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