/* * 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) /* 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){	int error = 0; 	if (!(flags & PATH_CONNECT_PATH) &&	    !(((flags & CHROOT_NSCONNECT) == CHROOT_NSCONNECT) &&	      our_mnt(path->mnt))) {		/* disconnected path, don't return pathname starting		 * with '/'		 */		error = -EACCES;		if (**name == '/')			*name = *name + 1;	} else {		if (**name != '/')			/* CONNECT_PATH with missing root */			error = prepend(name, *name - buf, "/", 1);		if (!error && disconnected)			error = prepend(name, *name - buf, disconnected,					strlen(disconnected));	} 	return error;} /** * 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 *          to a position in @buf */static int d_namespace_path(const struct path *path, char *buf, char **name,			    int flags, const char *disconnected){	char *res;	int error = 0;	int connected = 1;	int isdir = (flags & PATH_IS_DIR) ? 1 : 0;	int buflen = aa_g_path_max - isdir; 	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			 */			error = prepend(name, *name - buf, "/proc", 5);			goto out;		} else			error = disconnect(path, buf, name, flags,					   disconnected);		goto out;	} 	/* 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);		path_put(&root);	} else {		res = d_absolute_path(path, buf, buflen);		if (!our_mnt(path->mnt))			connected = 0;	} 	/* handle error conditions - and still allow a partial path to	 * be returned.	 */	if (!res || IS_ERR(res)) {		if (PTR_ERR(res) == -ENAMETOOLONG) {			error = -ENAMETOOLONG;			*name = buf;			goto out;		}		connected = 0;		res = dentry_path_raw(path->dentry, buf, buflen);		if (IS_ERR(res)) {			error = PTR_ERR(res);			*name = buf;			goto out;		};	} else if (!our_mnt(path->mnt))		connected = 0; 	*name = res; 	if (!connected)		error = disconnect(path, buf, name, flags, disconnected); 	/* 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) && d_is_positive(path->dentry) &&	    !(flags & (PATH_MEDIATE_DELETED | PATH_DELEGATE_DELETED))) {			error = -ENOENT;			goto out;	} out:	/*	 * Append "/" to the pathname.  The root directory is a special	 * case; it already ends in slash.	 */	if (!error && isdir && ((*name)[1] != '\0' || (*name)[0] != '/'))		strcpy(&buf[aa_g_path_max - 2], "/"); 	return error;} /** * 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){	char *str = NULL;	int error = d_namespace_path(path, buffer, &str, flags, disconnected); 	if (info && error) {		if (error == -ENOENT)			*info = "Failed name lookup - deleted entry";		else if (error == -EACCES)			*info = "Failed name lookup - disconnected path";		else if (error == -ENAMETOOLONG)			*info = "Failed name lookup - name too long";		else			*info = "Failed name lookup";	} 	*name = str; 	return error;}