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
  50 static void
  51 die(const char *errstr, ...)
  52 {
  53         va_list ap;
  54
  55         va_start(ap, errstr);
  56         vfprintf(stderr, errstr, ap);
  57         va_end(ap);
  58         exit(1);
  59 }
  60
  61 #ifdef __linux__
  62 #include <fcntl.h>
  63 #include <linux/oom.h>
  64
  65 static void
  66 dontkillme(void)
  67 {
  68         int fd;
  69         int length;
  70         char value[64];
  71
  72         fd = open("/proc/self/oom_score_adj", O_WRONLY);
  73         if (fd < 0 && errno == ENOENT)
  74                 return;
  75
  76         /* convert OOM_SCORE_ADJ_MIN to string for writing */
  77         length = snprintf(value, sizeof(value), "%d\n", OOM_SCORE_ADJ_MIN);
  78
  79         /* bail on truncation */
  80         if (length >= sizeof(value))
  81                 die("buffer too small\n");
  82
  83         if (fd < 0 || write(fd, value, length) != length || close(fd) != 0)
  84                 die("cannot disable the out-of-memory killer for this process (make sure to suid or sgid slock)\n");
  85 }
  86 #endif
  87
  88 #ifndef HAVE_BSD_AUTH
  89 /* only run as root */
  90 static const char *
  91 getpw(void)
  92 {
  93         const char *rval;
  94         struct passwd *pw;
  95
  96         errno = 0;
  97         if (!(pw = getpwuid(getuid()))) {
  98                 if (errno)
  99                         die("slock: getpwuid: %s\n", strerror(errno));
 100                 else
 101                         die("slock: cannot retrieve password entry\n");
 102         }
 103         rval = pw->pw_passwd;
 104
 105 #if HAVE_SHADOW_H
 106         if (rval[0] == 'x' && rval[1] == '\0') {
 107                 struct spwd *sp;
 108                 if (!(sp = getspnam(getenv("USER"))))
 109                         die("slock: cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
 110                 rval = sp->sp_pwdp;
 111         }
 112 #endif
 113
 114         /* drop privileges */
 115         if (geteuid() == 0 &&
 116             ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
 117                 die("slock: cannot drop privileges\n");
 118         return rval;
 119 }
 120 #endif
 121
 122 static void
 123 #ifdef HAVE_BSD_AUTH
 124 readpw(Display *dpy)
 125 #else
 126 readpw(Display *dpy, const char *pws)
 127 #endif
 128 {
 129         char buf[32], passwd[256];
 130         int num, screen;
 131         unsigned int len, color;
 132         KeySym ksym;
 133         XEvent ev;
 134         static int oldc = INIT;
 135
 136         len = 0;
 137         running = True;
 138
 139         /* As "slock" stands for "Simple X display locker", the DPMS settings
 140          * had been removed and you can set it with "xset" or some other
 141          * utility. This way the user can easily set a customized DPMS
 142          * timeout. */
 143         while (running && !XNextEvent(dpy, &ev)) {
 144                 if (ev.type == KeyPress) {
 145                         buf[0] = 0;
 146                         num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0);
 147                         if (IsKeypadKey(ksym)) {
 148                                 if (ksym == XK_KP_Enter)
 149                                         ksym = XK_Return;
 150                                 else if (ksym >= XK_KP_0 && ksym <= XK_KP_9)
 151                                         ksym = (ksym - XK_KP_0) + XK_0;
 152                         }
 153                         if (IsFunctionKey(ksym) ||
 154                             IsKeypadKey(ksym) ||
 155                             IsMiscFunctionKey(ksym) ||
 156                             IsPFKey(ksym) ||
 157                             IsPrivateKeypadKey(ksym))
 158                                 continue;
 159                         switch (ksym) {
 160                         case XK_Return:
 161                                 passwd[len] = 0;
 162 #ifdef HAVE_BSD_AUTH
 163                                 running = !auth_userokay(getlogin(), NULL, "auth-xlock", passwd);
 164 #else
 165                                 running = !!strcmp(crypt(passwd, pws), pws);
 166 #endif
 167                                 if (running) {
 168                                         XBell(dpy, 100);
 169                                         failure = True;
 170                                 }
 171                                 len = 0;
 172                                 break;
 173                         case XK_Escape:
 174                                 len = 0;
 175                                 break;
 176                         case XK_BackSpace:
 177                                 if (len)
 178                                         --len;
 179                                 break;
 180                         default:
 181                                 if (num && !iscntrl((int)buf[0]) && (len + num < sizeof(passwd))) {
 182                                         memcpy(passwd + len, buf, num);
 183                                         len += num;
 184                                 }
 185                                 break;
 186                         }
 187                         color = len ? INPUT : (failure || failonclear ? FAILED : INIT);
 188                         if (running && oldc != color) {
 189                                 for (screen = 0; screen < nscreens; screen++) {
 190                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[color]);
 191                                         XClearWindow(dpy, locks[screen]->win);
 192                                 }
 193                                 oldc = color;
 194                         }
 195                 } else if (rr && ev.type == rrevbase + RRScreenChangeNotify) {
 196                         XRRScreenChangeNotifyEvent *rre = (XRRScreenChangeNotifyEvent*)&ev;
 197                         for (screen = 0; screen < nscreens; screen++) {
 198                                 if (locks[screen]->win == rre->window) {
 199                                         XResizeWindow(dpy, locks[screen]->win, rre->width, rre->height);
 200                                         XClearWindow(dpy, locks[screen]->win);
 201                                 }
 202                         }
 203                 } else for (screen = 0; screen < nscreens; screen++)
 204                         XRaiseWindow(dpy, locks[screen]->win);
 205         }
 206 }
 207
 208 static void
 209 unlockscreen(Display *dpy, Lock *lock)
 210 {
 211         if(dpy == NULL || lock == NULL)
 212                 return;
 213
 214         XUngrabPointer(dpy, CurrentTime);
 215         XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, NUMCOLS, 0);
 216         XFreePixmap(dpy, lock->pmap);
 217         XDestroyWindow(dpy, lock->win);
 218
 219         free(lock);
 220 }
 221
 222 static Lock *
 223 lockscreen(Display *dpy, int screen)
 224 {
 225         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
 226         unsigned int len;
 227         int i;
 228         Lock *lock;
 229         XColor color, dummy;
 230         XSetWindowAttributes wa;
 231         Cursor invisible;
 232
 233         if (!running || dpy == NULL || screen < 0 || !(lock = malloc(sizeof(Lock))))
 234                 return NULL;
 235
 236         lock->screen = screen;
 237         lock->root = RootWindow(dpy, lock->screen);
 238
 239         for (i = 0; i < NUMCOLS; i++) {
 240                 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), colorname[i], &color, &dummy);
 241                 lock->colors[i] = color.pixel;
 242         }
 243
 244         /* init */
 245         wa.override_redirect = 1;
 246         wa.background_pixel = lock->colors[INIT];
 247         lock->win = XCreateWindow(dpy, lock->root, 0, 0, DisplayWidth(dpy, lock->screen), DisplayHeight(dpy, lock->screen),
 248                                   0, DefaultDepth(dpy, lock->screen), CopyFromParent,
 249                                   DefaultVisual(dpy, lock->screen), CWOverrideRedirect | CWBackPixel, &wa);
 250         lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
 251         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
 252         XDefineCursor(dpy, lock->win, invisible);
 253         XMapRaised(dpy, lock->win);
 254         if (rr)
 255                 XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
 256
 257         /* Try to grab mouse pointer *and* keyboard, else fail the lock */
 258         for (len = 1000; len; len--) {
 259                 if (XGrabPointer(dpy, lock->root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
 260                     GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
 261                         break;
 262                 usleep(1000);
 263         }
 264         if (!len) {
 265                 fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n", screen);
 266         } else {
 267                 for (len = 1000; len; len--) {
 268                         if (XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync, CurrentTime) == GrabSuccess) {
 269                                 /* everything fine, we grabbed both inputs */
 270                                 XSelectInput(dpy, lock->root, SubstructureNotifyMask);
 271                                 return lock;
 272                         }
 273                         usleep(1000);
 274                 }
 275                 fprintf(stderr, "slock: unable to grab keyboard for screen %d\n", screen);
 276         }
 277         /* grabbing one of the inputs failed */
 278         running = 0;
 279         unlockscreen(dpy, lock);
 280         return NULL;
 281 }
 282
 283 static void
 284 usage(void)
 285 {
 286         fprintf(stderr, "usage: slock [-v|POST_LOCK_CMD]\n");
 287         exit(1);
 288 }
 289
 290 int
 291 main(int argc, char **argv) {
 292 #ifndef HAVE_BSD_AUTH
 293         const char *pws;
 294 #endif
 295         Display *dpy;
 296         int screen;
 297
 298         if ((argc == 2) && !strcmp("-v", argv[1]))
 299                 die("slock-%s, © 2006-2016 slock engineers\n", VERSION);
 300
 301         if ((argc == 2) && !strcmp("-h", argv[1]))
 302                 usage();
 303
 304 #ifdef __linux__
 305         dontkillme();
 306 #endif
 307
 308         if (!getpwuid(getuid()))
 309                 die("slock: no passwd entry for you\n");
 310
 311 #ifndef HAVE_BSD_AUTH
 312         pws = getpw();
 313 #endif
 314
 315         if (!(dpy = XOpenDisplay(0)))
 316                 die("slock: cannot open display\n");
 317         rr = XRRQueryExtension(dpy, &rrevbase, &rrerrbase);
 318         /* Get the number of screens in display "dpy" and blank them all. */
 319         nscreens = ScreenCount(dpy);
 320         if (!(locks = malloc(sizeof(Lock*) * nscreens)))
 321                 die("slock: malloc: %s\n", strerror(errno));
 322         int nlocks = 0;
 323         for (screen = 0; screen < nscreens; screen++) {
 324                 if ((locks[screen] = lockscreen(dpy, screen)) != NULL)
 325                         nlocks++;
 326         }
 327         XSync(dpy, False);
 328
 329         /* Did we actually manage to lock something? */
 330         if (nlocks == 0) { /* nothing to protect */
 331                 free(locks);
 332                 XCloseDisplay(dpy);
 333                 return 1;
 334         }
 335
 336         if (argc >= 2 && fork() == 0) {
 337                 if (dpy)
 338                         close(ConnectionNumber(dpy));
 339                 execvp(argv[1], argv+1);
 340                 die("slock: execvp %s failed: %s\n", argv[1], strerror(errno));
 341         }
 342
 343         /* Everything is now blank. Now wait for the correct password. */
 344 #ifdef HAVE_BSD_AUTH
 345         readpw(dpy);
 346 #else
 347         readpw(dpy, pws);
 348 #endif
 349
 350         /* Password ok, unlock everything and quit. */
 351         for (screen = 0; screen < nscreens; screen++)
 352                 unlockscreen(dpy, locks[screen]);
 353
 354         free(locks);
 355         XCloseDisplay(dpy);
 356
 357         return 0;
 358 }