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, color;
 123         KeySym ksym;
 124         XEvent ev;
 125         static int oldc = INIT;
 126
 127         len = 0;
 128         running = True;
 129
 130         /* As "slock" stands for "Simple X display locker", the DPMS settings
 131          * had been removed and you can set it with "xset" or some other
 132          * utility. This way the user can easily set a customized DPMS
 133          * timeout. */
 134         while (running && !XNextEvent(dpy, &ev)) {
 135                 if (ev.type == KeyPress) {
 136                         buf[0] = 0;
 137                         num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0);
 138                         if (IsKeypadKey(ksym)) {
 139                                 if (ksym == XK_KP_Enter)
 140                                         ksym = XK_Return;
 141                                 else if (ksym >= XK_KP_0 && ksym <= XK_KP_9)
 142                                         ksym = (ksym - XK_KP_0) + XK_0;
 143                         }
 144                         if (IsFunctionKey(ksym) ||
 145                             IsKeypadKey(ksym) ||
 146                             IsMiscFunctionKey(ksym) ||
 147                             IsPFKey(ksym) ||
 148                             IsPrivateKeypadKey(ksym))
 149                                 continue;
 150                         switch (ksym) {
 151                         case XK_Return:
 152                                 passwd[len] = 0;
 153 #ifdef HAVE_BSD_AUTH
 154                                 running = !auth_userokay(getlogin(), NULL, "auth-xlock", passwd);
 155 #else
 156                                 running = !!strcmp(crypt(passwd, pws), pws);
 157 #endif
 158                                 if (running) {
 159                                         XBell(dpy, 100);
 160                                         failure = True;
 161                                 }
 162                                 len = 0;
 163                                 break;
 164                         case XK_Escape:
 165                                 len = 0;
 166                                 break;
 167                         case XK_BackSpace:
 168                                 if (len)
 169                                         --len;
 170                                 break;
 171                         default:
 172                                 if (num && !iscntrl((int) buf[0]) && (len + num < sizeof(passwd))) {
 173                                         memcpy(passwd + len, buf, num);
 174                                         len += num;
 175                                 }
 176                                 break;
 177                         }
 178                         color = len ? INPUT : (failure || failonclear ? FAILED : INIT);
 179                         if (oldc != color) {
 180                                 for (screen = 0; screen < nscreens; screen++) {
 181                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[color]);
 182                                         XClearWindow(dpy, locks[screen]->win);
 183                                 }
 184                                 oldc = color;
 185                         }
 186                 } else if (rr && ev.type == rrevbase + RRScreenChangeNotify) {
 187                         XRRScreenChangeNotifyEvent *rre = (XRRScreenChangeNotifyEvent*)&ev;
 188                         for (screen = 0; screen < nscreens; screen++) {
 189                                 if (locks[screen]->win == rre->window) {
 190                                         XResizeWindow(dpy, locks[screen]->win, rre->width, rre->height);
 191                                         XClearWindow(dpy, locks[screen]->win);
 192                                 }
 193                         }
 194                 } else for (screen = 0; screen < nscreens; screen++)
 195                         XRaiseWindow(dpy, locks[screen]->win);
 196         }
 197 }
 198
 199 static void
 200 unlockscreen(Display *dpy, Lock *lock)
 201 {
 202         if(dpy == NULL || lock == NULL)
 203                 return;
 204
 205         XUngrabPointer(dpy, CurrentTime);
 206         XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, NUMCOLS, 0);
 207         XFreePixmap(dpy, lock->pmap);
 208         XDestroyWindow(dpy, lock->win);
 209
 210         free(lock);
 211 }
 212
 213 static Lock *
 214 lockscreen(Display *dpy, int screen)
 215 {
 216         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
 217         unsigned int len;
 218         int i;
 219         Lock *lock;
 220         XColor color, dummy;
 221         XSetWindowAttributes wa;
 222         Cursor invisible;
 223
 224         if (dpy == NULL || screen < 0)
 225                 return NULL;
 226
 227         lock = malloc(sizeof(Lock));
 228         if (lock == NULL)
 229                 return NULL;
 230
 231         lock->screen = screen;
 232
 233         lock->root = RootWindow(dpy, lock->screen);
 234
 235         for (i = 0; i < NUMCOLS; i++) {
 236                 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), colorname[i], &color, &dummy);
 237                 lock->colors[i] = color.pixel;
 238         }
 239
 240         /* init */
 241         wa.override_redirect = 1;
 242         wa.background_pixel = lock->colors[INIT];
 243         lock->win = XCreateWindow(dpy, lock->root, 0, 0, DisplayWidth(dpy, lock->screen), DisplayHeight(dpy, lock->screen),
 244                                   0, DefaultDepth(dpy, lock->screen), CopyFromParent,
 245                                   DefaultVisual(dpy, lock->screen), CWOverrideRedirect | CWBackPixel, &wa);
 246         lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
 247         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
 248         XDefineCursor(dpy, lock->win, invisible);
 249         XMapRaised(dpy, lock->win);
 250         if (rr)
 251                 XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
 252         for (len = 1000; len; len--) {
 253                 if (XGrabPointer(dpy, lock->root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
 254                     GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
 255                         break;
 256                 usleep(1000);
 257         }
 258         if (running && (len > 0)) {
 259                 for (len = 1000; len; len--) {
 260                         if (XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync, CurrentTime) == GrabSuccess)
 261                                 break;
 262                         usleep(1000);
 263                 }
 264         }
 265
 266         running &= (len > 0);
 267         if (!running) {
 268                 unlockscreen(dpy, lock);
 269                 lock = NULL;
 270         }
 271         else {
 272                 XSelectInput(dpy, lock->root, SubstructureNotifyMask);
 273         }
 274
 275         return lock;
 276 }
 277
 278 static void
 279 usage(void)
 280 {
 281         fprintf(stderr, "usage: slock [-v]\n");
 282         exit(1);
 283 }
 284
 285 int
 286 main(int argc, char **argv) {
 287 #ifndef HAVE_BSD_AUTH
 288         const char *pws;
 289 #endif
 290         Display *dpy;
 291         int screen;
 292
 293         if ((argc == 2) && !strcmp("-v", argv[1]))
 294                 die("slock-%s, © 2006-2015 slock engineers\n", VERSION);
 295         else if (argc != 1)
 296                 usage();
 297
 298 #ifdef __linux__
 299         dontkillme();
 300 #endif
 301
 302         if (!getpwuid(getuid()))
 303                 die("slock: no passwd entry for you\n");
 304
 305 #ifndef HAVE_BSD_AUTH
 306         pws = getpw();
 307 #endif
 308
 309         if (!(dpy = XOpenDisplay(0)))
 310                 die("slock: cannot open display\n");
 311         rr = XRRQueryExtension(dpy, &rrevbase, &rrerrbase);
 312         /* Get the number of screens in display "dpy" and blank them all. */
 313         nscreens = ScreenCount(dpy);
 314         locks = malloc(sizeof(Lock *) * nscreens);
 315         if (locks == NULL)
 316                 die("slock: malloc: %s\n", strerror(errno));
 317         int nlocks = 0;
 318         for (screen = 0; screen < nscreens; screen++) {
 319                 if ( (locks[screen] = lockscreen(dpy, screen)) != NULL)
 320                         nlocks++;
 321         }
 322         XSync(dpy, False);
 323
 324         /* Did we actually manage to lock something? */
 325         if (nlocks == 0) { /* nothing to protect */
 326                 free(locks);
 327                 XCloseDisplay(dpy);
 328                 return 1;
 329         }
 330
 331         /* Everything is now blank. Now wait for the correct password. */
 332 #ifdef HAVE_BSD_AUTH
 333         readpw(dpy);
 334 #else
 335         readpw(dpy, pws);
 336 #endif
 337
 338         /* Password ok, unlock everything and quit. */
 339         for (screen = 0; screen < nscreens; screen++)
 340                 unlockscreen(dpy, locks[screen]);
 341
 342         free(locks);
 343         XCloseDisplay(dpy);
 344
 345         return 0;
 346 }