slock.c (9472B)
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 "util.h" 23 24 char *argv0; 25 26 enum { 27 INIT, 28 INPUT, 29 FAILED, 30 NUMCOLS 31 }; 32 33 struct lock { 34 int screen; 35 Window root, win; 36 Pixmap pmap; 37 unsigned long colors[NUMCOLS]; 38 }; 39 40 struct xrandr { 41 int active; 42 int evbase; 43 int errbase; 44 }; 45 46 #include "config.h" 47 48 static void 49 die(const char *errstr, ...) 50 { 51 va_list ap; 52 53 va_start(ap, errstr); 54 vfprintf(stderr, errstr, ap); 55 va_end(ap); 56 exit(1); 57 } 58 59 #ifdef __linux__ 60 #include <fcntl.h> 61 #include <linux/oom.h> 62 63 static void 64 dontkillme(void) 65 { 66 FILE *f; 67 const char oomfile[] = "/proc/self/oom_score_adj"; 68 69 if (!(f = fopen(oomfile, "w"))) { 70 if (errno == ENOENT) 71 return; 72 die("slock: fopen %s: %s\n", oomfile, strerror(errno)); 73 } 74 fprintf(f, "%d", OOM_SCORE_ADJ_MIN); 75 if (fclose(f)) { 76 if (errno == EACCES) 77 die("slock: unable to disable OOM killer. " 78 "Make sure to suid or sgid slock.\n"); 79 else 80 die("slock: fclose %s: %s\n", oomfile, strerror(errno)); 81 } 82 } 83 #endif 84 85 static const char * 86 gethash(void) 87 { 88 const char *hash; 89 struct passwd *pw; 90 91 /* Check if the current user has a password entry */ 92 errno = 0; 93 if (!(pw = getpwuid(getuid()))) { 94 if (errno) 95 die("slock: getpwuid: %s\n", strerror(errno)); 96 else 97 die("slock: cannot retrieve password entry\n"); 98 } 99 hash = pw->pw_passwd; 100 101 #if HAVE_SHADOW_H 102 if (!strcmp(hash, "x")) { 103 struct spwd *sp; 104 if (!(sp = getspnam(pw->pw_name))) 105 die("slock: getspnam: cannot retrieve shadow entry. " 106 "Make sure to suid or sgid slock.\n"); 107 hash = sp->sp_pwdp; 108 } 109 #else 110 if (!strcmp(hash, "*")) { 111 #ifdef __OpenBSD__ 112 if (!(pw = getpwuid_shadow(getuid()))) 113 die("slock: getpwnam_shadow: cannot retrieve shadow entry. " 114 "Make sure to suid or sgid slock.\n"); 115 hash = pw->pw_passwd; 116 #else 117 die("slock: getpwuid: cannot retrieve shadow entry. " 118 "Make sure to suid or sgid slock.\n"); 119 #endif /* __OpenBSD__ */ 120 } 121 #endif /* HAVE_SHADOW_H */ 122 123 return hash; 124 } 125 126 static void 127 readpw(Display *dpy, struct xrandr *rr, struct lock **locks, int nscreens, 128 const char *hash) 129 { 130 XRRScreenChangeNotifyEvent *rre; 131 char buf[32], passwd[256], *inputhash; 132 int num, screen, running, failure, oldc; 133 unsigned int len, color; 134 KeySym ksym; 135 XEvent ev; 136 137 len = 0; 138 running = 1; 139 failure = 0; 140 oldc = INIT; 141 142 while (running && !XNextEvent(dpy, &ev)) { 143 if (ev.type == KeyPress) { 144 explicit_bzero(&buf, sizeof(buf)); 145 num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0); 146 if (IsKeypadKey(ksym)) { 147 if (ksym == XK_KP_Enter) 148 ksym = XK_Return; 149 else if (ksym >= XK_KP_0 && ksym <= XK_KP_9) 150 ksym = (ksym - XK_KP_0) + XK_0; 151 } 152 if (IsFunctionKey(ksym) || 153 IsKeypadKey(ksym) || 154 IsMiscFunctionKey(ksym) || 155 IsPFKey(ksym) || 156 IsPrivateKeypadKey(ksym)) 157 continue; 158 switch (ksym) { 159 case XK_Return: 160 passwd[len] = '\0'; 161 errno = 0; 162 if (!(inputhash = crypt(passwd, hash))) 163 fprintf(stderr, "slock: crypt: %s\n", strerror(errno)); 164 else 165 running = !!strcmp(inputhash, hash); 166 if (running) { 167 XBell(dpy, 100); 168 failure = 1; 169 } 170 explicit_bzero(&passwd, sizeof(passwd)); 171 len = 0; 172 break; 173 case XK_Escape: 174 explicit_bzero(&passwd, sizeof(passwd)); 175 len = 0; 176 break; 177 case XK_BackSpace: 178 if (len) 179 passwd[--len] = '\0'; 180 break; 181 default: 182 if (num && !iscntrl((unsigned char)buf[0]) && 183 (len + num < sizeof(passwd))) { 184 memcpy(passwd + len, buf, num); 185 len += num; 186 } else if (buf[0] == '\025') { /* ctrl-u clears input */ 187 explicit_bzero(&passwd, sizeof(passwd)); 188 len = 0; 189 } 190 break; 191 } 192 color = len ? INPUT : ((failure || failonclear) ? FAILED : INIT); 193 if (running && oldc != color) { 194 for (screen = 0; screen < nscreens; screen++) { 195 XSetWindowBackground(dpy, 196 locks[screen]->win, 197 locks[screen]->colors[color]); 198 XClearWindow(dpy, locks[screen]->win); 199 } 200 oldc = color; 201 } 202 } else if (rr->active && ev.type == rr->evbase + RRScreenChangeNotify) { 203 rre = (XRRScreenChangeNotifyEvent*)&ev; 204 for (screen = 0; screen < nscreens; screen++) { 205 if (locks[screen]->win == rre->window) { 206 if (rre->rotation == RR_Rotate_90 || 207 rre->rotation == RR_Rotate_270) 208 XResizeWindow(dpy, locks[screen]->win, 209 rre->height, rre->width); 210 else 211 XResizeWindow(dpy, locks[screen]->win, 212 rre->width, rre->height); 213 XClearWindow(dpy, locks[screen]->win); 214 break; 215 } 216 } 217 } else { 218 for (screen = 0; screen < nscreens; screen++) 219 XRaiseWindow(dpy, locks[screen]->win); 220 } 221 } 222 } 223 224 static struct lock * 225 lockscreen(Display *dpy, struct xrandr *rr, int screen) 226 { 227 char curs[] = {0, 0, 0, 0, 0, 0, 0, 0}; 228 int i, ptgrab, kbgrab; 229 struct lock *lock; 230 XColor color, dummy; 231 XSetWindowAttributes wa; 232 Cursor invisible; 233 234 if (dpy == NULL || screen < 0 || !(lock = malloc(sizeof(struct lock)))) 235 return NULL; 236 237 lock->screen = screen; 238 lock->root = RootWindow(dpy, lock->screen); 239 240 for (i = 0; i < NUMCOLS; i++) { 241 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), 242 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, 250 DisplayWidth(dpy, lock->screen), 251 DisplayHeight(dpy, lock->screen), 252 0, DefaultDepth(dpy, lock->screen), 253 CopyFromParent, 254 DefaultVisual(dpy, lock->screen), 255 CWOverrideRedirect | CWBackPixel, &wa); 256 lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8); 257 invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, 258 &color, &color, 0, 0); 259 XDefineCursor(dpy, lock->win, invisible); 260 261 /* Try to grab mouse pointer *and* keyboard for 600ms, else fail the lock */ 262 for (i = 0, ptgrab = kbgrab = -1; i < 6; i++) { 263 if (ptgrab != GrabSuccess) { 264 ptgrab = XGrabPointer(dpy, lock->root, False, 265 ButtonPressMask | ButtonReleaseMask | 266 PointerMotionMask, GrabModeAsync, 267 GrabModeAsync, None, invisible, CurrentTime); 268 } 269 if (kbgrab != GrabSuccess) { 270 kbgrab = XGrabKeyboard(dpy, lock->root, True, 271 GrabModeAsync, GrabModeAsync, CurrentTime); 272 } 273 274 /* input is grabbed: we can lock the screen */ 275 if (ptgrab == GrabSuccess && kbgrab == GrabSuccess) { 276 XMapRaised(dpy, lock->win); 277 if (rr->active) 278 XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask); 279 280 XSelectInput(dpy, lock->root, SubstructureNotifyMask); 281 return lock; 282 } 283 284 /* retry on AlreadyGrabbed but fail on other errors */ 285 if ((ptgrab != AlreadyGrabbed && ptgrab != GrabSuccess) || 286 (kbgrab != AlreadyGrabbed && kbgrab != GrabSuccess)) 287 break; 288 289 usleep(100000); 290 } 291 292 /* we couldn't grab all input: fail out */ 293 if (ptgrab != GrabSuccess) 294 fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n", 295 screen); 296 if (kbgrab != GrabSuccess) 297 fprintf(stderr, "slock: unable to grab keyboard for screen %d\n", 298 screen); 299 return NULL; 300 } 301 302 static void 303 usage(void) 304 { 305 die("usage: slock [-v]\n"); 306 } 307 308 int 309 main(int argc, char **argv) { 310 struct xrandr rr; 311 struct lock **locks; 312 struct passwd *pwd; 313 struct group *grp; 314 uid_t duid; 315 gid_t dgid; 316 const char *hash; 317 Display *dpy; 318 int s, nlocks, nscreens; 319 320 if (argc > 1 && !strcmp(argv[1], "-v")) { 321 puts("slock-"VERSION); 322 return 0; 323 } else if (argc > 1) { 324 usage(); 325 } 326 327 /* validate drop-user and -group */ 328 errno = 0; 329 if (!(pwd = getpwnam(user))) 330 die("slock: getpwnam %s: %s\n", user, 331 errno ? strerror(errno) : "user entry not found"); 332 duid = pwd->pw_uid; 333 errno = 0; 334 if (!(grp = getgrnam(group))) 335 die("slock: getgrnam %s: %s\n", group, 336 errno ? strerror(errno) : "group entry not found"); 337 dgid = grp->gr_gid; 338 339 #ifdef __linux__ 340 dontkillme(); 341 #endif 342 343 hash = gethash(); 344 errno = 0; 345 if (!crypt("", hash)) 346 die("slock: crypt: %s\n", strerror(errno)); 347 348 if (!(dpy = XOpenDisplay(NULL))) 349 die("slock: cannot open display\n"); 350 351 /* drop privileges */ 352 if (setgroups(0, NULL) < 0) 353 die("slock: setgroups: %s\n", strerror(errno)); 354 if (setgid(dgid) < 0) 355 die("slock: setgid: %s\n", strerror(errno)); 356 if (setuid(duid) < 0) 357 die("slock: setuid: %s\n", strerror(errno)); 358 359 /* check for Xrandr support */ 360 rr.active = XRRQueryExtension(dpy, &rr.evbase, &rr.errbase); 361 362 /* get number of screens in display "dpy" and blank them */ 363 nscreens = ScreenCount(dpy); 364 if (!(locks = calloc(nscreens, sizeof(struct lock *)))) 365 die("slock: out of memory\n"); 366 for (nlocks = 0, s = 0; s < nscreens; s++) { 367 if ((locks[s] = lockscreen(dpy, &rr, s)) != NULL) 368 nlocks++; 369 else 370 break; 371 } 372 XSync(dpy, 0); 373 374 /* did we manage to lock everything? */ 375 if (nlocks != nscreens) 376 return 1; 377 378 /* everything is now blank. Wait for the correct password */ 379 readpw(dpy, &rr, locks, nscreens, hash); 380 381 return 0; 382 }