/* * AppArmor security module * * This file contains AppArmor function for pathnames * * Copyright (C) 1998-2008 Novell/SUSE * Copyright 2009-2010 Canonical Ltd. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation, version 2 of the * License. */ #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){	buflen -= namelen;	if (buflen < 0)		return -ENAMETOOLONG;	*buffer -= namelen;	memcpy(*buffer, str, namelen);	return 0;} #define CHROOT_NSCONNECT (PATH_CHROOT_REL | PATH_CHROOT_NSCONNECT) /** * 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) * @buflen: length of @buf * @name: Returns - pointer for start of path name with in @buf (NOT NULL) * @flags: flags controlling path lookup * * 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 *          to a position in @buf */static int d_namespace_path(struct path *path, char *buf, int buflen,			    char **name, int flags){	char *res;	int error = 0;	int connected = 1; 	if (path->mnt->mnt_flags & MNT_INTERNAL) {		/* it's not mounted anywhere */		res = dentry_path(path->dentry, buf, buflen);		*name = res;		if (IS_ERR(res)) {			*name = buf;			return PTR_ERR(res);		}		if (path->dentry->d_sb->s_magic == PROC_SUPER_MAGIC &&		    strncmp(*name, "/sys/", 5) == 0) {			/* TODO: convert over to using a per namespace			 * control instead of hard coded /proc			 */			return prepend(name, *name - buf, "/proc", 5);		}		return 0;	} 	/* resolve paths relative to chroot?*/	if (flags & PATH_CHROOT_REL) {		struct path root;		get_fs_root(current->fs, &root);		res = __d_path(path, &root, buf, buflen);		if (res && !IS_ERR(res)) {			/* everything's fine */			*name = res;			path_put(&root);			goto ok;		}		path_put(&root);		connected = 0;	} 	res = d_absolute_path(path, buf, buflen); 	*name = res;	/* handle error conditions - and still allow a partial path to	 * be returned.	 */	if (IS_ERR(res)) {		error = PTR_ERR(res);		*name = buf;		goto out;	}	if (!our_mnt(path->mnt))		connected = 0; ok:	/* Handle two cases:	 * 1. A deleted dentry && profile is not allowing mediation of deleted	 * 2. On some filesystems, newly allocated dentries appear to the	 *    security_path hooks as a deleted dentry except without an inode	 *    allocated.	 */	if (d_unlinked(path->dentry) && path->dentry->d_inode &&	    !(flags & PATH_MEDIATE_DELETED)) {			error = -ENOENT;			goto out;	} 	/* 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.	 */	if (!connected) {		if (!(flags & PATH_CONNECT_PATH) &&			   !(((flags & CHROOT_NSCONNECT) == CHROOT_NSCONNECT) &&			     our_mnt(path->mnt))) {			/* disconnected path, don't return pathname starting			 * with '/'			 */			error = -ESTALE;			if (*res == '/')				*name = res + 1;		}	} out:	return error;} /** * get_name_to_buffer - get the pathname to a buffer ensure dir / is appended * @path: path to get name for  (NOT NULL) * @flags: flags controlling path lookup * @buffer: buffer to put name in  (NOT NULL) * @size: size of buffer * @name: Returns - contains position of path name in @buffer (NOT NULL) * * Returns: %0 else error on failure */static int get_name_to_buffer(struct path *path, int flags, char *buffer,			      int size, char **name){	int adjust = (flags & PATH_IS_DIR) ? 1 : 0;	int error = d_namespace_path(path, buffer, size - adjust, name, flags); 	if (!error && (flags & PATH_IS_DIR) && (*name)[1] != '\0')		/*		 * Append "/" to the pathname.  The root directory is a special		 * case; it already ends in slash.		 */		strcpy(&buffer[size - 2], "/"); 	return error;} /** * aa_get_name - compute the pathname of a file * @path: path the file  (NOT NULL) * @flags: flags controlling path name generation * @buffer: buffer that aa_get_name() allocated  (NOT NULL) * @name: Returns - the generated path name if !error (NOT NULL) * * @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_get_name(struct path *path, int flags, char **buffer, const char **name){	char *buf, *str = NULL;	int size = 256;	int error; 	*name = NULL;	*buffer = NULL;	for (;;) {		/* freed by caller */		buf = kmalloc(size, GFP_KERNEL);		if (!buf)			return -ENOMEM; 		error = get_name_to_buffer(path, flags, buf, size, &str);		if (error != -ENAMETOOLONG)			break; 		kfree(buf);		size <<= 1;		if (size > aa_g_path_max)			return -ENAMETOOLONG;	}	*buffer = buf;	*name = str; 	return error;}