s3: Change sockaddr util function names for consistency
[samba.git] / source3 / libads / kerberos.c
index 57233f218281db1727a0c43387cafc9993da9bef..7dfc19b4628573f7304eaffa595462a65766758c 100644 (file)
@@ -9,7 +9,7 @@
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 2 of the License, or
+   the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.
    
    This program is distributed in the hope that it will be useful,
    GNU General Public License for more details.
    
    You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software
-   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 #include "includes.h"
 
 #ifdef HAVE_KRB5
 
+#define DEFAULT_KRB5_PORT 88
+
 #define LIBADS_CCACHE_NAME "MEMORY:libads"
 
 /*
@@ -55,6 +56,127 @@ kerb_prompter(krb5_context ctx, void *data,
        return 0;
 }
 
+static bool smb_krb5_err_io_nstatus(TALLOC_CTX *mem_ctx, 
+                                   DATA_BLOB *edata_blob, 
+                                   KRB5_EDATA_NTSTATUS *edata)
+{
+       bool ret = False;
+       prs_struct ps;
+
+       if (!mem_ctx || !edata_blob || !edata) 
+               return False;
+
+       if (!prs_init(&ps, edata_blob->length, mem_ctx, UNMARSHALL))
+               return False;
+
+       if (!prs_copy_data_in(&ps, (char *)edata_blob->data, edata_blob->length))
+               goto out;
+
+       prs_set_offset(&ps, 0);
+
+       if (!prs_ntstatus("ntstatus", &ps, 1, &edata->ntstatus))
+               goto out;
+
+       if (!prs_uint32("unknown1", &ps, 1, &edata->unknown1))
+               goto out;
+
+       if (!prs_uint32("unknown2", &ps, 1, &edata->unknown2)) /* only seen 00000001 here */
+               goto out;
+
+       ret = True;
+ out:
+       prs_mem_free(&ps);
+
+       return ret;
+}
+
+ static bool smb_krb5_get_ntstatus_from_krb5_error(krb5_error *error,
+                                                  NTSTATUS *nt_status)
+{
+       DATA_BLOB edata;
+       DATA_BLOB unwrapped_edata;
+       TALLOC_CTX *mem_ctx;
+       KRB5_EDATA_NTSTATUS parsed_edata;
+
+#ifdef HAVE_E_DATA_POINTER_IN_KRB5_ERROR
+       edata = data_blob(error->e_data->data, error->e_data->length);
+#else
+       edata = data_blob(error->e_data.data, error->e_data.length);
+#endif /* HAVE_E_DATA_POINTER_IN_KRB5_ERROR */
+
+#ifdef DEVELOPER
+       dump_data(10, edata.data, edata.length);
+#endif /* DEVELOPER */
+
+       mem_ctx = talloc_init("smb_krb5_get_ntstatus_from_krb5_error");
+       if (mem_ctx == NULL) {
+               data_blob_free(&edata);
+               return False;
+       }
+
+       if (!unwrap_edata_ntstatus(mem_ctx, &edata, &unwrapped_edata)) {
+               data_blob_free(&edata);
+               TALLOC_FREE(mem_ctx);
+               return False;
+       }
+
+       data_blob_free(&edata);
+
+       if (!smb_krb5_err_io_nstatus(mem_ctx, &unwrapped_edata, &parsed_edata)) {
+               data_blob_free(&unwrapped_edata);
+               TALLOC_FREE(mem_ctx);
+               return False;
+       }
+
+       data_blob_free(&unwrapped_edata);
+
+       if (nt_status) {
+               *nt_status = parsed_edata.ntstatus;
+       }
+
+       TALLOC_FREE(mem_ctx);
+
+       return True;
+}
+
+ static bool smb_krb5_get_ntstatus_from_krb5_error_init_creds_opt(krb5_context ctx, 
+                                                                 krb5_get_init_creds_opt *opt, 
+                                                                 NTSTATUS *nt_status)
+{
+       bool ret = False;
+       krb5_error *error = NULL;
+
+#ifdef HAVE_KRB5_GET_INIT_CREDS_OPT_GET_ERROR
+       ret = krb5_get_init_creds_opt_get_error(ctx, opt, &error);
+       if (ret) {
+               DEBUG(1,("krb5_get_init_creds_opt_get_error gave: %s\n", 
+                       error_message(ret)));
+               return False;
+       }
+#endif /* HAVE_KRB5_GET_INIT_CREDS_OPT_GET_ERROR */
+
+       if (!error) {
+               DEBUG(1,("no krb5_error\n"));
+               return False;
+       }
+
+#ifdef HAVE_E_DATA_POINTER_IN_KRB5_ERROR
+       if (!error->e_data) {
+#else
+       if (error->e_data.data == NULL) {
+#endif /* HAVE_E_DATA_POINTER_IN_KRB5_ERROR */
+               DEBUG(1,("no edata in krb5_error\n")); 
+               krb5_free_error(ctx, error);
+               return False;
+       }
+
+       ret = smb_krb5_get_ntstatus_from_krb5_error(error, nt_status);
+
+       krb5_free_error(ctx, error);
+
+       return ret;
+}
+
 /*
   simulate a kinit, putting the tgt in the given cache location. If cache_name == NULL
   place in default cache location.
@@ -66,88 +188,79 @@ int kerberos_kinit_password_ext(const char *principal,
                                time_t *expire_time,
                                time_t *renew_till_time,
                                const char *cache_name,
-                               BOOL request_pac,
-                               BOOL add_netbios_addr,
-                               time_t renewable_time)
+                               bool request_pac,
+                               bool add_netbios_addr,
+                               time_t renewable_time,
+                               NTSTATUS *ntstatus)
 {
        krb5_context ctx = NULL;
        krb5_error_code code = 0;
        krb5_ccache cc = NULL;
-       krb5_principal me;
+       krb5_principal me = NULL;
        krb5_creds my_creds;
-       krb5_get_init_creds_opt opt;
+       krb5_get_init_creds_opt *opt = NULL;
        smb_krb5_addresses *addr = NULL;
 
+       ZERO_STRUCT(my_creds);
+
        initialize_krb5_error_table();
        if ((code = krb5_init_context(&ctx)))
-               return code;
+               goto out;
 
        if (time_offset != 0) {
                krb5_set_real_time(ctx, time(NULL) + time_offset, 0);
        }
 
-       DEBUG(10,("kerberos_kinit_password: using %s as ccache\n",
-                       cache_name ? cache_name: krb5_cc_default_name(ctx)));
+       DEBUG(10,("kerberos_kinit_password: as %s using [%s] as ccache and config [%s]\n",
+                       principal,
+                       cache_name ? cache_name: krb5_cc_default_name(ctx),
+                       getenv("KRB5_CONFIG")));
 
        if ((code = krb5_cc_resolve(ctx, cache_name ? cache_name : krb5_cc_default_name(ctx), &cc))) {
-               krb5_free_context(ctx);
-               return code;
+               goto out;
        }
        
        if ((code = smb_krb5_parse_name(ctx, principal, &me))) {
-               krb5_free_context(ctx); 
-               return code;
+               goto out;
        }
 
-       krb5_get_init_creds_opt_init(&opt);
-       krb5_get_init_creds_opt_set_renew_life(&opt, renewable_time);
-       krb5_get_init_creds_opt_set_forwardable(&opt, 1);
-       
-       if (request_pac) {
+       if ((code = smb_krb5_get_init_creds_opt_alloc(ctx, &opt))) {
+               goto out;
+       }
+
+       krb5_get_init_creds_opt_set_renew_life(opt, renewable_time);
+       krb5_get_init_creds_opt_set_forwardable(opt, True);
+#if 0
+       /* insane testing */
+       krb5_get_init_creds_opt_set_tkt_life(opt, 60);
+#endif
+
 #ifdef HAVE_KRB5_GET_INIT_CREDS_OPT_SET_PAC_REQUEST
-               code = krb5_get_init_creds_opt_set_pac_request(ctx, &opt, True);
-               if (code) {
-                       krb5_free_principal(ctx, me);
-                       krb5_free_context(ctx);
-                       return code;
+       if (request_pac) {
+               if ((code = krb5_get_init_creds_opt_set_pac_request(ctx, opt, (krb5_boolean)request_pac))) {
+                       goto out;
                }
-#endif
        }
-
+#endif
        if (add_netbios_addr) {
-               code = smb_krb5_gen_netbios_krb5_address(&addr);
-               if (code) {
-                       krb5_free_principal(ctx, me);
-                       krb5_free_context(ctx);         
-                       return code;    
+               if ((code = smb_krb5_gen_netbios_krb5_address(&addr))) {
+                       goto out;
                }
-               krb5_get_init_creds_opt_set_address_list(&opt, addr->addrs);
+               krb5_get_init_creds_opt_set_address_list(opt, addr->addrs);
        }
 
        if ((code = krb5_get_init_creds_password(ctx, &my_creds, me, CONST_DISCARD(char *,password), 
-                                                kerb_prompter, NULL, 0, NULL, &opt)))
-       {
-               smb_krb5_free_addresses(ctx, addr);
-               krb5_free_principal(ctx, me);
-               krb5_free_context(ctx);         
-               return code;
+                                                kerb_prompter, CONST_DISCARD(char *,password),
+                                                0, NULL, opt))) {
+               goto out;
        }
-       
+
        if ((code = krb5_cc_initialize(ctx, cc, me))) {
-               smb_krb5_free_addresses(ctx, addr);
-               krb5_free_cred_contents(ctx, &my_creds);
-               krb5_free_principal(ctx, me);
-               krb5_free_context(ctx);         
-               return code;
+               goto out;
        }
        
        if ((code = krb5_cc_store_cred(ctx, cc, &my_creds))) {
-               krb5_cc_close(ctx, cc);
-               smb_krb5_free_addresses(ctx, addr);
-               krb5_free_cred_contents(ctx, &my_creds);
-               krb5_free_principal(ctx, me);
-               krb5_free_context(ctx);         
-               return code;
+               goto out;
        }
 
        if (expire_time) {
@@ -157,14 +270,47 @@ int kerberos_kinit_password_ext(const char *principal,
        if (renew_till_time) {
                *renew_till_time = (time_t) my_creds.times.renew_till;
        }
+ out:
+       if (ntstatus) {
+
+               NTSTATUS status;
+
+               /* fast path */
+               if (code == 0) {
+                       *ntstatus = NT_STATUS_OK;
+                       goto cleanup;
+               }
+
+               /* try to get ntstatus code out of krb5_error when we have it
+                * inside the krb5_get_init_creds_opt - gd */
+
+               if (opt && smb_krb5_get_ntstatus_from_krb5_error_init_creds_opt(ctx, opt, &status)) {
+                       *ntstatus = status;
+                       goto cleanup;
+               }
+
+               /* fall back to self-made-mapping */
+               *ntstatus = krb5_to_nt_status(code);
+       }
 
-       krb5_cc_close(ctx, cc);
-       smb_krb5_free_addresses(ctx, addr);
+ cleanup:
        krb5_free_cred_contents(ctx, &my_creds);
-       krb5_free_principal(ctx, me);
-       krb5_free_context(ctx);         
-       
-       return 0;
+       if (me) {
+               krb5_free_principal(ctx, me);
+       }
+       if (addr) {
+               smb_krb5_free_addresses(ctx, addr);
+       }
+       if (opt) {
+               smb_krb5_get_init_creds_opt_free(ctx, opt);
+       }
+       if (cc) {
+               krb5_cc_close(ctx, cc);
+       }
+       if (ctx) {
+               krb5_free_context(ctx);
+       }
+       return code;
 }
 
 
@@ -177,6 +323,11 @@ int ads_kinit_password(ADS_STRUCT *ads)
        const char *account_name;
        fstring acct_name;
 
+       if (ads->auth.flags & ADS_AUTH_USER_CREDS) {
+               account_name = ads->auth.user_name;
+               goto got_accountname;
+       }
+
        if ( IS_DC ) {
                /* this will end up getting a ticket for DOMAIN@RUSTED.REA.LM */
                account_name = lp_workgroup();
@@ -192,6 +343,7 @@ int ads_kinit_password(ADS_STRUCT *ads)
                        account_name = ads->auth.user_name;
        }
 
+ got_accountname:
        if (asprintf(&s, "%s@%s", account_name, ads->auth.realm) == -1) {
                return KRB5_CC_NOMEM;
        }
@@ -202,7 +354,8 @@ int ads_kinit_password(ADS_STRUCT *ads)
        }
        
        ret = kerberos_kinit_password_ext(s, ads->auth.password, ads->auth.time_offset,
-                       &ads->auth.expire, NULL, NULL, False, False, ads->auth.renewable);
+                       &ads->auth.tgt_expire, NULL, NULL, False, False, ads->auth.renewable, 
+                       NULL);
 
        if (ret) {
                DEBUG(0,("kerberos_kinit_password %s failed: %s\n", 
@@ -260,8 +413,8 @@ static char *kerberos_secrets_fetch_salting_principal(const char *service, int e
        char *key = NULL;
        char *ret = NULL;
 
-       asprintf(&key, "%s/%s/enctype=%d", SECRETS_SALTING_PRINCIPAL, service, enctype);
-       if (!key) {
+       if (asprintf(&key, "%s/%s/enctype=%d",
+                    SECRETS_SALTING_PRINCIPAL, service, enctype) == -1) {
                return NULL;
        }
        ret = (char *)secrets_fetch(key, NULL);
@@ -291,7 +444,10 @@ static char* des_salt_key( void )
 {
        char *key;
 
-       asprintf(&key, "%s/DES/%s", SECRETS_SALTING_PRINCIPAL, lp_realm());
+       if (asprintf(&key, "%s/DES/%s", SECRETS_SALTING_PRINCIPAL,
+                    lp_realm()) == -1) {
+               return NULL;
+       }
 
        return key;
 }
@@ -299,10 +455,10 @@ static char* des_salt_key( void )
 /************************************************************************
 ************************************************************************/
 
-BOOL kerberos_secrets_store_des_salt( const char* salt )
+bool kerberos_secrets_store_des_salt( const char* salt )
 {
        char* key;
-       BOOL ret;
+       bool ret;
 
        if ( (key = des_salt_key()) == NULL ) {
                DEBUG(0,("kerberos_secrets_store_des_salt: failed to generate key!\n"));
@@ -343,6 +499,61 @@ char* kerberos_secrets_fetch_des_salt( void )
        return salt;
 }
 
+/************************************************************************
+ Routine to get the default realm from the kerberos credentials cache.
+ Caller must free if the return value is not NULL.
+************************************************************************/
+
+char *kerberos_get_default_realm_from_ccache( void )
+{
+       char *realm = NULL;
+       krb5_context ctx = NULL;
+       krb5_ccache cc = NULL;
+       krb5_principal princ = NULL;
+
+       initialize_krb5_error_table();
+       if (krb5_init_context(&ctx)) {
+               return NULL;
+       }
+
+       DEBUG(5,("kerberos_get_default_realm_from_ccache: "
+               "Trying to read krb5 cache: %s\n",
+               krb5_cc_default_name(ctx)));
+       if (krb5_cc_default(ctx, &cc)) {
+               DEBUG(0,("kerberos_get_default_realm_from_ccache: "
+                       "failed to read default cache\n"));
+               goto out;
+       }
+       if (krb5_cc_get_principal(ctx, cc, &princ)) {
+               DEBUG(0,("kerberos_get_default_realm_from_ccache: "
+                       "failed to get default principal\n"));
+               goto out;
+       }
+
+#if defined(HAVE_KRB5_PRINCIPAL_GET_REALM)
+       realm = SMB_STRDUP(krb5_principal_get_realm(ctx, princ));
+#elif defined(HAVE_KRB5_PRINC_REALM)
+       {
+               krb5_data *realm_data = krb5_princ_realm(ctx, princ);
+               realm = SMB_STRNDUP(realm_data->data, realm_data->length);
+       }
+#endif
+
+  out:
+
+       if (princ) {
+               krb5_free_principal(ctx, princ);
+       }
+       if (cc) {
+               krb5_cc_close(ctx, cc);
+       }
+       if (ctx) {
+               krb5_free_context(ctx);
+       }
+
+       return realm;
+}
+
 
 /************************************************************************
  Routine to get the salting principal for this service.  This is 
@@ -391,25 +602,31 @@ krb5_principal kerberos_fetch_salt_princ_for_host_princ(krb5_context context,
  Setting principal to NULL deletes this entry.
  ************************************************************************/
 
-BOOL kerberos_secrets_store_salting_principal(const char *service,
+bool kerberos_secrets_store_salting_principal(const char *service,
                                              int enctype,
                                              const char *principal)
 {
        char *key = NULL;
-       BOOL ret = False;
+       bool ret = False;
        krb5_context context = NULL;
        krb5_principal princ = NULL;
        char *princ_s = NULL;
        char *unparsed_name = NULL;
+       krb5_error_code code;
 
-       krb5_init_context(&context);
-       if (!context) {
+       if (((code = krb5_init_context(&context)) != 0) || (context == NULL)) {
+               DEBUG(5, ("kerberos_secrets_store_salting_pricipal: kdb5_init_context failed: %s\n",
+                         error_message(code)));
                return False;
        }
        if (strchr_m(service, '@')) {
-               asprintf(&princ_s, "%s", service);
+               if (asprintf(&princ_s, "%s", service) == -1) {
+                       goto out;
+               }
        } else {
-               asprintf(&princ_s, "%s@%s", service, lp_realm());
+               if (asprintf(&princ_s, "%s@%s", service, lp_realm()) == -1) {
+                       goto out;
+               }
        }
 
        if (smb_krb5_parse_name(context, princ_s, &princ) != 0) {
@@ -420,8 +637,9 @@ BOOL kerberos_secrets_store_salting_principal(const char *service,
                goto out;
        }
 
-       asprintf(&key, "%s/%s/enctype=%d", SECRETS_SALTING_PRINCIPAL, unparsed_name, enctype);
-       if (!key)  {
+       if (asprintf(&key, "%s/%s/enctype=%d",
+                    SECRETS_SALTING_PRINCIPAL, unparsed_name, enctype)
+           == -1) {
                goto out;
        }
 
@@ -437,6 +655,10 @@ BOOL kerberos_secrets_store_salting_principal(const char *service,
        SAFE_FREE(princ_s);
        SAFE_FREE(unparsed_name);
 
+       if (princ) {
+               krb5_free_principal(context, princ);
+       }
+
        if (context) {
                krb5_free_context(context);
        }
@@ -461,45 +683,151 @@ int kerberos_kinit_password(const char *principal,
                                           cache_name,
                                           False,
                                           False,
-                                          0);
+                                          0,
+                                          NULL);
+}
+
+/************************************************************************
+************************************************************************/
+
+static char *print_kdc_line(char *mem_ctx,
+                       const char *prev_line,
+                       const struct sockaddr_storage *pss)
+{
+       char *kdc_str = NULL;
+
+       if (pss->ss_family == AF_INET) {
+               kdc_str = talloc_asprintf(mem_ctx, "%s\tkdc = %s\n",
+                                       prev_line,
+                                        print_canonical_sockaddr(mem_ctx, pss));
+       } else {
+               char addr[INET6_ADDRSTRLEN];
+               uint16_t port = get_sockaddr_port(pss);
+
+               if (port != 0 && port != DEFAULT_KRB5_PORT) {
+                       /* Currently for IPv6 we can't specify a non-default
+                          krb5 port with an address, as this requires a ':'.
+                          Resolve to a name. */
+                       char hostname[MAX_DNS_NAME_LENGTH];
+                       int ret = sys_getnameinfo((const struct sockaddr *)pss,
+                                       sizeof(*pss),
+                                       hostname, sizeof(hostname),
+                                       NULL, 0,
+                                       NI_NAMEREQD);
+                       if (ret) {
+                               DEBUG(0,("print_kdc_line: can't resolve name "
+                                       "for kdc with non-default port %s. "
+                                       "Error %s\n.",
+                                       print_canonical_sockaddr(mem_ctx, pss),
+                                       gai_strerror(ret)));
+                       }
+                       /* Success, use host:port */
+                       kdc_str = talloc_asprintf(mem_ctx,
+                                       "%s\tkdc = %s:%u\n",
+                                       prev_line,
+                                       hostname,
+                                       (unsigned int)port);
+               } else {
+                       kdc_str = talloc_asprintf(mem_ctx, "%s\tkdc = %s\n",
+                                       prev_line,
+                                       print_sockaddr(addr,
+                                               sizeof(addr),
+                                               pss));
+               }
+       }
+       return kdc_str;
 }
 
 /************************************************************************
  Create a string list of available kdc's, possibly searching by sitename.
  Does DNS queries.
+
+ If "sitename" is given, the DC's in that site are listed first.
+
 ************************************************************************/
 
-static char *get_kdc_ip_string(char *mem_ctx, const char *realm, struct in_addr primary_ip)
+static char *get_kdc_ip_string(char *mem_ctx,
+               const char *realm,
+               const char *sitename,
+               struct sockaddr_storage *pss)
 {
-       struct ip_service *ip_srv;
-       int count, i;
-       char *kdc_str = talloc_asprintf(mem_ctx, "\tkdc = %s\n",
-                                       inet_ntoa(primary_ip));
+       int i;
+       struct ip_service *ip_srv_site = NULL;
+       struct ip_service *ip_srv_nonsite = NULL;
+       int count_site = 0;
+       int count_nonsite;
+       char *kdc_str = print_kdc_line(mem_ctx, "", pss);
 
        if (kdc_str == NULL) {
                return NULL;
        }
 
-       if (!NT_STATUS_IS_OK(get_kdc_list(realm, &ip_srv, &count))) {
-               DEBUG(10,("get_kdc_ip_string: get_kdc_list failed. Returning %s\n",
-                       kdc_str ));
-               return kdc_str;
+       /*
+        * First get the KDC's only in this site, the rest will be
+        * appended later
+        */
+
+       if (sitename) {
+
+               get_kdc_list(realm, sitename, &ip_srv_site, &count_site);
+
+               for (i = 0; i < count_site; i++) {
+                       if (sockaddr_equal((struct sockaddr *)&ip_srv_site[i].ss,
+                                                  (struct sockaddr *)pss)) {
+                               continue;
+                       }
+                       /* Append to the string - inefficient
+                        * but not done often. */
+                       kdc_str = print_kdc_line(mem_ctx,
+                                               kdc_str,
+                                               &ip_srv_site[i].ss);
+                       if (!kdc_str) {
+                               SAFE_FREE(ip_srv_site);
+                               return NULL;
+                       }
+               }
        }
 
-       for (i = 0; i < count; i++) {
-               if (ip_equal(ip_srv[i].ip, primary_ip)) {
+       /* Get all KDC's. */
+
+       get_kdc_list(realm, NULL, &ip_srv_nonsite, &count_nonsite);
+
+       for (i = 0; i < count_nonsite; i++) {
+               int j;
+
+               if (sockaddr_equal((struct sockaddr *)&ip_srv_nonsite[i].ss, (struct sockaddr *)pss)) {
                        continue;
                }
+
+               /* Ensure this isn't an IP already seen (YUK! this is n*n....) */
+               for (j = 0; j < count_site; j++) {
+                       if (sockaddr_equal((struct sockaddr *)&ip_srv_nonsite[i].ss,
+                                               (struct sockaddr *)&ip_srv_site[j].ss)) {
+                               break;
+                       }
+                       /* As the lists are sorted we can break early if nonsite > site. */
+                       if (ip_service_compare(&ip_srv_nonsite[i], &ip_srv_site[j]) > 0) {
+                               break;
+                       }
+               }
+               if (j != i) {
+                       continue;
+               }
+
                /* Append to the string - inefficient but not done often. */
-               kdc_str = talloc_asprintf(mem_ctx, "%s\tkdc = %s\n",
-                       kdc_str, inet_ntoa(ip_srv[i].ip));
+               kdc_str = print_kdc_line(mem_ctx,
+                               kdc_str,
+                               &ip_srv_nonsite[i].ss);
                if (!kdc_str) {
-                       SAFE_FREE(ip_srv);
+                       SAFE_FREE(ip_srv_site);
+                       SAFE_FREE(ip_srv_nonsite);
                        return NULL;
                }
        }
 
-       SAFE_FREE(ip_srv);
+
+       SAFE_FREE(ip_srv_site);
+       SAFE_FREE(ip_srv_nonsite);
 
        DEBUG(10,("get_kdc_ip_string: Returning %s\n",
                kdc_str ));
@@ -514,17 +842,20 @@ static char *get_kdc_ip_string(char *mem_ctx, const char *realm, struct in_addr
  run as root or will fail (which is a good thing :-).
 ************************************************************************/
 
-BOOL create_local_private_krb5_conf_for_domain(const char *realm, const char *domain, struct in_addr ip)
+bool create_local_private_krb5_conf_for_domain(const char *realm,
+                                               const char *domain,
+                                               const char *sitename,
+                                               struct sockaddr_storage *pss)
 {
-       XFILE *xfp = NULL;
        char *dname = talloc_asprintf(NULL, "%s/smb_krb5", lp_lockdir());
+       char *tmpname = NULL;
        char *fname = NULL;
        char *file_contents = NULL;
-       char *kdc_ip_string;
+       char *kdc_ip_string = NULL;
        size_t flen = 0;
-       size_t ret;
+       ssize_t ret;
+       int fd;
        char *realm_upper = NULL;
-       int loopcount = 0;
 
        if (!dname) {
                return False;
@@ -537,6 +868,12 @@ BOOL create_local_private_krb5_conf_for_domain(const char *realm, const char *do
                return False;
        }
 
+       tmpname = talloc_asprintf(dname, "%s/smb_tmp_krb5.XXXXXX", lp_lockdir());
+       if (!tmpname) {
+               TALLOC_FREE(dname);
+               return False;
+       }
+
        fname = talloc_asprintf(dname, "%s/krb5.conf.%s", dname, domain);
        if (!fname) {
                TALLOC_FREE(dname);
@@ -549,16 +886,20 @@ BOOL create_local_private_krb5_conf_for_domain(const char *realm, const char *do
        realm_upper = talloc_strdup(fname, realm);
        strupper_m(realm_upper);
 
-       kdc_ip_string = get_kdc_ip_string(dname, realm, ip);
+       kdc_ip_string = get_kdc_ip_string(dname, realm, sitename, pss);
        if (!kdc_ip_string) {
                TALLOC_FREE(dname);
                return False;
        }
-               
-       file_contents = talloc_asprintf(fname, "[libdefaults]\n\tdefault_realm = %s\n\n"
-                               "[realms]\n\t%s = {\n"
-                               "\t\t%s\t}\n",
-                               realm_upper, realm_upper, kdc_ip_string);
+
+       file_contents = talloc_asprintf(fname,
+                                       "[libdefaults]\n\tdefault_realm = %s\n"
+                                       "\tdefault_tgs_enctypes = RC4-HMAC DES-CBC-CRC DES-CBC-MD5\n"
+                                       "\tdefault_tkt_enctypes = RC4-HMAC DES-CBC-CRC DES-CBC-MD5\n"
+                                       "\tpreferred_enctypes = RC4-HMAC DES-CBC-CRC DES-CBC-MD5\n\n"
+                                       "[realms]\n\t%s = {\n"
+                                       "\t%s\t}\n",
+                                       realm_upper, realm_upper, kdc_ip_string);
 
        if (!file_contents) {
                TALLOC_FREE(dname);
@@ -567,62 +908,111 @@ BOOL create_local_private_krb5_conf_for_domain(const char *realm, const char *do
 
        flen = strlen(file_contents);
 
-       while (loopcount < 10) {
-               SMB_STRUCT_STAT st;
-
-               xfp = x_fopen(fname, O_CREAT|O_WRONLY, 0644);
-               if (!xfp) {
-                       TALLOC_FREE(dname);
-                       return False;
-               }
-               /* Lock the file. */
-               if (!fcntl_lock(xfp->fd, F_SETLKW, 0, 1, F_WRLCK)) {
-                       unlink(fname);
-                       x_fclose(xfp);
-                       TALLOC_FREE(dname);
-                       return False;
-               }
+       fd = smb_mkstemp(tmpname);
+       if (fd == -1) {
+               DEBUG(0,("create_local_private_krb5_conf_for_domain: smb_mkstemp failed,"
+                       " for file %s. Errno %s\n",
+                       tmpname, strerror(errno) ));
+               TALLOC_FREE(dname);
+               return false;
+       }
 
-               /* We got the lock. Is the file still there ? */
-               if (sys_stat(fname,&st)==-1) {
-                       if (errno == ENOENT) {
-                               /* Nope - try again up to 10x */
-                               x_fclose(xfp);
-                               loopcount++;
-                               continue;       
-                       }
-                       unlink(fname);
-                       x_fclose(xfp);
-                       TALLOC_FREE(dname);
-                       return False;
-               }
-               break;
+       if (fchmod(fd, 0644)==-1) {
+               DEBUG(0,("create_local_private_krb5_conf_for_domain: fchmod failed for %s."
+                       " Errno %s\n",
+                       tmpname, strerror(errno) ));
+               unlink(tmpname);
+               close(fd);
+               TALLOC_FREE(dname);
+               return False;
        }
 
-       ret = x_fwrite(file_contents, 1, flen, xfp);
+       ret = write(fd, file_contents, flen);
        if (flen != ret) {
-               DEBUG(0,("create_local_private_krb5_conf_for_domain: x_fwrite failed,"
-                       " returned %u (should be %u). Errno %s\n",
-                       (unsigned int)ret, (unsigned int)flen, strerror(errno) ));
-               unlink(fname);
-               x_fclose(xfp);
+               DEBUG(0,("create_local_private_krb5_conf_for_domain: write failed,"
+                       " returned %d (should be %u). Errno %s\n",
+                       (int)ret, (unsigned int)flen, strerror(errno) ));
+               unlink(tmpname);
+               close(fd);
                TALLOC_FREE(dname);
                return False;
        }
-       if (x_fclose(xfp)==-1) {
-               DEBUG(0,("create_local_private_krb5_conf_for_domain: x_fclose failed."
+       if (close(fd)==-1) {
+               DEBUG(0,("create_local_private_krb5_conf_for_domain: close failed."
                        " Errno %s\n", strerror(errno) ));
-               unlink(fname);
+               unlink(tmpname);
+               TALLOC_FREE(dname);
+               return False;
+       }
+
+       if (rename(tmpname, fname) == -1) {
+               DEBUG(0,("create_local_private_krb5_conf_for_domain: rename "
+                       "of %s to %s failed. Errno %s\n",
+                       tmpname, fname, strerror(errno) ));
+               unlink(tmpname);
                TALLOC_FREE(dname);
                return False;
        }
 
        DEBUG(5,("create_local_private_krb5_conf_for_domain: wrote "
-               "file %s with realm %s KDC = %s\n",
-               fname, realm_upper, inet_ntoa(ip) ));
+               "file %s with realm %s KDC list = %s\n",
+               fname, realm_upper, kdc_ip_string));
 
        /* Set the environment variable to this file. */
        setenv("KRB5_CONFIG", fname, 1);
+
+#if defined(OVERWRITE_SYSTEM_KRB5_CONF)
+
+#define SYSTEM_KRB5_CONF_PATH "/etc/krb5.conf"
+       /* Insanity, sheer insanity..... */
+
+       if (strequal(realm, lp_realm())) {
+               char linkpath[PATH_MAX+1];
+               int lret;
+
+               lret = readlink(SYSTEM_KRB5_CONF_PATH, linkpath, sizeof(linkpath)-1);
+               if (lret != -1) {
+                       linkpath[lret] = '\0';
+               }
+
+               if (lret != -1 || strcmp(linkpath, fname) == 0) {
+                       /* Symlink already exists. */
+                       TALLOC_FREE(dname);
+                       return True;
+               }
+
+               /* Try and replace with a symlink. */
+               if (symlink(fname, SYSTEM_KRB5_CONF_PATH) == -1) {
+                       const char *newpath = SYSTEM_KRB5_CONF_PATH ## ".saved";
+                       if (errno != EEXIST) {
+                               DEBUG(0,("create_local_private_krb5_conf_for_domain: symlink "
+                                       "of %s to %s failed. Errno %s\n",
+                                       fname, SYSTEM_KRB5_CONF_PATH, strerror(errno) ));
+                               TALLOC_FREE(dname);
+                               return True; /* Not a fatal error. */
+                       }
+
+                       /* Yes, this is a race conditon... too bad. */
+                       if (rename(SYSTEM_KRB5_CONF_PATH, newpath) == -1) {
+                               DEBUG(0,("create_local_private_krb5_conf_for_domain: rename "
+                                       "of %s to %s failed. Errno %s\n",
+                                       SYSTEM_KRB5_CONF_PATH, newpath,
+                                       strerror(errno) ));
+                               TALLOC_FREE(dname);
+                               return True; /* Not a fatal error. */
+                       }
+
+                       if (symlink(fname, SYSTEM_KRB5_CONF_PATH) == -1) {
+                               DEBUG(0,("create_local_private_krb5_conf_for_domain: "
+                                       "forced symlink of %s to /etc/krb5.conf failed. Errno %s\n",
+                                       fname, strerror(errno) ));
+                               TALLOC_FREE(dname);
+                               return True; /* Not a fatal error. */
+                       }
+               }
+       }
+#endif
+
        TALLOC_FREE(dname);
 
        return True;