Add infrastructure to run bits of tests under an alternative uid

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=88810
Reviewed-by: Philip Withnall

4 files changed, 142 insertions, 11 deletions

diff --git a/test/dbus-daemon-eavesdrop.c b/test/dbus-daemon-eavesdrop.c
index 79c1e903..686ccb35 100644
--- a/test/dbus-daemon-eavesdrop.c
+++ b/test/dbus-daemon-eavesdrop.c
@@ -283,7 +283,7 @@ setup (Fixture *f,
   f->ge = NULL;
   dbus_error_init (&f->e);
 
-  address = test_get_dbus_daemon (NULL, &f->daemon_pid);
+  address = test_get_dbus_daemon (NULL, TEST_USER_ME, &f->daemon_pid);
 
   f->sender = test_connect_to_bus (f->ctx, address);
   dbus_bus_request_name (f->sender, SENDER_NAME, DBUS_NAME_FLAG_DO_NOT_QUEUE,
diff --git a/test/dbus-daemon.c b/test/dbus-daemon.c
index 02684646..02590904 100644
--- a/test/dbus-daemon.c
+++ b/test/dbus-daemon.c
@@ -124,6 +124,7 @@ setup (Fixture *f,
   dbus_error_init (&f->e);
 
   address = test_get_dbus_daemon (config ? config->config_file : NULL,
+                                  TEST_USER_ME,
                                   &f->daemon_pid);
 
   if (address == NULL)
diff --git a/test/test-utils-glib.c b/test/test-utils-glib.c
index ce312f54..24f0ee46 100644
--- a/test/test-utils-glib.c
+++ b/test/test-utils-glib.c
@@ -33,9 +33,11 @@
 # include <io.h>
 # include <windows.h>
 #else
+# include <errno.h>
 # include <signal.h>
 # include <unistd.h>
 # include <sys/types.h>
+# include <pwd.h>
 #endif
 
 #include <glib.h>
@@ -53,9 +55,41 @@ _test_assert_no_error (const DBusError *e,
         file, line, e->name, e->message);
 }
 
+#ifdef DBUS_UNIX
+static void
+child_setup (gpointer user_data)
+{
+  const struct passwd *pwd = user_data;
+  uid_t uid = geteuid ();
+
+  if (pwd == NULL || (pwd->pw_uid == uid && getuid () == uid))
+    return;
+
+  if (uid != 0)
+    g_error ("not currently euid 0: %lu", (unsigned long) uid);
+
+  if (setuid (pwd->pw_uid) != 0)
+    g_error ("could not setuid (%lu): %s",
+        (unsigned long) pwd->pw_uid, g_strerror (errno));
+
+  uid = getuid ();
+
+  if (uid != pwd->pw_uid)
+    g_error ("after successful setuid (%lu) my uid is %ld",
+        (unsigned long) pwd->pw_uid, (unsigned long) uid);
+
+  uid = geteuid ();
+
+  if (uid != pwd->pw_uid)
+    g_error ("after successful setuid (%lu) my euid is %ld",
+        (unsigned long) pwd->pw_uid, (unsigned long) uid);
+}
+#endif
+
 static gchar *
 spawn_dbus_daemon (const gchar *binary,
     const gchar *configuration,
+    TestUser user,
     GPid *daemon_pid)
 {
   GError *error = NULL;
@@ -68,13 +102,74 @@ spawn_dbus_daemon (const gchar *binary,
       "--print-address=1", /* stdout */
       NULL
   };
+#ifdef DBUS_UNIX
+  const struct passwd *pwd = NULL;
+#endif
+
+  if (user == TEST_USER_ME)
+    {
+#ifdef DBUS_UNIX
+      if (getuid () == 0)
+        {
+          g_message ("SKIP: this test is not designed to run as root");
+          return NULL;
+        }
+#endif
+    }
+  else
+    {
+#ifdef DBUS_UNIX
+      if (getuid () != 0)
+        {
+          g_message ("SKIP: cannot use alternative uid when not uid 0");
+          return NULL;
+        }
+
+      switch (user)
+        {
+          case TEST_USER_ROOT:
+            break;
+
+          case TEST_USER_MESSAGEBUS:
+            pwd = getpwnam (DBUS_USER);
+
+            if (pwd == NULL)
+              {
+                g_message ("SKIP: user '%s' does not exist", DBUS_USER);
+                return NULL;
+              }
+
+            break;
+
+          case TEST_USER_OTHER:
+            pwd = getpwnam (DBUS_TEST_USER);
+
+            if (pwd == NULL)
+              {
+                g_message ("SKIP: user '%s' does not exist", DBUS_TEST_USER);
+                return NULL;
+              }
+
+            break;
+
+          default:
+            g_assert_not_reached ();
+        }
+#else
+      g_message ("SKIP: cannot use alternative uid on Windows");
+      return NULL;
+#endif
+    }
 
   g_spawn_async_with_pipes (NULL, /* working directory */
       (gchar **) argv, /* g_s_a_w_p() is not const-correct :-( */
       NULL, /* envp */
       G_SPAWN_DO_NOT_REAP_CHILD | G_SPAWN_SEARCH_PATH,
-      NULL, /* child_setup */
-      NULL, /* user data */
+#ifdef DBUS_UNIX
+      child_setup, (gpointer) pwd,
+#else
+      NULL, NULL,
+#endif
       daemon_pid,
       NULL, /* child's stdin = /dev/null */
       &address_fd,
@@ -118,6 +213,7 @@ spawn_dbus_daemon (const gchar *binary,
 
 gchar *
 test_get_dbus_daemon (const gchar *config_file,
+                      TestUser     user,
                       GPid        *daemon_pid)
 {
   gchar *dbus_daemon;
@@ -126,12 +222,6 @@ test_get_dbus_daemon (const gchar *config_file,
 
   if (config_file != NULL)
     {
-      if (g_getenv ("DBUS_TEST_DAEMON_ADDRESS") != NULL)
-        {
-          g_message ("SKIP: cannot use DBUS_TEST_DAEMON_ADDRESS for "
-              "unusally-configured dbus-daemon");
-          return NULL;
-        }
 
       if (g_getenv ("DBUS_TEST_DATA") == NULL)
         {
@@ -167,11 +257,20 @@ test_get_dbus_daemon (const gchar *config_file,
 
   if (g_getenv ("DBUS_TEST_DAEMON_ADDRESS") != NULL)
     {
-      address = g_strdup (g_getenv ("DBUS_TEST_DAEMON_ADDRESS"));
+      if (config_file != NULL || user != TEST_USER_ME)
+        {
+          g_message ("SKIP: cannot use DBUS_TEST_DAEMON_ADDRESS for "
+              "unusally-configured dbus-daemon");
+          address = NULL;
+        }
+      else
+        {
+          address = g_strdup (g_getenv ("DBUS_TEST_DAEMON_ADDRESS"));
+        }
     }
   else
     {
-      address = spawn_dbus_daemon (dbus_daemon, arg, daemon_pid);
+      address = spawn_dbus_daemon (dbus_daemon, arg, user, daemon_pid);
     }
 
   g_free (dbus_daemon);
diff --git a/test/test-utils-glib.h b/test/test-utils-glib.h
index b233384f..c672fe50 100644
--- a/test/test-utils-glib.h
+++ b/test/test-utils-glib.h
@@ -33,12 +33,43 @@
 
 #include "test-utils.h"
 
+/*
+ * Multi-user support for regression tests run with root privileges in
+ * a continuous integration system.
+ *
+ * A developer would normally run the tests as their own uid. Tests run
+ * as TEST_USER_ME are run, and the others are skipped.
+ *
+ * In a CI system that has access to root privileges, most tests should still
+ * be run as an arbitrary non-root user, as above.
+ *
+ * Certain tests can usefully be run again, as root. When this is done,
+ * tests using TEST_USER_ME will be skipped, and tests using TEST_USER_ROOT,
+ * TEST_USER_MESSAGEBUS and/or TEST_USER_OTHER can exercise situations
+ * that only arise when there's more than one uid.
+ */
+typedef enum {
+    /* Whatever non-root user happens to be running the regression test;
+     * such tests also work on Windows */
+    TEST_USER_ME,
+    /* Must be uid 0 on Unix; the test is skipped on Windows */
+    TEST_USER_ROOT,
+    /* The user who would normally run the system bus. This is the DBUS_USER
+     * from configure.ac, usually 'messagebus' but perhaps 'dbus' or
+     * '_dbus'. */
+    TEST_USER_MESSAGEBUS,
+    /* An unprivileged user who is neither root nor DBUS_USER.
+     * This is DBUS_TEST_USER from configure.ac, usually 'nobody'. */
+    TEST_USER_OTHER
+} TestUser;
+
 #define test_assert_no_error(e) _test_assert_no_error (e, __FILE__, __LINE__)
 void _test_assert_no_error (const DBusError *e,
     const char *file,
     int line);
 
 gchar *test_get_dbus_daemon (const gchar *config_file,
+    TestUser user,
     GPid *daemon_pid);
 
 DBusConnection *test_connect_to_bus (TestMainContext *ctx,