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 rr;
  50 static int rrevbase;
  51 static int rrerrbase;
  52
  53 static void
  54 die(const char *errstr, ...)
  55 {
  56         va_list ap;
  57
  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 #include <linux/oom.h>
  67
  68 static void
  69 dontkillme(void)
  70 {
  71         FILE *f;
  72         const char oomfile[] = "/proc/self/oom_score_adj";
  73
  74         if (!(f = fopen(oomfile, "w"))) {
  75                 if (errno == ENOENT)
  76                         return;
  77                 die("slock: fopen %s: %s\n", oomfile, strerror(errno));
  78         }
  79         fprintf(f, "%d", OOM_SCORE_ADJ_MIN);
  80         if (fclose(f)) {
  81                 if (errno == EACCES)
  82                         die("slock: unable to disable OOM killer. "
  83                             "suid or sgid set?\n");
  84                 else
  85                         die("slock: fclose %s: %s\n", oomfile,
  86                             strerror(errno));
  87         }
  88 }
  89 #endif
  90
  91 #ifndef HAVE_BSD_AUTH
  92 /* only run as root */
  93 static const char *
  94 getpw(void)
  95 {
  96         const char *rval;
  97         struct passwd *pw;
  98
  99         errno = 0;
 100         if (!(pw = getpwuid(getuid()))) {
 101                 if (errno)
 102                         die("getpwuid: %s\n", strerror(errno));
 103                 else
 104                         die("cannot retrieve password entry\n");
 105         }
 106         rval = pw->pw_passwd;
 107
 108 #if HAVE_SHADOW_H
 109         if (rval[0] == 'x' && rval[1] == '\0') {
 110                 struct spwd *sp;
 111                 if (!(sp = getspnam(getenv("USER"))))
 112                         die("cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
 113                 rval = sp->sp_pwdp;
 114         }
 115 #endif
 116
 117         /* drop privileges */
 118         if (geteuid() == 0 &&
 119             ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
 120                 die("cannot drop privileges\n");
 121         return rval;
 122 }
 123 #endif
 124
 125 static void
 126 #ifdef HAVE_BSD_AUTH
 127 readpw(Display *dpy)
 128 #else
 129 readpw(Display *dpy, const char *pws)
 130 #endif
 131 {
 132         char buf[32], passwd[256], *encrypted;
 133         int num, screen, running, failure;
 134         unsigned int len, color;
 135         KeySym ksym;
 136         XEvent ev;
 137         static int oldc = INIT;
 138
 139         len = 0;
 140         running = 1;
 141         failure = 0;
 142
 143         /* As "slock" stands for "Simple X display locker", the DPMS settings
 144          * had been removed and you can set it with "xset" or some other
 145          * utility. This way the user can easily set a customized DPMS
 146          * timeout. */
 147         while (running && !XNextEvent(dpy, &ev)) {
 148                 if (ev.type == KeyPress) {
 149                         explicit_bzero(&buf, sizeof(buf));
 150                         num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0);
 151                         if (IsKeypadKey(ksym)) {
 152                                 if (ksym == XK_KP_Enter)
 153                                         ksym = XK_Return;
 154                                 else if (ksym >= XK_KP_0 && ksym <= XK_KP_9)
 155                                         ksym = (ksym - XK_KP_0) + XK_0;
 156                         }
 157                         if (IsFunctionKey(ksym) ||
 158                             IsKeypadKey(ksym) ||
 159                             IsMiscFunctionKey(ksym) ||
 160                             IsPFKey(ksym) ||
 161                             IsPrivateKeypadKey(ksym))
 162                                 continue;
 163                         switch (ksym) {
 164                         case XK_Return:
 165                                 passwd[len] = 0;
 166 #ifdef HAVE_BSD_AUTH
 167                                 running = !auth_userokay(getlogin(), NULL, "auth-slock", passwd);
 168 #else
 169                                 errno = 0;
 170                                 if (!(encrypted = crypt(passwd, pws)))
 171                                         fprintf(stderr, "slock: crypt: %s\n", strerror(errno));
 172                                 else
 173                                         running = !!strcmp(encrypted, pws);
 174 #endif
 175                                 if (running) {
 176                                         XBell(dpy, 100);
 177                                         failure = True;
 178                                 }
 179                                 explicit_bzero(&passwd, sizeof(passwd));
 180                                 len = 0;
 181                                 break;
 182                         case XK_Escape:
 183                                 explicit_bzero(&passwd, sizeof(passwd));
 184                                 len = 0;
 185                                 break;
 186                         case XK_BackSpace:
 187                                 if (len)
 188                                         passwd[len--] = 0;
 189                                 break;
 190                         default:
 191                                 if (num && !iscntrl((int)buf[0]) && (len + num < sizeof(passwd))) {
 192                                         memcpy(passwd + len, buf, num);
 193                                         len += num;
 194                                 }
 195                                 break;
 196                         }
 197                         color = len ? INPUT : (failure || failonclear ? FAILED : INIT);
 198                         if (running && oldc != color) {
 199                                 for (screen = 0; screen < nscreens; screen++) {
 200                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[color]);
 201                                         XClearWindow(dpy, locks[screen]->win);
 202                                 }
 203                                 oldc = color;
 204                         }
 205                 } else if (rr && ev.type == rrevbase + RRScreenChangeNotify) {
 206                         XRRScreenChangeNotifyEvent *rre = (XRRScreenChangeNotifyEvent*)&ev;
 207                         for (screen = 0; screen < nscreens; screen++) {
 208                                 if (locks[screen]->win == rre->window) {
 209                                         XResizeWindow(dpy, locks[screen]->win, rre->width, rre->height);
 210                                         XClearWindow(dpy, locks[screen]->win);
 211                                 }
 212                         }
 213                 } else for (screen = 0; screen < nscreens; screen++)
 214                         XRaiseWindow(dpy, locks[screen]->win);
 215         }
 216 }
 217
 218 static void
 219 unlockscreen(Display *dpy, Lock *lock)
 220 {
 221         if(dpy == NULL || lock == NULL)
 222                 return;
 223
 224         XUngrabPointer(dpy, CurrentTime);
 225         XUngrabKeyboard(dpy, CurrentTime);
 226         XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, NUMCOLS, 0);
 227         XFreePixmap(dpy, lock->pmap);
 228         XDestroyWindow(dpy, lock->win);
 229
 230         free(lock);
 231 }
 232
 233 static void
 234 cleanup(Display *dpy)
 235 {
 236         int s;
 237
 238         for (s = 0; s < nscreens; ++s)
 239                 unlockscreen(dpy, locks[s]);
 240
 241         free(locks);
 242         XCloseDisplay(dpy);
 243 }
 244
 245 static Lock *
 246 lockscreen(Display *dpy, int screen)
 247 {
 248         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
 249         int i, ptgrab, kbgrab;
 250         Lock *lock;
 251         XColor color, dummy;
 252         XSetWindowAttributes wa;
 253         Cursor invisible;
 254
 255         if (dpy == NULL || screen < 0 || !(lock = malloc(sizeof(Lock))))
 256                 return NULL;
 257
 258         lock->screen = screen;
 259         lock->root = RootWindow(dpy, lock->screen);
 260
 261         for (i = 0; i < NUMCOLS; i++) {
 262                 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), colorname[i], &color, &dummy);
 263                 lock->colors[i] = color.pixel;
 264         }
 265
 266         /* init */
 267         wa.override_redirect = 1;
 268         wa.background_pixel = lock->colors[INIT];
 269         lock->win = XCreateWindow(dpy, lock->root, 0, 0, DisplayWidth(dpy, lock->screen), DisplayHeight(dpy, lock->screen),
 270                                   0, DefaultDepth(dpy, lock->screen), CopyFromParent,
 271                                   DefaultVisual(dpy, lock->screen), CWOverrideRedirect | CWBackPixel, &wa);
 272         lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
 273         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
 274         XDefineCursor(dpy, lock->win, invisible);
 275
 276         /* Try to grab mouse pointer *and* keyboard for 600ms, else fail the lock */
 277         for (i = 6, ptgrab = kbgrab = -1; i; --i) {
 278                 if (ptgrab != GrabSuccess) {
 279                         ptgrab = XGrabPointer(dpy, lock->root, False,
 280                                  ButtonPressMask | ButtonReleaseMask |
 281                                  PointerMotionMask, GrabModeAsync,
 282                                  GrabModeAsync, None, invisible, CurrentTime);
 283                 }
 284                 if (kbgrab != GrabSuccess) {
 285                         kbgrab = XGrabKeyboard(dpy, lock->root, True,
 286                                  GrabModeAsync, GrabModeAsync, CurrentTime);
 287                 }
 288
 289                 /* input is grabbed: we can lock the screen */
 290                 if (ptgrab == GrabSuccess && kbgrab == GrabSuccess) {
 291                         XMapRaised(dpy, lock->win);
 292                         if (rr)
 293                                 XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
 294
 295                         XSelectInput(dpy, lock->root, SubstructureNotifyMask);
 296                         return lock;
 297                 }
 298
 299                 /* retry on AlreadyGrabbed but fail on other errors */
 300                 if ((ptgrab != AlreadyGrabbed && ptgrab != GrabSuccess) ||
 301                     (kbgrab != AlreadyGrabbed && kbgrab != GrabSuccess))
 302                         break;
 303
 304                 usleep(100000);
 305         }
 306
 307         /* we couldn't grab all input: fail out */
 308         if (ptgrab != GrabSuccess)
 309                 fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n", screen);
 310         if (kbgrab != GrabSuccess)
 311                 fprintf(stderr, "slock: unable to grab keyboard for screen %d\n", screen);
 312         return NULL;
 313 }
 314
 315 static void
 316 usage(void)
 317 {
 318         die("usage: slock [-v] [cmd [arg ...]]\n");
 319 }
 320
 321 int
 322 main(int argc, char **argv) {
 323 #ifndef HAVE_BSD_AUTH
 324         const char *pws;
 325 #endif
 326         Display *dpy;
 327         int s, nlocks;
 328
 329         ARGBEGIN {
 330         case 'v':
 331                 fprintf(stderr, "slock-"VERSION"\n");
 332                 return 0;
 333         default:
 334                 usage();
 335         } ARGEND
 336
 337 #ifdef __linux__
 338         dontkillme();
 339 #endif
 340
 341         /* Check if the current user has a password entry */
 342         errno = 0;
 343         if (!getpwuid(getuid())) {
 344                 if (errno == 0)
 345                         die("slock: no password entry for current user\n");
 346                 else
 347                         die("slock: getpwuid: %s\n", strerror(errno));
 348         }
 349
 350 #ifndef HAVE_BSD_AUTH
 351         pws = getpw();
 352         if (strlen(pws) < 2)
 353                 die("slock: failed to get user password hash.\n");
 354 #endif
 355
 356         if (!(dpy = XOpenDisplay(NULL)))
 357                 die("slock: cannot open display\n");
 358
 359         /* check for Xrandr support */
 360         rr = XRRQueryExtension(dpy, &rrevbase, &rrerrbase);
 361
 362         /* get number of screens in display "dpy" and blank them */
 363         nscreens = ScreenCount(dpy);
 364         if (!(locks = calloc(nscreens, sizeof(Lock *)))) {
 365                 XCloseDisplay(dpy);
 366                 die("slock: out of memory\n");
 367         }
 368         for (nlocks = 0, s = 0; s < nscreens; s++) {
 369                 if ((locks[s] = lockscreen(dpy, s)) != NULL)
 370                         nlocks++;
 371                 else
 372                         break;
 373         }
 374         XSync(dpy, 0);
 375
 376         /* did we manage to lock everything? */
 377         if (nlocks != nscreens) {
 378                 cleanup(dpy);
 379                 return 1;
 380         }
 381
 382         /* run post-lock command */
 383         if (argc > 0) {
 384                 switch (fork()) {
 385                 case -1:
 386                         cleanup(dpy);
 387                         die("slock: fork failed: %s\n", strerror(errno));
 388                 case 0:
 389                         if (close(ConnectionNumber(dpy)) < 0)
 390                                 die("slock: close: %s\n", strerror(errno));
 391                         execvp(argv[0], argv);
 392                         fprintf(stderr, "slock: execvp %s: %s\n", argv[0],
 393                                 strerror(errno));
 394                         _exit(1);
 395                 }
 396         }
 397
 398         /* everything is now blank. Wait for the correct password */
 399 #ifdef HAVE_BSD_AUTH
 400         readpw(dpy);
 401 #else
 402         readpw(dpy, pws);
 403 #endif
 404
 405         /* password ok, unlock everything and quit */
 406         cleanup(dpy);
 407
 408         return 0;
 409 }