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/*
* Copyright (C) 2014-2016 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 "fseccomp.h"
#include "../include/seccomp.h"
#include <sys/syscall.h>
static struct sock_filter *filter = NULL;
static int filter_cnt = 0;
static void load_seccomp(const char *fname) {
assert(fname);
// open filter file
int fd = open(fname, O_RDONLY);
if (fd == -1)
goto errexit;
// calculate the number of entries
int size = lseek(fd, 0, SEEK_END);
if (size == -1)
goto errexit;
if (lseek(fd, 0 , SEEK_SET) == -1)
goto errexit;
unsigned short entries = (unsigned short) size / (unsigned short) sizeof(struct sock_filter);
filter_cnt = entries;
// read filter
filter = malloc(size);
if (filter == NULL)
goto errexit;
memset(filter, 0, size);
int rd = 0;
while (rd < size) {
int rv = read(fd, (unsigned char *) filter + rd, size - rd);
if (rv == -1)
goto errexit;
rd += rv;
}
// close file
close(fd);
return;
errexit:
fprintf(stderr, "Error fseccomp: cannot read %s\n", fname);
exit(1);
}
// debug filter
void filter_print(const char *fname) {
assert(fname);
load_seccomp(fname);
// start filter
struct sock_filter start[] = {
VALIDATE_ARCHITECTURE,
EXAMINE_SYSCALL
};
// print sizes
printf("SECCOMP Filter:\n");
// test the start of the filter
if (memcmp(&start[0], filter, sizeof(start)) == 0) {
printf(" VALIDATE_ARCHITECTURE\n");
printf(" EXAMINE_SYSCAL\n");
}
else {
printf("Invalid seccomp filter %s\n", fname);
return;
}
// loop trough blacklists
int i = 4;
while (i < filter_cnt) {
// minimal parsing!
unsigned char *ptr = (unsigned char *) &filter[i];
int *nr = (int *) (ptr + 4);
if (*ptr == 0x15 && *(ptr +14) == 0xff && *(ptr + 15) == 0x7f ) {
printf(" WHITELIST %d %s\n", *nr, syscall_find_nr(*nr));
i += 2;
}
else if (*ptr == 0x15 && *(ptr +14) == 0 && *(ptr + 15) == 0) {
printf(" BLACKLIST %d %s\n", *nr, syscall_find_nr(*nr));
i += 2;
}
else if (*ptr == 0x15 && *(ptr +14) == 0x5 && *(ptr + 15) == 0) {
int err = *(ptr + 13) << 8 | *(ptr + 12);
printf(" ERRNO %d %s %d %s\n", *nr, syscall_find_nr(*nr), err, errno_find_nr(err));
i += 2;
}
else if (*ptr == 0x06 && *(ptr +6) == 0 && *(ptr + 7) == 0 ) {
printf(" KILL_PROCESS\n");
i++;
}
else if (*ptr == 0x06 && *(ptr +6) == 0xff && *(ptr + 7) == 0x7f ) {
printf(" RETURN_ALLOW\n");
i++;
}
else {
printf(" UNKNOWN ENTRY!!!\n");
i++;
}
}
}
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