New utility: xbps-uunshare(8) - like xbps-uchroot(8) with user_namespaces(7).
This commit is contained in:
Juan RP
parent
927254c43e
commit
58e6d71d24
4
NEWS
4
NEWS
@ -1,5 +1,9 @@
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xbps-0.44 (???):
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* xbps-uunshare(8): new utility analogue to xbps-uchroot(8), but uses
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user namespaces (see user_namespaces(7)) to avoid the need of elevated
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privileges.
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* xbps-rindex(8): fix -s short option; was omitted in the short options list.
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* xbps-pkgdb(8): added a new mode to set in installed packages: "repolock".
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@ -10,6 +10,7 @@ SUBDIRS += xbps-remove
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SUBDIRS += xbps-rindex
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SUBDIRS += xbps-uhelper
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SUBDIRS += xbps-checkvers
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SUBDIRS += xbps-uunshare
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ifeq (${XBPS_OS},linux)
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SUBDIRS += xbps-uchroot
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6
bin/xbps-uunshare/Makefile
Normal file
6
bin/xbps-uunshare/Makefile
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@ -0,0 +1,6 @@
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TOPDIR = ../..
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-include $(TOPDIR)/config.mk
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BIN = xbps-uunshare
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include $(TOPDIR)/mk/prog.mk
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206
bin/xbps-uunshare/main.c
Normal file
206
bin/xbps-uunshare/main.c
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@ -0,0 +1,206 @@
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/*-
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* Copyright (c) 2014-2015 Juan Romero Pardines.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#define _GNU_SOURCE
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#include <sys/types.h>
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#include <sys/mount.h>
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#include <sys/fsuid.h>
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#include <sys/wait.h>
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#include <sched.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <stdarg.h>
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#include <signal.h>
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#include <fcntl.h>
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#include <grp.h>
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#include <errno.h>
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#include <limits.h>
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#include <syscall.h>
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static int errval = 0;
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static void __attribute__((noreturn))
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die(const char *fmt, ...)
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{
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va_list ap;
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int save_errno = errno;
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va_start(ap, fmt);
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fprintf(stderr, "ERROR ");
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vfprintf(stderr, fmt, ap);
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fprintf(stderr, " (%s)\n", strerror(save_errno));
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va_end(ap);
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exit(errval != 0 ? errval : EXIT_FAILURE);
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}
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static void __attribute__((noreturn))
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usage(const char *p)
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{
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printf("Usage: %s [-D dir] [-H dir] [-S dir] <chrootdir> <command>\n\n"
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"-D <distdir> Directory to be bind mounted at <chrootdir>/void-packages\n"
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"-H <hostdir> Directory to be bind mounted at <chrootdir>/host\n"
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"-S <shmdir> Directory to be bind mounted at <chrootdir>/<shmdir>\n", p);
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exit(EXIT_FAILURE);
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}
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static void
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bindmount(const char *chrootdir, const char *dir, const char *dest)
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{
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char mountdir[PATH_MAX-1];
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snprintf(mountdir, sizeof(mountdir), "%s/%s", chrootdir, dest ? dest : dir);
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if (mount(".", mountdir, NULL, MS_BIND|MS_REC|MS_PRIVATE, NULL) == -1)
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die("Failed to bind mount %s at %s", dir, mountdir);
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}
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int
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main(int argc, char **argv)
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{
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uid_t uid = getuid();
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gid_t gid = getgid();
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const char *chrootdir, *distdir, *hostdir, *shmdir, *cmd, *argv0;
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char **cmdargs, mountdir[PATH_MAX-1], buf[32];
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int fd, aidx = 0, clone_flags, child_status = 0;
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pid_t child;
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chrootdir = distdir = hostdir = shmdir = cmd = NULL;
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argv0 = argv[0];
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argc--;
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argv++;
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if (argc < 2)
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usage(argv0);
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while (aidx < argc) {
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if (strcmp(argv[aidx], "-D") == 0) {
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/* distdir */
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distdir = argv[aidx+1];
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aidx += 2;
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} else if (strcmp(argv[aidx], "-H") == 0) {
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/* hostdir */
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hostdir = argv[aidx+1];
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aidx += 2;
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} else if (strcmp(argv[aidx], "-S") == 0) {
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/* shmdir */
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shmdir = argv[aidx+1];
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aidx += 2;
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} else {
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break;
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}
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}
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if ((argc - aidx) < 2)
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usage(argv0);
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chrootdir = argv[aidx];
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cmd = argv[aidx+1];
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cmdargs = argv + aidx + 1;
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/* Never allow chrootdir == / */
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if (strcmp(chrootdir, "/") == 0)
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die("/ is not allowed to be used as chrootdir");
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clone_flags = (SIGCHLD|CLONE_NEWUSER|CLONE_NEWNS|CLONE_NEWIPC|CLONE_NEWUTS|CLONE_NEWPID);
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/* Issue the clone(2) syscall with our settings */
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if ((child = syscall(__NR_clone, clone_flags, NULL)) == -1) {
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errval = 99;
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die("clone");
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}
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if (child == 0) {
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/*
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* Setup uid/gid user mappings and restrict setgroups().
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*/
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if ((fd = open("/proc/self/uid_map", O_RDWR)) == -1)
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die("failed to open /proc/self/uidmap rw");
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if (write(fd, buf, snprintf(buf, sizeof buf, "0 %u 1\n", uid)) == -1)
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die("failed to write to /proc/self/uid_map");
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close(fd);
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if ((fd = open("/proc/self/setgroups", O_RDWR)) == -1)
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die("failed to open /proc/self/setgroups rw");
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if (write(fd, "deny", 4) == -1)
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die("failed to write to /proc/self/setgroups");
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close(fd);
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if ((fd = open("/proc/self/gid_map", O_RDWR)) == -1)
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die("failed to open /proc/self/gid_map rw");
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if (write(fd, buf, snprintf(buf, sizeof buf, "0 %u 1\n", gid)) == -1)
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die("failed to write to /proc/self/setgroups");
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close(fd);
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/* mount /proc */
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snprintf(mountdir, sizeof(mountdir), "%s/proc", chrootdir);
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if (mount("proc", mountdir, "proc", MS_MGC_VAL|MS_PRIVATE, NULL) == -1)
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die("Failed to mount %s", mountdir);
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/* bind mount /sys */
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bindmount(chrootdir, "/sys", NULL);
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/* bind mount /dev */
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bindmount(chrootdir, "/dev", NULL);
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/* bind mount hostdir if set */
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if (hostdir)
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bindmount(chrootdir, hostdir, "/host");
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/* bind mount distdir (if set) */
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if (distdir)
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bindmount(chrootdir, distdir, "/void-packages");
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/* bind mount shmdir (if set) */
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if (shmdir)
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bindmount(chrootdir, shmdir, NULL);
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/* move chrootdir to / and chroot to it */
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if (chdir(chrootdir) == -1)
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die("chdir to %s", chrootdir);
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if (mount(".", ".", NULL, MS_BIND|MS_PRIVATE, NULL) == -1)
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die("Failed to bind mount %s", chrootdir);
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if (mount(chrootdir, "/", NULL, MS_MOVE, NULL) == -1)
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die("Failed to move %s as rootfs", chrootdir);
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if (chroot(".") == -1)
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die("Failed to chroot to %s", chrootdir);
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if (execvp(cmd, cmdargs) == -1)
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die("Failed to execute command %s", cmd);
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}
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/* Wait until the child terminates */
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while (waitpid(child, &child_status, 0) < 0) {
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if (errno != EINTR)
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die("waitpid");
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}
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if (!WIFEXITED(child_status))
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return -1;
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return WEXITSTATUS(child_status);
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}
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72
bin/xbps-uunshare/xbps-uunshare.8
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72
bin/xbps-uunshare/xbps-uunshare.8
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@ -0,0 +1,72 @@
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.Dd March 5, 2015
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.Dt XBPS-UUNSHARE 8
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.Sh NAME
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.Nm xbps-uunshare
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.Nd XBPS utility to chroot and bind mount with linux user namespaces
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.Sh SYNOPSYS
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.Nm xbps-uunshare
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.Op OPTIONS
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.Ar CHROOTDIR
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.Ar COMMAND
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.Op ARGS
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.Sh DESCRIPTION
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The
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.Nm
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utility allows users to chroot and bind mount required pseudo-filesystems
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(/dev, /proc and /sys) in the target
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.Ar CHROOTDIR
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to execute
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.Ar COMMAND .
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The
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.Nm
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utility uses by default Linux namespaces to isolate IPC, PIDs and mounts to
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the calling process. Thanks to
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.Xr user_namespaces 7
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the user does not need any privilege to create an isolated lightweight container.
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.Sh OPTIONS
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.Bl -tag -width -x
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.It Fl D Ar dir
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Specifies a full path to a directory that will be bind mounted at
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.Ar CHROOTDIR/void-packages .
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.It Fl H Ar dir
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Specifies a full path to a directory that will be bind mounted at
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.Ar CHROOTDIR/host .
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.It Fl S Ar dir
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Specifies a full path to a directory to allow shm functionality to be used
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in the target
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.Ar CHROOTDIR/dir .
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If your system uses
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.Sy /dev/shm
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use it, otherwise use
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.Sy /run/shm .
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.El
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.Sh NOTES
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The
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.Nm
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utility uses Linux specific features (namespaces) and it's not meant to be portable to
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other Operating Systems. The following kernel options must be enabled:
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.Pp
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.Bl -tag -width CONFIG_NAMESPACES -compact -offset indent
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.It Sy CONFIG_NAMESPACES
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.It Sy CONFIG_IPC_NS
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.It Sy CONFIG_PID_NS
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.It Sy CONFIG_USER_NS
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.El
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.Sh SEE ALSO
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.Xr xbps.d 5 ,
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.Xr xbps-checkvers 8 ,
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.Xr xbps-create 8 ,
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.Xr xbps-dgraph 8 ,
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.Xr xbps-install 8 ,
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.Xr xbps-pkgdb 8 ,
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.Xr xbps-query 8 ,
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.Xr xbps-reconfigure 8 ,
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.Xr xbps-rindex 8 ,
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.Xr xbps-uchroot 8
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.Sh AUTHORS
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.An Juan Romero Pardines <xtraeme@gmail.com>
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.Sh BUGS
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Probably, but I try to make this not happen. Use it under your own
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responsability and enjoy your life.
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.Pp
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Report bugs in https://github.com/voidlinux/xbps/issues
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