0cddb12ffd
because we need to do ioctl(2)s, which are not permitted in the capability mode. What we do now is to chroot(2) to /var/empty, which restricts access to file system name space and we drop privileges to hast user and hast group. This still allows to access to other name spaces, like list of processes, network and sysvipc. To address that, use jail(2) instead of chroot(2). Using jail(2) will restrict access to process table, network (we use ip-less jails) and sysvipc (if security.jail.sysvipc_allowed is turned off). This provides much better separation. MFC after: 1 week
253 lines
6.6 KiB
C
253 lines
6.6 KiB
C
/*-
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* Copyright (c) 2010 The FreeBSD Foundation
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* Copyright (c) 2011 Pawel Jakub Dawidek <pawel@dawidek.net>
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* All rights reserved.
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*
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* This software was developed by Pawel Jakub Dawidek under sponsorship from
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* the FreeBSD Foundation.
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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 AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/capability.h>
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#include <sys/param.h>
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#include <sys/disk.h>
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#include <sys/ioctl.h>
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#include <sys/jail.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <pwd.h>
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#include <stdarg.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <pjdlog.h>
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#include "hast.h"
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#include "subr.h"
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int
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vsnprlcat(char *str, size_t size, const char *fmt, va_list ap)
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{
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size_t len;
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len = strlen(str);
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return (vsnprintf(str + len, size - len, fmt, ap));
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}
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int
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snprlcat(char *str, size_t size, const char *fmt, ...)
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{
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va_list ap;
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int result;
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va_start(ap, fmt);
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result = vsnprlcat(str, size, fmt, ap);
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va_end(ap);
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return (result);
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}
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int
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provinfo(struct hast_resource *res, bool dowrite)
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{
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struct stat sb;
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PJDLOG_ASSERT(res->hr_localpath != NULL &&
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res->hr_localpath[0] != '\0');
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if (res->hr_localfd == -1) {
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res->hr_localfd = open(res->hr_localpath,
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dowrite ? O_RDWR : O_RDONLY);
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if (res->hr_localfd < 0) {
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KEEP_ERRNO(pjdlog_errno(LOG_ERR, "Unable to open %s",
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res->hr_localpath));
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return (-1);
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}
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}
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if (fstat(res->hr_localfd, &sb) < 0) {
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KEEP_ERRNO(pjdlog_errno(LOG_ERR, "Unable to stat %s",
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res->hr_localpath));
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return (-1);
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}
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if (S_ISCHR(sb.st_mode)) {
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/*
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* If this is character device, it is most likely GEOM provider.
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*/
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if (ioctl(res->hr_localfd, DIOCGMEDIASIZE,
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&res->hr_local_mediasize) < 0) {
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KEEP_ERRNO(pjdlog_errno(LOG_ERR,
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"Unable obtain provider %s mediasize",
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res->hr_localpath));
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return (-1);
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}
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if (ioctl(res->hr_localfd, DIOCGSECTORSIZE,
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&res->hr_local_sectorsize) < 0) {
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KEEP_ERRNO(pjdlog_errno(LOG_ERR,
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"Unable obtain provider %s sectorsize",
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res->hr_localpath));
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return (-1);
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}
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} else if (S_ISREG(sb.st_mode)) {
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/*
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* We also support regular files for which we hardcode
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* sector size of 512 bytes.
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*/
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res->hr_local_mediasize = sb.st_size;
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res->hr_local_sectorsize = 512;
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} else {
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/*
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* We support no other file types.
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*/
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pjdlog_error("%s is neither GEOM provider nor regular file.",
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res->hr_localpath);
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errno = EFTYPE;
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return (-1);
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}
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return (0);
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}
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const char *
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role2str(int role)
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{
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switch (role) {
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case HAST_ROLE_INIT:
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return ("init");
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case HAST_ROLE_PRIMARY:
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return ("primary");
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case HAST_ROLE_SECONDARY:
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return ("secondary");
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}
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return ("unknown");
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}
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int
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drop_privs(struct hast_resource *res)
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{
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char jailhost[sizeof(res->hr_name) * 2];
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struct jail jailst;
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struct passwd *pw;
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uid_t ruid, euid, suid;
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gid_t rgid, egid, sgid;
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gid_t gidset[1];
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bool capsicum, jailed;
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/*
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* According to getpwnam(3) we have to clear errno before calling the
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* function to be able to distinguish between an error and missing
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* entry (with is not treated as error by getpwnam(3)).
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*/
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errno = 0;
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pw = getpwnam(HAST_USER);
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if (pw == NULL) {
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if (errno != 0) {
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KEEP_ERRNO(pjdlog_errno(LOG_ERR,
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"Unable to find info about '%s' user", HAST_USER));
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return (-1);
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} else {
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pjdlog_error("'%s' user doesn't exist.", HAST_USER);
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errno = ENOENT;
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return (-1);
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}
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}
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bzero(&jailst, sizeof(jailst));
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jailst.version = JAIL_API_VERSION;
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jailst.path = pw->pw_dir;
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if (res == NULL) {
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(void)snprintf(jailhost, sizeof(jailhost), "hastctl");
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} else {
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(void)snprintf(jailhost, sizeof(jailhost), "hastd: %s (%s)",
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res->hr_name, role2str(res->hr_role));
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}
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jailst.hostname = jailhost;
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jailst.jailname = NULL;
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jailst.ip4s = 0;
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jailst.ip4 = NULL;
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jailst.ip6s = 0;
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jailst.ip6 = NULL;
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if (jail(&jailst) >= 0) {
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jailed = true;
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} else {
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jailed = false;
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pjdlog_errno(LOG_WARNING,
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"Unable to jail to directory to %s", pw->pw_dir);
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if (chroot(pw->pw_dir) == -1) {
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KEEP_ERRNO(pjdlog_errno(LOG_ERR,
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"Unable to change root directory to %s",
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pw->pw_dir));
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return (-1);
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}
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}
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PJDLOG_VERIFY(chdir("/") == 0);
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gidset[0] = pw->pw_gid;
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if (setgroups(1, gidset) == -1) {
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KEEP_ERRNO(pjdlog_errno(LOG_ERR,
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"Unable to set groups to gid %u",
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(unsigned int)pw->pw_gid));
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return (-1);
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}
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if (setgid(pw->pw_gid) == -1) {
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KEEP_ERRNO(pjdlog_errno(LOG_ERR, "Unable to set gid to %u",
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(unsigned int)pw->pw_gid));
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return (-1);
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}
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if (setuid(pw->pw_uid) == -1) {
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KEEP_ERRNO(pjdlog_errno(LOG_ERR, "Unable to set uid to %u",
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(unsigned int)pw->pw_uid));
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return (-1);
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}
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if (res == NULL || res->hr_role != HAST_ROLE_PRIMARY)
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capsicum = (cap_enter() == 0);
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else
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capsicum = false;
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/*
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* Better be sure that everything succeeded.
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*/
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PJDLOG_VERIFY(getresuid(&ruid, &euid, &suid) == 0);
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PJDLOG_VERIFY(ruid == pw->pw_uid);
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PJDLOG_VERIFY(euid == pw->pw_uid);
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PJDLOG_VERIFY(suid == pw->pw_uid);
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PJDLOG_VERIFY(getresgid(&rgid, &egid, &sgid) == 0);
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PJDLOG_VERIFY(rgid == pw->pw_gid);
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PJDLOG_VERIFY(egid == pw->pw_gid);
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PJDLOG_VERIFY(sgid == pw->pw_gid);
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PJDLOG_VERIFY(getgroups(0, NULL) == 1);
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PJDLOG_VERIFY(getgroups(1, gidset) == 1);
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PJDLOG_VERIFY(gidset[0] == pw->pw_gid);
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pjdlog_debug(1,
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"Privileges successfully dropped using %s%s+setgid+setuid.",
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capsicum ? "capsicum+" : "", jailed ? "jail" : "chroot");
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return (0);
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}
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