slock.c (9695B)
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/keysym.h> 19 #include <X11/Xlib.h> 20 #include <X11/Xutil.h> 21 22 #include "arg.h" 23 #include "util.h" 24 25 char *argv0; 26 27 enum { 28 INIT, 29 INPUT, 30 FAILED, 31 NUMCOLS 32 }; 33 34 struct lock { 35 int screen; 36 Window root, win; 37 Pixmap pmap; 38 unsigned long colors[NUMCOLS]; 39 }; 40 41 struct xrandr { 42 int active; 43 int evbase; 44 int errbase; 45 }; 46 47 #include "config.h" 48 49 static void 50 die(const char *errstr, ...) 51 { 52 va_list ap; 53 54 va_start(ap, errstr); 55 vfprintf(stderr, errstr, ap); 56 va_end(ap); 57 exit(1); 58 } 59 60 #ifdef __linux__ 61 #include <fcntl.h> 62 #include <linux/oom.h> 63 64 static void 65 dontkillme(void) 66 { 67 FILE *f; 68 const char oomfile[] = "/proc/self/oom_score_adj"; 69 70 if (!(f = fopen(oomfile, "w"))) { 71 if (errno == ENOENT) 72 return; 73 die("slock: fopen %s: %s\n", oomfile, strerror(errno)); 74 } 75 fprintf(f, "%d", OOM_SCORE_ADJ_MIN); 76 if (fclose(f)) { 77 if (errno == EACCES) 78 die("slock: unable to disable OOM killer. " 79 "Make sure to suid or sgid slock.\n"); 80 else 81 die("slock: fclose %s: %s\n", oomfile, strerror(errno)); 82 } 83 } 84 #endif 85 86 static const char * 87 gethash(void) 88 { 89 const char *hash; 90 struct passwd *pw; 91 92 /* Check if the current user has a password entry */ 93 errno = 0; 94 if (!(pw = getpwuid(getuid()))) { 95 if (errno) 96 die("slock: getpwuid: %s\n", strerror(errno)); 97 else 98 die("slock: cannot retrieve password entry\n"); 99 } 100 hash = pw->pw_passwd; 101 102 #if HAVE_SHADOW_H 103 if (!strcmp(hash, "x")) { 104 struct spwd *sp; 105 if (!(sp = getspnam(pw->pw_name))) 106 die("slock: getspnam: cannot retrieve shadow entry. " 107 "Make sure to suid or sgid slock.\n"); 108 hash = sp->sp_pwdp; 109 } 110 #else 111 if (!strcmp(hash, "*")) { 112 #ifdef __OpenBSD__ 113 if (!(pw = getpwuid_shadow(getuid()))) 114 die("slock: getpwnam_shadow: cannot retrieve shadow entry. " 115 "Make sure to suid or sgid slock.\n"); 116 hash = pw->pw_passwd; 117 #else 118 die("slock: getpwuid: cannot retrieve shadow entry. " 119 "Make sure to suid or sgid slock.\n"); 120 #endif /* __OpenBSD__ */ 121 } 122 #endif /* HAVE_SHADOW_H */ 123 124 return hash; 125 } 126 127 static void 128 readpw(Display *dpy, struct xrandr *rr, struct lock **locks, int nscreens, 129 const char *hash) 130 { 131 XRRScreenChangeNotifyEvent *rre; 132 char buf[32], passwd[256], *inputhash; 133 int num, screen, running, failure, oldc; 134 unsigned int len, color; 135 KeySym ksym; 136 XEvent ev; 137 138 len = 0; 139 running = 1; 140 failure = 0; 141 oldc = INIT; 142 143 while (running && !XNextEvent(dpy, &ev)) { 144 if (ev.type == KeyPress) { 145 explicit_bzero(&buf, sizeof(buf)); 146 num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0); 147 if (IsKeypadKey(ksym)) { 148 if (ksym == XK_KP_Enter) 149 ksym = XK_Return; 150 else if (ksym >= XK_KP_0 && ksym <= XK_KP_9) 151 ksym = (ksym - XK_KP_0) + XK_0; 152 } 153 if (IsFunctionKey(ksym) || 154 IsKeypadKey(ksym) || 155 IsMiscFunctionKey(ksym) || 156 IsPFKey(ksym) || 157 IsPrivateKeypadKey(ksym)) 158 continue; 159 switch (ksym) { 160 case XK_Return: 161 passwd[len] = '\0'; 162 errno = 0; 163 if (!(inputhash = crypt(passwd, hash))) 164 fprintf(stderr, "slock: crypt: %s\n", strerror(errno)); 165 else 166 running = !!strcmp(inputhash, hash); 167 if (running) { 168 XBell(dpy, 100); 169 failure = 1; 170 } 171 explicit_bzero(&passwd, sizeof(passwd)); 172 len = 0; 173 break; 174 case XK_Escape: 175 explicit_bzero(&passwd, sizeof(passwd)); 176 len = 0; 177 break; 178 case XK_BackSpace: 179 if (len) 180 passwd[--len] = '\0'; 181 break; 182 default: 183 if (num && !iscntrl((int)buf[0]) && 184 (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, 194 locks[screen]->win, 195 locks[screen]->colors[color]); 196 XClearWindow(dpy, locks[screen]->win); 197 } 198 oldc = color; 199 } 200 } else if (rr->active && ev.type == rr->evbase + RRScreenChangeNotify) { 201 rre = (XRRScreenChangeNotifyEvent*)&ev; 202 for (screen = 0; screen < nscreens; screen++) { 203 if (locks[screen]->win == rre->window) { 204 if (rre->rotation == RR_Rotate_90 || 205 rre->rotation == RR_Rotate_270) 206 XResizeWindow(dpy, locks[screen]->win, 207 rre->height, rre->width); 208 else 209 XResizeWindow(dpy, locks[screen]->win, 210 rre->width, rre->height); 211 XClearWindow(dpy, locks[screen]->win); 212 break; 213 } 214 } 215 } else { 216 for (screen = 0; screen < nscreens; screen++) 217 XRaiseWindow(dpy, locks[screen]->win); 218 } 219 } 220 } 221 222 static struct lock * 223 lockscreen(Display *dpy, struct xrandr *rr, int screen) 224 { 225 char curs[] = {0, 0, 0, 0, 0, 0, 0, 0}; 226 int i, ptgrab, kbgrab; 227 struct lock *lock; 228 XColor color, dummy; 229 XSetWindowAttributes wa; 230 Cursor invisible; 231 232 if (dpy == NULL || screen < 0 || !(lock = malloc(sizeof(struct lock)))) 233 return NULL; 234 235 lock->screen = screen; 236 lock->root = RootWindow(dpy, lock->screen); 237 238 for (i = 0; i < NUMCOLS; i++) { 239 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), 240 colorname[i], &color, &dummy); 241 lock->colors[i] = color.pixel; 242 } 243 244 /* init */ 245 wa.override_redirect = 1; 246 wa.background_pixel = lock->colors[INIT]; 247 lock->win = XCreateWindow(dpy, lock->root, 0, 0, 248 DisplayWidth(dpy, lock->screen), 249 DisplayHeight(dpy, lock->screen), 250 0, DefaultDepth(dpy, lock->screen), 251 CopyFromParent, 252 DefaultVisual(dpy, lock->screen), 253 CWOverrideRedirect | CWBackPixel, &wa); 254 lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8); 255 invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, 256 &color, &color, 0, 0); 257 XDefineCursor(dpy, lock->win, invisible); 258 259 /* Try to grab mouse pointer *and* keyboard for 600ms, else fail the lock */ 260 for (i = 0, ptgrab = kbgrab = -1; i < 6; i++) { 261 if (ptgrab != GrabSuccess) { 262 ptgrab = XGrabPointer(dpy, lock->root, False, 263 ButtonPressMask | ButtonReleaseMask | 264 PointerMotionMask, GrabModeAsync, 265 GrabModeAsync, None, invisible, CurrentTime); 266 } 267 if (kbgrab != GrabSuccess) { 268 kbgrab = XGrabKeyboard(dpy, lock->root, True, 269 GrabModeAsync, GrabModeAsync, CurrentTime); 270 } 271 272 /* input is grabbed: we can lock the screen */ 273 if (ptgrab == GrabSuccess && kbgrab == GrabSuccess) { 274 XMapRaised(dpy, lock->win); 275 if (rr->active) 276 XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask); 277 278 XSelectInput(dpy, lock->root, SubstructureNotifyMask); 279 return lock; 280 } 281 282 /* retry on AlreadyGrabbed but fail on other errors */ 283 if ((ptgrab != AlreadyGrabbed && ptgrab != GrabSuccess) || 284 (kbgrab != AlreadyGrabbed && kbgrab != GrabSuccess)) 285 break; 286 287 usleep(100000); 288 } 289 290 /* we couldn't grab all input: fail out */ 291 if (ptgrab != GrabSuccess) 292 fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n", 293 screen); 294 if (kbgrab != GrabSuccess) 295 fprintf(stderr, "slock: unable to grab keyboard for screen %d\n", 296 screen); 297 return NULL; 298 } 299 300 static void 301 usage(void) 302 { 303 die("usage: slock [-v] [cmd [arg ...]]\n"); 304 } 305 306 int 307 main(int argc, char **argv) { 308 struct xrandr rr; 309 struct lock **locks; 310 struct passwd *pwd; 311 struct group *grp; 312 uid_t duid; 313 gid_t dgid; 314 const char *hash; 315 Display *dpy; 316 int s, nlocks, nscreens; 317 318 ARGBEGIN { 319 case 'v': 320 puts("slock-"VERSION); 321 return 0; 322 default: 323 usage(); 324 } ARGEND 325 326 /* validate drop-user and -group */ 327 errno = 0; 328 if (!(pwd = getpwnam(user))) 329 die("slock: getpwnam %s: %s\n", user, 330 errno ? strerror(errno) : "user entry not found"); 331 duid = pwd->pw_uid; 332 errno = 0; 333 if (!(grp = getgrnam(group))) 334 die("slock: getgrnam %s: %s\n", group, 335 errno ? strerror(errno) : "group entry not found"); 336 dgid = grp->gr_gid; 337 338 #ifdef __linux__ 339 dontkillme(); 340 #endif 341 342 hash = gethash(); 343 errno = 0; 344 if (!crypt("", hash)) 345 die("slock: crypt: %s\n", strerror(errno)); 346 347 if (!(dpy = XOpenDisplay(NULL))) 348 die("slock: cannot open display\n"); 349 350 /* drop privileges */ 351 if (setgroups(0, NULL) < 0) 352 die("slock: setgroups: %s\n", strerror(errno)); 353 if (setgid(dgid) < 0) 354 die("slock: setgid: %s\n", strerror(errno)); 355 if (setuid(duid) < 0) 356 die("slock: setuid: %s\n", strerror(errno)); 357 358 /* check for Xrandr support */ 359 rr.active = XRRQueryExtension(dpy, &rr.evbase, &rr.errbase); 360 361 /* get number of screens in display "dpy" and blank them */ 362 nscreens = ScreenCount(dpy); 363 if (!(locks = calloc(nscreens, sizeof(struct lock *)))) 364 die("slock: out of memory\n"); 365 for (nlocks = 0, s = 0; s < nscreens; s++) { 366 if ((locks[s] = lockscreen(dpy, &rr, s)) != NULL) 367 nlocks++; 368 else 369 break; 370 } 371 XSync(dpy, 0); 372 373 /* did we manage to lock everything? */ 374 if (nlocks != nscreens) 375 return 1; 376 377 /* run post-lock command */ 378 if (argc > 0) { 379 switch (fork()) { 380 case -1: 381 die("slock: fork failed: %s\n", strerror(errno)); 382 case 0: 383 if (close(ConnectionNumber(dpy)) < 0) 384 die("slock: close: %s\n", strerror(errno)); 385 execvp(argv[0], argv); 386 fprintf(stderr, "slock: execvp %s: %s\n", argv[0], strerror(errno)); 387 _exit(1); 388 } 389 } 390 391 /* everything is now blank. Wait for the correct password */ 392 readpw(dpy, &rr, locks, nscreens, hash); 393 394 return 0; 395 }