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