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John Johansencdff2642010-07-29 14:47:57 -07001/*
2 * AppArmor security module
3 *
4 * This file contains AppArmor function for pathnames
5 *
6 * Copyright (C) 1998-2008 Novell/SUSE
7 * Copyright 2009-2010 Canonical Ltd.
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License as
11 * published by the Free Software Foundation, version 2 of the
12 * License.
13 */
14
15#include <linux/magic.h>
John Johansencdff2642010-07-29 14:47:57 -070016#include <linux/mount.h>
17#include <linux/namei.h>
18#include <linux/nsproxy.h>
19#include <linux/path.h>
20#include <linux/sched.h>
21#include <linux/slab.h>
22#include <linux/fs_struct.h>
23
24#include "include/apparmor.h"
25#include "include/path.h"
26#include "include/policy.h"
27
John Johansencdff2642010-07-29 14:47:57 -070028/* modified from dcache.c */
29static int prepend(char **buffer, int buflen, const char *str, int namelen)
30{
31 buflen -= namelen;
32 if (buflen < 0)
33 return -ENAMETOOLONG;
34 *buffer -= namelen;
35 memcpy(*buffer, str, namelen);
36 return 0;
37}
38
39#define CHROOT_NSCONNECT (PATH_CHROOT_REL | PATH_CHROOT_NSCONNECT)
40
John Johansenbd35db82014-07-25 04:02:10 -070041/* If the path is not connected to the expected root,
42 * check if it is a sysctl and handle specially else remove any
43 * leading / that __d_path may have returned.
44 * Unless
45 * specifically directed to connect the path,
46 * OR
47 * if in a chroot and doing chroot relative paths and the path
48 * resolves to the namespace root (would be connected outside
49 * of chroot) and specifically directed to connect paths to
50 * namespace root.
51 */
52static int disconnect(const struct path *path, char *buf, char **name,
John Johansen72c8a762017-05-22 03:06:52 -070053 int flags, const char *disconnected)
John Johansenbd35db82014-07-25 04:02:10 -070054{
55 int error = 0;
56
57 if (!(flags & PATH_CONNECT_PATH) &&
58 !(((flags & CHROOT_NSCONNECT) == CHROOT_NSCONNECT) &&
59 our_mnt(path->mnt))) {
60 /* disconnected path, don't return pathname starting
61 * with '/'
62 */
63 error = -EACCES;
64 if (**name == '/')
65 *name = *name + 1;
John Johansen72c8a762017-05-22 03:06:52 -070066 } else {
67 if (**name != '/')
68 /* CONNECT_PATH with missing root */
69 error = prepend(name, *name - buf, "/", 1);
70 if (!error && disconnected)
71 error = prepend(name, *name - buf, disconnected,
72 strlen(disconnected));
73 }
John Johansenbd35db82014-07-25 04:02:10 -070074
75 return error;
76}
77
John Johansencdff2642010-07-29 14:47:57 -070078/**
79 * d_namespace_path - lookup a name associated with a given path
80 * @path: path to lookup (NOT NULL)
81 * @buf: buffer to store path to (NOT NULL)
John Johansencdff2642010-07-29 14:47:57 -070082 * @name: Returns - pointer for start of path name with in @buf (NOT NULL)
83 * @flags: flags controlling path lookup
John Johansen72c8a762017-05-22 03:06:52 -070084 * @disconnected: string to prefix to disconnected paths
John Johansencdff2642010-07-29 14:47:57 -070085 *
86 * Handle path name lookup.
87 *
88 * Returns: %0 else error code if path lookup fails
89 * When no error the path name is returned in @name which points to
90 * to a position in @buf
91 */
John Johansen4227c332017-05-23 03:25:14 -070092static int d_namespace_path(const struct path *path, char *buf, char **name,
93 int flags, const char *disconnected)
John Johansencdff2642010-07-29 14:47:57 -070094{
John Johansencdff2642010-07-29 14:47:57 -070095 char *res;
Al Viro02125a82011-12-05 08:43:34 -050096 int error = 0;
97 int connected = 1;
John Johansen4227c332017-05-23 03:25:14 -070098 int isdir = (flags & PATH_IS_DIR) ? 1 : 0;
99 int buflen = aa_g_path_max - isdir;
John Johansencdff2642010-07-29 14:47:57 -0700100
Al Viro02125a82011-12-05 08:43:34 -0500101 if (path->mnt->mnt_flags & MNT_INTERNAL) {
102 /* it's not mounted anywhere */
103 res = dentry_path(path->dentry, buf, buflen);
104 *name = res;
105 if (IS_ERR(res)) {
106 *name = buf;
107 return PTR_ERR(res);
108 }
109 if (path->dentry->d_sb->s_magic == PROC_SUPER_MAGIC &&
110 strncmp(*name, "/sys/", 5) == 0) {
111 /* TODO: convert over to using a per namespace
112 * control instead of hard coded /proc
113 */
John Johansen4227c332017-05-23 03:25:14 -0700114 error = prepend(name, *name - buf, "/proc", 5);
115 goto out;
John Johansenbd35db82014-07-25 04:02:10 -0700116 } else
John Johansen4227c332017-05-23 03:25:14 -0700117 error = disconnect(path, buf, name, flags,
118 disconnected);
119 goto out;
John Johansencdff2642010-07-29 14:47:57 -0700120 }
121
Al Viro02125a82011-12-05 08:43:34 -0500122 /* resolve paths relative to chroot?*/
123 if (flags & PATH_CHROOT_REL) {
124 struct path root;
125 get_fs_root(current->fs, &root);
126 res = __d_path(path, &root, buf, buflen);
Al Viro02125a82011-12-05 08:43:34 -0500127 path_put(&root);
John Johansen3372b682012-02-16 06:32:47 -0800128 } else {
John Johansen28042fa2012-02-16 06:21:30 -0800129 res = d_absolute_path(path, buf, buflen);
John Johansen3372b682012-02-16 06:32:47 -0800130 if (!our_mnt(path->mnt))
131 connected = 0;
132 }
John Johansencdff2642010-07-29 14:47:57 -0700133
John Johansencdff2642010-07-29 14:47:57 -0700134 /* handle error conditions - and still allow a partial path to
135 * be returned.
136 */
John Johansen3372b682012-02-16 06:32:47 -0800137 if (!res || IS_ERR(res)) {
John Johansen4227c332017-05-23 03:25:14 -0700138 if (PTR_ERR(res) == -ENAMETOOLONG) {
139 error = -ENAMETOOLONG;
140 *name = buf;
141 goto out;
142 }
John Johansen3372b682012-02-16 06:32:47 -0800143 connected = 0;
John Johansenfbba8d82012-02-16 06:28:50 -0800144 res = dentry_path_raw(path->dentry, buf, buflen);
145 if (IS_ERR(res)) {
146 error = PTR_ERR(res);
147 *name = buf;
148 goto out;
149 };
150 } else if (!our_mnt(path->mnt))
Al Viro02125a82011-12-05 08:43:34 -0500151 connected = 0;
John Johansencdff2642010-07-29 14:47:57 -0700152
John Johansenfbba8d82012-02-16 06:28:50 -0800153 *name = res;
154
John Johansen4227c332017-05-23 03:25:14 -0700155 if (!connected)
156 error = disconnect(path, buf, name, flags, disconnected);
157
John Johansene819ff52010-08-27 18:33:26 -0700158 /* Handle two cases:
159 * 1. A deleted dentry && profile is not allowing mediation of deleted
160 * 2. On some filesystems, newly allocated dentries appear to the
161 * security_path hooks as a deleted dentry except without an inode
162 * allocated.
163 */
David Howells729b8a32015-01-29 12:02:31 +0000164 if (d_unlinked(path->dentry) && d_is_positive(path->dentry) &&
John Johansen4227c332017-05-23 03:25:14 -0700165 !(flags & (PATH_MEDIATE_DELETED | PATH_DELEGATE_DELETED))) {
John Johansencdff2642010-07-29 14:47:57 -0700166 error = -ENOENT;
167 goto out;
John Johansencdff2642010-07-29 14:47:57 -0700168 }
169
John Johansencdff2642010-07-29 14:47:57 -0700170out:
John Johansen4227c332017-05-23 03:25:14 -0700171 /*
172 * Append "/" to the pathname. The root directory is a special
173 * case; it already ends in slash.
174 */
175 if (!error && isdir && ((*name)[1] != '\0' || (*name)[0] != '/'))
176 strcpy(&buf[aa_g_path_max - 2], "/");
John Johansen57fa1e12012-02-16 06:20:33 -0800177
John Johansencdff2642010-07-29 14:47:57 -0700178 return error;
179}
180
181/**
John Johansen4227c332017-05-23 03:25:14 -0700182 * aa_path_name - get the pathname to a buffer ensure dir / is appended
John Johansencdff2642010-07-29 14:47:57 -0700183 * @path: path the file (NOT NULL)
184 * @flags: flags controlling path name generation
John Johansen4227c332017-05-23 03:25:14 -0700185 * @buffer: buffer to put name in (NOT NULL)
John Johansencdff2642010-07-29 14:47:57 -0700186 * @name: Returns - the generated path name if !error (NOT NULL)
John Johansen57fa1e12012-02-16 06:20:33 -0800187 * @info: Returns - information on why the path lookup failed (MAYBE NULL)
John Johansen72c8a762017-05-22 03:06:52 -0700188 * @disconnected: string to prepend to disconnected paths
John Johansencdff2642010-07-29 14:47:57 -0700189 *
190 * @name is a pointer to the beginning of the pathname (which usually differs
191 * from the beginning of the buffer), or NULL. If there is an error @name
192 * may contain a partial or invalid name that can be used for audit purposes,
193 * but it can not be used for mediation.
194 *
195 * We need PATH_IS_DIR to indicate whether the file is a directory or not
196 * because the file may not yet exist, and so we cannot check the inode's
197 * file type.
198 *
199 * Returns: %0 else error code if could retrieve name
200 */
John Johansen4227c332017-05-23 03:25:14 -0700201int aa_path_name(const struct path *path, int flags, char *buffer,
John Johansen72c8a762017-05-22 03:06:52 -0700202 const char **name, const char **info, const char *disconnected)
John Johansencdff2642010-07-29 14:47:57 -0700203{
John Johansen4227c332017-05-23 03:25:14 -0700204 char *str = NULL;
205 int error = d_namespace_path(path, buffer, &str, flags, disconnected);
John Johansencdff2642010-07-29 14:47:57 -0700206
John Johansen4227c332017-05-23 03:25:14 -0700207 if (info && error) {
208 if (error == -ENOENT)
209 *info = "Failed name lookup - deleted entry";
210 else if (error == -EACCES)
211 *info = "Failed name lookup - disconnected path";
212 else if (error == -ENAMETOOLONG)
213 *info = "Failed name lookup - name too long";
214 else
215 *info = "Failed name lookup";
John Johansencdff2642010-07-29 14:47:57 -0700216 }
John Johansen4227c332017-05-23 03:25:14 -0700217
John Johansencdff2642010-07-29 14:47:57 -0700218 *name = str;
219
220 return error;
221}