| /* |
| * Dug Song <dugsong@UMICH.EDU> |
| * Kerberos v4 authentication and ticket-passing routines. |
| */ |
| |
| #include "includes.h" |
| #include "packet.h" |
| #include "xmalloc.h" |
| #include "ssh.h" |
| #include "servconf.h" |
| |
| #ifdef KRB4 |
| char *ticket = NULL; |
| |
| extern ServerOptions options; |
| |
| /* |
| * try krb4 authentication, |
| * return 1 on success, 0 on failure, -1 if krb4 is not available |
| */ |
| |
| int |
| auth_krb4_password(struct passwd * pw, const char *password) |
| { |
| AUTH_DAT adata; |
| KTEXT_ST tkt; |
| struct hostent *hp; |
| unsigned long faddr; |
| char localhost[MAXHOSTNAMELEN]; |
| char phost[INST_SZ]; |
| char realm[REALM_SZ]; |
| int r; |
| |
| /* |
| * Try Kerberos password authentication only for non-root |
| * users and only if Kerberos is installed. |
| */ |
| if (pw->pw_uid != 0 && krb_get_lrealm(realm, 1) == KSUCCESS) { |
| |
| /* Set up our ticket file. */ |
| if (!krb4_init(pw->pw_uid)) { |
| log("Couldn't initialize Kerberos ticket file for %s!", |
| pw->pw_name); |
| goto kerberos_auth_failure; |
| } |
| /* Try to get TGT using our password. */ |
| r = krb_get_pw_in_tkt((char *) pw->pw_name, "", |
| realm, "krbtgt", realm, |
| DEFAULT_TKT_LIFE, (char *) password); |
| if (r != INTK_OK) { |
| packet_send_debug("Kerberos V4 password " |
| "authentication for %s failed: %s", |
| pw->pw_name, krb_err_txt[r]); |
| goto kerberos_auth_failure; |
| } |
| /* Successful authentication. */ |
| chown(tkt_string(), pw->pw_uid, pw->pw_gid); |
| |
| /* |
| * Now that we have a TGT, try to get a local |
| * "rcmd" ticket to ensure that we are not talking |
| * to a bogus Kerberos server. |
| */ |
| (void) gethostname(localhost, sizeof(localhost)); |
| (void) strlcpy(phost, (char *) krb_get_phost(localhost), |
| INST_SZ); |
| r = krb_mk_req(&tkt, KRB4_SERVICE_NAME, phost, realm, 33); |
| |
| if (r == KSUCCESS) { |
| if (!(hp = gethostbyname(localhost))) { |
| log("Couldn't get local host address!"); |
| goto kerberos_auth_failure; |
| } |
| memmove((void *) &faddr, (void *) hp->h_addr, |
| sizeof(faddr)); |
| |
| /* Verify our "rcmd" ticket. */ |
| r = krb_rd_req(&tkt, KRB4_SERVICE_NAME, phost, |
| faddr, &adata, ""); |
| if (r == RD_AP_UNDEC) { |
| /* |
| * Probably didn't have a srvtab on |
| * localhost. Allow login. |
| */ |
| log("Kerberos V4 TGT for %s unverifiable, " |
| "no srvtab installed? krb_rd_req: %s", |
| pw->pw_name, krb_err_txt[r]); |
| } else if (r != KSUCCESS) { |
| log("Kerberos V4 %s ticket unverifiable: %s", |
| KRB4_SERVICE_NAME, krb_err_txt[r]); |
| goto kerberos_auth_failure; |
| } |
| } else if (r == KDC_PR_UNKNOWN) { |
| /* |
| * Allow login if no rcmd service exists, but |
| * log the error. |
| */ |
| log("Kerberos V4 TGT for %s unverifiable: %s; %s.%s " |
| "not registered, or srvtab is wrong?", pw->pw_name, |
| krb_err_txt[r], KRB4_SERVICE_NAME, phost); |
| } else { |
| /* |
| * TGT is bad, forget it. Possibly spoofed! |
| */ |
| packet_send_debug("WARNING: Kerberos V4 TGT " |
| "possibly spoofed for %s: %s", |
| pw->pw_name, krb_err_txt[r]); |
| goto kerberos_auth_failure; |
| } |
| |
| /* Authentication succeeded. */ |
| return 1; |
| |
| kerberos_auth_failure: |
| krb4_cleanup_proc(NULL); |
| |
| if (!options.kerberos_or_local_passwd) |
| return 0; |
| } else { |
| /* Logging in as root or no local Kerberos realm. */ |
| packet_send_debug("Unable to authenticate to Kerberos."); |
| } |
| /* Fall back to ordinary passwd authentication. */ |
| return -1; |
| } |
| |
| void |
| krb4_cleanup_proc(void *ignore) |
| { |
| debug("krb4_cleanup_proc called"); |
| if (ticket) { |
| (void) dest_tkt(); |
| xfree(ticket); |
| ticket = NULL; |
| } |
| } |
| |
| int |
| krb4_init(uid_t uid) |
| { |
| static int cleanup_registered = 0; |
| const char *tkt_root = TKT_ROOT; |
| struct stat st; |
| int fd; |
| |
| if (!ticket) { |
| /* Set unique ticket string manually since we're still root. */ |
| ticket = xmalloc(MAXPATHLEN); |
| #ifdef AFS |
| if (lstat("/ticket", &st) != -1) |
| tkt_root = "/ticket/"; |
| #endif /* AFS */ |
| snprintf(ticket, MAXPATHLEN, "%s%d_%d", tkt_root, uid, getpid()); |
| (void) krb_set_tkt_string(ticket); |
| } |
| /* Register ticket cleanup in case of fatal error. */ |
| if (!cleanup_registered) { |
| fatal_add_cleanup(krb4_cleanup_proc, NULL); |
| cleanup_registered = 1; |
| } |
| /* Try to create our ticket file. */ |
| if ((fd = mkstemp(ticket)) != -1) { |
| close(fd); |
| return 1; |
| } |
| /* Ticket file exists - make sure user owns it (just passed ticket). */ |
| if (lstat(ticket, &st) != -1) { |
| if (st.st_mode == (S_IFREG | S_IRUSR | S_IWUSR) && |
| st.st_uid == uid) |
| return 1; |
| } |
| /* Failure - cancel cleanup function, leaving bad ticket for inspection. */ |
| log("WARNING: bad ticket file %s", ticket); |
| fatal_remove_cleanup(krb4_cleanup_proc, NULL); |
| cleanup_registered = 0; |
| xfree(ticket); |
| ticket = NULL; |
| |
| return 0; |
| } |
| |
| int |
| auth_krb4(const char *server_user, KTEXT auth, char **client) |
| { |
| AUTH_DAT adat = {0}; |
| KTEXT_ST reply; |
| char instance[INST_SZ]; |
| int r, s; |
| socklen_t slen; |
| u_int cksum; |
| Key_schedule schedule; |
| struct sockaddr_in local, foreign; |
| |
| s = packet_get_connection_in(); |
| |
| slen = sizeof(local); |
| memset(&local, 0, sizeof(local)); |
| if (getsockname(s, (struct sockaddr *) & local, &slen) < 0) |
| debug("getsockname failed: %.100s", strerror(errno)); |
| slen = sizeof(foreign); |
| memset(&foreign, 0, sizeof(foreign)); |
| if (getpeername(s, (struct sockaddr *) & foreign, &slen) < 0) { |
| debug("getpeername failed: %.100s", strerror(errno)); |
| fatal_cleanup(); |
| } |
| instance[0] = '*'; |
| instance[1] = 0; |
| |
| /* Get the encrypted request, challenge, and session key. */ |
| if ((r = krb_rd_req(auth, KRB4_SERVICE_NAME, instance, 0, &adat, ""))) { |
| packet_send_debug("Kerberos V4 krb_rd_req: %.100s", krb_err_txt[r]); |
| return 0; |
| } |
| des_key_sched((des_cblock *) adat.session, schedule); |
| |
| *client = xmalloc(MAX_K_NAME_SZ); |
| (void) snprintf(*client, MAX_K_NAME_SZ, "%s%s%s@%s", adat.pname, |
| *adat.pinst ? "." : "", adat.pinst, adat.prealm); |
| |
| /* Check ~/.klogin authorization now. */ |
| if (kuserok(&adat, (char *) server_user) != KSUCCESS) { |
| packet_send_debug("Kerberos V4 .klogin authorization failed!"); |
| log("Kerberos V4 .klogin authorization failed for %s to account %s", |
| *client, server_user); |
| xfree(*client); |
| return 0; |
| } |
| /* Increment the checksum, and return it encrypted with the |
| session key. */ |
| cksum = adat.checksum + 1; |
| cksum = htonl(cksum); |
| |
| /* If we can't successfully encrypt the checksum, we send back an |
| empty message, admitting our failure. */ |
| if ((r = krb_mk_priv((u_char *) & cksum, reply.dat, sizeof(cksum) + 1, |
| schedule, &adat.session, &local, &foreign)) < 0) { |
| packet_send_debug("Kerberos V4 mk_priv: (%d) %s", r, krb_err_txt[r]); |
| reply.dat[0] = 0; |
| reply.length = 0; |
| } else |
| reply.length = r; |
| |
| /* Clear session key. */ |
| memset(&adat.session, 0, sizeof(&adat.session)); |
| |
| packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE); |
| packet_put_string((char *) reply.dat, reply.length); |
| packet_send(); |
| packet_write_wait(); |
| return 1; |
| } |
| #endif /* KRB4 */ |
| |
| #ifdef AFS |
| int |
| auth_kerberos_tgt(struct passwd *pw, const char *string) |
| { |
| CREDENTIALS creds; |
| |
| if (!radix_to_creds(string, &creds)) { |
| log("Protocol error decoding Kerberos V4 tgt"); |
| packet_send_debug("Protocol error decoding Kerberos V4 tgt"); |
| goto auth_kerberos_tgt_failure; |
| } |
| if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */ |
| strlcpy(creds.service, "krbtgt", sizeof creds.service); |
| |
| if (strcmp(creds.service, "krbtgt")) { |
| log("Kerberos V4 tgt (%s%s%s@%s) rejected for %s", creds.pname, |
| creds.pinst[0] ? "." : "", creds.pinst, creds.realm, |
| pw->pw_name); |
| packet_send_debug("Kerberos V4 tgt (%s%s%s@%s) rejected for %s", |
| creds.pname, creds.pinst[0] ? "." : "", creds.pinst, |
| creds.realm, pw->pw_name); |
| goto auth_kerberos_tgt_failure; |
| } |
| if (!krb4_init(pw->pw_uid)) |
| goto auth_kerberos_tgt_failure; |
| |
| if (in_tkt(creds.pname, creds.pinst) != KSUCCESS) |
| goto auth_kerberos_tgt_failure; |
| |
| if (save_credentials(creds.service, creds.instance, creds.realm, |
| creds.session, creds.lifetime, creds.kvno, |
| &creds.ticket_st, creds.issue_date) != KSUCCESS) { |
| packet_send_debug("Kerberos V4 tgt refused: couldn't save credentials"); |
| goto auth_kerberos_tgt_failure; |
| } |
| /* Successful authentication, passed all checks. */ |
| chown(tkt_string(), pw->pw_uid, pw->pw_gid); |
| |
| packet_send_debug("Kerberos V4 tgt accepted (%s.%s@%s, %s%s%s@%s)", |
| creds.service, creds.instance, creds.realm, creds.pname, |
| creds.pinst[0] ? "." : "", creds.pinst, creds.realm); |
| memset(&creds, 0, sizeof(creds)); |
| packet_start(SSH_SMSG_SUCCESS); |
| packet_send(); |
| packet_write_wait(); |
| return 1; |
| |
| auth_kerberos_tgt_failure: |
| krb4_cleanup_proc(NULL); |
| memset(&creds, 0, sizeof(creds)); |
| packet_start(SSH_SMSG_FAILURE); |
| packet_send(); |
| packet_write_wait(); |
| return 0; |
| } |
| |
| int |
| auth_afs_token(struct passwd *pw, const char *token_string) |
| { |
| CREDENTIALS creds; |
| uid_t uid = pw->pw_uid; |
| |
| if (!radix_to_creds(token_string, &creds)) { |
| log("Protocol error decoding AFS token"); |
| packet_send_debug("Protocol error decoding AFS token"); |
| packet_start(SSH_SMSG_FAILURE); |
| packet_send(); |
| packet_write_wait(); |
| return 0; |
| } |
| if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */ |
| strlcpy(creds.service, "afs", sizeof creds.service); |
| |
| if (strncmp(creds.pname, "AFS ID ", 7) == 0) |
| uid = atoi(creds.pname + 7); |
| |
| if (kafs_settoken(creds.realm, uid, &creds)) { |
| log("AFS token (%s@%s) rejected for %s", creds.pname, creds.realm, |
| pw->pw_name); |
| packet_send_debug("AFS token (%s@%s) rejected for %s", creds.pname, |
| creds.realm, pw->pw_name); |
| memset(&creds, 0, sizeof(creds)); |
| packet_start(SSH_SMSG_FAILURE); |
| packet_send(); |
| packet_write_wait(); |
| return 0; |
| } |
| packet_send_debug("AFS token accepted (%s@%s, %s@%s)", creds.service, |
| creds.realm, creds.pname, creds.realm); |
| memset(&creds, 0, sizeof(creds)); |
| packet_start(SSH_SMSG_SUCCESS); |
| packet_send(); |
| packet_write_wait(); |
| return 1; |
| } |
| #endif /* AFS */ |