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freebsd-dev/crypto/openssh/sshconnect.c
Brian Feldman a61d605eda MFS: Don't use the canonical hostname here, too.
2001-02-04 20:16:14 +00:00

946 lines
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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_KRB5);
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_KRB5_FAILURE */
debug("Kerberos V5 authentication failed.");
ret = 0;
break;
case SSH_SMSG_AUTH_KRB5_RESPONSE:
/* SSH_SMSG_AUTH_KRB5_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_KRB5_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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