seccomp_syscall_priority(3)ibseccomp Documentationeccomp_syscall_priority(3)

NAME         top

       seccomp_syscall_priority - Prioritize syscalls in the seccomp filter

SYNOPSIS         top

       #include <seccomp.h>

       typedef void * scmp_filter_ctx;

       int SCMP_SYS(syscall_name);

       int seccomp_syscall_priority(scmp_filter_ctx ctx,
                                    int syscall, uint8_t priority);

       Link with -lseccomp.

DESCRIPTION         top

       The seccomp_syscall_priority() function provides a priority hint to
       the seccomp filter generator in libseccomp such that higher priority
       syscalls are placed earlier in the seccomp filter code so that they
       incur less overhead at the expense of lower priority syscalls.  A
       syscall's priority can be set regardless of if any rules currently
       exist for that syscall; the library will remember the priority and it
       will be assigned to the syscall if and when a rule for that syscall
       is created.

       While it is possible to specify the syscall value directly using the
       standard __NR_syscall values, in order to ensure proper operation
       across multiple architectures it is highly recommended to use the
       SCMP_SYS() macro instead.  See the EXAMPLES section below.

       The priority parameter takes an 8-bit value ranging from 0 - 255; a
       higher value represents a higher priority.

       The filter context ctx is the value returned by the call to

RETURN VALUE         top

       The seccomp_syscall_priority() function returns zero on success,
       negative errno values on failure.  The SCMP_SYS() macro returns a
       value suitable for use as the syscall value in

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_syscall_priority(ctx, SCMP_SYS(read), 200);
            if (rc < 0)
                 goto out;

            /* ... */

            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  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 <>

SEE ALSO         top

       seccomp_rule_add(3), seccomp_rule_add_exact(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 ⟨⟩.  If you have a
       bug report for this manual page, see 
       ⟨⟩.  This page was
       obtained from the project's upstream Git repository 
       ⟨⟩ on 2017-03-13.  If you dis‐
       cover 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             25 July 2012     seccomp_syscall_priority(3)