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 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 running = True;
  45 static Bool failure = False;
  46 static Bool rr;
  47 static int rrevbase;
  48 static int rrerrbase;
  49
  50 static void
  51 die(const char *errstr, ...)
  52 {
  53         va_list ap;
  54
  55         va_start(ap, errstr);
  56         vfprintf(stderr, errstr, ap);
  57         va_end(ap);
  58         exit(1);
  59 }
  60
  61 #ifdef __linux__
  62 #include <fcntl.h>
  63
  64 static void
  65 dontkillme(void)
  66 {
  67         int fd;
  68
  69         fd = open("/proc/self/oom_score_adj", O_WRONLY);
  70         if (fd < 0 && errno == ENOENT)
  71                 return;
  72         if (fd < 0 || write(fd, "-1000\n", 6) != 6 || close(fd) != 0)
  73                 die("cannot disable the out-of-memory killer for this process\n");
  74 }
  75 #endif
  76
  77 #ifndef HAVE_BSD_AUTH
  78 /* only run as root */
  79 static const char *
  80 getpw(void)
  81 {
  82         const char *rval;
  83         struct passwd *pw;
  84
  85         errno = 0;
  86         pw = getpwuid(getuid());
  87         if (!pw) {
  88                 if (errno)
  89                         die("slock: getpwuid: %s\n", strerror(errno));
  90                 else
  91                         die("slock: cannot retrieve password entry\n");
  92         }
  93         rval =  pw->pw_passwd;
  94
  95 #if HAVE_SHADOW_H
  96         if (rval[0] == 'x' && rval[1] == '\0') {
  97                 struct spwd *sp;
  98                 sp = getspnam(getenv("USER"));
  99                 if (!sp)
 100                         die("slock: cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
 101                 rval = sp->sp_pwdp;
 102         }
 103 #endif
 104
 105         /* drop privileges */
 106         if (geteuid() == 0 &&
 107             ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
 108                 die("slock: cannot drop privileges\n");
 109         return rval;
 110 }
 111 #endif
 112
 113 static void
 114 #ifdef HAVE_BSD_AUTH
 115 readpw(Display *dpy)
 116 #else
 117 readpw(Display *dpy, const char *pws)
 118 #endif
 119 {
 120         char buf[32], passwd[256];
 121         int num, screen;
 122         unsigned int len, llen;
 123         KeySym ksym;
 124         XEvent ev;
 125
 126         len = llen = 0;
 127         running = True;
 128
 129         /* As "slock" stands for "Simple X display locker", the DPMS settings
 130          * had been removed and you can set it with "xset" or some other
 131          * utility. This way the user can easily set a customized DPMS
 132          * timeout. */
 133         while (running && !XNextEvent(dpy, &ev)) {
 134                 if (ev.type == KeyPress) {
 135                         buf[0] = 0;
 136                         num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0);
 137                         if (IsKeypadKey(ksym)) {
 138                                 if (ksym == XK_KP_Enter)
 139                                         ksym = XK_Return;
 140                                 else if (ksym >= XK_KP_0 && ksym <= XK_KP_9)
 141                                         ksym = (ksym - XK_KP_0) + XK_0;
 142                         }
 143                         if (IsFunctionKey(ksym) ||
 144                             IsKeypadKey(ksym) ||
 145                             IsMiscFunctionKey(ksym) ||
 146                             IsPFKey(ksym) ||
 147                             IsPrivateKeypadKey(ksym))
 148                                 continue;
 149                         switch (ksym) {
 150                         case XK_Return:
 151                                 passwd[len] = 0;
 152 #ifdef HAVE_BSD_AUTH
 153                                 running = !auth_userokay(getlogin(), NULL, "auth-xlock", passwd);
 154 #else
 155                                 running = !!strcmp(crypt(passwd, pws), pws);
 156 #endif
 157                                 if (running) {
 158                                         XBell(dpy, 100);
 159                                         failure = True;
 160                                 }
 161                                 len = 0;
 162                                 break;
 163                         case XK_Escape:
 164                                 len = 0;
 165                                 break;
 166                         case XK_BackSpace:
 167                                 if (len)
 168                                         --len;
 169                                 break;
 170                         default:
 171                                 if (num && !iscntrl((int) buf[0]) && (len + num < sizeof(passwd))) {
 172                                         memcpy(passwd + len, buf, num);
 173                                         len += num;
 174                                 }
 175                                 break;
 176                         }
 177                         if (llen == 0 && len != 0) {
 178                                 for (screen = 0; screen < nscreens; screen++) {
 179                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[INPUT]);
 180                                         XClearWindow(dpy, locks[screen]->win);
 181                                 }
 182                         } else if (llen != 0 && len == 0) {
 183                                 for (screen = 0; screen < nscreens; screen++) {
 184                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[failure || failonclear ? FAILED : INIT]);
 185                                         XClearWindow(dpy, locks[screen]->win);
 186                                 }
 187                         }
 188                         llen = len;
 189                 } else if (rr && ev.type == rrevbase + RRScreenChangeNotify) {
 190                         XRRScreenChangeNotifyEvent *rre = (XRRScreenChangeNotifyEvent*)&ev;
 191                         for (screen = 0; screen < nscreens; screen++) {
 192                                 if (locks[screen]->win == rre->window) {
 193                                         XResizeWindow(dpy, locks[screen]->win, rre->width, rre->height);
 194                                         XClearWindow(dpy, locks[screen]->win);
 195                                 }
 196                         }
 197                 } else for (screen = 0; screen < nscreens; screen++)
 198                         XRaiseWindow(dpy, locks[screen]->win);
 199         }
 200 }
 201
 202 static void
 203 unlockscreen(Display *dpy, Lock *lock)
 204 {
 205         if(dpy == NULL || lock == NULL)
 206                 return;
 207
 208         XUngrabPointer(dpy, CurrentTime);
 209         XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, NUMCOLS, 0);
 210         XFreePixmap(dpy, lock->pmap);
 211         XDestroyWindow(dpy, lock->win);
 212
 213         free(lock);
 214 }
 215
 216 static Lock *
 217 lockscreen(Display *dpy, int screen)
 218 {
 219         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
 220         unsigned int len;
 221         int i;
 222         Lock *lock;
 223         XColor color, dummy;
 224         XSetWindowAttributes wa;
 225         Cursor invisible;
 226
 227         if (dpy == NULL || screen < 0)
 228                 return NULL;
 229
 230         lock = malloc(sizeof(Lock));
 231         if (lock == NULL)
 232                 return NULL;
 233
 234         lock->screen = screen;
 235
 236         lock->root = RootWindow(dpy, lock->screen);
 237
 238         for (i = 0; i < NUMCOLS; i++) {
 239                 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), colorname[i], &color, &dummy);
 240                 lock->colors[i] = color.pixel;
 241         }
 242
 243         /* init */
 244         wa.override_redirect = 1;
 245         wa.background_pixel = lock->colors[INIT];
 246         lock->win = XCreateWindow(dpy, lock->root, 0, 0, DisplayWidth(dpy, lock->screen), DisplayHeight(dpy, lock->screen),
 247                                   0, DefaultDepth(dpy, lock->screen), CopyFromParent,
 248                                   DefaultVisual(dpy, lock->screen), CWOverrideRedirect | CWBackPixel, &wa);
 249         lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
 250         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
 251         XDefineCursor(dpy, lock->win, invisible);
 252         XMapRaised(dpy, lock->win);
 253         if (rr)
 254                 XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
 255         for (len = 1000; len; len--) {
 256                 if (XGrabPointer(dpy, lock->root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
 257                     GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
 258                         break;
 259                 usleep(1000);
 260         }
 261         if (running && (len > 0)) {
 262                 for (len = 1000; len; len--) {
 263                         if (XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync, CurrentTime) == GrabSuccess)
 264                                 break;
 265                         usleep(1000);
 266                 }
 267         }
 268
 269         running &= (len > 0);
 270         if (!running) {
 271                 unlockscreen(dpy, lock);
 272                 lock = NULL;
 273         }
 274         else {
 275                 XSelectInput(dpy, lock->root, SubstructureNotifyMask);
 276         }
 277
 278         return lock;
 279 }
 280
 281 static void
 282 usage(void)
 283 {
 284         fprintf(stderr, "usage: slock [-v]\n");
 285         exit(1);
 286 }
 287
 288 int
 289 main(int argc, char **argv) {
 290 #ifndef HAVE_BSD_AUTH
 291         const char *pws;
 292 #endif
 293         Display *dpy;
 294         int screen;
 295
 296         if ((argc == 2) && !strcmp("-v", argv[1]))
 297                 die("slock-%s, © 2006-2015 slock engineers\n", VERSION);
 298         else if (argc != 1)
 299                 usage();
 300
 301 #ifdef __linux__
 302         dontkillme();
 303 #endif
 304
 305         if (!getpwuid(getuid()))
 306                 die("slock: no passwd entry for you\n");
 307
 308 #ifndef HAVE_BSD_AUTH
 309         pws = getpw();
 310 #endif
 311
 312         if (!(dpy = XOpenDisplay(0)))
 313                 die("slock: cannot open display\n");
 314         rr = XRRQueryExtension(dpy, &rrevbase, &rrerrbase);
 315         /* Get the number of screens in display "dpy" and blank them all. */
 316         nscreens = ScreenCount(dpy);
 317         locks = malloc(sizeof(Lock *) * nscreens);
 318         if (locks == NULL)
 319                 die("slock: malloc: %s\n", strerror(errno));
 320         int nlocks = 0;
 321         for (screen = 0; screen < nscreens; screen++) {
 322                 if ( (locks[screen] = lockscreen(dpy, screen)) != NULL)
 323                         nlocks++;
 324         }
 325         XSync(dpy, False);
 326
 327         /* Did we actually manage to lock something? */
 328         if (nlocks == 0) { /* nothing to protect */
 329                 free(locks);
 330                 XCloseDisplay(dpy);
 331                 return 1;
 332         }
 333
 334         /* Everything is now blank. Now wait for the correct password. */
 335 #ifdef HAVE_BSD_AUTH
 336         readpw(dpy);
 337 #else
 338         readpw(dpy, pws);
 339 #endif
 340
 341         /* Password ok, unlock everything and quit. */
 342         for (screen = 0; screen < nscreens; screen++)
 343                 unlockscreen(dpy, locks[screen]);
 344
 345         free(locks);
 346         XCloseDisplay(dpy);
 347
 348         return 0;
 349 }