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 #include "config.h"
  26
  27 typedef struct {
  28         int screen;
  29         Window root, win;
  30         Pixmap pmap;
  31         unsigned long colors[2];
  32 } Lock;
  33
  34 static Lock **locks;
  35 static int nscreens;
  36 static Bool running = True;
  37
  38 static void
  39 die(const char *errstr, ...)
  40 {
  41         va_list ap;
  42
  43         va_start(ap, errstr);
  44         vfprintf(stderr, errstr, ap);
  45         va_end(ap);
  46         exit(1);
  47 }
  48
  49 #ifdef __linux__
  50 #include <fcntl.h>
  51
  52 static void
  53 dontkillme(void)
  54 {
  55         int fd;
  56
  57         fd = open("/proc/self/oom_score_adj", O_WRONLY);
  58         if (fd < 0 && errno == ENOENT)
  59                 return;
  60         if (fd < 0 || write(fd, "-1000\n", 6) != 6 || close(fd) != 0)
  61                 die("cannot disable the out-of-memory killer for this process\n");
  62 }
  63 #endif
  64
  65 #ifndef HAVE_BSD_AUTH
  66 /* only run as root */
  67 static const char *
  68 getpw(void)
  69 {
  70         const char *rval;
  71         struct passwd *pw;
  72
  73         errno = 0;
  74         pw = getpwuid(getuid());
  75         if (!pw) {
  76                 if (errno)
  77                         die("slock: getpwuid: %s\n", strerror(errno));
  78                 else
  79                         die("slock: cannot retrieve password entry\n");
  80         }
  81         rval =  pw->pw_passwd;
  82
  83 #if HAVE_SHADOW_H
  84         if (rval[0] == 'x' && rval[1] == '\0') {
  85                 struct spwd *sp;
  86                 sp = getspnam(getenv("USER"));
  87                 if (!sp)
  88                         die("slock: cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
  89                 rval = sp->sp_pwdp;
  90         }
  91 #endif
  92
  93         /* drop privileges */
  94         if (geteuid() == 0 &&
  95             ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
  96                 die("slock: cannot drop privileges\n");
  97         return rval;
  98 }
  99 #endif
 100
 101 static void
 102 #ifdef HAVE_BSD_AUTH
 103 readpw(Display *dpy)
 104 #else
 105 readpw(Display *dpy, const char *pws)
 106 #endif
 107 {
 108         char buf[32], passwd[256];
 109         int num, screen;
 110         unsigned int len, llen;
 111         KeySym ksym;
 112         XEvent ev;
 113
 114         len = llen = 0;
 115         running = True;
 116
 117         /* As "slock" stands for "Simple X display locker", the DPMS settings
 118          * had been removed and you can set it with "xset" or some other
 119          * utility. This way the user can easily set a customized DPMS
 120          * timeout. */
 121         while (running && !XNextEvent(dpy, &ev)) {
 122                 if (ev.type == KeyPress) {
 123                         buf[0] = 0;
 124                         num = XLookupString(&ev.xkey, buf, sizeof buf, &ksym, 0);
 125                         if (IsKeypadKey(ksym)) {
 126                                 if (ksym == XK_KP_Enter)
 127                                         ksym = XK_Return;
 128                                 else if (ksym >= XK_KP_0 && ksym <= XK_KP_9)
 129                                         ksym = (ksym - XK_KP_0) + XK_0;
 130                         }
 131                         if (IsFunctionKey(ksym) ||
 132                             IsKeypadKey(ksym) ||
 133                             IsMiscFunctionKey(ksym) ||
 134                             IsPFKey(ksym) ||
 135                             IsPrivateKeypadKey(ksym))
 136                                 continue;
 137                         switch (ksym) {
 138                         case XK_Return:
 139                                 passwd[len] = 0;
 140 #ifdef HAVE_BSD_AUTH
 141                                 running = !auth_userokay(getlogin(), NULL, "auth-xlock", passwd);
 142 #else
 143                                 running = !!strcmp(crypt(passwd, pws), pws);
 144 #endif
 145                                 if (running)
 146                                         XBell(dpy, 100);
 147                                 len = 0;
 148                                 break;
 149                         case XK_Escape:
 150                                 len = 0;
 151                                 break;
 152                         case XK_BackSpace:
 153                                 if (len)
 154                                         --len;
 155                                 break;
 156                         default:
 157                                 if (num && !iscntrl((int) buf[0]) && (len + num < sizeof passwd)) {
 158                                         memcpy(passwd + len, buf, num);
 159                                         len += num;
 160                                 }
 161                                 break;
 162                         }
 163                         if (llen == 0 && len != 0) {
 164                                 for (screen = 0; screen < nscreens; screen++) {
 165                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[1]);
 166                                         XClearWindow(dpy, locks[screen]->win);
 167                                 }
 168                         } else if (llen != 0 && len == 0) {
 169                                 for (screen = 0; screen < nscreens; screen++) {
 170                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[0]);
 171                                         XClearWindow(dpy, locks[screen]->win);
 172                                 }
 173                         }
 174                         llen = len;
 175                 }
 176                 else for (screen = 0; screen < nscreens; screen++)
 177                         XRaiseWindow(dpy, locks[screen]->win);
 178         }
 179 }
 180
 181 static void
 182 unlockscreen(Display *dpy, Lock *lock)
 183 {
 184         if(dpy == NULL || lock == NULL)
 185                 return;
 186
 187         XUngrabPointer(dpy, CurrentTime);
 188         XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, 2, 0);
 189         XFreePixmap(dpy, lock->pmap);
 190         XDestroyWindow(dpy, lock->win);
 191
 192         free(lock);
 193 }
 194
 195 static Lock *
 196 lockscreen(Display *dpy, int screen)
 197 {
 198         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
 199         unsigned int len;
 200         Lock *lock;
 201         XColor color, dummy;
 202         XSetWindowAttributes wa;
 203         Cursor invisible;
 204
 205         if (dpy == NULL || screen < 0)
 206                 return NULL;
 207
 208         lock = malloc(sizeof(Lock));
 209         if (lock == NULL)
 210                 return NULL;
 211
 212         lock->screen = screen;
 213
 214         lock->root = RootWindow(dpy, lock->screen);
 215
 216         /* init */
 217         wa.override_redirect = 1;
 218         wa.background_pixel = BlackPixel(dpy, lock->screen);
 219         lock->win = XCreateWindow(dpy, lock->root, 0, 0, DisplayWidth(dpy, lock->screen), DisplayHeight(dpy, lock->screen),
 220                                   0, DefaultDepth(dpy, lock->screen), CopyFromParent,
 221                                   DefaultVisual(dpy, lock->screen), CWOverrideRedirect | CWBackPixel, &wa);
 222         XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), COLOR2, &color, &dummy);
 223         lock->colors[1] = color.pixel;
 224         XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), COLOR1, &color, &dummy);
 225         lock->colors[0] = color.pixel;
 226         lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
 227         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
 228         XDefineCursor(dpy, lock->win, invisible);
 229         XMapRaised(dpy, lock->win);
 230         for (len = 1000; len; len--) {
 231                 if (XGrabPointer(dpy, lock->root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
 232                     GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
 233                         break;
 234                 usleep(1000);
 235         }
 236         if (running && (len > 0)) {
 237                 for (len = 1000; len; len--) {
 238                         if (XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync, CurrentTime) == GrabSuccess)
 239                                 break;
 240                         usleep(1000);
 241                 }
 242         }
 243
 244         running &= (len > 0);
 245         if (!running) {
 246                 unlockscreen(dpy, lock);
 247                 lock = NULL;
 248         }
 249         else {
 250                 XSelectInput(dpy, lock->root, SubstructureNotifyMask);
 251         }
 252
 253         return lock;
 254 }
 255
 256 static void
 257 usage(void)
 258 {
 259         fprintf(stderr, "usage: slock [-v]\n");
 260         exit(1);
 261 }
 262
 263 int
 264 main(int argc, char **argv) {
 265 #ifndef HAVE_BSD_AUTH
 266         const char *pws;
 267 #endif
 268         Display *dpy;
 269         int screen;
 270
 271         if ((argc == 2) && !strcmp("-v", argv[1]))
 272                 die("slock-%s, © 2006-2015 slock engineers\n", VERSION);
 273         else if (argc != 1)
 274                 usage();
 275
 276 #ifdef __linux__
 277         dontkillme();
 278 #endif
 279
 280         if (!getpwuid(getuid()))
 281                 die("slock: no passwd entry for you\n");
 282
 283 #ifndef HAVE_BSD_AUTH
 284         pws = getpw();
 285 #endif
 286
 287         if (!(dpy = XOpenDisplay(0)))
 288                 die("slock: cannot open display\n");
 289         /* Get the number of screens in display "dpy" and blank them all. */
 290         nscreens = ScreenCount(dpy);
 291         locks = malloc(sizeof(Lock *) * nscreens);
 292         if (locks == NULL)
 293                 die("slock: malloc: %s\n", strerror(errno));
 294         int nlocks = 0;
 295         for (screen = 0; screen < nscreens; screen++) {
 296                 if ( (locks[screen] = lockscreen(dpy, screen)) != NULL)
 297                         nlocks++;
 298         }
 299         XSync(dpy, False);
 300
 301         /* Did we actually manage to lock something? */
 302         if (nlocks == 0) { /* nothing to protect */
 303                 free(locks);
 304                 XCloseDisplay(dpy);
 305                 return 1;
 306         }
 307
 308         /* Everything is now blank. Now wait for the correct password. */
 309 #ifdef HAVE_BSD_AUTH
 310         readpw(dpy);
 311 #else
 312         readpw(dpy, pws);
 313 #endif
 314
 315         /* Password ok, unlock everything and quit. */
 316         for (screen = 0; screen < nscreens; screen++)
 317                 unlockscreen(dpy, locks[screen]);
 318
 319         free(locks);
 320         XCloseDisplay(dpy);
 321
 322         return 0;
 323 }