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 #include "arg.h"
  22 #include "util.h"
  23
  24 char *argv0;
  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 rr;
  45 static int rrevbase;
  46 static int rrerrbase;
  47
  48 static void
  49 die(const char *errstr, ...)
  50 {
  51         va_list ap;
  52
  53         va_start(ap, errstr);
  54         vfprintf(stderr, errstr, ap);
  55         va_end(ap);
  56         exit(1);
  57 }
  58
  59 #ifdef __linux__
  60 #include <fcntl.h>
  61 #include <linux/oom.h>
  62
  63 static void
  64 dontkillme(void)
  65 {
  66         FILE *f;
  67         const char oomfile[] = "/proc/self/oom_score_adj";
  68
  69         if (!(f = fopen(oomfile, "w"))) {
  70                 if (errno == ENOENT)
  71                         return;
  72                 die("slock: fopen %s: %s\n", oomfile, strerror(errno));
  73         }
  74         fprintf(f, "%d", OOM_SCORE_ADJ_MIN);
  75         if (fclose(f)) {
  76                 if (errno == EACCES)
  77                         die("slock: unable to disable OOM killer. "
  78                             "suid or sgid set?\n");
  79                 else
  80                         die("slock: fclose %s: %s\n", oomfile,
  81                             strerror(errno));
  82         }
  83 }
  84 #endif
  85
  86 /* only run as root */
  87 static const char *
  88 getpw(void)
  89 {
  90         const char *rval;
  91         struct passwd *pw;
  92
  93         /* Check if the current user has a password entry */
  94         errno = 0;
  95         if (!(pw = getpwuid(getuid()))) {
  96                 if (errno)
  97                         die("slock: getpwuid: %s\n", strerror(errno));
  98                 else
  99                         die("slock: cannot retrieve password entry\n");
 100         }
 101         rval = pw->pw_passwd;
 102
 103 #if HAVE_SHADOW_H
 104         if (rval[0] == 'x' && rval[1] == '\0') {
 105                 struct spwd *sp;
 106                 if (!(sp = getspnam(getenv("USER"))))
 107                         die("slock: getspnam: cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
 108                 rval = sp->sp_pwdp;
 109         }
 110 #else
 111         if (rval[0] == '*' && rval[1] == '\0') {
 112 #ifdef __OpenBSD__
 113                 if (!(pw = getpwnam_shadow(getenv("USER"))))
 114                         die("slock: getpwnam_shadow: cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
 115                 rval = pw->pw_passwd;
 116 #else
 117                 die("slock: getpwuid: cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
 118 #endif /* __OpenBSD__ */
 119         }
 120 #endif /* HAVE_SHADOW_H */
 121
 122         /* drop privileges */
 123         if (geteuid() == 0 &&
 124             ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
 125                 die("slock: cannot drop privileges\n");
 126         return rval;
 127 }
 128
 129 static void
 130 readpw(Display *dpy, const char *pws)
 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                                 errno = 0;
 167                                 if (!(encrypted = crypt(passwd, pws)))
 168                                         fprintf(stderr, "slock: crypt: %s\n", strerror(errno));
 169                                 else
 170                                         running = !!strcmp(encrypted, pws);
 171                                 if (running) {
 172                                         XBell(dpy, 100);
 173                                         failure = True;
 174                                 }
 175                                 explicit_bzero(&passwd, sizeof(passwd));
 176                                 len = 0;
 177                                 break;
 178                         case XK_Escape:
 179                                 explicit_bzero(&passwd, sizeof(passwd));
 180                                 len = 0;
 181                                 break;
 182                         case XK_BackSpace:
 183                                 if (len)
 184                                         passwd[len--] = 0;
 185                                 break;
 186                         default:
 187                                 if (num && !iscntrl((int)buf[0]) && (len + num < sizeof(passwd))) {
 188                                         memcpy(passwd + len, buf, num);
 189                                         len += num;
 190                                 }
 191                                 break;
 192                         }
 193                         color = len ? INPUT : (failure || failonclear ? FAILED : INIT);
 194                         if (running && oldc != color) {
 195                                 for (screen = 0; screen < nscreens; screen++) {
 196                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[color]);
 197                                         XClearWindow(dpy, locks[screen]->win);
 198                                 }
 199                                 oldc = color;
 200                         }
 201                 } else if (rr && ev.type == rrevbase + RRScreenChangeNotify) {
 202                         XRRScreenChangeNotifyEvent *rre = (XRRScreenChangeNotifyEvent*)&ev;
 203                         for (screen = 0; screen < nscreens; screen++) {
 204                                 if (locks[screen]->win == rre->window) {
 205                                         XResizeWindow(dpy, locks[screen]->win, rre->width, rre->height);
 206                                         XClearWindow(dpy, locks[screen]->win);
 207                                 }
 208                         }
 209                 } else for (screen = 0; screen < nscreens; screen++)
 210                         XRaiseWindow(dpy, locks[screen]->win);
 211         }
 212 }
 213
 214 static void
 215 unlockscreen(Display *dpy, Lock *lock)
 216 {
 217         if(dpy == NULL || lock == NULL)
 218                 return;
 219
 220         XUngrabPointer(dpy, CurrentTime);
 221         XUngrabKeyboard(dpy, CurrentTime);
 222         XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, NUMCOLS, 0);
 223         XFreePixmap(dpy, lock->pmap);
 224         XDestroyWindow(dpy, lock->win);
 225
 226         free(lock);
 227 }
 228
 229 static void
 230 cleanup(Display *dpy)
 231 {
 232         int s;
 233
 234         for (s = 0; s < nscreens; ++s)
 235                 unlockscreen(dpy, locks[s]);
 236
 237         free(locks);
 238         XCloseDisplay(dpy);
 239 }
 240
 241 static Lock *
 242 lockscreen(Display *dpy, int screen)
 243 {
 244         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
 245         int i, ptgrab, kbgrab;
 246         Lock *lock;
 247         XColor color, dummy;
 248         XSetWindowAttributes wa;
 249         Cursor invisible;
 250
 251         if (dpy == NULL || screen < 0 || !(lock = malloc(sizeof(Lock))))
 252                 return NULL;
 253
 254         lock->screen = screen;
 255         lock->root = RootWindow(dpy, lock->screen);
 256
 257         for (i = 0; i < NUMCOLS; i++) {
 258                 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), colorname[i], &color, &dummy);
 259                 lock->colors[i] = color.pixel;
 260         }
 261
 262         /* init */
 263         wa.override_redirect = 1;
 264         wa.background_pixel = lock->colors[INIT];
 265         lock->win = XCreateWindow(dpy, lock->root, 0, 0, DisplayWidth(dpy, lock->screen), DisplayHeight(dpy, lock->screen),
 266                                   0, DefaultDepth(dpy, lock->screen), CopyFromParent,
 267                                   DefaultVisual(dpy, lock->screen), CWOverrideRedirect | CWBackPixel, &wa);
 268         lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
 269         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
 270         XDefineCursor(dpy, lock->win, invisible);
 271
 272         /* Try to grab mouse pointer *and* keyboard for 600ms, else fail the lock */
 273         for (i = 0, ptgrab = kbgrab = -1; i < 6; i++) {
 274                 if (ptgrab != GrabSuccess) {
 275                         ptgrab = XGrabPointer(dpy, lock->root, False,
 276                                  ButtonPressMask | ButtonReleaseMask |
 277                                  PointerMotionMask, GrabModeAsync,
 278                                  GrabModeAsync, None, invisible, CurrentTime);
 279                 }
 280                 if (kbgrab != GrabSuccess) {
 281                         kbgrab = XGrabKeyboard(dpy, lock->root, True,
 282                                  GrabModeAsync, GrabModeAsync, CurrentTime);
 283                 }
 284
 285                 /* input is grabbed: we can lock the screen */
 286                 if (ptgrab == GrabSuccess && kbgrab == GrabSuccess) {
 287                         XMapRaised(dpy, lock->win);
 288                         if (rr)
 289                                 XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
 290
 291                         XSelectInput(dpy, lock->root, SubstructureNotifyMask);
 292                         return lock;
 293                 }
 294
 295                 /* retry on AlreadyGrabbed but fail on other errors */
 296                 if ((ptgrab != AlreadyGrabbed && ptgrab != GrabSuccess) ||
 297                     (kbgrab != AlreadyGrabbed && kbgrab != GrabSuccess))
 298                         break;
 299
 300                 usleep(100000);
 301         }
 302
 303         /* we couldn't grab all input: fail out */
 304         if (ptgrab != GrabSuccess)
 305                 fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n", screen);
 306         if (kbgrab != GrabSuccess)
 307                 fprintf(stderr, "slock: unable to grab keyboard for screen %d\n", screen);
 308         return NULL;
 309 }
 310
 311 static void
 312 usage(void)
 313 {
 314         die("usage: slock [-v] [cmd [arg ...]]\n");
 315 }
 316
 317 int
 318 main(int argc, char **argv) {
 319         const char *pws;
 320         Display *dpy;
 321         int s, nlocks;
 322
 323         ARGBEGIN {
 324         case 'v':
 325                 fprintf(stderr, "slock-"VERSION"\n");
 326                 return 0;
 327         default:
 328                 usage();
 329         } ARGEND
 330
 331 #ifdef __linux__
 332         dontkillme();
 333 #endif
 334
 335         pws = getpw();
 336         if (strlen(pws) < 2)
 337                 die("slock: failed to get user password hash.\n");
 338
 339         if (!(dpy = XOpenDisplay(NULL)))
 340                 die("slock: cannot open display\n");
 341
 342         /* check for Xrandr support */
 343         rr = XRRQueryExtension(dpy, &rrevbase, &rrerrbase);
 344
 345         /* get number of screens in display "dpy" and blank them */
 346         nscreens = ScreenCount(dpy);
 347         if (!(locks = calloc(nscreens, sizeof(Lock *)))) {
 348                 XCloseDisplay(dpy);
 349                 die("slock: out of memory\n");
 350         }
 351         for (nlocks = 0, s = 0; s < nscreens; s++) {
 352                 if ((locks[s] = lockscreen(dpy, s)) != NULL)
 353                         nlocks++;
 354                 else
 355                         break;
 356         }
 357         XSync(dpy, 0);
 358
 359         /* did we manage to lock everything? */
 360         if (nlocks != nscreens) {
 361                 cleanup(dpy);
 362                 return 1;
 363         }
 364
 365         /* run post-lock command */
 366         if (argc > 0) {
 367                 switch (fork()) {
 368                 case -1:
 369                         cleanup(dpy);
 370                         die("slock: fork failed: %s\n", strerror(errno));
 371                 case 0:
 372                         if (close(ConnectionNumber(dpy)) < 0)
 373                                 die("slock: close: %s\n", strerror(errno));
 374                         execvp(argv[0], argv);
 375                         fprintf(stderr, "slock: execvp %s: %s\n", argv[0],
 376                                 strerror(errno));
 377                         _exit(1);
 378                 }
 379         }
 380
 381         /* everything is now blank. Wait for the correct password */
 382         readpw(dpy, pws);
 383
 384         /* password ok, unlock everything and quit */
 385         cleanup(dpy);
 386
 387         return 0;
 388 }