2 * AppArmor security module
4 * This file contains AppArmor function for pathnames
6 * Copyright (C) 1998-2008 Novell/SUSE
7 * Copyright 2009-2010 Canonical Ltd.
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
15 #include <linux/magic.h>
16 #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>
24 #include "include/apparmor.h"
25 #include "include/path.h"
26 #include "include/policy.h"
29 /* modified from dcache.c */
30 static int prepend(char **buffer
, int buflen
, const char *str
, int namelen
)
36 memcpy(*buffer
, str
, namelen
);
40 #define CHROOT_NSCONNECT (PATH_CHROOT_REL | PATH_CHROOT_NSCONNECT)
43 * d_namespace_path - lookup a name associated with a given path
44 * @path: path to lookup (NOT NULL)
45 * @buf: buffer to store path to (NOT NULL)
46 * @buflen: length of @buf
47 * @name: Returns - pointer for start of path name with in @buf (NOT NULL)
48 * @flags: flags controlling path lookup
50 * Handle path name lookup.
52 * Returns: %0 else error code if path lookup fails
53 * When no error the path name is returned in @name which points to
54 * to a position in @buf
56 static int d_namespace_path(struct path
*path
, char *buf
, int buflen
,
57 char **name
, int flags
)
63 if (path
->mnt
->mnt_flags
& MNT_INTERNAL
) {
64 /* it's not mounted anywhere */
65 res
= dentry_path(path
->dentry
, buf
, buflen
);
71 if (path
->dentry
->d_sb
->s_magic
== PROC_SUPER_MAGIC
&&
72 strncmp(*name
, "/sys/", 5) == 0) {
73 /* TODO: convert over to using a per namespace
74 * control instead of hard coded /proc
76 return prepend(name
, *name
- buf
, "/proc", 5);
81 /* resolve paths relative to chroot?*/
82 if (flags
& PATH_CHROOT_REL
) {
84 get_fs_root(current
->fs
, &root
);
85 res
= __d_path(path
, &root
, buf
, buflen
);
88 res
= d_absolute_path(path
, buf
, buflen
);
89 if (!our_mnt(path
->mnt
))
93 /* handle error conditions - and still allow a partial path to
96 if (!res
|| IS_ERR(res
)) {
98 res
= dentry_path_raw(path
->dentry
, buf
, buflen
);
100 error
= PTR_ERR(res
);
104 } else if (!our_mnt(path
->mnt
))
110 * 1. A deleted dentry && profile is not allowing mediation of deleted
111 * 2. On some filesystems, newly allocated dentries appear to the
112 * security_path hooks as a deleted dentry except without an inode
115 if (d_unlinked(path
->dentry
) && path
->dentry
->d_inode
&&
116 !(flags
& PATH_MEDIATE_DELETED
)) {
121 /* If the path is not connected to the expected root,
122 * check if it is a sysctl and handle specially else remove any
123 * leading / that __d_path may have returned.
125 * specifically directed to connect the path,
127 * if in a chroot and doing chroot relative paths and the path
128 * resolves to the namespace root (would be connected outside
129 * of chroot) and specifically directed to connect paths to
133 if (!(flags
& PATH_CONNECT_PATH
) &&
134 !(((flags
& CHROOT_NSCONNECT
) == CHROOT_NSCONNECT
) &&
135 our_mnt(path
->mnt
))) {
136 /* disconnected path, don't return pathname starting
150 * get_name_to_buffer - get the pathname to a buffer ensure dir / is appended
151 * @path: path to get name for (NOT NULL)
152 * @flags: flags controlling path lookup
153 * @buffer: buffer to put name in (NOT NULL)
154 * @size: size of buffer
155 * @name: Returns - contains position of path name in @buffer (NOT NULL)
157 * Returns: %0 else error on failure
159 static int get_name_to_buffer(struct path
*path
, int flags
, char *buffer
,
160 int size
, char **name
, const char **info
)
162 int adjust
= (flags
& PATH_IS_DIR
) ? 1 : 0;
163 int error
= d_namespace_path(path
, buffer
, size
- adjust
, name
, flags
);
165 if (!error
&& (flags
& PATH_IS_DIR
) && (*name
)[1] != '\0')
167 * Append "/" to the pathname. The root directory is a special
168 * case; it already ends in slash.
170 strcpy(&buffer
[size
- 2], "/");
173 if (error
== -ENOENT
)
174 *info
= "Failed name lookup - deleted entry";
175 else if (error
== -ESTALE
)
176 *info
= "Failed name lookup - disconnected path";
177 else if (error
== -ENAMETOOLONG
)
178 *info
= "Failed name lookup - name too long";
180 *info
= "Failed name lookup";
187 * aa_path_name - compute the pathname of a file
188 * @path: path the file (NOT NULL)
189 * @flags: flags controlling path name generation
190 * @buffer: buffer that aa_get_name() allocated (NOT NULL)
191 * @name: Returns - the generated path name if !error (NOT NULL)
192 * @info: Returns - information on why the path lookup failed (MAYBE NULL)
194 * @name is a pointer to the beginning of the pathname (which usually differs
195 * from the beginning of the buffer), or NULL. If there is an error @name
196 * may contain a partial or invalid name that can be used for audit purposes,
197 * but it can not be used for mediation.
199 * We need PATH_IS_DIR to indicate whether the file is a directory or not
200 * because the file may not yet exist, and so we cannot check the inode's
203 * Returns: %0 else error code if could retrieve name
205 int aa_path_name(struct path
*path
, int flags
, char **buffer
, const char **name
,
208 char *buf
, *str
= NULL
;
215 /* freed by caller */
216 buf
= kmalloc(size
, GFP_KERNEL
);
220 error
= get_name_to_buffer(path
, flags
, buf
, size
, &str
, info
);
221 if (error
!= -ENAMETOOLONG
)
226 if (size
> aa_g_path_max
)
227 return -ENAMETOOLONG
;