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/*
* security/tomoyo/realpath.c
*
* Get the canonicalized absolute pathnames. The basis for TOMOYO.
*
* Copyright (C) 2005-2009 NTT DATA CORPORATION
*
* Version: 2.2.0 2009/04/01
*
*/
#include <linux/types.h>
#include <linux/mount.h>
#include <linux/mnt_namespace.h>
#include <linux/fs_struct.h>
#include "common.h"
#include "realpath.h"
/**
* tomoyo_encode: Convert binary string to ascii string.
*
* @buffer: Buffer for ASCII string.
* @buflen: Size of @buffer.
* @str: Binary string.
*
* Returns 0 on success, -ENOMEM otherwise.
*/
int tomoyo_encode(char *buffer, int buflen, const char *str)
{
while (1) {
const unsigned char c = *(unsigned char *) str++;
if (tomoyo_is_valid(c)) {
if (--buflen <= 0)
break;
*buffer++ = (char) c;
if (c != '\\')
continue;
if (--buflen <= 0)
break;
*buffer++ = (char) c;
continue;
}
if (!c) {
if (--buflen <= 0)
break;
*buffer = '\0';
return 0;
}
buflen -= 4;
if (buflen <= 0)
break;
*buffer++ = '\\';
*buffer++ = (c >> 6) + '0';
*buffer++ = ((c >> 3) & 7) + '0';
*buffer++ = (c & 7) + '0';
}
return -ENOMEM;
}
/**
* tomoyo_realpath_from_path2 - Returns realpath(3) of the given dentry but ignores chroot'ed root.
*
* @path: Pointer to "struct path".
* @newname: Pointer to buffer to return value in.
* @newname_len: Size of @newname.
*
* Returns 0 on success, negative value 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.
*/
int tomoyo_realpath_from_path2(struct path *path, char *newname,
int newname_len)
{
int error = -ENOMEM;
struct dentry *dentry = path->dentry;
char *sp;
if (!dentry || !path->mnt || !newname || newname_len <= 2048)
return -EINVAL;
if (dentry->d_op && dentry->d_op->d_dname) {
/* For "socket:[\$]" and "pipe:[\$]". */
static const int offset = 1536;
sp = dentry->d_op->d_dname(dentry, newname + offset,
newname_len - offset);
} else {
/* Taken from d_namespace_path(). */
struct path root;
struct path ns_root = { };
struct path tmp;
read_lock(¤t->fs->lock);
root = current->fs->root;
path_get(&root);
read_unlock(¤t->fs->lock);
spin_lock(&vfsmount_lock);
if (root.mnt && root.mnt->mnt_ns)
ns_root.mnt = mntget(root.mnt->mnt_ns->root);
if (ns_root.mnt)
ns_root.dentry = dget(ns_root.mnt->mnt_root);
spin_unlock(&vfsmount_lock);
spin_lock(&dcache_lock);
tmp = ns_root;
sp = __d_path(path, &tmp, newname, newname_len);
spin_unlock(&dcache_lock);
path_put(&root);
path_put(&ns_root);
}
if (IS_ERR(sp))
error = PTR_ERR(sp);
else
error = tomoyo_encode(newname, sp - newname, sp);
/* Append trailing '/' if dentry is a directory. */
if (!error && dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)
&& *newname) {
sp = newname + strlen(newname);
if (*(sp - 1) != '/') {
if (sp < newname + newname_len - 4) {
*sp++ = '/';
*sp = '\0';
} else {
error = -ENOMEM;
}
}
}
if (error)
printk(KERN_WARNING "tomoyo_realpath: Pathname too long.\n");
return error;
}
/**
* 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.
*
* These functions use tomoyo_alloc(), so the caller must call tomoyo_free()
* if these functions didn't return NULL.
*/
char *tomoyo_realpath_from_path(struct path *path)
{
char *buf = tomoyo_alloc(sizeof(struct tomoyo_page_buffer));
BUILD_BUG_ON(sizeof(struct tomoyo_page_buffer)
<= TOMOYO_MAX_PATHNAME_LEN - 1);
if (!buf)
return NULL;
if (tomoyo_realpath_from_path2(path, buf,
TOMOYO_MAX_PATHNAME_LEN - 1) == 0)
return buf;
tomoyo_free(buf);
return NULL;
}
/**
* tomoyo_realpath - Get realpath of a pathname.
*
* @pathname: The pathname to solve.
*
* Returns the realpath of @pathname on success, NULL otherwise.
*/
char *tomoyo_realpath(const char *pathname)
{
struct path path;
if (pathname && kern_path(pathname, LOOKUP_FOLLOW, &path) == 0) {
char *buf = tomoyo_realpath_from_path(&path);
path_put(&path);
return buf;
}
return NULL;
}
/**
* 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;
}
/* Memory allocated for non-string data. */
static unsigned int tomoyo_allocated_memory_for_elements;
/* Quota for holding non-string data. */
static unsigned int tomoyo_quota_for_elements;
/**
* tomoyo_alloc_element - Allocate permanent memory for structures.
*
* @size: Size in bytes.
*
* Returns pointer to allocated memory on success, NULL otherwise.
*
* Memory has to be zeroed.
* The RAM is chunked, so NEVER try to kfree() the returned pointer.
*/
void *tomoyo_alloc_element(const unsigned int size)
{
static char *buf;
static DEFINE_MUTEX(lock);
static unsigned int buf_used_len = PATH_MAX;
char *ptr = NULL;
/*Assumes sizeof(void *) >= sizeof(long) is true. */
const unsigned int word_aligned_size
= roundup(size, max(sizeof(void *), sizeof(long)));
if (word_aligned_size > PATH_MAX)
return NULL;
/***** EXCLUSIVE SECTION START *****/
mutex_lock(&lock);
if (buf_used_len + word_aligned_size > PATH_MAX) {
if (!tomoyo_quota_for_elements ||
tomoyo_allocated_memory_for_elements
+ PATH_MAX <= tomoyo_quota_for_elements)
ptr = kzalloc(PATH_MAX, GFP_KERNEL);
if (!ptr) {
printk(KERN_WARNING "ERROR: Out of memory "
"for tomoyo_alloc_element().\n");
if (!tomoyo_policy_loaded)
panic("MAC Initialization failed.\n");
} else {
buf = ptr;
tomoyo_allocated_memory_for_elements += PATH_MAX;
buf_used_len = word_aligned_size;
ptr = buf;
}
} else if (word_aligned_size) {
int i;
ptr = buf + buf_used_len;
buf_used_len += word_aligned_size;
for (i = 0; i < word_aligned_size; i++) {
if (!ptr[i])
continue;
printk(KERN_ERR "WARNING: Reserved memory was tainted! "
"The system might go wrong.\n");
ptr[
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