From 0a4c2503e0a6b1bdb34f3fa8f6644250eccbc445 Mon Sep 17 00:00:00 2001

From: Matthias Clasen <mclasen@redhat.com>

Date: Fri, 19 Mar 2010 19:28:56 -0400

Subject: [PATCH] Avoid extraneous commandline parsing

Switch to using g_spawn_sync instead of g_spawn_command_line_sync

to avoid the pointless roundtrip through a commandline parser, avoiding

some security pitfalls.

---

 src/daemon.c |   46 ++++++++++++++++--------

 src/user.c   |  115 ++++++++++++++++++++++++++++++++++------------------------

 2 files changed, 98 insertions(+), 63 deletions(-)

diff --git a/src/daemon.c b/src/daemon.c

index a962dc3..18a23fe 100644

--- a/src/daemon.c

+++ b/src/daemon.c

@@ -922,7 +922,7 @@ typedef struct {

         DBusGMethodInvocation *context;

 } ListUserData;

-ListUserData *

+static ListUserData *

 list_user_data_new (Daemon                *daemon,

                     DBusGMethodInvocation *context)

 {

@@ -1006,11 +1006,10 @@ daemon_create_user_authorized_cb (Daemon                *daemon,

 {

         CreateUserData *cd = data;

         User *user;

-        gchar *cmdline;

         GError *error;

         gchar *std_err, *std_out;

         gint status;

-        const gchar *grouparg;

+        gchar *argv[8];

         if (getpwnam (cd->user_name) != NULL) {

                 throw_error (context, ERROR_USER_EXISTS, "A user with name '%s' already exists", cd->user_name);

@@ -1022,22 +1021,32 @@ daemon_create_user_authorized_cb (Daemon                *daemon,

                           "create user '%s'",

                           cd->user_name);

+        argv[0] = "/usr/sbin/useradd";

+        argv[1] = "-m";

+        argv[2] = "-c";

+        argv[3] = cd->real_name;

         if (cd->account_type == ACCOUNT_TYPE_ADMINISTRATOR) {

-                grouparg = "-G desktop_admin_r";

+                argv[4] = "-G";

+                argv[5] = "desktop_admin_r";

+                argv[6] = cd->user_name;

+                argv[7] = NULL;

         }

         else if (cd->account_type == ACCOUNT_TYPE_STANDARD) {

-                grouparg = "-G desktop_user_r";

+                argv[4] = "-G";

+                argv[5] = "desktop_user_r";

+                argv[6] = cd->user_name;

+                argv[7] = NULL;

         }

         else {

-                grouparg = "";

+                argv[4] = cd->user_name;

+                argv[5] = NULL;

         }

-        cmdline = g_strdup_printf ("/usr/sbin/useradd -m -c '%s' %s %s", cd->real_name, grouparg, cd->user_name);

         std_out = NULL;

         std_err = NULL;

         error = NULL;

-        if (!g_spawn_command_line_sync (cmdline, &std_out, &std_err, &status, &error)) {

-                throw_error (context, ERROR_FAILED, "running '%s' failed: %s", cmdline, error->message);

+        if (!g_spawn_sync (NULL, argv, NULL, 0, NULL, NULL, &std_out, &std_err, &status, &error)) {

+                throw_error (context, ERROR_FAILED, "running '%s' failed: %s", argv[0], error->message);

                 g_error_free (error);

                 g_free (std_out);

                 g_free (std_err);

@@ -1051,7 +1060,6 @@ daemon_create_user_authorized_cb (Daemon                *daemon,

                 return;

         }

-        g_free (cmdline);

         g_free (std_out);

         g_free (std_err);

@@ -1099,12 +1107,12 @@ daemon_delete_user_authorized_cb (Daemon                *daemon,

 {

         DeleteUserData *ud = data;

-        gchar *cmdline;

         GError *error;

         gchar *std_err, *std_out;

         gint status;

         gchar *filename;

         struct passwd *pwent;

+        gchar *argv[4];

         pwent = getpwuid (ud->uid);

@@ -1118,13 +1126,22 @@ daemon_delete_user_authorized_cb (Daemon                *daemon,

                           "delete user '%s' (%d)",

                           pwent->pw_name, ud->uid);

-        cmdline = g_strdup_printf ("/usr/sbin/userdel %s%s", ud->remove_files ? "-r " : "", pwent->pw_name);

+        argv[0] = "/usr/sbin/userdel";

+        if (ud->remove_files) {

+                argv[1] = "-r";

+                argv[2] = pwent->pw_name;

+                argv[3] = NULL;

+        }

+        else {

+                argv[1] = pwent->pw_name;

+                argv[2] = NULL;

+        }

         std_out = NULL;

         std_err = NULL;

         error = NULL;

-        if (!g_spawn_command_line_sync (cmdline, &std_out, &std_err, &status, &error)) {

-                throw_error (context, ERROR_FAILED, "running '%s' failed: %s", cmdline, error->message);

+        if (!g_spawn_sync (NULL, argv, NULL, 0, NULL, NULL, &std_out, &std_err, &status, &error)) {

+                throw_error (context, ERROR_FAILED, "running '%s' failed: %s", argv[0], error->message);

                 g_error_free (error);

                 g_free (std_out);

                 g_free (std_err);

@@ -1142,7 +1159,6 @@ daemon_delete_user_authorized_cb (Daemon                *daemon,

         g_remove (filename);

         g_free (filename);

-        g_free (cmdline);

         dbus_g_method_return (context);

 }

diff --git a/src/user.c b/src/user.c

index a235411..cfdd16c 100644

--- a/src/user.c

+++ b/src/user.c

@@ -737,20 +737,24 @@ user_change_real_name_authorized_cb (Daemon                *daemon,

         GError *error;

         gint status;

         gchar *std_out, *std_err;

-        gchar *cmdline;

+        gchar *argv[5];

         if (g_strcmp0 (user->real_name, name) != 0) {

                 daemon_local_log (daemon, context,

                                   "change real name of user '%s' (%d) to '%s'",

                                   user->user_name, user->uid, name);

-                cmdline = g_strdup_printf ("/usr/sbin/usermod -c '%s' %s", name, user->user_name);

+                argv[0] = "/usr/sbin/usermod";

+                argv[1] = "-c";

+                argv[2] = name;

+                argv[3] = user->user_name;

+                argv[4] = NULL;

                 std_out = NULL;

                 std_err = NULL;

                 error = NULL;

-                if (!g_spawn_command_line_sync (cmdline, &std_out, &std_err, &status, &error)) {

-                        throw_error (context, ERROR_FAILED, "running '%s' failed: %s", cmdline, error->message);

+                if (!g_spawn_sync (NULL, argv, NULL, 0, NULL, NULL, &std_out, &std_err, &status, &error)) {

+                        throw_error (context, ERROR_FAILED, "running '%s' failed: %s", argv[0], error->message);

                         g_error_free (error);

                         g_free (std_out);

                         g_free (std_err);

@@ -761,13 +765,11 @@ user_change_real_name_authorized_cb (Daemon                *daemon,

                         throw_error (context, ERROR_FAILED, "usermod returned an error: %s", std_err);

                         g_free (std_out);

                         g_free (std_err);

-                        g_free (cmdline);

                         return;

                 }

                 g_free (std_out);

                 g_free (std_err);

-                g_free (cmdline);

                 g_free (user->real_name);

                 user->real_name = g_strdup (name);

@@ -831,7 +833,7 @@ user_change_user_name_authorized_cb (Daemon                *daemon,

         GError *error;

         gint status;

         gchar *std_out, *std_err;

-        gchar *cmdline;

+        gchar *argv[5];

         if (g_strcmp0 (user->user_name, name) != 0) {

                 old_name = g_strdup (user->user_name);

@@ -839,13 +841,17 @@ user_change_user_name_authorized_cb (Daemon                *daemon,

                                   "change name of user '%s' (%d) to '%s'",

                                   old_name, user->uid, name);

-                cmdline = g_strdup_printf ("/usr/sbin/usermod -l %s %s", name, user->user_name);

+                argv[0] = "/usr/sbin/usermod";

+                argv[1] = "-l";

+                argv[2] = name;

+                argv[3] = user->user_name;

+                argv[4] = NULL;

                 std_out = NULL;

                 std_err = NULL;

                 error = NULL;

-                if (!g_spawn_command_line_sync (cmdline, &std_out, &std_err, &status, &error)) {

-                        throw_error (context, ERROR_FAILED, "running '%s' failed: %s", cmdline, error->message);

+                if (!g_spawn_sync (NULL, argv, NULL, 0, NULL, NULL, &std_out, &std_err, &status, &error)) {

+                        throw_error (context, ERROR_FAILED, "running '%s' failed: %s", argv[0], error->message);

                         g_error_free (error);

                         g_free (std_out);

                         g_free (std_err);

@@ -856,13 +862,11 @@ user_change_user_name_authorized_cb (Daemon                *daemon,

                         throw_error (context, ERROR_FAILED, "usermod returned an error: %s", std_err);

                         g_free (std_out);

                         g_free (std_err);

-                        g_free (cmdline);

                         return;

                 }

                 g_free (std_out);

                 g_free (std_err);

-                g_free (cmdline);

                 g_free (user->user_name);

                 user->user_name = g_strdup (name);

@@ -1118,19 +1122,25 @@ user_change_home_dir_authorized_cb (Daemon                *daemon,

         GError *error;

         gint status;

         gchar *std_out, *std_err;

-        gchar *cmdline;

+        gchar *argv[6];

         if (g_strcmp0 (user->home_dir, home_dir) != 0) {

                 daemon_local_log (daemon, context,

                                   "change home directory of user '%s' (%d) to '%s'",

                                   user->user_name, user->uid, home_dir);

-                cmdline = g_strdup_printf ("/usr/sbin/usermod -m -d '%s' %s", home_dir, user->user_name);

+

+                argv[0] = "/usr/sbin/usermod";

+                argv[1] = "-m";

+                argv[2] = "-d";

+                argv[3] = home_dir;

+                argv[4] = user->user_name;

+                argv[5] = NULL;

                 std_out = NULL;

                 std_err = NULL;

                 error = NULL;

-                if (!g_spawn_command_line_sync (cmdline, &std_out, &std_err, &status, &error)) {

-                        throw_error (context, ERROR_FAILED, "running '%s' failed: %s", cmdline, error->message);

+                if (!g_spawn_sync (NULL, argv, NULL, 0, NULL, NULL, &std_out, &std_err, &status, &error)) {

+                        throw_error (context, ERROR_FAILED, "running '%s' failed: %s", argv[0], error->message);

                         g_error_free (error);

                         g_free (std_out);

                         g_free (std_err);

@@ -1141,13 +1151,11 @@ user_change_home_dir_authorized_cb (Daemon                *daemon,

                         throw_error (context, ERROR_FAILED, "usermod returned an error: %s", std_err);

                         g_free (std_out);

                         g_free (std_err);

-                        g_free (cmdline);

                         return;

                 }

                 g_free (std_out);

                 g_free (std_err);

-                g_free (cmdline);

                 g_free (user->home_dir);

                 user->home_dir = g_strdup (home_dir);

@@ -1159,6 +1167,7 @@ user_change_home_dir_authorized_cb (Daemon                *daemon,

         dbus_g_method_return (context);

 }

+

 gboolean

 user_set_home_directory (User                  *user,

                          const gchar           *home_dir,

@@ -1206,20 +1215,24 @@ user_change_shell_authorized_cb (Daemon                *daemon,

         GError *error;

         gint status;

         gchar *std_out, *std_err;

-        gchar *cmdline;

+        gchar *argv[5];

         if (g_strcmp0 (user->shell, shell) != 0) {

                 daemon_local_log (daemon, context,

                                   "change shell of user '%s' (%d) to '%s'",

                                   user->user_name, user->uid, shell);

-                cmdline = g_strdup_printf ("/usr/sbin/usermod -s '%s' %s", shell, user->user_name);

+                argv[0] = "/usr/sbin/usermod";

+                argv[1] = "-s";

+                argv[2] = shell;

+                argv[3] = user->user_name;

+                argv[4] = NULL;

                 std_out = NULL;

                 std_err = NULL;

                 error = NULL;

-                if (!g_spawn_command_line_sync (cmdline, &std_out, &std_err, &status, &error)) {

-                        throw_error (context, ERROR_FAILED, "running '%s' failed: %s", cmdline, error->message);

+                if (!g_spawn_sync (NULL, argv, NULL, 0, NULL, NULL, &std_out, &std_err, &status, &error)) {

+                        throw_error (context, ERROR_FAILED, "running '%s' failed: %s", argv[0], error->message);

                         g_error_free (error);

                         g_free (std_out);

                         g_free (std_err);

@@ -1230,13 +1243,11 @@ user_change_shell_authorized_cb (Daemon                *daemon,

                         throw_error (context, ERROR_FAILED, "usermod returned an error: %s", std_err);

                         g_free (std_out);

                         g_free (std_err);

-                        g_free (cmdline);

                         return;

                 }

                 g_free (std_out);

                 g_free (std_err);

-                g_free (cmdline);

                 g_free (user->shell);

                 user->shell = g_strdup (shell);

@@ -1475,19 +1486,22 @@ user_change_locked_authorized_cb (Daemon                *daemon,

         GError *error;

         gint status;

         gchar *std_out, *std_err;

-        gchar *cmdline;

+        gchar *argv[4];

         if (user->locked != locked) {

                 daemon_local_log (daemon, context,

                                   "%s account of user '%s' (%d)",

                                   locked ? "locking" : "unlocking", user->user_name, user->uid);

-                cmdline = g_strdup_printf ("/usr/sbin/usermod -%c %s", locked ? 'L' : 'U',  user->user_name);

+                argv[0] = "/usr/sbin/usermod";

+                argv[1] = locked ? "-L" : "-U";

+                argv[2] = user->user_name;

+                argv[3] = NULL;

                 std_out = NULL;

                 std_err = NULL;

                 error = NULL;

-                if (!g_spawn_command_line_sync (cmdline, &std_out, &std_err, &status, &error)) {

-                        throw_error (context, ERROR_FAILED, "running '%s' failed: %s", cmdline, error->message);

+                if (!g_spawn_sync (NULL, argv, NULL, 0, NULL, NULL, &std_out, &std_err, &status, &error)) {

+                        throw_error (context, ERROR_FAILED, "running '%s' failed: %s", argv[0], error->message);

                         g_error_free (error);

                         g_free (std_out);

                         g_free (std_err);

@@ -1498,13 +1512,11 @@ user_change_locked_authorized_cb (Daemon                *daemon,

                         throw_error (context, ERROR_FAILED, "usermod returned an error: %s", std_err);

                         g_free (std_out);

                         g_free (std_err);

-                        g_free (cmdline);

                         return;

                 }

                 g_free (std_out);

                 g_free (std_err);

-                g_free (cmdline);

                 user->locked = locked;

@@ -1544,7 +1556,6 @@ user_change_account_type_authorized_cb (Daemon                *daemon,

         GError *error;

         gint status;

         gchar *std_out, *std_err;

-        gchar *cmdline;

         gid_t groups[20];

         gint n_groups;

         GString *str;

@@ -1552,6 +1563,7 @@ user_change_account_type_authorized_cb (Daemon                *daemon,

         gid_t desktop_admin_r;

         struct group *grp;

         gint i;

+        gchar *argv[5];

         if (user->account_type != account_type) {

                 daemon_local_log (daemon, context,

@@ -1596,13 +1608,19 @@ user_change_account_type_authorized_cb (Daemon                *daemon,

                         g_string_truncate (str, str->len - 1);

                 }

-                cmdline = g_strdup_printf ("/usr/sbin/usermod -G %s %s", str->str, user->user_name);

+                argv[0] = "/usr/sbin/usermod";

+                argv[1] = "-G";

+                argv[2] = str->str;

+                argv[3] = user->user_name;

+                argv[4] = NULL;

+

+                g_string_free (str, FALSE);

                 std_out = NULL;

                 std_err = NULL;

                 error = NULL;

-                if (!g_spawn_command_line_sync (cmdline, &std_out, &std_err, &status, &error)) {

-                        throw_error (context, ERROR_FAILED, "running '%s' failed: %s", cmdline, error->message);

+                if (!g_spawn_sync (NULL, argv, NULL, 0, NULL, NULL, &std_out, &std_err, &status, &error)) {

+                        throw_error (context, ERROR_FAILED, "running '%s' failed: %s", argv[0], error->message);

                         g_error_free (error);

                         g_free (std_out);

                         g_free (std_err);

@@ -1613,13 +1631,11 @@ user_change_account_type_authorized_cb (Daemon                *daemon,

                         throw_error (context, ERROR_FAILED, "usermod returned an error: %s", std_err);

                         g_free (std_out);

                         g_free (std_err);

-                        g_free (cmdline);

                         return;

                 }

                 g_free (std_out);

                 g_free (std_err);

-                g_free (cmdline);

                 user->account_type = account_type;

@@ -1664,7 +1680,7 @@ user_change_password_mode_authorized_cb (Daemon                *daemon,

         GError *error;

         gint status;

         gchar *std_out, *std_err;

-        gchar *cmdline;

+        gchar *argv[4];

         if (user->password_mode != mode) {

                 daemon_local_log (daemon, context,

@@ -1674,13 +1690,16 @@ user_change_password_mode_authorized_cb (Daemon                *daemon,

                 if (mode == PASSWORD_MODE_SET_AT_LOGIN ||

                     mode == PASSWORD_MODE_NONE) {

-                        cmdline = g_strdup_printf ("/usr/bin/passwd -d %s", user->user_name);

+                        argv[0] = "/usr/bin/passwd";

+                        argv[1] = "-d";

+                        argv[2] = user->user_name;

+                        argv[3] = NULL;

                         std_out = NULL;

                         std_err = NULL;

                         error = NULL;

-                        if (!g_spawn_command_line_sync (cmdline, &std_out, &std_err, &status, &error)) {

-                                throw_error (context, ERROR_FAILED, "running '%s' failed: %s", cmdline, error->message);

+                        if (!g_spawn_sync (NULL, argv, NULL, 0, NULL, NULL, &std_out, &std_err, &status, &error)) {

+                                throw_error (context, ERROR_FAILED, "running '%s' failed: %s", argv[0], error->message);

                                 g_error_free (error);

                                 g_free (std_out);

                                 g_free (std_err);

@@ -1691,13 +1710,11 @@ user_change_password_mode_authorized_cb (Daemon                *daemon,

                                 throw_error (context, ERROR_FAILED, "usermod returned an error: %s", std_err);

                                 g_free (std_out);

                                 g_free (std_err);

-                                g_free (cmdline);

                                 return;

                         }

                         g_free (std_out);

                         g_free (std_err);

-                        g_free (cmdline);

                         g_free (user->password_hint);

                         user->password_hint = NULL;

@@ -1774,19 +1791,23 @@ user_change_password_authorized_cb (Daemon                *daemon,

         GError *error;

         gint status;

         gchar *std_out, *std_err;

-        gchar *cmdline;

+        gchar *argv[5];

         daemon_local_log (daemon, context,

                           "set password and hint of user '%s' (%d)",

                           user->user_name, user->uid);

-        cmdline = g_strdup_printf ("/usr/sbin/usermod -p '%s' %s", strings[0], user->user_name);

+        argv[0] = "/usr/sbin/usermod";

+        argv[1] = "-p";

+        argv[2] = strings[0];

+        argv[3] = user->user_name;

+        argv[4] = NULL;

         std_out = NULL;

         std_err = NULL;

         error = NULL;

-        if (!g_spawn_command_line_sync (cmdline, &std_out, &std_err, &status, &error)) {

-                throw_error (context, ERROR_FAILED, "running '%s' failed: %s", cmdline, error->message);

+        if (!g_spawn_sync (NULL, argv, NULL, 0, NULL, NULL, &std_out, &std_err, &status, &error)) {

+                throw_error (context, ERROR_FAILED, "running '%s' failed: %s", argv[0], error->message);

                 g_error_free (error);

                 g_free (std_out);

                 g_free (std_err);

@@ -1797,13 +1818,11 @@ user_change_password_authorized_cb (Daemon                *daemon,

                 throw_error (context, ERROR_FAILED, "usermod returned an error: %s", std_err);

                 g_free (std_out);

                 g_free (std_err);

-                g_free (cmdline);

                 return;

         }

         g_free (std_out);

         g_free (std_err);

-        g_free (cmdline);

         if (user->password_mode != PASSWORD_MODE_REGULAR) {

                 user->password_mode = PASSWORD_MODE_REGULAR;

-- 

1.7.0.1