]> git.armaanb.net Git - slock.git/blobdiff - slock.c
add hint for suid to oom error message
[slock.git] / slock.c
diff --git a/slock.c b/slock.c
index 2dc96483426b360fe8c051e7776c13cf0530f35f..fa7ec8428afb91be37198d7c2b035539a6719534 100644 (file)
--- a/slock.c
+++ b/slock.c
@@ -1,11 +1,11 @@
-/* © 2006-2008 Anselm R Garbe <garbeam at gmail dot com>
- * See LICENSE file for license details. */
+/* 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 <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>
-#include <X11/extensions/dpms.h>
 
 #if HAVE_BSD_AUTH
 #include <login_cap.h>
 #include <bsd_auth.h>
 #endif
 
-void
-eprint(const char *errstr, ...) {
+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(EXIT_FAILURE);
+       exit(1);
+}
+
+#ifdef __linux__
+#include <fcntl.h>
+#include <linux/oom.h>
+
+static void
+dontkillme(void)
+{
+       int fd;
+       int length;
+       char value[64];
+
+       fd = open("/proc/self/oom_score_adj", O_WRONLY);
+       if (fd < 0 && errno == ENOENT)
+               return;
+
+       /* convert OOM_SCORE_ADJ_MIN to string for writing */
+       length = snprintf(value, sizeof(value), "%d\n", OOM_SCORE_ADJ_MIN);
+
+       /* bail on truncation */
+       if (length >= sizeof(value))
+               die("buffer too small\n");
+
+       if (fd < 0 || write(fd, value, length) != length || close(fd) != 0)
+               die("cannot disable the out-of-memory killer for this process (make sure to suid or sgid slock)\n");
 }
+#endif
 
 #ifndef HAVE_BSD_AUTH
-const char *
-get_password() { /* only run as root */
+/* only run as root */
+static const char *
+getpw(void)
+{
        const char *rval;
        struct passwd *pw;
 
-       if(geteuid() != 0)
-               eprint("slock: cannot retrieve password entry (make sure to suid slock)\n");
-       pw = getpwuid(getuid());
-       endpwent();
-       rval =  pw->pw_passwd;
+       errno = 0;
+       if (!(pw = getpwuid(getuid()))) {
+               if (errno)
+                       die("slock: getpwuid: %s\n", strerror(errno));
+               else
+                       die("slock: cannot retrieve password entry\n");
+       }
+       rval = pw->pw_passwd;
 
 #if HAVE_SHADOW_H
-       {
+       if (rval[0] == 'x' && rval[1] == '\0') {
                struct spwd *sp;
-               sp = getspnam(getenv("USER"));
-               endspent();
+               if (!(sp = getspnam(getenv("USER"))))
+                       die("slock: cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
                rval = sp->sp_pwdp;
        }
 #endif
 
        /* drop privileges */
-       if(setgid(pw->pw_gid) < 0 || setuid(pw->pw_uid) < 0)
-               eprint("slock: cannot drop privileges\n");
+       if (geteuid() == 0 &&
+           ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
+               die("slock: cannot drop privileges\n");
        return rval;
 }
 #endif
 
-int
-main(int argc, char **argv) {
-       char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
+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;
-
-#ifndef HAVE_BSD_AUTH
-       const char *pws;
-#endif
-       unsigned int len;
-       Bool running = True;
-       Cursor invisible;
-       Display *dpy;
+       unsigned int len, color;
        KeySym ksym;
-       Pixmap pmap;
-       Window root, w;
-       XColor black, dummy;
        XEvent ev;
-       XSetWindowAttributes wa;
-
-       if((argc == 2) && !strcmp("-v", argv[1]))
-               eprint("slock-"VERSION", © 2006-2008 Anselm R Garbe\n");
-       else if(argc != 1)
-               eprint("usage: slock [-v]\n");
+       static int oldc = INIT;
 
-#ifndef HAVE_BSD_AUTH
-       pws = get_password();
-#endif
-
-       if(!(dpy = XOpenDisplay(0)))
-               eprint("slock: cannot open display\n");
-       screen = DefaultScreen(dpy);
-       root = RootWindow(dpy, screen);
-
-       /* init */
-       wa.override_redirect = 1;
-       wa.background_pixel = BlackPixel(dpy, screen);
-       w = XCreateWindow(dpy, root, 0, 0, DisplayWidth(dpy, screen), DisplayHeight(dpy, screen),
-                       0, DefaultDepth(dpy, screen), CopyFromParent,
-                       DefaultVisual(dpy, screen), CWOverrideRedirect | CWBackPixel, &wa);
-       XAllocNamedColor(dpy, DefaultColormap(dpy, screen), "black", &black, &dummy);
-       pmap = XCreateBitmapFromData(dpy, w, curs, 8, 8);
-       invisible = XCreatePixmapCursor(dpy, pmap, pmap, &black, &black, 0, 0);
-       XDefineCursor(dpy, w, invisible);
-       XMapRaised(dpy, w);
-       for(len = 1000; len; len--) {
-               if(XGrabPointer(dpy, root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
-                       GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
-                       break;
-               usleep(1000);
-       }
-       if((running = running && (len > 0))) {
-               for(len = 1000; len; len--) {
-                       if(XGrabKeyboard(dpy, root, True, GrabModeAsync, GrabModeAsync, CurrentTime)
-                               == GrabSuccess)
-                               break;
-                       usleep(1000);
-               }
-               running = (len > 0);
-       }
        len = 0;
-       XSync(dpy, False);
+       running = True;
 
-       /* main event loop */
-       while(running && !XNextEvent(dpy, &ev)) {
-               if(len == 0) 
-                       DPMSForceLevel(dpy, DPMSModeOff);
-               if(ev.type == KeyPress) {
+       /* 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) {
                        buf[0] = 0;
-                       num = XLookupString(&ev.xkey, buf, sizeof buf, &ksym, 0);
-                       if(IsFunctionKey(ksym) || IsKeypadKey(ksym)
-                                       || IsMiscFunctionKey(ksym) || IsPFKey(ksym)
-                                       || IsPrivateKeypadKey(ksym))
+                       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) {
+                       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);
+                               running = !!strcmp(crypt(passwd, pws), pws);
 #endif
-
-                               if (running != 0)
+                               if (running) {
                                        XBell(dpy, 100);
+                                       failure = True;
+                               }
                                len = 0;
                                break;
                        case XK_Escape:
                                len = 0;
                                break;
                        case XK_BackSpace:
-                               if(len)
+                               if (len)
                                        --len;
                                break;
                        default:
-                               if(num && !iscntrl((int) buf[0]) && (len + num < sizeof passwd)) { 
+                               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);
-       XFreePixmap(dpy, pmap);
-       XDestroyWindow(dpy, w);
+       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};
+       unsigned int len;
+       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);
+       XMapRaised(dpy, lock->win);
+       if (rr)
+               XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
+
+       /* Try to grab mouse pointer *and* keyboard, else fail the lock */
+       for (len = 1000; len; len--) {
+               if (XGrabPointer(dpy, lock->root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
+                   GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
+                       break;
+               usleep(1000);
+       }
+       if (!len) {
+               fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n", screen);
+       } else {
+               for (len = 1000; len; len--) {
+                       if (XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync, CurrentTime) == GrabSuccess) {
+                               /* everything fine, we grabbed both inputs */
+                               XSelectInput(dpy, lock->root, SubstructureNotifyMask);
+                               return lock;
+                       }
+                       usleep(1000);
+               }
+               fprintf(stderr, "slock: unable to grab keyboard for screen %d\n", screen);
+       }
+       /* grabbing one of the inputs failed */
+       running = 0;
+       unlockscreen(dpy, lock);
+       return NULL;
+}
+
+static void
+usage(void)
+{
+       fprintf(stderr, "usage: slock [-v|POST_LOCK_CMD]\n");
+       exit(1);
+}
+
+int
+main(int argc, char **argv) {
+#ifndef HAVE_BSD_AUTH
+       const char *pws;
+#endif
+       Display *dpy;
+       int screen;
+
+       if ((argc == 2) && !strcmp("-v", argv[1]))
+               die("slock-%s, © 2006-2015 slock engineers\n", VERSION);
+
+       if ((argc == 2) && !strcmp("-h", argv[1]))
+               usage();
+
+#ifdef __linux__
+       dontkillme();
+#endif
+
+       if (!getpwuid(getuid()))
+               die("slock: no passwd entry for you\n");
+
+#ifndef HAVE_BSD_AUTH
+       pws = getpw();
+#endif
+
+       if (!(dpy = XOpenDisplay(0)))
+               die("slock: cannot open display\n");
+       rr = XRRQueryExtension(dpy, &rrevbase, &rrerrbase);
+       /* Get the number of screens in display "dpy" and blank them all. */
+       nscreens = ScreenCount(dpy);
+       if (!(locks = malloc(sizeof(Lock*) * nscreens)))
+               die("slock: malloc: %s\n", strerror(errno));
+       int nlocks = 0;
+       for (screen = 0; screen < nscreens; screen++) {
+               if ((locks[screen] = lockscreen(dpy, screen)) != NULL)
+                       nlocks++;
+       }
+       XSync(dpy, False);
+
+       /* Did we actually manage to lock something? */
+       if (nlocks == 0) { /* nothing to protect */
+               free(locks);
+               XCloseDisplay(dpy);
+               return 1;
+       }
+
+       if (argc >= 2 && fork() == 0) {
+               if (dpy)
+                       close(ConnectionNumber(dpy));
+               execvp(argv[1], argv+1);
+               die("slock: execvp %s failed: %s\n", argv[1], strerror(errno));
+       }
+
+       /* Everything is now blank. Now wait for the correct password. */
+#ifdef HAVE_BSD_AUTH
+       readpw(dpy);
+#else
+       readpw(dpy, pws);
+#endif
+
+       /* Password ok, unlock everything and quit. */
+       for (screen = 0; screen < nscreens; screen++)
+               unlockscreen(dpy, locks[screen]);
+
+       free(locks);
        XCloseDisplay(dpy);
+
        return 0;
 }