seccomp_init(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | EXAMPLES | NOTES | AUTHOR | SEE ALSO | COLOPHON

seccomp_init(3)         libseccomp Documentation         seccomp_init(3)

NAME         top

       seccomp_init, seccomp_reset - Initialize the seccomp filter state

SYNOPSIS         top

       #include <seccomp.h>

       typedef void * scmp_filter_ctx;

       scmp_filter_ctx seccomp_init(uint32_t def_action);
       int seccomp_reset(scmp_filter_ctx ctx, uint32_t def_action);

       Link with -lseccomp.

DESCRIPTION         top

       The seccomp_init() and seccomp_reset() functions (re)initialize
       the internal seccomp filter state, prepares it for use, and sets
       the default action based on the def_action parameter.  The
       seccomp_init() function must be called before any other
       libseccomp functions as the rest of the library API will fail if
       the filter context is not initialized properly.  The
       seccomp_reset() function releases the existing filter context
       state before reinitializing it and can only be called after a
       call to seccomp_init() has succeeded.  If seccomp_reset() is
       called with a NULL filter, it resets the library's global task
       state, including any notification file descriptors retrieved by
       seccomp_notify_fd(3).  Normally this is not needed, but it may be
       required to continue using the library after a fork() or clone()
       call to ensure the API level and user notification state is
       properly reset.

       When the caller is finished configuring the seccomp filter and
       has loaded it into the kernel, the caller should call
       seccomp_release(3) to release all of the filter context state.

       Valid def_action values are as follows:

       SCMP_ACT_KILL
              The thread will be terminated by the kernel with SIGSYS
              when it calls a syscall that does not match any of the
              configured seccomp filter rules.  The thread will not be
              able to catch the signal.

       SCMP_ACT_KILL_PROCESS
              The entire process will be terminated by the kernel with
              SIGSYS when it calls a syscall that does not match any of
              the configured seccomp filter rules.

       SCMP_ACT_TRAP
              The thread will be sent a SIGSYS signal when it calls a
              syscall that does not match any of the configured seccomp
              filter rules.  It may catch this and change its behavior
              accordingly.  When using SA_SIGINFO with sigaction(2),
              si_code will be set to SYS_SECCOMP, si_syscall will be set
              to the syscall that failed the rules, and si_arch will be
              set to the AUDIT_ARCH for the active ABI.

       SCMP_ACT_ERRNO(uint16_t errno)
              The thread will receive a return value of errno when it
              calls a syscall that does not match any of the configured
              seccomp filter rules.

       SCMP_ACT_TRACE(uint16_t msg_num)
              If the thread is being traced and the tracing process
              specified the PTRACE_O_TRACESECCOMP option in the call to
              ptrace(2), the tracing process will be notified, via
              PTRACE_EVENT_SECCOMP, and the value provided in msg_num
              can be retrieved using the PTRACE_GETEVENTMSG option.

       SCMP_ACT_LOG
              The seccomp filter will have no effect on the thread
              calling the syscall if it does not match any of the
              configured seccomp filter rules but the syscall will be
              logged.

       SCMP_ACT_ALLOW
              The seccomp filter will have no effect on the thread
              calling the syscall if it does not match any of the
              configured seccomp filter rules.

RETURN VALUE         top

       The seccomp_init() function returns a filter context on success,
       NULL on failure.  The seccomp_reset() function returns zero on
       success or one of the following error codes on failure:

       -EINVAL
              Invalid input, either the context or action is invalid.

       -ENOMEM
              The library was unable to allocate enough memory.

EXAMPLES         top

       #include <seccomp.h>

       int main(int argc, char *argv[])
       {
            int rc = -1;
            scmp_filter_ctx ctx;

            ctx = seccomp_init(SCMP_ACT_KILL);
            if (ctx == NULL)
                 goto out;

            /* ... */

            rc = seccomp_reset(ctx, SCMP_ACT_KILL);
            if (rc < 0)
                 goto out;

            /* ... */

       out:
            seccomp_release(ctx);
            return -rc;
       }

NOTES         top

       While the seccomp filter can be generated independent of the
       kernel, kernel support is required to load and enforce the
       seccomp filter generated by libseccomp.

       The libseccomp project site, with more information and the source
       code repository, can be found at
       https://github.com/seccomp/libseccomp.  This tool, as well as the
       libseccomp library, is currently under development, please report
       any bugs at the project site or directly to the author.

AUTHOR         top

       Paul Moore <paul@paul-moore.com>

SEE ALSO         top

       seccomp_release(3)

COLOPHON         top

       This page is part of the libseccomp (high-level API to the Linux
       Kernel's seccomp filter) project.  Information about the project
       can be found at ⟨https://github.com/seccomp/libseccomp⟩.  If you
       have a bug report for this manual page, see
       ⟨https://groups.google.com/d/forum/libseccomp⟩.  This page was
       obtained from the project's upstream Git repository
       ⟨https://github.com/seccomp/libseccomp⟩ on 2021-06-20.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-04-28.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

paul@paul-moore.com            30 May 2020               seccomp_init(3)

Pages that refer to this page: seccomp(2)seccomp_arch_add(3)seccomp_attr_set(3)seccomp_export_bpf(3)seccomp_load(3)seccomp_merge(3)seccomp_release(3)seccomp_rule_add(3)