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freebsd-dev/crypto/openssh/sshconnect.c
assar ed5525fcec Add code for being compatible with ssh.com's krb5 authentication. 
It is done by using the same ssh messages for v4 and v5 authentication
(since the ssh.com does not now anything about v4) and looking at the
contents after unpacking it to see if it is v4 or v5.
Based on code from Björn Grönvall <bg@sics.se>

PR:		misc/20504
2001-03-04 02:22:04 +00:00

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26 KiB
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/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* Code to connect to a remote host, and to perform the client side of the
* login (authentication) dialog.
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*/
#include "includes.h"
RCSID("$OpenBSD: sshconnect.c,v 1.79 2000/09/17 15:52:51 markus Exp $");
RCSID("$FreeBSD$");
#include <openssl/bn.h>
#include <openssl/dsa.h>
#include <openssl/rsa.h>
#include "xmalloc.h"
#include "rsa.h"
#include "ssh.h"
#include "buffer.h"
#include "packet.h"
#include "uidswap.h"
#include "compat.h"
#include "readconf.h"
#include "key.h"
#include "sshconnect.h"
#include "hostfile.h"
char *client_version_string = NULL;
char *server_version_string = NULL;
extern Options options;
extern char *__progname;
/*
* Connect to the given ssh server using a proxy command.
*/
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] = "/bin/sh";
argv[1] = "-c";
argv[2] = command_string;
argv[3] = NULL;
/* Execute the proxy command. Note that we gave up any
extra privileges above. */
execv("/bin/sh", argv);
perror("/bin/sh");
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.
*/
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 canonical host name used to connect will be returned in *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.
*/
int
ssh_connect(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;
hints.ai_flags = AI_CANONNAME;
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.",
ai->ai_canonname, 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) {
#if 0
if (ai->ai_canonname != NULL)
*host = xstrdup(ai->ai_canonname);
#endif
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.
*/
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);
}
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;
else if (strcmp(buf, "no") == 0)
retval = 0;
else
fprintf(stderr, "Please type 'yes' or 'no'.\n");
if (retval != -1) {
if (f != stdin)
fclose(f);
return retval;
}
}
}
/*
* check whether the supplied host key is valid, return only if ok.
*/
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;
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;
break;
case AF_INET6:
local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
break;
default:
local = 0;
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, hostaddr->sa_len, 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);
}
#ifdef KRB5
int
try_krb5_authentication(krb5_context *context, krb5_auth_context *auth_context)
{
krb5_error_code problem;
const char *tkfile;
struct stat buf;
krb5_ccache ccache = NULL;
krb5_creds req_creds;
krb5_creds *new_creds = NULL;
const char *remotehost;
krb5_data ap;
int type, payload_len;
krb5_ap_rep_enc_part *reply = NULL;
int ret;
memset(&ap, 0, sizeof(ap));
problem = krb5_init_context(context);
if (problem) {
ret = 0;
goto out;
}
tkfile = krb5_cc_default_name(*context);
if (strncmp(tkfile, "FILE:", 5) == 0)
tkfile += 5;
if (stat(tkfile, &buf) == 0 && getuid() != buf.st_uid) {
debug("Kerberos V5: could not get default ccache (permission denied).");
ret = 0;
goto out;
}
problem = krb5_cc_default(*context, &ccache);
if (problem) {
ret = 0;
goto out;
}
memset(&req_creds, 0, sizeof(req_creds));
remotehost = get_canonical_hostname();
problem = krb5_sname_to_principal(*context, remotehost,
"host", KRB5_NT_SRV_HST,
&req_creds.server);
if (problem) {
ret = 0;
goto out;
}
problem = krb5_cc_get_principal(*context, ccache, &req_creds.client);
if (problem) {
ret = 0;
goto out;
}
/* creds.session.keytype=ETYPE_DES_CBC_CRC; */
problem = krb5_get_credentials(*context, 0, ccache, &req_creds, &new_creds);
if (problem) {
ret = 0;
goto out;
}
problem = krb5_auth_con_init(*context, auth_context);
if (problem) {
ret = 0;
goto out;
}
/* krb5_auth_con_setflags(ssh_context, auth_context,
KRB5_AUTH_CONTEXT_RET_TIME);
*/
problem = krb5_mk_req_extended(*context, auth_context,
AP_OPTS_MUTUAL_REQUIRED /*| AP_OPTS_USE_SUBKEY*/ ,
NULL, new_creds, &ap);
if (problem) {
ret = 0;
goto out;
}
packet_start(SSH_CMSG_AUTH_KERBEROS);
packet_put_string((char *) ap.data, ap.length);
packet_send();
packet_write_wait();
xfree(ap.data);
ap.length = 0;
type = packet_read(&payload_len);
switch (type) {
case SSH_SMSG_FAILURE:
/* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */
debug("Kerberos V5 authentication failed.");
ret = 0;
break;
case SSH_SMSG_AUTH_KERBEROS_RESPONSE:
/* SSH_SMSG_AUTH_KERBEROS_SUCCESS */
debug("Kerberos V5 authentication accepted.");
/* Get server's response. */
ap.data = packet_get_string((unsigned int *) &ap.length);
packet_integrity_check(payload_len, 4 + ap.length, type);
/* XXX je to dobre? */
problem = krb5_rd_rep(*context, *auth_context, &ap, &reply);
if (problem) {
ret = 0;
}
ret = 1;
break;
default:
packet_disconnect("Protocol error on Kerberos V5 response: %d", type);
ret = 0;
break;
}
out:
if (req_creds.server != NULL)
krb5_free_principal(*context, req_creds.server);
if (req_creds.client != NULL)
krb5_free_principal(*context, req_creds.client);
if (new_creds != NULL)
krb5_free_creds(*context, new_creds);
if (ccache != NULL)
krb5_cc_close(*context, ccache);
if (reply != NULL)
krb5_free_ap_rep_enc_part(*context, reply);
if (ap.length > 0)
krb5_data_free(&ap);
return ret;
}
void
send_krb5_tgt(krb5_context context, krb5_auth_context auth_context)
{
int fd;
int type, payload_len;
krb5_error_code problem;
krb5_data outbuf;
krb5_ccache ccache = NULL;
krb5_creds creds;
krb5_kdc_flags flags;
const char* remotehost = get_canonical_hostname();
memset(&creds, 0, sizeof(creds));
memset(&outbuf, 0, sizeof(outbuf));
fd = packet_get_connection_in();
problem = krb5_auth_con_setaddrs_from_fd(context, auth_context, &fd);
if (problem) {
goto out;
}
#if 0
tkfile = krb5_cc_default_name(context);
if (strncmp(tkfile, "FILE:", 5) == 0)
tkfile += 5;
if (stat(tkfile, &buf) == 0 && getuid() != buf.st_uid) {
debug("Kerberos V5: could not get default ccache (permission denied).");
goto out;
}
#endif
problem = krb5_cc_default(context, &ccache);
if (problem) {
goto out;
}
problem = krb5_cc_get_principal(context, ccache, &creds.client);
if (problem) {
goto out;
}
problem = krb5_build_principal(context, &creds.server,
strlen(creds.client->realm),
creds.client->realm,
"krbtgt",
creds.client->realm,
NULL);
if (problem) {
goto out;
}
creds.times.endtime = 0;
flags.i = 0;
flags.b.forwarded = 1;
flags.b.forwardable = krb5_config_get_bool(context, NULL,
"libdefaults", "forwardable", NULL);
problem = krb5_get_forwarded_creds (context,
auth_context,
ccache,
flags.i,
remotehost,
&creds,
&outbuf);
if (problem) {
goto out;
}
packet_start(SSH_CMSG_HAVE_KERBEROS_TGT);
packet_put_string((char *)outbuf.data, outbuf.length);
packet_send();
packet_write_wait();
type = packet_read(&payload_len);
switch (type) {
case SSH_SMSG_SUCCESS:
break;
case SSH_SMSG_FAILURE:
break;
default:
break;
}
out:
if (creds.client)
krb5_free_principal(context, creds.client);
if (creds.server)
krb5_free_principal(context, creds.server);
if (ccache)
krb5_cc_close(context, ccache);
if (outbuf.data)
xfree(outbuf.data);
return;
}
#endif /* KRB5 */
/*
* Starts a dialog with the server, and authenticates the current user on the
* server. This does not need any extra privileges. The basic connection
* to the server must already have been established before this is called.
* If login fails, this function prints an error and never returns.
* This function does not require super-user privileges.
*/
void
ssh_login(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);
}
}
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