slock.c (9755B)
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 <spawn.h> 17 #include <sys/types.h> 18 #include <X11/extensions/Xrandr.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 } else if (buf[0] == '\025') { /* ctrl-u clears input */ 189 explicit_bzero(&passwd, sizeof(passwd)); 190 len = 0; 191 } 192 break; 193 } 194 color = len ? INPUT : ((failure || failonclear) ? FAILED : INIT); 195 if (running && oldc != color) { 196 for (screen = 0; screen < nscreens; screen++) { 197 XSetWindowBackground(dpy, 198 locks[screen]->win, 199 locks[screen]->colors[color]); 200 XClearWindow(dpy, locks[screen]->win); 201 } 202 oldc = color; 203 } 204 } else if (rr->active && ev.type == rr->evbase + RRScreenChangeNotify) { 205 rre = (XRRScreenChangeNotifyEvent*)&ev; 206 for (screen = 0; screen < nscreens; screen++) { 207 if (locks[screen]->win == rre->window) { 208 if (rre->rotation == RR_Rotate_90 || 209 rre->rotation == RR_Rotate_270) 210 XResizeWindow(dpy, locks[screen]->win, 211 rre->height, rre->width); 212 else 213 XResizeWindow(dpy, locks[screen]->win, 214 rre->width, rre->height); 215 XClearWindow(dpy, locks[screen]->win); 216 break; 217 } 218 } 219 } else { 220 for (screen = 0; screen < nscreens; screen++) 221 XRaiseWindow(dpy, locks[screen]->win); 222 } 223 } 224 } 225 226 static struct lock * 227 lockscreen(Display *dpy, struct xrandr *rr, int screen) 228 { 229 char curs[] = {0, 0, 0, 0, 0, 0, 0, 0}; 230 int i, ptgrab, kbgrab; 231 struct lock *lock; 232 XColor color, dummy; 233 XSetWindowAttributes wa; 234 Cursor invisible; 235 236 if (dpy == NULL || screen < 0 || !(lock = malloc(sizeof(struct lock)))) 237 return NULL; 238 239 lock->screen = screen; 240 lock->root = RootWindow(dpy, lock->screen); 241 242 for (i = 0; i < NUMCOLS; i++) { 243 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), 244 colorname[i], &color, &dummy); 245 lock->colors[i] = color.pixel; 246 } 247 248 /* init */ 249 wa.override_redirect = 1; 250 wa.background_pixel = lock->colors[INIT]; 251 lock->win = XCreateWindow(dpy, lock->root, 0, 0, 252 DisplayWidth(dpy, lock->screen), 253 DisplayHeight(dpy, lock->screen), 254 0, DefaultDepth(dpy, lock->screen), 255 CopyFromParent, 256 DefaultVisual(dpy, lock->screen), 257 CWOverrideRedirect | CWBackPixel, &wa); 258 lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8); 259 invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, 260 &color, &color, 0, 0); 261 XDefineCursor(dpy, lock->win, invisible); 262 263 /* Try to grab mouse pointer *and* keyboard for 600ms, else fail the lock */ 264 for (i = 0, ptgrab = kbgrab = -1; i < 6; i++) { 265 if (ptgrab != GrabSuccess) { 266 ptgrab = XGrabPointer(dpy, lock->root, False, 267 ButtonPressMask | ButtonReleaseMask | 268 PointerMotionMask, GrabModeAsync, 269 GrabModeAsync, None, invisible, CurrentTime); 270 } 271 if (kbgrab != GrabSuccess) { 272 kbgrab = XGrabKeyboard(dpy, lock->root, True, 273 GrabModeAsync, GrabModeAsync, CurrentTime); 274 } 275 276 /* input is grabbed: we can lock the screen */ 277 if (ptgrab == GrabSuccess && kbgrab == GrabSuccess) { 278 XMapRaised(dpy, lock->win); 279 if (rr->active) 280 XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask); 281 282 XSelectInput(dpy, lock->root, SubstructureNotifyMask); 283 return lock; 284 } 285 286 /* retry on AlreadyGrabbed but fail on other errors */ 287 if ((ptgrab != AlreadyGrabbed && ptgrab != GrabSuccess) || 288 (kbgrab != AlreadyGrabbed && kbgrab != GrabSuccess)) 289 break; 290 291 usleep(100000); 292 } 293 294 /* we couldn't grab all input: fail out */ 295 if (ptgrab != GrabSuccess) 296 fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n", 297 screen); 298 if (kbgrab != GrabSuccess) 299 fprintf(stderr, "slock: unable to grab keyboard for screen %d\n", 300 screen); 301 return NULL; 302 } 303 304 static void 305 usage(void) 306 { 307 die("usage: slock [-v] [cmd [arg ...]]\n"); 308 } 309 310 int 311 main(int argc, char **argv) { 312 struct xrandr rr; 313 struct lock **locks; 314 struct passwd *pwd; 315 struct group *grp; 316 uid_t duid; 317 gid_t dgid; 318 const char *hash; 319 Display *dpy; 320 int s, nlocks, nscreens; 321 322 ARGBEGIN { 323 case 'v': 324 puts("slock-"VERSION); 325 return 0; 326 default: 327 usage(); 328 } ARGEND 329 330 /* validate drop-user and -group */ 331 errno = 0; 332 if (!(pwd = getpwnam(user))) 333 die("slock: getpwnam %s: %s\n", user, 334 errno ? strerror(errno) : "user entry not found"); 335 duid = pwd->pw_uid; 336 errno = 0; 337 if (!(grp = getgrnam(group))) 338 die("slock: getgrnam %s: %s\n", group, 339 errno ? strerror(errno) : "group entry not found"); 340 dgid = grp->gr_gid; 341 342 #ifdef __linux__ 343 dontkillme(); 344 #endif 345 346 hash = gethash(); 347 errno = 0; 348 if (!crypt("", hash)) 349 die("slock: crypt: %s\n", strerror(errno)); 350 351 if (!(dpy = XOpenDisplay(NULL))) 352 die("slock: cannot open display\n"); 353 354 /* drop privileges */ 355 if (setgroups(0, NULL) < 0) 356 die("slock: setgroups: %s\n", strerror(errno)); 357 if (setgid(dgid) < 0) 358 die("slock: setgid: %s\n", strerror(errno)); 359 if (setuid(duid) < 0) 360 die("slock: setuid: %s\n", strerror(errno)); 361 362 /* check for Xrandr support */ 363 rr.active = XRRQueryExtension(dpy, &rr.evbase, &rr.errbase); 364 365 /* get number of screens in display "dpy" and blank them */ 366 nscreens = ScreenCount(dpy); 367 if (!(locks = calloc(nscreens, sizeof(struct lock *)))) 368 die("slock: out of memory\n"); 369 for (nlocks = 0, s = 0; s < nscreens; s++) { 370 if ((locks[s] = lockscreen(dpy, &rr, s)) != NULL) 371 nlocks++; 372 else 373 break; 374 } 375 XSync(dpy, 0); 376 377 /* did we manage to lock everything? */ 378 if (nlocks != nscreens) 379 return 1; 380 381 /* run post-lock command */ 382 if (argc > 0) { 383 pid_t pid; 384 extern char **environ; 385 int err = posix_spawnp(&pid, argv[0], NULL, NULL, argv, environ); 386 if (err) { 387 die("slock: failed to execute post-lock command: %s: %s\n", 388 argv[0], strerror(err)); 389 } 390 } 391 392 /* everything is now blank. Wait for the correct password */ 393 readpw(dpy, &rr, locks, nscreens, hash); 394 395 return 0; 396 }