IFP: use a list of allowed_uids for authentication

Similar to the PAC responder, the InfoPipe uses a list of UIDs that are
allowed to communicate with the IFP responder.

Reviewed-by: Pavel Březina <pbrezina@redhat.com>
Reviewed-by: Stef Walter <stefw@redhat.com>
(cherry picked from commit 3660f49f81e4db07be66fe0887af9d62065f1f2c)

9 files changed, 159 insertions, 6 deletions

diff --git a/src/config/SSSDConfig/__init__.py.in b/src/config/SSSDConfig/__init__.py.in
index de0348b1d..7070b88a1 100644
--- a/src/config/SSSDConfig/__init__.py.in
+++ b/src/config/SSSDConfig/__init__.py.in
@@ -94,6 +94,9 @@ option_strings = {
     # [pac]
     'allowed_uids': _('List of UIDs or user names allowed to access the PAC responder'),
 
+    # [ifp]
+    'allowed_uids': _('List of UIDs or user names allowed to access the InfoPipe responder'),
+
     # [provider]
     'id_provider' : _('Identity provider'),
     'auth_provider' : _('Authentication provider'),
diff --git a/src/config/SSSDConfigTest.py b/src/config/SSSDConfigTest.py
index a539b805f..6e8af1dab 100755
--- a/src/config/SSSDConfigTest.py
+++ b/src/config/SSSDConfigTest.py
@@ -1234,7 +1234,8 @@ class SSSDConfigTestSSSDConfig(unittest.TestCase):
             'sudo',
             'autofs',
             'ssh',
-            'pac']
+            'pac',
+            'ifp']
         for section in control_list:
             self.assertTrue(sssdconfig.has_section(section),
                             "Section [%s] missing" %
@@ -1327,7 +1328,8 @@ class SSSDConfigTestSSSDConfig(unittest.TestCase):
             'sudo',
             'autofs',
             'ssh',
-            'pac']
+            'pac',
+            'ifp']
         service_list = sssdconfig.list_services()
         for service in control_list:
             self.assertTrue(service in service_list,
diff --git a/src/config/etc/sssd.api.conf b/src/config/etc/sssd.api.conf
index 9805dddfe..d6f2d6b45 100644
--- a/src/config/etc/sssd.api.conf
+++ b/src/config/etc/sssd.api.conf
@@ -72,6 +72,10 @@ ssh_known_hosts_timeout = int, None, false
 # PAC responder
 allowed_uids = str, None, false
 
+[ifp]
+# InfoPipe responder
+allowed_uids = str, None, false
+
 [provider]
 #Available provider types
 id_provider = str, None, true
diff --git a/src/man/sssd-ifp.5.xml b/src/man/sssd-ifp.5.xml
index dfac25298..7e2ea7cfc 100644
--- a/src/man/sssd-ifp.5.xml
+++ b/src/man/sssd-ifp.5.xml
@@ -40,6 +40,38 @@
         </para>
     </refsect1>
 
+    <refsect1 id='configuration-options'>
+        <title>CONFIGURATION OPTIONS</title>
+            <para>
+                These options can be used to configure the InfoPipe responder.
+            </para>
+            <variablelist>
+                <varlistentry>
+                    <term>allowed_uids (string)</term>
+                    <listitem>
+                        <para>
+                            Specifies the comma-separated list of UID values or
+                            user names that are allowed to access the InfoPipe
+                            responder. User names are resolved to UIDs at
+                            startup.
+                        </para>
+                        <para>
+                            Default: 0 (only the root user is allowed to access
+                            the InfoPipe responder)
+                        </para>
+                        <para>
+                            Please note that although the UID 0 is used as the
+                            default it will be overwritten with this option. If
+                            you still want to allow the root user to access the
+                            InfoPipe responder, which would be the typical
+                            case, you have to add 0 to the list of allowed UIDs
+                            as well.
+                        </para>
+                    </listitem>
+                </varlistentry>
+            </variablelist>
+    </refsect1>
+
     <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="include/seealso.xml" />
 
 </refentry>
diff --git a/src/responder/ifp/ifp_private.h b/src/responder/ifp/ifp_private.h
index 472d10441..bc476291a 100644
--- a/src/responder/ifp/ifp_private.h
+++ b/src/responder/ifp/ifp_private.h
@@ -56,6 +56,9 @@ errno_t ifp_req_create(struct sbus_request *dbus_req,
                        struct ifp_ctx *ifp_ctx,
                        struct ifp_req **_ifp_req);
 
+/* Returns an appropriate DBus error for specific ifp_req_create failures */
+int ifp_req_create_handle_failure(struct sbus_request *dbus_req, errno_t err);
+
 const char *ifp_path_strip_prefix(const char *path, const char *prefix);
 errno_t ifp_add_ldb_el_to_dict(DBusMessageIter *iter_dict,
                                struct ldb_message_element *el);
diff --git a/src/responder/ifp/ifpsrv.c b/src/responder/ifp/ifpsrv.c
index 2f98cf838..65613b941 100644
--- a/src/responder/ifp/ifpsrv.c
+++ b/src/responder/ifp/ifpsrv.c
@@ -40,6 +40,8 @@
 #include "responder/ifp/ifp_private.h"
 #include "responder/common/responder_sbus.h"
 
+#define DEFAULT_ALLOWED_UIDS "0"
+
 struct mon_cli_iface monitor_ifp_methods = {
     { &mon_cli_iface_meta, 0 },
     .ping = monitor_common_pong,
@@ -201,6 +203,7 @@ int ifp_process_init(TALLOC_CTX *mem_ctx,
     struct be_conn *iter;
     int ret;
     int max_retries;
+    char *uid_str;
 
     ifp_cmds = get_ifp_cmds();
     ret = sss_process_init(mem_ctx, ev, cdb,
@@ -236,6 +239,23 @@ int ifp_process_init(TALLOC_CTX *mem_ctx,
         goto fail;
     }
 
+    ret = confdb_get_string(ifp_ctx->rctx->cdb, ifp_ctx->rctx,
+                            CONFDB_IFP_CONF_ENTRY, CONFDB_SERVICE_ALLOWED_UIDS,
+                            DEFAULT_ALLOWED_UIDS, &uid_str);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_FATAL_FAILURE, ("Failed to get allowed UIDs.\n"));
+        goto fail;
+    }
+
+    ret = csv_string_to_uid_array(ifp_ctx->rctx, uid_str, true,
+                                  &ifp_ctx->rctx->allowed_uids_count,
+                                  &ifp_ctx->rctx->allowed_uids);
+    talloc_free(uid_str);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_FATAL_FAILURE, ("Failed to set allowed UIDs.\n"));
+        goto fail;
+    }
+
     /* Enable automatic reconnection to the Data Provider */
     ret = confdb_get_int(ifp_ctx->rctx->cdb,
                          CONFDB_IFP_CONF_ENTRY,
diff --git a/src/responder/ifp/ifpsrv_cmd.c b/src/responder/ifp/ifpsrv_cmd.c
index 4f73342dd..e26bcfa58 100644
--- a/src/responder/ifp/ifpsrv_cmd.c
+++ b/src/responder/ifp/ifpsrv_cmd.c
@@ -39,12 +39,18 @@ int ifp_ping(struct sbus_request *dbus_req, void *data)
     static const char *pong = "PONG";
     const char *request;
     DBusError dberr;
+    errno_t ret;
+    struct ifp_req *ifp_req;
 
     if (ifp_ctx == NULL) {
         DEBUG(SSSDBG_CRIT_FAILURE, "Invalid pointer!\n");
         return sbus_request_return_and_finish(dbus_req, DBUS_TYPE_INVALID);
     }
 
+    ret = ifp_req_create(dbus_req, ifp_ctx, &ifp_req);
+    if (ret != EOK) {
+        return ifp_req_create_handle_failure(dbus_req, ret);
+    }
 
     if (!sbus_request_parse_or_finish(dbus_req,
                                       DBUS_TYPE_STRING, &request,
diff --git a/src/responder/ifp/ifpsrv_util.c b/src/responder/ifp/ifpsrv_util.c
index e16d36279..2bce20186 100644
--- a/src/responder/ifp/ifpsrv_util.c
+++ b/src/responder/ifp/ifpsrv_util.c
@@ -29,6 +29,7 @@ errno_t ifp_req_create(struct sbus_request *dbus_req,
                        struct ifp_req **_ifp_req)
 {
     struct ifp_req *ireq = NULL;
+    errno_t ret;
 
     if (ifp_ctx->sysbus == NULL) {
         DEBUG(SSSDBG_CRIT_FAILURE, "Responder not connected to sysbus!\n");
@@ -43,8 +44,52 @@ errno_t ifp_req_create(struct sbus_request *dbus_req,
     ireq->ifp_ctx = ifp_ctx;
     ireq->dbus_req = dbus_req;
 
+    if (dbus_req->client == -1) {
+        /* We got a sysbus message but couldn't identify the
+         * caller? Bail out! */
+        DEBUG(SSSDBG_CRIT_FAILURE,
+              "BUG: Received a message without a known caller!\n");
+        ret = EACCES;
+        goto done;
+    }
+
+    ret = check_allowed_uids(dbus_req->client,
+                             ifp_ctx->rctx->allowed_uids_count,
+                             ifp_ctx->rctx->allowed_uids);
+    if (ret == EACCES) {
+        DEBUG(SSSDBG_MINOR_FAILURE,
+              "User %"PRIi64" not in ACL\n", dbus_req->client);
+        goto done;
+    } else if (ret != EOK) {
+        DEBUG(SSSDBG_OP_FAILURE,
+              "Cannot check if user %"PRIi64" is present in ACL\n",
+              dbus_req->client);
+        goto done;
+    }
+
     *_ifp_req = ireq;
-    return EOK;
+    ret = EOK;
+done:
+    if (ret != EOK) {
+        talloc_free(ireq);
+    }
+    return ret;
+}
+
+int ifp_req_create_handle_failure(struct sbus_request *dbus_req, errno_t err)
+{
+    if (err == EACCES) {
+        return sbus_request_fail_and_finish(dbus_req,
+                               sbus_error_new(dbus_req,
+                                              DBUS_ERROR_ACCESS_DENIED,
+                                              "User %"PRIi64" not in ACL\n",
+                                              dbus_req->client));
+    }
+
+    return sbus_request_fail_and_finish(dbus_req,
+                                        sbus_error_new(dbus_req,
+                                            DBUS_ERROR_FAILED,
+                                            "Cannot create IFP request\n"));
 }
 
 const char *ifp_path_strip_prefix(const char *path, const char *prefix)
diff --git a/src/tests/cmocka/test_ifp.c b/src/tests/cmocka/test_ifp.c
index 161f8ffe4..188508bcb 100644
--- a/src/tests/cmocka/test_ifp.c
+++ b/src/tests/cmocka/test_ifp.c
@@ -24,6 +24,7 @@
 
 #include "db/sysdb.h"
 #include "tests/cmocka/common_mock.h"
+#include "tests/cmocka/common_mock_resp.h"
 #include "responder/ifp/ifp_private.h"
 #include "sbus/sssd_dbus_private.h"
 
@@ -35,6 +36,14 @@ mock_ifp_ctx(TALLOC_CTX *mem_ctx)
     ifp_ctx = talloc_zero(mem_ctx, struct ifp_ctx);
     assert_non_null(ifp_ctx);
 
+    ifp_ctx->rctx = mock_rctx(ifp_ctx, NULL, NULL, NULL);
+    assert_non_null(ifp_ctx->rctx);
+
+    ifp_ctx->rctx->allowed_uids = talloc_array(ifp_ctx->rctx, uint32_t, 1);
+    assert_non_null(ifp_ctx->rctx->allowed_uids);
+    ifp_ctx->rctx->allowed_uids[0] = geteuid();
+    ifp_ctx->rctx->allowed_uids_count = 1;
+
     ifp_ctx->sysbus = talloc_zero(ifp_ctx, struct sysbus_ctx);
     assert_non_null(ifp_ctx->sysbus);
 
@@ -45,7 +54,7 @@ mock_ifp_ctx(TALLOC_CTX *mem_ctx)
 }
 
 static struct sbus_request *
-mock_sbus_request(TALLOC_CTX *mem_ctx)
+mock_sbus_request(TALLOC_CTX *mem_ctx, uid_t client)
 {
     struct sbus_request *sr;
 
@@ -59,6 +68,8 @@ mock_sbus_request(TALLOC_CTX *mem_ctx)
     assert_non_null(sr->message);
     dbus_message_set_serial(sr->message, 1);
 
+    sr->client = client;
+
     return sr;
 }
 
@@ -75,7 +86,7 @@ void ifp_test_req_create(void **state)
     assert_non_null(ifp_ctx);
     check_leaks_push(ifp_ctx);
 
-    sr = mock_sbus_request(ifp_ctx);
+    sr = mock_sbus_request(ifp_ctx, geteuid());
     assert_non_null(sr);
     check_leaks_push(sr);
 
@@ -92,6 +103,32 @@ void ifp_test_req_create(void **state)
     assert_true(leak_check_teardown());
 }
 
+void ifp_test_req_wrong_uid(void **state)
+{
+    struct ifp_req *ireq;
+    struct sbus_request *sr;
+    struct ifp_ctx *ifp_ctx;
+    errno_t ret;
+
+    assert_true(leak_check_setup());
+
+    ifp_ctx = mock_ifp_ctx(global_talloc_context);
+    assert_non_null(ifp_ctx);
+    check_leaks_push(ifp_ctx);
+
+    sr = mock_sbus_request(ifp_ctx, geteuid()+1);
+    assert_non_null(sr);
+
+    ret = ifp_req_create(sr, ifp_ctx, &ireq);
+    assert_int_equal(ret, EACCES);
+    talloc_free(sr);
+
+    assert_true(check_leaks_pop(ifp_ctx) == true);
+    talloc_free(ifp_ctx);
+
+    assert_true(leak_check_teardown());
+}
+
 void test_path_prefix(void **state)
 {
     const char *prefix = "foo";
@@ -111,7 +148,7 @@ void test_el_to_dict(void **state)
     char *attr_name;
     char *attr_val;
 
-    sr = mock_sbus_request(global_talloc_context);
+    sr = mock_sbus_request(global_talloc_context, geteuid());
     assert_non_null(sr);
 
     el = talloc(sr, struct ldb_message_element);
@@ -181,6 +218,7 @@ int main(int argc, const char *argv[])
 
     const UnitTest tests[] = {
         unit_test(ifp_test_req_create),
+        unit_test(ifp_test_req_wrong_uid),
         unit_test(test_path_prefix),
         unit_test(test_el_to_dict),
     };