linux/security/apparmor/path.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * AppArmor security module
 *
 * This file contains AppArmor function for pathnames
 *
 * Copyright (C) 1998-2008 Novell/SUSE
 * Copyright 2009-2010 Canonical Ltd.
 */

#include <linux/magic.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/nsproxy.h>
#include <linux/path.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/fs_struct.h>

#include "include/apparmor.h"
#include "include/path.h"
#include "include/policy.h"

/* modified from dcache.c */
static int prepend(char **buffer, int buflen, const char *str, int namelen)
{ … }

#define CHROOT_NSCONNECT …

/* If the path is not connected to the expected root,
 * check if it is a sysctl and handle specially else remove any
 * leading / that __d_path may have returned.
 * Unless
 *     specifically directed to connect the path,
 * OR
 *     if in a chroot and doing chroot relative paths and the path
 *     resolves to the namespace root (would be connected outside
 *     of chroot) and specifically directed to connect paths to
 *     namespace root.
 */
static int disconnect(const struct path *path, char *buf, char **name,
		      int flags, const char *disconnected)
{ … }

/**
 * d_namespace_path - lookup a name associated with a given path
 * @path: path to lookup  (NOT NULL)
 * @buf:  buffer to store path to  (NOT NULL)
 * @name: Returns - pointer for start of path name with in @buf (NOT NULL)
 * @flags: flags controlling path lookup
 * @disconnected: string to prefix to disconnected paths
 *
 * Handle path name lookup.
 *
 * Returns: %0 else error code if path lookup fails
 *          When no error the path name is returned in @name which points to
 *          a position in @buf
 */
static int d_namespace_path(const struct path *path, char *buf, char **name,
			    int flags, const char *disconnected)
{ … }

/**
 * aa_path_name - get the pathname to a buffer ensure dir / is appended
 * @path: path the file  (NOT NULL)
 * @flags: flags controlling path name generation
 * @buffer: buffer to put name in (NOT NULL)
 * @name: Returns - the generated path name if !error (NOT NULL)
 * @info: Returns - information on why the path lookup failed (MAYBE NULL)
 * @disconnected: string to prepend to disconnected paths
 *
 * @name is a pointer to the beginning of the pathname (which usually differs
 * from the beginning of the buffer), or NULL.  If there is an error @name
 * may contain a partial or invalid name that can be used for audit purposes,
 * but it can not be used for mediation.
 *
 * We need PATH_IS_DIR to indicate whether the file is a directory or not
 * because the file may not yet exist, and so we cannot check the inode's
 * file type.
 *
 * Returns: %0 else error code if could retrieve name
 */
int aa_path_name(const struct path *path, int flags, char *buffer,
		 const char **name, const char **info, const char *disconnected)
{ … }