seccomp/libseccomp_demo.c

This is seccomp/libseccomp_demo.c, an example to accompany the book, The Linux Programming Interface.

This file is not printed in the book; it demonstrates Linux features that are not described in the book (typically features that have appeared since the book was published).

The source code file is copyright 2010, Michael Kerrisk, and is licensed under the GNU General Public License, version 3.

In the listing below, the names of Linux system calls and C library functions are hyperlinked to manual pages from the Linux man-pages project, and the names of functions implemented in the book are hyperlinked to the implementations of those functions.

  Cover of The Linux Programming Interface
/* libseccomp_demo.c
*/
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <seccomp.h>
#include "tlpi_hdr.h"

int main(int argc, char *argv[])
{
    int rc;
    scmp_filter_ctx ctx;

    /* Create seccomp filter state that allows by default */

    ctx = seccomp_init(SCMP_ACT_ALLOW);
    if (ctx == NULL)
        fatal("seccomp_init() failed");

    /* Cause clone() and fork() to fail, each with different errors */

    rc = seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EPERM), SCMP_SYS(clone), 0);
    if (rc < 0)
        errExitEN(-rc, "seccomp_rule_add");

    rc = seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ENOTSUP), SCMP_SYS(fork), 0);
    if (rc < 0)
        errExitEN(-rc, "seccomp_rule_add");

    /* Export the pseudofilter code and BPF binary code,
       each to different file descriptors (if they are open) */

    seccomp_export_pfc(ctx, 5);
    seccomp_export_bpf(ctx, 6);

    /* Install the seccomp filter into the kernel */

    rc = seccomp_load(ctx);
    if (rc < 0)
        errExitEN(-rc, "seccomp_load");

    /* Free the user-space seccomp filter state */

    seccomp_release(ctx);

    if (fork() != -1)
        fprintf(stderr, "fork() succeeded?!\n");
    else
        perror("fork");

    exit(EXIT_SUCCESS);
}

 

Download seccomp/libseccomp_demo.c

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