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 #include "arg.h"
  27 #include "util.h"
  28
  29 char *argv0;
  30
  31 enum {
  32         INIT,
  33         INPUT,
  34         FAILED,
  35         NUMCOLS
  36 };
  37
  38 #include "config.h"
  39
  40 typedef struct {
  41         int screen;
  42         Window root, win;
  43         Pixmap pmap;
  44         unsigned long colors[NUMCOLS];
  45 } Lock;
  46
  47 static Lock **locks;
  48 static int nscreens;
  49 static Bool running = True;
  50 static Bool failure = False;
  51 static Bool rr;
  52 static int rrevbase;
  53 static int rrerrbase;
  54
  55 static void
  56 die(const char *errstr, ...)
  57 {
  58         va_list ap;
  59
  60         va_start(ap, errstr);
  61         vfprintf(stderr, errstr, ap);
  62         va_end(ap);
  63         exit(1);
  64 }
  65
  66 #ifdef __linux__
  67 #include <fcntl.h>
  68
  69 static void
  70 dontkillme(void)
  71 {
  72         int fd;
  73
  74         fd = open("/proc/self/oom_score_adj", O_WRONLY);
  75         if (fd < 0 && errno == ENOENT) {
  76                 return;
  77         }
  78         if (fd < 0 || write(fd, "-1000\n", (sizeof("-1000\n") - 1)) !=
  79             (sizeof("-1000\n") - 1) || close(fd) != 0) {
  80                 die("can't tame the oom-killer. is suid or sgid set?\n");
  81         }
  82 }
  83 #endif
  84
  85 #ifndef HAVE_BSD_AUTH
  86 /* only run as root */
  87 static const char *
  88 getpw(void)
  89 {
  90         const char *rval;
  91         struct passwd *pw;
  92
  93         errno = 0;
  94         if (!(pw = getpwuid(getuid()))) {
  95                 if (errno)
  96                         die("getpwuid: %s\n", strerror(errno));
  97                 else
  98                         die("cannot retrieve password entry\n");
  99         }
 100         rval = pw->pw_passwd;
 101
 102 #if HAVE_SHADOW_H
 103         if (rval[0] == 'x' && rval[1] == '\0') {
 104                 struct spwd *sp;
 105                 if (!(sp = getspnam(getenv("USER"))))
 106                         die("cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
 107                 rval = sp->sp_pwdp;
 108         }
 109 #endif
 110
 111         /* drop privileges */
 112         if (geteuid() == 0 &&
 113             ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
 114                 die("cannot drop privileges\n");
 115         return rval;
 116 }
 117 #endif
 118
 119 static void
 120 #ifdef HAVE_BSD_AUTH
 121 readpw(Display *dpy)
 122 #else
 123 readpw(Display *dpy, const char *pws)
 124 #endif
 125 {
 126         char buf[32], passwd[256], *encrypted;
 127         int num, screen;
 128         unsigned int len, color;
 129         KeySym ksym;
 130         XEvent ev;
 131         static int oldc = INIT;
 132
 133         len = 0;
 134         running = True;
 135
 136         /* As "slock" stands for "Simple X display locker", the DPMS settings
 137          * had been removed and you can set it with "xset" or some other
 138          * utility. This way the user can easily set a customized DPMS
 139          * timeout. */
 140         while (running && !XNextEvent(dpy, &ev)) {
 141                 if (ev.type == KeyPress) {
 142                         explicit_bzero(&buf, sizeof(buf));
 143                         num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0);
 144                         if (IsKeypadKey(ksym)) {
 145                                 if (ksym == XK_KP_Enter)
 146                                         ksym = XK_Return;
 147                                 else if (ksym >= XK_KP_0 && ksym <= XK_KP_9)
 148                                         ksym = (ksym - XK_KP_0) + XK_0;
 149                         }
 150                         if (IsFunctionKey(ksym) ||
 151                             IsKeypadKey(ksym) ||
 152                             IsMiscFunctionKey(ksym) ||
 153                             IsPFKey(ksym) ||
 154                             IsPrivateKeypadKey(ksym))
 155                                 continue;
 156                         switch (ksym) {
 157                         case XK_Return:
 158                                 passwd[len] = 0;
 159 #ifdef HAVE_BSD_AUTH
 160                                 running = !auth_userokay(getlogin(), NULL, "auth-slock", passwd);
 161 #else
 162                                 errno = 0;
 163                                 if (!(encrypted = crypt(passwd, pws)))
 164                                         fprintf(stderr, "slock: crypt: %s\n", strerror(errno));
 165                                 else
 166                                         running = !!strcmp(encrypted, pws);
 167 #endif
 168                                 if (running) {
 169                                         XBell(dpy, 100);
 170                                         failure = True;
 171                                 }
 172                                 explicit_bzero(&passwd, sizeof(passwd));
 173                                 len = 0;
 174                                 break;
 175                         case XK_Escape:
 176                                 explicit_bzero(&passwd, sizeof(passwd));
 177                                 len = 0;
 178                                 break;
 179                         case XK_BackSpace:
 180                                 if (len)
 181                                         passwd[len--] = 0;
 182                                 break;
 183                         default:
 184                                 if (num && !iscntrl((int)buf[0]) && (len + num < sizeof(passwd))) {
 185                                         memcpy(passwd + len, buf, num);
 186                                         len += num;
 187                                 }
 188                                 break;
 189                         }
 190                         color = len ? INPUT : (failure || failonclear ? FAILED : INIT);
 191                         if (running && oldc != color) {
 192                                 for (screen = 0; screen < nscreens; screen++) {
 193                                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[color]);
 194                                         XClearWindow(dpy, locks[screen]->win);
 195                                 }
 196                                 oldc = color;
 197                         }
 198                 } else if (rr && ev.type == rrevbase + RRScreenChangeNotify) {
 199                         XRRScreenChangeNotifyEvent *rre = (XRRScreenChangeNotifyEvent*)&ev;
 200                         for (screen = 0; screen < nscreens; screen++) {
 201                                 if (locks[screen]->win == rre->window) {
 202                                         XResizeWindow(dpy, locks[screen]->win, rre->width, rre->height);
 203                                         XClearWindow(dpy, locks[screen]->win);
 204                                 }
 205                         }
 206                 } else for (screen = 0; screen < nscreens; screen++)
 207                         XRaiseWindow(dpy, locks[screen]->win);
 208         }
 209 }
 210
 211 static void
 212 unlockscreen(Display *dpy, Lock *lock)
 213 {
 214         if(dpy == NULL || lock == NULL)
 215                 return;
 216
 217         XUngrabPointer(dpy, CurrentTime);
 218         XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, NUMCOLS, 0);
 219         XFreePixmap(dpy, lock->pmap);
 220         XDestroyWindow(dpy, lock->win);
 221
 222         free(lock);
 223 }
 224
 225 static Lock *
 226 lockscreen(Display *dpy, int screen)
 227 {
 228         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
 229         int i;
 230         Lock *lock;
 231         XColor color, dummy;
 232         XSetWindowAttributes wa;
 233         Cursor invisible;
 234
 235         if (!running || dpy == NULL || screen < 0 || !(lock = malloc(sizeof(Lock))))
 236                 return NULL;
 237
 238         lock->screen = screen;
 239         lock->root = RootWindow(dpy, lock->screen);
 240
 241         for (i = 0; i < NUMCOLS; i++) {
 242                 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), colorname[i], &color, &dummy);
 243                 lock->colors[i] = color.pixel;
 244         }
 245
 246         /* init */
 247         wa.override_redirect = 1;
 248         wa.background_pixel = lock->colors[INIT];
 249         lock->win = XCreateWindow(dpy, lock->root, 0, 0, DisplayWidth(dpy, lock->screen), DisplayHeight(dpy, lock->screen),
 250                                   0, DefaultDepth(dpy, lock->screen), CopyFromParent,
 251                                   DefaultVisual(dpy, lock->screen), CWOverrideRedirect | CWBackPixel, &wa);
 252         lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
 253         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
 254         XDefineCursor(dpy, lock->win, invisible);
 255
 256         /* Try to grab mouse pointer *and* keyboard, else fail the lock */
 257         if (XGrabPointer(dpy, lock->root, False, ButtonPressMask |
 258             ButtonReleaseMask | PointerMotionMask, GrabModeAsync, GrabModeAsync,
 259             None, invisible, CurrentTime) != GrabSuccess) {
 260                 fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n", screen);
 261                 running = 0;
 262                 unlockscreen(dpy, lock);
 263                 return NULL;
 264         }
 265
 266         if (XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync,
 267             CurrentTime) != GrabSuccess) {
 268                 fprintf(stderr, "slock: unable to grab keyboard for screen %d\n", screen);
 269                 running = 0;
 270                 unlockscreen(dpy, lock);
 271                 return NULL;
 272         }
 273
 274         XMapRaised(dpy, lock->win);
 275         if (rr)
 276                 XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
 277
 278         XSelectInput(dpy, lock->root, SubstructureNotifyMask);
 279         return lock;
 280 }
 281
 282 static void
 283 usage(void)
 284 {
 285         die("usage: slock [-v] [cmd [arg ...]]\n");
 286 }
 287
 288 int
 289 main(int argc, char **argv) {
 290 #ifndef HAVE_BSD_AUTH
 291         const char *pws;
 292 #endif
 293         Display *dpy;
 294         int s, nlocks;
 295
 296         ARGBEGIN {
 297         case 'v':
 298                 fprintf(stderr, "slock-"VERSION"\n");
 299                 return 0;
 300         default:
 301                 usage();
 302         } ARGEND
 303
 304 #ifdef __linux__
 305         dontkillme();
 306 #endif
 307
 308         /* Check if the current user has a password entry */
 309         errno = 0;
 310         if (!getpwuid(getuid())) {
 311                 if (errno == 0)
 312                         die("slock: no password entry for current user\n");
 313                 else
 314                         die("slock: getpwuid: %s\n", strerror(errno));
 315         }
 316
 317 #ifndef HAVE_BSD_AUTH
 318         pws = getpw();
 319         if (strlen(pws) < 2)
 320                 die("slock: failed to get user password hash.\n");
 321 #endif
 322
 323         if (!(dpy = XOpenDisplay(NULL)))
 324                 die("slock: cannot open display\n");
 325
 326         /* check for Xrandr support */
 327         rr = XRRQueryExtension(dpy, &rrevbase, &rrerrbase);
 328
 329         /* get number of screens in display "dpy" and blank them */
 330         nscreens = ScreenCount(dpy);
 331         if (!(locks = malloc(sizeof(Lock *) * nscreens))) {
 332                 XCloseDisplay(dpy);
 333                 die("slock: out of memory\n");
 334         }
 335         for (nlocks = 0, s = 0; s < nscreens; s++) {
 336                 if ((locks[s] = lockscreen(dpy, s)) != NULL)
 337                         nlocks++;
 338         }
 339         XSync(dpy, 0);
 340
 341         /* did we actually manage to lock anything? */
 342         if (nlocks == 0) {
 343                 /* nothing to protect */
 344                 free(locks);
 345                 XCloseDisplay(dpy);
 346                 return 1;
 347         }
 348
 349         /* run post-lock command */
 350         if (argc > 0) {
 351                 switch (fork()) {
 352                 case -1:
 353                         free(locks);
 354                         XCloseDisplay(dpy);
 355                         die("slock: fork failed: %s\n", strerror(errno));
 356                 case 0:
 357                         if (close(ConnectionNumber(dpy)) < 0)
 358                                 die("slock: close: %s\n", strerror(errno));
 359                         execvp(argv[0], argv);
 360                         fprintf(stderr, "slock: execvp %s: %s\n", argv[0],
 361                                 strerror(errno));
 362                         _exit(1);
 363                 }
 364         }
 365
 366         /* everything is now blank. Wait for the correct password */
 367 #ifdef HAVE_BSD_AUTH
 368         readpw(dpy);
 369 #else
 370         readpw(dpy, pws);
 371 #endif
 372
 373         /* password ok, unlock everything and quit */
 374         for (s = 0; s < nscreens; s++)
 375                 unlockscreen(dpy, locks[s]);
 376
 377         free(locks);
 378         XCloseDisplay(dpy);
 379
 380         return 0;
 381 }