slock.c

   1 /* See LICENSE file for license details. */
   2 #define _XOPEN_SOURCE 500
   3 #if HAVE_SHADOW_H
   4 #include <shadow.h>
   5 #endif
   6
   7 #include <ctype.h>
   8 #include <errno.h>
   9 #include <pwd.h>
  10 #include <stdarg.h>
  11 #include <stdlib.h>
  12 #include <stdio.h>
  13 #include <string.h>
  14 #include <unistd.h>
  15 #include <sys/types.h>
  16 #include <X11/extensions/Xrandr.h>
  17 #include <X11/keysym.h>
  18 #include <X11/Xlib.h>
  19 #include <X11/Xutil.h>
  20
  21 #if HAVE_BSD_AUTH
  22 #include <login_cap.h>
  23 #include <bsd_auth.h>
  24 #endif
  25
  26 enum {
  27         INIT,
  28         INPUT,
  29         FAILED,
  30         NUMCOLS
  31 };
  32
  33 #include "config.h"
  34
  35 typedef struct {
  36         int screen;
  37         Window root, win;
  38         Pixmap pmap;
  39         unsigned long colors[NUMCOLS];
  40 } Lock;
  41
  42 static Lock **locks;
  43 static int nscreens;
  44 static Bool running = True;
  45 static Bool failure = False;
  46 static Bool rr;
  47 static int rrevbase;
  48 static int rrerrbase;
  49 static char *argv0;
  50
  51 static void
  52 die(const char *errstr, ...)
  53 {
  54         va_list ap;
  55
  56         va_start(ap, errstr);
  57         fprintf(stderr, "%s: ", argv0);
  58         vfprintf(stderr, errstr, ap);
  59         va_end(ap);
  60         exit(1);
  61 }
  62
  63 #ifdef __linux__
  64 #include <fcntl.h>
  65
  66 static void
  67 dontkillme(void)
  68 {
  69         int fd;
  70
  71         fd = open("/proc/self/oom_score_adj", O_WRONLY);
  72         if (fd < 0 && errno == ENOENT) {
  73                 return;
  74         }
  75         if (fd < 0 || write(fd, "-1000\n", (sizeof("-1000\n") - 1)) !=
  76             (sizeof("-1000\n") - 1) || close(fd) != 0) {
  77                 die("can't tame the oom-killer. is suid or sgid set?\n");
  78         }
  79 }
  80 #endif
  81
  82 #ifndef HAVE_BSD_AUTH
  83 /* only run as root */
  84 static const char *
  85 getpw(void)
  86 {
  87         const char *rval;
  88         struct passwd *pw;
  89
  90         errno = 0;
  91         if (!(pw = getpwuid(getuid()))) {
  92                 if (errno)
  93                         die("getpwuid: %s\n", strerror(errno));
  94                 else
  95                         die("cannot retrieve password entry\n");
  96         }
  97         rval = pw->pw_passwd;
  98
  99 #if HAVE_SHADOW_H
 100         if (rval[0] == 'x' && rval[1] == '\0') {
 101                 struct spwd *sp;
 102                 if (!(sp = getspnam(getenv("USER"))))
 103                         die("cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
 104                 rval = sp->sp_pwdp;
 105         }
 106 #endif
 107
 108         /* drop privileges */
 109         if (geteuid() == 0 &&
 110             ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
 111                 die("cannot drop privileges\n");
 112         return rval;
 113 }
 114 #endif
 115
 116 static void
 117 #ifdef HAVE_BSD_AUTH
 118 readpw(Display *dpy)
 119 #else
 120 readpw(Display *dpy, const char *pws)
 121 #endif
 122 {
 123         char buf[32], passwd[256];
 124         int num, screen;
 125         unsigned int len, color;
 126         KeySym ksym;
 127         XEvent ev;
 128         static int oldc = INIT;
 129
 130         len = 0;
 131         running = True;
 132
 133         /* As "slock" stands for "Simple X display locker", the DPMS settings
 134          * had been removed and you can set it with "xset" or some other
 135          * utility. This way the user can easily set a customized DPMS
 136          * timeout. */
 137         while (running && !XNextEvent(dpy, &ev)) {
 138                 if (ev.type == KeyPress) {
 139                         buf[0] = 0;
 140                         num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0);
 141                         if (IsKeypadKey(ksym)) {
 142                                 if (ksym == XK_KP_Enter)
 143                                         ksym = XK_Return;
 144                                 else if (ksym >= XK_KP_0 && ksym <= XK_KP_9)
 145                                         ksym = (ksym - XK_KP_0) + XK_0;
 146                         }
 147                         if (IsFunctionKey(ksym) ||
 148                             IsKeypadKey(ksym) ||
 149                             IsMiscFunctionKey(ksym) ||
 150                             IsPFKey(ksym) ||
 151                             IsPrivateKeypadKey(ksym))
 152                                 continue;
 153                         switch (ksym) {
 154                         case XK_Return:
 155                                 passwd[len] = 0;
 156 #ifdef HAVE_BSD_AUTH
 157                                 running = !auth_userokay(getlogin(), NULL, "auth-xlock", passwd);
 158 #else
 159                                 running = !!strcmp(crypt(passwd, pws), pws);
 160 #endif
 161                                 if (running) {
 162                                         XBell(dpy, 100);
 163                                         failure = True;
 164                                 }
 165                                 len = 0;
 166                                 break;
 167                         case XK_Escape:
 168                                 len = 0;
 169                                 break;
 170                         case XK_BackSpace:
 171                                 if (len)
 172                                         --len;
 173                                 break;
 174                         default:
 175                                 if (num && !iscntrl((int)buf[0]) && (len + num < sizeof(passwd))) {
 176                                         memcpy(passwd + len, buf, num);
 177                                         len += num;
 178                                 }
 179                                 break;
 180                         }
 181                         color = len ? INPUT : (failure || failonclear ? FAILED : INIT);
 182                         if (running && oldc != color) {
 183                                 for (screen = 0; screen < nscreens; screen++) {
 184                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[color]);
 185                                         XClearWindow(dpy, locks[screen]->win);
 186                                 }
 187                                 oldc = color;
 188                         }
 189                 } else if (rr && ev.type == rrevbase + RRScreenChangeNotify) {
 190                         XRRScreenChangeNotifyEvent *rre = (XRRScreenChangeNotifyEvent*)&ev;
 191                         for (screen = 0; screen < nscreens; screen++) {
 192                                 if (locks[screen]->win == rre->window) {
 193                                         XResizeWindow(dpy, locks[screen]->win, rre->width, rre->height);
 194                                         XClearWindow(dpy, locks[screen]->win);
 195                                 }
 196                         }
 197                 } else for (screen = 0; screen < nscreens; screen++)
 198                         XRaiseWindow(dpy, locks[screen]->win);
 199         }
 200 }
 201
 202 static void
 203 unlockscreen(Display *dpy, Lock *lock)
 204 {
 205         if(dpy == NULL || lock == NULL)
 206                 return;
 207
 208         XUngrabPointer(dpy, CurrentTime);
 209         XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, NUMCOLS, 0);
 210         XFreePixmap(dpy, lock->pmap);
 211         XDestroyWindow(dpy, lock->win);
 212
 213         free(lock);
 214 }
 215
 216 static Lock *
 217 lockscreen(Display *dpy, int screen)
 218 {
 219         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
 220         unsigned int len;
 221         int i;
 222         Lock *lock;
 223         XColor color, dummy;
 224         XSetWindowAttributes wa;
 225         Cursor invisible;
 226
 227         if (!running || dpy == NULL || screen < 0 || !(lock = malloc(sizeof(Lock))))
 228                 return NULL;
 229
 230         lock->screen = screen;
 231         lock->root = RootWindow(dpy, lock->screen);
 232
 233         for (i = 0; i < NUMCOLS; i++) {
 234                 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), colorname[i], &color, &dummy);
 235                 lock->colors[i] = color.pixel;
 236         }
 237
 238         /* init */
 239         wa.override_redirect = 1;
 240         wa.background_pixel = lock->colors[INIT];
 241         lock->win = XCreateWindow(dpy, lock->root, 0, 0, DisplayWidth(dpy, lock->screen), DisplayHeight(dpy, lock->screen),
 242                                   0, DefaultDepth(dpy, lock->screen), CopyFromParent,
 243                                   DefaultVisual(dpy, lock->screen), CWOverrideRedirect | CWBackPixel, &wa);
 244         lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
 245         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
 246         XDefineCursor(dpy, lock->win, invisible);
 247         XMapRaised(dpy, lock->win);
 248         if (rr)
 249                 XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
 250
 251         /* Try to grab mouse pointer *and* keyboard, else fail the lock */
 252         for (len = 1000; len; len--) {
 253                 if (XGrabPointer(dpy, lock->root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
 254                     GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
 255                         break;
 256                 usleep(1000);
 257         }
 258         if (!len) {
 259                 fprintf(stderr, "unable to grab mouse pointer for screen %d\n", screen);
 260         } else {
 261                 for (len = 1000; len; len--) {
 262                         if (XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync, CurrentTime) == GrabSuccess) {
 263                                 /* everything fine, we grabbed both inputs */
 264                                 XSelectInput(dpy, lock->root, SubstructureNotifyMask);
 265                                 return lock;
 266                         }
 267                         usleep(1000);
 268                 }
 269                 fprintf(stderr, "unable to grab keyboard for screen %d\n", screen);
 270         }
 271         /* grabbing one of the inputs failed */
 272         running = 0;
 273         unlockscreen(dpy, lock);
 274         return NULL;
 275 }
 276
 277 int
 278 main(int argc, char **argv)
 279 {
 280 #ifndef HAVE_BSD_AUTH
 281         const char *pws;
 282 #endif
 283         Display *dpy;
 284         int screen;
 285
 286         argv0 = argv[0], argc--, argv++;
 287
 288 #ifdef __linux__
 289         dontkillme();
 290 #endif
 291
 292         if (!getpwuid(getuid()))
 293                 die("no passwd entry for you\n");
 294
 295 #ifndef HAVE_BSD_AUTH
 296         pws = getpw();
 297 #endif
 298
 299         if (!(dpy = XOpenDisplay(0)))
 300                 die("cannot open display\n");
 301         rr = XRRQueryExtension(dpy, &rrevbase, &rrerrbase);
 302         /* Get the number of screens in display "dpy" and blank them all. */
 303         nscreens = ScreenCount(dpy);
 304         if (!(locks = malloc(sizeof(Lock*) * nscreens)))
 305                 die("Out of memory.\n");
 306         int nlocks = 0;
 307         for (screen = 0; screen < nscreens; screen++) {
 308                 if ((locks[screen] = lockscreen(dpy, screen)) != NULL)
 309                         nlocks++;
 310         }
 311         XSync(dpy, False);
 312
 313         /* Did we actually manage to lock something? */
 314         if (nlocks == 0) { /* nothing to protect */
 315                 free(locks);
 316                 XCloseDisplay(dpy);
 317                 return 1;
 318         }
 319
 320         if (argc >= 1 && fork() == 0) {
 321                 if (dpy)
 322                         close(ConnectionNumber(dpy));
 323                 execvp(argv[0], argv);
 324                 die("execvp %s failed: %s\n", argv[0], strerror(errno));
 325         }
 326
 327         /* Everything is now blank. Now wait for the correct password. */
 328 #ifdef HAVE_BSD_AUTH
 329         readpw(dpy);
 330 #else
 331         readpw(dpy, pws);
 332 #endif
 333
 334         /* Password ok, unlock everything and quit. */
 335         for (screen = 0; screen < nscreens; screen++)
 336                 unlockscreen(dpy, locks[screen]);
 337
 338         free(locks);
 339         XCloseDisplay(dpy);
 340
 341         return 0;
 342 }