seccomp_syscall_priority(3) — Linux manual page


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 SCMP_SYS() macro returns a value suitable for use as the syscall
       value in seccomp_syscall_priority().

       The seccomp_syscall_priority() function returns zero on success or
       one of the following error codes on failure:

       -EDOM  Architecture specific failure.

              Internal libseccomp failure.

              Invalid input, either the context or architecture token is

              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_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 2020-09-18.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-09-15.)  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              30 May 2020     seccomp_syscall_priority(3)

Pages that refer to this page: seccomp_attr_get(3)seccomp_attr_set(3)seccomp_rule_add(3)seccomp_rule_add_array(3)seccomp_rule_add_exact(3)seccomp_rule_add_exact_array(3)