slock.c (10352B) - raw

      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 <grp.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/extensions/Xrandr.h>
     18 #include <X11/extensions/dpms.h>
     19 #include <X11/keysym.h>
     20 #include <X11/Xlib.h>
     21 #include <X11/Xutil.h>
     22 
     23 #include "arg.h"
     24 #include "util.h"
     25 
     26 char *argv0;
     27 
     28 enum {
     29 	INIT,
     30 	INPUT,
     31 	FAILED,
     32 	NUMCOLS
     33 };
     34 
     35 struct lock {
     36 	int screen;
     37 	Window root, win;
     38 	Pixmap pmap;
     39 	unsigned long colors[NUMCOLS];
     40 };
     41 
     42 struct xrandr {
     43 	int active;
     44 	int evbase;
     45 	int errbase;
     46 };
     47 
     48 #include "config.h"
     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 #include <linux/oom.h>
     64 
     65 static void
     66 dontkillme(void)
     67 {
     68 	FILE *f;
     69 	const char oomfile[] = "/proc/self/oom_score_adj";
     70 
     71 	if (!(f = fopen(oomfile, "w"))) {
     72 		if (errno == ENOENT)
     73 			return;
     74 		die("slock: fopen %s: %s\n", oomfile, strerror(errno));
     75 	}
     76 	fprintf(f, "%d", OOM_SCORE_ADJ_MIN);
     77 	if (fclose(f)) {
     78 		if (errno == EACCES)
     79 			die("slock: unable to disable OOM killer. "
     80 			    "Make sure to suid or sgid slock.\n");
     81 		else
     82 			die("slock: fclose %s: %s\n", oomfile, strerror(errno));
     83 	}
     84 }
     85 #endif
     86 
     87 static const char *
     88 gethash(void)
     89 {
     90 	const char *hash;
     91 	struct passwd *pw;
     92 
     93 	/* Check if the current user has a password entry */
     94 	errno = 0;
     95 	if (!(pw = getpwuid(getuid()))) {
     96 		if (errno)
     97 			die("slock: getpwuid: %s\n", strerror(errno));
     98 		else
     99 			die("slock: cannot retrieve password entry\n");
    100 	}
    101 	hash = pw->pw_passwd;
    102 
    103 #if HAVE_SHADOW_H
    104 	if (!strcmp(hash, "x")) {
    105 		struct spwd *sp;
    106 		if (!(sp = getspnam(pw->pw_name)))
    107 			die("slock: getspnam: cannot retrieve shadow entry. "
    108 			    "Make sure to suid or sgid slock.\n");
    109 		hash = sp->sp_pwdp;
    110 	}
    111 #else
    112 	if (!strcmp(hash, "*")) {
    113 #ifdef __OpenBSD__
    114 		if (!(pw = getpwuid_shadow(getuid())))
    115 			die("slock: getpwnam_shadow: cannot retrieve shadow entry. "
    116 			    "Make sure to suid or sgid slock.\n");
    117 		hash = pw->pw_passwd;
    118 #else
    119 		die("slock: getpwuid: cannot retrieve shadow entry. "
    120 		    "Make sure to suid or sgid slock.\n");
    121 #endif /* __OpenBSD__ */
    122 	}
    123 #endif /* HAVE_SHADOW_H */
    124 
    125 	return hash;
    126 }
    127 
    128 static void
    129 readpw(Display *dpy, struct xrandr *rr, struct lock **locks, int nscreens,
    130        const char *hash)
    131 {
    132 	XRRScreenChangeNotifyEvent *rre;
    133 	char buf[32], passwd[256], *inputhash;
    134 	int num, screen, running, failure, oldc;
    135 	unsigned int len, color;
    136 	KeySym ksym;
    137 	XEvent ev;
    138 
    139 	len = 0;
    140 	running = 1;
    141 	failure = 0;
    142 	oldc = INIT;
    143 
    144 	while (running && !XNextEvent(dpy, &ev)) {
    145 		if (ev.type == KeyPress) {
    146 			explicit_bzero(&buf, sizeof(buf));
    147 			num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0);
    148 			if (IsKeypadKey(ksym)) {
    149 				if (ksym == XK_KP_Enter)
    150 					ksym = XK_Return;
    151 				else if (ksym >= XK_KP_0 && ksym <= XK_KP_9)
    152 					ksym = (ksym - XK_KP_0) + XK_0;
    153 			}
    154 			if (IsFunctionKey(ksym) ||
    155 			    IsKeypadKey(ksym) ||
    156 			    IsMiscFunctionKey(ksym) ||
    157 			    IsPFKey(ksym) ||
    158 			    IsPrivateKeypadKey(ksym))
    159 				continue;
    160 			switch (ksym) {
    161 			case XK_Return:
    162 				passwd[len] = '\0';
    163 				errno = 0;
    164 				if (!(inputhash = crypt(passwd, hash)))
    165 					fprintf(stderr, "slock: crypt: %s\n", strerror(errno));
    166 				else
    167 					running = !!strcmp(inputhash, hash);
    168 				if (running) {
    169 					XBell(dpy, 100);
    170 					failure = 1;
    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]) &&
    185 				    (len + num < sizeof(passwd))) {
    186 					memcpy(passwd + len, buf, num);
    187 					len += num;
    188 				}
    189 				break;
    190 			}
    191 			color = len ? INPUT : ((failure || failonclear) ? FAILED : INIT);
    192 			if (running && oldc != color) {
    193 				for (screen = 0; screen < nscreens; screen++) {
    194 					XSetWindowBackground(dpy,
    195 					                     locks[screen]->win,
    196 					                     locks[screen]->colors[color]);
    197 					XClearWindow(dpy, locks[screen]->win);
    198 				}
    199 				oldc = color;
    200 			}
    201 		} else if (rr->active && ev.type == rr->evbase + RRScreenChangeNotify) {
    202 			rre = (XRRScreenChangeNotifyEvent*)&ev;
    203 			for (screen = 0; screen < nscreens; screen++) {
    204 				if (locks[screen]->win == rre->window) {
    205 					if (rre->rotation == RR_Rotate_90 ||
    206 					    rre->rotation == RR_Rotate_270)
    207 						XResizeWindow(dpy, locks[screen]->win,
    208 						              rre->height, rre->width);
    209 					else
    210 						XResizeWindow(dpy, locks[screen]->win,
    211 						              rre->width, rre->height);
    212 					XClearWindow(dpy, locks[screen]->win);
    213 					break;
    214 				}
    215 			}
    216 		} else {
    217 			for (screen = 0; screen < nscreens; screen++)
    218 				XRaiseWindow(dpy, locks[screen]->win);
    219 		}
    220 	}
    221 }
    222 
    223 static struct lock *
    224 lockscreen(Display *dpy, struct xrandr *rr, int screen)
    225 {
    226 	char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
    227 	int i, ptgrab, kbgrab;
    228 	struct lock *lock;
    229 	XColor color, dummy;
    230 	XSetWindowAttributes wa;
    231 	Cursor invisible;
    232 
    233 	if (dpy == NULL || screen < 0 || !(lock = malloc(sizeof(struct lock))))
    234 		return NULL;
    235 
    236 	lock->screen = screen;
    237 	lock->root = RootWindow(dpy, lock->screen);
    238 
    239 	for (i = 0; i < NUMCOLS; i++) {
    240 		XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen),
    241 		                 colorname[i], &color, &dummy);
    242 		lock->colors[i] = color.pixel;
    243 	}
    244 
    245 	/* init */
    246 	wa.override_redirect = 1;
    247 	wa.background_pixel = lock->colors[INIT];
    248 	lock->win = XCreateWindow(dpy, lock->root, 0, 0,
    249 	                          DisplayWidth(dpy, lock->screen),
    250 	                          DisplayHeight(dpy, lock->screen),
    251 	                          0, DefaultDepth(dpy, lock->screen),
    252 	                          CopyFromParent,
    253 	                          DefaultVisual(dpy, lock->screen),
    254 	                          CWOverrideRedirect | CWBackPixel, &wa);
    255 	lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
    256 	invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap,
    257 	                                &color, &color, 0, 0);
    258 	XDefineCursor(dpy, lock->win, invisible);
    259 
    260 	/* Try to grab mouse pointer *and* keyboard for 600ms, else fail the lock */
    261 	for (i = 0, ptgrab = kbgrab = -1; i < 6; i++) {
    262 		if (ptgrab != GrabSuccess) {
    263 			ptgrab = XGrabPointer(dpy, lock->root, False,
    264 			                      ButtonPressMask | ButtonReleaseMask |
    265 			                      PointerMotionMask, GrabModeAsync,
    266 			                      GrabModeAsync, None, invisible, CurrentTime);
    267 		}
    268 		if (kbgrab != GrabSuccess) {
    269 			kbgrab = XGrabKeyboard(dpy, lock->root, True,
    270 			                       GrabModeAsync, GrabModeAsync, CurrentTime);
    271 		}
    272 
    273 		/* input is grabbed: we can lock the screen */
    274 		if (ptgrab == GrabSuccess && kbgrab == GrabSuccess) {
    275 			XMapRaised(dpy, lock->win);
    276 			if (rr->active)
    277 				XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
    278 
    279 			XSelectInput(dpy, lock->root, SubstructureNotifyMask);
    280 			return lock;
    281 		}
    282 
    283 		/* retry on AlreadyGrabbed but fail on other errors */
    284 		if ((ptgrab != AlreadyGrabbed && ptgrab != GrabSuccess) ||
    285 		    (kbgrab != AlreadyGrabbed && kbgrab != GrabSuccess))
    286 			break;
    287 
    288 		usleep(100000);
    289 	}
    290 
    291 	/* we couldn't grab all input: fail out */
    292 	if (ptgrab != GrabSuccess)
    293 		fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n",
    294 		        screen);
    295 	if (kbgrab != GrabSuccess)
    296 		fprintf(stderr, "slock: unable to grab keyboard for screen %d\n",
    297 		        screen);
    298 	return NULL;
    299 }
    300 
    301 static void
    302 usage(void)
    303 {
    304 	die("usage: slock [-v] [cmd [arg ...]]\n");
    305 }
    306 
    307 int
    308 main(int argc, char **argv) {
    309 	struct xrandr rr;
    310 	struct lock **locks;
    311 	struct passwd *pwd;
    312 	struct group *grp;
    313 	uid_t duid;
    314 	gid_t dgid;
    315 	const char *hash;
    316 	Display *dpy;
    317 	int s, nlocks, nscreens;
    318 	CARD16 standby, suspend, off;
    319 
    320 	ARGBEGIN {
    321 	case 'v':
    322 		fprintf(stderr, "slock-"VERSION"\n");
    323 		return 0;
    324 	default:
    325 		usage();
    326 	} ARGEND
    327 
    328 	/* validate drop-user and -group */
    329 	errno = 0;
    330 	if (!(pwd = getpwnam(user)))
    331 		die("slock: getpwnam %s: %s\n", user,
    332 		    errno ? strerror(errno) : "user entry not found");
    333 	duid = pwd->pw_uid;
    334 	errno = 0;
    335 	if (!(grp = getgrnam(group)))
    336 		die("slock: getgrnam %s: %s\n", group,
    337 		    errno ? strerror(errno) : "group entry not found");
    338 	dgid = grp->gr_gid;
    339 
    340 #ifdef __linux__
    341 	dontkillme();
    342 #endif
    343 
    344 	hash = gethash();
    345 	errno = 0;
    346 	if (!crypt("", hash))
    347 		die("slock: crypt: %s\n", strerror(errno));
    348 
    349 	if (!(dpy = XOpenDisplay(NULL)))
    350 		die("slock: cannot open display\n");
    351 
    352 	/* drop privileges */
    353 	if (setgroups(0, NULL) < 0)
    354 		die("slock: setgroups: %s\n", strerror(errno));
    355 	if (setgid(dgid) < 0)
    356 		die("slock: setgid: %s\n", strerror(errno));
    357 	if (setuid(duid) < 0)
    358 		die("slock: setuid: %s\n", strerror(errno));
    359 
    360 	/* check for Xrandr support */
    361 	rr.active = XRRQueryExtension(dpy, &rr.evbase, &rr.errbase);
    362 
    363 	/* get number of screens in display "dpy" and blank them */
    364 	nscreens = ScreenCount(dpy);
    365 	if (!(locks = calloc(nscreens, sizeof(struct lock *))))
    366 		die("slock: out of memory\n");
    367 	for (nlocks = 0, s = 0; s < nscreens; s++) {
    368 		if ((locks[s] = lockscreen(dpy, &rr, s)) != NULL)
    369 			nlocks++;
    370 		else
    371 			break;
    372 	}
    373 	XSync(dpy, 0);
    374 
    375 	/* did we manage to lock everything? */
    376 	if (nlocks != nscreens)
    377 		return 1;
    378 
    379 	/* DPMS magic to disable the monitor */
    380 	if (!DPMSCapable(dpy))
    381 		die("slock: DPMSCapable failed\n");
    382 	if (!DPMSEnable(dpy))
    383 		die("slock: DPMSEnable failed\n");
    384 	if (!DPMSGetTimeouts(dpy, &standby, &suspend, &off))
    385 		die("slock: DPMSGetTimeouts failed\n");
    386 	if (!standby || !suspend || !off)
    387 		die("slock: at least one DPMS variable is zero\n");
    388 	if (!DPMSSetTimeouts(dpy, monitortime, monitortime, monitortime))
    389 		die("slock: DPMSSetTimeouts failed\n");
    390 
    391 	XSync(dpy, 0);
    392 
    393 	/* run post-lock command */
    394 	if (argc > 0) {
    395 		switch (fork()) {
    396 		case -1:
    397 			die("slock: fork failed: %s\n", strerror(errno));
    398 		case 0:
    399 			if (close(ConnectionNumber(dpy)) < 0)
    400 				die("slock: close: %s\n", strerror(errno));
    401 			execvp(argv[0], argv);
    402 			fprintf(stderr, "slock: execvp %s: %s\n", argv[0], strerror(errno));
    403 			_exit(1);
    404 		}
    405 	}
    406 
    407 	/* everything is now blank. Wait for the correct password */
    408 	readpw(dpy, &rr, locks, nscreens, hash);
    409 
    410 	/* reset DPMS values to inital ones */
    411 	DPMSSetTimeouts(dpy, standby, suspend, off);
    412 	XSync(dpy, 0);
    413 
    414 	return 0;
    415 }