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 #ifdef __linux__
  48 #include <fcntl.h>
  49
  50 static void
  51 dontkillme(void) {
  52         int fd;
  53
  54         fd = open("/proc/self/oom_score_adj", O_WRONLY);
  55         if (fd < 0 && errno == ENOENT)
  56                 return;
  57         if (fd < 0 || write(fd, "-1000\n", 6) != 6 || close(fd) != 0)
  58                 die("cannot disable the out-of-memory killer for this process\n");
  59 }
  60 #endif
  61
  62 #ifndef HAVE_BSD_AUTH
  63 static const char *
  64 getpw(void) { /* only run as root */
  65         const char *rval;
  66         struct passwd *pw;
  67
  68         errno = 0;
  69         pw = getpwuid(getuid());
  70         if (!pw) {
  71                 if (errno)
  72                         die("slock: getpwuid: %s\n", strerror(errno));
  73                 else
  74                         die("slock: cannot retrieve password entry (make sure to suid or sgid slock)\n");
  75         }
  76         endpwent();
  77         rval =  pw->pw_passwd;
  78
  79 #if HAVE_SHADOW_H
  80         if (rval[0] == 'x' && rval[1] == '\0') {
  81                 struct spwd *sp;
  82                 sp = getspnam(getenv("USER"));
  83                 if(!sp)
  84                         die("slock: cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
  85                 endspent();
  86                 rval = sp->sp_pwdp;
  87         }
  88 #endif
  89
  90         /* drop privileges */
  91         if (geteuid() == 0
  92            && ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
  93                 die("slock: cannot drop privileges\n");
  94         return rval;
  95 }
  96 #endif
  97
  98 static void
  99 #ifdef HAVE_BSD_AUTH
 100 readpw(Display *dpy)
 101 #else
 102 readpw(Display *dpy, const char *pws)
 103 #endif
 104 {
 105         char buf[32], passwd[256];
 106         int num, screen;
 107         unsigned int len, llen;
 108         KeySym ksym;
 109         XEvent ev;
 110
 111         len = llen = 0;
 112         running = True;
 113
 114         /* As "slock" stands for "Simple X display locker", the DPMS settings
 115          * had been removed and you can set it with "xset" or some other
 116          * utility. This way the user can easily set a customized DPMS
 117          * timeout. */
 118         while(running && !XNextEvent(dpy, &ev)) {
 119                 if(ev.type == KeyPress) {
 120                         buf[0] = 0;
 121                         num = XLookupString(&ev.xkey, buf, sizeof buf, &ksym, 0);
 122                         if(IsKeypadKey(ksym)) {
 123                                 if(ksym == XK_KP_Enter)
 124                                         ksym = XK_Return;
 125                                 else if(ksym >= XK_KP_0 && ksym <= XK_KP_9)
 126                                         ksym = (ksym - XK_KP_0) + XK_0;
 127                         }
 128                         if(IsFunctionKey(ksym) || IsKeypadKey(ksym)
 129                                         || IsMiscFunctionKey(ksym) || IsPFKey(ksym)
 130                                         || IsPrivateKeypadKey(ksym))
 131                                 continue;
 132                         switch(ksym) {
 133                         case XK_Return:
 134                                 passwd[len] = 0;
 135 #ifdef HAVE_BSD_AUTH
 136                                 running = !auth_userokay(getlogin(), NULL, "auth-xlock", passwd);
 137 #else
 138                                 running = !!strcmp(crypt(passwd, pws), pws);
 139 #endif
 140                                 if(running)
 141                                         XBell(dpy, 100);
 142                                 len = 0;
 143                                 break;
 144                         case XK_Escape:
 145                                 len = 0;
 146                                 break;
 147                         case XK_BackSpace:
 148                                 if(len)
 149                                         --len;
 150                                 break;
 151                         default:
 152                                 if(num && !iscntrl((int) buf[0]) && (len + num < sizeof passwd)) {
 153                                         memcpy(passwd + len, buf, num);
 154                                         len += num;
 155                                 }
 156                                 break;
 157                         }
 158                         if(llen == 0 && len != 0) {
 159                                 for(screen = 0; screen < nscreens; screen++) {
 160                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[1]);
 161                                         XClearWindow(dpy, locks[screen]->win);
 162                                 }
 163                         } else if(llen != 0 && len == 0) {
 164                                 for(screen = 0; screen < nscreens; screen++) {
 165                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[0]);
 166                                         XClearWindow(dpy, locks[screen]->win);
 167                                 }
 168                         }
 169                         llen = len;
 170                 }
 171                 else for(screen = 0; screen < nscreens; screen++)
 172                         XRaiseWindow(dpy, locks[screen]->win);
 173         }
 174 }
 175
 176 static void
 177 unlockscreen(Display *dpy, Lock *lock) {
 178         if(dpy == NULL || lock == NULL)
 179                 return;
 180
 181         XUngrabPointer(dpy, CurrentTime);
 182         XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, 2, 0);
 183         XFreePixmap(dpy, lock->pmap);
 184         XDestroyWindow(dpy, lock->win);
 185
 186         free(lock);
 187 }
 188
 189 static Lock *
 190 lockscreen(Display *dpy, int screen) {
 191         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
 192         unsigned int len;
 193         Lock *lock;
 194         XColor color, dummy;
 195         XSetWindowAttributes wa;
 196         Cursor invisible;
 197
 198         if(dpy == NULL || screen < 0)
 199                 return NULL;
 200
 201         lock = malloc(sizeof(Lock));
 202         if(lock == NULL)
 203                 return NULL;
 204
 205         lock->screen = screen;
 206
 207         lock->root = RootWindow(dpy, lock->screen);
 208
 209         /* init */
 210         wa.override_redirect = 1;
 211         wa.background_pixel = BlackPixel(dpy, lock->screen);
 212         lock->win = XCreateWindow(dpy, lock->root, 0, 0, DisplayWidth(dpy, lock->screen), DisplayHeight(dpy, lock->screen),
 213                         0, DefaultDepth(dpy, lock->screen), CopyFromParent,
 214                         DefaultVisual(dpy, lock->screen), CWOverrideRedirect | CWBackPixel, &wa);
 215         XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), COLOR2, &color, &dummy);
 216         lock->colors[1] = color.pixel;
 217         XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), COLOR1, &color, &dummy);
 218         lock->colors[0] = color.pixel;
 219         lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
 220         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
 221         XDefineCursor(dpy, lock->win, invisible);
 222         XMapRaised(dpy, lock->win);
 223         for(len = 1000; len; len--) {
 224                 if(XGrabPointer(dpy, lock->root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
 225                         GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
 226                         break;
 227                 usleep(1000);
 228         }
 229         if(running && (len > 0)) {
 230                 for(len = 1000; len; len--) {
 231                         if(XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync, CurrentTime)
 232                                 == GrabSuccess)
 233                                 break;
 234                         usleep(1000);
 235                 }
 236         }
 237
 238         running &= (len > 0);
 239         if(!running) {
 240                 unlockscreen(dpy, lock);
 241                 lock = NULL;
 242         }
 243         else
 244                 XSelectInput(dpy, lock->root, SubstructureNotifyMask);
 245
 246         return lock;
 247 }
 248
 249 static void
 250 usage(void) {
 251         fprintf(stderr, "usage: slock [-v]\n");
 252         exit(EXIT_FAILURE);
 253 }
 254
 255 int
 256 main(int argc, char **argv) {
 257 #ifndef HAVE_BSD_AUTH
 258         const char *pws;
 259 #endif
 260         Display *dpy;
 261         int screen;
 262
 263         if((argc == 2) && !strcmp("-v", argv[1]))
 264                 die("slock-%s, © 2006-2012 Anselm R Garbe\n", VERSION);
 265         else if(argc != 1)
 266                 usage();
 267
 268 #ifdef __linux__
 269         dontkillme();
 270 #endif
 271
 272         if(!getpwuid(getuid()))
 273                 die("slock: no passwd entry for you\n");
 274
 275 #ifndef HAVE_BSD_AUTH
 276         pws = getpw();
 277 #endif
 278
 279         if(!(dpy = XOpenDisplay(0)))
 280                 die("slock: cannot open display\n");
 281         /* Get the number of screens in display "dpy" and blank them all. */
 282         nscreens = ScreenCount(dpy);
 283         locks = malloc(sizeof(Lock *) * nscreens);
 284         if(locks == NULL)
 285                 die("slock: malloc: %s\n", strerror(errno));
 286         int nlocks = 0;
 287         for(screen = 0; screen < nscreens; screen++) {
 288                 if ( (locks[screen] = lockscreen(dpy, screen)) != NULL)
 289                         nlocks++;
 290         }
 291         XSync(dpy, False);
 292
 293         /* Did we actually manage to lock something? */
 294         if (nlocks == 0) { // nothing to protect
 295                 free(locks);
 296                 XCloseDisplay(dpy);
 297                 return 1;
 298         }
 299
 300         /* Everything is now blank. Now wait for the correct password. */
 301 #ifdef HAVE_BSD_AUTH
 302         readpw(dpy);
 303 #else
 304         readpw(dpy, pws);
 305 #endif
 306
 307         /* Password ok, unlock everything and quit. */
 308         for(screen = 0; screen < nscreens; screen++)
 309                 unlockscreen(dpy, locks[screen]);
 310
 311         free(locks);
 312         XCloseDisplay(dpy);
 313
 314         return 0;
 315 }