2 * security/tomoyo/realpath.c
4 * Copyright (C) 2005-2011 NTT DATA CORPORATION
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>
15 #include "../../fs/internal.h"
18 * tomoyo_encode2 - Encode binary string to ascii string.
20 * @str: String in binary format.
21 * @str_len: Size of @str in byte.
23 * Returns pointer to @str in ascii format on success, NULL otherwise.
25 * This function uses kzalloc(), so caller must kfree() if this function
28 char *tomoyo_encode2(const char *str, int str_len)
38 for (i = 0; i < str_len; i++) {
39 const unsigned char c = p[i];
43 else if (c > ' ' && c < 127)
49 /* Reserve space for appending "/". */
50 cp = kzalloc(len + 10, GFP_NOFS);
55 for (i = 0; i < str_len; i++) {
56 const unsigned char c = p[i];
61 } else if (c > ' ' && c < 127) {
65 *cp++ = (c >> 6) + '0';
66 *cp++ = ((c >> 3) & 7) + '0';
67 *cp++ = (c & 7) + '0';
74 * tomoyo_encode - Encode binary string to ascii string.
76 * @str: String in binary format.
78 * Returns pointer to @str in ascii format on success, NULL otherwise.
80 * This function uses kzalloc(), so caller must kfree() if this function
83 char *tomoyo_encode(const char *str)
85 return str ? tomoyo_encode2(str, strlen(str)) : NULL;
89 * tomoyo_get_absolute_path - Get the path of a dentry but ignores chroot'ed root.
91 * @path: Pointer to "struct path".
92 * @buffer: Pointer to buffer to return value in.
93 * @buflen: Sizeof @buffer.
95 * Returns the buffer on success, an error code otherwise.
97 * If dentry is a directory, trailing '/' is appended.
99 static char *tomoyo_get_absolute_path(struct path *path, char * const buffer,
102 char *pos = ERR_PTR(-ENOMEM);
104 struct path ns_root = { };
105 /* go to whatever namespace root we are under */
106 pos = __d_path(path, &ns_root, buffer, buflen - 1);
107 if (!IS_ERR(pos) && *pos == '/' && pos[1]) {
108 struct inode *inode = path->dentry->d_inode;
109 if (inode && S_ISDIR(inode->i_mode)) {
110 buffer[buflen - 2] = '/';
111 buffer[buflen - 1] = '\0';
119 * tomoyo_get_dentry_path - Get the path of a dentry.
121 * @dentry: Pointer to "struct dentry".
122 * @buffer: Pointer to buffer to return value in.
123 * @buflen: Sizeof @buffer.
125 * Returns the buffer on success, an error code otherwise.
127 * If dentry is a directory, trailing '/' is appended.
129 static char *tomoyo_get_dentry_path(struct dentry *dentry, char * const buffer,
132 char *pos = ERR_PTR(-ENOMEM);
134 pos = dentry_path_raw(dentry, buffer, buflen - 1);
135 if (!IS_ERR(pos) && *pos == '/' && pos[1]) {
136 struct inode *inode = dentry->d_inode;
137 if (inode && S_ISDIR(inode->i_mode)) {
138 buffer[buflen - 2] = '/';
139 buffer[buflen - 1] = '\0';
147 * tomoyo_get_local_path - Get the path of a dentry.
149 * @dentry: Pointer to "struct dentry".
150 * @buffer: Pointer to buffer to return value in.
151 * @buflen: Sizeof @buffer.
153 * Returns the buffer on success, an error code otherwise.
155 static char *tomoyo_get_local_path(struct dentry *dentry, char * const buffer,
158 struct super_block *sb = dentry->d_sb;
159 char *pos = tomoyo_get_dentry_path(dentry, buffer, buflen);
162 /* Convert from $PID to self if $PID is current thread. */
163 if (sb->s_magic == PROC_SUPER_MAGIC && *pos == '/') {
165 const pid_t pid = (pid_t) simple_strtoul(pos + 1, &ep, 10);
166 if (*ep == '/' && pid && pid ==
167 task_tgid_nr_ns(current, sb->s_fs_info)) {
171 memmove(pos, "/self", 5);
173 goto prepend_filesystem_name;
175 /* Use filesystem name for unnamed devices. */
176 if (!MAJOR(sb->s_dev))
177 goto prepend_filesystem_name;
179 struct inode *inode = sb->s_root->d_inode;
181 * Use filesystem name if filesystem does not support rename()
184 if (inode->i_op && !inode->i_op->rename)
185 goto prepend_filesystem_name;
187 /* Prepend device name. */
191 const dev_t dev = sb->s_dev;
192 name[sizeof(name) - 1] = '\0';
193 snprintf(name, sizeof(name) - 1, "dev(%u,%u):", MAJOR(dev),
195 name_len = strlen(name);
199 memmove(pos, name, name_len);
202 /* Prepend filesystem name. */
203 prepend_filesystem_name:
205 const char *name = sb->s_type->name;
206 const int name_len = strlen(name);
210 memmove(pos, name, name_len);
215 return ERR_PTR(-ENOMEM);
219 * tomoyo_get_socket_name - Get the name of a socket.
221 * @path: Pointer to "struct path".
222 * @buffer: Pointer to buffer to return value in.
223 * @buflen: Sizeof @buffer.
225 * Returns the buffer.
227 static char *tomoyo_get_socket_name(struct path *path, char * const buffer,
230 struct inode *inode = path->dentry->d_inode;
231 struct socket *sock = inode ? SOCKET_I(inode) : NULL;
232 struct sock *sk = sock ? sock->sk : NULL;
234 snprintf(buffer, buflen, "socket:[family=%u:type=%u:"
235 "protocol=%u]", sk->sk_family, sk->sk_type,
238 snprintf(buffer, buflen, "socket:[unknown]");
244 * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root.
246 * @path: Pointer to "struct path".
248 * Returns the realpath of the given @path on success, NULL otherwise.
250 * If dentry is a directory, trailing '/' is appended.
251 * Characters out of 0x20 < c < 0x7F range are converted to
252 * \ooo style octal string.
253 * Character \ is converted to \\ string.
255 * These functions use kzalloc(), so the caller must call kfree()
256 * if these functions didn't return NULL.
258 char *tomoyo_realpath_from_path(struct path *path)
262 unsigned int buf_len = PAGE_SIZE / 2;
263 struct dentry *dentry = path->dentry;
264 struct super_block *sb;
273 buf = kmalloc(buf_len, GFP_NOFS);
276 /* To make sure that pos is '\0' terminated. */
277 buf[buf_len - 1] = '\0';
278 /* Get better name for socket. */
279 if (sb->s_magic == SOCKFS_MAGIC) {
280 pos = tomoyo_get_socket_name(path, buf, buf_len - 1);
283 /* For "pipe:[\$]". */
284 if (dentry->d_op && dentry->d_op->d_dname) {
285 pos = dentry->d_op->d_dname(dentry, buf, buf_len - 1);
288 inode = sb->s_root->d_inode;
290 * Get local name for filesystems without rename() operation
291 * or dentry without vfsmount.
293 if (!path->mnt || (inode->i_op && !inode->i_op->rename))
294 pos = tomoyo_get_local_path(path->dentry, buf,
296 /* Get absolute name for the rest. */
298 pos = tomoyo_get_absolute_path(path, buf, buf_len - 1);
302 name = tomoyo_encode(pos);
307 tomoyo_warn_oom(__func__);
312 * tomoyo_realpath_nofollow - Get realpath of a pathname.
314 * @pathname: The pathname to solve.
316 * Returns the realpath of @pathname on success, NULL otherwise.
318 char *tomoyo_realpath_nofollow(const char *pathname)
322 if (pathname && kern_path(pathname, 0, &path) == 0) {
323 char *buf = tomoyo_realpath_from_path(&path);