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// SPDX-License-Identifier: AGPL-3.0-or-later
/* SEITAN - Syscall Expressive Interpreter, Transformer and Notifier
*
* eater.c - Load BPF program and execute binary
*
* Copyright (c) 2022 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*/
#define _GNU_SOURCE
#include <errno.h>
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <argp.h>
#include <sys/prctl.h>
#include <sys/syscall.h>
#include <sys/socket.h>
#include <signal.h>
#include <linux/audit.h>
#include <linux/filter.h>
#include <linux/seccomp.h>
extern char **environ;
static char doc[] =
"Usage: seitan-eater: setain-eater -i <input file> -- program args1 args2...";
/* Eater options */
static struct argp_option options[] = { { "input", 'i', "FILE", 0,
"BPF filter input file", 0 },
{ 0 } };
struct arguments {
char *input_file;
unsigned int program_index;
};
static error_t parse_opt(int key, char *arg, struct argp_state *state)
{
struct arguments *arguments = state->input;
if (state->quoted == 0)
arguments->program_index = state->next + 1;
switch (key) {
case 'i':
if (state->quoted == 0)
arguments->input_file = arg;
break;
case ARGP_KEY_END:
if (arguments->input_file == NULL)
argp_error(state, "missing input file");
if (state->argv[arguments->program_index] == NULL)
argp_error(state, "missing program");
break;
}
return 0;
}
static struct argp argp = { .options = options,
.parser = parse_opt,
.args_doc = NULL,
.doc = doc,
.children = NULL,
.help_filter = NULL,
.argp_domain = NULL };
static int seccomp(unsigned int operation, unsigned int flags, void *args)
{
return syscall(__NR_seccomp, operation, flags, args);
}
static void signal_handler(__attribute__((unused))int s){}
/**
* main() - Entry point
* @argc: Argument count
* @argv: Seitan-eater and program arguments
*
* Return: 0 once interrupted, non-zero on failure
*/
int main(int argc, char **argv)
{
struct sock_filter filter[1024];
struct arguments arguments;
struct sock_fprog prog;
struct sigaction act;
size_t n;
int fd;
argp_parse(&argp, argc, argv, 0, 0, &arguments);
fd = open(arguments.input_file, O_CLOEXEC | O_RDONLY);
n = read(fd, filter, sizeof(filter));
close(fd);
prog.filter = filter;
prog.len = (unsigned short)(n / sizeof(filter[0]));
if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) != 0) {
perror("prctl");
exit(EXIT_FAILURE);
}
if ((fd = seccomp(SECCOMP_SET_MODE_FILTER, SECCOMP_FILTER_FLAG_NEW_LISTENER,
&prog) < 0)) {
perror("seccomp");
exit(EXIT_FAILURE);
}
act.sa_handler = signal_handler;
sigaction(SIGCONT, &act, NULL);
pause();
execvpe(argv[arguments.program_index], &argv[arguments.program_index],
environ);
if (errno != ENOENT) {
perror("execvpe");
exit(EXIT_FAILURE);
}
return EXIT_FAILURE;
}
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