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gspawn: Clarify that empty argv arrays are not allowed when spawning

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While `execve()` might allow (probably malicious) users to execute a
program with an empty `argv` array, gspawn does not. It’s not actually
possible, as the path to the binary to execute is not specified
separately from the argument array.

Explicitly document and encode that in preconditions.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
This commit is contained in:
Philip Withnall 2022-01-31 14:54:10 +00:00
parent 18fc711355
commit 44f4d55150
2 changed files with 28 additions and 11 deletions
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15
glib/gspawn-win32.c
View File

@ -236,7 +236,7 @@ g_spawn_async (const gchar *working_directory,
GPid *child_pid, GPid *child_pid,
GError **error) GError **error)
{ {
g_return_val_if_fail (argv != NULL, FALSE); g_return_val_if_fail (argv != NULL && argv[0] != NULL, FALSE);
return g_spawn_async_with_pipes (working_directory, return g_spawn_async_with_pipes (working_directory,
argv, envp, argv, envp,
@ -460,6 +460,8 @@ do_spawn_directly (gint *exit_status,
gint conv_error_index; gint conv_error_index;
wchar_t *wargv0, **wargv, **wenvp; wchar_t *wargv0, **wargv, **wenvp;
g_assert (argv != NULL && argv[0] != NULL);
new_argv = (flags & G_SPAWN_FILE_AND_ARGV_ZERO) ? protected_argv + 1 : protected_argv; new_argv = (flags & G_SPAWN_FILE_AND_ARGV_ZERO) ? protected_argv + 1 : protected_argv;
wargv0 = g_utf8_to_utf16 (argv[0], -1, NULL, NULL, &conv_error); wargv0 = g_utf8_to_utf16 (argv[0], -1, NULL, NULL, &conv_error);
@ -601,6 +603,7 @@ fork_exec (gint *exit_status,
int stdout_pipe[2] = { -1, -1 }; int stdout_pipe[2] = { -1, -1 };
int stderr_pipe[2] = { -1, -1 }; int stderr_pipe[2] = { -1, -1 };
g_assert (argv != NULL && argv[0] != NULL);
g_assert (stdin_pipe_out == NULL || stdin_fd < 0); g_assert (stdin_pipe_out == NULL || stdin_fd < 0);
g_assert (stdout_pipe_out == NULL || stdout_fd < 0); g_assert (stdout_pipe_out == NULL || stdout_fd < 0);
g_assert (stderr_pipe_out == NULL || stderr_fd < 0); g_assert (stderr_pipe_out == NULL || stderr_fd < 0);
@ -989,7 +992,7 @@ g_spawn_sync (const gchar *working_directory,
gboolean failed; gboolean failed;
gint status; gint status;
g_return_val_if_fail (argv != NULL, FALSE); g_return_val_if_fail (argv != NULL && argv[0] != NULL, FALSE);
g_return_val_if_fail (!(flags & G_SPAWN_DO_NOT_REAP_CHILD), FALSE); g_return_val_if_fail (!(flags & G_SPAWN_DO_NOT_REAP_CHILD), FALSE);
g_return_val_if_fail (standard_output == NULL || g_return_val_if_fail (standard_output == NULL ||
!(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE); !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
@ -1221,7 +1224,7 @@ g_spawn_async_with_pipes (const gchar *working_directory,
gint *standard_error, gint *standard_error,
GError **error) GError **error)
{ {
g_return_val_if_fail (argv != NULL, FALSE); g_return_val_if_fail (argv != NULL && argv[0] != NULL, FALSE);
g_return_val_if_fail (standard_output == NULL || g_return_val_if_fail (standard_output == NULL ||
!(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE); !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
g_return_val_if_fail (standard_error == NULL || g_return_val_if_fail (standard_error == NULL ||
@ -1263,7 +1266,7 @@ g_spawn_async_with_fds (const gchar *working_directory,
gint stderr_fd, gint stderr_fd,
GError **error) GError **error)
{ {
g_return_val_if_fail (argv != NULL, FALSE); g_return_val_if_fail (argv != NULL && argv[0] != NULL, FALSE);
g_return_val_if_fail (stdin_fd == -1 || g_return_val_if_fail (stdin_fd == -1 ||
!(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE); !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
g_return_val_if_fail (stderr_fd == -1 || g_return_val_if_fail (stderr_fd == -1 ||
@ -1312,7 +1315,7 @@ g_spawn_async_with_pipes_and_fds (const gchar *working_directory,
gint *stderr_pipe_out, gint *stderr_pipe_out,
GError **error) GError **error)
{ {
g_return_val_if_fail (argv != NULL, FALSE); g_return_val_if_fail (argv != NULL && argv[0] != NULL, FALSE);
g_return_val_if_fail (stdout_pipe_out == NULL || g_return_val_if_fail (stdout_pipe_out == NULL ||
!(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE); !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
g_return_val_if_fail (stderr_pipe_out == NULL || g_return_val_if_fail (stderr_pipe_out == NULL ||
@ -1359,6 +1362,7 @@ g_spawn_command_line_sync (const gchar *command_line,
g_return_val_if_fail (command_line != NULL, FALSE); g_return_val_if_fail (command_line != NULL, FALSE);
/* This will return a runtime error if @command_line is the empty string. */
if (!g_shell_parse_argv (command_line, if (!g_shell_parse_argv (command_line,
NULL, &argv, NULL, &argv,
error)) error))
@ -1388,6 +1392,7 @@ g_spawn_command_line_async (const gchar *command_line,
g_return_val_if_fail (command_line != NULL, FALSE); g_return_val_if_fail (command_line != NULL, FALSE);
/* This will return a runtime error if @command_line is the empty string. */
if (!g_shell_parse_argv (command_line, if (!g_shell_parse_argv (command_line,
NULL, &argv, NULL, &argv,
error)) error))

24
glib/gspawn.c
View File

@ -319,7 +319,7 @@ read_data (GString *str,
* @working_directory: (type filename) (nullable): child's current working * @working_directory: (type filename) (nullable): child's current working
* directory, or %NULL to inherit parent's * directory, or %NULL to inherit parent's
* @argv: (array zero-terminated=1) (element-type filename): * @argv: (array zero-terminated=1) (element-type filename):
* child's argument vector * child's argument vector, which must be non-empty and %NULL-terminated
* @envp: (array zero-terminated=1) (element-type filename) (nullable): * @envp: (array zero-terminated=1) (element-type filename) (nullable):
* child's environment, or %NULL to inherit parent's * child's environment, or %NULL to inherit parent's
* @flags: flags from #GSpawnFlags * @flags: flags from #GSpawnFlags
@ -378,6 +378,7 @@ g_spawn_sync (const gchar *working_directory,
gint status; gint status;
g_return_val_if_fail (argv != NULL, FALSE); g_return_val_if_fail (argv != NULL, FALSE);
g_return_val_if_fail (argv[0] != NULL, FALSE);
g_return_val_if_fail (!(flags & G_SPAWN_DO_NOT_REAP_CHILD), FALSE); g_return_val_if_fail (!(flags & G_SPAWN_DO_NOT_REAP_CHILD), FALSE);
g_return_val_if_fail (standard_output == NULL || g_return_val_if_fail (standard_output == NULL ||
!(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE); !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
@ -578,7 +579,7 @@ g_spawn_sync (const gchar *working_directory,
* @working_directory: (type filename) (nullable): child's current working * @working_directory: (type filename) (nullable): child's current working
* directory, or %NULL to inherit parent's, in the GLib file name encoding * directory, or %NULL to inherit parent's, in the GLib file name encoding
* @argv: (array zero-terminated=1) (element-type filename): child's argument * @argv: (array zero-terminated=1) (element-type filename): child's argument
* vector, in the GLib file name encoding * vector, in the GLib file name encoding; it must be non-empty and %NULL-terminated
* @envp: (array zero-terminated=1) (element-type filename) (nullable): * @envp: (array zero-terminated=1) (element-type filename) (nullable):
* child's environment, or %NULL to inherit parent's, in the GLib file * child's environment, or %NULL to inherit parent's, in the GLib file
* name encoding * name encoding
@ -610,6 +611,7 @@ g_spawn_async_with_pipes (const gchar *working_directory,
GError **error) GError **error)
{ {
g_return_val_if_fail (argv != NULL, FALSE); g_return_val_if_fail (argv != NULL, FALSE);
g_return_val_if_fail (argv[0] != NULL, FALSE);
g_return_val_if_fail (standard_output == NULL || g_return_val_if_fail (standard_output == NULL ||
!(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE); !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
g_return_val_if_fail (standard_error == NULL || g_return_val_if_fail (standard_error == NULL ||
@ -646,7 +648,7 @@ g_spawn_async_with_pipes (const gchar *working_directory,
* @working_directory: (type filename) (nullable): child's current working * @working_directory: (type filename) (nullable): child's current working
* directory, or %NULL to inherit parent's, in the GLib file name encoding * directory, or %NULL to inherit parent's, in the GLib file name encoding
* @argv: (array zero-terminated=1) (element-type filename): child's argument * @argv: (array zero-terminated=1) (element-type filename): child's argument
* vector, in the GLib file name encoding * vector, in the GLib file name encoding; it must be non-empty and %NULL-terminated
* @envp: (array zero-terminated=1) (element-type filename) (nullable): * @envp: (array zero-terminated=1) (element-type filename) (nullable):
* child's environment, or %NULL to inherit parent's, in the GLib file * child's environment, or %NULL to inherit parent's, in the GLib file
* name encoding * name encoding
@ -880,6 +882,7 @@ g_spawn_async_with_pipes_and_fds (const gchar *working_directory,
GError **error) GError **error)
{ {
g_return_val_if_fail (argv != NULL, FALSE); g_return_val_if_fail (argv != NULL, FALSE);
g_return_val_if_fail (argv[0] != NULL, FALSE);
g_return_val_if_fail (stdout_pipe_out == NULL || g_return_val_if_fail (stdout_pipe_out == NULL ||
!(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE); !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
g_return_val_if_fail (stderr_pipe_out == NULL || g_return_val_if_fail (stderr_pipe_out == NULL ||
@ -922,7 +925,8 @@ g_spawn_async_with_pipes_and_fds (const gchar *working_directory,
/** /**
* g_spawn_async_with_fds: * g_spawn_async_with_fds:
* @working_directory: (type filename) (nullable): child's current working directory, or %NULL to inherit parent's, in the GLib file name encoding * @working_directory: (type filename) (nullable): child's current working directory, or %NULL to inherit parent's, in the GLib file name encoding
* @argv: (array zero-terminated=1): child's argument vector, in the GLib file name encoding * @argv: (array zero-terminated=1): child's argument vector, in the GLib file name encoding;
* it must be non-empty and %NULL-terminated
* @envp: (array zero-terminated=1) (nullable): child's environment, or %NULL to inherit parent's, in the GLib file name encoding * @envp: (array zero-terminated=1) (nullable): child's environment, or %NULL to inherit parent's, in the GLib file name encoding
* @flags: flags from #GSpawnFlags * @flags: flags from #GSpawnFlags
* @child_setup: (scope async) (nullable): function to run in the child just before exec() * @child_setup: (scope async) (nullable): function to run in the child just before exec()
@ -956,6 +960,7 @@ g_spawn_async_with_fds (const gchar *working_directory,
GError **error) GError **error)
{ {
g_return_val_if_fail (argv != NULL, FALSE); g_return_val_if_fail (argv != NULL, FALSE);
g_return_val_if_fail (argv[0] != NULL, FALSE);
g_return_val_if_fail (stdout_fd < 0 || g_return_val_if_fail (stdout_fd < 0 ||
!(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE); !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
g_return_val_if_fail (stderr_fd < 0 || g_return_val_if_fail (stderr_fd < 0 ||
@ -1039,6 +1044,7 @@ g_spawn_command_line_sync (const gchar *command_line,
g_return_val_if_fail (command_line != NULL, FALSE); g_return_val_if_fail (command_line != NULL, FALSE);
/* This will return a runtime error if @command_line is the empty string. */
if (!g_shell_parse_argv (command_line, if (!g_shell_parse_argv (command_line,
NULL, &argv, NULL, &argv,
error)) error))
@ -1086,6 +1092,7 @@ g_spawn_command_line_async (const gchar *command_line,
g_return_val_if_fail (command_line != NULL, FALSE); g_return_val_if_fail (command_line != NULL, FALSE);
/* This will return a runtime error if @command_line is the empty string. */
if (!g_shell_parse_argv (command_line, if (!g_shell_parse_argv (command_line,
NULL, &argv, NULL, &argv,
error)) error))
@ -1636,7 +1643,9 @@ enum
}; };
/* This function is called between fork() and exec() and hence must be /* This function is called between fork() and exec() and hence must be
* async-signal-safe (see signal-safety(7)) until it calls exec(). */ * async-signal-safe (see signal-safety(7)) until it calls exec().
*
* All callers must guarantee that @argv and @argv[0] are non-NULL. */
static void static void
do_exec (gint child_err_report_fd, do_exec (gint child_err_report_fd,
gint stdin_fd, gint stdin_fd,
@ -1926,6 +1935,8 @@ do_posix_spawn (const gchar * const *argv,
gsize i; gsize i;
int r; int r;
g_assert (argv != NULL && argv[0] != NULL);
if (*argv[0] == '\0') if (*argv[0] == '\0')
{ {
/* We check the simple case first. */ /* We check the simple case first. */
@ -2176,6 +2187,7 @@ fork_exec (gboolean intermediate_child,
gint n_child_close_fds = 0; gint n_child_close_fds = 0;
gint *source_fds_copy = NULL; gint *source_fds_copy = NULL;
g_assert (argv != NULL && argv[0] != NULL);
g_assert (stdin_pipe_out == NULL || stdin_fd < 0); g_assert (stdin_pipe_out == NULL || stdin_fd < 0);
g_assert (stdout_pipe_out == NULL || stdout_fd < 0); g_assert (stdout_pipe_out == NULL || stdout_fd < 0);
g_assert (stderr_pipe_out == NULL || stderr_fd < 0); g_assert (stderr_pipe_out == NULL || stderr_fd < 0);
@ -2734,7 +2746,7 @@ g_execute (const gchar *file,
gchar *search_path_buffer, gchar *search_path_buffer,
gsize search_path_buffer_len) gsize search_path_buffer_len)
{ {
if (*file == '\0') if (file == NULL || *file == '\0')
{ {
/* We check the simple case first. */ /* We check the simple case first. */
errno = ENOENT; errno = ENOENT;