1 // SPDX-License-Identifier: GPL-2.0
3 * security/tomoyo/realpath.c
5 * Copyright (C) 2005-2011 NTT DATA CORPORATION
9 #include <linux/magic.h>
12 * tomoyo_encode2 - Encode binary string to ascii string.
14 * @str: String in binary format.
15 * @str_len: Size of @str in byte.
17 * Returns pointer to @str in ascii format on success, NULL otherwise.
19 * This function uses kzalloc(), so caller must kfree() if this function
22 char *tomoyo_encode2(const char *str, int str_len)
32 for (i = 0; i < str_len; i++) {
33 const unsigned char c = p[i];
37 else if (c > ' ' && c < 127)
43 /* Reserve space for appending "/". */
44 cp = kzalloc(len + 10, GFP_NOFS);
49 for (i = 0; i < str_len; i++) {
50 const unsigned char c = p[i];
55 } else if (c > ' ' && c < 127) {
59 *cp++ = (c >> 6) + '0';
60 *cp++ = ((c >> 3) & 7) + '0';
61 *cp++ = (c & 7) + '0';
68 * tomoyo_encode - Encode binary string to ascii string.
70 * @str: String in binary format.
72 * Returns pointer to @str in ascii format on success, NULL otherwise.
74 * This function uses kzalloc(), so caller must kfree() if this function
77 char *tomoyo_encode(const char *str)
79 return str ? tomoyo_encode2(str, strlen(str)) : NULL;
83 * tomoyo_get_absolute_path - Get the path of a dentry but ignores chroot'ed root.
85 * @path: Pointer to "struct path".
86 * @buffer: Pointer to buffer to return value in.
87 * @buflen: Sizeof @buffer.
89 * Returns the buffer on success, an error code otherwise.
91 * If dentry is a directory, trailing '/' is appended.
93 static char *tomoyo_get_absolute_path(const struct path *path, char * const buffer,
96 char *pos = ERR_PTR(-ENOMEM);
98 /* go to whatever namespace root we are under */
99 pos = d_absolute_path(path, buffer, buflen - 1);
100 if (!IS_ERR(pos) && *pos == '/' && pos[1]) {
101 struct inode *inode = d_backing_inode(path->dentry);
102 if (inode && S_ISDIR(inode->i_mode)) {
103 buffer[buflen - 2] = '/';
104 buffer[buflen - 1] = '\0';
112 * tomoyo_get_dentry_path - Get the path of a dentry.
114 * @dentry: Pointer to "struct dentry".
115 * @buffer: Pointer to buffer to return value in.
116 * @buflen: Sizeof @buffer.
118 * Returns the buffer on success, an error code otherwise.
120 * If dentry is a directory, trailing '/' is appended.
122 static char *tomoyo_get_dentry_path(struct dentry *dentry, char * const buffer,
125 char *pos = ERR_PTR(-ENOMEM);
127 pos = dentry_path_raw(dentry, buffer, buflen - 1);
128 if (!IS_ERR(pos) && *pos == '/' && pos[1]) {
129 struct inode *inode = d_backing_inode(dentry);
130 if (inode && S_ISDIR(inode->i_mode)) {
131 buffer[buflen - 2] = '/';
132 buffer[buflen - 1] = '\0';
140 * tomoyo_get_local_path - Get the path of a dentry.
142 * @dentry: Pointer to "struct dentry".
143 * @buffer: Pointer to buffer to return value in.
144 * @buflen: Sizeof @buffer.
146 * Returns the buffer on success, an error code otherwise.
148 static char *tomoyo_get_local_path(struct dentry *dentry, char * const buffer,
151 struct super_block *sb = dentry->d_sb;
152 char *pos = tomoyo_get_dentry_path(dentry, buffer, buflen);
155 /* Convert from $PID to self if $PID is current thread. */
156 if (sb->s_magic == PROC_SUPER_MAGIC && *pos == '/') {
158 const pid_t pid = (pid_t) simple_strtoul(pos + 1, &ep, 10);
159 if (*ep == '/' && pid && pid ==
160 task_tgid_nr_ns(current, sb->s_fs_info)) {
164 memmove(pos, "/self", 5);
166 goto prepend_filesystem_name;
168 /* Use filesystem name for unnamed devices. */
169 if (!MAJOR(sb->s_dev))
170 goto prepend_filesystem_name;
172 struct inode *inode = d_backing_inode(sb->s_root);
174 * Use filesystem name if filesystem does not support rename()
177 if (!inode->i_op->rename)
178 goto prepend_filesystem_name;
180 /* Prepend device name. */
184 const dev_t dev = sb->s_dev;
185 name[sizeof(name) - 1] = '\0';
186 snprintf(name, sizeof(name) - 1, "dev(%u,%u):", MAJOR(dev),
188 name_len = strlen(name);
192 memmove(pos, name, name_len);
195 /* Prepend filesystem name. */
196 prepend_filesystem_name:
198 const char *name = sb->s_type->name;
199 const int name_len = strlen(name);
203 memmove(pos, name, name_len);
208 return ERR_PTR(-ENOMEM);
212 * tomoyo_get_socket_name - Get the name of a socket.
214 * @path: Pointer to "struct path".
215 * @buffer: Pointer to buffer to return value in.
216 * @buflen: Sizeof @buffer.
218 * Returns the buffer.
220 static char *tomoyo_get_socket_name(const struct path *path, char * const buffer,
223 struct inode *inode = d_backing_inode(path->dentry);
224 struct socket *sock = inode ? SOCKET_I(inode) : NULL;
225 struct sock *sk = sock ? sock->sk : NULL;
227 snprintf(buffer, buflen, "socket:[family=%u:type=%u:"
228 "protocol=%u]", sk->sk_family, sk->sk_type,
231 snprintf(buffer, buflen, "socket:[unknown]");
237 * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root.
239 * @path: Pointer to "struct path".
241 * Returns the realpath of the given @path on success, NULL otherwise.
243 * If dentry is a directory, trailing '/' is appended.
244 * Characters out of 0x20 < c < 0x7F range are converted to
245 * \ooo style octal string.
246 * Character \ is converted to \\ string.
248 * These functions use kzalloc(), so the caller must call kfree()
249 * if these functions didn't return NULL.
251 char *tomoyo_realpath_from_path(const struct path *path)
255 unsigned int buf_len = PAGE_SIZE / 2;
256 struct dentry *dentry = path->dentry;
257 struct super_block *sb;
266 buf = kmalloc(buf_len, GFP_NOFS);
269 /* To make sure that pos is '\0' terminated. */
270 buf[buf_len - 1] = '\0';
271 /* Get better name for socket. */
272 if (sb->s_magic == SOCKFS_MAGIC) {
273 pos = tomoyo_get_socket_name(path, buf, buf_len - 1);
276 /* For "pipe:[\$]". */
277 if (dentry->d_op && dentry->d_op->d_dname) {
278 pos = dentry->d_op->d_dname(dentry, buf, buf_len - 1);
281 inode = d_backing_inode(sb->s_root);
283 * Get local name for filesystems without rename() operation
284 * or dentry without vfsmount.
287 (!inode->i_op->rename))
288 pos = tomoyo_get_local_path(path->dentry, buf,
290 /* Get absolute name for the rest. */
292 pos = tomoyo_get_absolute_path(path, buf, buf_len - 1);
294 * Fall back to local name if absolute name is not
297 if (pos == ERR_PTR(-EINVAL))
298 pos = tomoyo_get_local_path(path->dentry, buf,
304 name = tomoyo_encode(pos);
309 tomoyo_warn_oom(__func__);
314 * tomoyo_realpath_nofollow - Get realpath of a pathname.
316 * @pathname: The pathname to solve.
318 * Returns the realpath of @pathname on success, NULL otherwise.
320 char *tomoyo_realpath_nofollow(const char *pathname)
324 if (pathname && kern_path(pathname, 0, &path) == 0) {
325 char *buf = tomoyo_realpath_from_path(&path);