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