seccomp_syscall_priority - Prioritize syscalls in the seccomp filter
#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.
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().
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.
- -EFAULT
- Internal libseccomp failure.
- -EINVAL
- Invalid input, either the context or architecture token is
invalid.
- -ENOMEM
- The library was unable to allocate enough memory.
#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;
}
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.
Paul Moore <
[email protected]>
seccomp_rule_add(3),
seccomp_rule_add_exact(3)