pam: add pam_gssapi_services option

:config: Added `pam_gssapi_services` to list PAM services
  that can authenticate using GSSAPI

Reviewed-by: Robbie Harwood <rharwood@redhat.com>
Reviewed-by: Sumit Bose <sbose@redhat.com>

src/confdb/confdb.c

@@ -1581,6 +1581,18 @@ static int confdb_get_domain_internal(struct confdb_ctx *cdb,
         }
     }
 
+    tmp = ldb_msg_find_attr_as_string(res->msgs[0], CONFDB_PAM_GSSAPI_SERVICES,
+                                      "-");
+    if (tmp != NULL) {
+        ret = split_on_separator(domain, tmp, ',', true, true,
+                                 &domain->gssapi_services, NULL);
+        if (ret != 0) {
+            DEBUG(SSSDBG_FATAL_FAILURE,
+                  "Cannot parse %s\n", CONFDB_PAM_GSSAPI_SERVICES);
+            goto done;
+        }
+    }
+
     domain->has_views = false;
     domain->view_name = NULL;
 

src/confdb/confdb.h

@@ -144,6 +144,7 @@
 #define CONFDB_PAM_P11_ALLOWED_SERVICES "pam_p11_allowed_services"
 #define CONFDB_PAM_P11_URI "p11_uri"
 #define CONFDB_PAM_INITGROUPS_SCHEME "pam_initgroups_scheme"
+#define CONFDB_PAM_GSSAPI_SERVICES "pam_gssapi_services"
 
 /* SUDO */
 #define CONFDB_SUDO_CONF_ENTRY "config/sudo"
@@ -431,6 +432,9 @@ struct sss_domain_info {
 
     /* Keytab used by this domain. */
     const char *krb5_keytab;
+
+    /* List of PAM services that are allowed to authenticate with GSSAPI. */
+    char **gssapi_services;
 };
 
 /**

src/config/SSSDConfig/sssdoptions.py

@@ -104,6 +104,7 @@ def __init__(self):
         'p11_wait_for_card_timeout': _('Additional timeout to wait for a card if requested'),
         'p11_uri': _('PKCS#11 URI to restrict the selection of devices for Smartcard authentication'),
         'pam_initgroups_scheme' : _('When shall the PAM responder force an initgroups request'),
+        'pam_gssapi_services' : _('List of PAM services that are allowed to authenticate with GSSAPI.'),
 
         # [sudo]
         'sudo_timed': _('Whether to evaluate the time-based attributes in sudo rules'),

src/config/SSSDConfigTest.py

@@ -653,7 +653,8 @@ def testListOptions(self):
             'full_name_format',
             're_expression',
             'cached_auth_timeout',
-            'auto_private_groups']
+            'auto_private_groups',
+            'pam_gssapi_services']
 
         self.assertTrue(type(options) == dict,
                         "Options should be a dictionary")
@@ -1030,7 +1031,8 @@ def testRemoveProvider(self):
             'full_name_format',
             're_expression',
             'cached_auth_timeout',
-            'auto_private_groups']
+            'auto_private_groups',
+            'pam_gssapi_services']
 
         self.assertTrue(type(options) == dict,
                         "Options should be a dictionary")

src/config/cfg_rules.ini

@@ -139,6 +139,7 @@ option = pam_p11_allowed_services
 option = p11_wait_for_card_timeout
 option = p11_uri
 option = pam_initgroups_scheme
+option = pam_gssapi_services
 
 [rule/allowed_sudo_options]
 validator = ini_allowed_options
@@ -437,6 +438,7 @@ option = wildcard_limit
 option = full_name_format
 option = re_expression
 option = auto_private_groups
+option = pam_gssapi_services
 
 #Entry cache timeouts
 option = entry_cache_user_timeout
@@ -831,6 +833,7 @@ option = ad_backup_server
 option = ad_site
 option = use_fully_qualified_names
 option = auto_private_groups
+option = pam_gssapi_services
 
 [rule/sssd_checks]
 validator = sssd_checks

src/config/etc/sssd.api.conf

@@ -80,6 +80,7 @@ pam_p11_allowed_services = str, None, false
 p11_wait_for_card_timeout = int, None, false
 p11_uri = str, None, false
 pam_initgroups_scheme = str, None, false
+pam_gssapi_services = str, None, false
 
 [sudo]
 # sudo service
@@ -199,6 +200,7 @@ cached_auth_timeout = int, None, false
 full_name_format = str, None, false
 re_expression = str, None, false
 auto_private_groups = str, None, false
+pam_gssapi_services = str, None, false
 
 #Entry cache timeouts
 entry_cache_user_timeout = int, None, false

src/db/sysdb_subdomains.c

@@ -184,6 +184,8 @@ struct sss_domain_info *new_subdomain(TALLOC_CTX *mem_ctx,
     dom->homedir_substr = parent->homedir_substr;
     dom->override_gid = parent->override_gid;
 
+    dom->gssapi_services = parent->gssapi_services;
+
     if (parent->sysdb == NULL) {
         DEBUG(SSSDBG_OP_FAILURE, "Missing sysdb context in parent domain.\n");
         goto fail;
@@ -241,6 +243,17 @@ check_subdom_config_file(struct confdb_ctx *confdb,
           sd_conf_path, CONFDB_DOMAIN_FQ,
           subdomain->fqnames ? "TRUE" : "FALSE");
 
+    /* allow to set pam_gssapi_services */
+    ret = confdb_get_string_as_list(confdb, subdomain, sd_conf_path,
+                                    CONFDB_PAM_GSSAPI_SERVICES,
+                                    &subdomain->gssapi_services);
+    if (ret != EOK && ret != ENOENT) {
+        DEBUG(SSSDBG_OP_FAILURE,
+              "Failed to get %s option for the subdomain: %s\n",
+              CONFDB_PAM_GSSAPI_SERVICES, subdomain->name);
+        goto done;
+    }
+
     ret = EOK;
 done:
     talloc_free(tmp_ctx);

src/man/sssd.conf.5.xml

@@ -1706,6 +1706,35 @@ p11_uri = library-description=OpenSC%20smartcard%20framework;slot-id=2
                         </para>
                     </listitem>
                 </varlistentry>
+                <varlistentry>
+                    <term>pam_gssapi_services</term>
+                    <listitem>
+                        <para>
+                            Comma separated list of PAM services that are
+                            allowed to try GSSAPI authentication using
+                            pam_sss_gss.so module.
+                        </para>
+                        <para>
+                            To disable GSSAPI authentication, set this option
+                            to <quote>-</quote> (dash).
+                        </para>
+                        <para>
+                            Note: This option can also be set per-domain which
+                            overwrites the value in [pam] section. It can also
+                            be set for trusted domain which overwrites the value
+                            in the domain section.
+                        </para>
+                        <para>
+                            Example:
+                            <programlisting>
+pam_gssapi_services = sudo, sudo-i
+                            </programlisting>
+                        </para>
+                        <para>
+                            Default: - (GSSAPI authentication is disabled)
+                        </para>
+                    </listitem>
+                </varlistentry>
             </variablelist>
         </refsect2>
 
@@ -3780,6 +3809,7 @@ ldap_user_extra_attrs = phone:telephoneNumber
             <para>ad_backup_server,</para>
             <para>ad_site,</para>
             <para>use_fully_qualified_names</para>
+            <para>pam_gssapi_services</para>
         <para>
             For more details about these options see their individual description
             in the manual page.

src/responder/pam/pamsrv.c

@@ -327,6 +327,27 @@ static int pam_process_init(TALLOC_CTX *mem_ctx,
         }
     }
 
+    ret = confdb_get_string(pctx->rctx->cdb, pctx, CONFDB_PAM_CONF_ENTRY,
+                            CONFDB_PAM_GSSAPI_SERVICES, "-", &tmpstr);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_FATAL_FAILURE,
+              "Failed to determine gssapi services.\n");
+        goto done;
+    }
+    DEBUG(SSSDBG_TRACE_INTERNAL, "Found value [%s] for option [%s].\n", tmpstr,
+                                 CONFDB_PAM_GSSAPI_SERVICES);
+
+    if (tmpstr != NULL) {
+        ret = split_on_separator(pctx, tmpstr, ',', true, true,
+                                 &pctx->gssapi_services, NULL);
+        if (ret != EOK) {
+            DEBUG(SSSDBG_MINOR_FAILURE,
+                  "split_on_separator() failed [%d]: [%s].\n", ret,
+                  sss_strerror(ret));
+            goto done;
+        }
+    }
+
     /* The responder is initialized. Now tell it to the monitor. */
     ret = sss_monitor_service_init(rctx, rctx->ev, SSS_BUS_PAM,
                                    SSS_PAM_SBUS_SERVICE_NAME,

src/responder/pam/pamsrv.h

@@ -62,6 +62,9 @@ struct pam_ctx {
     int num_prompting_config_sections;
 
     enum pam_initgroups_scheme initgroups_scheme;
+
+    /* List of PAM services that are allowed to authenticate with GSSAPI. */
+    char **gssapi_services;
 };
 
 struct pam_auth_req {