seccomp_arch_add (3)

#include <seccomp.h>

typedef void * scmp_filter_ctx;

#define SCMP_ARCH_NATIVE
#define SCMP_ARCH_X86
#define SCMP_ARCH_X86_64

uint32_t seccomp_arch_native();
int seccomp_arch_exist(const scmp_filter_ctx ctx, uint32_t arch_token);
int seccomp_arch_add(scmp_filter_ctx ctx, uint32_t arch_token);
int seccomp_arch_remove(scmp_filter_ctx ctx, uint32_t arch_token);

Link with -lseccomp.

The seccomp_arch_exist() function tests to see if a given architecture has been added to the seccomp filter in ctx , where the seccomp_arch_add() and seccomp_arch_remove() add and remove, respectively, architectures from the seccomp filter. In all three functions, the architecture values given in arch_token should be the SCMP_ARCH_* defined constants; with the SCMP_ARCH_NATIVE constant always referring to the native compiled architecture. The seccomp_arch_native() function returns the system's architecture such that it will match one of the SCMP_ARCH_* constants.

When a seccomp filter is initialized with the call to seccomp_init(3) the native architecture is automatically added to the filter. If you want to remove the native architecture from the filter, you first need to add another architecture to the filter as a seccomp filter must contain at least one architecture at all times. After you have added a second architecture to the seccomp filter, you can remove the native architecture.

When adding a new architecture to an existing filter, the existing rules will not be added to the new architecture. However, rules added after adding the new architecture will be added to all of the architectures in the filter.

The seccomp_arch_add() and seccomp_arch_remove() functions return zero on success, negative errno values on failure. The seccomp_arch_exist() function returns zero if the architecture exists, -EEXIST if it does not, and other negative errno values on failure.

#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;

	if (seccomp_arch_exist(ctx, SCMP_ARCH_X86) == -EEXIST) {
		rc = seccomp_arch_add(ctx, SCMP_ARCH_X86);
		if (rc != 0)
			goto out_all;
		rc = seccomp_arch_remove(ctx, SCMP_ARCH_NATIVE);
		if (rc != 0)
			goto out_all;
	}

	/* ... */

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 http://libseccomp.sf.net. This library is currently under development, please report any bugs at the project site or directly to the author.

Paul Moore <[email protected]>

seccomp_init(3), seccomp_reset(3), seccom_merge(3)