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