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/keysym.h>
  17 #include <X11/Xlib.h>
  18 #include <X11/Xutil.h>
  19
  20 #if HAVE_BSD_AUTH
  21 #include <login_cap.h>
  22 #include <bsd_auth.h>
  23 #endif
  24
  25 enum {
  26         INIT,
  27         INPUT,
  28         EMPTY,
  29         NUMCOLS
  30 };
  31
  32 #include "config.h"
  33
  34 typedef struct {
  35         int screen;
  36         Window root, win;
  37         Pixmap pmap;
  38         unsigned long colors[NUMCOLS];
  39 } Lock;
  40
  41 static Lock **locks;
  42 static int nscreens;
  43 static Bool running = True;
  44
  45 static void
  46 die(const char *errstr, ...)
  47 {
  48         va_list ap;
  49
  50         va_start(ap, errstr);
  51         vfprintf(stderr, errstr, ap);
  52         va_end(ap);
  53         exit(1);
  54 }
  55
  56 #ifdef __linux__
  57 #include <fcntl.h>
  58
  59 static void
  60 dontkillme(void)
  61 {
  62         int fd;
  63
  64         fd = open("/proc/self/oom_score_adj", O_WRONLY);
  65         if (fd < 0 && errno == ENOENT)
  66                 return;
  67         if (fd < 0 || write(fd, "-1000\n", 6) != 6 || close(fd) != 0)
  68                 die("cannot disable the out-of-memory killer for this process\n");
  69 }
  70 #endif
  71
  72 #ifndef HAVE_BSD_AUTH
  73 /* only run as root */
  74 static const char *
  75 getpw(void)
  76 {
  77         const char *rval;
  78         struct passwd *pw;
  79
  80         errno = 0;
  81         pw = getpwuid(getuid());
  82         if (!pw) {
  83                 if (errno)
  84                         die("slock: getpwuid: %s\n", strerror(errno));
  85                 else
  86                         die("slock: cannot retrieve password entry\n");
  87         }
  88         rval =  pw->pw_passwd;
  89
  90 #if HAVE_SHADOW_H
  91         if (rval[0] == 'x' && rval[1] == '\0') {
  92                 struct spwd *sp;
  93                 sp = getspnam(getenv("USER"));
  94                 if (!sp)
  95                         die("slock: cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
  96                 rval = sp->sp_pwdp;
  97         }
  98 #endif
  99
 100         /* drop privileges */
 101         if (geteuid() == 0 &&
 102             ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
 103                 die("slock: cannot drop privileges\n");
 104         return rval;
 105 }
 106 #endif
 107
 108 static void
 109 #ifdef HAVE_BSD_AUTH
 110 readpw(Display *dpy)
 111 #else
 112 readpw(Display *dpy, const char *pws)
 113 #endif
 114 {
 115         char buf[32], passwd[256];
 116         int num, screen;
 117         unsigned int len, llen;
 118         KeySym ksym;
 119         XEvent ev;
 120
 121         len = llen = 0;
 122         running = True;
 123
 124         /* As "slock" stands for "Simple X display locker", the DPMS settings
 125          * had been removed and you can set it with "xset" or some other
 126          * utility. This way the user can easily set a customized DPMS
 127          * timeout. */
 128         while (running && !XNextEvent(dpy, &ev)) {
 129                 if (ev.type == KeyPress) {
 130                         buf[0] = 0;
 131                         num = XLookupString(&ev.xkey, buf, sizeof buf, &ksym, 0);
 132                         if (IsKeypadKey(ksym)) {
 133                                 if (ksym == XK_KP_Enter)
 134                                         ksym = XK_Return;
 135                                 else if (ksym >= XK_KP_0 && ksym <= XK_KP_9)
 136                                         ksym = (ksym - XK_KP_0) + XK_0;
 137                         }
 138                         if (IsFunctionKey(ksym) ||
 139                             IsKeypadKey(ksym) ||
 140                             IsMiscFunctionKey(ksym) ||
 141                             IsPFKey(ksym) ||
 142                             IsPrivateKeypadKey(ksym))
 143                                 continue;
 144                         switch (ksym) {
 145                         case XK_Return:
 146                                 passwd[len] = 0;
 147 #ifdef HAVE_BSD_AUTH
 148                                 running = !auth_userokay(getlogin(), NULL, "auth-xlock", passwd);
 149 #else
 150                                 running = !!strcmp(crypt(passwd, pws), pws);
 151 #endif
 152                                 if (running)
 153                                         XBell(dpy, 100);
 154                                 len = 0;
 155                                 break;
 156                         case XK_Escape:
 157                                 len = 0;
 158                                 break;
 159                         case XK_BackSpace:
 160                                 if (len)
 161                                         --len;
 162                                 break;
 163                         default:
 164                                 if (num && !iscntrl((int) buf[0]) && (len + num < sizeof passwd)) {
 165                                         memcpy(passwd + len, buf, num);
 166                                         len += num;
 167                                 }
 168                                 break;
 169                         }
 170                         if (llen == 0 && len != 0) {
 171                                 for (screen = 0; screen < nscreens; screen++) {
 172                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[INPUT]);
 173                                         XClearWindow(dpy, locks[screen]->win);
 174                                 }
 175                         } else if (llen != 0 && len == 0) {
 176                                 for (screen = 0; screen < nscreens; screen++) {
 177                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[EMPTY]);
 178                                         XClearWindow(dpy, locks[screen]->win);
 179                                 }
 180                         }
 181                         llen = len;
 182                 }
 183                 else for (screen = 0; screen < nscreens; screen++)
 184                         XRaiseWindow(dpy, locks[screen]->win);
 185         }
 186 }
 187
 188 static void
 189 unlockscreen(Display *dpy, Lock *lock)
 190 {
 191         if(dpy == NULL || lock == NULL)
 192                 return;
 193
 194         XUngrabPointer(dpy, CurrentTime);
 195         XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, NUMCOLS, 0);
 196         XFreePixmap(dpy, lock->pmap);
 197         XDestroyWindow(dpy, lock->win);
 198
 199         free(lock);
 200 }
 201
 202 static Lock *
 203 lockscreen(Display *dpy, int screen)
 204 {
 205         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
 206         unsigned int len;
 207         int i;
 208         Lock *lock;
 209         XColor color, dummy;
 210         XSetWindowAttributes wa;
 211         Cursor invisible;
 212
 213         if (dpy == NULL || screen < 0)
 214                 return NULL;
 215
 216         lock = malloc(sizeof(Lock));
 217         if (lock == NULL)
 218                 return NULL;
 219
 220         lock->screen = screen;
 221
 222         lock->root = RootWindow(dpy, lock->screen);
 223
 224         for (i = 0; i < NUMCOLS; i++) {
 225                 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), colorname[i], &color, &dummy);
 226                 lock->colors[i] = color.pixel;
 227         }
 228
 229         /* init */
 230         wa.override_redirect = 1;
 231         wa.background_pixel = lock->colors[INIT];
 232         lock->win = XCreateWindow(dpy, lock->root, 0, 0, DisplayWidth(dpy, lock->screen), DisplayHeight(dpy, lock->screen),
 233                                   0, DefaultDepth(dpy, lock->screen), CopyFromParent,
 234                                   DefaultVisual(dpy, lock->screen), CWOverrideRedirect | CWBackPixel, &wa);
 235         lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
 236         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
 237         XDefineCursor(dpy, lock->win, invisible);
 238         XMapRaised(dpy, lock->win);
 239         for (len = 1000; len; len--) {
 240                 if (XGrabPointer(dpy, lock->root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
 241                     GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
 242                         break;
 243                 usleep(1000);
 244         }
 245         if (running && (len > 0)) {
 246                 for (len = 1000; len; len--) {
 247                         if (XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync, CurrentTime) == GrabSuccess)
 248                                 break;
 249                         usleep(1000);
 250                 }
 251         }
 252
 253         running &= (len > 0);
 254         if (!running) {
 255                 unlockscreen(dpy, lock);
 256                 lock = NULL;
 257         }
 258         else {
 259                 XSelectInput(dpy, lock->root, SubstructureNotifyMask);
 260         }
 261
 262         return lock;
 263 }
 264
 265 static void
 266 usage(void)
 267 {
 268         fprintf(stderr, "usage: slock [-v]\n");
 269         exit(1);
 270 }
 271
 272 int
 273 main(int argc, char **argv) {
 274 #ifndef HAVE_BSD_AUTH
 275         const char *pws;
 276 #endif
 277         Display *dpy;
 278         int screen;
 279
 280         if ((argc == 2) && !strcmp("-v", argv[1]))
 281                 die("slock-%s, © 2006-2015 slock engineers\n", VERSION);
 282         else if (argc != 1)
 283                 usage();
 284
 285 #ifdef __linux__
 286         dontkillme();
 287 #endif
 288
 289         if (!getpwuid(getuid()))
 290                 die("slock: no passwd entry for you\n");
 291
 292 #ifndef HAVE_BSD_AUTH
 293         pws = getpw();
 294 #endif
 295
 296         if (!(dpy = XOpenDisplay(0)))
 297                 die("slock: cannot open display\n");
 298         /* Get the number of screens in display "dpy" and blank them all. */
 299         nscreens = ScreenCount(dpy);
 300         locks = malloc(sizeof(Lock *) * nscreens);
 301         if (locks == NULL)
 302                 die("slock: malloc: %s\n", strerror(errno));
 303         int nlocks = 0;
 304         for (screen = 0; screen < nscreens; screen++) {
 305                 if ( (locks[screen] = lockscreen(dpy, screen)) != NULL)
 306                         nlocks++;
 307         }
 308         XSync(dpy, False);
 309
 310         /* Did we actually manage to lock something? */
 311         if (nlocks == 0) { /* nothing to protect */
 312                 free(locks);
 313                 XCloseDisplay(dpy);
 314                 return 1;
 315         }
 316
 317         /* Everything is now blank. Now wait for the correct password. */
 318 #ifdef HAVE_BSD_AUTH
 319         readpw(dpy);
 320 #else
 321         readpw(dpy, pws);
 322 #endif
 323
 324         /* Password ok, unlock everything and quit. */
 325         for (screen = 0; screen < nscreens; screen++)
 326                 unlockscreen(dpy, locks[screen]);
 327
 328         free(locks);
 329         XCloseDisplay(dpy);
 330
 331         return 0;
 332 }