| /* |
| * 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 1.11 2001/01/18 16:59:59 markus Exp $"); |
| |
| #ifdef HAVE_OSF_SIA |
| # include <sia.h> |
| # include <siad.h> |
| #endif |
| |
| #include "xmalloc.h" |
| #include "rsa.h" |
| #include "ssh.h" |
| #include "packet.h" |
| #include "buffer.h" |
| #include "mpaux.h" |
| #include "servconf.h" |
| #include "compat.h" |
| #include "auth.h" |
| #include "session.h" |
| |
| /* import */ |
| extern ServerOptions options; |
| extern char *forced_command; |
| |
| #ifdef WITH_AIXAUTHENTICATE |
| extern char *aixloginmsg; |
| #endif /* WITH_AIXAUTHENTICATE */ |
| #ifdef HAVE_OSF_SIA |
| extern int saved_argc; |
| extern char **saved_argv; |
| #endif /* HAVE_OSF_SIA */ |
| |
| /* |
| * convert ssh auth msg type into description |
| */ |
| char * |
| get_authname(int type) |
| { |
| static char buf[1024]; |
| switch (type) { |
| case SSH_CMSG_AUTH_PASSWORD: |
| return "password"; |
| case SSH_CMSG_AUTH_RSA: |
| return "rsa"; |
| case SSH_CMSG_AUTH_RHOSTS_RSA: |
| return "rhosts-rsa"; |
| case SSH_CMSG_AUTH_RHOSTS: |
| return "rhosts"; |
| case SSH_CMSG_AUTH_TIS: |
| case SSH_CMSG_AUTH_TIS_RESPONSE: |
| return "challenge-response"; |
| #ifdef KRB4 |
| case SSH_CMSG_AUTH_KERBEROS: |
| return "kerberos"; |
| #endif |
| } |
| snprintf(buf, sizeof buf, "bad-auth-msg-%d", type); |
| return buf; |
| } |
| |
| /* |
| * read packets, try to authenticate the user and |
| * return only if authentication is successful |
| */ |
| void |
| do_authloop(Authctxt *authctxt) |
| { |
| int authenticated = 0; |
| u_int bits; |
| RSA *client_host_key; |
| BIGNUM *n; |
| char *client_user, *password; |
| char info[1024]; |
| u_int dlen; |
| int plen, nlen, elen; |
| u_int ulen; |
| int type = 0; |
| struct passwd *pw = authctxt->pw; |
| |
| debug("Attempting authentication for %s%.100s.", |
| authctxt->valid ? "" : "illegal user ", authctxt->user); |
| |
| /* If the user has no password, accept authentication immediately. */ |
| if (options.password_authentication && |
| #ifdef KRB4 |
| (!options.kerberos_authentication || options.kerberos_or_local_passwd) && |
| #endif |
| #ifdef USE_PAM |
| auth_pam_password(pw, password)) { |
| #else |
| auth_password(pw, "")) { |
| #endif |
| auth_log(authctxt, 1, "without authentication", ""); |
| return; |
| } |
| |
| /* Indicate that authentication is needed. */ |
| packet_start(SSH_SMSG_FAILURE); |
| packet_send(); |
| packet_write_wait(); |
| |
| client_user = NULL; |
| |
| for (;;) { |
| /* default to fail */ |
| authenticated = 0; |
| |
| info[0] = '\0'; |
| |
| /* Get a packet from the client. */ |
| type = packet_read(&plen); |
| |
| /* Process the packet. */ |
| switch (type) { |
| #ifdef AFS |
| case SSH_CMSG_HAVE_KERBEROS_TGT: |
| if (!options.kerberos_tgt_passing) { |
| 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 %.100s", authctxt->user); |
| xfree(tgt); |
| } |
| continue; |
| |
| case SSH_CMSG_HAVE_AFS_TOKEN: |
| if (!options.afs_token_passing || !k_hasafs()) { |
| 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 %.100s", authctxt->user); |
| xfree(token_string); |
| } |
| continue; |
| #endif /* AFS */ |
| #ifdef KRB4 |
| case SSH_CMSG_AUTH_KERBEROS: |
| if (!options.kerberos_authentication) { |
| verbose("Kerberos authentication disabled."); |
| break; |
| } else { |
| /* Try Kerberos v4 authentication. */ |
| KTEXT_ST auth; |
| char *tkt_user = NULL; |
| char *kdata = packet_get_string((u_int *) &auth.length); |
| packet_integrity_check(plen, 4 + auth.length, type); |
| |
| if (authctxt->valid) { |
| if (auth.length < MAX_KTXT_LEN) |
| memcpy(auth.dat, kdata, auth.length); |
| authenticated = auth_krb4(pw->pw_name, &auth, &tkt_user); |
| if (authenticated) { |
| snprintf(info, sizeof info, |
| " tktuser %.100s", tkt_user); |
| xfree(tkt_user); |
| } |
| } |
| xfree(kdata); |
| } |
| break; |
| #endif /* KRB4 */ |
| |
| case SSH_CMSG_AUTH_RHOSTS: |
| if (!options.rhosts_authentication) { |
| verbose("Rhosts authentication disabled."); |
| break; |
| } |
| /* |
| * Get client user name. Note that we just have to |
| * trust the client; this is one reason why rhosts |
| * authentication is insecure. (Another is |
| * IP-spoofing on a local network.) |
| */ |
| client_user = packet_get_string(&ulen); |
| packet_integrity_check(plen, 4 + ulen, type); |
| |
| /* Try to authenticate using /etc/hosts.equiv and .rhosts. */ |
| authenticated = auth_rhosts(pw, client_user); |
| |
| snprintf(info, sizeof info, " ruser %.100s", client_user); |
| break; |
| |
| case SSH_CMSG_AUTH_RHOSTS_RSA: |
| if (!options.rhosts_rsa_authentication) { |
| verbose("Rhosts with RSA authentication disabled."); |
| break; |
| } |
| /* |
| * Get client user name. Note that we just have to |
| * trust the client; root on the client machine can |
| * claim to be any user. |
| */ |
| 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"); |
| bits = packet_get_int(); |
| packet_get_bignum(client_host_key->e, &elen); |
| packet_get_bignum(client_host_key->n, &nlen); |
| |
| if (bits != BN_num_bits(client_host_key->n)) |
| verbose("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); |
| |
| authenticated = auth_rhosts_rsa(pw, client_user, client_host_key); |
| RSA_free(client_host_key); |
| |
| snprintf(info, sizeof info, " ruser %.100s", client_user); |
| break; |
| |
| case SSH_CMSG_AUTH_RSA: |
| if (!options.rsa_authentication) { |
| verbose("RSA authentication disabled."); |
| break; |
| } |
| /* RSA authentication requested. */ |
| n = BN_new(); |
| packet_get_bignum(n, &nlen); |
| packet_integrity_check(plen, nlen, type); |
| authenticated = auth_rsa(pw, n); |
| BN_clear_free(n); |
| break; |
| |
| case SSH_CMSG_AUTH_PASSWORD: |
| if (!options.password_authentication) { |
| verbose("Password authentication disabled."); |
| break; |
| } |
| /* |
| * Read user password. It is in plain text, but was |
| * transmitted over the encrypted channel so it is |
| * not visible to an outside observer. |
| */ |
| password = packet_get_string(&dlen); |
| packet_integrity_check(plen, 4 + dlen, type); |
| |
| #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 */ |
| |
| memset(password, 0, strlen(password)); |
| xfree(password); |
| break; |
| |
| #ifdef SKEY /* ISSUE: Is this right? we don't define |
| having skey_authentication in |
| servconf.h by default so I assume |
| we need to deal with this via #ifdef |
| in some reasonable way */ |
| case SSH_CMSG_AUTH_TIS: |
| debug("rcvd SSH_CMSG_AUTH_TIS"); |
| if (options.skey_authentication == 1) { |
| char *challenge = get_challenge(authctxt, authctxt->style); |
| if (challenge != NULL) { |
| debug("sending challenge '%s'", challenge); |
| packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE); |
| packet_put_cstring(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) { |
| char *response = packet_get_string(&dlen); |
| debug("got response '%s'", response); |
| packet_integrity_check(plen, 4 + dlen, type); |
| authenticated = verify_response(authctxt, response); |
| memset(response, 'r', dlen); |
| xfree(response); |
| } |
| break; |
| #endif /* ISSUE: End of wrong SKEY defines */ |
| |
| default: |
| /* |
| * Any unknown messages will be ignored (and failure |
| * returned) during authentication. |
| */ |
| log("Unknown message during authentication: type %d", type); |
| break; |
| } |
| if (!authctxt->valid && authenticated) |
| fatal("INTERNAL ERROR: authenticated invalid user %s", |
| authctxt->user); |
| |
| #ifdef HAVE_CYGWIN /* ISSUE: Right place? */ |
| if (authenticated && |
| !check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD,pw->pw_uid)) { |
| packet_disconnect("Authentication rejected for uid %d.", |
| (int)pw->pw_uid); |
| authenticated = 0; |
| } |
| #else |
| /* Special handling for root */ |
| if (authenticated && authctxt->pw->pw_uid == 0 && !auth_root_allowed()) |
| 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 (authenticated) |
| return; |
| |
| if (authctxt->failures++ > AUTH_FAIL_MAX) { |
| #ifdef WITH_AIXAUTHENTICATE |
| loginfailed(user,get_canonical_hostname(),"ssh"); |
| #endif /* WITH_AIXAUTHENTICATE */ |
| packet_disconnect(AUTH_FAIL_MSG, authctxt->user); |
| } |
| |
| 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 *authctxt; |
| struct passwd *pw; |
| int plen; |
| 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); |
| |
| /* Get the user name. */ |
| user = packet_get_string(&ulen); |
| packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER); |
| |
| if ((style = strchr(user, ':')) != NULL) |
| *style++ = 0; |
| |
| authctxt = authctxt_new(); |
| authctxt->user = user; |
| authctxt->style = style; |
| |
| setproctitle("%s", user); |
| |
| #ifdef AFS |
| /* If machine has AFS, set process authentication group. */ |
| if (k_hasafs()) { |
| k_setpag(); |
| k_unlog(); |
| } |
| #endif /* AFS */ |
| |
| /* Verify that the user is a valid user. */ |
| pw = getpwnam(user); |
| if (pw && allowed_user(pw)) { |
| authctxt->valid = 1; |
| pw = pwcopy(pw); |
| } else { |
| debug("do_authentication: illegal user %s", user); |
| pw = NULL; |
| } |
| authctxt->pw = pw; |
| |
| #ifdef USE_PAM |
| if (pw) |
| start_pam(user); |
| #endif |
| |
| /* |
| * If we are not running as root, the user must have the same uid as |
| * the server. (Unless you are running Windows) |
| */ |
| #ifndef HAVE_CYGWIN |
| if (getuid() != 0 && pw && pw->pw_uid != getuid()) |
| packet_disconnect("Cannot change user when server not running as root."); |
| #endif |
| |
| /* |
| * 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. */ |
| packet_start(SSH_SMSG_SUCCESS); |
| packet_send(); |
| packet_write_wait(); |
| |
| #ifdef WITH_AIXAUTHENTICATE |
| /* We don't have a pty yet, so just label the line as "ssh" */ |
| if (loginsuccess(authctxt->user,get_canonical_hostname(),"ssh",&aixloginmsg) < 0) |
| aixloginmsg = NULL; |
| #endif /* WITH_AIXAUTHENTICATE */ |
| |
| xfree(authctxt->user); |
| xfree(authctxt); |
| |
| /* Perform session preparation. */ |
| do_authenticated(pw); |
| } |