mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-05 21:36:44 +07:00
27df4b4a1b
Commit 5625f2e326
("TOMOYO: Change pathname for non-rename()able
filesystems.") intended to be applied to filesystems where the content is
not controllable from the userspace (e.g. proc, sysfs, securityfs), based
on an assumption that such filesystems do not support rename() operation.
But it turned out that read-only filesystems also do not support rename()
operation despite the content is controllable from the userspace, and that
commit is annoying TOMOYO users who want to use e.g. squashfs as the root
filesystem due to use of local name which does not start with '/'.
Therefore, based on an assumption that filesystems which require the
device argument upon mount() request is an indication that the content
is controllable from the userspace, do not use local name if a filesystem
does not support rename() operation but requires the device argument upon
mount() request.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jamorris@linux.microsoft.com>
344 lines
8.0 KiB
C
344 lines
8.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* security/tomoyo/realpath.c
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*
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* Copyright (C) 2005-2011 NTT DATA CORPORATION
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*/
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#include "common.h"
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#include <linux/magic.h>
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/**
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* tomoyo_encode2 - Encode binary string to ascii string.
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*
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* @str: String in binary format.
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* @str_len: Size of @str in byte.
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*
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* Returns pointer to @str in ascii format on success, NULL otherwise.
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*
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* This function uses kzalloc(), so caller must kfree() if this function
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* didn't return NULL.
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*/
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char *tomoyo_encode2(const char *str, int str_len)
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{
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int i;
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int len = 0;
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const char *p = str;
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char *cp;
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char *cp0;
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if (!p)
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return NULL;
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for (i = 0; i < str_len; i++) {
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const unsigned char c = p[i];
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if (c == '\\')
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len += 2;
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else if (c > ' ' && c < 127)
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len++;
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else
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len += 4;
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}
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len++;
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/* Reserve space for appending "/". */
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cp = kzalloc(len + 10, GFP_NOFS);
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if (!cp)
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return NULL;
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cp0 = cp;
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p = str;
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for (i = 0; i < str_len; i++) {
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const unsigned char c = p[i];
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if (c == '\\') {
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*cp++ = '\\';
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*cp++ = '\\';
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} else if (c > ' ' && c < 127) {
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*cp++ = c;
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} else {
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*cp++ = '\\';
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*cp++ = (c >> 6) + '0';
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*cp++ = ((c >> 3) & 7) + '0';
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*cp++ = (c & 7) + '0';
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}
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}
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return cp0;
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}
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/**
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* tomoyo_encode - Encode binary string to ascii string.
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*
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* @str: String in binary format.
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*
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* Returns pointer to @str in ascii format on success, NULL otherwise.
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*
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* This function uses kzalloc(), so caller must kfree() if this function
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* didn't return NULL.
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*/
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char *tomoyo_encode(const char *str)
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{
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return str ? tomoyo_encode2(str, strlen(str)) : NULL;
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}
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/**
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* tomoyo_get_absolute_path - Get the path of a dentry but ignores chroot'ed root.
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*
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* @path: Pointer to "struct path".
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* @buffer: Pointer to buffer to return value in.
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* @buflen: Sizeof @buffer.
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*
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* Returns the buffer on success, an error code otherwise.
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*
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* If dentry is a directory, trailing '/' is appended.
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*/
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static char *tomoyo_get_absolute_path(const struct path *path, char * const buffer,
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const int buflen)
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{
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char *pos = ERR_PTR(-ENOMEM);
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if (buflen >= 256) {
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/* go to whatever namespace root we are under */
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pos = d_absolute_path(path, buffer, buflen - 1);
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if (!IS_ERR(pos) && *pos == '/' && pos[1]) {
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struct inode *inode = d_backing_inode(path->dentry);
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if (inode && S_ISDIR(inode->i_mode)) {
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buffer[buflen - 2] = '/';
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buffer[buflen - 1] = '\0';
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}
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}
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}
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return pos;
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}
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/**
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* tomoyo_get_dentry_path - Get the path of a dentry.
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*
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* @dentry: Pointer to "struct dentry".
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* @buffer: Pointer to buffer to return value in.
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* @buflen: Sizeof @buffer.
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*
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* Returns the buffer on success, an error code otherwise.
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*
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* If dentry is a directory, trailing '/' is appended.
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*/
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static char *tomoyo_get_dentry_path(struct dentry *dentry, char * const buffer,
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const int buflen)
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{
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char *pos = ERR_PTR(-ENOMEM);
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if (buflen >= 256) {
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pos = dentry_path_raw(dentry, buffer, buflen - 1);
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if (!IS_ERR(pos) && *pos == '/' && pos[1]) {
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struct inode *inode = d_backing_inode(dentry);
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if (inode && S_ISDIR(inode->i_mode)) {
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buffer[buflen - 2] = '/';
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buffer[buflen - 1] = '\0';
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}
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}
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}
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return pos;
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}
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/**
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* tomoyo_get_local_path - Get the path of a dentry.
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*
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* @dentry: Pointer to "struct dentry".
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* @buffer: Pointer to buffer to return value in.
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* @buflen: Sizeof @buffer.
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*
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* Returns the buffer on success, an error code otherwise.
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*/
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static char *tomoyo_get_local_path(struct dentry *dentry, char * const buffer,
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const int buflen)
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{
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struct super_block *sb = dentry->d_sb;
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char *pos = tomoyo_get_dentry_path(dentry, buffer, buflen);
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if (IS_ERR(pos))
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return pos;
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/* Convert from $PID to self if $PID is current thread. */
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if (sb->s_magic == PROC_SUPER_MAGIC && *pos == '/') {
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char *ep;
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const pid_t pid = (pid_t) simple_strtoul(pos + 1, &ep, 10);
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if (*ep == '/' && pid && pid ==
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task_tgid_nr_ns(current, sb->s_fs_info)) {
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pos = ep - 5;
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if (pos < buffer)
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goto out;
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memmove(pos, "/self", 5);
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}
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goto prepend_filesystem_name;
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}
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/* Use filesystem name for unnamed devices. */
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if (!MAJOR(sb->s_dev))
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goto prepend_filesystem_name;
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{
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struct inode *inode = d_backing_inode(sb->s_root);
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/*
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* Use filesystem name if filesystem does not support rename()
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* operation.
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*/
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if (!inode->i_op->rename)
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goto prepend_filesystem_name;
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}
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/* Prepend device name. */
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{
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char name[64];
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int name_len;
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const dev_t dev = sb->s_dev;
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name[sizeof(name) - 1] = '\0';
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snprintf(name, sizeof(name) - 1, "dev(%u,%u):", MAJOR(dev),
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MINOR(dev));
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name_len = strlen(name);
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pos -= name_len;
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if (pos < buffer)
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goto out;
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memmove(pos, name, name_len);
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return pos;
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}
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/* Prepend filesystem name. */
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prepend_filesystem_name:
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{
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const char *name = sb->s_type->name;
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const int name_len = strlen(name);
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pos -= name_len + 1;
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if (pos < buffer)
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goto out;
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memmove(pos, name, name_len);
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pos[name_len] = ':';
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}
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return pos;
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out:
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return ERR_PTR(-ENOMEM);
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}
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/**
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* tomoyo_get_socket_name - Get the name of a socket.
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*
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* @path: Pointer to "struct path".
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* @buffer: Pointer to buffer to return value in.
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* @buflen: Sizeof @buffer.
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*
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* Returns the buffer.
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*/
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static char *tomoyo_get_socket_name(const struct path *path, char * const buffer,
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const int buflen)
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{
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struct inode *inode = d_backing_inode(path->dentry);
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struct socket *sock = inode ? SOCKET_I(inode) : NULL;
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struct sock *sk = sock ? sock->sk : NULL;
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if (sk) {
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snprintf(buffer, buflen, "socket:[family=%u:type=%u:protocol=%u]",
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sk->sk_family, sk->sk_type, sk->sk_protocol);
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} else {
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snprintf(buffer, buflen, "socket:[unknown]");
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}
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return buffer;
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}
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/**
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* tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root.
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*
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* @path: Pointer to "struct path".
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*
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* Returns the realpath of the given @path on success, NULL otherwise.
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*
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* If dentry is a directory, trailing '/' is appended.
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* Characters out of 0x20 < c < 0x7F range are converted to
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* \ooo style octal string.
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* Character \ is converted to \\ string.
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*
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* These functions use kzalloc(), so the caller must call kfree()
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* if these functions didn't return NULL.
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*/
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char *tomoyo_realpath_from_path(const struct path *path)
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{
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char *buf = NULL;
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char *name = NULL;
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unsigned int buf_len = PAGE_SIZE / 2;
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struct dentry *dentry = path->dentry;
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struct super_block *sb;
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if (!dentry)
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return NULL;
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sb = dentry->d_sb;
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while (1) {
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char *pos;
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struct inode *inode;
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buf_len <<= 1;
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kfree(buf);
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buf = kmalloc(buf_len, GFP_NOFS);
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if (!buf)
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break;
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/* To make sure that pos is '\0' terminated. */
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buf[buf_len - 1] = '\0';
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/* Get better name for socket. */
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if (sb->s_magic == SOCKFS_MAGIC) {
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pos = tomoyo_get_socket_name(path, buf, buf_len - 1);
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goto encode;
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}
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/* For "pipe:[\$]". */
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if (dentry->d_op && dentry->d_op->d_dname) {
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pos = dentry->d_op->d_dname(dentry, buf, buf_len - 1);
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goto encode;
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}
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inode = d_backing_inode(sb->s_root);
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/*
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* Get local name for filesystems without rename() operation
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* or dentry without vfsmount.
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*/
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if (!path->mnt ||
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(!inode->i_op->rename &&
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!(sb->s_type->fs_flags & FS_REQUIRES_DEV)))
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pos = tomoyo_get_local_path(path->dentry, buf,
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buf_len - 1);
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/* Get absolute name for the rest. */
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else {
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pos = tomoyo_get_absolute_path(path, buf, buf_len - 1);
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/*
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* Fall back to local name if absolute name is not
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* available.
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*/
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if (pos == ERR_PTR(-EINVAL))
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pos = tomoyo_get_local_path(path->dentry, buf,
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buf_len - 1);
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}
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encode:
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if (IS_ERR(pos))
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continue;
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name = tomoyo_encode(pos);
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break;
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}
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kfree(buf);
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if (!name)
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tomoyo_warn_oom(__func__);
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return name;
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}
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/**
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* tomoyo_realpath_nofollow - Get realpath of a pathname.
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*
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* @pathname: The pathname to solve.
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*
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* Returns the realpath of @pathname on success, NULL otherwise.
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*/
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char *tomoyo_realpath_nofollow(const char *pathname)
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{
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struct path path;
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if (pathname && kern_path(pathname, 0, &path) == 0) {
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char *buf = tomoyo_realpath_from_path(&path);
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path_put(&path);
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return buf;
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}
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return NULL;
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}
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