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/*
* The approach described below does not actually work. Apparantly,
* SELinux will assign a context based upond the underlying policy
* (typically from a fs_use statement); the operating system will not
* invoke this file's fuse_getxattr() function at all. Thus it is
* not possible to use FUSE to create a virtual filesystem with
* arbitrary file contexts.
*/
/**
* @file
*
* Use the FUSE (filesystem in userspace) to create a virtual
* filesystem for libsefs tests. This particular filesystem will not
* contain MLS contexts.
*
* @author Jeremy A. Mowery jmowery@tresys.com
* @author Jason Tang jtang@tresys.com
*
* Copyright (C) 2007 Tresys Technology, LLC
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <config.h>
#define FUSE_USE_VERSION 25
#define XATTR_NAME_SELINUX "security.selinux"
#include <apol/bst.h>
#include <fuse.h>
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
/*************** definition of the virtual filesystem ***************/
static apol_bst_t *bst = NULL;
struct fuse_entry
{
const char *path;
mode_t mode;
const char *context;
};
static struct fuse_entry fs[] = {
{"/", S_IFDIR, "user_r:object_r:system_t"},
{"/foo", S_IFREG, "user_r:object_r:system_t"},
{NULL, 0, NULL}
};
static int fuse_comp(const void *a, const void *b, void *data __attribute__ ((unused)))
{
const struct fuse_entry *f1 = (const struct fuse_entry *)a;
const struct fuse_entry *f2 = (const struct fuse_entry *)b;
return strcmp(f1->path, f2->path);
}
/*************** required fuse functions ***************/
static int fuse_getattr(const char *path, struct stat *stbuf)
{
struct fuse_entry key = { path, 0, NULL };
struct fuse_entry *e;
memset(stbuf, 0, sizeof(*stbuf));
if (apol_bst_get_element(bst, &key, NULL, (void **)&e) < 0) {
return -ENOENT;
}
if (e->mode == S_IFDIR) {
stbuf->st_mode = S_IFDIR | 0755;
stbuf->st_nlink = 2;
} else {
stbuf->st_mode = e->mode | 0444;
stbuf->st_nlink = 1;
}
return 0;
}
static int fuse_getxattr(const char *path, const char *attrib_name, char *buf, size_t buflen)
{
struct fuse_entry key = { path, 0, NULL };
struct fuse_entry *e;
if (apol_bst_get_element(bst, &key, NULL, (void **)&e) < 0) {
return -ENOENT;
}
if (strcmp(attrib_name, XATTR_NAME_SELINUX) != 0) {
return -ENOSYS;
}
strncpy(buf, e->context, buflen);
return strlen(e->context) + 1;
}
static int fuse_open(const char *path, struct fuse_file_info *fi __attribute__ ((unused)))
{
struct fuse_entry key = { path, 0, NULL };
struct fuse_entry *e;
if (apol_bst_get_element(bst, &key, NULL, (void **)&e) < 0) {
return -ENOENT;
}
return -EACCES;
}
static int fuse_read(const char *path, char *buf __attribute__ ((unused)), size_t size, off_t offset __attribute__ ((unused)),
struct fuse_file_info *fi __attribute__ ((unused)))
{
struct fuse_entry key = { path, 0, NULL };
struct fuse_entry *e;
if (apol_bst_get_element(bst, &key, NULL, (void **)&e) < 0) {
return -ENOENT;
}
return size;
}
struct stem_data
{
const char *stem;
void *buf;
fuse_fill_dir_t filler;
};
static int fuse_stem_match(void *a, void *data)
{
const struct fuse_entry *e = (const struct fuse_entry *)a;
struct stem_data *sd = (struct stem_data *)data;
size_t e_len = strlen(e->path);
size_t stem_len = strlen(sd->stem);
if (e_len <= stem_len) {
/* entry's path is too longer than the requested path */
return 0;
}
if (strncmp(e->path, sd->stem, stem_len) != 0) {
/* stem is not the beginning of entry's path */
return 0;
}
const char *file = e->path + 1;
if (strchr(file, '/') != NULL) {
/* member of a subdirectory of stem */
return 0;
}
return -sd->filler(sd->buf, file, NULL, 0);
}
static int fuse_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
off_t offset __attribute__ ((unused)), struct fuse_file_info *fi __attribute__ ((unused)))
{
struct fuse_entry key = { path, 0, NULL };
struct fuse_entry *e;
if (apol_bst_get_element(bst, &key, NULL, (void **)&e) < 0) {
return -ENOENT;
}
filler(buf, ".", NULL, 0);
filler(buf, "..", NULL, 0);
struct stem_data sd = { path, buf, filler };
return -apol_bst_inorder_map(bst, fuse_stem_match, &sd);
}
int main(int argc, char *argv[])
{
if ((bst = apol_bst_create(fuse_comp, NULL)) < 0) {
return 1;
}
for (size_t i = 0; fs[i].path != NULL; i++) {
if (apol_bst_insert(bst, &fs[i], NULL) < 0) {
return 1;
}
}
struct fuse_operations non_mls_oper = {
.getattr = fuse_getattr,
.getxattr = fuse_getxattr,
.open = fuse_open,
.read = fuse_read,
.readdir = fuse_readdir,
};
return fuse_main(argc, argv, &non_mls_oper);
}
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