2 * security/tomoyo/realpath.c
4 * Pathname calculation functions for TOMOYO.
6 * Copyright (C) 2005-2010 NTT DATA CORPORATION
9 #include <linux/types.h>
10 #include <linux/mount.h>
11 #include <linux/mnt_namespace.h>
12 #include <linux/fs_struct.h>
13 #include <linux/magic.h>
14 #include <linux/slab.h>
17 #include "../../fs/internal.h"
20 * tomoyo_encode: Convert binary string to ascii string.
22 * @str: String in binary format.
24 * Returns pointer to @str in ascii format on success, NULL otherwise.
26 * This function uses kzalloc(), so caller must kfree() if this function
29 char *tomoyo_encode(const char *str)
39 const unsigned char c = *p++;
42 else if (c > ' ' && c < 127)
48 /* Reserve space for appending "/". */
49 cp = kzalloc(len + 10, GFP_NOFS);
55 const unsigned char c = *p++;
60 } else if (c > ' ' && c < 127) {
64 *cp++ = (c >> 6) + '0';
65 *cp++ = ((c >> 3) & 7) + '0';
66 *cp++ = (c & 7) + '0';
73 * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root.
75 * @path: Pointer to "struct path".
77 * Returns the realpath of the given @path on success, NULL otherwise.
79 * If dentry is a directory, trailing '/' is appended.
80 * Characters out of 0x20 < c < 0x7F range are converted to
81 * \ooo style octal string.
82 * Character \ is converted to \\ string.
84 * These functions use kzalloc(), so the caller must call kfree()
85 * if these functions didn't return NULL.
87 char *tomoyo_realpath_from_path(struct path *path)
91 unsigned int buf_len = PAGE_SIZE / 2;
92 struct dentry *dentry = path->dentry;
96 is_dir = dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode);
98 struct path ns_root = { .mnt = NULL, .dentry = NULL };
102 buf = kmalloc(buf_len, GFP_NOFS);
105 /* Get better name for socket. */
106 if (dentry->d_sb && dentry->d_sb->s_magic == SOCKFS_MAGIC) {
107 struct inode *inode = dentry->d_inode;
108 struct socket *sock = inode ? SOCKET_I(inode) : NULL;
109 struct sock *sk = sock ? sock->sk : NULL;
111 snprintf(buf, buf_len - 1, "socket:[family=%u:"
112 "type=%u:protocol=%u]", sk->sk_family,
113 sk->sk_type, sk->sk_protocol);
115 snprintf(buf, buf_len - 1, "socket:[unknown]");
117 name = tomoyo_encode(buf);
120 /* For "socket:[\$]" and "pipe:[\$]". */
121 if (dentry->d_op && dentry->d_op->d_dname) {
122 pos = dentry->d_op->d_dname(dentry, buf, buf_len - 1);
125 name = tomoyo_encode(pos);
128 /* If we don't have a vfsmount, we can't calculate. */
131 /* go to whatever namespace root we are under */
132 pos = __d_path(path, &ns_root, buf, buf_len);
133 /* Prepend "/proc" prefix if using internal proc vfs mount. */
134 if (!IS_ERR(pos) && (path->mnt->mnt_flags & MNT_INTERNAL) &&
135 (path->mnt->mnt_sb->s_magic == PROC_SUPER_MAGIC)) {
138 memcpy(pos, "/proc", 5);
140 pos = ERR_PTR(-ENOMEM);
144 name = tomoyo_encode(pos);
149 tomoyo_warn_oom(__func__);
150 else if (is_dir && *name) {
151 /* Append trailing '/' if dentry is a directory. */
152 char *pos = name + strlen(name) - 1;
155 * This is OK because tomoyo_encode() reserves space
164 * tomoyo_realpath_nofollow - Get realpath of a pathname.
166 * @pathname: The pathname to solve.
168 * Returns the realpath of @pathname on success, NULL otherwise.
170 char *tomoyo_realpath_nofollow(const char *pathname)
174 if (pathname && kern_path(pathname, 0, &path) == 0) {
175 char *buf = tomoyo_realpath_from_path(&path);