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flatpak/common/flatpak-run-dbus.c
Simon McVittie 7b1cd20696 Replace flatpak_close_fds_workaround() with g_fdwalk_set_cloexec() 
flatpak_close_fds_workaround() wasn't technically async-signal-safe,
because the requirement for sysconf() to be async-signal-safe was
removed in POSIX.1-2008.

It could also leave high fds open in some cases: in practice
sysconf(_SC_OPEN_MAX) returns the soft resource limit, but if our
resource limit has been reduced by an ancestor process, we could
conceivably still have fds open and inherited above that number.

We can fix this by using g_fdwalk_set_cloexec() with GLib >= 2.79.2,
or the backport in libglnx with older GLib. This uses close_range()
if possible, falling back to rummaging in /proc with async-signal-safe
syscalls.

Signed-off-by: Simon McVittie <smcv@collabora.com>
2024-02-15 16:06:41 +00:00

448 lines
16 KiB
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/* vi:set et sw=2 sts=2 cin cino=t0,f0,(0,{s,>2s,n-s,^-s,e-s:
* Copyright © 2014-2019 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 2.1 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 "flatpak-run-dbus-private.h"
#include <glib/gi18n-lib.h>
#include <sys/vfs.h>
#include "flatpak-utils-private.h"
/* This wraps the argv in a bwrap call, primary to allow the
command to be run with a proper /.flatpak-info with data
taken from app_info_path */
static gboolean
add_bwrap_wrapper (FlatpakBwrap *bwrap,
const char *app_info_path,
GError **error)
{
glnx_autofd int app_info_fd = -1;
g_auto(GLnxDirFdIterator) dir_iter = { 0 };
struct dirent *dent;
g_autofree char *user_runtime_dir = flatpak_get_real_xdg_runtime_dir ();
g_autofree char *proxy_socket_dir = g_build_filename (user_runtime_dir, ".dbus-proxy/", NULL);
app_info_fd = open (app_info_path, O_RDONLY | O_CLOEXEC);
if (app_info_fd == -1)
return glnx_throw_errno_prefix (error, _("Failed to open app info file"));
if (!glnx_dirfd_iterator_init_at (AT_FDCWD, "/", FALSE, &dir_iter, error))
return FALSE;
flatpak_bwrap_add_arg (bwrap, flatpak_get_bwrap ());
while (TRUE)
{
glnx_autofd int o_path_fd = -1;
struct statfs stfs;
if (!glnx_dirfd_iterator_next_dent_ensure_dtype (&dir_iter, &dent, NULL, error))
return FALSE;
if (dent == NULL)
break;
if (strcmp (dent->d_name, ".flatpak-info") == 0)
continue;
/* O_PATH + fstatfs is the magic that we need to statfs without automounting the target */
o_path_fd = openat (dir_iter.fd, dent->d_name, O_PATH | O_NOFOLLOW | O_CLOEXEC);
if (o_path_fd == -1 || fstatfs (o_path_fd, &stfs) != 0 || stfs.f_type == AUTOFS_SUPER_MAGIC)
continue; /* AUTOFS mounts are risky and can cause us to block (see issue #1633), so ignore it. Its unlikely the proxy needs such a directory. */
if (dent->d_type == DT_DIR)
{
if (strcmp (dent->d_name, "tmp") == 0 ||
strcmp (dent->d_name, "var") == 0 ||
strcmp (dent->d_name, "run") == 0)
flatpak_bwrap_add_arg (bwrap, "--bind");
else
flatpak_bwrap_add_arg (bwrap, "--ro-bind");
flatpak_bwrap_add_arg_printf (bwrap, "/%s", dent->d_name);
flatpak_bwrap_add_arg_printf (bwrap, "/%s", dent->d_name);
}
else if (dent->d_type == DT_LNK)
{
g_autofree gchar *target = NULL;
target = glnx_readlinkat_malloc (dir_iter.fd, dent->d_name,
NULL, error);
if (target == NULL)
return FALSE;
flatpak_bwrap_add_args (bwrap, "--symlink", target, NULL);
flatpak_bwrap_add_arg_printf (bwrap, "/%s", dent->d_name);
}
}
flatpak_bwrap_add_args (bwrap, "--bind", proxy_socket_dir, proxy_socket_dir, NULL);
/* This is a file rather than a bind mount, because it will then
not be unmounted from the namespace when the namespace dies. */
flatpak_bwrap_add_args (bwrap, "--perms", "0600", NULL);
flatpak_bwrap_add_args_data_fd (bwrap, "--file", g_steal_fd (&app_info_fd), "/.flatpak-info");
if (!flatpak_bwrap_bundle_args (bwrap, 1, -1, FALSE, error))
return FALSE;
return TRUE;
}
gboolean
flatpak_run_maybe_start_dbus_proxy (FlatpakBwrap *app_bwrap,
FlatpakBwrap *proxy_arg_bwrap,
const char *app_info_path,
GError **error)
{
char x = 'x';
const char *proxy;
g_autofree char *commandline = NULL;
g_autoptr(FlatpakBwrap) proxy_bwrap = NULL;
int proxy_start_index;
int sync_fd;
if (flatpak_bwrap_is_empty (proxy_arg_bwrap))
{
g_debug ("D-Bus proxy not needed");
return TRUE;
}
proxy_bwrap = flatpak_bwrap_new (NULL);
if (!add_bwrap_wrapper (proxy_bwrap, app_info_path, error))
return FALSE;
proxy = g_getenv ("FLATPAK_DBUSPROXY");
if (proxy == NULL)
proxy = DBUSPROXY;
flatpak_bwrap_add_arg (proxy_bwrap, proxy);
proxy_start_index = proxy_bwrap->argv->len;
sync_fd = flatpak_bwrap_add_sync_fd (app_bwrap);
if (sync_fd < 0)
{
g_set_error_literal (error, G_IO_ERROR, g_io_error_from_errno (errno),
_("Unable to create sync pipe"));
return FALSE;
}
flatpak_bwrap_add_fd (proxy_bwrap, sync_fd);
flatpak_bwrap_add_arg_printf (proxy_bwrap, "--fd=%d", sync_fd);
/* Note: This steals the fds from proxy_arg_bwrap */
flatpak_bwrap_append_bwrap (proxy_bwrap, proxy_arg_bwrap);
if (!flatpak_bwrap_bundle_args (proxy_bwrap, proxy_start_index, -1, TRUE, error))
return FALSE;
flatpak_bwrap_finish (proxy_bwrap);
commandline = flatpak_quote_argv ((const char **) proxy_bwrap->argv->pdata, -1);
g_info ("Running '%s'", commandline);
/* We use LEAVE_DESCRIPTORS_OPEN and close them in the child_setup
* to work around a deadlock in GLib < 2.60 */
if (!g_spawn_async (NULL,
(char **) proxy_bwrap->argv->pdata,
NULL,
G_SPAWN_SEARCH_PATH | G_SPAWN_LEAVE_DESCRIPTORS_OPEN,
flatpak_bwrap_child_setup_cb, proxy_bwrap->fds,
NULL, error))
return FALSE;
/* The write end can be closed now, otherwise the read below will hang of xdg-dbus-proxy
fails to start. */
g_clear_pointer (&proxy_bwrap, flatpak_bwrap_free);
/* Sync with proxy, i.e. wait until its listening on the sockets */
if (read (app_bwrap->sync_fds[0], &x, 1) != 1)
{
g_set_error_literal (error, G_IO_ERROR, g_io_error_from_errno (errno),
_("Failed to sync with dbus proxy"));
return FALSE;
}
return TRUE;
}
static char *
extract_unix_path_from_dbus_address (const char *address)
{
const char *path, *path_end;
if (address == NULL)
return NULL;
if (!g_str_has_prefix (address, "unix:"))
return NULL;
path = strstr (address, "path=");
if (path == NULL)
return NULL;
path += strlen ("path=");
path_end = path;
while (*path_end != 0 && *path_end != ',')
path_end++;
return g_strndup (path, path_end - path);
}
static char *
create_proxy_socket (char *template)
{
g_autofree char *user_runtime_dir = flatpak_get_real_xdg_runtime_dir ();
g_autofree char *proxy_socket_dir = g_build_filename (user_runtime_dir, ".dbus-proxy", NULL);
g_autofree char *proxy_socket = g_build_filename (proxy_socket_dir, template, NULL);
int fd;
if (!glnx_shutil_mkdir_p_at (AT_FDCWD, proxy_socket_dir, 0755, NULL, NULL))
return NULL;
fd = g_mkstemp (proxy_socket);
if (fd == -1)
return NULL;
close (fd);
return g_steal_pointer (&proxy_socket);
}
gboolean
flatpak_run_add_session_dbus_args (FlatpakBwrap *app_bwrap,
FlatpakBwrap *proxy_arg_bwrap,
FlatpakContext *context,
FlatpakRunFlags flags,
const char *app_id)
{
static const char sandbox_socket_path[] = "/run/flatpak/bus";
static const char sandbox_dbus_address[] = "unix:path=/run/flatpak/bus";
gboolean unrestricted, no_proxy;
const char *dbus_address = g_getenv ("DBUS_SESSION_BUS_ADDRESS");
g_autofree char *dbus_session_socket = NULL;
unrestricted = (context->sockets & FLATPAK_CONTEXT_SOCKET_SESSION_BUS) != 0;
if (dbus_address != NULL)
{
dbus_session_socket = extract_unix_path_from_dbus_address (dbus_address);
}
else
{
g_autofree char *user_runtime_dir = flatpak_get_real_xdg_runtime_dir ();
struct stat statbuf;
dbus_session_socket = g_build_filename (user_runtime_dir, "bus", NULL);
if (stat (dbus_session_socket, &statbuf) < 0
|| (statbuf.st_mode & S_IFMT) != S_IFSOCK
|| statbuf.st_uid != getuid ())
return FALSE;
}
if (unrestricted)
g_info ("Allowing session-dbus access");
no_proxy = (flags & FLATPAK_RUN_FLAG_NO_SESSION_BUS_PROXY) != 0;
if (dbus_session_socket != NULL && unrestricted)
{
flatpak_bwrap_add_args (app_bwrap,
"--ro-bind", dbus_session_socket, sandbox_socket_path,
NULL);
flatpak_bwrap_set_env (app_bwrap, "DBUS_SESSION_BUS_ADDRESS", sandbox_dbus_address, TRUE);
flatpak_bwrap_add_runtime_dir_member (app_bwrap, "bus");
return TRUE;
}
else if (!no_proxy && dbus_address != NULL)
{
g_autofree char *proxy_socket = create_proxy_socket ("session-bus-proxy-XXXXXX");
if (proxy_socket == NULL)
return FALSE;
flatpak_bwrap_add_args (proxy_arg_bwrap, dbus_address, proxy_socket, NULL);
if (!unrestricted)
{
flatpak_context_add_bus_filters (context, app_id, TRUE, flags & FLATPAK_RUN_FLAG_SANDBOX, proxy_arg_bwrap);
/* Allow calling any interface+method on all portals, but only receive broadcasts under /org/desktop/portal */
flatpak_bwrap_add_arg (proxy_arg_bwrap,
"--call=org.freedesktop.portal.*=*");
flatpak_bwrap_add_arg (proxy_arg_bwrap,
"--broadcast=org.freedesktop.portal.*=@/org/freedesktop/portal/*");
}
if ((flags & FLATPAK_RUN_FLAG_LOG_SESSION_BUS) != 0)
flatpak_bwrap_add_args (proxy_arg_bwrap, "--log", NULL);
flatpak_bwrap_add_args (app_bwrap,
"--ro-bind", proxy_socket, sandbox_socket_path,
NULL);
flatpak_bwrap_set_env (app_bwrap, "DBUS_SESSION_BUS_ADDRESS", sandbox_dbus_address, TRUE);
flatpak_bwrap_add_runtime_dir_member (app_bwrap, "bus");
return TRUE;
}
return FALSE;
}
gboolean
flatpak_run_add_system_dbus_args (FlatpakBwrap *app_bwrap,
FlatpakBwrap *proxy_arg_bwrap,
FlatpakContext *context,
FlatpakRunFlags flags)
{
gboolean unrestricted, no_proxy;
const char *dbus_address = g_getenv ("DBUS_SYSTEM_BUS_ADDRESS");
g_autofree char *real_dbus_address = NULL;
g_autofree char *dbus_system_socket = NULL;
unrestricted = (context->sockets & FLATPAK_CONTEXT_SOCKET_SYSTEM_BUS) != 0;
if (unrestricted)
g_info ("Allowing system-dbus access");
no_proxy = (flags & FLATPAK_RUN_FLAG_NO_SYSTEM_BUS_PROXY) != 0;
if (dbus_address != NULL)
dbus_system_socket = extract_unix_path_from_dbus_address (dbus_address);
else if (g_file_test ("/var/run/dbus/system_bus_socket", G_FILE_TEST_EXISTS))
dbus_system_socket = g_strdup ("/var/run/dbus/system_bus_socket");
if (dbus_system_socket != NULL && unrestricted)
{
flatpak_bwrap_add_args (app_bwrap,
"--ro-bind", dbus_system_socket, "/run/dbus/system_bus_socket",
NULL);
flatpak_bwrap_set_env (app_bwrap, "DBUS_SYSTEM_BUS_ADDRESS", "unix:path=/run/dbus/system_bus_socket", TRUE);
return TRUE;
}
else if (!no_proxy && flatpak_context_get_needs_system_bus_proxy (context))
{
g_autofree char *proxy_socket = create_proxy_socket ("system-bus-proxy-XXXXXX");
if (proxy_socket == NULL)
return FALSE;
if (dbus_address)
real_dbus_address = g_strdup (dbus_address);
else
real_dbus_address = g_strdup_printf ("unix:path=%s", dbus_system_socket);
flatpak_bwrap_add_args (proxy_arg_bwrap, real_dbus_address, proxy_socket, NULL);
if (!unrestricted)
flatpak_context_add_bus_filters (context, NULL, FALSE, flags & FLATPAK_RUN_FLAG_SANDBOX, proxy_arg_bwrap);
if ((flags & FLATPAK_RUN_FLAG_LOG_SYSTEM_BUS) != 0)
flatpak_bwrap_add_args (proxy_arg_bwrap, "--log", NULL);
flatpak_bwrap_add_args (app_bwrap,
"--ro-bind", proxy_socket, "/run/dbus/system_bus_socket",
NULL);
flatpak_bwrap_set_env (app_bwrap, "DBUS_SYSTEM_BUS_ADDRESS", "unix:path=/run/dbus/system_bus_socket", TRUE);
return TRUE;
}
return FALSE;
}
gboolean
flatpak_run_add_a11y_dbus_args (FlatpakBwrap *app_bwrap,
FlatpakBwrap *proxy_arg_bwrap,
FlatpakContext *context,
FlatpakRunFlags flags)
{
static const char sandbox_socket_path[] = "/run/flatpak/at-spi-bus";
static const char sandbox_dbus_address[] = "unix:path=/run/flatpak/at-spi-bus";
g_autoptr(GDBusConnection) session_bus = NULL;
g_autofree char *a11y_address = NULL;
g_autoptr(GError) local_error = NULL;
g_autoptr(GDBusMessage) reply = NULL;
g_autoptr(GDBusMessage) msg = NULL;
g_autofree char *proxy_socket = NULL;
if ((flags & FLATPAK_RUN_FLAG_NO_A11Y_BUS_PROXY) != 0)
return FALSE;
session_bus = g_bus_get_sync (G_BUS_TYPE_SESSION, NULL, NULL);
if (session_bus == NULL)
return FALSE;
msg = g_dbus_message_new_method_call ("org.a11y.Bus", "/org/a11y/bus", "org.a11y.Bus", "GetAddress");
g_dbus_message_set_body (msg, g_variant_new ("()"));
reply =
g_dbus_connection_send_message_with_reply_sync (session_bus, msg,
G_DBUS_SEND_MESSAGE_FLAGS_NONE,
30000,
NULL,
NULL,
NULL);
if (reply)
{
if (g_dbus_message_to_gerror (reply, &local_error))
{
if (!g_error_matches (local_error, G_DBUS_ERROR, G_DBUS_ERROR_SERVICE_UNKNOWN))
g_message ("Can't find a11y bus: %s", local_error->message);
}
else
{
g_variant_get (g_dbus_message_get_body (reply),
"(s)", &a11y_address);
}
}
if (!a11y_address)
return FALSE;
proxy_socket = create_proxy_socket ("a11y-bus-proxy-XXXXXX");
if (proxy_socket == NULL)
return FALSE;
flatpak_bwrap_add_args (proxy_arg_bwrap,
a11y_address,
proxy_socket, "--filter", "--sloppy-names",
"--call=org.a11y.atspi.Registry=org.a11y.atspi.Socket.Embed@/org/a11y/atspi/accessible/root",
"--call=org.a11y.atspi.Registry=org.a11y.atspi.Socket.Unembed@/org/a11y/atspi/accessible/root",
"--call=org.a11y.atspi.Registry=org.a11y.atspi.Registry.GetRegisteredEvents@/org/a11y/atspi/registry",
"--call=org.a11y.atspi.Registry=org.a11y.atspi.DeviceEventController.GetKeystrokeListeners@/org/a11y/atspi/registry/deviceeventcontroller",
"--call=org.a11y.atspi.Registry=org.a11y.atspi.DeviceEventController.GetDeviceEventListeners@/org/a11y/atspi/registry/deviceeventcontroller",
"--call=org.a11y.atspi.Registry=org.a11y.atspi.DeviceEventController.NotifyListenersSync@/org/a11y/atspi/registry/deviceeventcontroller",
"--call=org.a11y.atspi.Registry=org.a11y.atspi.DeviceEventController.NotifyListenersAsync@/org/a11y/atspi/registry/deviceeventcontroller",
NULL);
if ((flags & FLATPAK_RUN_FLAG_LOG_A11Y_BUS) != 0)
flatpak_bwrap_add_args (proxy_arg_bwrap, "--log", NULL);
flatpak_bwrap_add_args (app_bwrap,
"--ro-bind", proxy_socket, sandbox_socket_path,
NULL);
flatpak_bwrap_set_env (app_bwrap, "AT_SPI_BUS_ADDRESS", sandbox_dbus_address, TRUE);
return TRUE;
}
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