X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/388e9f9f03409f358b986a0fe3fbef8d2fa38a2a..ef51930f93f523426b6c383a1802061fbede93be:/auth1.c diff --git a/auth1.c b/auth1.c index 8f2c5a80..676c8a66 100644 --- a/auth1.c +++ b/auth1.c @@ -1,36 +1,39 @@ /* * Copyright (c) 1995 Tatu Ylonen , 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 1.2 2000/04/29 18:11:52 markus Exp $"); +RCSID("$OpenBSD: auth1.c,v 1.43 2002/09/09 06:48:06 itojun 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" - -#ifdef HAVE_OSF_SIA -# include -# include -#endif +#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]; @@ -43,13 +46,12 @@ get_authname(int type) 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); @@ -57,171 +59,120 @@ get_authname(int 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 - loginfailed(user,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; -#ifdef HAVE_OSF_SIA - extern int saved_argc; - extern char **saved_argv; -#endif /* HAVE_OSF_SIA */ /* 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, reply; + tkt.length = dlen; + tkt.data = kdata; + + if (PRIVSEP(auth_krb5(authctxt, &tkt, + &client_user, &reply))) { + authenticated = 1; + snprintf(info, sizeof(info), + " tktuser %.100s", + client_user); + + /* Send response to client */ + packet_start( + SSH_SMSG_AUTH_KERBEROS_RESPONSE); + packet_put_string((char *) + reply.data, reply.length); + packet_send(); + packet_write_wait(); + + if (reply.length) + xfree(reply.data); + } +#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) { @@ -235,13 +186,12 @@ do_authloop(struct passwd * pw) * 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: @@ -257,26 +207,22 @@ do_authloop(struct passwd * pw) 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)) - log("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: @@ -285,9 +231,10 @@ do_authloop(struct passwd * pw) 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; @@ -303,41 +250,24 @@ do_authloop(struct passwd * pw) * 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); -#elif defined(HAVE_OSF_SIA) - /* Do SIA auth with password */ - if (sia_validate_user(NULL, saved_argc, saved_argv, - get_canonical_hostname(), pw->pw_name, NULL, 0, - NULL, password) == SIASUCCESS) { - authenticated = 1; - } -#else /* !USE_PAM && !HAVE_OSF_SIA */ /* 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; @@ -346,21 +276,15 @@ do_authloop(struct passwd * pw) 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: /* @@ -370,66 +294,60 @@ do_authloop(struct passwd * pw) 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; +#endif + if (!authctxt->valid && authenticated) + fatal("INTERNAL ERROR: authenticated invalid user %s", + authctxt->user); + +#ifdef _UNICOS + if (type == SSH_CMSG_AUTH_PASSWORD && !authenticated) + cray_login_failure(authctxt->user, IA_UDBERR); + if (authenticated && cray_access_denied(authctxt->user)) { + authenticated = 0; + fatal("Access denied for user %s.",authctxt->user); } -#else /* USE_PAM */ - if (authenticated) { - return; +#endif /* _UNICOS */ + +#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 (!use_privsep && + authenticated && authctxt->pw->pw_uid == 0 && + !auth_root_allowed(get_authname(type))) + authenticated = 0; +#endif +#ifdef USE_PAM + if (!use_privsep && 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) { -#ifdef WITH_AIXAUTHENTICATE - loginfailed(pw->pw_name,get_canonical_hostname(),"ssh"); -#endif /* WITH_AIXAUTHENTICATE */ - packet_disconnect(AUTH_FAIL_MSG, pw->pw_name); + if (authenticated) + return; + + if (authctxt->failures++ > AUTH_FAIL_MAX) { + 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(); @@ -440,97 +358,70 @@ do_authloop(struct passwd * pw) * 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 - extern char *aixloginmsg; -#endif /* WITH_AIXAUTHENTICATE */ + Authctxt *authctxt; + u_int ulen; + char *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); - - setproctitle("%s", user); - -#ifdef AFS - /* If machine has AFS, set process authentication group. */ - if (k_hasafs()) { - k_setpag(); - k_unlog(); + packet_check_eom(); + + if ((style = strchr(user, ':')) != NULL) + *style++ = '\0'; + +#ifdef KRB5 + /* XXX - SSH.com Kerberos v5 braindeath. */ + if ((datafellows & SSH_BUG_K5USER) && + options.kerberos_authentication) { + char *p; + if ((p = strchr(user, '@')) != NULL) + *p = '\0'; } -#endif /* AFS */ +#endif + + 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); + PRIVSEP(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, "")) { -#elif defined(HAVE_OSF_SIA) - (sia_validate_user(NULL, saved_argc, saved_argv, - get_canonical_hostname(), pw->pw_name, NULL, 0, NULL, - "") == SIASUCCESS)) { -#else /* !HAVE_OSF_SIA && !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 - /* We don't have a pty yet, so just label the line as "ssh" */ - if (loginsuccess(user,get_canonical_hostname(),"ssh",&aixloginmsg) < 0) - aixloginmsg = NULL; -#endif /* WITH_AIXAUTHENTICATE */ packet_start(SSH_SMSG_SUCCESS); packet_send(); packet_write_wait(); - /* Perform session preparation. */ - do_authenticated(pw); + return (authctxt); }