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\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         pw = getpwuid(getuid());
  98         if (!pw) {
  99                 if (errno)
 100                         die("slock: getpwuid: %s\n", strerror(errno));
 101                 else
 102                         die("slock: cannot retrieve password entry\n");
 103         }
 104         rval =  pw->pw_passwd;
 105
 106 #if HAVE_SHADOW_H
 107         if (rval[0] == 'x' && rval[1] == '\0') {
 108                 struct spwd *sp;
 109                 sp = getspnam(getenv("USER"));
 110                 if (!sp)
 111                         die("slock: cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
 112                 rval = sp->sp_pwdp;
 113         }
 114 #endif
 115
 116         /* drop privileges */
 117         if (geteuid() == 0 &&
 118             ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
 119                 die("slock: cannot drop privileges\n");
 120         return rval;
 121 }
 122 #endif
 123
 124 static void
 125 #ifdef HAVE_BSD_AUTH
 126 readpw(Display *dpy)
 127 #else
 128 readpw(Display *dpy, const char *pws)
 129 #endif
 130 {
 131         char buf[32], passwd[256];
 132         int num, screen;
 133         unsigned int len, color;
 134         KeySym ksym;
 135         XEvent ev;
 136         static int oldc = INIT;
 137
 138         len = 0;
 139         running = True;
 140
 141         /* As "slock" stands for "Simple X display locker", the DPMS settings
 142          * had been removed and you can set it with "xset" or some other
 143          * utility. This way the user can easily set a customized DPMS
 144          * timeout. */
 145         while (running && !XNextEvent(dpy, &ev)) {
 146                 if (ev.type == KeyPress) {
 147                         buf[0] = 0;
 148                         num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0);
 149                         if (IsKeypadKey(ksym)) {
 150                                 if (ksym == XK_KP_Enter)
 151                                         ksym = XK_Return;
 152                                 else if (ksym >= XK_KP_0 && ksym <= XK_KP_9)
 153                                         ksym = (ksym - XK_KP_0) + XK_0;
 154                         }
 155                         if (IsFunctionKey(ksym) ||
 156                             IsKeypadKey(ksym) ||
 157                             IsMiscFunctionKey(ksym) ||
 158                             IsPFKey(ksym) ||
 159                             IsPrivateKeypadKey(ksym))
 160                                 continue;
 161                         switch (ksym) {
 162                         case XK_Return:
 163                                 passwd[len] = 0;
 164 #ifdef HAVE_BSD_AUTH
 165                                 running = !auth_userokay(getlogin(), NULL, "auth-xlock", passwd);
 166 #else
 167                                 running = !!strcmp(crypt(passwd, pws), pws);
 168 #endif
 169                                 if (running) {
 170                                         XBell(dpy, 100);
 171                                         failure = True;
 172                                 }
 173                                 len = 0;
 174                                 break;
 175                         case XK_Escape:
 176                                 len = 0;
 177                                 break;
 178                         case XK_BackSpace:
 179                                 if (len)
 180                                         --len;
 181                                 break;
 182                         default:
 183                                 if (num && !iscntrl((int) buf[0]) && (len + num < sizeof(passwd))) {
 184                                         memcpy(passwd + len, buf, num);
 185                                         len += num;
 186                                 }
 187                                 break;
 188                         }
 189                         color = len ? INPUT : (failure || failonclear ? FAILED : INIT);
 190                         if (running && oldc != color) {
 191                                 for (screen = 0; screen < nscreens; screen++) {
 192                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[color]);
 193                                         XClearWindow(dpy, locks[screen]->win);
 194                                 }
 195                                 oldc = color;
 196                         }
 197                 } else if (rr && ev.type == rrevbase + RRScreenChangeNotify) {
 198                         XRRScreenChangeNotifyEvent *rre = (XRRScreenChangeNotifyEvent*)&ev;
 199                         for (screen = 0; screen < nscreens; screen++) {
 200                                 if (locks[screen]->win == rre->window) {
 201                                         XResizeWindow(dpy, locks[screen]->win, rre->width, rre->height);
 202                                         XClearWindow(dpy, locks[screen]->win);
 203                                 }
 204                         }
 205                 } else for (screen = 0; screen < nscreens; screen++)
 206                         XRaiseWindow(dpy, locks[screen]->win);
 207         }
 208 }
 209
 210 static void
 211 unlockscreen(Display *dpy, Lock *lock)
 212 {
 213         if(dpy == NULL || lock == NULL)
 214                 return;
 215
 216         XUngrabPointer(dpy, CurrentTime);
 217         XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, NUMCOLS, 0);
 218         XFreePixmap(dpy, lock->pmap);
 219         XDestroyWindow(dpy, lock->win);
 220
 221         free(lock);
 222 }
 223
 224 static Lock *
 225 lockscreen(Display *dpy, int screen)
 226 {
 227         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
 228         unsigned int len;
 229         int i;
 230         Lock *lock;
 231         XColor color, dummy;
 232         XSetWindowAttributes wa;
 233         Cursor invisible;
 234
 235         if (dpy == NULL || screen < 0)
 236                 return NULL;
 237
 238         lock = malloc(sizeof(Lock));
 239         if (lock == NULL)
 240                 return NULL;
 241
 242         lock->screen = screen;
 243
 244         lock->root = RootWindow(dpy, lock->screen);
 245
 246         for (i = 0; i < NUMCOLS; i++) {
 247                 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), colorname[i], &color, &dummy);
 248                 lock->colors[i] = color.pixel;
 249         }
 250
 251         /* init */
 252         wa.override_redirect = 1;
 253         wa.background_pixel = lock->colors[INIT];
 254         lock->win = XCreateWindow(dpy, lock->root, 0, 0, DisplayWidth(dpy, lock->screen), DisplayHeight(dpy, lock->screen),
 255                                   0, DefaultDepth(dpy, lock->screen), CopyFromParent,
 256                                   DefaultVisual(dpy, lock->screen), CWOverrideRedirect | CWBackPixel, &wa);
 257         lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
 258         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
 259         XDefineCursor(dpy, lock->win, invisible);
 260         XMapRaised(dpy, lock->win);
 261         if (rr)
 262                 XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
 263         for (len = 1000; len; len--) {
 264                 if (XGrabPointer(dpy, lock->root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
 265                     GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
 266                         break;
 267                 usleep(1000);
 268         }
 269         if (running && (len > 0)) {
 270                 for (len = 1000; len; len--) {
 271                         if (XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync, CurrentTime) == GrabSuccess)
 272                                 break;
 273                         usleep(1000);
 274                 }
 275         }
 276
 277         running &= (len > 0);
 278         if (!running) {
 279                 unlockscreen(dpy, lock);
 280                 lock = NULL;
 281         }
 282         else {
 283                 XSelectInput(dpy, lock->root, SubstructureNotifyMask);
 284         }
 285
 286         return lock;
 287 }
 288
 289 static void
 290 usage(void)
 291 {
 292         fprintf(stderr, "usage: slock [-v|POST_LOCK_CMD]\n");
 293         exit(1);
 294 }
 295
 296 int
 297 main(int argc, char **argv) {
 298 #ifndef HAVE_BSD_AUTH
 299         const char *pws;
 300 #endif
 301         Display *dpy;
 302         int screen;
 303
 304         if ((argc == 2) && !strcmp("-v", argv[1]))
 305                 die("slock-%s, © 2006-2015 slock engineers\n", VERSION);
 306
 307         if ((argc == 2) && !strcmp("-h", argv[1]))
 308                 usage();
 309
 310 #ifdef __linux__
 311         dontkillme();
 312 #endif
 313
 314         if (!getpwuid(getuid()))
 315                 die("slock: no passwd entry for you\n");
 316
 317 #ifndef HAVE_BSD_AUTH
 318         pws = getpw();
 319 #endif
 320
 321         if (!(dpy = XOpenDisplay(0)))
 322                 die("slock: cannot open display\n");
 323         rr = XRRQueryExtension(dpy, &rrevbase, &rrerrbase);
 324         /* Get the number of screens in display "dpy" and blank them all. */
 325         nscreens = ScreenCount(dpy);
 326         locks = malloc(sizeof(Lock *) * nscreens);
 327         if (locks == NULL)
 328                 die("slock: malloc: %s\n", strerror(errno));
 329         int nlocks = 0;
 330         for (screen = 0; screen < nscreens; screen++) {
 331                 if ( (locks[screen] = lockscreen(dpy, screen)) != NULL)
 332                         nlocks++;
 333         }
 334         XSync(dpy, False);
 335
 336         /* Did we actually manage to lock something? */
 337         if (nlocks == 0) { /* nothing to protect */
 338                 free(locks);
 339                 XCloseDisplay(dpy);
 340                 return 1;
 341         }
 342
 343         if (argc >= 2 && fork() == 0) {
 344                 if (dpy)
 345                         close(ConnectionNumber(dpy));
 346                 execvp(argv[1], argv+1);
 347                 die("slock: execvp %s failed: %s\n", argv[1], strerror(errno));
 348         }
 349
 350         /* Everything is now blank. Now wait for the correct password. */
 351 #ifdef HAVE_BSD_AUTH
 352         readpw(dpy);
 353 #else
 354         readpw(dpy, pws);
 355 #endif
 356
 357         /* Password ok, unlock everything and quit. */
 358         for (screen = 0; screen < nscreens; screen++)
 359                 unlockscreen(dpy, locks[screen]);
 360
 361         free(locks);
 362         XCloseDisplay(dpy);
 363
 364         return 0;
 365 }