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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 "jailtest.h"
#include <sys/wait.h>
#include <sys/stat.h>
#include <fcntl.h>
static unsigned char *execfile = NULL;
static int execfile_len = 0;
void noexec_setup(void) {
// grab a copy of myself
char *self = realpath("/proc/self/exe", NULL);
if (self) {
struct stat s;
if (access(self, X_OK) == 0 && stat(self, &s) == 0) {
assert(s.st_size);
execfile = malloc(s.st_size);
int fd = open(self, O_RDONLY);
if (fd == -1)
errExit("open");
int len = 0;
do {
int rv = read(fd, execfile + len, s.st_size - len);
if (rv == -1)
errExit("read");
if (rv == 0) {
// something went wrong!
free(execfile);
execfile = NULL;
printf("Warning: I cannot grab a copy of myself, skipping noexec test...\n");
break;
}
len += rv;
}
while (len < s.st_size);
execfile_len = s.st_size;
close(fd);
}
}
}
void noexec_test(const char *path) {
assert(user_uid);
// I am root in sandbox mount namespace
if (!execfile)
return;
char *fname;
if (asprintf(&fname, "%s/jailtest-noexec-%d", path, getpid()) == -1)
errExit("asprintf");
pid_t child = fork();
if (child == -1)
errExit("fork");
if (child == 0) { // child
// drop privileges
if (setgid(user_gid) != 0)
errExit("setgid");
if (setuid(user_uid) != 0)
errExit("setuid");
int fd = open(fname, O_CREAT | O_TRUNC | O_WRONLY, 0700);
if (fd == -1) {
printf(" I cannot create files in %s, skipping noexec...\n", path);
exit(1);
}
int len = 0;
while (len < execfile_len) {
int rv = write(fd, execfile + len, execfile_len - len);
if (rv == -1 || rv == 0) {
printf(" I cannot create files in %s, skipping noexec....\n", path);
exit(1);
}
len += rv;
}
fchmod(fd, 0700);
close(fd);
char *arg;
if (asprintf(&arg, "--hello=%s", path) == -1)
errExit("asprintf");
int rv = execl(fname, fname, arg, NULL);
(void) rv; // if we get here execl failed
exit(0);
}
int status;
wait(&status);
int rv = unlink(fname);
(void) rv;
}
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