src/compute_av.c

#include <unistd.h>
#include <sys/types.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <limits.h>
#include "selinux_internal.h"
#include "policy.h"
#include "mapping.h"

int security_compute_av(const security_context_t scon,
			const security_context_t tcon,
			security_class_t tclass,
			access_vector_t requested,
			struct av_decision *avd)
{
	char path[PATH_MAX];
	char *buf;
	size_t len;
	int fd, ret;

	if (!selinux_mnt) {
		errno = ENOENT;
		return -1;
	}

	snprintf(path, sizeof path, "%s/access", selinux_mnt);
	fd = open(path, O_RDWR);
	if (fd < 0)
		return -1;

	len = selinux_page_size;
	buf = malloc(len);
	if (!buf) {
		ret = -1;
		goto out;
	}

	snprintf(buf, len, "%s %s %hu %x", scon, tcon,
		 unmap_class(tclass), unmap_perm(tclass, requested));

	ret = write(fd, buf, strlen(buf));
	if (ret < 0)
		goto out2;

	memset(buf, 0, len);
	ret = read(fd, buf, len - 1);
	if (ret < 0)
		goto out2;

	ret = sscanf(buf, "%x %x %x %x %u %x",
		     &avd->allowed, &avd->decided,
		     &avd->auditallow, &avd->auditdeny,
		     &avd->seqno, &avd->flags);
	if (ret < 5) {
		ret = -1;
		goto out2;
	} else if (ret < 6)
		avd->flags = 0;

	map_decision(tclass, avd);

	ret = 0;
      out2:
	free(buf);
      out:
	close(fd);
	return ret;
}