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 #include "util.h"
  27
  28 enum {
  29         INIT,
  30         INPUT,
  31         FAILED,
  32         NUMCOLS
  33 };
  34
  35 #include "config.h"
  36
  37 typedef struct {
  38         int screen;
  39         Window root, win;
  40         Pixmap pmap;
  41         unsigned long colors[NUMCOLS];
  42 } Lock;
  43
  44 static Lock **locks;
  45 static int nscreens;
  46 static Bool running = True;
  47 static Bool failure = False;
  48 static Bool rr;
  49 static int rrevbase;
  50 static int rrerrbase;
  51
  52 static void
  53 die(const char *errstr, ...)
  54 {
  55         va_list ap;
  56
  57         fputs("slock: ", stderr);
  58         va_start(ap, errstr);
  59         vfprintf(stderr, errstr, ap);
  60         va_end(ap);
  61         exit(1);
  62 }
  63
  64 #ifdef __linux__
  65 #include <fcntl.h>
  66
  67 static void
  68 dontkillme(void)
  69 {
  70         int fd;
  71
  72         fd = open("/proc/self/oom_score_adj", O_WRONLY);
  73         if (fd < 0 && errno == ENOENT) {
  74                 return;
  75         }
  76         if (fd < 0 || write(fd, "-1000\n", (sizeof("-1000\n") - 1)) !=
  77             (sizeof("-1000\n") - 1) || close(fd) != 0) {
  78                 die("can't tame the oom-killer. is suid or sgid set?\n");
  79         }
  80 }
  81 #endif
  82
  83 #ifndef HAVE_BSD_AUTH
  84 /* only run as root */
  85 static const char *
  86 getpw(void)
  87 {
  88         const char *rval;
  89         struct passwd *pw;
  90
  91         errno = 0;
  92         if (!(pw = getpwuid(getuid()))) {
  93                 if (errno)
  94                         die("getpwuid: %s\n", strerror(errno));
  95                 else
  96                         die("cannot retrieve password entry\n");
  97         }
  98         rval = pw->pw_passwd;
  99
 100 #if HAVE_SHADOW_H
 101         if (rval[0] == 'x' && rval[1] == '\0') {
 102                 struct spwd *sp;
 103                 if (!(sp = getspnam(getenv("USER"))))
 104                         die("cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
 105                 rval = sp->sp_pwdp;
 106         }
 107 #endif
 108
 109         /* drop privileges */
 110         if (geteuid() == 0 &&
 111             ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
 112                 die("cannot drop privileges\n");
 113         return rval;
 114 }
 115 #endif
 116
 117 static void
 118 #ifdef HAVE_BSD_AUTH
 119 readpw(Display *dpy)
 120 #else
 121 readpw(Display *dpy, const char *pws)
 122 #endif
 123 {
 124         char buf[32], passwd[256];
 125         int num, screen;
 126         unsigned int len, color;
 127         KeySym ksym;
 128         XEvent ev;
 129         static int oldc = INIT;
 130
 131         len = 0;
 132         running = True;
 133
 134         /* As "slock" stands for "Simple X display locker", the DPMS settings
 135          * had been removed and you can set it with "xset" or some other
 136          * utility. This way the user can easily set a customized DPMS
 137          * timeout. */
 138         while (running && !XNextEvent(dpy, &ev)) {
 139                 if (ev.type == KeyPress) {
 140                         explicit_bzero(&buf, sizeof(buf));
 141                         num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0);
 142                         if (IsKeypadKey(ksym)) {
 143                                 if (ksym == XK_KP_Enter)
 144                                         ksym = XK_Return;
 145                                 else if (ksym >= XK_KP_0 && ksym <= XK_KP_9)
 146                                         ksym = (ksym - XK_KP_0) + XK_0;
 147                         }
 148                         if (IsFunctionKey(ksym) ||
 149                             IsKeypadKey(ksym) ||
 150                             IsMiscFunctionKey(ksym) ||
 151                             IsPFKey(ksym) ||
 152                             IsPrivateKeypadKey(ksym))
 153                                 continue;
 154                         switch (ksym) {
 155                         case XK_Return:
 156                                 passwd[len] = 0;
 157 #ifdef HAVE_BSD_AUTH
 158                                 running = !auth_userokay(getlogin(), NULL, "auth-xlock", passwd);
 159 #else
 160                                 running = !!strcmp(crypt(passwd, pws), pws);
 161 #endif
 162                                 if (running) {
 163                                         XBell(dpy, 100);
 164                                         failure = True;
 165                                 }
 166                                 explicit_bzero(&passwd, sizeof(passwd));
 167                                 len = 0;
 168                                 break;
 169                         case XK_Escape:
 170                                 explicit_bzero(&passwd, sizeof(passwd));
 171                                 len = 0;
 172                                 break;
 173                         case XK_BackSpace:
 174                                 if (len)
 175                                         passwd[len--] = 0;
 176                                 break;
 177                         default:
 178                                 if (num && !iscntrl((int)buf[0]) && (len + num < sizeof(passwd))) {
 179                                         memcpy(passwd + len, buf, num);
 180                                         len += num;
 181                                 }
 182                                 break;
 183                         }
 184                         color = len ? INPUT : (failure || failonclear ? FAILED : INIT);
 185                         if (running && oldc != color) {
 186                                 for (screen = 0; screen < nscreens; screen++) {
 187                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[color]);
 188                                         XClearWindow(dpy, locks[screen]->win);
 189                                 }
 190                                 oldc = color;
 191                         }
 192                 } else if (rr && ev.type == rrevbase + RRScreenChangeNotify) {
 193                         XRRScreenChangeNotifyEvent *rre = (XRRScreenChangeNotifyEvent*)&ev;
 194                         for (screen = 0; screen < nscreens; screen++) {
 195                                 if (locks[screen]->win == rre->window) {
 196                                         XResizeWindow(dpy, locks[screen]->win, rre->width, rre->height);
 197                                         XClearWindow(dpy, locks[screen]->win);
 198                                 }
 199                         }
 200                 } else for (screen = 0; screen < nscreens; screen++)
 201                         XRaiseWindow(dpy, locks[screen]->win);
 202         }
 203 }
 204
 205 static void
 206 unlockscreen(Display *dpy, Lock *lock)
 207 {
 208         if(dpy == NULL || lock == NULL)
 209                 return;
 210
 211         XUngrabPointer(dpy, CurrentTime);
 212         XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, NUMCOLS, 0);
 213         XFreePixmap(dpy, lock->pmap);
 214         XDestroyWindow(dpy, lock->win);
 215
 216         free(lock);
 217 }
 218
 219 static Lock *
 220 lockscreen(Display *dpy, int screen)
 221 {
 222         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
 223         unsigned int len;
 224         int i;
 225         Lock *lock;
 226         XColor color, dummy;
 227         XSetWindowAttributes wa;
 228         Cursor invisible;
 229
 230         if (!running || dpy == NULL || screen < 0 || !(lock = malloc(sizeof(Lock))))
 231                 return NULL;
 232
 233         lock->screen = screen;
 234         lock->root = RootWindow(dpy, lock->screen);
 235
 236         for (i = 0; i < NUMCOLS; i++) {
 237                 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), colorname[i], &color, &dummy);
 238                 lock->colors[i] = color.pixel;
 239         }
 240
 241         /* init */
 242         wa.override_redirect = 1;
 243         wa.background_pixel = lock->colors[INIT];
 244         lock->win = XCreateWindow(dpy, lock->root, 0, 0, DisplayWidth(dpy, lock->screen), DisplayHeight(dpy, lock->screen),
 245                                   0, DefaultDepth(dpy, lock->screen), CopyFromParent,
 246                                   DefaultVisual(dpy, lock->screen), CWOverrideRedirect | CWBackPixel, &wa);
 247         lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
 248         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
 249         XDefineCursor(dpy, lock->win, invisible);
 250         XMapRaised(dpy, lock->win);
 251         if (rr)
 252                 XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
 253
 254         /* Try to grab mouse pointer *and* keyboard, else fail the lock */
 255         for (len = 1000; len; len--) {
 256                 if (XGrabPointer(dpy, lock->root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
 257                     GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
 258                         break;
 259                 usleep(1000);
 260         }
 261         if (!len) {
 262                 fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n", screen);
 263         } else {
 264                 for (len = 1000; len; len--) {
 265                         if (XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync, CurrentTime) == GrabSuccess) {
 266                                 /* everything fine, we grabbed both inputs */
 267                                 XSelectInput(dpy, lock->root, SubstructureNotifyMask);
 268                                 return lock;
 269                         }
 270                         usleep(1000);
 271                 }
 272                 fprintf(stderr, "slock: unable to grab keyboard for screen %d\n", screen);
 273         }
 274         /* grabbing one of the inputs failed */
 275         running = 0;
 276         unlockscreen(dpy, lock);
 277         return NULL;
 278 }
 279
 280 static void
 281 usage(void)
 282 {
 283         fprintf(stderr, "usage: slock [-v|POST_LOCK_CMD]\n");
 284         exit(1);
 285 }
 286
 287 int
 288 main(int argc, char **argv) {
 289 #ifndef HAVE_BSD_AUTH
 290         const char *pws;
 291 #endif
 292         Display *dpy;
 293         int screen;
 294
 295         if ((argc >= 2) && !strcmp("-v", argv[1]))
 296                 die("version %s, © 2006-2016 slock engineers\n", VERSION);
 297
 298         /* treat first argument starting with a '-' as option */
 299         if ((argc >= 2) && argv[1][0] == '-')
 300                 usage();
 301
 302 #ifdef __linux__
 303         dontkillme();
 304 #endif
 305
 306         if (!getpwuid(getuid()))
 307                 die("no passwd entry for you\n");
 308
 309 #ifndef HAVE_BSD_AUTH
 310         pws = getpw();
 311 #endif
 312
 313         if (!(dpy = XOpenDisplay(0)))
 314                 die("cannot open display\n");
 315         rr = XRRQueryExtension(dpy, &rrevbase, &rrerrbase);
 316         /* Get the number of screens in display "dpy" and blank them all. */
 317         nscreens = ScreenCount(dpy);
 318         if (!(locks = malloc(sizeof(Lock*) * nscreens)))
 319                 die("Out of memory.\n");
 320         int nlocks = 0;
 321         for (screen = 0; screen < nscreens; screen++) {
 322                 if ((locks[screen] = lockscreen(dpy, screen)) != NULL)
 323                         nlocks++;
 324         }
 325         XSync(dpy, False);
 326
 327         /* Did we actually manage to lock something? */
 328         if (nlocks == 0) { /* nothing to protect */
 329                 free(locks);
 330                 XCloseDisplay(dpy);
 331                 return 1;
 332         }
 333
 334         if (argc >= 2 && fork() == 0) {
 335                 if (dpy)
 336                         close(ConnectionNumber(dpy));
 337                 execvp(argv[1], argv+1);
 338                 die("execvp %s failed: %s\n", argv[1], strerror(errno));
 339         }
 340
 341         /* Everything is now blank. Now wait for the correct password. */
 342 #ifdef HAVE_BSD_AUTH
 343         readpw(dpy);
 344 #else
 345         readpw(dpy, pws);
 346 #endif
 347
 348         /* Password ok, unlock everything and quit. */
 349         for (screen = 0; screen < nscreens; screen++)
 350                 unlockscreen(dpy, locks[screen]);
 351
 352         free(locks);
 353         XCloseDisplay(dpy);
 354
 355         return 0;
 356 }