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/*
* Copyright (C) 2014-2021 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>
#include <pwd.h>
// create an empty /etc/ld.so.preload
void fs_trace_touch_preload(void) {
create_empty_file_as_root("/etc/ld.so.preload", S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
}
void fs_trace_touch_or_store_preload(void) {
struct stat s;
if (stat("/etc/ld.so.preload", &s) != 0) {
fs_trace_touch_preload();
return;
}
if (s.st_size == 0)
return;
// create a copy of /etc/ld.so.preload
if (copy_file("/etc/ld.so.preload", RUN_LDPRELOAD_FILE, 0, 0, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)) {
fprintf(stderr, "Error: cannot copy /etc/ld.so.preload file\n");
exit(1);
}
}
void fs_tracefile(void) {
// create a bind mounted trace logfile that the sandbox can see
if (arg_debug)
printf("Creating an empty trace log file: %s\n", arg_tracefile);
EUID_USER();
int fd = open(arg_tracefile, O_CREAT|O_WRONLY|O_CLOEXEC, S_IRUSR | S_IWRITE | S_IRGRP | S_IROTH);
if (fd == -1) {
perror("open");
fprintf(stderr, "Error: cannot open trace log file %s for writing\n", arg_tracefile);
exit(1);
}
struct stat s;
if (fstat(fd, &s) == -1)
errExit("fstat");
if (!S_ISREG(s.st_mode)) {
fprintf(stderr, "Error: cannot write trace log: %s is no regular file\n", arg_tracefile);
exit(1);
}
if (ftruncate(fd, 0) == -1)
errExit("ftruncate");
EUID_ROOT();
FILE *fp = fopen(RUN_TRACE_FILE, "we");
if (!fp)
errExit("fopen " RUN_TRACE_FILE);
fclose(fp);
fs_logger2("touch", arg_tracefile);
// mount using the symbolic link in /proc/self/fd
if (arg_debug)
printf("Bind mount %s to %s\n", arg_tracefile, RUN_TRACE_FILE);
if (bind_mount_fd_to_path(fd, RUN_TRACE_FILE))
errExit("mount bind " RUN_TRACE_FILE);
close(fd);
// now that RUN_TRACE_FILE is user-writable, mount it noexec
fs_remount(RUN_TRACE_FILE, MOUNT_NOEXEC, 0);
}
void fs_trace(void) {
// create the new ld.so.preload file and mount-bind it
if (arg_debug)
printf("Create the new ld.so.preload file\n");
FILE *fp = fopen(RUN_LDPRELOAD_FILE, "ae");
if (!fp)
errExit("fopen");
const char *prefix = RUN_FIREJAIL_LIB_DIR;
if (arg_trace) {
fprintf(fp, "%s/libtrace.so\n", prefix);
}
else if (arg_tracelog) {
fprintf(fp, "%s/libtracelog.so\n", prefix);
fmessage("Blacklist violations are logged to syslog\n");
}
if (arg_seccomp_postexec) {
fprintf(fp, "%s/libpostexecseccomp.so\n", prefix);
fmessage("Post-exec seccomp protector enabled\n");
}
SET_PERMS_STREAM(fp, 0, 0, S_IRUSR | S_IWRITE | S_IRGRP | S_IROTH);
fclose(fp);
// mount the new preload file
if (arg_debug)
printf("Mount the new ld.so.preload file\n");
if (mount(RUN_LDPRELOAD_FILE, "/etc/ld.so.preload", NULL, MS_BIND|MS_REC, NULL) < 0)
errExit("mount bind ld.so.preload");
fs_logger("create /etc/ld.so.preload");
}
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