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 <math.h>
  10 #include <grp.h>
  11 #include <pwd.h>
  12 #include <stdarg.h>
  13 #include <stdlib.h>
  14 #include <stdio.h>
  15 #include <string.h>
  16 #include <unistd.h>
  17 #include <sys/types.h>
  18 #include <X11/extensions/Xrandr.h>
  19 #include <X11/keysym.h>
  20 #include <X11/Xlib.h>
  21 #include <X11/Xutil.h>
  22 #include <X11/Xresource.h>
  23
  24 #include "arg.h"
  25 #include "util.h"
  26
  27 char *argv0;
  28
  29 enum {
  30         INIT,
  31         INPUT,
  32         FAILED,
  33         NUMCOLS
  34 };
  35
  36 struct lock {
  37         int screen;
  38         Window root, win;
  39         Pixmap pmap;
  40         unsigned long colors[NUMCOLS];
  41 };
  42
  43 struct xrandr {
  44         int active;
  45         int evbase;
  46         int errbase;
  47 };
  48
  49 /* Xresources preferences */
  50 enum resource_type {
  51         STRING = 0,
  52         INTEGER = 1,
  53         FLOAT = 2
  54 };
  55
  56 typedef struct {
  57         char *name;
  58         enum resource_type type;
  59         void *dst;
  60 } ResourcePref;
  61
  62 #include "config.h"
  63
  64 static void
  65 die(const char *errstr, ...)
  66 {
  67         va_list ap;
  68
  69         va_start(ap, errstr);
  70         vfprintf(stderr, errstr, ap);
  71         va_end(ap);
  72         exit(1);
  73 }
  74
  75 #ifdef __linux__
  76 #include <fcntl.h>
  77 #include <linux/oom.h>
  78
  79 static void
  80 dontkillme(void)
  81 {
  82         FILE *f;
  83         const char oomfile[] = "/proc/self/oom_score_adj";
  84
  85         if (!(f = fopen(oomfile, "w"))) {
  86                 if (errno == ENOENT)
  87                         return;
  88                 die("slock: fopen %s: %s\n", oomfile, strerror(errno));
  89         }
  90         fprintf(f, "%d", OOM_SCORE_ADJ_MIN);
  91         if (fclose(f)) {
  92                 if (errno == EACCES)
  93                         die("slock: unable to disable OOM killer. "
  94                             "Make sure to suid or sgid slock.\n");
  95                 else
  96                         die("slock: fclose %s: %s\n", oomfile, strerror(errno));
  97         }
  98 }
  99 #endif
 100
 101 static const char *
 102 gethash(void)
 103 {
 104         const char *hash;
 105         struct passwd *pw;
 106
 107         /* Check if the current user has a password entry */
 108         errno = 0;
 109         if (!(pw = getpwuid(getuid()))) {
 110                 if (errno)
 111                         die("slock: getpwuid: %s\n", strerror(errno));
 112                 else
 113                         die("slock: cannot retrieve password entry\n");
 114         }
 115         hash = pw->pw_passwd;
 116
 117 #if HAVE_SHADOW_H
 118         if (!strcmp(hash, "x")) {
 119                 struct spwd *sp;
 120                 if (!(sp = getspnam(pw->pw_name)))
 121                         die("slock: getspnam: cannot retrieve shadow entry. "
 122                             "Make sure to suid or sgid slock.\n");
 123                 hash = sp->sp_pwdp;
 124         }
 125 #else
 126         if (!strcmp(hash, "*")) {
 127 #ifdef __OpenBSD__
 128                 if (!(pw = getpwuid_shadow(getuid())))
 129                         die("slock: getpwnam_shadow: cannot retrieve shadow entry. "
 130                             "Make sure to suid or sgid slock.\n");
 131                 hash = pw->pw_passwd;
 132 #else
 133                 die("slock: getpwuid: cannot retrieve shadow entry. "
 134                     "Make sure to suid or sgid slock.\n");
 135 #endif /* __OpenBSD__ */
 136         }
 137 #endif /* HAVE_SHADOW_H */
 138
 139         return hash;
 140 }
 141
 142 static void
 143 readpw(Display *dpy, struct xrandr *rr, struct lock **locks, int nscreens,
 144        const char *hash)
 145 {
 146         XRRScreenChangeNotifyEvent *rre;
 147         char buf[32], passwd[256], *inputhash;
 148         int num, screen, running, failure, oldc;
 149         unsigned int len, color;
 150         KeySym ksym;
 151         XEvent ev;
 152
 153         len = 0;
 154         running = 1;
 155         failure = 0;
 156         oldc = INIT;
 157
 158         while (running && !XNextEvent(dpy, &ev)) {
 159                 if (ev.type == KeyPress) {
 160                         explicit_bzero(&buf, sizeof(buf));
 161                         num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0);
 162                         if (IsKeypadKey(ksym)) {
 163                                 if (ksym == XK_KP_Enter)
 164                                         ksym = XK_Return;
 165                                 else if (ksym >= XK_KP_0 && ksym <= XK_KP_9)
 166                                         ksym = (ksym - XK_KP_0) + XK_0;
 167                         }
 168                         if (IsFunctionKey(ksym) ||
 169                             IsKeypadKey(ksym) ||
 170                             IsMiscFunctionKey(ksym) ||
 171                             IsPFKey(ksym) ||
 172                             IsPrivateKeypadKey(ksym))
 173                                 continue;
 174                         switch (ksym) {
 175                         case XK_Return:
 176                                 passwd[len] = '\0';
 177                                 errno = 0;
 178                                 if (!(inputhash = crypt(passwd, hash)))
 179                                         fprintf(stderr, "slock: crypt: %s\n", strerror(errno));
 180                                 else
 181                                         running = !!strcmp(inputhash, hash);
 182                                 if (running) {
 183                                         XBell(dpy, 100);
 184                                         failure = 1;
 185                                 }
 186                                 explicit_bzero(&passwd, sizeof(passwd));
 187                                 len = 0;
 188                                 break;
 189                         case XK_Escape:
 190                                 explicit_bzero(&passwd, sizeof(passwd));
 191                                 len = 0;
 192                                 break;
 193                         case XK_BackSpace:
 194                                 if (len)
 195                                         passwd[--len] = '\0';
 196                                 break;
 197                         default:
 198                                 if (num && !iscntrl((int)buf[0]) &&
 199                                     (len + num < sizeof(passwd))) {
 200                                         memcpy(passwd + len, buf, num);
 201                                         len += num;
 202                                 }
 203                                 break;
 204                         }
 205                         color = len ? INPUT : ((failure || failonclear) ? FAILED : INIT);
 206                         if (running && oldc != color) {
 207                                 for (screen = 0; screen < nscreens; screen++) {
 208                                         XSetWindowBackground(dpy,
 209                                                              locks[screen]->win,
 210                                                              locks[screen]->colors[color]);
 211                                         XClearWindow(dpy, locks[screen]->win);
 212                                 }
 213                                 oldc = color;
 214                         }
 215                 } else if (rr->active && ev.type == rr->evbase + RRScreenChangeNotify) {
 216                         rre = (XRRScreenChangeNotifyEvent*)&ev;
 217                         for (screen = 0; screen < nscreens; screen++) {
 218                                 if (locks[screen]->win == rre->window) {
 219                                         if (rre->rotation == RR_Rotate_90 ||
 220                                             rre->rotation == RR_Rotate_270)
 221                                                 XResizeWindow(dpy, locks[screen]->win,
 222                                                               rre->height, rre->width);
 223                                         else
 224                                                 XResizeWindow(dpy, locks[screen]->win,
 225                                                               rre->width, rre->height);
 226                                         XClearWindow(dpy, locks[screen]->win);
 227                                         break;
 228                                 }
 229                         }
 230                 } else {
 231                         for (screen = 0; screen < nscreens; screen++)
 232                                 XRaiseWindow(dpy, locks[screen]->win);
 233                 }
 234         }
 235 }
 236
 237 static struct lock *
 238 lockscreen(Display *dpy, struct xrandr *rr, int screen)
 239 {
 240         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
 241         int i, ptgrab, kbgrab;
 242         struct lock *lock;
 243         XColor color, dummy;
 244         XSetWindowAttributes wa;
 245         Cursor invisible;
 246
 247         if (dpy == NULL || screen < 0 || !(lock = malloc(sizeof(struct lock))))
 248                 return NULL;
 249
 250         lock->screen = screen;
 251         lock->root = RootWindow(dpy, lock->screen);
 252
 253         for (i = 0; i < NUMCOLS; i++) {
 254                 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen),
 255                                  colorname[i], &color, &dummy);
 256                 lock->colors[i] = color.pixel;
 257         }
 258
 259         /* init */
 260         wa.override_redirect = 1;
 261         wa.background_pixel = lock->colors[INIT];
 262         lock->win = XCreateWindow(dpy, lock->root, 0, 0,
 263                                   DisplayWidth(dpy, lock->screen),
 264                                   DisplayHeight(dpy, lock->screen),
 265                                   0, DefaultDepth(dpy, lock->screen),
 266                                   CopyFromParent,
 267                                   DefaultVisual(dpy, lock->screen),
 268                                   CWOverrideRedirect | CWBackPixel, &wa);
 269         lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
 270         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap,
 271                                         &color, &color, 0, 0);
 272         XDefineCursor(dpy, lock->win, invisible);
 273
 274         /* Try to grab mouse pointer *and* keyboard for 600ms, else fail the lock */
 275         for (i = 0, ptgrab = kbgrab = -1; i < 6; i++) {
 276                 if (ptgrab != GrabSuccess) {
 277                         ptgrab = XGrabPointer(dpy, lock->root, False,
 278                                               ButtonPressMask | ButtonReleaseMask |
 279                                               PointerMotionMask, GrabModeAsync,
 280                                               GrabModeAsync, None, invisible, CurrentTime);
 281                 }
 282                 if (kbgrab != GrabSuccess) {
 283                         kbgrab = XGrabKeyboard(dpy, lock->root, True,
 284                                                GrabModeAsync, GrabModeAsync, CurrentTime);
 285                 }
 286
 287                 /* input is grabbed: we can lock the screen */
 288                 if (ptgrab == GrabSuccess && kbgrab == GrabSuccess) {
 289                         XMapRaised(dpy, lock->win);
 290                         if (rr->active)
 291                                 XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
 292
 293                         XSelectInput(dpy, lock->root, SubstructureNotifyMask);
 294                         return lock;
 295                 }
 296
 297                 /* retry on AlreadyGrabbed but fail on other errors */
 298                 if ((ptgrab != AlreadyGrabbed && ptgrab != GrabSuccess) ||
 299                     (kbgrab != AlreadyGrabbed && kbgrab != GrabSuccess))
 300                         break;
 301
 302                 usleep(100000);
 303         }
 304
 305         /* we couldn't grab all input: fail out */
 306         if (ptgrab != GrabSuccess)
 307                 fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n",
 308                         screen);
 309         if (kbgrab != GrabSuccess)
 310                 fprintf(stderr, "slock: unable to grab keyboard for screen %d\n",
 311                         screen);
 312         return NULL;
 313 }
 314
 315 int
 316 resource_load(XrmDatabase db, char *name, enum resource_type rtype, void *dst)
 317 {
 318         char **sdst = dst;
 319         int *idst = dst;
 320         float *fdst = dst;
 321
 322         char fullname[256];
 323         char fullclass[256];
 324         char *type;
 325         XrmValue ret;
 326
 327         snprintf(fullname, sizeof(fullname), "%s.%s", "slock", name);
 328         snprintf(fullclass, sizeof(fullclass), "%s.%s", "Slock", name);
 329         fullname[sizeof(fullname) - 1] = fullclass[sizeof(fullclass) - 1] = '\0';
 330
 331         XrmGetResource(db, fullname, fullclass, &type, &ret);
 332         if (ret.addr == NULL || strncmp("String", type, 64))
 333                 return 1;
 334
 335         switch (rtype) {
 336         case STRING:
 337                 *sdst = ret.addr;
 338                 break;
 339         case INTEGER:
 340                 *idst = strtoul(ret.addr, NULL, 10);
 341                 break;
 342         case FLOAT:
 343                 *fdst = strtof(ret.addr, NULL);
 344                 break;
 345         }
 346         return 0;
 347 }
 348
 349 void
 350 config_init(Display *dpy)
 351 {
 352         char *resm;
 353         XrmDatabase db;
 354         ResourcePref *p;
 355
 356         XrmInitialize();
 357         resm = XResourceManagerString(dpy);
 358         if (!resm)
 359                 return;
 360
 361         db = XrmGetStringDatabase(resm);
 362         for (p = resources; p < resources + LEN(resources); p++)
 363                 resource_load(db, p->name, p->type, p->dst);
 364 }
 365
 366 static void
 367 usage(void)
 368 {
 369         die("usage: slock [-v] [cmd [arg ...]]\n");
 370 }
 371
 372 int
 373 main(int argc, char **argv) {
 374         struct xrandr rr;
 375         struct lock **locks;
 376         struct passwd *pwd;
 377         struct group *grp;
 378         uid_t duid;
 379         gid_t dgid;
 380         const char *hash;
 381         Display *dpy;
 382         int s, nlocks, nscreens;
 383
 384         ARGBEGIN {
 385         case 'v':
 386                 fprintf(stderr, "slock-"VERSION"\n");
 387                 return 0;
 388         default:
 389                 usage();
 390         } ARGEND
 391
 392         /* validate drop-user and -group */
 393         errno = 0;
 394         if (!(pwd = getpwnam(user)))
 395                 die("slock: getpwnam %s: %s\n", user,
 396                     errno ? strerror(errno) : "user entry not found");
 397         duid = pwd->pw_uid;
 398         errno = 0;
 399         if (!(grp = getgrnam(group)))
 400                 die("slock: getgrnam %s: %s\n", group,
 401                     errno ? strerror(errno) : "group entry not found");
 402         dgid = grp->gr_gid;
 403
 404 #ifdef __linux__
 405         dontkillme();
 406 #endif
 407
 408         hash = gethash();
 409         errno = 0;
 410         if (!crypt("", hash))
 411                 die("slock: crypt: %s\n", strerror(errno));
 412
 413         if (!(dpy = XOpenDisplay(NULL)))
 414                 die("slock: cannot open display\n");
 415
 416         /* drop privileges */
 417         if (setgroups(0, NULL) < 0)
 418                 die("slock: setgroups: %s\n", strerror(errno));
 419         if (setgid(dgid) < 0)
 420                 die("slock: setgid: %s\n", strerror(errno));
 421         if (setuid(duid) < 0)
 422                 die("slock: setuid: %s\n", strerror(errno));
 423
 424         config_init(dpy);
 425
 426         /* check for Xrandr support */
 427         rr.active = XRRQueryExtension(dpy, &rr.evbase, &rr.errbase);
 428
 429         /* get number of screens in display "dpy" and blank them */
 430         nscreens = ScreenCount(dpy);
 431         if (!(locks = calloc(nscreens, sizeof(struct lock *))))
 432                 die("slock: out of memory\n");
 433         for (nlocks = 0, s = 0; s < nscreens; s++) {
 434                 if ((locks[s] = lockscreen(dpy, &rr, s)) != NULL)
 435                         nlocks++;
 436                 else
 437                         break;
 438         }
 439         XSync(dpy, 0);
 440
 441         /* did we manage to lock everything? */
 442         if (nlocks != nscreens)
 443                 return 1;
 444
 445         /* run post-lock command */
 446         if (argc > 0) {
 447                 switch (fork()) {
 448                 case -1:
 449                         die("slock: fork failed: %s\n", strerror(errno));
 450                 case 0:
 451                         if (close(ConnectionNumber(dpy)) < 0)
 452                                 die("slock: close: %s\n", strerror(errno));
 453                         execvp(argv[0], argv);
 454                         fprintf(stderr, "slock: execvp %s: %s\n", argv[0], strerror(errno));
 455                         _exit(1);
 456                 }
 457         }
 458
 459         /* everything is now blank. Wait for the correct password */
 460         readpw(dpy, &rr, locks, nscreens, hash);
 461
 462         return 0;
 463 }