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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * security/tomoyo/realpath.c
4 *
5 * Copyright (C) 2005-2011 NTT DATA CORPORATION
6 */
7
8#include "common.h"
9#include <linux/magic.h>
10#include <linux/proc_fs.h>
11
12/**
13 * tomoyo_encode2 - Encode binary string to ascii string.
14 *
15 * @str: String in binary format.
16 * @str_len: Size of @str in byte.
17 *
18 * Returns pointer to @str in ascii format on success, NULL otherwise.
19 *
20 * This function uses kzalloc(), so caller must kfree() if this function
21 * didn't return NULL.
22 */
23char *tomoyo_encode2(const char *str, int str_len)
24{
25 int i;
26 int len = 0;
27 const char *p = str;
28 char *cp;
29 char *cp0;
30
31 if (!p)
32 return NULL;
33 for (i = 0; i < str_len; i++) {
34 const unsigned char c = p[i];
35
36 if (c == '\\')
37 len += 2;
38 else if (c > ' ' && c < 127)
39 len++;
40 else
41 len += 4;
42 }
43 len++;
44 /* Reserve space for appending "/". */
45 cp = kzalloc(len + 10, GFP_NOFS);
46 if (!cp)
47 return NULL;
48 cp0 = cp;
49 p = str;
50 for (i = 0; i < str_len; i++) {
51 const unsigned char c = p[i];
52
53 if (c == '\\') {
54 *cp++ = '\\';
55 *cp++ = '\\';
56 } else if (c > ' ' && c < 127) {
57 *cp++ = c;
58 } else {
59 *cp++ = '\\';
60 *cp++ = (c >> 6) + '0';
61 *cp++ = ((c >> 3) & 7) + '0';
62 *cp++ = (c & 7) + '0';
63 }
64 }
65 return cp0;
66}
67
68/**
69 * tomoyo_encode - Encode binary string to ascii string.
70 *
71 * @str: String in binary format.
72 *
73 * Returns pointer to @str in ascii format on success, NULL otherwise.
74 *
75 * This function uses kzalloc(), so caller must kfree() if this function
76 * didn't return NULL.
77 */
78char *tomoyo_encode(const char *str)
79{
80 return str ? tomoyo_encode2(str, strlen(str)) : NULL;
81}
82
83/**
84 * tomoyo_get_absolute_path - Get the path of a dentry but ignores chroot'ed root.
85 *
86 * @path: Pointer to "struct path".
87 * @buffer: Pointer to buffer to return value in.
88 * @buflen: Sizeof @buffer.
89 *
90 * Returns the buffer on success, an error code otherwise.
91 *
92 * If dentry is a directory, trailing '/' is appended.
93 */
94static char *tomoyo_get_absolute_path(const struct path *path, char * const buffer,
95 const int buflen)
96{
97 char *pos = ERR_PTR(-ENOMEM);
98
99 if (buflen >= 256) {
100 /* go to whatever namespace root we are under */
101 pos = d_absolute_path(path, buffer, buflen - 1);
102 if (!IS_ERR(pos) && *pos == '/' && pos[1]) {
103 struct inode *inode = d_backing_inode(path->dentry);
104
105 if (inode && S_ISDIR(inode->i_mode)) {
106 buffer[buflen - 2] = '/';
107 buffer[buflen - 1] = '\0';
108 }
109 }
110 }
111 return pos;
112}
113
114/**
115 * tomoyo_get_dentry_path - Get the path of a dentry.
116 *
117 * @dentry: Pointer to "struct dentry".
118 * @buffer: Pointer to buffer to return value in.
119 * @buflen: Sizeof @buffer.
120 *
121 * Returns the buffer on success, an error code otherwise.
122 *
123 * If dentry is a directory, trailing '/' is appended.
124 */
125static char *tomoyo_get_dentry_path(struct dentry *dentry, char * const buffer,
126 const int buflen)
127{
128 char *pos = ERR_PTR(-ENOMEM);
129
130 if (buflen >= 256) {
131 pos = dentry_path_raw(dentry, buffer, buflen - 1);
132 if (!IS_ERR(pos) && *pos == '/' && pos[1]) {
133 struct inode *inode = d_backing_inode(dentry);
134
135 if (inode && S_ISDIR(inode->i_mode)) {
136 buffer[buflen - 2] = '/';
137 buffer[buflen - 1] = '\0';
138 }
139 }
140 }
141 return pos;
142}
143
144/**
145 * tomoyo_get_local_path - Get the path of a dentry.
146 *
147 * @dentry: Pointer to "struct dentry".
148 * @buffer: Pointer to buffer to return value in.
149 * @buflen: Sizeof @buffer.
150 *
151 * Returns the buffer on success, an error code otherwise.
152 */
153static char *tomoyo_get_local_path(struct dentry *dentry, char * const buffer,
154 const int buflen)
155{
156 struct super_block *sb = dentry->d_sb;
157 char *pos = tomoyo_get_dentry_path(dentry, buffer, buflen);
158
159 if (IS_ERR(pos))
160 return pos;
161 /* Convert from $PID to self if $PID is current thread. */
162 if (sb->s_magic == PROC_SUPER_MAGIC && *pos == '/') {
163 char *ep;
164 const pid_t pid = (pid_t) simple_strtoul(pos + 1, &ep, 10);
165 struct pid_namespace *proc_pidns = proc_pid_ns(sb);
166
167 if (*ep == '/' && pid && pid ==
168 task_tgid_nr_ns(current, proc_pidns)) {
169 pos = ep - 5;
170 if (pos < buffer)
171 goto out;
172 memmove(pos, "/self", 5);
173 }
174 goto prepend_filesystem_name;
175 }
176 /* Use filesystem name for unnamed devices. */
177 if (!MAJOR(sb->s_dev))
178 goto prepend_filesystem_name;
179 {
180 struct inode *inode = d_backing_inode(sb->s_root);
181
182 /*
183 * Use filesystem name if filesystem does not support rename()
184 * operation.
185 */
186 if (!inode->i_op->rename)
187 goto prepend_filesystem_name;
188 }
189 /* Prepend device name. */
190 {
191 char name[64];
192 int name_len;
193 const dev_t dev = sb->s_dev;
194
195 name[sizeof(name) - 1] = '\0';
196 snprintf(name, sizeof(name) - 1, "dev(%u,%u):", MAJOR(dev),
197 MINOR(dev));
198 name_len = strlen(name);
199 pos -= name_len;
200 if (pos < buffer)
201 goto out;
202 memmove(pos, name, name_len);
203 return pos;
204 }
205 /* Prepend filesystem name. */
206prepend_filesystem_name:
207 {
208 const char *name = sb->s_type->name;
209 const int name_len = strlen(name);
210
211 pos -= name_len + 1;
212 if (pos < buffer)
213 goto out;
214 memmove(pos, name, name_len);
215 pos[name_len] = ':';
216 }
217 return pos;
218out:
219 return ERR_PTR(-ENOMEM);
220}
221
222/**
223 * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root.
224 *
225 * @path: Pointer to "struct path".
226 *
227 * Returns the realpath of the given @path on success, NULL otherwise.
228 *
229 * If dentry is a directory, trailing '/' is appended.
230 * Characters out of 0x20 < c < 0x7F range are converted to
231 * \ooo style octal string.
232 * Character \ is converted to \\ string.
233 *
234 * These functions use kzalloc(), so the caller must call kfree()
235 * if these functions didn't return NULL.
236 */
237char *tomoyo_realpath_from_path(const struct path *path)
238{
239 char *buf = NULL;
240 char *name = NULL;
241 unsigned int buf_len = PAGE_SIZE / 2;
242 struct dentry *dentry = path->dentry;
243 struct super_block *sb = dentry->d_sb;
244
245 while (1) {
246 char *pos;
247 struct inode *inode;
248
249 buf_len <<= 1;
250 kfree(buf);
251 buf = kmalloc(buf_len, GFP_NOFS);
252 if (!buf)
253 break;
254 /* To make sure that pos is '\0' terminated. */
255 buf[buf_len - 1] = '\0';
256 /* For "pipe:[\$]" and "socket:[\$]". */
257 if (dentry->d_op && dentry->d_op->d_dname) {
258 pos = dentry->d_op->d_dname(dentry, buf, buf_len - 1);
259 goto encode;
260 }
261 inode = d_backing_inode(sb->s_root);
262 /*
263 * Get local name for filesystems without rename() operation
264 */
265 if ((!inode->i_op->rename &&
266 !(sb->s_type->fs_flags & FS_REQUIRES_DEV)))
267 pos = tomoyo_get_local_path(path->dentry, buf,
268 buf_len - 1);
269 /* Get absolute name for the rest. */
270 else {
271 pos = tomoyo_get_absolute_path(path, buf, buf_len - 1);
272 /*
273 * Fall back to local name if absolute name is not
274 * available.
275 */
276 if (pos == ERR_PTR(-EINVAL))
277 pos = tomoyo_get_local_path(path->dentry, buf,
278 buf_len - 1);
279 }
280encode:
281 if (IS_ERR(pos))
282 continue;
283 name = tomoyo_encode(pos);
284 break;
285 }
286 kfree(buf);
287 if (!name)
288 tomoyo_warn_oom(__func__);
289 return name;
290}
291
292/**
293 * tomoyo_realpath_nofollow - Get realpath of a pathname.
294 *
295 * @pathname: The pathname to solve.
296 *
297 * Returns the realpath of @pathname on success, NULL otherwise.
298 */
299char *tomoyo_realpath_nofollow(const char *pathname)
300{
301 struct path path;
302
303 if (pathname && kern_path(pathname, 0, &path) == 0) {
304 char *buf = tomoyo_realpath_from_path(&path);
305
306 path_put(&path);
307 return buf;
308 }
309 return NULL;
310}
1/*
2 * security/tomoyo/realpath.c
3 *
4 * Copyright (C) 2005-2011 NTT DATA CORPORATION
5 */
6
7#include <linux/types.h>
8#include <linux/mount.h>
9#include <linux/mnt_namespace.h>
10#include <linux/fs_struct.h>
11#include <linux/magic.h>
12#include <linux/slab.h>
13#include <net/sock.h>
14#include "common.h"
15#include "../../fs/internal.h"
16
17/**
18 * tomoyo_encode: Convert binary string to ascii string.
19 *
20 * @str: String in binary format.
21 *
22 * Returns pointer to @str in ascii format on success, NULL otherwise.
23 *
24 * This function uses kzalloc(), so caller must kfree() if this function
25 * didn't return NULL.
26 */
27char *tomoyo_encode(const char *str)
28{
29 int len = 0;
30 const char *p = str;
31 char *cp;
32 char *cp0;
33
34 if (!p)
35 return NULL;
36 while (*p) {
37 const unsigned char c = *p++;
38 if (c == '\\')
39 len += 2;
40 else if (c > ' ' && c < 127)
41 len++;
42 else
43 len += 4;
44 }
45 len++;
46 /* Reserve space for appending "/". */
47 cp = kzalloc(len + 10, GFP_NOFS);
48 if (!cp)
49 return NULL;
50 cp0 = cp;
51 p = str;
52 while (*p) {
53 const unsigned char c = *p++;
54
55 if (c == '\\') {
56 *cp++ = '\\';
57 *cp++ = '\\';
58 } else if (c > ' ' && c < 127) {
59 *cp++ = c;
60 } else {
61 *cp++ = '\\';
62 *cp++ = (c >> 6) + '0';
63 *cp++ = ((c >> 3) & 7) + '0';
64 *cp++ = (c & 7) + '0';
65 }
66 }
67 return cp0;
68}
69
70/**
71 * tomoyo_get_absolute_path - Get the path of a dentry but ignores chroot'ed root.
72 *
73 * @path: Pointer to "struct path".
74 * @buffer: Pointer to buffer to return value in.
75 * @buflen: Sizeof @buffer.
76 *
77 * Returns the buffer on success, an error code otherwise.
78 *
79 * If dentry is a directory, trailing '/' is appended.
80 */
81static char *tomoyo_get_absolute_path(struct path *path, char * const buffer,
82 const int buflen)
83{
84 char *pos = ERR_PTR(-ENOMEM);
85 if (buflen >= 256) {
86 struct path ns_root = { };
87 /* go to whatever namespace root we are under */
88 pos = __d_path(path, &ns_root, buffer, buflen - 1);
89 if (!IS_ERR(pos) && *pos == '/' && pos[1]) {
90 struct inode *inode = path->dentry->d_inode;
91 if (inode && S_ISDIR(inode->i_mode)) {
92 buffer[buflen - 2] = '/';
93 buffer[buflen - 1] = '\0';
94 }
95 }
96 }
97 return pos;
98}
99
100/**
101 * tomoyo_get_dentry_path - Get the path of a dentry.
102 *
103 * @dentry: Pointer to "struct dentry".
104 * @buffer: Pointer to buffer to return value in.
105 * @buflen: Sizeof @buffer.
106 *
107 * Returns the buffer on success, an error code otherwise.
108 *
109 * If dentry is a directory, trailing '/' is appended.
110 */
111static char *tomoyo_get_dentry_path(struct dentry *dentry, char * const buffer,
112 const int buflen)
113{
114 char *pos = ERR_PTR(-ENOMEM);
115 if (buflen >= 256) {
116 pos = dentry_path_raw(dentry, buffer, buflen - 1);
117 if (!IS_ERR(pos) && *pos == '/' && pos[1]) {
118 struct inode *inode = dentry->d_inode;
119 if (inode && S_ISDIR(inode->i_mode)) {
120 buffer[buflen - 2] = '/';
121 buffer[buflen - 1] = '\0';
122 }
123 }
124 }
125 return pos;
126}
127
128/**
129 * tomoyo_get_local_path - Get the path of a dentry.
130 *
131 * @dentry: Pointer to "struct dentry".
132 * @buffer: Pointer to buffer to return value in.
133 * @buflen: Sizeof @buffer.
134 *
135 * Returns the buffer on success, an error code otherwise.
136 */
137static char *tomoyo_get_local_path(struct dentry *dentry, char * const buffer,
138 const int buflen)
139{
140 struct super_block *sb = dentry->d_sb;
141 char *pos = tomoyo_get_dentry_path(dentry, buffer, buflen);
142 if (IS_ERR(pos))
143 return pos;
144 /* Convert from $PID to self if $PID is current thread. */
145 if (sb->s_magic == PROC_SUPER_MAGIC && *pos == '/') {
146 char *ep;
147 const pid_t pid = (pid_t) simple_strtoul(pos + 1, &ep, 10);
148 if (*ep == '/' && pid && pid ==
149 task_tgid_nr_ns(current, sb->s_fs_info)) {
150 pos = ep - 5;
151 if (pos < buffer)
152 goto out;
153 memmove(pos, "/self", 5);
154 }
155 goto prepend_filesystem_name;
156 }
157 /* Use filesystem name for unnamed devices. */
158 if (!MAJOR(sb->s_dev))
159 goto prepend_filesystem_name;
160 {
161 struct inode *inode = sb->s_root->d_inode;
162 /*
163 * Use filesystem name if filesystem does not support rename()
164 * operation.
165 */
166 if (inode->i_op && !inode->i_op->rename)
167 goto prepend_filesystem_name;
168 }
169 /* Prepend device name. */
170 {
171 char name[64];
172 int name_len;
173 const dev_t dev = sb->s_dev;
174 name[sizeof(name) - 1] = '\0';
175 snprintf(name, sizeof(name) - 1, "dev(%u,%u):", MAJOR(dev),
176 MINOR(dev));
177 name_len = strlen(name);
178 pos -= name_len;
179 if (pos < buffer)
180 goto out;
181 memmove(pos, name, name_len);
182 return pos;
183 }
184 /* Prepend filesystem name. */
185prepend_filesystem_name:
186 {
187 const char *name = sb->s_type->name;
188 const int name_len = strlen(name);
189 pos -= name_len + 1;
190 if (pos < buffer)
191 goto out;
192 memmove(pos, name, name_len);
193 pos[name_len] = ':';
194 }
195 return pos;
196out:
197 return ERR_PTR(-ENOMEM);
198}
199
200/**
201 * tomoyo_get_socket_name - Get the name of a socket.
202 *
203 * @path: Pointer to "struct path".
204 * @buffer: Pointer to buffer to return value in.
205 * @buflen: Sizeof @buffer.
206 *
207 * Returns the buffer.
208 */
209static char *tomoyo_get_socket_name(struct path *path, char * const buffer,
210 const int buflen)
211{
212 struct inode *inode = path->dentry->d_inode;
213 struct socket *sock = inode ? SOCKET_I(inode) : NULL;
214 struct sock *sk = sock ? sock->sk : NULL;
215 if (sk) {
216 snprintf(buffer, buflen, "socket:[family=%u:type=%u:"
217 "protocol=%u]", sk->sk_family, sk->sk_type,
218 sk->sk_protocol);
219 } else {
220 snprintf(buffer, buflen, "socket:[unknown]");
221 }
222 return buffer;
223}
224
225/**
226 * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root.
227 *
228 * @path: Pointer to "struct path".
229 *
230 * Returns the realpath of the given @path on success, NULL otherwise.
231 *
232 * If dentry is a directory, trailing '/' is appended.
233 * Characters out of 0x20 < c < 0x7F range are converted to
234 * \ooo style octal string.
235 * Character \ is converted to \\ string.
236 *
237 * These functions use kzalloc(), so the caller must call kfree()
238 * if these functions didn't return NULL.
239 */
240char *tomoyo_realpath_from_path(struct path *path)
241{
242 char *buf = NULL;
243 char *name = NULL;
244 unsigned int buf_len = PAGE_SIZE / 2;
245 struct dentry *dentry = path->dentry;
246 struct super_block *sb;
247 if (!dentry)
248 return NULL;
249 sb = dentry->d_sb;
250 while (1) {
251 char *pos;
252 struct inode *inode;
253 buf_len <<= 1;
254 kfree(buf);
255 buf = kmalloc(buf_len, GFP_NOFS);
256 if (!buf)
257 break;
258 /* To make sure that pos is '\0' terminated. */
259 buf[buf_len - 1] = '\0';
260 /* Get better name for socket. */
261 if (sb->s_magic == SOCKFS_MAGIC) {
262 pos = tomoyo_get_socket_name(path, buf, buf_len - 1);
263 goto encode;
264 }
265 /* For "pipe:[\$]". */
266 if (dentry->d_op && dentry->d_op->d_dname) {
267 pos = dentry->d_op->d_dname(dentry, buf, buf_len - 1);
268 goto encode;
269 }
270 inode = sb->s_root->d_inode;
271 /*
272 * Get local name for filesystems without rename() operation
273 * or dentry without vfsmount.
274 */
275 if (!path->mnt || (inode->i_op && !inode->i_op->rename))
276 pos = tomoyo_get_local_path(path->dentry, buf,
277 buf_len - 1);
278 /* Get absolute name for the rest. */
279 else
280 pos = tomoyo_get_absolute_path(path, buf, buf_len - 1);
281encode:
282 if (IS_ERR(pos))
283 continue;
284 name = tomoyo_encode(pos);
285 break;
286 }
287 kfree(buf);
288 if (!name)
289 tomoyo_warn_oom(__func__);
290 return name;
291}
292
293/**
294 * tomoyo_realpath_nofollow - Get realpath of a pathname.
295 *
296 * @pathname: The pathname to solve.
297 *
298 * Returns the realpath of @pathname on success, NULL otherwise.
299 */
300char *tomoyo_realpath_nofollow(const char *pathname)
301{
302 struct path path;
303
304 if (pathname && kern_path(pathname, 0, &path) == 0) {
305 char *buf = tomoyo_realpath_from_path(&path);
306 path_put(&path);
307 return buf;
308 }
309 return NULL;
310}