1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
|
/*
* 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);
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)
return -ENAMETOOLONG;
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;
/* 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 = -EACCES;
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, const char **info)
{
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], "/");
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";
}
return error;
}
/**
* aa_path_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)
* @info: Returns - information on why the path lookup failed (MAYBE 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_path_name(struct path *path, int flags, char **buffer, const char **name,
const char **info)
{
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, info);
if (error != -ENAMETOOLONG)
break;
kfree(buf);
size <<= 1;
if (size > aa_g_path_max)
return -ENAMETOOLONG;
*info = NULL;
}
*buffer = buf;
*name = str;
return error;
}
|
