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/*
* Copyright (C) 2014-2018 Firejail Authors
*
* This file is part of firejail project
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "firejail.h"
#include <sys/mount.h>
#include <sys/stat.h>
#include <linux/limits.h>
#include <glob.h>
#include <dirent.h>
#include <fcntl.h>
void fs_hostname(const char *hostname) {
struct stat s;
// create a new /etc/hostname
if (stat("/etc/hostname", &s) == 0) {
if (arg_debug)
printf("Creating a new /etc/hostname file\n");
create_empty_file_as_root(RUN_HOSTNAME_FILE, S_IRUSR | S_IWRITE | S_IRGRP | S_IROTH);
// bind-mount the file on top of /etc/hostname
if (mount(RUN_HOSTNAME_FILE, "/etc/hostname", NULL, MS_BIND|MS_REC, NULL) < 0)
errExit("mount bind /etc/hostname");
fs_logger("create /etc/hostname");
}
// create a new /etc/hosts
if (cfg.hosts_file == NULL && stat("/etc/hosts", &s) == 0) {
if (arg_debug)
printf("Creating a new /etc/hosts file\n");
// copy /etc/host into our new file, and modify it on the fly
/* coverity[toctou] */
FILE *fp1 = fopen("/etc/hosts", "r");
if (!fp1)
goto errexit;
FILE *fp2 = fopen(RUN_HOSTS_FILE, "w");
if (!fp2) {
fclose(fp1);
goto errexit;
}
char buf[4096];
int done = 0;
while (fgets(buf, sizeof(buf), fp1)) {
// remove '\n'
char *ptr = strchr(buf, '\n');
if (ptr)
*ptr = '\0';
// copy line
if (strstr(buf, "127.0.0.1") && done == 0) {
done = 1;
fprintf(fp2, "%s %s\n", buf, hostname);
}
else
fprintf(fp2, "%s\n", buf);
}
fclose(fp1);
// mode and owner
SET_PERMS_STREAM(fp2, 0, 0, S_IRUSR | S_IWRITE | S_IRGRP | S_IROTH);
fclose(fp2);
// bind-mount the file on top of /etc/hostname
fs_mount_hosts_file();
}
return;
errexit:
fprintf(stderr, "Error: cannot create hostname file\n");
exit(1);
}
void fs_resolvconf(void) {
if (cfg.dns1 == NULL)
return;
if (arg_debug)
printf("mirroring /etc directory\n");
if (mkdir(RUN_DNS_ETC, 0755))
errExit("mkdir");
fs_logger("tmpfs /etc");
DIR *dir = opendir("/etc");
if (!dir)
errExit("opendir");
struct stat s;
struct dirent *entry;
while ((entry = readdir(dir))) {
if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
continue;
// for resolv.conf we create a brand new file
if (strcmp(entry->d_name, "resolv.conf") == 0)
continue;
// printf("linking %s\n", entry->d_name);
char *src;
if (asprintf(&src, "/etc/%s", entry->d_name) == -1)
errExit("asprintf");
if (stat(src, &s) != 0) {
free(src);
continue;
}
char *dest;
if (asprintf(&dest, "%s/%s", RUN_DNS_ETC, entry->d_name) == -1)
errExit("asprintf");
int symlink_done = 0;
if (is_link(src)) {
char *rp =realpath(src, NULL);
if (rp == NULL) {
free(src);
free(dest);
continue;
}
if (symlink(rp, dest))
errExit("symlink");
else
symlink_done = 1;
}
else if (S_ISDIR(s.st_mode))
create_empty_dir_as_root(dest, s.st_mode);
else
create_empty_file_as_root(dest, s.st_mode);
// bind-mount src on top of dest
if (!symlink_done) {
if (mount(src, dest, NULL, MS_BIND|MS_REC, NULL) < 0)
errExit("mount bind mirroring /etc");
}
fs_logger2("clone", src);
free(src);
free(dest);
}
closedir(dir);
// mount bind our private etc directory on top of /etc
if (arg_debug)
printf("Mount-bind %s on top of /etc\n", RUN_DNS_ETC);
if (mount(RUN_DNS_ETC, "/etc", NULL, MS_BIND|MS_REC, NULL) < 0)
errExit("mount bind mirroring /etc");
fs_logger("mount /etc");
if (arg_debug)
printf("Creating a new /etc/resolv.conf file\n");
FILE *fp = fopen("/etc/resolv.conf", "w");
if (!fp) {
fprintf(stderr, "Error: cannot create /etc/resolv.conf file\n");
exit(1);
}
if (cfg.dns1)
fprintf(fp, "nameserver %s\n", cfg.dns1);
if (cfg.dns2)
fprintf(fp, "nameserver %s\n", cfg.dns2);
if (cfg.dns3)
fprintf(fp, "nameserver %s\n", cfg.dns3);
if (cfg.dns4)
fprintf(fp, "nameserver %s\n", cfg.dns4);
// mode and owner
SET_PERMS_STREAM(fp, 0, 0, 0644);
fclose(fp);
fs_logger("create /etc/resolv.conf");
}
char *fs_check_hosts_file(const char *fname) {
assert(fname);
invalid_filename(fname, 0); // no globbing
char *rv = expand_macros(fname);
// no a link
if (is_link(rv))
goto errexit;
// the user has read access to the file
if (access(rv, R_OK))
goto errexit;
return rv;
errexit:
fprintf(stderr, "Error: invalid file %s\n", fname);
exit(1);
}
void fs_store_hosts_file(void) {
copy_file_from_user_to_root(cfg.hosts_file, RUN_HOSTS_FILE, 0, 0, 0644); // root needed
}
void fs_mount_hosts_file(void) {
if (arg_debug)
printf("Loading user hosts file\n");
// check /etc/hosts file
struct stat s;
if (stat("/etc/hosts", &s) == -1)
goto errexit;
// not a link
if (is_link("/etc/hosts"))
goto errexit;
// owned by root
if (s.st_uid != 0)
goto errexit;
// bind-mount the file on top of /etc/hostname
if (mount(RUN_HOSTS_FILE, "/etc/hosts", NULL, MS_BIND|MS_REC, NULL) < 0)
errExit("mount bind /etc/hosts");
fs_logger("create /etc/hosts");
return;
errexit:
fprintf(stderr, "Error: invalid /etc/hosts file\n");
exit(1);
}
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