- dugsong@cvs.openbsd.org 2001/06/26 16:15:25

     [auth1.c auth.h auth-krb4.c auth-passwd.c readconf.c readconf.h
      servconf.c servconf.h session.c sshconnect1.c sshd.c]
     Kerberos v5 support for SSH1, mostly from Assar Westerlund
     <assar@freebsd.org> and Bjorn Gronvall <bg@sics.se>. markus@ ok

1 files changed, 172 insertions, 190 deletions

diff --git a/auth-krb4.c b/auth-krb4.c
index 8bb6e3d6f..031dcd301 100644
--- a/auth-krb4.c
+++ b/auth-krb4.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: auth-krb4.c,v 1.23 2001/01/22 08:15:00 markus Exp $");
+RCSID("$OpenBSD: auth-krb4.c,v 1.24 2001/06/26 16:15:22 dugsong Exp $");
 
 #include "ssh.h"
 #include "ssh1.h"
@@ -31,6 +31,7 @@ RCSID("$OpenBSD: auth-krb4.c,v 1.23 2001/01/22 08:15:00 markus Exp $");
 #include "xmalloc.h"
 #include "log.h"
 #include "servconf.h"
+#include "uidswap.h"
 #include "auth.h"
 
 #ifdef AFS
@@ -38,70 +39,114 @@ RCSID("$OpenBSD: auth-krb4.c,v 1.23 2001/01/22 08:15:00 markus Exp $");
 #endif
 
 #ifdef KRB4
-char *ticket = NULL;
-
 extern ServerOptions options;
 
+static int
+krb4_init(void *context)
+{
+        static int cleanup_registered = 0;
+        Authctxt *authctxt = (Authctxt *)context;
+        const char *tkt_root = TKT_ROOT;
+        struct stat st;
+        int fd;
+        
+        if (!authctxt->krb4_ticket_file) {
+                /* Set unique ticket string manually since we're still root. */
+                authctxt->krb4_ticket_file = xmalloc(MAXPATHLEN);
+#ifdef AFS
+                if (lstat("/ticket", &st) != -1)
+                        tkt_root = "/ticket/";
+#endif /* AFS */
+                snprintf(authctxt->krb4_ticket_file, MAXPATHLEN, "%s%u_%d",
+                    tkt_root, authctxt->pw->pw_uid, getpid());
+                krb_set_tkt_string(authctxt->krb4_ticket_file);
+        }
+        /* Register ticket cleanup in case of fatal error. */
+        if (!cleanup_registered) {
+                fatal_add_cleanup(krb4_cleanup_proc, authctxt);
+                cleanup_registered = 1;
+        }
+        /* Try to create our ticket file. */
+        if ((fd = mkstemp(authctxt->krb4_ticket_file)) != -1) {
+                close(fd);
+                return (1);
+        }
+        /* Ticket file exists - make sure user owns it (just passed ticket). */
+        if (lstat(authctxt->krb4_ticket_file, &st) != -1) {
+                if (st.st_mode == (S_IFREG | S_IRUSR | S_IWUSR) &&
+                    st.st_uid == authctxt->pw->pw_uid)
+                        return (1);
+        }
+        /* Failure - cancel cleanup function, leaving ticket for inspection. */
+        log("WARNING: bad ticket file %s", authctxt->krb4_ticket_file);
+        
+        fatal_remove_cleanup(krb4_cleanup_proc, authctxt);
+        cleanup_registered = 0;
+        
+        xfree(authctxt->krb4_ticket_file);
+        authctxt->krb4_ticket_file = NULL;
+        
+        return (0);
+}
+
 /*
  * 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_krb4_password(Authctxt *authctxt, const char *password)
 {
         AUTH_DAT adata;
         KTEXT_ST tkt;
         struct hostent *hp;
-        u_long faddr;
-        char localhost[MAXHOSTNAMELEN];
-        char phost[INST_SZ];
-        char realm[REALM_SZ];
+        struct passwd *pw;
+        char localhost[MAXHOSTNAMELEN], phost[INST_SZ], realm[REALM_SZ];
+        u_int32_t faddr;
         int r;
-
+        
+        if ((pw = authctxt->pw) == NULL)
+                return (0);
+        
         /*
          * 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)) {
+                if (!krb4_init(authctxt)) {
                         log("Couldn't initialize Kerberos ticket file for %s!",
                             pw->pw_name);
-                        goto kerberos_auth_failure;
+                        goto 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);
+                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;
+                        debug("Kerberos v4 password authentication for %s "
+                            "failed: %s", pw->pw_name, krb_err_txt[r]);
+                        goto 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);
+                gethostname(localhost, sizeof(localhost));
+                strlcpy(phost, (char *)krb_get_phost(localhost),
+                    sizeof(phost));
                 r = krb_mk_req(&tkt, KRB4_SERVICE_NAME, phost, realm, 33);
-
+                
                 if (r == KSUCCESS) {
-                        if (!(hp = gethostbyname(localhost))) {
+                        if ((hp = gethostbyname(localhost)) == NULL) {
                                 log("Couldn't get local host address!");
-                                goto kerberos_auth_failure;
+                                goto failure;
                         }
-                        memmove((void *) &faddr, (void *) hp->h_addr,
+                        memmove((void *)&faddr, (void *)hp->h_addr,
                             sizeof(faddr));
-
+                        
                         /* Verify our "rcmd" ticket. */
                         r = krb_rd_req(&tkt, KRB4_SERVICE_NAME, phost,
                             faddr, &adata, "");
@@ -110,119 +155,74 @@ auth_krb4_password(struct passwd * pw, const char *password)
                                  * Probably didn't have a srvtab on
                                  * localhost. Disallow login.
                                  */
-                                log("Kerberos V4 TGT for %s unverifiable, "
+                                log("Kerberos v4 TGT for %s unverifiable, "
                                     "no srvtab installed? krb_rd_req: %s",
                                     pw->pw_name, krb_err_txt[r]);
-                                goto kerberos_auth_failure;
+                                goto failure;
                         } else if (r != KSUCCESS) {
-                                log("Kerberos V4 %s ticket unverifiable: %s",
+                                log("Kerberos v4 %s ticket unverifiable: %s",
                                     KRB4_SERVICE_NAME, krb_err_txt[r]);
-                                goto kerberos_auth_failure;
+                                goto failure;
                         }
                 } else if (r == KDC_PR_UNKNOWN) {
                         /*
                          * Disallow login if no rcmd service exists, and
                          * log the error.
                          */
-                        log("Kerberos V4 TGT for %s unverifiable: %s; %s.%s "
+                        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);
-                        goto kerberos_auth_failure;
+                            krb_err_txt[r], KRB4_SERVICE_NAME, phost);
+                        goto failure;
                 } 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;
+                        debug("WARNING: Kerberos v4 TGT possibly spoofed "
+                            "for %s: %s", pw->pw_name, krb_err_txt[r]);
+                        goto failure;
                 }
-
                 /* Authentication succeeded. */
-                return 1;
-
-kerberos_auth_failure:
-                krb4_cleanup_proc(NULL);
-
-                if (!options.kerberos_or_local_passwd)
-                        return 0;
-        } else {
+                return (1);
+        } else
                 /* Logging in as root or no local Kerberos realm. */
-                packet_send_debug("Unable to authenticate to Kerberos.");
-        }
+                debug("Unable to authenticate to Kerberos.");
+        
+ failure:
+        krb4_cleanup_proc(authctxt);
+        
+        if (!options.kerberos_or_local_passwd)
+                return (0);
+        
         /* Fall back to ordinary passwd authentication. */
-        return -1;
+        return (-1);
 }
 
 void
-krb4_cleanup_proc(void *ignore)
+krb4_cleanup_proc(void *context)
 {
+        Authctxt *authctxt = (Authctxt *)context;
         debug("krb4_cleanup_proc called");
-        if (ticket) {
+        if (authctxt->krb4_ticket_file) {
                 (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%u_%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;
+                xfree(authctxt->krb4_ticket_file);
+                authctxt->krb4_ticket_file = NULL;
         }
-        /* 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_krb4(Authctxt *authctxt, KTEXT auth, char **client)
 {
         AUTH_DAT adat = {0};
         KTEXT_ST reply;
+        Key_schedule schedule;
+        struct sockaddr_in local, foreign;
         char instance[INST_SZ];
-        int r, s;
         socklen_t slen;
         u_int cksum;
-        Key_schedule schedule;
-        struct sockaddr_in local, foreign;
-
+        int r, s;
+        
         s = packet_get_connection_in();
-
+        
         slen = sizeof(local);
         memset(&local, 0, sizeof(local));
         if (getsockname(s, (struct sockaddr *) & local, &slen) < 0)
@@ -235,157 +235,139 @@ auth_krb4(const char *server_user, KTEXT auth, char **client)
         }
         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;
+        if ((r = krb_rd_req(auth, KRB4_SERVICE_NAME, instance,
+            0, &adat, ""))) {
+                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);
+        if (kuserok(&adat, authctxt->user) != KSUCCESS) {
+                log("Kerberos v4 .klogin authorization failed for %s to "
+                    "account %s", *client, authctxt->user);
                 xfree(*client);
-                return 0;
+                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]);
+                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;
+        return (1);
 }
 #endif /* KRB4 */
 
 #ifdef AFS
 int
-auth_kerberos_tgt(struct passwd *pw, const char *string)
+auth_krb4_tgt(Authctxt *authctxt, const char *string)
 {
         CREDENTIALS creds;
-
-        if (pw == NULL)
-                goto auth_kerberos_tgt_failure;
+        struct passwd *pw;
+        
+        if ((pw = authctxt->pw) == NULL)
+                goto failure;
+        
+        temporarily_use_uid(pw);
+        
         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;
+                log("Protocol error decoding Kerberos v4 TGT");
+                goto 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",
+                log("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;
+                goto failure;
         }
-        if (!krb4_init(pw->pw_uid))
-                goto auth_kerberos_tgt_failure;
-
+        if (!krb4_init(authctxt))
+                goto failure;
+        
         if (in_tkt(creds.pname, creds.pinst) != KSUCCESS)
-                goto auth_kerberos_tgt_failure;
-
+                goto 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;
+            creds.session, creds.lifetime, creds.kvno, &creds.ticket_st,
+            creds.issue_date) != KSUCCESS) {
+                debug("Kerberos v4 TGT refused: couldn't save credentials");
+                goto 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);
+        
+        debug("Kerberos v4 TGT accepted (%s%s%s@%s)",
+            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);
+        
+        restore_uid();
+        
+        return (1);
+        
+ failure:
+        krb4_cleanup_proc(authctxt);
         memset(&creds, 0, sizeof(creds));
-        packet_start(SSH_SMSG_FAILURE);
-        packet_send();
-        packet_write_wait();
-        return 0;
+        restore_uid();
+        
+        return (0);
 }
 
 int
-auth_afs_token(struct passwd *pw, const char *token_string)
+auth_afs_token(Authctxt *authctxt, const char *token_string)
 {
         CREDENTIALS creds;
+        struct passwd *pw;
         uid_t uid;
-
-        if (pw == NULL) {
-                /* XXX fake protocol error */
-                packet_send_debug("Protocol error decoding AFS token");
-                packet_start(SSH_SMSG_FAILURE);
-                packet_send();
-                packet_write_wait();
-                return 0;
-        }
+        
+        if ((pw = authctxt->pw) == NULL)
+                return (0);
+        
         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;
+                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);
         else
                 uid = pw->pw_uid;
-
+        
         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);
+                log("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;
+                return (0);
         }
-        packet_send_debug("AFS token accepted (%s@%s, %s@%s)", creds.service,
-            creds.realm, creds.pname, creds.realm);
+        debug("AFS token accepted (%s@%s)", creds.pname, creds.realm);
         memset(&creds, 0, sizeof(creds));
-        packet_start(SSH_SMSG_SUCCESS);
-        packet_send();
-        packet_write_wait();
-        return 1;
+        
+        return (1);
 }
 #endif /* AFS */