/*
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
+ *
+ * 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: auth1.c,v 1.1 2000/04/26 21:28:32 markus Exp $");
+RCSID("$OpenBSD: auth1.c,v 1.39 2002/03/19 14:27:39 markus Exp $");
#include "xmalloc.h"
#include "rsa.h"
-#include "ssh.h"
+#include "ssh1.h"
#include "packet.h"
#include "buffer.h"
-#include "cipher.h"
#include "mpaux.h"
+#include "log.h"
#include "servconf.h"
#include "compat.h"
#include "auth.h"
+#include "channels.h"
#include "session.h"
+#include "uidswap.h"
+#include "monitor_wrap.h"
/* import */
extern ServerOptions options;
-extern char *forced_command;
/*
* convert ssh auth msg type into description
*/
-char *
+static char *
get_authname(int type)
{
static char buf[1024];
return "rhosts-rsa";
case SSH_CMSG_AUTH_RHOSTS:
return "rhosts";
-#ifdef KRB4
+ case SSH_CMSG_AUTH_TIS:
+ case SSH_CMSG_AUTH_TIS_RESPONSE:
+ return "challenge-response";
+#if defined(KRB4) || defined(KRB5)
case SSH_CMSG_AUTH_KERBEROS:
return "kerberos";
-#endif
-#ifdef SKEY
- case SSH_CMSG_AUTH_TIS_RESPONSE:
- return "s/key";
#endif
}
snprintf(buf, sizeof buf, "bad-auth-msg-%d", type);
}
/*
- * The user does not exist or access is denied,
- * but fake indication that authentication is needed.
+ * read packets, try to authenticate the user and
+ * return only if authentication is successful
*/
-void
-do_fake_authloop1(char *user)
+static void
+do_authloop(Authctxt *authctxt)
{
- int attempt = 0;
-
- log("Faking authloop for illegal user %.200s from %.200s port %d",
- user,
- get_remote_ipaddr(),
- get_remote_port());
-
-#ifdef WITH_AIXAUTHENTICATE
- if (strncmp(get_authname(type),"password",
- strlen(get_authname(type))) == 0)
- loginfailed(pw->pw_name,get_canonical_hostname(),"ssh");
-#endif /* WITH_AIXAUTHENTICATE */
+ int authenticated = 0;
+ u_int bits;
+ Key *client_host_key;
+ BIGNUM *n;
+ char *client_user, *password;
+ char info[1024];
+ u_int dlen;
+ u_int ulen;
+ int type = 0;
+ struct passwd *pw = authctxt->pw;
- /* Indicate that authentication is needed. */
- packet_start(SSH_SMSG_FAILURE);
- packet_send();
- packet_write_wait();
+ debug("Attempting authentication for %s%.100s.",
+ authctxt->valid ? "" : "illegal user ", authctxt->user);
- /*
- * Keep reading packets, and always respond with a failure. This is
- * to avoid disclosing whether such a user really exists.
- */
- for (attempt = 1;; attempt++) {
- /* Read a packet. This will not return if the client disconnects. */
- int plen;
-#ifndef SKEY
- (void)packet_read(&plen);
-#else /* SKEY */
- int type = packet_read(&plen);
- unsigned int dlen;
- char *password, *skeyinfo;
- password = NULL;
- /* Try to send a fake s/key challenge. */
- if (options.skey_authentication == 1 &&
- (skeyinfo = skey_fake_keyinfo(user)) != NULL) {
- if (type == SSH_CMSG_AUTH_TIS) {
- packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
- packet_put_string(skeyinfo, strlen(skeyinfo));
- packet_send();
- packet_write_wait();
- continue;
- } else if (type == SSH_CMSG_AUTH_PASSWORD &&
- options.password_authentication &&
- (password = packet_get_string(&dlen)) != NULL &&
- dlen == 5 &&
- strncasecmp(password, "s/key", 5) == 0 ) {
- packet_send_debug(skeyinfo);
- }
- }
- if (password != NULL)
- xfree(password);
+ /* If the user has no password, accept authentication immediately. */
+ if (options.password_authentication &&
+#if defined(KRB4) || defined(KRB5)
+ (!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
#endif
- if (attempt > AUTH_FAIL_MAX)
- packet_disconnect(AUTH_FAIL_MSG, user);
-
- /*
- * Send failure. This should be indistinguishable from a
- * failed authentication.
- */
- packet_start(SSH_SMSG_FAILURE);
- packet_send();
- packet_write_wait();
+ PRIVSEP(auth_password(authctxt, ""))) {
+ auth_log(authctxt, 1, "without authentication", "");
+ return;
}
- /* NOTREACHED */
- abort();
-}
-
-/*
- * read packets and try to authenticate local user *pw.
- * return if authentication is successfull
- */
-void
-do_authloop(struct passwd * pw)
-{
- int attempt = 0;
- unsigned int bits;
- RSA *client_host_key;
- BIGNUM *n;
- char *client_user = NULL, *password = NULL;
- char user[1024];
- unsigned int dlen;
- int plen, nlen, elen;
- unsigned int ulen;
- int type = 0;
- void (*authlog) (const char *fmt,...) = verbose;
/* Indicate that authentication is needed. */
packet_start(SSH_SMSG_FAILURE);
packet_send();
packet_write_wait();
- for (attempt = 1;; attempt++) {
- int authenticated = 0;
- strlcpy(user, "", sizeof user);
+ client_user = NULL;
+
+ for (;;) {
+ /* default to fail */
+ authenticated = 0;
+
+ info[0] = '\0';
/* Get a packet from the client. */
- type = packet_read(&plen);
+ type = packet_read();
/* Process the packet. */
switch (type) {
-#ifdef AFS
- case SSH_CMSG_HAVE_KERBEROS_TGT:
- if (!options.kerberos_tgt_passing) {
- /* packet_get_all(); */
- verbose("Kerberos tgt passing disabled.");
- break;
- } else {
- /* Accept Kerberos tgt. */
- char *tgt = packet_get_string(&dlen);
- packet_integrity_check(plen, 4 + dlen, type);
- if (!auth_kerberos_tgt(pw, tgt))
- verbose("Kerberos tgt REFUSED for %s", pw->pw_name);
- xfree(tgt);
- }
- continue;
- case SSH_CMSG_HAVE_AFS_TOKEN:
- if (!options.afs_token_passing || !k_hasafs()) {
- /* packet_get_all(); */
- verbose("AFS token passing disabled.");
- break;
- } else {
- /* Accept AFS token. */
- char *token_string = packet_get_string(&dlen);
- packet_integrity_check(plen, 4 + dlen, type);
- if (!auth_afs_token(pw, token_string))
- verbose("AFS token REFUSED for %s", pw->pw_name);
- xfree(token_string);
- }
- continue;
-#endif /* AFS */
-#ifdef KRB4
+#if defined(KRB4) || defined(KRB5)
case SSH_CMSG_AUTH_KERBEROS:
if (!options.kerberos_authentication) {
- /* packet_get_all(); */
verbose("Kerberos authentication disabled.");
- break;
} else {
- /* Try Kerberos v4 authentication. */
- KTEXT_ST auth;
- char *tkt_user = NULL;
- char *kdata = packet_get_string((unsigned int *) &auth.length);
- packet_integrity_check(plen, 4 + auth.length, type);
-
- if (auth.length < MAX_KTXT_LEN)
- memcpy(auth.dat, kdata, auth.length);
- xfree(kdata);
-
- authenticated = auth_krb4(pw->pw_name, &auth, &tkt_user);
+ char *kdata = packet_get_string(&dlen);
+ packet_check_eom();
- if (authenticated) {
- snprintf(user, sizeof user, " tktuser %s", tkt_user);
- xfree(tkt_user);
+ if (kdata[0] == 4) { /* KRB_PROT_VERSION */
+#ifdef KRB4
+ KTEXT_ST tkt;
+
+ tkt.length = dlen;
+ if (tkt.length < MAX_KTXT_LEN)
+ memcpy(tkt.dat, kdata, tkt.length);
+
+ if (auth_krb4(authctxt, &tkt, &client_user)) {
+ authenticated = 1;
+ snprintf(info, sizeof(info),
+ " tktuser %.100s",
+ client_user);
+ }
+#endif /* KRB4 */
+ } else {
+#ifdef KRB5
+ krb5_data tkt;
+ tkt.length = dlen;
+ tkt.data = kdata;
+
+ if (auth_krb5(authctxt, &tkt, &client_user)) {
+ authenticated = 1;
+ snprintf(info, sizeof(info),
+ " tktuser %.100s",
+ client_user);
+ }
+#endif /* KRB5 */
}
+ xfree(kdata);
}
break;
-#endif /* KRB4 */
+#endif /* KRB4 || KRB5 */
+
+#if defined(AFS) || defined(KRB5)
+ /* XXX - punt on backward compatibility here. */
+ case SSH_CMSG_HAVE_KERBEROS_TGT:
+ packet_send_debug("Kerberos TGT passing disabled before authentication.");
+ break;
+#ifdef AFS
+ case SSH_CMSG_HAVE_AFS_TOKEN:
+ packet_send_debug("AFS token passing disabled before authentication.");
+ break;
+#endif /* AFS */
+#endif /* AFS || KRB5 */
case SSH_CMSG_AUTH_RHOSTS:
if (!options.rhosts_authentication) {
* IP-spoofing on a local network.)
*/
client_user = packet_get_string(&ulen);
- packet_integrity_check(plen, 4 + ulen, type);
+ packet_check_eom();
- /* Try to authenticate using /etc/hosts.equiv and
- .rhosts. */
+ /* Try to authenticate using /etc/hosts.equiv and .rhosts. */
authenticated = auth_rhosts(pw, client_user);
- snprintf(user, sizeof user, " ruser %s", client_user);
+ snprintf(info, sizeof info, " ruser %.100s", client_user);
break;
case SSH_CMSG_AUTH_RHOSTS_RSA:
client_user = packet_get_string(&ulen);
/* Get the client host key. */
- client_host_key = RSA_new();
- if (client_host_key == NULL)
- fatal("RSA_new failed");
- client_host_key->e = BN_new();
- client_host_key->n = BN_new();
- if (client_host_key->e == NULL || client_host_key->n == NULL)
- fatal("BN_new failed");
+ client_host_key = key_new(KEY_RSA1);
bits = packet_get_int();
- packet_get_bignum(client_host_key->e, &elen);
- packet_get_bignum(client_host_key->n, &nlen);
+ packet_get_bignum(client_host_key->rsa->e);
+ packet_get_bignum(client_host_key->rsa->n);
- if (bits != BN_num_bits(client_host_key->n))
- error("Warning: keysize mismatch for client_host_key: "
- "actual %d, announced %d", BN_num_bits(client_host_key->n), bits);
- packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type);
+ if (bits != BN_num_bits(client_host_key->rsa->n))
+ verbose("Warning: keysize mismatch for client_host_key: "
+ "actual %d, announced %d",
+ BN_num_bits(client_host_key->rsa->n), bits);
+ packet_check_eom();
- authenticated = auth_rhosts_rsa(pw, client_user, client_host_key);
- RSA_free(client_host_key);
+ authenticated = auth_rhosts_rsa(pw, client_user,
+ client_host_key);
+ key_free(client_host_key);
- snprintf(user, sizeof user, " ruser %s", client_user);
+ snprintf(info, sizeof info, " ruser %.100s", client_user);
break;
case SSH_CMSG_AUTH_RSA:
break;
}
/* RSA authentication requested. */
- n = BN_new();
- packet_get_bignum(n, &nlen);
- packet_integrity_check(plen, nlen, type);
+ if ((n = BN_new()) == NULL)
+ fatal("do_authloop: BN_new failed");
+ packet_get_bignum(n);
+ packet_check_eom();
authenticated = auth_rsa(pw, n);
BN_clear_free(n);
break;
* not visible to an outside observer.
*/
password = packet_get_string(&dlen);
- packet_integrity_check(plen, 4 + dlen, type);
+ packet_check_eom();
-#ifdef USE_PAM
- /* Do PAM auth with password */
- authenticated = auth_pam_password(pw, password);
-#else /* USE_PAM */
/* Try authentication with the password. */
- authenticated = auth_password(pw, password);
-#endif /* USE_PAM */
+ authenticated = PRIVSEP(auth_password(authctxt, password));
memset(password, 0, strlen(password));
xfree(password);
break;
-#ifdef SKEY
case SSH_CMSG_AUTH_TIS:
debug("rcvd SSH_CMSG_AUTH_TIS");
- if (options.skey_authentication == 1) {
- char *skeyinfo = skey_keyinfo(pw->pw_name);
- if (skeyinfo == NULL) {
- debug("generating fake skeyinfo for %.100s.", pw->pw_name);
- skeyinfo = skey_fake_keyinfo(pw->pw_name);
- }
- if (skeyinfo != NULL) {
- /* we send our s/key- in tis-challenge messages */
- debug("sending challenge '%s'", skeyinfo);
+ if (options.challenge_response_authentication == 1) {
+ char *challenge = get_challenge(authctxt);
+ if (challenge != NULL) {
+ debug("sending challenge '%s'", challenge);
packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
- packet_put_string(skeyinfo, strlen(skeyinfo));
+ packet_put_cstring(challenge);
+ xfree(challenge);
packet_send();
packet_write_wait();
continue;
break;
case SSH_CMSG_AUTH_TIS_RESPONSE:
debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE");
- if (options.skey_authentication == 1) {
+ if (options.challenge_response_authentication == 1) {
char *response = packet_get_string(&dlen);
- debug("skey response == '%s'", response);
- packet_integrity_check(plen, 4 + dlen, type);
- authenticated = (skey_haskey(pw->pw_name) == 0 &&
- skey_passcheck(pw->pw_name, response) != -1);
+ debug("got response '%s'", response);
+ packet_check_eom();
+ authenticated = verify_response(authctxt, response);
+ memset(response, 'r', dlen);
xfree(response);
}
break;
-#else
- case SSH_CMSG_AUTH_TIS:
- /* TIS Authentication is unsupported */
- log("TIS authentication unsupported.");
- break;
-#endif
default:
/*
log("Unknown message during authentication: type %d", type);
break;
}
-
- /*
- * Check if the user is logging in as root and root logins
- * are disallowed.
- * Note that root login is allowed for forced commands.
- */
- if (authenticated && pw->pw_uid == 0 && !options.permit_root_login) {
- if (forced_command) {
- log("Root login accepted for forced command.");
- } else {
- authenticated = 0;
- log("ROOT LOGIN REFUSED FROM %.200s",
- get_canonical_hostname());
- }
+#ifdef BSD_AUTH
+ if (authctxt->as) {
+ auth_close(authctxt->as);
+ authctxt->as = NULL;
}
-
- /* Raise logging level */
- if (authenticated ||
- attempt == AUTH_FAIL_LOG ||
- type == SSH_CMSG_AUTH_PASSWORD)
- authlog = log;
-
- authlog("%s %s for %.200s from %.200s port %d%s",
- authenticated ? "Accepted" : "Failed",
- get_authname(type),
- pw->pw_uid == 0 ? "ROOT" : pw->pw_name,
- get_remote_ipaddr(),
- get_remote_port(),
- user);
-
-#ifdef USE_PAM
- if (authenticated) {
- if (!do_pam_account(pw->pw_name, client_user)) {
- if (client_user != NULL) {
- xfree(client_user);
- client_user = NULL;
- }
- do_fake_authloop1(pw->pw_name);
- }
- return;
- }
-#else /* USE_PAM */
- if (authenticated) {
- return;
+#endif
+ if (!authctxt->valid && authenticated)
+ fatal("INTERNAL ERROR: authenticated invalid user %s",
+ authctxt->user);
+
+#ifdef HAVE_CYGWIN
+ if (authenticated &&
+ !check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD, pw)) {
+ packet_disconnect("Authentication rejected for uid %d.",
+ pw == NULL ? -1 : pw->pw_uid);
+ authenticated = 0;
}
-#endif /* USE_PAM */
+#else
+ /* Special handling for root */
+ if (authenticated && authctxt->pw->pw_uid == 0 &&
+ !auth_root_allowed(get_authname(type)))
+ authenticated = 0;
+#endif
+#ifdef USE_PAM
+ if (authenticated && !do_pam_account(pw->pw_name, client_user))
+ authenticated = 0;
+#endif
+
+ /* Log before sending the reply */
+ auth_log(authctxt, authenticated, get_authname(type), info);
if (client_user != NULL) {
xfree(client_user);
client_user = NULL;
}
- if (attempt > AUTH_FAIL_MAX)
- packet_disconnect(AUTH_FAIL_MSG, pw->pw_name);
+ if (authenticated)
+ return;
+
+ if (authctxt->failures++ > AUTH_FAIL_MAX) {
+#ifdef WITH_AIXAUTHENTICATE
+ loginfailed(authctxt->user,
+ get_canonical_hostname(options.verify_reverse_mapping),
+ "ssh");
+#endif /* WITH_AIXAUTHENTICATE */
+ packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
+ }
- /* Send a message indicating that the authentication attempt failed. */
packet_start(SSH_SMSG_FAILURE);
packet_send();
packet_write_wait();
* Performs authentication of an incoming connection. Session key has already
* been exchanged and encryption is enabled.
*/
-void
-do_authentication()
+Authctxt *
+do_authentication(void)
{
- struct passwd *pw, pwcopy;
- int plen;
- unsigned int ulen;
- char *user;
-#ifdef WITH_AIXAUTHENTICATE
- char *loginmsg;
-#endif /* WITH_AIXAUTHENTICATE */
+ Authctxt *authctxt;
+ u_int ulen;
+ char *p, *user, *style = NULL;
/* Get the name of the user that we wish to log in as. */
- packet_read_expect(&plen, SSH_CMSG_USER);
+ packet_read_expect(SSH_CMSG_USER);
/* Get the user name. */
user = packet_get_string(&ulen);
- packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER);
+ packet_check_eom();
- setproctitle("%s", user);
+ if ((style = strchr(user, ':')) != NULL)
+ *style++ = '\0';
-#ifdef AFS
- /* If machine has AFS, set process authentication group. */
- if (k_hasafs()) {
- k_setpag();
- k_unlog();
- }
-#endif /* AFS */
+ /* XXX - SSH.com Kerberos v5 braindeath. */
+ if ((p = strchr(user, '@')) != NULL)
+ *p = '\0';
+
+ authctxt = authctxt_new();
+ authctxt->user = user;
+ authctxt->style = style;
/* Verify that the user is a valid user. */
- pw = getpwnam(user);
- if (!pw || !allowed_user(pw))
- do_fake_authloop1(user);
- xfree(user);
-
- /* 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;
- pwcopy.pw_dir = xstrdup(pw->pw_dir);
- pwcopy.pw_shell = xstrdup(pw->pw_shell);
- pw = &pwcopy;
+ if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL)
+ authctxt->valid = 1;
+ else
+ debug("do_authentication: illegal user %s", user);
+
+ setproctitle("%s%s", authctxt->pw ? user : "unknown",
+ use_privsep ? " [net]" : "");
#ifdef USE_PAM
- start_pam(pw);
+ start_pam(authctxt->pw == NULL ? "NOUSER" : user);
#endif
/*
* If we are not running as root, the user must have the same uid as
- * the server.
+ * the server. (Unless you are running Windows)
*/
- if (getuid() != 0 && pw->pw_uid != getuid())
+#ifndef HAVE_CYGWIN
+ if (!use_privsep && getuid() != 0 && authctxt->pw &&
+ authctxt->pw->pw_uid != getuid())
packet_disconnect("Cannot change user when server not running as root.");
+#endif
- debug("Attempting authentication for %.100s.", pw->pw_name);
-
- /* If the user has no password, accept authentication immediately. */
- if (options.password_authentication &&
-#ifdef KRB4
- (!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
-#endif /* KRB4 */
-#ifdef USE_PAM
- auth_pam_password(pw, "")) {
-#else /* USE_PAM */
- auth_password(pw, "")) {
-#endif /* USE_PAM */
- /* Authentication with empty password succeeded. */
- log("Login for user %s from %.100s, accepted without authentication.",
- pw->pw_name, get_remote_ipaddr());
- } else {
- /* Loop until the user has been authenticated or the
- connection is closed, do_authloop() returns only if
- authentication is successfull */
- do_authloop(pw);
- }
+ /*
+ * Loop until the user has been authenticated or the connection is
+ * closed, do_authloop() returns only if authentication is successful
+ */
+ do_authloop(authctxt);
/* The user has been authenticated and accepted. */
-#ifdef WITH_AIXAUTHENTICATE
- loginsuccess(user,get_canonical_hostname(),"ssh",&loginmsg);
-#endif /* WITH_AIXAUTHENTICATE */
packet_start(SSH_SMSG_SUCCESS);
packet_send();
packet_write_wait();
- /* Perform session preparation. */
- do_authenticated(pw);
+ return (authctxt);
}
andersk / openssh.git / blobdiff