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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * AppArmor security module
4 *
5 * This file contains AppArmor function for pathnames
6 *
7 * Copyright (C) 1998-2008 Novell/SUSE
8 * Copyright 2009-2010 Canonical Ltd.
9 */
10
11#include <linux/magic.h>
12#include <linux/mount.h>
13#include <linux/namei.h>
14#include <linux/nsproxy.h>
15#include <linux/path.h>
16#include <linux/sched.h>
17#include <linux/slab.h>
18#include <linux/fs_struct.h>
19
20#include "include/apparmor.h"
21#include "include/path.h"
22#include "include/policy.h"
23
24/* modified from dcache.c */
25static int prepend(char **buffer, int buflen, const char *str, int namelen)
26{
27 buflen -= namelen;
28 if (buflen < 0)
29 return -ENAMETOOLONG;
30 *buffer -= namelen;
31 memcpy(*buffer, str, namelen);
32 return 0;
33}
34
35#define CHROOT_NSCONNECT (PATH_CHROOT_REL | PATH_CHROOT_NSCONNECT)
36
37/* If the path is not connected to the expected root,
38 * check if it is a sysctl and handle specially else remove any
39 * leading / that __d_path may have returned.
40 * Unless
41 * specifically directed to connect the path,
42 * OR
43 * if in a chroot and doing chroot relative paths and the path
44 * resolves to the namespace root (would be connected outside
45 * of chroot) and specifically directed to connect paths to
46 * namespace root.
47 */
48static int disconnect(const struct path *path, char *buf, char **name,
49 int flags, const char *disconnected)
50{
51 int error = 0;
52
53 if (!(flags & PATH_CONNECT_PATH) &&
54 !(((flags & CHROOT_NSCONNECT) == CHROOT_NSCONNECT) &&
55 our_mnt(path->mnt))) {
56 /* disconnected path, don't return pathname starting
57 * with '/'
58 */
59 error = -EACCES;
60 if (**name == '/')
61 *name = *name + 1;
62 } else {
63 if (**name != '/')
64 /* CONNECT_PATH with missing root */
65 error = prepend(name, *name - buf, "/", 1);
66 if (!error && disconnected)
67 error = prepend(name, *name - buf, disconnected,
68 strlen(disconnected));
69 }
70
71 return error;
72}
73
74/**
75 * d_namespace_path - lookup a name associated with a given path
76 * @path: path to lookup (NOT NULL)
77 * @buf: buffer to store path to (NOT NULL)
78 * @name: Returns - pointer for start of path name with in @buf (NOT NULL)
79 * @flags: flags controlling path lookup
80 * @disconnected: string to prefix to disconnected paths
81 *
82 * Handle path name lookup.
83 *
84 * Returns: %0 else error code if path lookup fails
85 * When no error the path name is returned in @name which points to
86 * a position in @buf
87 */
88static int d_namespace_path(const struct path *path, char *buf, char **name,
89 int flags, const char *disconnected)
90{
91 char *res;
92 int error = 0;
93 int connected = 1;
94 int isdir = (flags & PATH_IS_DIR) ? 1 : 0;
95 int buflen = aa_g_path_max - isdir;
96
97 if (path->mnt->mnt_flags & MNT_INTERNAL) {
98 /* it's not mounted anywhere */
99 res = dentry_path(path->dentry, buf, buflen);
100 *name = res;
101 if (IS_ERR(res)) {
102 *name = buf;
103 return PTR_ERR(res);
104 }
105 if (path->dentry->d_sb->s_magic == PROC_SUPER_MAGIC &&
106 strncmp(*name, "/sys/", 5) == 0) {
107 /* TODO: convert over to using a per namespace
108 * control instead of hard coded /proc
109 */
110 error = prepend(name, *name - buf, "/proc", 5);
111 goto out;
112 } else
113 error = disconnect(path, buf, name, flags,
114 disconnected);
115 goto out;
116 }
117
118 /* resolve paths relative to chroot?*/
119 if (flags & PATH_CHROOT_REL) {
120 struct path root;
121 get_fs_root(current->fs, &root);
122 res = __d_path(path, &root, buf, buflen);
123 path_put(&root);
124 } else {
125 res = d_absolute_path(path, buf, buflen);
126 if (!our_mnt(path->mnt))
127 connected = 0;
128 }
129
130 /* handle error conditions - and still allow a partial path to
131 * be returned.
132 */
133 if (!res || IS_ERR(res)) {
134 if (PTR_ERR(res) == -ENAMETOOLONG) {
135 error = -ENAMETOOLONG;
136 *name = buf;
137 goto out;
138 }
139 connected = 0;
140 res = dentry_path_raw(path->dentry, buf, buflen);
141 if (IS_ERR(res)) {
142 error = PTR_ERR(res);
143 *name = buf;
144 goto out;
145 }
146 } else if (!our_mnt(path->mnt))
147 connected = 0;
148
149 *name = res;
150
151 if (!connected)
152 error = disconnect(path, buf, name, flags, disconnected);
153
154 /* Handle two cases:
155 * 1. A deleted dentry && profile is not allowing mediation of deleted
156 * 2. On some filesystems, newly allocated dentries appear to the
157 * security_path hooks as a deleted dentry except without an inode
158 * allocated.
159 */
160 if (d_unlinked(path->dentry) && d_is_positive(path->dentry) &&
161 !(flags & (PATH_MEDIATE_DELETED | PATH_DELEGATE_DELETED))) {
162 error = -ENOENT;
163 goto out;
164 }
165
166out:
167 /*
168 * Append "/" to the pathname. The root directory is a special
169 * case; it already ends in slash.
170 */
171 if (!error && isdir && ((*name)[1] != '\0' || (*name)[0] != '/'))
172 strcpy(&buf[aa_g_path_max - 2], "/");
173
174 return error;
175}
176
177/**
178 * aa_path_name - get the pathname to a buffer ensure dir / is appended
179 * @path: path the file (NOT NULL)
180 * @flags: flags controlling path name generation
181 * @buffer: buffer to put name in (NOT NULL)
182 * @name: Returns - the generated path name if !error (NOT NULL)
183 * @info: Returns - information on why the path lookup failed (MAYBE NULL)
184 * @disconnected: string to prepend to disconnected paths
185 *
186 * @name is a pointer to the beginning of the pathname (which usually differs
187 * from the beginning of the buffer), or NULL. If there is an error @name
188 * may contain a partial or invalid name that can be used for audit purposes,
189 * but it can not be used for mediation.
190 *
191 * We need PATH_IS_DIR to indicate whether the file is a directory or not
192 * because the file may not yet exist, and so we cannot check the inode's
193 * file type.
194 *
195 * Returns: %0 else error code if could retrieve name
196 */
197int aa_path_name(const struct path *path, int flags, char *buffer,
198 const char **name, const char **info, const char *disconnected)
199{
200 char *str = NULL;
201 int error = d_namespace_path(path, buffer, &str, flags, disconnected);
202
203 if (info && error) {
204 if (error == -ENOENT)
205 *info = "Failed name lookup - deleted entry";
206 else if (error == -EACCES)
207 *info = "Failed name lookup - disconnected path";
208 else if (error == -ENAMETOOLONG)
209 *info = "Failed name lookup - name too long";
210 else
211 *info = "Failed name lookup";
212 }
213
214 *name = str;
215
216 return error;
217}
1/*
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>
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>
23
24#include "include/apparmor.h"
25#include "include/path.h"
26#include "include/policy.h"
27
28/* 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
41/* 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,
53 int flags, const char *disconnected)
54{
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;
66 } 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 }
74
75 return error;
76}
77
78/**
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)
82 * @name: Returns - pointer for start of path name with in @buf (NOT NULL)
83 * @flags: flags controlling path lookup
84 * @disconnected: string to prefix to disconnected paths
85 *
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 */
92static int d_namespace_path(const struct path *path, char *buf, char **name,
93 int flags, const char *disconnected)
94{
95 char *res;
96 int error = 0;
97 int connected = 1;
98 int isdir = (flags & PATH_IS_DIR) ? 1 : 0;
99 int buflen = aa_g_path_max - isdir;
100
101 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 */
114 error = prepend(name, *name - buf, "/proc", 5);
115 goto out;
116 } else
117 error = disconnect(path, buf, name, flags,
118 disconnected);
119 goto out;
120 }
121
122 /* 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);
127 path_put(&root);
128 } else {
129 res = d_absolute_path(path, buf, buflen);
130 if (!our_mnt(path->mnt))
131 connected = 0;
132 }
133
134 /* handle error conditions - and still allow a partial path to
135 * be returned.
136 */
137 if (!res || IS_ERR(res)) {
138 if (PTR_ERR(res) == -ENAMETOOLONG) {
139 error = -ENAMETOOLONG;
140 *name = buf;
141 goto out;
142 }
143 connected = 0;
144 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))
151 connected = 0;
152
153 *name = res;
154
155 if (!connected)
156 error = disconnect(path, buf, name, flags, disconnected);
157
158 /* 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 */
164 if (d_unlinked(path->dentry) && d_is_positive(path->dentry) &&
165 !(flags & (PATH_MEDIATE_DELETED | PATH_DELEGATE_DELETED))) {
166 error = -ENOENT;
167 goto out;
168 }
169
170out:
171 /*
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], "/");
177
178 return error;
179}
180
181/**
182 * aa_path_name - get the pathname to a buffer ensure dir / is appended
183 * @path: path the file (NOT NULL)
184 * @flags: flags controlling path name generation
185 * @buffer: buffer to put name in (NOT NULL)
186 * @name: Returns - the generated path name if !error (NOT NULL)
187 * @info: Returns - information on why the path lookup failed (MAYBE NULL)
188 * @disconnected: string to prepend to disconnected paths
189 *
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 */
201int aa_path_name(const struct path *path, int flags, char *buffer,
202 const char **name, const char **info, const char *disconnected)
203{
204 char *str = NULL;
205 int error = d_namespace_path(path, buffer, &str, flags, disconnected);
206
207 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";
216 }
217
218 *name = str;
219
220 return error;
221}