seccomp_syscall_priority(3)libseccomp Documentationseccomp_syscall_priority(3)NAMEseccomp_syscall_priority - Prioritize syscalls in the seccomp filter
SYNOPSIS
#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
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 sec‐
comp_init().
RETURN VALUE
The seccomp_syscall_priority() function returns zero on success, nega‐
tive errno values on failure. The SCMP_SYS() macro returns a value
suitable for use as the syscall value in seccomp_syscall_priority().
EXAMPLES
#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;
/* ... */
out:
seccomp_release(ctx);
return -rc;
}
NOTES
While the seccomp filter can be generated independent of the kernel,
kernel support is required to load and enforce the seccomp filter gen‐
erated by libseccomp.
The libseccomp project site, with more information and the source code
repository, can be found at http://libseccomp.sf.net. This library is
currently under development, please report any bugs at the project site
or directly to the author.
AUTHOR
Paul Moore <paul@paul-moore.com>
SEE ALSOseccomp_rule_add(3), seccomp_rule_add_exact(3)paul@paul-moore.com 25 July 2012 seccomp_syscall_priority(3)
