mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-24 11:29:10 +00:00
468 lines
12 KiB
C
468 lines
12 KiB
C
|
/*
|
||
|
* Copyright (c) 2000 Markus Friedl. All rights reserved.
|
||
|
*
|
||
|
* Redistribution and use in source and binary forms, with or without
|
||
|
* modification, are permitted provided that the following conditions
|
||
|
* are met:
|
||
|
* 1. Redistributions of source code must retain the above copyright
|
||
|
* notice, this list of conditions and the following disclaimer.
|
||
|
* 2. Redistributions in binary form must reproduce the above copyright
|
||
|
* notice, this list of conditions and the following disclaimer in the
|
||
|
* documentation and/or other materials provided with the distribution.
|
||
|
* 3. All advertising materials mentioning features or use of this software
|
||
|
* must display the following acknowledgement:
|
||
|
* This product includes software developed by Markus Friedl.
|
||
|
* 4. The name of the author may not be used to endorse or promote products
|
||
|
* derived from this software without specific prior written permission.
|
||
|
*
|
||
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
|
||
|
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
|
||
|
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
|
||
|
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
|
||
|
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
|
||
|
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||
|
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||
|
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||
|
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
|
||
|
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
||
|
*/
|
||
|
#include "includes.h"
|
||
|
RCSID("$OpenBSD: auth2.c,v 1.8 2000/05/08 17:42:24 markus Exp $");
|
||
|
|
||
|
#include <openssl/dsa.h>
|
||
|
#include <openssl/rsa.h>
|
||
|
#include <openssl/evp.h>
|
||
|
|
||
|
#include "xmalloc.h"
|
||
|
#include "rsa.h"
|
||
|
#include "ssh.h"
|
||
|
#include "pty.h"
|
||
|
#include "packet.h"
|
||
|
#include "buffer.h"
|
||
|
#include "cipher.h"
|
||
|
#include "servconf.h"
|
||
|
#include "compat.h"
|
||
|
#include "channels.h"
|
||
|
#include "bufaux.h"
|
||
|
#include "ssh2.h"
|
||
|
#include "auth.h"
|
||
|
#include "session.h"
|
||
|
#include "dispatch.h"
|
||
|
#include "auth.h"
|
||
|
#include "key.h"
|
||
|
#include "kex.h"
|
||
|
|
||
|
#include "dsa.h"
|
||
|
#include "uidswap.h"
|
||
|
|
||
|
/* import */
|
||
|
extern ServerOptions options;
|
||
|
extern unsigned char *session_id2;
|
||
|
extern int session_id2_len;
|
||
|
|
||
|
/* protocol */
|
||
|
|
||
|
void input_service_request(int type, int plen);
|
||
|
void input_userauth_request(int type, int plen);
|
||
|
void protocol_error(int type, int plen);
|
||
|
|
||
|
/* auth */
|
||
|
int ssh2_auth_none(struct passwd *pw);
|
||
|
int ssh2_auth_password(struct passwd *pw);
|
||
|
int ssh2_auth_pubkey(struct passwd *pw, unsigned char *raw, unsigned int rlen);
|
||
|
|
||
|
/* helper */
|
||
|
struct passwd* auth_set_user(char *u, char *s);
|
||
|
int user_dsa_key_allowed(struct passwd *pw, Key *key);
|
||
|
|
||
|
typedef struct Authctxt Authctxt;
|
||
|
struct Authctxt {
|
||
|
char *user;
|
||
|
char *service;
|
||
|
struct passwd pw;
|
||
|
int valid;
|
||
|
};
|
||
|
static Authctxt *authctxt = NULL;
|
||
|
static int userauth_success = 0;
|
||
|
|
||
|
/*
|
||
|
* loop until userauth_success == TRUE
|
||
|
*/
|
||
|
|
||
|
void
|
||
|
do_authentication2()
|
||
|
{
|
||
|
/* turn off skey/kerberos, not supported by SSH2 */
|
||
|
#ifdef SKEY
|
||
|
options.skey_authentication = 0;
|
||
|
#endif
|
||
|
#ifdef KRB4
|
||
|
options.kerberos_authentication = 0;
|
||
|
#endif
|
||
|
|
||
|
dispatch_init(&protocol_error);
|
||
|
dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
|
||
|
dispatch_run(DISPATCH_BLOCK, &userauth_success);
|
||
|
do_authenticated2();
|
||
|
}
|
||
|
|
||
|
void
|
||
|
protocol_error(int type, int plen)
|
||
|
{
|
||
|
log("auth: protocol error: type %d plen %d", type, plen);
|
||
|
packet_start(SSH2_MSG_UNIMPLEMENTED);
|
||
|
packet_put_int(0);
|
||
|
packet_send();
|
||
|
packet_write_wait();
|
||
|
}
|
||
|
|
||
|
void
|
||
|
input_service_request(int type, int plen)
|
||
|
{
|
||
|
unsigned int len;
|
||
|
int accept = 0;
|
||
|
char *service = packet_get_string(&len);
|
||
|
packet_done();
|
||
|
|
||
|
if (strcmp(service, "ssh-userauth") == 0) {
|
||
|
if (!userauth_success) {
|
||
|
accept = 1;
|
||
|
/* now we can handle user-auth requests */
|
||
|
dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
|
||
|
}
|
||
|
}
|
||
|
/* XXX all other service requests are denied */
|
||
|
|
||
|
if (accept) {
|
||
|
packet_start(SSH2_MSG_SERVICE_ACCEPT);
|
||
|
packet_put_cstring(service);
|
||
|
packet_send();
|
||
|
packet_write_wait();
|
||
|
} else {
|
||
|
debug("bad service request %s", service);
|
||
|
packet_disconnect("bad service request %s", service);
|
||
|
}
|
||
|
xfree(service);
|
||
|
}
|
||
|
|
||
|
void
|
||
|
input_userauth_request(int type, int plen)
|
||
|
{
|
||
|
static void (*authlog) (const char *fmt,...) = verbose;
|
||
|
static int attempt = 0;
|
||
|
unsigned int len, rlen;
|
||
|
int authenticated = 0;
|
||
|
char *raw, *user, *service, *method, *authmsg = NULL;
|
||
|
struct passwd *pw;
|
||
|
|
||
|
if (++attempt == AUTH_FAIL_MAX)
|
||
|
packet_disconnect("too many failed userauth_requests");
|
||
|
|
||
|
raw = packet_get_raw(&rlen);
|
||
|
if (plen != rlen)
|
||
|
fatal("plen != rlen");
|
||
|
user = packet_get_string(&len);
|
||
|
service = packet_get_string(&len);
|
||
|
method = packet_get_string(&len);
|
||
|
debug("userauth-request for user %s service %s method %s", user, service, method);
|
||
|
|
||
|
/* XXX we only allow the ssh-connection service */
|
||
|
pw = auth_set_user(user, service);
|
||
|
if (pw && strcmp(service, "ssh-connection")==0) {
|
||
|
if (strcmp(method, "none") == 0) {
|
||
|
authenticated = ssh2_auth_none(pw);
|
||
|
} else if (strcmp(method, "password") == 0) {
|
||
|
authenticated = ssh2_auth_password(pw);
|
||
|
} else if (strcmp(method, "publickey") == 0) {
|
||
|
authenticated = ssh2_auth_pubkey(pw, raw, rlen);
|
||
|
}
|
||
|
}
|
||
|
if (authenticated && pw && pw->pw_uid == 0 && !options.permit_root_login) {
|
||
|
authenticated = 0;
|
||
|
log("ROOT LOGIN REFUSED FROM %.200s",
|
||
|
get_canonical_hostname());
|
||
|
}
|
||
|
|
||
|
/* Raise logging level */
|
||
|
if (authenticated == 1 ||
|
||
|
attempt == AUTH_FAIL_LOG ||
|
||
|
strcmp(method, "password") == 0)
|
||
|
authlog = log;
|
||
|
|
||
|
/* Log before sending the reply */
|
||
|
if (authenticated == 1) {
|
||
|
authmsg = "Accepted";
|
||
|
} else if (authenticated == 0) {
|
||
|
authmsg = "Failed";
|
||
|
} else {
|
||
|
authmsg = "Postponed";
|
||
|
}
|
||
|
authlog("%s %s for %.200s from %.200s port %d ssh2",
|
||
|
authmsg,
|
||
|
method,
|
||
|
pw && pw->pw_uid == 0 ? "ROOT" : user,
|
||
|
get_remote_ipaddr(),
|
||
|
get_remote_port());
|
||
|
|
||
|
/* XXX todo: check if multiple auth methods are needed */
|
||
|
if (authenticated == 1) {
|
||
|
/* turn off userauth */
|
||
|
dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &protocol_error);
|
||
|
packet_start(SSH2_MSG_USERAUTH_SUCCESS);
|
||
|
packet_send();
|
||
|
packet_write_wait();
|
||
|
/* now we can break out */
|
||
|
userauth_success = 1;
|
||
|
} else if (authenticated == 0) {
|
||
|
packet_start(SSH2_MSG_USERAUTH_FAILURE);
|
||
|
packet_put_cstring("publickey,password"); /* XXX dynamic */
|
||
|
packet_put_char(0); /* XXX partial success, unused */
|
||
|
packet_send();
|
||
|
packet_write_wait();
|
||
|
}
|
||
|
|
||
|
xfree(service);
|
||
|
xfree(user);
|
||
|
xfree(method);
|
||
|
}
|
||
|
|
||
|
int
|
||
|
ssh2_auth_none(struct passwd *pw)
|
||
|
{
|
||
|
packet_done();
|
||
|
return auth_password(pw, "");
|
||
|
}
|
||
|
int
|
||
|
ssh2_auth_password(struct passwd *pw)
|
||
|
{
|
||
|
char *password;
|
||
|
int authenticated = 0;
|
||
|
int change;
|
||
|
unsigned int len;
|
||
|
change = packet_get_char();
|
||
|
if (change)
|
||
|
log("password change not supported");
|
||
|
password = packet_get_string(&len);
|
||
|
packet_done();
|
||
|
if (options.password_authentication &&
|
||
|
auth_password(pw, password) == 1)
|
||
|
authenticated = 1;
|
||
|
memset(password, 0, len);
|
||
|
xfree(password);
|
||
|
return authenticated;
|
||
|
}
|
||
|
int
|
||
|
ssh2_auth_pubkey(struct passwd *pw, unsigned char *raw, unsigned int rlen)
|
||
|
{
|
||
|
Buffer b;
|
||
|
Key *key;
|
||
|
char *pkalg, *pkblob, *sig;
|
||
|
unsigned int alen, blen, slen;
|
||
|
int have_sig;
|
||
|
int authenticated = 0;
|
||
|
|
||
|
if (options.dsa_authentication == 0) {
|
||
|
debug("pubkey auth disabled");
|
||
|
return 0;
|
||
|
}
|
||
|
if (datafellows & SSH_BUG_PUBKEYAUTH) {
|
||
|
log("bug compatibility with ssh-2.0.13 pubkey not implemented");
|
||
|
return 0;
|
||
|
}
|
||
|
have_sig = packet_get_char();
|
||
|
pkalg = packet_get_string(&alen);
|
||
|
if (strcmp(pkalg, KEX_DSS) != 0) {
|
||
|
xfree(pkalg);
|
||
|
log("bad pkalg %s", pkalg); /*XXX*/
|
||
|
return 0;
|
||
|
}
|
||
|
pkblob = packet_get_string(&blen);
|
||
|
key = dsa_key_from_blob(pkblob, blen);
|
||
|
if (key != NULL) {
|
||
|
if (have_sig) {
|
||
|
sig = packet_get_string(&slen);
|
||
|
packet_done();
|
||
|
buffer_init(&b);
|
||
|
buffer_append(&b, session_id2, session_id2_len);
|
||
|
buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
|
||
|
if (slen + 4 > rlen)
|
||
|
fatal("bad rlen/slen");
|
||
|
buffer_append(&b, raw, rlen - slen - 4);
|
||
|
#ifdef DEBUG_DSS
|
||
|
buffer_dump(&b);
|
||
|
#endif
|
||
|
/* test for correct signature */
|
||
|
if (user_dsa_key_allowed(pw, key) &&
|
||
|
dsa_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1)
|
||
|
authenticated = 1;
|
||
|
buffer_clear(&b);
|
||
|
xfree(sig);
|
||
|
} else {
|
||
|
packet_done();
|
||
|
debug("test key...");
|
||
|
/* test whether pkalg/pkblob are acceptable */
|
||
|
/* XXX fake reply and always send PK_OK ? */
|
||
|
/*
|
||
|
* XXX this allows testing whether a user is allowed
|
||
|
* to login: if you happen to have a valid pubkey this
|
||
|
* message is sent. the message is NEVER sent at all
|
||
|
* if a user is not allowed to login. is this an
|
||
|
* issue? -markus
|
||
|
*/
|
||
|
if (user_dsa_key_allowed(pw, key)) {
|
||
|
packet_start(SSH2_MSG_USERAUTH_PK_OK);
|
||
|
packet_put_string(pkalg, alen);
|
||
|
packet_put_string(pkblob, blen);
|
||
|
packet_send();
|
||
|
packet_write_wait();
|
||
|
authenticated = -1;
|
||
|
}
|
||
|
}
|
||
|
key_free(key);
|
||
|
}
|
||
|
xfree(pkalg);
|
||
|
xfree(pkblob);
|
||
|
return authenticated;
|
||
|
}
|
||
|
|
||
|
/* set and get current user */
|
||
|
|
||
|
struct passwd*
|
||
|
auth_get_user(void)
|
||
|
{
|
||
|
return (authctxt != NULL && authctxt->valid) ? &authctxt->pw : NULL;
|
||
|
}
|
||
|
|
||
|
struct passwd*
|
||
|
auth_set_user(char *u, char *s)
|
||
|
{
|
||
|
struct passwd *pw, *copy;
|
||
|
|
||
|
if (authctxt == NULL) {
|
||
|
authctxt = xmalloc(sizeof(*authctxt));
|
||
|
authctxt->valid = 0;
|
||
|
authctxt->user = xstrdup(u);
|
||
|
authctxt->service = xstrdup(s);
|
||
|
setproctitle("%s", u);
|
||
|
pw = getpwnam(u);
|
||
|
if (!pw || !allowed_user(pw)) {
|
||
|
log("auth_set_user: illegal user %s", u);
|
||
|
return NULL;
|
||
|
}
|
||
|
copy = &authctxt->pw;
|
||
|
memset(copy, 0, sizeof(*copy));
|
||
|
copy->pw_name = xstrdup(pw->pw_name);
|
||
|
copy->pw_passwd = xstrdup(pw->pw_passwd);
|
||
|
copy->pw_uid = pw->pw_uid;
|
||
|
copy->pw_gid = pw->pw_gid;
|
||
|
copy->pw_dir = xstrdup(pw->pw_dir);
|
||
|
copy->pw_shell = xstrdup(pw->pw_shell);
|
||
|
authctxt->valid = 1;
|
||
|
} else {
|
||
|
if (strcmp(u, authctxt->user) != 0 ||
|
||
|
strcmp(s, authctxt->service) != 0) {
|
||
|
log("auth_set_user: missmatch: (%s,%s)!=(%s,%s)",
|
||
|
u, s, authctxt->user, authctxt->service);
|
||
|
return NULL;
|
||
|
}
|
||
|
}
|
||
|
return auth_get_user();
|
||
|
}
|
||
|
|
||
|
/* return 1 if user allows given key */
|
||
|
int
|
||
|
user_dsa_key_allowed(struct passwd *pw, Key *key)
|
||
|
{
|
||
|
char line[8192], file[1024];
|
||
|
int found_key = 0;
|
||
|
unsigned int bits = -1;
|
||
|
FILE *f;
|
||
|
unsigned long linenum = 0;
|
||
|
struct stat st;
|
||
|
Key *found;
|
||
|
|
||
|
/* Temporarily use the user's uid. */
|
||
|
temporarily_use_uid(pw->pw_uid);
|
||
|
|
||
|
/* The authorized keys. */
|
||
|
snprintf(file, sizeof file, "%.500s/%.100s", pw->pw_dir,
|
||
|
SSH_USER_PERMITTED_KEYS2);
|
||
|
|
||
|
/* Fail quietly if file does not exist */
|
||
|
if (stat(file, &st) < 0) {
|
||
|
/* Restore the privileged uid. */
|
||
|
restore_uid();
|
||
|
return 0;
|
||
|
}
|
||
|
/* Open the file containing the authorized keys. */
|
||
|
f = fopen(file, "r");
|
||
|
if (!f) {
|
||
|
/* Restore the privileged uid. */
|
||
|
restore_uid();
|
||
|
return 0;
|
||
|
}
|
||
|
if (options.strict_modes) {
|
||
|
int fail = 0;
|
||
|
char buf[1024];
|
||
|
/* Check open file in order to avoid open/stat races */
|
||
|
if (fstat(fileno(f), &st) < 0 ||
|
||
|
(st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
|
||
|
(st.st_mode & 022) != 0) {
|
||
|
snprintf(buf, sizeof buf, "DSA authentication refused for %.100s: "
|
||
|
"bad ownership or modes for '%s'.", pw->pw_name, file);
|
||
|
fail = 1;
|
||
|
} else {
|
||
|
/* Check path to SSH_USER_PERMITTED_KEYS */
|
||
|
int i;
|
||
|
static const char *check[] = {
|
||
|
"", SSH_USER_DIR, NULL
|
||
|
};
|
||
|
for (i = 0; check[i]; i++) {
|
||
|
snprintf(line, sizeof line, "%.500s/%.100s",
|
||
|
pw->pw_dir, check[i]);
|
||
|
if (stat(line, &st) < 0 ||
|
||
|
(st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
|
||
|
(st.st_mode & 022) != 0) {
|
||
|
snprintf(buf, sizeof buf,
|
||
|
"DSA authentication refused for %.100s: "
|
||
|
"bad ownership or modes for '%s'.",
|
||
|
pw->pw_name, line);
|
||
|
fail = 1;
|
||
|
break;
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
if (fail) {
|
||
|
log(buf);
|
||
|
fclose(f);
|
||
|
restore_uid();
|
||
|
return 0;
|
||
|
}
|
||
|
}
|
||
|
found_key = 0;
|
||
|
found = key_new(KEY_DSA);
|
||
|
|
||
|
while (fgets(line, sizeof(line), f)) {
|
||
|
char *cp;
|
||
|
linenum++;
|
||
|
/* Skip leading whitespace, empty and comment lines. */
|
||
|
for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
|
||
|
;
|
||
|
if (!*cp || *cp == '\n' || *cp == '#')
|
||
|
continue;
|
||
|
bits = key_read(found, &cp);
|
||
|
if (bits == 0)
|
||
|
continue;
|
||
|
if (key_equal(found, key)) {
|
||
|
found_key = 1;
|
||
|
debug("matching key found: file %s, line %ld",
|
||
|
file, linenum);
|
||
|
break;
|
||
|
}
|
||
|
}
|
||
|
restore_uid();
|
||
|
fclose(f);
|
||
|
key_free(found);
|
||
|
return found_key;
|
||
|
}
|