NAME¶
seccomp_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
seccomp_init().
RETURN VALUE¶
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
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 generated 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 ALSO¶
seccomp_rule_add(3),
seccomp_rule_add_exact(3)