Add xdg-app enter command

This lets you enter a sandbox and run a command there, which is useful
for debugging purposes.

app/Makefile.am.inc

@@ -16,6 +16,7 @@ xdg_app_SOURCES = \
 	app/xdg-app-builtins-uninstall.c \
 	app/xdg-app-builtins-list.c \
 	app/xdg-app-builtins-run.c \
+	app/xdg-app-builtins-enter.c \
 	app/xdg-app-builtins-build-init.c \
 	app/xdg-app-builtins-build.c \
 	app/xdg-app-builtins-build-finish.c \

app/xdg-app-builtins-enter.c

@@ -0,0 +1,288 @@
+/*
+ * Copyright © 2014 Red Hat, Inc
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors:
+ *       Alexander Larsson <alexl@redhat.com>
+ */
+
+#include "config.h"
+
+#include <locale.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+
+#include "libgsystem.h"
+#include "libglnx/libglnx.h"
+
+#include "xdg-app-builtins.h"
+#include "xdg-app-utils.h"
+#include "xdg-app-dbus.h"
+#include "xdg-app-run.h"
+
+
+static GOptionEntry options[] = {
+  { NULL }
+};
+
+static gboolean
+write_to_file (int fd, const char *content, ssize_t len)
+{
+  ssize_t res;
+
+  while (len > 0)
+    {
+      res = write (fd, content, len);
+      if (res < 0 && errno == EINTR)
+	continue;
+      if (res <= 0)
+	return FALSE;
+      len -= res;
+      content += res;
+    }
+
+  return TRUE;
+}
+
+static gboolean
+write_file (const char *path, const char *content)
+{
+  int fd;
+  gboolean res;
+  int errsv;
+
+  fd = open (path, O_RDWR | O_CLOEXEC, 0);
+  if (fd == -1)
+    return FALSE;
+
+  res = TRUE;
+  if (content)
+    res = write_to_file (fd, content, strlen (content));
+
+  errsv = errno;
+  close (fd);
+  errno = errsv;
+
+  return res;
+}
+
+static uid_t uid;
+static gid_t gid;
+
+static void
+child_setup (gpointer user_data)
+{
+#ifndef DISABLE_USERNS
+  g_autofree char *uid_map = NULL;
+  g_autofree char *gid_map = NULL;
+        
+  /* Work around user namespace devpts issue by creating a new
+     userspace and map our uid like the helper does */
+
+  if (unshare (CLONE_NEWUSER))
+    {
+      g_warning ("Can't unshare user namespace: %s", strerror (errno));
+      return;
+    }
+
+  uid_map = g_strdup_printf ("%d 0 1\n", uid);
+  if (!write_file ("/proc/self/uid_map", uid_map))
+    g_warning ("setting up uid map");
+
+  gid_map = g_strdup_printf ("%d 0 1\n", gid);
+  if (!write_file ("/proc/self/gid_map", gid_map))
+    g_warning ("setting up gid map");
+
+#endif
+}
+
+gboolean
+xdg_app_builtin_enter (int argc,
+                       char **argv,
+                       GCancellable *cancellable,
+                       GError **error)
+{
+  g_autoptr(GOptionContext) context = NULL;
+  int rest_argv_start, rest_argc;
+  g_autoptr(XdgAppContext) arg_context = NULL;
+  const char *ns_name[5] = { "user", "ipc", "net", "pid", "mnt" };
+  int ns_fd[G_N_ELEMENTS(ns_name)];
+  char pid_ns[256];
+  ssize_t pid_ns_len;
+  char self_ns[256];
+  ssize_t self_ns_len;
+  char *pid_s;
+  int pid, i;
+  g_autofree char *environment_path = NULL;
+  g_autoptr(GPtrArray) argv_array = NULL;
+  g_autoptr(GPtrArray) envp_array = NULL;
+  g_autofree char *environment = NULL;
+  gsize environment_len;
+  char *e;
+  g_autofree char *pulse_path = NULL;
+  g_autofree char *session_bus_path = NULL;
+  g_autofree char *xdg_runtime_dir = NULL;
+  int status;
+
+  uid = getuid ();
+  gid = getgid ();
+
+  context = g_option_context_new ("MONITORPID [COMMAND [args...]] - Run a command inside a running sandbox");
+
+  rest_argc = 0;
+  for (i = 1; i < argc; i++)
+    {
+      /* The non-option is the command, take it out of the arguments */
+      if (argv[i][0] != '-')
+        {
+          rest_argv_start = i;
+          rest_argc = argc - i;
+          argc = i;
+          break;
+        }
+    }
+
+  arg_context = xdg_app_context_new ();
+  g_option_context_add_group (context, xdg_app_context_get_options (arg_context));
+
+  if (!xdg_app_option_context_parse (context, options, &argc, &argv, XDG_APP_BUILTIN_FLAG_NO_DIR, NULL, cancellable, error))
+    return FALSE;
+
+  if (rest_argc < 2)
+    {
+      usage_error (context, "MONITORPID and COMMAND must be specified", error);
+      return FALSE;
+    }
+
+  pid_s = argv[rest_argv_start];
+
+  pid = atoi (pid_s);
+  if (pid <= 0)
+    {
+      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED, "Invalid pid %s\n", pid_s);
+      return FALSE;
+    }
+
+  environment_path = g_strdup_printf ("/proc/%d/environ", pid);
+  if (!g_file_get_contents (environment_path, &environment, &environment_len, error))
+    return FALSE;
+
+  for (i = 0; i < G_N_ELEMENTS(ns_name); i++)
+    {
+      g_autofree char *path = g_strdup_printf ("/proc/%d/ns/%s", pid, ns_name[i]);
+      g_autofree char *self_path = g_strdup_printf ("/proc/self/ns/%s", ns_name[i]);
+
+      pid_ns_len = readlink (path, pid_ns, sizeof (pid_ns) - 1);
+      if (pid_ns_len <= 0)
+        {
+          g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED, "Invalid %s namespace for pid %d\n", ns_name[i], pid);
+          return FALSE;
+        }
+      pid_ns[pid_ns_len] = 0;
+
+      self_ns_len = readlink (self_path, self_ns, sizeof (self_ns) - 1);
+      if (self_ns_len <= 0)
+      if (pid_ns_len <= 0)
+        {
+          g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED, "Invalid %s namespace for self\n", ns_name[i]);
+          return FALSE;
+        }
+      self_ns[self_ns_len] = 0;
+
+      if (strcmp (self_ns, pid_ns) == 0)
+        {
+          /* No need to setns to the same namespace, it will only fail */
+          ns_fd[i] = -1;
+        }
+      else
+        {
+          ns_fd[i] = open (path, O_RDONLY);
+          if (ns_fd[i] == -1)
+            {
+              g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED, "Can't open %s namespace: %s", ns_name[i], strerror (errno));
+              return FALSE;
+            }
+        }
+    }
+  
+  for (i = 0; i < G_N_ELEMENTS(ns_fd); i++)
+    {
+      if (ns_fd[i] != -1)
+        {
+          if (setns (ns_fd[i], 0) == -1)
+            {
+              g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED, "Can't enter %s namespace: %s", ns_name[i], strerror (errno));
+              return FALSE;
+            }
+          close (ns_fd[i]);
+        }
+    }
+
+  envp_array = g_ptr_array_new_with_free_func (g_free);
+  for (e = environment; e < environment + environment_len; e = e + strlen (e) + 1)
+    {
+      if (*e != 0 &&
+          !g_str_has_prefix (e, "DISPLAY=") &&
+          !g_str_has_prefix (e, "PULSE_SERVER=") &&
+          !g_str_has_prefix (e, "PULSE_CLIENTCONFIG=") &&
+          !g_str_has_prefix (e, "XDG_RUNTIME_DIR=") &&
+          !g_str_has_prefix (e, "DBUS_SYSTEM_BUS_ADDRESS=") &&
+          !g_str_has_prefix (e, "DBUS_SESSION_BUS_ADDRESS="))
+        {
+          if (g_str_has_prefix (e, "_LD_LIBRARY_PATH="))
+            e++;
+          g_ptr_array_add (envp_array, g_strdup (e));
+        }
+    }
+
+  xdg_runtime_dir = g_strdup_printf ("/run/user/%d", uid);
+  g_ptr_array_add (envp_array, g_strdup_printf ("XDG_RUNTIME_DIR=%s", xdg_runtime_dir));
+      
+  if (g_file_test ("/tmp/.X11-unix/X99", G_FILE_TEST_EXISTS))
+    g_ptr_array_add (envp_array, g_strdup ("DISPLAY=:99.0"));
+
+  pulse_path = g_strdup_printf ("/run/user/%d/pulse/native", uid);
+  if (g_file_test (pulse_path, G_FILE_TEST_EXISTS))
+    {
+      g_ptr_array_add (envp_array, g_strdup_printf ("PULSE_SERVER=unix:%s", pulse_path));
+      g_ptr_array_add (envp_array, g_strdup_printf ("PULSE_CLIENTCONFIG=/run/user/%d/pulse/config", uid));
+    }
+
+  session_bus_path = g_strdup_printf ("/run/user/%d/bus", uid);
+  if (g_file_test (session_bus_path, G_FILE_TEST_EXISTS))
+    g_ptr_array_add (envp_array, g_strdup_printf ("DBUS_SESSION_BUS_ADDRESS=unix:%s", session_bus_path));
+
+  if (g_file_test ("/run/dbus/system_bus_socket", G_FILE_TEST_EXISTS))
+    g_ptr_array_add (envp_array, g_strdup ("DBUS_SYSTEM_BUS_ADDRESS=unix:/run/dbus/system_bus_socket"));
+  
+  g_ptr_array_add (envp_array, NULL);
+  
+  argv_array = g_ptr_array_new_with_free_func (g_free);
+  for (i = 1; i < rest_argc; i++)
+    g_ptr_array_add (argv_array, g_strdup (argv[rest_argv_start + i]));
+  g_ptr_array_add (argv_array, NULL);
+
+  if (!g_spawn_sync (NULL, (char **)argv_array->pdata, (char **)envp_array->pdata,
+                     G_SPAWN_SEARCH_PATH_FROM_ENVP | G_SPAWN_CHILD_INHERITS_STDIN,
+                     child_setup, NULL,
+                     NULL, NULL,
+                     &status, error))
+    return FALSE;
+
+  exit (status);
+}

app/xdg-app-builtins.h

@@ -63,6 +63,7 @@ BUILTINPROTO(update_app);
 BUILTINPROTO(uninstall_app);
 BUILTINPROTO(list_apps);
 BUILTINPROTO(run);
+BUILTINPROTO(enter);
 BUILTINPROTO(build_init);
 BUILTINPROTO(build);
 BUILTINPROTO(build_finish);

app/xdg-app-main.c

@@ -56,6 +56,7 @@ static XdgAppCommand commands[] = {
   { "uninstall-app", xdg_app_builtin_uninstall_app },
   { "list-apps", xdg_app_builtin_list_apps },
   { "run", xdg_app_builtin_run },
+  { "enter", xdg_app_builtin_enter },
   { "override", xdg_app_builtin_override },
   { "export-file", xdg_app_builtin_export_file },
   { "build-init", xdg_app_builtin_build_init },

completion/xdg-app

@@ -23,7 +23,7 @@ _xdg-app() {
         local dir cmd sdk loc
 
         local -A VERBS=(
-                [ALL]='add-remote modify-remote delete-remote ls-remote list-remotes install-runtime update-runtime uninstall-runtime list-runtimes install-app update-app uninstall-app list-apps run override export-file build-init build build-finish build-export repo-update make-app-current'
+                [ALL]='add-remote modify-remote delete-remote ls-remote list-remotes install-runtime update-runtime uninstall-runtime list-runtimes install-app update-app uninstall-app list-apps run override enter export-file build-init build build-finish build-export repo-update make-app-current'
                 [MODE]='add-remote modify-remote delete-remote ls-remote list-remotes install-runtime update-runtime uninstall-runtime list-runtimes install-app update-app uninstall-app list-apps make-app-current'
                 [PERMS]='run override build build-finish'
                 [UNINSTALL]='uninstall-runtime uninstall-app'

doc/Makefile.am

@@ -30,6 +30,7 @@ man_MANS = \
 	xdg-app-list-apps.1	 	\
 	xdg-app-run.1		 	\
 	xdg-app-override.1		\
+	xdg-app-enter.1		 	\
 	xdg-app-export-file.1		\
 	xdg-app-build-init.1	 	\
 	xdg-app-build.1		 	\

doc/xdg-app-enter.xml

@@ -0,0 +1,110 @@
+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+    "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+
+<refentry id="xdg-app-enter">
+
+    <refentryinfo>
+        <title>xdg-app enter</title>
+        <productname>xdg-app</productname>
+
+        <authorgroup>
+            <author>
+                <contrib>Developer</contrib>
+                <firstname>Alexander</firstname>
+                <surname>Larsson</surname>
+                <email>alexl@redhat.com</email>
+            </author>
+        </authorgroup>
+    </refentryinfo>
+
+    <refmeta>
+        <refentrytitle>xdg-app enter</refentrytitle>
+        <manvolnum>1</manvolnum>
+    </refmeta>
+
+    <refnamediv>
+        <refname>xdg-app-enter</refname>
+        <refpurpose>Enter an application</refpurpose>
+    </refnamediv>
+
+    <refsynopsisdiv>
+            <cmdsynopsis>
+                <command>xdg-app enter</command>
+                <arg choice="opt" rep="repeat">OPTION</arg>
+                <arg choice="plain">MONITORPID</arg>
+                <arg choice="plain">COMMAND</arg>
+                <arg choice="opt" rep="repeat">ARG</arg>
+            </cmdsynopsis>
+    </refsynopsisdiv>
+
+    <refsect1>
+        <title>Description</title>
+
+        <para>
+            Enter a running sandbox.
+            <arg choice="plain">MONITORPID</arg> must be the pid of the monitor process for a running sandbox.
+            <arg choice="plain">COMMAND</arg> is the command to run in the sandbox.
+            Extra arguments are passed on to the command.
+        </para>
+        <para>
+            This creates a new process within the running sandbox, with the same environment. This is useful
+            when you want to debug a problem with a running application.
+        </para>
+
+    </refsect1>
+
+    <refsect1>
+        <title>Options</title>
+
+        <para>The following options are understood:</para>
+
+        <variablelist>
+            <varlistentry>
+                <term><option>-h</option></term>
+                <term><option>--help</option></term>
+
+                <listitem><para>
+                    Show help options and exit.
+                </para></listitem>
+            </varlistentry>
+
+            <varlistentry>
+                <term><option>-v</option></term>
+                <term><option>--verbose</option></term>
+
+                <listitem><para>
+                    Print debug information during command processing.
+                </para></listitem>
+            </varlistentry>
+
+            <varlistentry>
+                <term><option>--version</option></term>
+
+                <listitem><para>
+                    Print version information and exit.
+                </para></listitem>
+            </varlistentry>
+        </variablelist>
+    </refsect1>
+
+    <refsect1>
+        <title>Examples</title>
+
+        <para>
+            <command>$ xdg-app enter 15345 sh</command>
+        </para>
+
+    </refsect1>
+
+    <refsect1>
+        <title>See also</title>
+
+        <para>
+            <citerefentry><refentrytitle>xdg-app</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+            <citerefentry><refentrytitle>xdg-app-run</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+        </para>
+
+    </refsect1>
+
+</refentry>

doc/xdg-app-run.xml

@@ -274,6 +274,7 @@
         <para>
             <citerefentry><refentrytitle>xdg-app</refentrytitle><manvolnum>1</manvolnum></citerefentry>
             <citerefentry><refentrytitle>xdg-app-override</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+            <citerefentry><refentrytitle>xdg-app-enter</refentrytitle><manvolnum>1</manvolnum></citerefentry>
         </para>
 
     </refsect1>

lib/xdg-app-helper.c

@@ -2428,29 +2428,6 @@ main (int argc,
       free (tz_val);
     }
 
-#ifndef DISABLE_USERNS
-  {
-    char *uid_map, *gid_map;
-    /* Now that devpts is mounted we can create a new userspace and map
-       our uid 1:1 */
-    if (unshare (CLONE_NEWUSER))
-      die_with_error ("unshare user ns");
-
-    uid_map = strdup_printf ("%d 0 1\n", uid);
-    if (!write_file ("/proc/self/uid_map", uid_map))
-      die_with_error ("setting up uid map");
-    free (uid_map);
-
-    gid_map = strdup_printf ("%d 0 1\n", gid);
-    if (!write_file ("/proc/self/gid_map", gid_map))
-      die_with_error ("setting up gid map");
-    free (gid_map);
-  }
-#endif
-
-  __debug__(("setting up seccomp\n"));
-  setup_seccomp (devel);
-
   __debug__(("forking for child\n"));
 
   pid = fork ();
@@ -2461,6 +2438,30 @@ main (int argc,
     {
       __debug__(("launch executable %s\n", args[0]));
 
+#ifndef DISABLE_USERNS
+      {
+        char *uid_map, *gid_map;
+        /* Now that devpts is mounted we can create a new userspace and map
+           our uid 1:1 */
+
+        if (unshare (CLONE_NEWUSER))
+          die_with_error ("unshare user ns");
+
+        uid_map = strdup_printf ("%d 0 1\n", uid);
+        if (!write_file ("/proc/self/uid_map", uid_map))
+          die_with_error ("setting up uid map");
+        free (uid_map);
+
+        gid_map = strdup_printf ("%d 0 1\n", gid);
+        if (!write_file ("/proc/self/gid_map", gid_map))
+          die_with_error ("setting up gid map");
+        free (gid_map);
+      }
+#endif
+
+      __debug__(("setting up seccomp in child\n"));
+      setup_seccomp (devel);
+
       if (sync_fd != -1)
 	close (sync_fd);
 
@@ -2469,6 +2470,9 @@ main (int argc,
       return 0;
     }
 
+  __debug__(("setting up seccomp in monitor\n"));
+  setup_seccomp (devel);
+
   /* Close all extra fds in pid 1.
      Any passed in fds have been passed on to the child anyway. */
   {