X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/8efc0c151a0f57612e1aa0abb5b7d536db4cf76a..8fb293f208b501d2774ba70603088242bd6baffe:/auth-krb4.c

diff --git a/auth-krb4.c b/auth-krb4.c
index 735b2053..fb0e20ce 100644
--- a/auth-krb4.c
+++ b/auth-krb4.c
@@ -1,209 +1,348 @@
 /*
-
-   auth-kerberos.c
-
-   Dug Song <dugsong@UMICH.EDU>
-
-   Kerberos v4 authentication and ticket-passing routines.
-
-   $Id$
-*/
+ *    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
-int ssh_tf_init(uid_t uid)
+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)
 {
-  extern char *ticket;
-  char *tkt_root = TKT_ROOT;
-  struct stat st;
-  int fd;
-  
-  /* Set unique ticket string manually since we're still root. */
-  ticket = xmalloc(MAXPATHLEN);
+	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/";
+		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);
-
-  /* Make sure we own this ticket file, and we created it. */
-  if (lstat(ticket, &st) == -1 && errno == ENOENT) {
-    /* good, no ticket file exists. create it. */
-    if ((fd = open(ticket, O_RDWR|O_CREAT|O_EXCL, 0600)) != -1) {
-      close(fd);
-      return 1;
-    }
-  }
-  else {
-    /* file exists. make sure server_user owns it (e.g. just passed ticket),
-       and that it isn't a symlink, and that it is mode 600. */
-    if (st.st_mode == (S_IFREG|S_IRUSR|S_IWUSR) && st.st_uid == uid)
-      return 1;
-  }
-  /* Failure. */
-  log("WARNING: bad ticket file %s", ticket);
-  return 0;
+		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)
+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));
-  
-  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);
-    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;
+	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)
+int 
+auth_kerberos_tgt(struct passwd *pw, const char *string)
 {
-  CREDENTIALS creds;
-  extern char *ticket;
-  int r;
-  
-  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 uid %d",
-	creds.pname, creds.pinst[0] ? "." : "", creds.pinst, creds.realm,
-	pw->pw_uid);
-    packet_send_debug("Kerberos V4 tgt (%s%s%s@%s) rejected for uid %d",
-		      creds.pname, creds.pinst[0] ? "." : "", creds.pinst,
-		      creds.realm, pw->pw_uid);
-    goto auth_kerberos_tgt_failure;
-  }
-  if (!ssh_tf_init(pw->pw_uid) ||
-      (r = in_tkt(creds.pname, creds.pinst)) ||
-      (r = save_credentials(creds.service, creds.instance, creds.realm,
-			    creds.session, creds.lifetime, creds.kvno,
-			    &creds.ticket_st, creds.issue_date))) {
-    xfree(ticket);
-    ticket = NULL;
-    packet_send_debug("Kerberos V4 tgt refused: couldn't save credentials");
-    goto auth_kerberos_tgt_failure;
-  }
-  /* Successful authentication, passed all checks. */
-  chown(ticket, 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);
-  
-  packet_start(SSH_SMSG_SUCCESS);
-  packet_send();
-  packet_write_wait();
-  return 1;
+	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:
-  memset(&creds, 0, sizeof(creds));
-  packet_start(SSH_SMSG_FAILURE);
-  packet_send();
-  packet_write_wait();
-  return 0;
+	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(char *server_user, uid_t uid, const char *string)
+int 
+auth_afs_token(struct passwd *pw, const char *token_string)
 {
-  CREDENTIALS creds;
-
-  if (!radix_to_creds(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 uid %d", creds.pname,
-	creds.realm, uid);
-    packet_send_debug("AFS token (%s@%s) rejected for uid %d", creds.pname,
-		      creds.realm, uid);
-    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);
-  packet_start(SSH_SMSG_SUCCESS);
-  packet_send();
-  packet_write_wait();
-  return 1;
+	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 */