v4.19.13 snapshot.
diff --git a/security/tomoyo/realpath.c b/security/tomoyo/realpath.c
new file mode 100644
index 0000000..6ff8c21
--- /dev/null
+++ b/security/tomoyo/realpath.c
@@ -0,0 +1,330 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * security/tomoyo/realpath.c
+ *
+ * Copyright (C) 2005-2011 NTT DATA CORPORATION
+ */
+
+#include "common.h"
+#include <linux/magic.h>
+
+/**
+ * tomoyo_encode2 - Encode binary string to ascii string.
+ *
+ * @str: String in binary format.
+ * @str_len: Size of @str in byte.
+ *
+ * Returns pointer to @str in ascii format on success, NULL otherwise.
+ *
+ * This function uses kzalloc(), so caller must kfree() if this function
+ * didn't return NULL.
+ */
+char *tomoyo_encode2(const char *str, int str_len)
+{
+ int i;
+ int len = 0;
+ const char *p = str;
+ char *cp;
+ char *cp0;
+
+ if (!p)
+ return NULL;
+ for (i = 0; i < str_len; i++) {
+ const unsigned char c = p[i];
+
+ if (c == '\\')
+ len += 2;
+ else if (c > ' ' && c < 127)
+ len++;
+ else
+ len += 4;
+ }
+ len++;
+ /* Reserve space for appending "/". */
+ cp = kzalloc(len + 10, GFP_NOFS);
+ if (!cp)
+ return NULL;
+ cp0 = cp;
+ p = str;
+ for (i = 0; i < str_len; i++) {
+ const unsigned char c = p[i];
+
+ if (c == '\\') {
+ *cp++ = '\\';
+ *cp++ = '\\';
+ } else if (c > ' ' && c < 127) {
+ *cp++ = c;
+ } else {
+ *cp++ = '\\';
+ *cp++ = (c >> 6) + '0';
+ *cp++ = ((c >> 3) & 7) + '0';
+ *cp++ = (c & 7) + '0';
+ }
+ }
+ return cp0;
+}
+
+/**
+ * tomoyo_encode - Encode binary string to ascii string.
+ *
+ * @str: String in binary format.
+ *
+ * Returns pointer to @str in ascii format on success, NULL otherwise.
+ *
+ * This function uses kzalloc(), so caller must kfree() if this function
+ * didn't return NULL.
+ */
+char *tomoyo_encode(const char *str)
+{
+ return str ? tomoyo_encode2(str, strlen(str)) : NULL;
+}
+
+/**
+ * tomoyo_get_absolute_path - Get the path of a dentry but ignores chroot'ed root.
+ *
+ * @path: Pointer to "struct path".
+ * @buffer: Pointer to buffer to return value in.
+ * @buflen: Sizeof @buffer.
+ *
+ * Returns the buffer on success, an error code otherwise.
+ *
+ * If dentry is a directory, trailing '/' is appended.
+ */
+static char *tomoyo_get_absolute_path(const struct path *path, char * const buffer,
+ const int buflen)
+{
+ char *pos = ERR_PTR(-ENOMEM);
+ if (buflen >= 256) {
+ /* go to whatever namespace root we are under */
+ pos = d_absolute_path(path, buffer, buflen - 1);
+ if (!IS_ERR(pos) && *pos == '/' && pos[1]) {
+ struct inode *inode = d_backing_inode(path->dentry);
+ if (inode && S_ISDIR(inode->i_mode)) {
+ buffer[buflen - 2] = '/';
+ buffer[buflen - 1] = '\0';
+ }
+ }
+ }
+ return pos;
+}
+
+/**
+ * tomoyo_get_dentry_path - Get the path of a dentry.
+ *
+ * @dentry: Pointer to "struct dentry".
+ * @buffer: Pointer to buffer to return value in.
+ * @buflen: Sizeof @buffer.
+ *
+ * Returns the buffer on success, an error code otherwise.
+ *
+ * If dentry is a directory, trailing '/' is appended.
+ */
+static char *tomoyo_get_dentry_path(struct dentry *dentry, char * const buffer,
+ const int buflen)
+{
+ char *pos = ERR_PTR(-ENOMEM);
+ if (buflen >= 256) {
+ pos = dentry_path_raw(dentry, buffer, buflen - 1);
+ if (!IS_ERR(pos) && *pos == '/' && pos[1]) {
+ struct inode *inode = d_backing_inode(dentry);
+ if (inode && S_ISDIR(inode->i_mode)) {
+ buffer[buflen - 2] = '/';
+ buffer[buflen - 1] = '\0';
+ }
+ }
+ }
+ return pos;
+}
+
+/**
+ * tomoyo_get_local_path - Get the path of a dentry.
+ *
+ * @dentry: Pointer to "struct dentry".
+ * @buffer: Pointer to buffer to return value in.
+ * @buflen: Sizeof @buffer.
+ *
+ * Returns the buffer on success, an error code otherwise.
+ */
+static char *tomoyo_get_local_path(struct dentry *dentry, char * const buffer,
+ const int buflen)
+{
+ struct super_block *sb = dentry->d_sb;
+ char *pos = tomoyo_get_dentry_path(dentry, buffer, buflen);
+ if (IS_ERR(pos))
+ return pos;
+ /* Convert from $PID to self if $PID is current thread. */
+ if (sb->s_magic == PROC_SUPER_MAGIC && *pos == '/') {
+ char *ep;
+ const pid_t pid = (pid_t) simple_strtoul(pos + 1, &ep, 10);
+ if (*ep == '/' && pid && pid ==
+ task_tgid_nr_ns(current, sb->s_fs_info)) {
+ pos = ep - 5;
+ if (pos < buffer)
+ goto out;
+ memmove(pos, "/self", 5);
+ }
+ goto prepend_filesystem_name;
+ }
+ /* Use filesystem name for unnamed devices. */
+ if (!MAJOR(sb->s_dev))
+ goto prepend_filesystem_name;
+ {
+ struct inode *inode = d_backing_inode(sb->s_root);
+ /*
+ * Use filesystem name if filesystem does not support rename()
+ * operation.
+ */
+ if (!inode->i_op->rename)
+ goto prepend_filesystem_name;
+ }
+ /* Prepend device name. */
+ {
+ char name[64];
+ int name_len;
+ const dev_t dev = sb->s_dev;
+ name[sizeof(name) - 1] = '\0';
+ snprintf(name, sizeof(name) - 1, "dev(%u,%u):", MAJOR(dev),
+ MINOR(dev));
+ name_len = strlen(name);
+ pos -= name_len;
+ if (pos < buffer)
+ goto out;
+ memmove(pos, name, name_len);
+ return pos;
+ }
+ /* Prepend filesystem name. */
+prepend_filesystem_name:
+ {
+ const char *name = sb->s_type->name;
+ const int name_len = strlen(name);
+ pos -= name_len + 1;
+ if (pos < buffer)
+ goto out;
+ memmove(pos, name, name_len);
+ pos[name_len] = ':';
+ }
+ return pos;
+out:
+ return ERR_PTR(-ENOMEM);
+}
+
+/**
+ * tomoyo_get_socket_name - Get the name of a socket.
+ *
+ * @path: Pointer to "struct path".
+ * @buffer: Pointer to buffer to return value in.
+ * @buflen: Sizeof @buffer.
+ *
+ * Returns the buffer.
+ */
+static char *tomoyo_get_socket_name(const struct path *path, char * const buffer,
+ const int buflen)
+{
+ struct inode *inode = d_backing_inode(path->dentry);
+ struct socket *sock = inode ? SOCKET_I(inode) : NULL;
+ struct sock *sk = sock ? sock->sk : NULL;
+ if (sk) {
+ snprintf(buffer, buflen, "socket:[family=%u:type=%u:"
+ "protocol=%u]", sk->sk_family, sk->sk_type,
+ sk->sk_protocol);
+ } else {
+ snprintf(buffer, buflen, "socket:[unknown]");
+ }
+ return buffer;
+}
+
+/**
+ * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root.
+ *
+ * @path: Pointer to "struct path".
+ *
+ * Returns the realpath of the given @path on success, NULL otherwise.
+ *
+ * If dentry is a directory, trailing '/' is appended.
+ * Characters out of 0x20 < c < 0x7F range are converted to
+ * \ooo style octal string.
+ * Character \ is converted to \\ string.
+ *
+ * These functions use kzalloc(), so the caller must call kfree()
+ * if these functions didn't return NULL.
+ */
+char *tomoyo_realpath_from_path(const struct path *path)
+{
+ char *buf = NULL;
+ char *name = NULL;
+ unsigned int buf_len = PAGE_SIZE / 2;
+ struct dentry *dentry = path->dentry;
+ struct super_block *sb;
+ if (!dentry)
+ return NULL;
+ sb = dentry->d_sb;
+ while (1) {
+ char *pos;
+ struct inode *inode;
+ buf_len <<= 1;
+ kfree(buf);
+ buf = kmalloc(buf_len, GFP_NOFS);
+ if (!buf)
+ break;
+ /* To make sure that pos is '\0' terminated. */
+ buf[buf_len - 1] = '\0';
+ /* Get better name for socket. */
+ if (sb->s_magic == SOCKFS_MAGIC) {
+ pos = tomoyo_get_socket_name(path, buf, buf_len - 1);
+ goto encode;
+ }
+ /* For "pipe:[\$]". */
+ if (dentry->d_op && dentry->d_op->d_dname) {
+ pos = dentry->d_op->d_dname(dentry, buf, buf_len - 1);
+ goto encode;
+ }
+ inode = d_backing_inode(sb->s_root);
+ /*
+ * Get local name for filesystems without rename() operation
+ * or dentry without vfsmount.
+ */
+ if (!path->mnt ||
+ (!inode->i_op->rename))
+ pos = tomoyo_get_local_path(path->dentry, buf,
+ buf_len - 1);
+ /* Get absolute name for the rest. */
+ else {
+ pos = tomoyo_get_absolute_path(path, buf, buf_len - 1);
+ /*
+ * Fall back to local name if absolute name is not
+ * available.
+ */
+ if (pos == ERR_PTR(-EINVAL))
+ pos = tomoyo_get_local_path(path->dentry, buf,
+ buf_len - 1);
+ }
+encode:
+ if (IS_ERR(pos))
+ continue;
+ name = tomoyo_encode(pos);
+ break;
+ }
+ kfree(buf);
+ if (!name)
+ tomoyo_warn_oom(__func__);
+ return name;
+}
+
+/**
+ * tomoyo_realpath_nofollow - Get realpath of a pathname.
+ *
+ * @pathname: The pathname to solve.
+ *
+ * Returns the realpath of @pathname on success, NULL otherwise.
+ */
+char *tomoyo_realpath_nofollow(const char *pathname)
+{
+ struct path path;
+
+ if (pathname && kern_path(pathname, 0, &path) == 0) {
+ char *buf = tomoyo_realpath_from_path(&path);
+ path_put(&path);
+ return buf;
+ }
+ return NULL;
+}