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/*
* Copyright (C) 2014-2020 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 "../include/seccomp.h"
#include "../include/rundefs.h"
#include <fcntl.h>
#include <linux/filter.h>
#include <sys/mman.h>
#include <sys/prctl.h>
#include <unistd.h>
#include <stdio.h>
__attribute__((constructor))
static void load_seccomp(void) {
int fd = open(RUN_SECCOMP_POSTEXEC, O_RDONLY);
if (fd == -1) {
fprintf(stderr, "Error: cannot open seccomp postexec filter file %s\n", RUN_SECCOMP_POSTEXEC);
return;
}
off_t size = lseek(fd, 0, SEEK_END);
if (size <= 0) {
close(fd);
return;
}
unsigned short entries = (unsigned short) size / (unsigned short) sizeof(struct sock_filter);
struct sock_filter *filter = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
if (filter == MAP_FAILED) {
fprintf(stderr, "Error: cannot map seccomp postexec filter data\n");
return;
}
// install filter
struct sock_fprog prog = {
.len = entries,
.filter = filter,
};
prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
munmap(filter, size);
}
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