diff options
Diffstat (limited to 'crypto/openssh/auth-krb4.c')
| -rw-r--r-- | crypto/openssh/auth-krb4.c | 348 |
1 files changed, 348 insertions, 0 deletions
diff --git a/crypto/openssh/auth-krb4.c b/crypto/openssh/auth-krb4.c new file mode 100644 index 0000000..fb0e20c --- /dev/null +++ b/crypto/openssh/auth-krb4.c @@ -0,0 +1,348 @@ +/* + * 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; + 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; + u_int cksum; + Key_schedule schedule; + struct sockaddr_in local, foreign; + + s = packet_get_connection_in(); + + r = sizeof(local); + memset(&local, 0, sizeof(local)); + if (getsockname(s, (struct sockaddr *) & local, &r) < 0) + debug("getsockname failed: %.100s", strerror(errno)); + r = sizeof(foreign); + memset(&foreign, 0, sizeof(foreign)); + if (getpeername(s, (struct sockaddr *) & foreign, &r) < 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 */ |
