slock.c

   1
   2 /* See LICENSE file for license details. */
   3 #define _XOPEN_SOURCE 500
   4 #if HAVE_SHADOW_H
   5 #include <shadow.h>
   6 #endif
   7
   8 #include <ctype.h>
   9 #include <errno.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 <sys/types.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 typedef struct {
  27         int screen;
  28         Window root, win;
  29         Pixmap pmap;
  30         unsigned long colors[2];
  31 } Lock;
  32
  33 static Lock **locks;
  34 static int nscreens;
  35 static Bool running = True;
  36
  37 static void
  38 die(const char *errstr, ...) {
  39         va_list ap;
  40
  41         va_start(ap, errstr);
  42         vfprintf(stderr, errstr, ap);
  43         va_end(ap);
  44         exit(EXIT_FAILURE);
  45 }
  46
  47 #ifndef HAVE_BSD_AUTH
  48 static const char *
  49 getpw(void) { /* only run as root */
  50         const char *rval;
  51         struct passwd *pw;
  52
  53         pw = getpwuid(getuid());
  54         if(!pw)
  55                 die("slock: cannot retrieve password entry (make sure to suid or sgid slock)");
  56         endpwent();
  57         rval =  pw->pw_passwd;
  58
  59 #if HAVE_SHADOW_H
  60         if (strlen(rval) >= 1) { /* kludge, assumes pw placeholder entry has len >= 1 */
  61                 struct spwd *sp;
  62                 sp = getspnam(getenv("USER"));
  63                 if(!sp)
  64                         die("slock: cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
  65                 endspent();
  66                 rval = sp->sp_pwdp;
  67         }
  68 #endif
  69
  70         /* drop privileges */
  71         if(setgid(pw->pw_gid) < 0 || setuid(pw->pw_uid) < 0)
  72                 die("slock: cannot drop privileges");
  73         return rval;
  74 }
  75 #endif
  76
  77 static void
  78 #ifdef HAVE_BSD_AUTH
  79 readpw(Display *dpy)
  80 #else
  81 readpw(Display *dpy, const char *pws)
  82 #endif
  83 {
  84         char buf[32], passwd[256];
  85         int num, screen;
  86         unsigned int len, llen;
  87         KeySym ksym;
  88         XEvent ev;
  89
  90         len = llen = 0;
  91         running = True;
  92
  93         /* As "slock" stands for "Simple X display locker", the DPMS settings
  94          * had been removed and you can set it with "xset" or some other
  95          * utility. This way the user can easily set a customized DPMS
  96          * timeout. */
  97         while(running && !XNextEvent(dpy, &ev)) {
  98                 if(ev.type == KeyPress) {
  99                         buf[0] = 0;
 100                         num = XLookupString(&ev.xkey, buf, sizeof buf, &ksym, 0);
 101                         if(IsKeypadKey(ksym)) {
 102                                 if(ksym == XK_KP_Enter)
 103                                         ksym = XK_Return;
 104                                 else if(ksym >= XK_KP_0 && ksym <= XK_KP_9)
 105                                         ksym = (ksym - XK_KP_0) + XK_0;
 106                         }
 107                         if(IsFunctionKey(ksym) || IsKeypadKey(ksym)
 108                                         || IsMiscFunctionKey(ksym) || IsPFKey(ksym)
 109                                         || IsPrivateKeypadKey(ksym))
 110                                 continue;
 111                         switch(ksym) {
 112                         case XK_Return:
 113                                 passwd[len] = 0;
 114 #ifdef HAVE_BSD_AUTH
 115                                 running = !auth_userokay(getlogin(), NULL, "auth-xlock", passwd);
 116 #else
 117                                 running = strcmp(crypt(passwd, pws), pws);
 118 #endif
 119                                 if(running != False)
 120                                         XBell(dpy, 100);
 121                                 len = 0;
 122                                 break;
 123                         case XK_Escape:
 124                                 len = 0;
 125                                 break;
 126                         case XK_BackSpace:
 127                                 if(len)
 128                                         --len;
 129                                 break;
 130                         default:
 131                                 if(num && !iscntrl((int) buf[0]) && (len + num < sizeof passwd)) {
 132                                         memcpy(passwd + len, buf, num);
 133                                         len += num;
 134                                 }
 135                                 break;
 136                         }
 137                         if(llen == 0 && len != 0) {
 138                                 for(screen = 0; screen < nscreens; screen++) {
 139                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[1]);
 140                                         XClearWindow(dpy, locks[screen]->win);
 141                                 }
 142                         } else if(llen != 0 && len == 0) {
 143                                 for(screen = 0; screen < nscreens; screen++) {
 144                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[0]);
 145                                         XClearWindow(dpy, locks[screen]->win);
 146                                 }
 147                         }
 148                         llen = len;
 149                 }
 150                 else for(screen = 0; screen < nscreens; screen++)
 151                         XRaiseWindow(dpy, locks[screen]->win);
 152         }
 153 }
 154
 155 static void
 156 unlockscreen(Display *dpy, Lock *lock) {
 157         if(dpy == NULL || lock == NULL)
 158                 return;
 159
 160         XUngrabPointer(dpy, CurrentTime);
 161         XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, 2, 0);
 162         XFreePixmap(dpy, lock->pmap);
 163         XDestroyWindow(dpy, lock->win);
 164
 165         free(lock);
 166 }
 167
 168 static Lock *
 169 lockscreen(Display *dpy, int screen) {
 170         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
 171         unsigned int len;
 172         Lock *lock;
 173         XColor color, dummy;
 174         XSetWindowAttributes wa;
 175         Cursor invisible;
 176
 177         if(dpy == NULL || screen < 0)
 178                 return NULL;
 179
 180         lock = malloc(sizeof(Lock));
 181         if(lock == NULL)
 182                 return NULL;
 183
 184         lock->screen = screen;
 185
 186         lock->root = RootWindow(dpy, lock->screen);
 187
 188         /* init */
 189         wa.override_redirect = 1;
 190         wa.background_pixel = BlackPixel(dpy, lock->screen);
 191         lock->win = XCreateWindow(dpy, lock->root, 0, 0, DisplayWidth(dpy, lock->screen), DisplayHeight(dpy, lock->screen),
 192                         0, DefaultDepth(dpy, lock->screen), CopyFromParent,
 193                         DefaultVisual(dpy, lock->screen), CWOverrideRedirect | CWBackPixel, &wa);
 194         XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), COLOR2, &color, &dummy);
 195         lock->colors[1] = color.pixel;
 196         XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), COLOR1, &color, &dummy);
 197         lock->colors[0] = color.pixel;
 198         lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
 199         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
 200         XDefineCursor(dpy, lock->win, invisible);
 201         XMapRaised(dpy, lock->win);
 202         for(len = 1000; len; len--) {
 203                 if(XGrabPointer(dpy, lock->root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
 204                         GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
 205                         break;
 206                 usleep(1000);
 207         }
 208         if(running && (len > 0)) {
 209                 for(len = 1000; len; len--) {
 210                         if(XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync, CurrentTime)
 211                                 == GrabSuccess)
 212                                 break;
 213                         usleep(1000);
 214                 }
 215         }
 216
 217         running &= (len > 0);
 218         if(!running) {
 219                 unlockscreen(dpy, lock);
 220                 lock = NULL;
 221         }
 222         else
 223                 XSelectInput(dpy, lock->root, SubstructureNotifyMask);
 224
 225         return lock;
 226 }
 227
 228 static void
 229 usage(void) {
 230         fprintf(stderr, "usage: slock [-v]\n");
 231         exit(EXIT_FAILURE);
 232 }
 233
 234 int
 235 main(int argc, char **argv) {
 236 #ifndef HAVE_BSD_AUTH
 237         const char *pws;
 238 #endif
 239         Display *dpy;
 240         int screen;
 241
 242         if((argc == 2) && !strcmp("-v", argv[1]))
 243                 die("slock-%s, © 2006-2012 Anselm R Garbe\n", VERSION);
 244         else if(argc != 1)
 245                 usage();
 246
 247         if(!getpwuid(getuid()))
 248                 die("slock: no passwd entry for you");
 249
 250 #ifndef HAVE_BSD_AUTH
 251         pws = getpw();
 252 #endif
 253
 254         if(!(dpy = XOpenDisplay(0)))
 255                 die("slock: cannot open display");
 256         /* Get the number of screens in display "dpy" and blank them all. */
 257         nscreens = ScreenCount(dpy);
 258         locks = malloc(sizeof(Lock *) * nscreens);
 259         if(locks == NULL)
 260                 die("slock: malloc: %s", strerror(errno));
 261         int nlocks = 0;
 262         for(screen = 0; screen < nscreens; screen++) {
 263                 if ( (locks[screen] = lockscreen(dpy, screen)) != NULL)
 264                         nlocks++;
 265         }
 266         XSync(dpy, False);
 267
 268         /* Did we actually manage to lock something? */
 269         if (nlocks == 0) { // nothing to protect
 270                 free(locks);
 271                 XCloseDisplay(dpy);
 272                 return 1;
 273         }
 274
 275         /* Everything is now blank. Now wait for the correct password. */
 276 #ifdef HAVE_BSD_AUTH
 277         readpw(dpy);
 278 #else
 279         readpw(dpy, pws);
 280 #endif
 281
 282         /* Password ok, unlock everything and quit. */
 283         for(screen = 0; screen < nscreens; screen++)
 284                 unlockscreen(dpy, locks[screen]);
 285
 286         free(locks);
 287         XCloseDisplay(dpy);
 288
 289         return 0;
 290 }