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 "arg.h"
  27 #include "util.h"
  28
  29 char *argv0;
  30
  31 enum {
  32         INIT,
  33         INPUT,
  34         FAILED,
  35         NUMCOLS
  36 };
  37
  38 #include "config.h"
  39
  40 typedef struct {
  41         int screen;
  42         Window root, win;
  43         Pixmap pmap;
  44         unsigned long colors[NUMCOLS];
  45 } Lock;
  46
  47 static Lock **locks;
  48 static int nscreens;
  49 static Bool running = True;
  50 static Bool failure = False;
  51 static Bool rr;
  52 static int rrevbase;
  53 static int rrerrbase;
  54
  55 static void
  56 die(const char *errstr, ...)
  57 {
  58         va_list ap;
  59
  60         va_start(ap, errstr);
  61         vfprintf(stderr, errstr, ap);
  62         va_end(ap);
  63         exit(1);
  64 }
  65
  66 #ifdef __linux__
  67 #include <fcntl.h>
  68
  69 static void
  70 dontkillme(void)
  71 {
  72         int fd;
  73
  74         fd = open("/proc/self/oom_score_adj", O_WRONLY);
  75         if (fd < 0 && errno == ENOENT) {
  76                 return;
  77         }
  78         if (fd < 0 || write(fd, "-1000\n", (sizeof("-1000\n") - 1)) !=
  79             (sizeof("-1000\n") - 1) || close(fd) != 0) {
  80                 die("can't tame the oom-killer. is suid or sgid set?\n");
  81         }
  82 }
  83 #endif
  84
  85 #ifndef HAVE_BSD_AUTH
  86 /* only run as root */
  87 static const char *
  88 getpw(void)
  89 {
  90         const char *rval;
  91         struct passwd *pw;
  92
  93         errno = 0;
  94         if (!(pw = getpwuid(getuid()))) {
  95                 if (errno)
  96                         die("getpwuid: %s\n", strerror(errno));
  97                 else
  98                         die("cannot retrieve password entry\n");
  99         }
 100         rval = pw->pw_passwd;
 101
 102 #if HAVE_SHADOW_H
 103         if (rval[0] == 'x' && rval[1] == '\0') {
 104                 struct spwd *sp;
 105                 if (!(sp = getspnam(getenv("USER"))))
 106                         die("cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
 107                 rval = sp->sp_pwdp;
 108         }
 109 #endif
 110
 111         /* drop privileges */
 112         if (geteuid() == 0 &&
 113             ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
 114                 die("cannot drop privileges\n");
 115         return rval;
 116 }
 117 #endif
 118
 119 static void
 120 #ifdef HAVE_BSD_AUTH
 121 readpw(Display *dpy)
 122 #else
 123 readpw(Display *dpy, const char *pws)
 124 #endif
 125 {
 126         char buf[32], passwd[256];
 127         int num, screen;
 128         unsigned int len, color;
 129         KeySym ksym;
 130         XEvent ev;
 131         static int oldc = INIT;
 132
 133         len = 0;
 134         running = True;
 135
 136         /* As "slock" stands for "Simple X display locker", the DPMS settings
 137          * had been removed and you can set it with "xset" or some other
 138          * utility. This way the user can easily set a customized DPMS
 139          * timeout. */
 140         while (running && !XNextEvent(dpy, &ev)) {
 141                 if (ev.type == KeyPress) {
 142                         explicit_bzero(&buf, sizeof(buf));
 143                         num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0);
 144                         if (IsKeypadKey(ksym)) {
 145                                 if (ksym == XK_KP_Enter)
 146                                         ksym = XK_Return;
 147                                 else if (ksym >= XK_KP_0 && ksym <= XK_KP_9)
 148                                         ksym = (ksym - XK_KP_0) + XK_0;
 149                         }
 150                         if (IsFunctionKey(ksym) ||
 151                             IsKeypadKey(ksym) ||
 152                             IsMiscFunctionKey(ksym) ||
 153                             IsPFKey(ksym) ||
 154                             IsPrivateKeypadKey(ksym))
 155                                 continue;
 156                         switch (ksym) {
 157                         case XK_Return:
 158                                 passwd[len] = 0;
 159 #ifdef HAVE_BSD_AUTH
 160                                 running = !auth_userokay(getlogin(), NULL, "auth-xlock", passwd);
 161 #else
 162                                 running = !!strcmp(crypt(passwd, pws), pws);
 163 #endif
 164                                 if (running) {
 165                                         XBell(dpy, 100);
 166                                         failure = True;
 167                                 }
 168                                 explicit_bzero(&passwd, sizeof(passwd));
 169                                 len = 0;
 170                                 break;
 171                         case XK_Escape:
 172                                 explicit_bzero(&passwd, sizeof(passwd));
 173                                 len = 0;
 174                                 break;
 175                         case XK_BackSpace:
 176                                 if (len)
 177                                         passwd[len--] = 0;
 178                                 break;
 179                         default:
 180                                 if (num && !iscntrl((int)buf[0]) && (len + num < sizeof(passwd))) {
 181                                         memcpy(passwd + len, buf, num);
 182                                         len += num;
 183                                 }
 184                                 break;
 185                         }
 186                         color = len ? INPUT : (failure || failonclear ? FAILED : INIT);
 187                         if (running && oldc != color) {
 188                                 for (screen = 0; screen < nscreens; screen++) {
 189                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[color]);
 190                                         XClearWindow(dpy, locks[screen]->win);
 191                                 }
 192                                 oldc = color;
 193                         }
 194                 } else if (rr && ev.type == rrevbase + RRScreenChangeNotify) {
 195                         XRRScreenChangeNotifyEvent *rre = (XRRScreenChangeNotifyEvent*)&ev;
 196                         for (screen = 0; screen < nscreens; screen++) {
 197                                 if (locks[screen]->win == rre->window) {
 198                                         XResizeWindow(dpy, locks[screen]->win, rre->width, rre->height);
 199                                         XClearWindow(dpy, locks[screen]->win);
 200                                 }
 201                         }
 202                 } else for (screen = 0; screen < nscreens; screen++)
 203                         XRaiseWindow(dpy, locks[screen]->win);
 204         }
 205 }
 206
 207 static void
 208 unlockscreen(Display *dpy, Lock *lock)
 209 {
 210         if(dpy == NULL || lock == NULL)
 211                 return;
 212
 213         XUngrabPointer(dpy, CurrentTime);
 214         XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, NUMCOLS, 0);
 215         XFreePixmap(dpy, lock->pmap);
 216         XDestroyWindow(dpy, lock->win);
 217
 218         free(lock);
 219 }
 220
 221 static Lock *
 222 lockscreen(Display *dpy, int screen)
 223 {
 224         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
 225         int i;
 226         Lock *lock;
 227         XColor color, dummy;
 228         XSetWindowAttributes wa;
 229         Cursor invisible;
 230
 231         if (!running || dpy == NULL || screen < 0 || !(lock = malloc(sizeof(Lock))))
 232                 return NULL;
 233
 234         lock->screen = screen;
 235         lock->root = RootWindow(dpy, lock->screen);
 236
 237         for (i = 0; i < NUMCOLS; i++) {
 238                 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), colorname[i], &color, &dummy);
 239                 lock->colors[i] = color.pixel;
 240         }
 241
 242         /* init */
 243         wa.override_redirect = 1;
 244         wa.background_pixel = lock->colors[INIT];
 245         lock->win = XCreateWindow(dpy, lock->root, 0, 0, DisplayWidth(dpy, lock->screen), DisplayHeight(dpy, lock->screen),
 246                                   0, DefaultDepth(dpy, lock->screen), CopyFromParent,
 247                                   DefaultVisual(dpy, lock->screen), CWOverrideRedirect | CWBackPixel, &wa);
 248         lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
 249         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
 250         XDefineCursor(dpy, lock->win, invisible);
 251
 252         /* Try to grab mouse pointer *and* keyboard, else fail the lock */
 253         if (XGrabPointer(dpy, lock->root, False, ButtonPressMask |
 254             ButtonReleaseMask | PointerMotionMask, GrabModeAsync, GrabModeAsync,
 255             None, invisible, CurrentTime) != GrabSuccess) {
 256                 fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n", screen);
 257                 running = 0;
 258                 unlockscreen(dpy, lock);
 259                 return NULL;
 260         }
 261
 262         if (XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync,
 263             CurrentTime) != GrabSuccess) {
 264                 fprintf(stderr, "slock: unable to grab keyboard for screen %d\n", screen);
 265                 running = 0;
 266                 unlockscreen(dpy, lock);
 267                 return NULL;
 268         }
 269
 270         XMapRaised(dpy, lock->win);
 271         if (rr)
 272                 XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
 273
 274         XSelectInput(dpy, lock->root, SubstructureNotifyMask);
 275         return lock;
 276 }
 277
 278 static void
 279 usage(void)
 280 {
 281         die("usage: slock [-v | cmd [arg ...]]\n");
 282 }
 283
 284 int
 285 main(int argc, char **argv) {
 286 #ifndef HAVE_BSD_AUTH
 287         const char *pws;
 288 #endif
 289         Display *dpy;
 290         int s, nlocks;
 291
 292         ARGBEGIN {
 293         case 'v':
 294                 fprintf(stderr, "slock-"VERSION"\n");
 295                 return 0;
 296         default:
 297                 usage();
 298         } ARGEND
 299
 300 #ifdef __linux__
 301         dontkillme();
 302 #endif
 303
 304         /* Check if the current user has a password entry */
 305         errno = 0;
 306         if (!getpwuid(getuid())) {
 307                 if (errno == 0)
 308                         die("slock: no password entry for current user\n");
 309                 else
 310                         die("slock: getpwuid: %s\n", strerror(errno));
 311         }
 312
 313 #ifndef HAVE_BSD_AUTH
 314         pws = getpw();
 315 #endif
 316
 317         if (!(dpy = XOpenDisplay(NULL)))
 318                 die("slock: cannot open display\n");
 319
 320         /* check for Xrandr support */
 321         rr = XRRQueryExtension(dpy, &rrevbase, &rrerrbase);
 322
 323         /* get number of screens in display "dpy" and blank them */
 324         nscreens = ScreenCount(dpy);
 325         if (!(locks = malloc(sizeof(Lock *) * nscreens))) {
 326                 XCloseDisplay(dpy);
 327                 die("slock: out of memory\n");
 328         }
 329         for (nlocks = 0, s = 0; s < nscreens; s++) {
 330                 if ((locks[s] = lockscreen(dpy, s)) != NULL)
 331                         nlocks++;
 332         }
 333         XSync(dpy, 0);
 334
 335         /* did we actually manage to lock anything? */
 336         if (nlocks == 0) {
 337                 /* nothing to protect */
 338                 free(locks);
 339                 XCloseDisplay(dpy);
 340                 return 1;
 341         }
 342
 343         /* run post-lock command */
 344         if (argc > 0) {
 345                 switch (fork()) {
 346                 case -1:
 347                         free(locks);
 348                         XCloseDisplay(dpy);
 349                         die("slock: fork failed: %s\n", strerror(errno));
 350                 case 0:
 351                         if (close(ConnectionNumber(dpy)) < 0)
 352                                 die("slock: close: %s\n", strerror(errno));
 353                         execvp(argv[0], argv);
 354                         fprintf(stderr, "slock: execvp %s: %s\n", argv[0],
 355                                 strerror(errno));
 356                         _exit(1);
 357                 }
 358         }
 359
 360         /* everything is now blank. Wait for the correct password */
 361 #ifdef HAVE_BSD_AUTH
 362         readpw(dpy);
 363 #else
 364         readpw(dpy, pws);
 365 #endif
 366
 367         /* password ok, unlock everything and quit */
 368         for (s = 0; s < nscreens; s++)
 369                 unlockscreen(dpy, locks[s]);
 370
 371         free(locks);
 372         XCloseDisplay(dpy);
 373
 374         return 0;
 375 }