slock-noxz

[fork] simple X display locker utility
git clone git://git.noxz.tech/slock-noxz
Log | Files | Refs | README | LICENSE

commit 23d12cad23a7eca39b5a440d0a5bdc3f8c2be97e
Author: Chris Noxz <chris@noxz.tech>
Date:   Thu, 19 Sep 2019 14:40:11 +0200

Initial commit based on slock commit up to
35633d45672d14bd798c478c45d1a17064701aa9

Diffstat:
ALICENSE | 24++++++++++++++++++++++++
AMakefile | 61+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
AREADME | 24++++++++++++++++++++++++
Aarg.h | 65+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Aconfig.def.h | 12++++++++++++
Aconfig.mk | 32++++++++++++++++++++++++++++++++
Aexplicit_bzero.c | 19+++++++++++++++++++
Aslock.1 | 39+++++++++++++++++++++++++++++++++++++++
Aslock.c | 395+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Autil.h | 2++
10 files changed, 673 insertions(+), 0 deletions(-)

diff --git a/LICENSE b/LICENSE @@ -0,0 +1,24 @@ +MIT/X Consortium License + +© 2015-2016 Markus Teich <markus.teich@stusta.mhn.de> +© 2014 Dimitris Papastamos <sin@2f30.org> +© 2006-2014 Anselm R Garbe <anselm@garbe.us> +© 2014-2016 Laslo Hunhold <dev@frign.de> + +Permission is hereby granted, free of charge, to any person obtaining a +copy of this software and associated documentation files (the "Software"), +to deal in the Software without restriction, including without limitation +the rights to use, copy, modify, merge, publish, distribute, sublicense, +and/or sell copies of the Software, and to permit persons to whom the +Software is furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in +all copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL +THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING +FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER +DEALINGS IN THE SOFTWARE. diff --git a/Makefile b/Makefile @@ -0,0 +1,61 @@ +# slock - simple screen locker +# See LICENSE file for copyright and license details. + +include config.mk + +SRC = slock.c ${COMPATSRC} +OBJ = ${SRC:.c=.o} + +all: options slock + +options: + @echo slock build options: + @echo "CFLAGS = ${CFLAGS}" + @echo "LDFLAGS = ${LDFLAGS}" + @echo "CC = ${CC}" + +.c.o: + @echo CC $< + @${CC} -c ${CFLAGS} $< + +${OBJ}: config.h config.mk arg.h util.h + +config.h: + @echo creating $@ from config.def.h + @cp config.def.h $@ + +slock: ${OBJ} + @echo CC -o $@ + @${CC} -o $@ ${OBJ} ${LDFLAGS} + +clean: + @echo cleaning + @rm -f slock ${OBJ} slock-${VERSION}.tar.gz + +dist: clean + @echo creating dist tarball + @mkdir -p slock-${VERSION} + @cp -R LICENSE Makefile README slock.1 config.mk \ + ${SRC} explicit_bzero.c config.def.h arg.h util.h slock-${VERSION} + @tar -cf slock-${VERSION}.tar slock-${VERSION} + @gzip slock-${VERSION}.tar + @rm -rf slock-${VERSION} + +install: all + @echo installing executable file to ${DESTDIR}${PREFIX}/bin + @mkdir -p ${DESTDIR}${PREFIX}/bin + @cp -f slock ${DESTDIR}${PREFIX}/bin + @chmod 755 ${DESTDIR}${PREFIX}/bin/slock + @chmod u+s ${DESTDIR}${PREFIX}/bin/slock + @echo installing manual page to ${DESTDIR}${MANPREFIX}/man1 + @mkdir -p ${DESTDIR}${MANPREFIX}/man1 + @sed "s/VERSION/${VERSION}/g" <slock.1 >${DESTDIR}${MANPREFIX}/man1/slock.1 + @chmod 644 ${DESTDIR}${MANPREFIX}/man1/slock.1 + +uninstall: + @echo removing executable file from ${DESTDIR}${PREFIX}/bin + @rm -f ${DESTDIR}${PREFIX}/bin/slock + @echo removing manual page from ${DESTDIR}${MANPREFIX}/man1 + @rm -f ${DESTDIR}${MANPREFIX}/man1/slock.1 + +.PHONY: all options clean dist install uninstall diff --git a/README b/README @@ -0,0 +1,24 @@ +slock - simple screen locker +============================ +simple screen locker utility for X. + + +Requirements +------------ +In order to build slock you need the Xlib header files. + + +Installation +------------ +Edit config.mk to match your local setup (slock is installed into +the /usr/local namespace by default). + +Afterwards enter the following command to build and install slock +(if necessary as root): + + make clean install + + +Running slock +------------- +Simply invoke the 'slock' command. To get out of it, enter your password. diff --git a/arg.h b/arg.h @@ -0,0 +1,65 @@ +/* + * Copy me if you can. + * by 20h + */ + +#ifndef ARG_H__ +#define ARG_H__ + +extern char *argv0; + +/* use main(int argc, char *argv[]) */ +#define ARGBEGIN for (argv0 = *argv, argv++, argc--;\ + argv[0] && argv[0][0] == '-'\ + && argv[0][1];\ + argc--, argv++) {\ + char argc_;\ + char **argv_;\ + int brk_;\ + if (argv[0][1] == '-' && argv[0][2] == '\0') {\ + argv++;\ + argc--;\ + break;\ + }\ + for (brk_ = 0, argv[0]++, argv_ = argv;\ + argv[0][0] && !brk_;\ + argv[0]++) {\ + if (argv_ != argv)\ + break;\ + argc_ = argv[0][0];\ + switch (argc_) + +/* Handles obsolete -NUM syntax */ +#define ARGNUM case '0':\ + case '1':\ + case '2':\ + case '3':\ + case '4':\ + case '5':\ + case '6':\ + case '7':\ + case '8':\ + case '9' + +#define ARGEND }\ + } + +#define ARGC() argc_ + +#define ARGNUMF() (brk_ = 1, estrtonum(argv[0], 0, INT_MAX)) + +#define EARGF(x) ((argv[0][1] == '\0' && argv[1] == NULL)?\ + ((x), abort(), (char *)0) :\ + (brk_ = 1, (argv[0][1] != '\0')?\ + (&argv[0][1]) :\ + (argc--, argv++, argv[0]))) + +#define ARGF() ((argv[0][1] == '\0' && argv[1] == NULL)?\ + (char *)0 :\ + (brk_ = 1, (argv[0][1] != '\0')?\ + (&argv[0][1]) :\ + (argc--, argv++, argv[0]))) + +#define LNGARG() &argv[0][0] + +#endif diff --git a/config.def.h b/config.def.h @@ -0,0 +1,12 @@ +/* user and group to drop privileges to */ +static const char *user = "nobody"; +static const char *group = "nogroup"; + +static const char *colorname[NUMCOLS] = { + [INIT] = "black", /* after initialization */ + [INPUT] = "#005577", /* during input */ + [FAILED] = "#CC3333", /* wrong password */ +}; + +/* treat a cleared input like a wrong password (color) */ +static const int failonclear = 1; diff --git a/config.mk b/config.mk @@ -0,0 +1,32 @@ +# slock version +VERSION = 1.4 + +# Customize below to fit your system + +# paths +PREFIX = /usr/local +MANPREFIX = ${PREFIX}/share/man + +X11INC = /usr/X11R6/include +X11LIB = /usr/X11R6/lib + +# includes and libs +INCS = -I. -I/usr/include -I${X11INC} +LIBS = -L/usr/lib -lc -lcrypt -L${X11LIB} -lX11 -lXext -lXrandr + +# flags +CPPFLAGS = -DVERSION=\"${VERSION}\" -D_DEFAULT_SOURCE -DHAVE_SHADOW_H +CFLAGS = -std=c99 -pedantic -Wall -Os ${INCS} ${CPPFLAGS} +LDFLAGS = -s ${LIBS} +COMPATSRC = explicit_bzero.c + +# On OpenBSD and Darwin remove -lcrypt from LIBS +#LIBS = -L/usr/lib -lc -L${X11LIB} -lX11 -lXext -lXrandr +# On *BSD remove -DHAVE_SHADOW_H from CPPFLAGS +# On NetBSD add -D_NETBSD_SOURCE to CPPFLAGS +#CPPFLAGS = -DVERSION=\"${VERSION}\" -D_BSD_SOURCE -D_NETBSD_SOURCE +# On OpenBSD set COMPATSRC to empty +#COMPATSRC = + +# compiler and linker +CC = cc diff --git a/explicit_bzero.c b/explicit_bzero.c @@ -0,0 +1,19 @@ +/* $OpenBSD: explicit_bzero.c,v 1.3 2014/06/21 02:34:26 matthew Exp $ */ +/* + * Public domain. + * Written by Matthew Dempsky. + */ + +#include <string.h> + +__attribute__((weak)) void +__explicit_bzero_hook(void *buf, size_t len) +{ +} + +void +explicit_bzero(void *buf, size_t len) +{ + memset(buf, 0, len); + __explicit_bzero_hook(buf, len); +} diff --git a/slock.1 b/slock.1 @@ -0,0 +1,39 @@ +.Dd 2016-08-23 +.Dt SLOCK 1 +.Sh NAME +.Nm slock +.Nd simple X screen locker +.Sh SYNOPSIS +.Nm +.Op Fl v +.Op Ar cmd Op Ar arg ... +.Sh DESCRIPTION +.Nm +is a simple X screen locker. If provided, +.Ar cmd Op Ar arg ... +is executed after the screen has been locked. +.Sh OPTIONS +.Bl -tag -width Ds +.It Fl v +Print version information to stdout and exit. +.El +.Sh SECURITY CONSIDERATIONS +To make sure a locked screen can not be bypassed by switching VTs +or killing the X server with Ctrl+Alt+Backspace, it is recommended +to disable both in +.Xr xorg.conf 5 +for maximum security: +.Bd -literal -offset left +Section "ServerFlags" + Option "DontVTSwitch" "True" + Option "DontZap" "True" +EndSection +.Ed +.Sh EXAMPLES +$ +.Nm +/usr/sbin/s2ram +.Sh CUSTOMIZATION +.Nm +can be customized by creating a custom config.h from config.def.h and +(re)compiling the source code. This keeps it fast, secure and simple. diff --git a/slock.c b/slock.c @@ -0,0 +1,395 @@ +/* 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 <grp.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> + +#include "arg.h" +#include "util.h" + +char *argv0; + +enum { + INIT, + INPUT, + FAILED, + NUMCOLS +}; + +struct lock { + int screen; + Window root, win; + Pixmap pmap; + unsigned long colors[NUMCOLS]; +}; + +struct xrandr { + int active; + int evbase; + int errbase; +}; + +#include "config.h" + +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> +#include <linux/oom.h> + +static void +dontkillme(void) +{ + FILE *f; + const char oomfile[] = "/proc/self/oom_score_adj"; + + if (!(f = fopen(oomfile, "w"))) { + if (errno == ENOENT) + return; + die("slock: fopen %s: %s\n", oomfile, strerror(errno)); + } + fprintf(f, "%d", OOM_SCORE_ADJ_MIN); + if (fclose(f)) { + if (errno == EACCES) + die("slock: unable to disable OOM killer. " + "Make sure to suid or sgid slock.\n"); + else + die("slock: fclose %s: %s\n", oomfile, strerror(errno)); + } +} +#endif + +static const char * +gethash(void) +{ + const char *hash; + struct passwd *pw; + + /* Check if the current user has a password entry */ + errno = 0; + if (!(pw = getpwuid(getuid()))) { + if (errno) + die("slock: getpwuid: %s\n", strerror(errno)); + else + die("slock: cannot retrieve password entry\n"); + } + hash = pw->pw_passwd; + +#if HAVE_SHADOW_H + if (!strcmp(hash, "x")) { + struct spwd *sp; + if (!(sp = getspnam(pw->pw_name))) + die("slock: getspnam: cannot retrieve shadow entry. " + "Make sure to suid or sgid slock.\n"); + hash = sp->sp_pwdp; + } +#else + if (!strcmp(hash, "*")) { +#ifdef __OpenBSD__ + if (!(pw = getpwuid_shadow(getuid()))) + die("slock: getpwnam_shadow: cannot retrieve shadow entry. " + "Make sure to suid or sgid slock.\n"); + hash = pw->pw_passwd; +#else + die("slock: getpwuid: cannot retrieve shadow entry. " + "Make sure to suid or sgid slock.\n"); +#endif /* __OpenBSD__ */ + } +#endif /* HAVE_SHADOW_H */ + + return hash; +} + +static void +readpw(Display *dpy, struct xrandr *rr, struct lock **locks, int nscreens, + const char *hash) +{ + XRRScreenChangeNotifyEvent *rre; + char buf[32], passwd[256], *inputhash; + int num, screen, running, failure, oldc; + unsigned int len, color; + KeySym ksym; + XEvent ev; + + len = 0; + running = 1; + failure = 0; + oldc = INIT; + + 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'; + errno = 0; + if (!(inputhash = crypt(passwd, hash))) + fprintf(stderr, "slock: crypt: %s\n", strerror(errno)); + else + running = !!strcmp(inputhash, hash); + if (running) { + XBell(dpy, 100); + failure = 1; + } + 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->active && ev.type == rr->evbase + RRScreenChangeNotify) { + rre = (XRRScreenChangeNotifyEvent*)&ev; + for (screen = 0; screen < nscreens; screen++) { + if (locks[screen]->win == rre->window) { + if (rre->rotation == RR_Rotate_90 || + rre->rotation == RR_Rotate_270) + XResizeWindow(dpy, locks[screen]->win, + rre->height, rre->width); + else + XResizeWindow(dpy, locks[screen]->win, + rre->width, rre->height); + XClearWindow(dpy, locks[screen]->win); + break; + } + } + } else { + for (screen = 0; screen < nscreens; screen++) + XRaiseWindow(dpy, locks[screen]->win); + } + } +} + +static struct lock * +lockscreen(Display *dpy, struct xrandr *rr, int screen) +{ + char curs[] = {0, 0, 0, 0, 0, 0, 0, 0}; + int i, ptgrab, kbgrab; + struct lock *lock; + XColor color, dummy; + XSetWindowAttributes wa; + Cursor invisible; + + if (dpy == NULL || screen < 0 || !(lock = malloc(sizeof(struct 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 for 600ms, else fail the lock */ + for (i = 0, ptgrab = kbgrab = -1; i < 6; i++) { + if (ptgrab != GrabSuccess) { + ptgrab = XGrabPointer(dpy, lock->root, False, + ButtonPressMask | ButtonReleaseMask | + PointerMotionMask, GrabModeAsync, + GrabModeAsync, None, invisible, CurrentTime); + } + if (kbgrab != GrabSuccess) { + kbgrab = XGrabKeyboard(dpy, lock->root, True, + GrabModeAsync, GrabModeAsync, CurrentTime); + } + + /* input is grabbed: we can lock the screen */ + if (ptgrab == GrabSuccess && kbgrab == GrabSuccess) { + XMapRaised(dpy, lock->win); + if (rr->active) + XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask); + + XSelectInput(dpy, lock->root, SubstructureNotifyMask); + return lock; + } + + /* retry on AlreadyGrabbed but fail on other errors */ + if ((ptgrab != AlreadyGrabbed && ptgrab != GrabSuccess) || + (kbgrab != AlreadyGrabbed && kbgrab != GrabSuccess)) + break; + + usleep(100000); + } + + /* we couldn't grab all input: fail out */ + if (ptgrab != GrabSuccess) + fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n", + screen); + if (kbgrab != GrabSuccess) + fprintf(stderr, "slock: unable to grab keyboard for screen %d\n", + screen); + return NULL; +} + +static void +usage(void) +{ + die("usage: slock [-v] [cmd [arg ...]]\n"); +} + +int +main(int argc, char **argv) { + struct xrandr rr; + struct lock **locks; + struct passwd *pwd; + struct group *grp; + uid_t duid; + gid_t dgid; + const char *hash; + Display *dpy; + int s, nlocks, nscreens; + + ARGBEGIN { + case 'v': + fprintf(stderr, "slock-"VERSION"\n"); + return 0; + default: + usage(); + } ARGEND + + /* validate drop-user and -group */ + errno = 0; + if (!(pwd = getpwnam(user))) + die("slock: getpwnam %s: %s\n", user, + errno ? strerror(errno) : "user entry not found"); + duid = pwd->pw_uid; + errno = 0; + if (!(grp = getgrnam(group))) + die("slock: getgrnam %s: %s\n", group, + errno ? strerror(errno) : "group entry not found"); + dgid = grp->gr_gid; + +#ifdef __linux__ + dontkillme(); +#endif + + hash = gethash(); + errno = 0; + if (!crypt("", hash)) + die("slock: crypt: %s\n", strerror(errno)); + + if (!(dpy = XOpenDisplay(NULL))) + die("slock: cannot open display\n"); + + /* drop privileges */ + if (setgroups(0, NULL) < 0) + die("slock: setgroups: %s\n", strerror(errno)); + if (setgid(dgid) < 0) + die("slock: setgid: %s\n", strerror(errno)); + if (setuid(duid) < 0) + die("slock: setuid: %s\n", strerror(errno)); + + /* check for Xrandr support */ + rr.active = XRRQueryExtension(dpy, &rr.evbase, &rr.errbase); + + /* get number of screens in display "dpy" and blank them */ + nscreens = ScreenCount(dpy); + if (!(locks = calloc(nscreens, sizeof(struct lock *)))) + die("slock: out of memory\n"); + for (nlocks = 0, s = 0; s < nscreens; s++) { + if ((locks[s] = lockscreen(dpy, &rr, s)) != NULL) + nlocks++; + else + break; + } + XSync(dpy, 0); + + /* did we manage to lock everything? */ + if (nlocks != nscreens) + return 1; + + /* run post-lock command */ + if (argc > 0) { + switch (fork()) { + case -1: + 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 */ + readpw(dpy, &rr, locks, nscreens, hash); + + return 0; +} diff --git a/util.h b/util.h @@ -0,0 +1,2 @@ +#undef explicit_bzero +void explicit_bzero(void *, size_t);