/*
-
- 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 */
andersk / openssh.git / blobdiff