Merge remote-tracking branch 'jwrdecoede/for-keith'

10 files changed, 403 insertions, 37 deletions

diff --git a/hw/xfree86/Makefile.am b/hw/xfree86/Makefile.am
index 73e1b4c1f..a315bbc17 100644
--- a/hw/xfree86/Makefile.am
+++ b/hw/xfree86/Makefile.am
@@ -81,9 +81,15 @@ Xorg_DEPENDENCIES = $(LOCAL_LIBS)
 
 Xorg_LDFLAGS = $(LD_EXPORT_SYMBOLS_FLAG)
 
+if SUID_WRAPPER
+wrapdir = $(SUID_WRAPPER_DIR)
+wrap_PROGRAMS = Xorg.wrap
+Xorg_wrap_SOURCES = xorg-wrapper.c
+endif
+
 BUILT_SOURCES = xorg.conf.example
 DISTCLEANFILES = xorg.conf.example
-EXTRA_DIST = xorgconf.cpp
+EXTRA_DIST = xorgconf.cpp Xorg.sh.in
 
 # Without logdir, X will post an error on the terminal and will not start
 install-data-local:
@@ -98,6 +104,11 @@ if INSTALL_SETUID
 	chown root $(DESTDIR)$(bindir)/Xorg
 	chmod u+s $(DESTDIR)$(bindir)/Xorg
 endif
+if SUID_WRAPPER
+	mv $(DESTDIR)$(bindir)/Xorg $(DESTDIR)$(SUID_WRAPPER_DIR)/Xorg.bin
+	${INSTALL} -m 755 Xorg.sh $(DESTDIR)$(bindir)/Xorg
+	-chown root $(DESTDIR)$(SUID_WRAPPER_DIR)/Xorg.wrap && chmod u+s $(DESTDIR)$(SUID_WRAPPER_DIR)/Xorg.wrap
+endif
 
 uninstall-local:
 if CYGWIN
@@ -119,7 +130,7 @@ xorg.conf.example: xorgconf.cpp
 relink:
 	$(AM_V_at)rm -f Xorg$(EXEEXT) && $(MAKE) Xorg$(EXEEXT)
 
-CLEANFILES = sdksyms.c sdksyms.dep
+CLEANFILES = sdksyms.c sdksyms.dep Xorg.sh
 EXTRA_DIST += sdksyms.sh
 
 sdksyms.dep sdksyms.c: sdksyms.sh
diff --git a/hw/xfree86/Xorg.sh.in b/hw/xfree86/Xorg.sh.in
new file mode 100644
index 000000000..cef4859c8
--- /dev/null
+++ b/hw/xfree86/Xorg.sh.in
@@ -0,0 +1,11 @@
+#!/bin/sh
+#
+# Execute Xorg.wrap if it exists otherwise execute Xorg.bin directly.
+# This allows distros to put the suid wrapper in a separate package.
+
+basedir=@SUID_WRAPPER_DIR@
+if [ -x "$basedir"/Xorg.wrap ]; then
+	exec "$basedir"/Xorg.wrap "$@"
+else
+	exec "$basedir"/Xorg.bin "$@"
+fi
diff --git a/hw/xfree86/common/xf86Xinput.c b/hw/xfree86/common/xf86Xinput.c
index 36b92a9f7..a367ae3cb 100644
--- a/hw/xfree86/common/xf86Xinput.c
+++ b/hw/xfree86/common/xf86Xinput.c
@@ -766,6 +766,11 @@ xf86DeleteInput(InputInfoPtr pInp, int flags)
 
     FreeInputAttributes(pInp->attrs);
 
+    if (pInp->flags & XI86_SERVER_FD) {
+        systemd_logind_release_fd(pInp->major, pInp->minor);
+        close(pInp->fd);
+    }
+
     /* Remove the entry from the list. */
     if (pInp == xf86InputDevs)
         xf86InputDevs = pInp->next;
@@ -779,11 +784,6 @@ xf86DeleteInput(InputInfoPtr pInp, int flags)
         /* Else the entry wasn't in the xf86InputDevs list (ignore this). */
     }
 
-    if (pInp->flags & XI86_SERVER_FD) {
-        systemd_logind_release_fd(pInp->major, pInp->minor);
-        close(pInp->fd);
-    }
-
     free((void *) pInp->driver);
     free((void *) pInp->name);
     xf86optionListFree(pInp->options);
diff --git a/hw/xfree86/common/xf86platformBus.h b/hw/xfree86/common/xf86platformBus.h
index 78b5a5bea..5dee4e0e0 100644
--- a/hw/xfree86/common/xf86platformBus.h
+++ b/hw/xfree86/common/xf86platformBus.h
@@ -54,11 +54,12 @@ xf86_add_platform_device(struct OdevAttributes *attribs, Bool unowned);
 extern int
 xf86_remove_platform_device(int dev_index);
 extern Bool
+xf86_get_platform_device_unowned(int index);
+/* Note starting with xserver 1.16 these 2 functions never fail */
+extern Bool
 xf86_add_platform_device_attrib(int index, int attrib_id, char *attrib_str);
 extern Bool
 xf86_add_platform_device_int_attrib(int index, int attrib_id, int attrib_value);
-extern Bool
-xf86_get_platform_device_unowned(int index);
 
 extern int
 xf86platformAddDevice(int index);
diff --git a/hw/xfree86/man/Makefile.am b/hw/xfree86/man/Makefile.am
index 80e22cbab..f41d26c4e 100644
--- a/hw/xfree86/man/Makefile.am
+++ b/hw/xfree86/man/Makefile.am
@@ -1,3 +1,8 @@
 include $(top_srcdir)/manpages.am
 appman_PRE = Xorg.man
 fileman_PRE = xorg.conf.man xorg.conf.d.man
+
+if SUID_WRAPPER
+appman_PRE += Xorg.wrap.man
+fileman_PRE += Xwrapper.config.man
+endif
diff --git a/hw/xfree86/man/Xorg.wrap.man b/hw/xfree86/man/Xorg.wrap.man
new file mode 100644
index 000000000..f2153e35b
--- /dev/null
+++ b/hw/xfree86/man/Xorg.wrap.man
@@ -0,0 +1,67 @@
+.\" Xwrapper.wrap.1
+.\"
+.\" Copyright 2014 Red Hat, Inc.
+.\"
+.\" Permission to use, copy, modify, distribute, and sell this software and its
+.\" documentation for any purpose is hereby granted without fee, provided that
+.\" the above copyright notice appear in all copies and that both that
+.\" copyright notice and this permission notice appear in supporting
+.\" documentation.
+.\"
+.\" The above copyright notice and this permission notice shall be included
+.\" in all copies or substantial portions of the Software.
+.\"
+.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+.\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+.\" IN NO EVENT SHALL THE OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR
+.\" OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+.\" ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+.\" OTHER DEALINGS IN THE SOFTWARE.
+.\"
+.\" Except as contained in this notice, the name of The Open Group shall
+.\" not be used in advertising or otherwise to promote the sale, use or
+.\" other dealings in this Software without prior written authorization
+.\" from The Open Group.
+.\"
+.\" shorthand for double quote that works everywhere.
+.ds q \N'34'
+.TH Xorg.wrap 1 __xorgversion__
+.SH NAME
+Xorg.wrap \- Xorg X server binary wrapper
+.SH DESCRIPTION
+The Xorg X server may need root rights to function properly. To start the
+Xorg X server with these rights your system is using a suid root wrapper
+installed as __suid_wrapper_dir__/Xorg.wrap which will execute the real
+X server which is installed as __suid_wrapper_dir__/Xorg.bin .
+.PP
+By default Xorg.wrap will autodetect if root rights are necessary, and
+if not it will drop its elevated rights before starting the real X server.
+By default Xorg.wrap will only allow executing the real X server from login
+sessions on a physical console.
+
+.SH CONFIG FILE
+Xorg.wrap's default behavior can be overridden from the
+\fI__sysconfdir__/X11/Xwrapper.config\fP config file. Lines starting with a
+\fB#\fP in Xwrapper.config are considered comments and will be ignored. Any
+other non empty lines must take the form of \fBkey\fP = \fIvalue\fP.
+.TP 8
+\fBallowed_users\fP = \fIrootonly\fP|\fIconsole\fP|\fIanybody\fP
+Specify which users may start the X server through the wrapper. Use
+\fIrootonly\fP to only allow root, use \fIconsole\fP to only allow users
+logged into a physical console, and use \fIanybody\fP to allow anybody.
+The default is \fIconsole\fP.
+.TP 8
+\fBneeds_root_rights\fP = \fIyes\fP|\fIno\fP|\fIauto\fP
+Configure if the wrapper should drop its elevated (root) rights before starting
+the X server. Use \fIyes\fP to force execution as root, \fIno\fP to force
+execution with all suid rights dropped, and \fIauto\fP to letter the wrapper
+auto-detect. The default is \fIauto\fP.
+.PP
+When auto-detecting the wrapper will drop rights if kms graphics are available
+and not drop them if no kms graphics are detected. If a system has multiple
+graphics cards and some are not kms capable auto-detection may fail,
+in this case manual configuration should be used.
+
+.SH "SEE ALSO"
+Xorg X server information: \fIXorg\fP(1)
diff --git a/hw/xfree86/man/Xwrapper.config.man b/hw/xfree86/man/Xwrapper.config.man
new file mode 100644
index 000000000..800947c55
--- /dev/null
+++ b/hw/xfree86/man/Xwrapper.config.man
@@ -0,0 +1 @@
+.so man1/Xorg.wrap.1
diff --git a/hw/xfree86/os-support/linux/lnx_platform.c b/hw/xfree86/os-support/linux/lnx_platform.c
index 109a9a774..dbd7aa0aa 100644
--- a/hw/xfree86/os-support/linux/lnx_platform.c
+++ b/hw/xfree86/os-support/linux/lnx_platform.c
@@ -40,10 +40,7 @@ get_drm_info(struct OdevAttributes *attribs, char *path, int delayed_index)
             systemd_logind_release_fd(major, minor);
             return FALSE;
         }
-        if (!config_odev_add_int_attribute(attribs, ODEV_ATTRIB_FD, fd)) {
-            systemd_logind_release_fd(major, minor);
-            return FALSE;
-        }
+        config_odev_add_int_attribute(attribs, ODEV_ATTRIB_FD, fd);
         server_fd = TRUE;
     }
 
diff --git a/hw/xfree86/os-support/linux/systemd-logind.c b/hw/xfree86/os-support/linux/systemd-logind.c
index a8406d8be..62858b062 100644
--- a/hw/xfree86/os-support/linux/systemd-logind.c
+++ b/hw/xfree86/os-support/linux/systemd-logind.c
@@ -51,11 +51,43 @@ struct systemd_logind_info {
 
 static struct systemd_logind_info logind_info;
 
+static InputInfoPtr
+systemd_logind_find_info_ptr_by_devnum(InputInfoPtr start,
+                                       int major, int minor)
+{
+    InputInfoPtr pInfo;
+
+    for (pInfo = start; pInfo; pInfo = pInfo->next)
+        if (pInfo->major == major && pInfo->minor == minor &&
+                (pInfo->flags & XI86_SERVER_FD))
+            return pInfo;
+
+    return NULL;
+}
+
+static void
+systemd_logind_set_input_fd_for_all_devs(int major, int minor, int fd,
+                                         Bool enable)
+{
+    InputInfoPtr pInfo;
+
+    pInfo = systemd_logind_find_info_ptr_by_devnum(xf86InputDevs, major, minor);
+    while (pInfo) {
+        pInfo->fd = fd;
+        pInfo->options = xf86ReplaceIntOption(pInfo->options, "fd", fd);
+        if (enable)
+            xf86EnableInputDeviceForVTSwitch(pInfo);
+
+        pInfo = systemd_logind_find_info_ptr_by_devnum(pInfo->next, major, minor);
+    }
+}
+
 int
 systemd_logind_take_fd(int _major, int _minor, const char *path,
                        Bool *paused_ret)
 {
     struct systemd_logind_info *info = &logind_info;
+    InputInfoPtr pInfo;
     DBusError error;
     DBusMessage *msg = NULL;
     DBusMessage *reply = NULL;
@@ -71,6 +103,16 @@ systemd_logind_take_fd(int _major, int _minor, const char *path,
     if (strstr(path, "mouse"))
         return -1;
 
+    /* Check if we already have an InputInfo entry with this major, minor
+     * (shared device-nodes happen ie with Wacom tablets). */
+    pInfo = systemd_logind_find_info_ptr_by_devnum(xf86InputDevs, major, minor);
+    if (pInfo) {
+        LogMessage(X_INFO, "systemd-logind: returning pre-existing fd for %s %u:%u\n",
+               path, major, minor);
+        *paused_ret = FALSE;
+        return pInfo->fd;
+    }
+
     dbus_error_init(&error);
 
     msg = dbus_message_new_method_call("org.freedesktop.login1", info->session,
@@ -123,15 +165,31 @@ void
 systemd_logind_release_fd(int _major, int _minor)
 {
     struct systemd_logind_info *info = &logind_info;
+    InputInfoPtr pInfo;
     DBusError error;
     DBusMessage *msg = NULL;
     DBusMessage *reply = NULL;
     dbus_int32_t major = _major;
     dbus_int32_t minor = _minor;
+    int matches = 0;
 
     if (!info->session || major == 0)
         return;
 
+    /* Only release the fd if there is only 1 InputInfo left for this major
+     * and minor, otherwise other InputInfo's are still referencing the fd. */
+    pInfo = systemd_logind_find_info_ptr_by_devnum(xf86InputDevs, major, minor);
+    while (pInfo) {
+        matches++;
+        pInfo = systemd_logind_find_info_ptr_by_devnum(pInfo->next, major, minor);
+    }
+    if (matches > 1) {
+        LogMessage(X_INFO, "systemd-logind: not releasing fd for %u:%u, still in use\n", major, minor);
+        return;
+    }
+
+    LogMessage(X_INFO, "systemd-logind: releasing fd for %u:%u\n", major, minor);
+
     dbus_error_init(&error);
 
     msg = dbus_message_new_method_call("org.freedesktop.login1", info->session,
@@ -203,19 +261,6 @@ systemd_logind_vtenter(void)
     xf86InputEnableVTProbe();
 }
 
-static InputInfoPtr
-systemd_logind_find_info_ptr_by_devnum(int major, int minor)
-{
-    InputInfoPtr pInfo;
-
-    for (pInfo = xf86InputDevs; pInfo; pInfo = pInfo->next)
-        if (pInfo->major == major && pInfo->minor == minor &&
-                (pInfo->flags & XI86_SERVER_FD))
-            return pInfo;
-
-    return NULL;
-}
-
 static void
 systemd_logind_ack_pause(struct systemd_logind_info *info,
                          dbus_int32_t minor, dbus_int32_t major)
@@ -320,7 +365,8 @@ message_filter(DBusConnection * connection, DBusMessage * message, void *data)
 
     pdev = xf86_find_platform_device_by_devnum(major, minor);        
     if (!pdev)
-        pInfo = systemd_logind_find_info_ptr_by_devnum(major, minor);
+        pInfo = systemd_logind_find_info_ptr_by_devnum(xf86InputDevs,
+                                                       major, minor);
     if (!pdev && !pInfo) {
         LogMessage(X_WARNING, "systemd-logind: could not find dev %u:%u\n",
                    major, minor);
@@ -335,8 +381,7 @@ message_filter(DBusConnection * connection, DBusMessage * message, void *data)
             pdev->flags |= XF86_PDEV_PAUSED;
         else {
             close(pInfo->fd);
-            pInfo->fd = -1;
-            pInfo->options = xf86ReplaceIntOption(pInfo->options, "fd", -1);
+            systemd_logind_set_input_fd_for_all_devs(major, minor, -1, FALSE);
         }
         if (ack)
             systemd_logind_ack_pause(info, major, minor);
@@ -345,15 +390,12 @@ message_filter(DBusConnection * connection, DBusMessage * message, void *data)
         /* info->vt_active gets set by systemd_logind_vtenter() */
         info->active = TRUE;
 
-        if (pdev) {
+        if (pdev)
             pdev->flags &= ~XF86_PDEV_PAUSED;
-        }
-        else {
-            pInfo->fd = fd;
-            pInfo->options = xf86ReplaceIntOption(pInfo->options, "fd", fd);
-            if (info->vt_active)
-                xf86EnableInputDeviceForVTSwitch(pInfo);
-        }
+        else
+            systemd_logind_set_input_fd_for_all_devs(major, minor, fd,
+                                                     info->vt_active);
+
         /* Always call vtenter(), in case there are only legacy video devs */
         systemd_logind_vtenter();
     }
diff --git a/hw/xfree86/xorg-wrapper.c b/hw/xfree86/xorg-wrapper.c
new file mode 100644
index 000000000..90c8c11ef
--- /dev/null
+++ b/hw/xfree86/xorg-wrapper.c
@@ -0,0 +1,231 @@
+/*
+ * Copyright © 2014 Red Hat, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Author: Hans de Goede <hdegoede@redhat.com>
+ */
+
+#include "dix-config.h"
+
+#include <fcntl.h>
+#include <limits.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <drm/drm.h>
+#include <xf86drm.h> /* For DRM_DEV_NAME */
+
+#define CONFIG_FILE SYSCONFDIR "/X11/Xwrapper.config"
+
+enum { ROOT_ONLY, CONSOLE_ONLY, ANYBODY };
+
+/* KISS non locale / LANG parsing isspace version */
+static int is_space(char c)
+{
+    return c == ' ' || c == '\t' || c == '\n';
+}
+
+static char *strip(char *s)
+{
+    int i;
+
+    /* Strip leading whitespace */
+    while (s[0] && is_space(s[0]))
+        s++;
+
+    /* Strip trailing whitespace */
+    i = strlen(s) - 1;
+    while (i >= 0 && is_space(s[i])) {
+        s[i] = 0;
+        i--;
+    }
+
+    return s;
+}
+
+static void parse_config(int *allowed, int *needs_root_rights)
+{
+    FILE *f;
+    char buf[1024];
+    char *stripped, *equals, *key, *value;
+    int line = 0;
+
+    f = fopen(CONFIG_FILE, "r");
+    if (!f)
+        return;
+
+    while (fgets(buf, sizeof(buf), f)) {
+        line++;
+
+        /* Skip comments and empty lines */
+        stripped = strip(buf);
+        if (stripped[0] == '#' || stripped[0] == 0)
+            continue;
+
+        /* Split in a key + value pair */
+        equals = strchr(stripped, '=');
+        if (!equals) {
+            fprintf(stderr, "Syntax error at %s line %d\n", CONFIG_FILE, line);
+            exit(1);
+        }
+        *equals = 0;
+        key   = strip(stripped);   /* To remove trailing whitespace from key */
+        value = strip(equals + 1); /* To remove leading whitespace from val */
+        if (!key[0]) {
+            fprintf(stderr, "Missing key at %s line %d\n", CONFIG_FILE, line);
+            exit(1);
+        }
+        if (!value[0]) {
+            fprintf(stderr, "Missing value at %s line %d\n", CONFIG_FILE, line);
+            exit(1);
+        }
+
+        /* And finally process */
+        if (strcmp(key, "allowed_users") == 0) {
+            if (strcmp(value, "rootonly") == 0)
+                *allowed = ROOT_ONLY;
+            else if (strcmp(value, "console") == 0)
+                *allowed = CONSOLE_ONLY;
+            else if (strcmp(value, "anybody") == 0)
+                *allowed = ANYBODY;
+            else {
+                fprintf(stderr,
+                    "Invalid value '%s' for 'allowed_users' at %s line %d\n",
+                    value, CONFIG_FILE, line);
+                exit(1);
+            }
+        }
+        else if (strcmp(key, "needs_root_rights") == 0) {
+            if (strcmp(value, "yes") == 0)
+                *needs_root_rights = 1;
+            else if (strcmp(value, "no") == 0)
+                *needs_root_rights = 0;
+            else if (strcmp(value, "auto") == 0)
+                *needs_root_rights = -1;
+            else {
+                fprintf(stderr,
+                    "Invalid value '%s' for 'needs_root_rights' at %s line %d\n",
+                    value, CONFIG_FILE, line);
+                exit(1);
+            }
+        }
+        else if (strcmp(key, "nice_value") == 0) {
+            /* Backward compatibility with older Debian Xwrapper, ignore */
+        }
+        else {
+            fprintf(stderr, "Invalid key '%s' at %s line %d\n", key,
+                    CONFIG_FILE, line);
+            exit(1);
+        }
+    }
+    fclose(f);
+}
+
+int main(int argc, char *argv[])
+{
+    struct drm_mode_card_res res;
+    struct stat st;
+    char buf[PATH_MAX];
+    int i, r, fd;
+    int kms_cards = 0;
+    int total_cards = 0;
+    int allowed = CONSOLE_ONLY;
+    int needs_root_rights = -1;
+
+    parse_config(&allowed, &needs_root_rights);
+
+    /* For non root users check if they are allowed to run the X server */
+    if (getuid() != 0) {
+        switch (allowed) {
+        case ROOT_ONLY:
+            /* Already checked above */
+            fprintf(stderr, "%s: Only root is allowed to run the X server\n", argv[0]);
+            exit(1);
+            break;
+        case CONSOLE_ONLY:
+            /* Some of stdin / stdout / stderr maybe redirected to a file */
+            for (i = STDIN_FILENO; i <= STDERR_FILENO; i++) {
+                r = fstat(i, &st);
+                if (r == 0 && S_ISCHR(st.st_mode) && major(st.st_rdev) == 4)
+                    break;
+            }
+            if (i > STDERR_FILENO) {
+                fprintf(stderr, "%s: Only console users are allowed to run the X server\n", argv[0]);
+                exit(1);
+            }
+            break;
+        case ANYBODY:
+            break;
+        }
+    }
+
+    /* Detect if we need root rights, except when overriden by the config */
+    if (needs_root_rights == -1) {
+        for (i = 0; i < 16; i++) {
+            snprintf(buf, sizeof(buf), DRM_DEV_NAME, DRM_DIR_NAME, i);
+            fd = open(buf, O_RDWR);
+            if (fd == -1)
+                continue;
+
+            total_cards++;
+
+            memset(&res, 0, sizeof(struct drm_mode_card_res));
+            r = ioctl(fd, DRM_IOCTL_MODE_GETRESOURCES, &res);
+            if (r == 0 && res.count_connectors > 0)
+                kms_cards++;
+
+            close(fd);
+        }
+    }
+
+    /* If we've found cards, and all cards support kms, drop root rights */
+    if (needs_root_rights == 0 || (total_cards && kms_cards == total_cards)) {
+        gid_t realgid = getgid();
+        uid_t realuid = getuid();
+
+        if (setresgid(-1, realgid, realgid) != 0) {
+            perror("Could not drop setgid privileges");
+            exit(1);
+        }
+        if (setresuid(-1, realuid, realuid) != 0) {
+            perror("Could not drop setuid privileges");
+            exit(1);
+        }
+    }
+
+    snprintf(buf, sizeof(buf), "%s/Xorg.bin", SUID_WRAPPER_DIR);
+
+    /* Check if the server is executable by our real uid */
+    if (access(buf, X_OK) != 0) {
+        perror("Missing execute permissions for " SUID_WRAPPER_DIR "Xorg.bin");
+        exit(1);
+    }
+
+    argv[0] = buf;
+    (void) execv(argv[0], argv);
+    perror("Failed to execute " SUID_WRAPPER_DIR "/Xorg.bin");
+    exit(1);
+}