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