n");
fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n");
fprintf(stderr, " These cause %s to listen for connections on a port, and\n", av0);
fprintf(stderr, " forward them to the other side by connecting to host:port.\n");
fprintf(stderr, " -C Enable compression.\n");
fprintf(stderr, " -N Do not execute a shell or command.\n");
fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n");
fprintf(stderr, " -4 Use IPv4 only.\n");
fprintf(stderr, " -6 Use IPv6 only.\n");
fprintf(stderr, " -2 Force protocol version 2.\n");
fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n");
*/
/* Function prototypes */
_PROTOTYP(static int ssh_session,(void));
_PROTOTYP(static int ssh_session2,(void));
_PROTOTYP(VOID client_set_session_ident,(int id));
/*
* Connects to the given host using rsh (or prints an error message and exits
* if rsh is not available). This function never returns.
*/
static void
rsh_connect(char *host, char *user, Buffer * command)
{
char *args[10];
int i;
log("Using rsh. WARNING: Connection will not be encrypted.");
/* Build argument list for rsh. */
i = 0;
args[i++] = _PATH_RSH;
/* host may have to come after user on some systems */
args[i++] = host;
if (user) {
args[i++] = "-l";
args[i++] = user;
}
if (buffer_len(command) > 0) {
buffer_append(command, "\0", 1);
args[i++] = buffer_ptr(command);
}
args[i++] = NULL;
if (debug_flag) {
for (i = 0; args[i]; i++) {
if (i != 0)
fprintf(stderr, " ");
fprintf(stderr, "%s", args[i]);
}
fprintf(stderr, "\n");
}
execv(_PATH_RSH, args);
perror(_PATH_RSH);
exit(1);
}
/*
* Main program for the ssh client.
*/
static int
main(int ac, char **av)
{
int i, opt, optind, exit_status, ok;
u_short fwd_port, fwd_host_port;
char *optarg, *cp, buf[256];
struct stat st;
struct passwd *pw, pwcopy;
int dummy;
uid_t original_effective_uid;
init_rng();
/*
* Save the original real uid. It will be needed later (uid-swapping
* may clobber the real uid).
*/
original_real_uid = getuid();
original_effective_uid = geteuid();
/* If we are installed setuid root be careful to not drop core. */
if (original_real_uid != original_effective_uid) {
struct rlimit rlim;
rlim.rlim_cur = rlim.rlim_max = 0;
if (setrlimit(RLIMIT_CORE, &rlim) < 0)
fatal("setrlimit failed: %.100s", strerror(errno));
}
/*
* Use uid-swapping to give up root privileges for the duration of
* option processing. We will re-instantiate the rights when we are
* ready to create the privileged port, and will permanently drop
* them when the port has been created (actually, when the connection
* has been made, as we may need to create the port several times).
*/
temporarily_use_uid(original_real_uid);
/*
* Set our umask to something reasonable, as some files are created
* with the default umask. This will make them world-readable but
* writable only by the owner, which is ok for all files for which we
* don't set the modes explicitly.
*/
umask(022);
/* Save our own name. */
av0 = av[0];
/* Initialize option structure to indicate that no values have been set. */
initialize_options(&options);
/* Parse command-line arguments. */
host = NULL;
/* If program name is not one of the standard names, use it as host name. */
if (strchr(av0, '/'))
cp = strrchr(av0, '/') + 1;
else
cp = av0;
if (strcmp(cp, "rsh") && strcmp(cp, "ssh") && strcmp(cp, "rlogin") &&
strcmp(cp, "slogin") && strcmp(cp, "remsh"))
host = cp;
for (optind = 1; optind < ac; optind++) {
if (av[optind][0] != '-') {
if (host)
break;
if ((cp = strchr(av[optind], '@'))) {
if(cp == av[optind])
usage();
options.user = av[optind];
*cp = '\0';
host = ++cp;
} else
host = av[optind];
continue;
}
opt = av[optind][1];
if (!opt)
usage();
if (strchr("eilcpLRo", opt)) { /* options with arguments */
optarg = av[optind] + 2;
if (strcmp(optarg, "") == 0) {
if (optind >= ac - 1)
usage();
optarg = av[++optind];
}
} else {
if (av[optind][2])
usage();
optarg = NULL;
}
switch (opt) {
case '2':
options.protocol = SSH_PROTO_2;
break;
case '4':
IPv4or6 = AF_INET;
break;
case '6':
IPv4or6 = AF_INET6;
break;
case 'n':
stdin_null_flag = 1;
break;
case 'f':
fork_after_authentication_flag = 1;
stdin_null_flag = 1;
break;
case 'x':
options.forward_x11 = 0;
break;
case 'X':
options.forward_x11 = 1;
break;
case 'g':
options.gateway_ports = 1;
break;
case 'P':
options.use_privileged_port = 0;
break;
case 'a':
options.forward_agent = 0;
break;
case 'A':
options.forward_agent = 1;
break;
#ifdef AFS
case 'k':
options.kerberos_tgt_passing = 0;
options.afs_token_passing = 0;
break;
#endif
case 'i':
if (stat(optarg, &st) < 0) {
fprintf(stderr, "Warning: Identity file %s does not exist.\n",
optarg);
break;
}
if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES)
fatal("Too many identity files specified (max %d)",
SSH_MAX_IDENTITY_FILES);
options.identity_files[options.num_identity_files++] =
xstrdup(optarg);
break;
case 't':
tty_flag = 1;
break;
case 'v':
case 'V':
fprintf(stderr, "SSH Version %s, protocol versions %d.%d/%d.%d.\n",
SSH_VERSION,
PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1,
PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2);
fprintf(stderr, "Compiled with SSL (0x%8.8lx).\n", SSLeay());
if (opt == 'V')
exit(0);
debug_flag = 1;
options.log_level = SYSLOG_LEVEL_DEBUG;
break;
case 'q':
options.log_level = SYSLOG_LEVEL_QUIET;
break;
case 'e':
if (optarg[0] == '^' && optarg[2] == 0 &&
(unsigned char) optarg[1] >= 64 && (unsigned char) optarg[1] < 128)
options.escape_char = (unsigned char) optarg[1] & 31;
else if (strlen(optarg) == 1)
options.escape_char = (unsigned char) optarg[0];
else if (strcmp(optarg, "none") == 0)
options.escape_char = -2;
else {
fprintf(stderr, "Bad escape character '%s'.\n", optarg);
exit(1);
}
break;
case 'c':
if (ciphers_valid(optarg)) {
/* SSH2 only */
options.ciphers = xstrdup(optarg);
options.cipher = SSH_CIPHER_ILLEGAL;
} else {
/* SSH1 only */
options.cipher = cipher_number(optarg);
if (options.cipher == -1) {
fprintf(stderr, "Unknown cipher type '%s'\n", optarg);
exit(1);
}
}
break;
case 'p':
options.port = atoi(optarg);
break;
case 'l':
options.user = optarg;
break;
case 'R':
if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf,
&fwd_host_port) != 3 &&
sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf,
&fwd_host_port) != 3) {
fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
usage();
/* NOTREACHED */
}
add_remote_forward(&options, fwd_port, buf, fwd_host_port);
break;
case 'L':
if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf,
&fwd_host_port) != 3 &&
sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf,
&fwd_host_port) != 3) {
fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
usage();
/* NOTREACHED */
}
add_local_forward(&options, fwd_port, buf, fwd_host_port);
break;
case 'C':
options.compression = 1;
break;
case 'N':
no_shell_flag = 1;
no_tty_flag = 1;
break;
case 'T':
no_tty_flag = 1;
break;
case 'o':
dummy = 1;
if (process_config_line(&options, host ? host : "", optarg,
"command-line", 0, &dummy) != 0)
exit(1);
break;
default:
usage();
}
}
/* Check that we got a host name. */
if (!host)
usage();
/* Initialize the command to execute on remote host. */
buffer_init(&command);
SSLeay_add_all_algorithms();
/*
* Save the command to execute on the remote host in a buffer. There
* is no limit on the length of the command, except by the maximum
* packet size. Also sets the tty flag if there is no command.
*/
if (optind == ac) {
/* No command specified - execute shell on a tty. */
tty_flag = 1;
} else {
/* A command has been specified. Store it into the
buffer. */
for (i = optind; i < ac; i++) {
if (i > optind)
buffer_append(&command, " ", 1);
buffer_append(&command, av[i], strlen(av[i]));
}
}
/* Cannot fork to background if no command. */
if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
fatal("Cannot fork into background without a command to execute.");
/* Allocate a tty by default if no command specified. */
if (buffer_len(&command) == 0)
tty_flag = 1;
/* Do not allocate a tty if stdin is not a tty. */
if (!isatty(fileno(stdin))) {
if (tty_flag)
fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n");
tty_flag = 0;
}
/* force */
if (no_tty_flag)
tty_flag = 0;
/* Get user data. */
pw = getpwuid(original_real_uid);
if (!pw) {
fprintf(stderr, "You don't exist, go away!\n");
exit(1);
}
/* Take a copy of the returned structure. */
memset(&pwcopy, 0, sizeof(pwcopy));
pwcopy.pw_name = xstrdup(pw->pw_name);
pwcopy.pw_passwd = xstrdup(pw->pw_passwd);
pwcopy.pw_uid = pw->pw_uid;
pwcopy.pw_gid = pw->pw_gid;
#ifdef HAVE_PW_CLASS_IN_PASSWD
pwcopy.pw_class = xstrdup(pw->pw_class);
#endif
pwcopy.pw_dir = xstrdup(pw->pw_dir);
pwcopy.pw_shell = xstrdup(pw->pw_shell);
pw = &pwcopy;
/* Initialize "log" output. Since we are the client all output
actually goes to the terminal. */
log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);
/* Read per-user configuration file. */
snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE);
read_config_file(buf, host, &options);
/* Read systemwide configuration file. */
read_config_file(HOST_CONFIG_FILE, host, &options);
/* Fill configuration defaults. */
fill_default_options(&options);
/* reinit */
log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);
/* check if RSA support exists */
if ((options.protocol & SSH_PROTO_1) &&
rsa_alive() == 0) {
log("%s: no RSA support in libssl and libcrypto. See ssl(8).",
__progname);
log("Disabling protocol version 1");
options.protocol &= ~ (SSH_PROTO_1|SSH_PROTO_1_PREFERRED);
}
if (! options.protocol & (SSH_PROTO_1|SSH_PROTO_2)) {
fprintf(stderr, "%s: No protocol version available.\n",
__progname);
exit(1);
}
if (options.user == NULL)
options.user = xstrdup(pw->pw_name);
if (options.hostname != NULL)
host = options.hostname;
/* Find canonic host name. */
if (strchr(host, '.') == 0) {
struct addrinfo hints;
struct addrinfo *ai = NULL;
int errgai;
memset(&hints, 0, sizeof(hints));
hints.ai_family = IPv4or6;
hints.ai_flags = AI_CANONNAME;
hints.ai_socktype = SOCK_STREAM;
errgai = getaddrinfo(host, NULL, &hints, &ai);
if (errgai == 0) {
if (ai->ai_canonname != NULL)
host = xstrdup(ai->ai_canonname);
freeaddrinfo(ai);
}
}
/* Disable rhosts authentication if not running as root. */
if (original_effective_uid != 0 || !options.use_privileged_port) {
options.rhosts_authentication = 0;
options.rhosts_rsa_authentication = 0;
}
/*
* If using rsh has been selected, exec it now (without trying
* anything else). Note that we must release privileges first.
*/
if (options.use_rsh) {
/*
* Restore our superuser privileges. This must be done
* before permanently setting the uid.
*/
restore_uid();
/* Switch to the original uid permanently. */
permanently_set_uid(original_real_uid);
/* Execute rsh. */
rsh_connect(host, options.user, &command);
fatal("rsh_connect returned");
}
/* Restore our superuser privileges. */
restore_uid();
/*
* Open a connection to the remote host. This needs root privileges
* if rhosts_{rsa_}authentication is enabled.
*/
ok = ssh_connect(host, &hostaddr, options.port,
options.connection_attempts,
!options.rhosts_authentication &&
!options.rhosts_rsa_authentication,
original_real_uid,
options.proxy_command);
/*
* If we successfully made the connection, load the host private key
* in case we will need it later for combined rsa-rhosts
* authentication. This must be done before releasing extra
* privileges, because the file is only readable by root.
*/
if (ok && (options.protocol & SSH_PROTO_1)) {
Key k;
host_private_key = RSA_new();
k.type = KEY_RSA;
k.rsa = host_private_key;
if (load_private_key(HOST_KEY_FILE, "", &k, NULL))
host_private_key_loaded = 1;
}
/*
* Get rid of any extra privileges that we may have. We will no
* longer need them. Also, extra privileges could make it very hard
* to read identity files and other non-world-readable files from the
* user's home directory if it happens to be on a NFS volume where
* root is mapped to nobody.
*/
/*
* Note that some legacy systems need to postpone the following call
* to permanently_set_uid() until the private hostkey is destroyed
* with RSA_free(). Otherwise the calling user could ptrace() the
* process, read the private hostkey and impersonate the host.
* OpenBSD does not allow ptracing of setuid processes.
*/
permanently_set_uid(original_real_uid);
/*
* Now that we are back to our own permissions, create ~/.ssh
* directory if it doesn\'t already exist.
*/
snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR);
if (stat(buf, &st) < 0)
if (mkdir(buf, 0700) < 0)
error("Could not create directory '%.200s'.", buf);
/* Check if the connection failed, and try "rsh" if appropriate. */
if (!ok) {
if (options.port != 0)
log("Secure connection to %.100s on port %hu refused%.100s.",
host, options.port,
options.fallback_to_rsh ? "; reverting to insecure method" : "");
else
log("Secure connection to %.100s refused%.100s.", host,
options.fallback_to_rsh ? "; reverting to insecure method" : "");
if (options.fallback_to_rsh) {
rsh_connect(host, options.user, &command);
fatal("rsh_connect returned");
}
exit(1);
}
/* Expand ~ in options.identity_files. */
/* XXX mem-leaks */
for (i = 0; i < options.num_identity_files; i++)
options.identity_files[i] =
tilde_expand_filename(options.identity_files[i], original_real_uid);
for (i = 0; i < options.num_identity_files2; i++)
options.identity_files2[i] =
tilde_expand_filename(options.identity_files2[i], original_real_uid);
/* Expand ~ in known host file names. */
options.system_hostfile = tilde_expand_filename(options.system_hostfile,
original_real_uid);
options.user_hostfile = tilde_expand_filename(options.user_hostfile,
original_real_uid);
options.system_hostfile2 = tilde_expand_filename(options.system_hostfile2,
original_real_uid);
options.user_hostfile2 = tilde_expand_filename(options.user_hostfile2,
original_real_uid);
/* Log into the remote system. This never returns if the login fails. */
ssh_login(host_private_key_loaded, host_private_key,
host, (struct sockaddr *)&hostaddr, original_real_uid);
/* We no longer need the host private key. Clear it now. */
if (host_private_key_loaded)
RSA_free(host_private_key); /* Destroys contents safely */
exit_status = compat20 ? ssh_session2() : ssh_session();
packet_close();
return exit_status;
}
static void
x11_get_proto(char *proto, int proto_len, char *data, int data_len)
{
char line[512];
FILE *f;
int got_data = 0, i;
if (options.xauth_location) {
/* Try to get Xauthority information for the display. */
snprintf(line, sizeof line, "%.100s list %.200s 2>/dev/null",
options.xauth_location, getenv("DISPLAY"));
f = popen(line, "r");
if (f && fgets(line, sizeof(line), f) &&
sscanf(line, "%*s %s %s", proto, data) == 2)
got_data = 1;
if (f)
pclose(f);
}
/*
* If we didn't get authentication data, just make up some
* data. The forwarding code will check the validity of the
* response anyway, and substitute this data. The X11
* server, however, will ignore this fake data and use
* whatever authentication mechanisms it was using otherwise
* for the local connection.
*/
if (!got_data) {
u_int32_t rand = 0;
strlcpy(proto, "MIT-MAGIC-COOKIE-1", proto_len);
for (i = 0; i < 16; i++) {
if (i % 4 == 0)
rand = arc4random();
snprintf(data + 2 * i, data_len - 2 * i, "%02x", rand & 0xff);
rand >>= 8;
}
}
}
static int
ssh_session(void)
{
int type;
int i;
int plen;
int interactive = 0;
int have_tty = 0;
struct winsize ws;
int authfd;
char *cp;
/* Enable compression if requested. */
if (options.compression) {
debug("Requesting compression at level %d.", options.compression_level);
if (options.compression_level < 1 || options.compression_level > 9)
fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
/* Send the request. */
packet_start(SSH_CMSG_REQUEST_COMPRESSION);
packet_put_int(options.compression_level);
packet_send();
packet_write_wait();
type = packet_read(&plen);
if (type == SSH_SMSG_SUCCESS)
packet_start_compression(options.compression_level);
else if (type == SSH_SMSG_FAILURE)
log("Warning: Remote host refused compression.");
else
packet_disconnect("Protocol error waiting for compression response.");
}
/* Allocate a pseudo tty if appropriate. */
if (tty_flag) {
debug("Requesting pty.");
/* Start the packet. */
packet_start(SSH_CMSG_REQUEST_PTY);
/* Store TERM in the packet. There is no limit on the
length of the string. */
cp = getenv("TERM");
if (!cp)
cp = "";
packet_put_string(cp, strlen(cp));
/* Store window size in the packet. */
if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
memset(&ws, 0, sizeof(ws));
packet_put_int(ws.ws_row);
packet_put_int(ws.ws_col);
packet_put_int(ws.ws_xpixel);
packet_put_int(ws.ws_ypixel);
/* Store tty modes in the packet. */
tty_make_modes(fileno(stdin));
/* Send the packet, and wait for it to leave. */
packet_send();
packet_write_wait();
/* Read response from the server. */
type = packet_read(&plen);
if (type == SSH_SMSG_SUCCESS) {
interactive = 1;
have_tty = 1;
} else if (type == SSH_SMSG_FAILURE)
log("Warning: Remote host failed or refused to allocate a pseudo tty.");
else
packet_disconnect("Protocol error waiting for pty request response.");
}
/* Request X11 forwarding if enabled and DISPLAY is set. */
if (options.forward_x11 && getenv("DISPLAY") != NULL) {
char proto[512], data[512];
/* Get reasonable local authentication information. */
x11_get_proto(proto, sizeof proto, data, sizeof data);
/* Request forwarding with authentication spoofing. */
debug("Requesting X11 forwarding with authentication spoofing.");
x11_request_forwarding_with_spoofing(0, proto, data);
/* Read response from the server. */
type = packet_read(&plen);
if (type == SSH_SMSG_SUCCESS) {
interactive = 1;
} else if (type == SSH_SMSG_FAILURE) {
log("Warning: Remote host denied X11 forwarding.");
} else {
packet_disconnect("Protocol error waiting for X11 forwarding");
}
}
/* Tell the packet module whether this is an interactive session. */
packet_set_interactive(interactive, options.keepalives);
/* Clear agent forwarding if we don\'t have an agent. */
authfd = ssh_get_authentication_socket();
if (authfd < 0)
options.forward_agent = 0;
else
ssh_close_authentication_socket(authfd);
/* Request authentication agent forwarding if appropriate. */
if (options.forward_agent) {
debug("Requesting authentication agent forwarding.");
auth_request_forwarding();
/* Read response from the server. */
type = packet_read(&plen);
packet_integrity_check(plen, 0, type);
if (type != SSH_SMSG_SUCCESS)
log("Warning: Remote host denied authentication agent forwarding.");
}
/* Initiate local TCP/IP port forwardings. */
for (i = 0; i < options.num_local_forwards; i++) {
debug("Connections to local port %d forwarded to remote address %.200s:%d",
options.local_forwards[i].port,
options.local_forwards[i].host,
options.local_forwards[i].host_port);
channel_request_local_forwarding(options.local_forwards[i].port,
options.local_forwards[i].host,
options.local_forwards[i].host_port,
options.gateway_ports);
}
/* Initiate remote TCP/IP port forwardings. */
for (i = 0; i < options.num_remote_forwards; i++) {
debug("Connections to remote port %d forwarded to local address %.200s:%d",
options.remote_forwards[i].port,
options.remote_forwards[i].host,
options.remote_forwards[i].host_port);
channel_request_remote_forwarding(options.remote_forwards[i].port,
options.remote_forwards[i].host,
options.remote_forwards[i].host_port);
}
/* If requested, let ssh continue in the background. */
if (fork_after_authentication_flag)
if (daemon(1, 1) < 0)
fatal("daemon() failed: %.200s", strerror(errno));
/*
* If a command was specified on the command line, execute the
* command now. Otherwise request the server to start a shell.
*/
if (buffer_len(&command) > 0) {
int len = buffer_len(&command);
if (len > 900)
len = 900;
debug("Sending command: %.*s", len, buffer_ptr(&command));
packet_start(SSH_CMSG_EXEC_CMD);
packet_put_string(buffer_ptr(&command), buffer_len(&command));
packet_send();
packet_write_wait();
} else {
debug("Requesting shell.");
packet_start(SSH_CMSG_EXEC_SHELL);
packet_send();
packet_write_wait();
}
/* Enter the interactive session. */
return client_loop(have_tty, tty_flag ? options.escape_char : -1, 0);
}
static void
init_local_fwd(void)
{
int i;
/* Initiate local TCP/IP port forwardings. */
for (i = 0; i < options.num_local_forwards; i++) {
debug("Connections to local port %d forwarded to remote address %.200s:%d",
options.local_forwards[i].port,
options.local_forwards[i].host,
options.local_forwards[i].host_port);
channel_request_local_forwarding(options.local_forwards[i].port,
options.local_forwards[i].host,
options.local_forwards[i].host_port,
options.gateway_ports);
}
}
static void
client_init(int id, void *arg)
{
int len;
debug("client_init id %d arg %d", id, (int)arg);
if (no_shell_flag)
goto done;
if (tty_flag) {
struct winsize ws;
char *cp;
cp = getenv("TERM");
if (!cp)
cp = "";
/* Store window size in the packet. */
if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
memset(&ws, 0, sizeof(ws));
channel_request_start(id, "pty-req", 0);
packet_put_cstring(cp);
packet_put_int(ws.ws_col);
packet_put_int(ws.ws_row);
packet_put_int(ws.ws_xpixel);
packet_put_int(ws.ws_ypixel);
packet_put_cstring(""); /* XXX: encode terminal modes */
packet_send();
/* XXX wait for reply */
}
if (options.forward_x11 &&
getenv("DISPLAY") != NULL) {
char proto[512], data[512];
/* Get reasonable local authentication information. */
x11_get_proto(proto, sizeof proto, data, sizeof data);
/* Request forwarding with authentication spoofing. */
debug("Requesting X11 forwarding with authentication spoofing.");
x11_request_forwarding_with_spoofing(id, proto, data);
/* XXX wait for reply */
}
len = buffer_len(&command);
if (len > 0) {
if (len > 900)
len = 900;
debug("Sending command: %.*s", len, buffer_ptr(&command));
channel_request_start(id, "exec", 0);
packet_put_string(buffer_ptr(&command), len);
packet_send();
} else {
channel_request(id, "shell", 0);
}
/* channel_callback(id, SSH2_MSG_OPEN_CONFIGMATION, client_init, 0); */
done:
/* register different callback, etc. XXX */
client_set_session_ident(id);
}
static int
ssh_session2(void)
{
int window, packetmax, id;
int in, out, err;
if (stdin_null_flag) {
in = open("/dev/null", O_RDONLY);
} else {
in = dup(STDIN_FILENO);
}
out = dup(STDOUT_FILENO);
err = dup(STDERR_FILENO);
if (in < 0 || out < 0 || err < 0)
fatal("dup() in/out/err failed");
/* should be pre-session */
init_local_fwd();
/* If requested, let ssh continue in the background. */
if (fork_after_authentication_flag)
if (daemon(1, 1) < 0)
fatal("daemon() failed: %.200s", strerror(errno));
window = 32*1024;
if (tty_flag) {
packetmax = window/8;
} else {
window *= 2;
packetmax = window/2;
}
/*XXX MAXPACK */
id = channel_new(
"session", SSH_CHANNEL_OPENING, in, out, err,
window, packetmax, CHAN_EXTENDED_WRITE, xstrdup("client-session"));
channel_open(id);
channel_register_callback(id, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, client_init, (void *)0);
return client_loop(tty_flag, tty_flag ? options.escape_char : -1, id);
}
/*
* Connect to the given ssh server using a proxy command.
*/
static int
ssh_proxy_connect(const char *host, u_short port, uid_t original_real_uid,
const char *proxy_command)
{
Buffer command;
const char *cp;
char *command_string;
int pin[2], pout[2];
pid_t pid;
char strport[NI_MAXSERV];
/* Convert the port number into a string. */
snprintf(strport, sizeof strport, "%hu", port);
/* Build the final command string in the buffer by making the
appropriate substitutions to the given proxy command. */
buffer_init(&command);
for (cp = proxy_command; *cp; cp++) {
if (cp[0] == '%' && cp[1] == '%') {
buffer_append(&command, "%", 1);
cp++;
continue;
}
if (cp[0] == '%' && cp[1] == 'h') {
buffer_append(&command, host, strlen(host));
cp++;
continue;
}
if (cp[0] == '%' && cp[1] == 'p') {
buffer_append(&command, strport, strlen(strport));
cp++;
continue;
}
buffer_append(&command, cp, 1);
}
buffer_append(&command, "\0", 1);
/* Get the final command string. */
command_string = buffer_ptr(&command);
/* Create pipes for communicating with the proxy. */
if (pipe(pin) < 0 || pipe(pout) < 0)
fatal("Could not create pipes to communicate with the proxy: %.100s",
strerror(errno));
debug("Executing proxy command: %.500s", command_string);
/* Fork and execute the proxy command. */
if ((pid = fork()) == 0) {
char *argv[10];
/* Child. Permanently give up superuser privileges. */
permanently_set_uid(original_real_uid);
/* Redirect stdin and stdout. */
close(pin[1]);
if (pin[0] != 0) {
if (dup2(pin[0], 0) < 0)
perror("dup2 stdin");
close(pin[0]);
}
close(pout[0]);
if (dup2(pout[1], 1) < 0)
perror("dup2 stdout");
/* Cannot be 1 because pin allocated two descriptors. */
close(pout[1]);
/* Stderr is left as it is so that error messages get
printed on the user's terminal. */
argv[0] = _PATH_BSHELL;
argv[1] = "-c";
argv[2] = command_string;
argv[3] = NULL;
/* Execute the proxy command. Note that we gave up any
extra privileges above. */
execv(_PATH_BSHELL, argv);
perror(_PATH_BSHELL);
exit(1);
}
/* Parent. */
if (pid < 0)
fatal("fork failed: %.100s", strerror(errno));
/* Close child side of the descriptors. */
close(pin[0]);
close(pout[1]);
/* Free the command name. */
buffer_free(&command);
/* Set the connection file descriptors. */
packet_set_connection(pout[0], pin[1]);
return 1;
}
/*
* Creates a (possibly privileged) socket for use as the ssh connection.
*/
static int
ssh_create_socket(uid_t original_real_uid, int privileged, int family)
{
int sock;
/*
* If we are running as root and want to connect to a privileged
* port, bind our own socket to a privileged port.
*/
if (privileged) {
int p = IPPORT_RESERVED - 1;
sock = rresvport_af(&p, family);
if (sock < 0)
error("rresvport: af=%d %.100s", family, strerror(errno));
else
debug("Allocated local port %d.", p);
} else {
/*
* Just create an ordinary socket on arbitrary port. We use
* the user's uid to create the socket.
*/
temporarily_use_uid(original_real_uid);
sock = socket(family, SOCK_STREAM, 0);
if (sock < 0)
error("socket: %.100s", strerror(errno));
restore_uid();
}
return sock;
}
/*
* Opens a TCP/IP connection to the remote server on the given host.
* The address of the remote host will be returned in hostaddr.
* If port is 0, the default port will be used. If anonymous is zero,
* a privileged port will be allocated to make the connection.
* This requires super-user privileges if anonymous is false.
* Connection_attempts specifies the maximum number of tries (one per
* second). If proxy_command is non-NULL, it specifies the command (with %h
* and %p substituted for host and port, respectively) to use to contact
* the daemon.
*/
static int
ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
u_short port, int connection_attempts,
int anonymous, uid_t original_real_uid,
const char *proxy_command)
{
int sock = -1, attempt;
struct servent *sp;
struct addrinfo hints, *ai, *aitop;
char ntop[NI_MAXHOST], strport[NI_MAXSERV];
int gaierr;
struct linger linger;
debug("ssh_connect: getuid %u geteuid %u anon %d",
(u_int) getuid(), (u_int) geteuid(), anonymous);
/* Get default port if port has not been set. */
if (port == 0) {
sp = getservbyname(SSH_SERVICE_NAME, "tcp");
if (sp)
port = ntohs(sp->s_port);
else
port = SSH_DEFAULT_PORT;
}
/* If a proxy command is given, connect using it. */
if (proxy_command != NULL)
return ssh_proxy_connect(host, port, original_real_uid, proxy_command);
/* No proxy command. */
memset(&hints, 0, sizeof(hints));
hints.ai_family = IPv4or6;
hints.ai_socktype = SOCK_STREAM;
snprintf(strport, sizeof strport, "%d", port);
if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
fatal("%s: %.100s: %s", __progname, host,
gai_strerror(gaierr));
/*
* Try to connect several times. On some machines, the first time
* will sometimes fail. In general socket code appears to behave
* quite magically on many machines.
*/
for (attempt = 0; attempt < connection_attempts; attempt++) {
if (attempt > 0)
debug("Trying again...");
/* Loop through addresses for this host, and try each one in
sequence until the connection succeeds. */
for (ai = aitop; ai; ai = ai->ai_next) {
if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
continue;
if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
ntop, sizeof(ntop), strport, sizeof(strport),
NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
error("ssh_connect: getnameinfo failed");
continue;
}
debug("Connecting to %.200s [%.100s] port %s.",
host, ntop, strport);
/* Create a socket for connecting. */
sock = ssh_create_socket(original_real_uid,
!anonymous && geteuid() == 0 && port < IPPORT_RESERVED,
ai->ai_family);
if (sock < 0)
continue;
/* Connect to the host. We use the user's uid in the
* hope that it will help with tcp_wrappers showing
* the remote uid as root.
*/
temporarily_use_uid(original_real_uid);
if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
/* Successful connection. */
memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
restore_uid();
break;
} else {
debug("connect: %.100s", strerror(errno));
restore_uid();
/*
* Close the failed socket; there appear to
* be some problems when reusing a socket for
* which connect() has already returned an
* error.
*/
shutdown(sock, SHUT_RDWR);
close(sock);
}
}
if (ai)
break; /* Successful connection. */
/* Sleep a moment before retrying. */
sleep(1);
}
freeaddrinfo(aitop);
/* Return failure if we didn't get a successful connection. */
if (attempt >= connection_attempts)
return 0;
debug("Connection established.");
/*
* Set socket options. We would like the socket to disappear as soon
* as it has been closed for whatever reason.
*/
/* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
linger.l_onoff = 1;
linger.l_linger = 5;
setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
/* Set the connection. */
packet_set_connection(sock, sock);
return 1;
}
/*
* Waits for the server identification string, and sends our own
* identification string.
*/
static void
ssh_exchange_identification()
{
char buf[256], remote_version[256]; /* must be same size! */
int remote_major, remote_minor, i, mismatch;
int connection_in = packet_get_connection_in();
int connection_out = packet_get_connection_out();
/* Read other side\'s version identification. */
for (;;) {
for (i = 0; i < sizeof(buf) - 1; i++) {
int len = atomicio(read, connection_in, &buf[i], 1);
if (len < 0)
fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
if (len != 1)
fatal("ssh_exchange_identification: Connection closed by remote host");
if (buf[i] == '\r') {
buf[i] = '\n';
buf[i + 1] = 0;
continue; /**XXX wait for \n */
}
if (buf[i] == '\n') {
buf[i + 1] = 0;
break;
}
}
buf[sizeof(buf) - 1] = 0;
if (strncmp(buf, "SSH-", 4) == 0)
break;
debug("ssh_exchange_identification: %s", buf);
}
server_version_string = xstrdup(buf);
/*
* Check that the versions match. In future this might accept
* several versions and set appropriate flags to handle them.
*/
if (sscanf(server_version_string, "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);
compat_datafellows(remote_version);
mismatch = 0;
switch(remote_major) {
case 1:
if (remote_minor == 99 &&
(options.protocol & SSH_PROTO_2) &&
!(options.protocol & SSH_PROTO_1_PREFERRED)) {
enable_compat20();
break;
}
if (!(options.protocol & SSH_PROTO_1)) {
mismatch = 1;
break;
}
if (remote_minor < 3) {
fatal("Remote machine has too old SSH software version.");
} else if (remote_minor == 3) {
/* We speak 1.3, too. */
enable_compat13();
if (options.forward_agent) {
log("Agent forwarding disabled for protocol 1.3");
options.forward_agent = 0;
}
}
break;
case 2:
if (options.protocol & SSH_PROTO_2) {
enable_compat20();
break;
}
/* FALLTHROUGH */
default:
mismatch = 1;
break;
}
if (mismatch)
fatal("Protocol major versions differ: %d vs. %d",
(options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
remote_major);
if (compat20)
packet_set_ssh2_format();
/* Send our own protocol version identification. */
snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
compat20 ? PROTOCOL_MINOR_2 : PROTOCOL_MINOR_1,
SSH_VERSION);
if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
fatal("write: %.100s", strerror(errno));
client_version_string = xstrdup(buf);
chop(client_version_string);
chop(server_version_string);
debug("Local version string %.100s", client_version_string);
}
static 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;
}
}
}
/*
* check whether the supplied host key is valid, return only if ok.
*/
static void
check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
const char *user_hostfile, const char *system_hostfile)
{
Key *file_key;
char *type = key_type(host_key);
char *ip = NULL;
char hostline[1000], *hostp;
HostStatus host_status;
HostStatus ip_status;
int local = 0, host_ip_differ = 0;
int salen;
char ntop[NI_MAXHOST];
/*
* 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 (local) {
debug("Forcing accepting of host key for loopback/localhost.");
return;
}
/*
* Turn off check_host_ip for proxy connects, since
* we don't have the remote ip-address
*/
if (options.proxy_command != NULL && options.check_host_ip)
options.check_host_ip = 0;
if (options.check_host_ip) {
if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
NULL, 0, NI_NUMERICHOST) != 0)
fatal("check_host_key: getnameinfo failed");
ip = xstrdup(ntop);
}
/*
* 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_status = check_host_in_hostfile(user_hostfile, host, host_key, file_key);
if (host_status == HOST_NEW)
host_status = check_host_in_hostfile(system_hostfile, host, host_key, file_key);
/*
* 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)) {
Key *ip_key = key_new(host_key->type);
ip_status = check_host_in_hostfile(user_hostfile, ip, host_key, ip_key);
if (ip_status == HOST_NEW)
ip_status = check_host_in_hostfile(system_hostfile, ip, host_key, ip_key);
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);
if (options.check_host_ip) {
if (ip_status == HOST_NEW) {
if (!add_host_to_hostfile(user_hostfile, ip, host_key))
log("Failed to add the %s host key for IP address '%.30s' to the list of known hosts (%.30s).",
type, ip, user_hostfile);
else
log("Warning: Permanently added the %s host key for IP address '%.30s' to the list of known hosts.",
type, ip);
} else if (ip_status != HOST_OK)
log("Warning: the %s host key for '%.200s' differs from the key for the IP address '%.30s'",
type, host, ip);
}
break;
case HOST_NEW:
/* 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 %s host key is known for %.200s and you have requested strict checking.", type, host);
} else if (options.strict_host_key_checking == 2) {
/* The default */
char prompt[1024];
char *fp = key_fingerprint(host_key);
snprintf(prompt, sizeof(prompt),
"The authenticity of host '%.200s' can't be established.\n"
"%s key fingerprint is %s.\n"
"Are you sure you want to continue connecting (yes/no)? ",
host, type, fp);
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);
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");
}
/* The host key has changed. */
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("Please contact your system administrator.");
error("Add correct host key in %.100s to get rid of this message.",
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("%s host key for %.200s has changed and you have requested strict checking.", type, 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);
}
/*
* 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.
*/
static void
ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost,
struct sockaddr *hostaddr, uid_t original_real_uid)
{
struct passwd *pw;
char *host, *cp;
char *server_user, *local_user;
/* 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 %u not found from user database.", original_real_uid);
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(server_user, host);
} else {
ssh_kex(host, hostaddr);
ssh_userauth(local_user, server_user, host, host_key_valid, own_host_key);
}
}
#endif /* SSH */
#endif /* CK_SSL */