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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.
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <linux/filter.h>
#define MAXBUF 1024
#define errExit(msg) { char msgout[256]; \
snprintf(msgout, 256, "Error %d: %s", __LINE__, (msg)); \
perror(msgout); \
exit(1); }
// dump all seccomp filters of a process
// for further analysis with fsec-print
// requires kernel 4.4 or higher
void dump_filter(const char *dname, unsigned cnt, const struct sock_filter *f, size_t nmemb) {
char fname[MAXBUF];
snprintf(fname, MAXBUF, "%s/%u", dname, cnt);
printf("Writing file %s\n", fname);
FILE *fp = fopen(fname, "w");
if (!fp) {
printf("Error: Cannot open %s for writing: %s\n", fname, strerror(errno));
exit(1);
}
if (fwrite(f, sizeof(struct sock_filter), nmemb, fp) != nmemb) {
printf("Error: Cannot write %s\n", fname);
exit(1);
}
fclose(fp);
}
int main(int argc, char **argv) {
if (argc != 2)
goto usage;
pid_t pid = (pid_t) strtol(argv[1], NULL, 10);
if (pid <= 0)
goto usage;
printf("** Attaching to process with pid %d **\n", pid);
long rv = ptrace(PTRACE_ATTACH, pid, 0, 0);
if (rv != 0) {
printf("Error: Cannot attach: %s\n", strerror(errno));
exit(1);
}
waitpid(pid, NULL, 0);
printf("Attached\n");
char dname[MAXBUF];
snprintf(dname, MAXBUF, "/tmp/seccomp-%d", pid);
printf("** Creating directory %s **\n", dname);
if (mkdir(dname, 0755) < 0) {
printf("Error: Cannot create directory: %s\n", strerror(errno));
exit(1);
}
printf("Created\n");
printf("** Extracting seccomp filters **\n");
unsigned cnt = 0;
while ((rv = ptrace(PTRACE_SECCOMP_GET_FILTER, pid, cnt, NULL)) > 0) {
struct sock_filter *f = malloc(rv * sizeof(struct sock_filter));
if (!f)
errExit("malloc");
if (ptrace(PTRACE_SECCOMP_GET_FILTER, pid, cnt, f) < 0)
errExit("ptrace");
dump_filter(dname, cnt, f, rv);
free(f);
cnt++;
}
if (cnt)
printf("Dumped %u filters\n", cnt);
else {
printf("No seccomp filter was found\n");
printf("** Cleanup **\n");
if (remove(dname) == 0)
printf("Removed %s\n", dname);
else
printf("Could not remove %s: %s\n", dname, strerror(errno));
}
printf("Bye ...\n");
return 0;
usage:
printf("Usage: %s <PID>\n", argv[0]);
return 1;
}
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