summaryrefslogtreecommitdiff
path: root/slock.c
blob: dd323740bbdd0206cbc9685031360ba2fe0ea7c4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
/* See LICENSE file for license details. */
#define _XOPEN_SOURCE 500
#if HAVE_SHADOW_H
#include <shadow.h>
#endif

#include <ctype.h>
#include <errno.h>
#include <pwd.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <X11/extensions/Xrandr.h>
#include <X11/keysym.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>

#if HAVE_BSD_AUTH
#include <login_cap.h>
#include <bsd_auth.h>
#endif

#include "arg.h"
#include "util.h"

char *argv0;

enum {
	INIT,
	INPUT,
	FAILED,
	NUMCOLS
};

#include "config.h"

typedef struct {
	int screen;
	Window root, win;
	Pixmap pmap;
	unsigned long colors[NUMCOLS];
} Lock;

static Lock **locks;
static int nscreens;
static Bool running = True;
static Bool failure = False;
static Bool rr;
static int rrevbase;
static int rrerrbase;

static void
die(const char *errstr, ...)
{
	va_list ap;

	va_start(ap, errstr);
	vfprintf(stderr, errstr, ap);
	va_end(ap);
	exit(1);
}

#ifdef __linux__
#include <fcntl.h>

static void
dontkillme(void)
{
	int fd;

	fd = open("/proc/self/oom_score_adj", O_WRONLY);
	if (fd < 0 && errno == ENOENT) {
		return;
	}
	if (fd < 0 || write(fd, "-1000\n", (sizeof("-1000\n") - 1)) !=
	    (sizeof("-1000\n") - 1) || close(fd) != 0) {
		die("can't tame the oom-killer. is suid or sgid set?\n");
	}
}
#endif

#ifndef HAVE_BSD_AUTH
/* only run as root */
static const char *
getpw(void)
{
	const char *rval;
	struct passwd *pw;

	errno = 0;
	if (!(pw = getpwuid(getuid()))) {
		if (errno)
			die("getpwuid: %s\n", strerror(errno));
		else
			die("cannot retrieve password entry\n");
	}
	rval = pw->pw_passwd;

#if HAVE_SHADOW_H
	if (rval[0] == 'x' && rval[1] == '\0') {
		struct spwd *sp;
		if (!(sp = getspnam(getenv("USER"))))
			die("cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
		rval = sp->sp_pwdp;
	}
#endif

	/* drop privileges */
	if (geteuid() == 0 &&
	    ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
		die("cannot drop privileges\n");
	return rval;
}
#endif

static void
#ifdef HAVE_BSD_AUTH
readpw(Display *dpy)
#else
readpw(Display *dpy, const char *pws)
#endif
{
	char buf[32], passwd[256];
	int num, screen;
	unsigned int len, color;
	KeySym ksym;
	XEvent ev;
	static int oldc = INIT;

	len = 0;
	running = True;

	/* As "slock" stands for "Simple X display locker", the DPMS settings
	 * had been removed and you can set it with "xset" or some other
	 * utility. This way the user can easily set a customized DPMS
	 * timeout. */
	while (running && !XNextEvent(dpy, &ev)) {
		if (ev.type == KeyPress) {
			explicit_bzero(&buf, sizeof(buf));
			num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0);
			if (IsKeypadKey(ksym)) {
				if (ksym == XK_KP_Enter)
					ksym = XK_Return;
				else if (ksym >= XK_KP_0 && ksym <= XK_KP_9)
					ksym = (ksym - XK_KP_0) + XK_0;
			}
			if (IsFunctionKey(ksym) ||
			    IsKeypadKey(ksym) ||
			    IsMiscFunctionKey(ksym) ||
			    IsPFKey(ksym) ||
			    IsPrivateKeypadKey(ksym))
				continue;
			switch (ksym) {
			case XK_Return:
				passwd[len] = 0;
#ifdef HAVE_BSD_AUTH
				running = !auth_userokay(getlogin(), NULL, "auth-xlock", passwd);
#else
				running = !!strcmp(crypt(passwd, pws), pws);
#endif
				if (running) {
					XBell(dpy, 100);
					failure = True;
				}
				explicit_bzero(&passwd, sizeof(passwd));
				len = 0;
				break;
			case XK_Escape:
				explicit_bzero(&passwd, sizeof(passwd));
				len = 0;
				break;
			case XK_BackSpace:
				if (len)
					passwd[len--] = 0;
				break;
			default:
				if (num && !iscntrl((int)buf[0]) && (len + num < sizeof(passwd))) {
					memcpy(passwd + len, buf, num);
					len += num;
				}
				break;
			}
			color = len ? INPUT : (failure || failonclear ? FAILED : INIT);
			if (running && oldc != color) {
				for (screen = 0; screen < nscreens; screen++) {
					XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[color]);
					XClearWindow(dpy, locks[screen]->win);
				}
				oldc = color;
			}
		} else if (rr && ev.type == rrevbase + RRScreenChangeNotify) {
			XRRScreenChangeNotifyEvent *rre = (XRRScreenChangeNotifyEvent*)&ev;
			for (screen = 0; screen < nscreens; screen++) {
				if (locks[screen]->win == rre->window) {
					XResizeWindow(dpy, locks[screen]->win, rre->width, rre->height);
					XClearWindow(dpy, locks[screen]->win);
				}
			}
		} else for (screen = 0; screen < nscreens; screen++)
			XRaiseWindow(dpy, locks[screen]->win);
	}
}

static void
unlockscreen(Display *dpy, Lock *lock)
{
	if(dpy == NULL || lock == NULL)
		return;

	XUngrabPointer(dpy, CurrentTime);
	XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, NUMCOLS, 0);
	XFreePixmap(dpy, lock->pmap);
	XDestroyWindow(dpy, lock->win);

	free(lock);
}

static Lock *
lockscreen(Display *dpy, int screen)
{
	char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
	int i;
	Lock *lock;
	XColor color, dummy;
	XSetWindowAttributes wa;
	Cursor invisible;

	if (!running || dpy == NULL || screen < 0 || !(lock = malloc(sizeof(Lock))))
		return NULL;

	lock->screen = screen;
	lock->root = RootWindow(dpy, lock->screen);

	for (i = 0; i < NUMCOLS; i++) {
		XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), colorname[i], &color, &dummy);
		lock->colors[i] = color.pixel;
	}

	/* init */
	wa.override_redirect = 1;
	wa.background_pixel = lock->colors[INIT];
	lock->win = XCreateWindow(dpy, lock->root, 0, 0, DisplayWidth(dpy, lock->screen), DisplayHeight(dpy, lock->screen),
	                          0, DefaultDepth(dpy, lock->screen), CopyFromParent,
	                          DefaultVisual(dpy, lock->screen), CWOverrideRedirect | CWBackPixel, &wa);
	lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
	invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
	XDefineCursor(dpy, lock->win, invisible);

	/* Try to grab mouse pointer *and* keyboard, else fail the lock */
	if (XGrabPointer(dpy, lock->root, False, ButtonPressMask |
	    ButtonReleaseMask | PointerMotionMask, GrabModeAsync, GrabModeAsync,
	    None, invisible, CurrentTime) != GrabSuccess) {
		fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n", screen);
		running = 0;
		unlockscreen(dpy, lock);
		return NULL;
	}

	if (XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync,
	    CurrentTime) != GrabSuccess) {
		fprintf(stderr, "slock: unable to grab keyboard for screen %d\n", screen);
		running = 0;
		unlockscreen(dpy, lock);
		return NULL;
	}

	XMapRaised(dpy, lock->win);
	if (rr)
		XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);

	XSelectInput(dpy, lock->root, SubstructureNotifyMask);
	return lock;
}

static void
usage(void)
{
	die("usage: slock [-v | cmd [arg ...]]\n");
}

int
main(int argc, char **argv) {
#ifndef HAVE_BSD_AUTH
	const char *pws;
#endif
	Display *dpy;
	int s, nlocks;

	ARGBEGIN {
	case 'v':
		fprintf(stderr, "slock-"VERSION"\n");
		return 0;
	default:
		usage();
	} ARGEND

#ifdef __linux__
	dontkillme();
#endif

	/* Check if the current user has a password entry */
	errno = 0;
	if (!getpwuid(getuid())) {
		if (errno == 0)
			die("slock: no password entry for current user\n");
		else
			die("slock: getpwuid: %s\n", strerror(errno));
	}

#ifndef HAVE_BSD_AUTH
	pws = getpw();
#endif

	if (!(dpy = XOpenDisplay(NULL)))
		die("slock: cannot open display\n");

	/* check for Xrandr support */
	rr = XRRQueryExtension(dpy, &rrevbase, &rrerrbase);

	/* get number of screens in display "dpy" and blank them */
	nscreens = ScreenCount(dpy);
	if (!(locks = malloc(sizeof(Lock *) * nscreens))) {
		XCloseDisplay(dpy);
		die("slock: out of memory\n");
	}
	for (nlocks = 0, s = 0; s < nscreens; s++) {
		if ((locks[s] = lockscreen(dpy, s)) != NULL)
			nlocks++;
	}
	XSync(dpy, 0);

	/* did we actually manage to lock anything? */
	if (nlocks == 0) {
		/* nothing to protect */
		free(locks);
		XCloseDisplay(dpy);
		return 1;
	}

	/* run post-lock command */
	if (argc > 0) {
		switch (fork()) {
		case -1:
			free(locks);
			XCloseDisplay(dpy);
			die("slock: fork failed: %s\n", strerror(errno));
		case 0:
			if (close(ConnectionNumber(dpy)) < 0)
				die("slock: close: %s\n", strerror(errno));
			execvp(argv[0], argv);
			fprintf(stderr, "slock: execvp %s: %s\n", argv[0],
			        strerror(errno));
			_exit(1);
		}
	}

	/* everything is now blank. Wait for the correct password */
#ifdef HAVE_BSD_AUTH
	readpw(dpy);
#else
	readpw(dpy, pws);
#endif

	/* password ok, unlock everything and quit */
	for (s = 0; s < nscreens; s++)
		unlockscreen(dpy, locks[s]);

	free(locks);
	XCloseDisplay(dpy);

	return 0;
}