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![Tetsuo Handa](/assets/img/avatar_default.png)
This patch adds some descriptions of lists and structures. This patch contains no code changes. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
488 lines
13 KiB
C
488 lines
13 KiB
C
/*
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* security/tomoyo/realpath.c
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*
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* Get the canonicalized absolute pathnames. The basis for TOMOYO.
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*
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* Copyright (C) 2005-2009 NTT DATA CORPORATION
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*
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* Version: 2.2.0 2009/04/01
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*
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*/
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#include <linux/types.h>
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#include <linux/mount.h>
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#include <linux/mnt_namespace.h>
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#include <linux/fs_struct.h>
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#include "common.h"
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#include "realpath.h"
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/**
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* tomoyo_encode: Convert binary string to ascii string.
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*
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* @buffer: Buffer for ASCII string.
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* @buflen: Size of @buffer.
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* @str: Binary string.
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*
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* Returns 0 on success, -ENOMEM otherwise.
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*/
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int tomoyo_encode(char *buffer, int buflen, const char *str)
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{
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while (1) {
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const unsigned char c = *(unsigned char *) str++;
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if (tomoyo_is_valid(c)) {
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if (--buflen <= 0)
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break;
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*buffer++ = (char) c;
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if (c != '\\')
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continue;
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if (--buflen <= 0)
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break;
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*buffer++ = (char) c;
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continue;
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}
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if (!c) {
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if (--buflen <= 0)
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break;
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*buffer = '\0';
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return 0;
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}
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buflen -= 4;
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if (buflen <= 0)
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break;
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*buffer++ = '\\';
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*buffer++ = (c >> 6) + '0';
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*buffer++ = ((c >> 3) & 7) + '0';
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*buffer++ = (c & 7) + '0';
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}
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return -ENOMEM;
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}
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/**
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* tomoyo_realpath_from_path2 - Returns realpath(3) of the given dentry but ignores chroot'ed root.
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*
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* @path: Pointer to "struct path".
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* @newname: Pointer to buffer to return value in.
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* @newname_len: Size of @newname.
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*
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* Returns 0 on success, negative value 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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int tomoyo_realpath_from_path2(struct path *path, char *newname,
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int newname_len)
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{
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int error = -ENOMEM;
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struct dentry *dentry = path->dentry;
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char *sp;
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if (!dentry || !path->mnt || !newname || newname_len <= 2048)
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return -EINVAL;
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if (dentry->d_op && dentry->d_op->d_dname) {
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/* For "socket:[\$]" and "pipe:[\$]". */
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static const int offset = 1536;
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sp = dentry->d_op->d_dname(dentry, newname + offset,
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newname_len - offset);
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} else {
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/* Taken from d_namespace_path(). */
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struct path root;
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struct path ns_root = { };
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struct path tmp;
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read_lock(¤t->fs->lock);
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root = current->fs->root;
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path_get(&root);
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read_unlock(¤t->fs->lock);
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spin_lock(&vfsmount_lock);
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if (root.mnt && root.mnt->mnt_ns)
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ns_root.mnt = mntget(root.mnt->mnt_ns->root);
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if (ns_root.mnt)
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ns_root.dentry = dget(ns_root.mnt->mnt_root);
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spin_unlock(&vfsmount_lock);
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spin_lock(&dcache_lock);
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tmp = ns_root;
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sp = __d_path(path, &tmp, newname, newname_len);
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spin_unlock(&dcache_lock);
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path_put(&root);
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path_put(&ns_root);
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}
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if (IS_ERR(sp))
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error = PTR_ERR(sp);
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else
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error = tomoyo_encode(newname, sp - newname, sp);
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/* Append trailing '/' if dentry is a directory. */
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if (!error && dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)
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&& *newname) {
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sp = newname + strlen(newname);
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if (*(sp - 1) != '/') {
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if (sp < newname + newname_len - 4) {
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*sp++ = '/';
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*sp = '\0';
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} else {
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error = -ENOMEM;
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}
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}
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}
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if (error)
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printk(KERN_WARNING "tomoyo_realpath: Pathname too long.\n");
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return error;
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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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* These functions use tomoyo_alloc(), so the caller must call tomoyo_free()
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* if these functions didn't return NULL.
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*/
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char *tomoyo_realpath_from_path(struct path *path)
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{
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char *buf = tomoyo_alloc(sizeof(struct tomoyo_page_buffer));
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BUILD_BUG_ON(sizeof(struct tomoyo_page_buffer)
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<= TOMOYO_MAX_PATHNAME_LEN - 1);
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if (!buf)
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return NULL;
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if (tomoyo_realpath_from_path2(path, buf,
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TOMOYO_MAX_PATHNAME_LEN - 1) == 0)
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return buf;
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tomoyo_free(buf);
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return NULL;
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}
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/**
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* tomoyo_realpath - 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(const char *pathname)
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{
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struct path path;
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if (pathname && kern_path(pathname, LOOKUP_FOLLOW, &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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/**
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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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/* Memory allocated for non-string data. */
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static unsigned int tomoyo_allocated_memory_for_elements;
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/* Quota for holding non-string data. */
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static unsigned int tomoyo_quota_for_elements;
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/**
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* tomoyo_alloc_element - Allocate permanent memory for structures.
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*
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* @size: Size in bytes.
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*
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* Returns pointer to allocated memory on success, NULL otherwise.
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*
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* Memory has to be zeroed.
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* The RAM is chunked, so NEVER try to kfree() the returned pointer.
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*/
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void *tomoyo_alloc_element(const unsigned int size)
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{
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static char *buf;
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static DEFINE_MUTEX(lock);
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static unsigned int buf_used_len = PATH_MAX;
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char *ptr = NULL;
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/*Assumes sizeof(void *) >= sizeof(long) is true. */
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const unsigned int word_aligned_size
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= roundup(size, max(sizeof(void *), sizeof(long)));
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if (word_aligned_size > PATH_MAX)
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return NULL;
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mutex_lock(&lock);
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if (buf_used_len + word_aligned_size > PATH_MAX) {
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if (!tomoyo_quota_for_elements ||
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tomoyo_allocated_memory_for_elements
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+ PATH_MAX <= tomoyo_quota_for_elements)
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ptr = kzalloc(PATH_MAX, GFP_KERNEL);
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if (!ptr) {
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printk(KERN_WARNING "ERROR: Out of memory "
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"for tomoyo_alloc_element().\n");
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if (!tomoyo_policy_loaded)
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panic("MAC Initialization failed.\n");
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} else {
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buf = ptr;
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tomoyo_allocated_memory_for_elements += PATH_MAX;
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buf_used_len = word_aligned_size;
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ptr = buf;
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}
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} else if (word_aligned_size) {
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int i;
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ptr = buf + buf_used_len;
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buf_used_len += word_aligned_size;
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for (i = 0; i < word_aligned_size; i++) {
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if (!ptr[i])
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continue;
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printk(KERN_ERR "WARNING: Reserved memory was tainted! "
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"The system might go wrong.\n");
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ptr[i] = '\0';
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}
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}
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mutex_unlock(&lock);
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return ptr;
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}
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/* Memory allocated for string data in bytes. */
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static unsigned int tomoyo_allocated_memory_for_savename;
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/* Quota for holding string data in bytes. */
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static unsigned int tomoyo_quota_for_savename;
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/*
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* TOMOYO uses this hash only when appending a string into the string
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* table. Frequency of appending strings is very low. So we don't need
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* large (e.g. 64k) hash size. 256 will be sufficient.
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*/
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#define TOMOYO_MAX_HASH 256
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/*
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* tomoyo_name_entry is a structure which is used for linking
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* "struct tomoyo_path_info" into tomoyo_name_list .
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*
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* Since tomoyo_name_list manages a list of strings which are shared by
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* multiple processes (whereas "struct tomoyo_path_info" inside
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* "struct tomoyo_path_info_with_data" is not shared), a reference counter will
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* be added to "struct tomoyo_name_entry" rather than "struct tomoyo_path_info"
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* when TOMOYO starts supporting garbage collector.
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*/
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struct tomoyo_name_entry {
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struct list_head list;
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struct tomoyo_path_info entry;
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};
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/* Structure for available memory region. */
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struct tomoyo_free_memory_block_list {
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struct list_head list;
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char *ptr; /* Pointer to a free area. */
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int len; /* Length of the area. */
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};
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/*
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* tomoyo_name_list is used for holding string data used by TOMOYO.
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* Since same string data is likely used for multiple times (e.g.
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* "/lib/libc-2.5.so"), TOMOYO shares string data in the form of
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* "const struct tomoyo_path_info *".
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*/
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static struct list_head tomoyo_name_list[TOMOYO_MAX_HASH];
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/**
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* tomoyo_save_name - Allocate permanent memory for string data.
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*
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* @name: The string to store into the permernent memory.
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*
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* Returns pointer to "struct tomoyo_path_info" on success, NULL otherwise.
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*
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* The RAM is shared, so NEVER try to modify or kfree() the returned name.
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*/
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const struct tomoyo_path_info *tomoyo_save_name(const char *name)
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{
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static LIST_HEAD(fmb_list);
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static DEFINE_MUTEX(lock);
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struct tomoyo_name_entry *ptr;
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unsigned int hash;
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/* fmb contains available size in bytes.
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fmb is removed from the fmb_list when fmb->len becomes 0. */
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struct tomoyo_free_memory_block_list *fmb;
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int len;
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char *cp;
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if (!name)
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return NULL;
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len = strlen(name) + 1;
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if (len > TOMOYO_MAX_PATHNAME_LEN) {
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printk(KERN_WARNING "ERROR: Name too long "
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"for tomoyo_save_name().\n");
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return NULL;
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}
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hash = full_name_hash((const unsigned char *) name, len - 1);
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mutex_lock(&lock);
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list_for_each_entry(ptr, &tomoyo_name_list[hash % TOMOYO_MAX_HASH],
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list) {
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if (hash == ptr->entry.hash && !strcmp(name, ptr->entry.name))
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goto out;
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}
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list_for_each_entry(fmb, &fmb_list, list) {
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if (len <= fmb->len)
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goto ready;
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}
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if (!tomoyo_quota_for_savename ||
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tomoyo_allocated_memory_for_savename + PATH_MAX
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<= tomoyo_quota_for_savename)
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cp = kzalloc(PATH_MAX, GFP_KERNEL);
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else
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cp = NULL;
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fmb = kzalloc(sizeof(*fmb), GFP_KERNEL);
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if (!cp || !fmb) {
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kfree(cp);
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kfree(fmb);
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printk(KERN_WARNING "ERROR: Out of memory "
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"for tomoyo_save_name().\n");
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if (!tomoyo_policy_loaded)
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panic("MAC Initialization failed.\n");
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ptr = NULL;
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goto out;
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}
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tomoyo_allocated_memory_for_savename += PATH_MAX;
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list_add(&fmb->list, &fmb_list);
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fmb->ptr = cp;
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fmb->len = PATH_MAX;
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ready:
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ptr = tomoyo_alloc_element(sizeof(*ptr));
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if (!ptr)
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goto out;
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ptr->entry.name = fmb->ptr;
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memmove(fmb->ptr, name, len);
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tomoyo_fill_path_info(&ptr->entry);
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fmb->ptr += len;
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fmb->len -= len;
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list_add_tail(&ptr->list, &tomoyo_name_list[hash % TOMOYO_MAX_HASH]);
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if (fmb->len == 0) {
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list_del(&fmb->list);
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kfree(fmb);
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}
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out:
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mutex_unlock(&lock);
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return ptr ? &ptr->entry : NULL;
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}
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/**
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* tomoyo_realpath_init - Initialize realpath related code.
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*/
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void __init tomoyo_realpath_init(void)
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{
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int i;
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BUILD_BUG_ON(TOMOYO_MAX_PATHNAME_LEN > PATH_MAX);
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for (i = 0; i < TOMOYO_MAX_HASH; i++)
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INIT_LIST_HEAD(&tomoyo_name_list[i]);
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INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list);
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tomoyo_kernel_domain.domainname = tomoyo_save_name(TOMOYO_ROOT_NAME);
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list_add_tail(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
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down_read(&tomoyo_domain_list_lock);
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if (tomoyo_find_domain(TOMOYO_ROOT_NAME) != &tomoyo_kernel_domain)
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panic("Can't register tomoyo_kernel_domain");
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up_read(&tomoyo_domain_list_lock);
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}
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/* Memory allocated for temporary purpose. */
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static atomic_t tomoyo_dynamic_memory_size;
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/**
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* tomoyo_alloc - Allocate memory for temporary purpose.
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*
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* @size: Size in bytes.
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*
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* Returns pointer to allocated memory on success, NULL otherwise.
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*/
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void *tomoyo_alloc(const size_t size)
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{
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void *p = kzalloc(size, GFP_KERNEL);
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if (p)
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atomic_add(ksize(p), &tomoyo_dynamic_memory_size);
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return p;
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}
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/**
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* tomoyo_free - Release memory allocated by tomoyo_alloc().
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*
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* @p: Pointer returned by tomoyo_alloc(). May be NULL.
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*
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* Returns nothing.
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*/
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void tomoyo_free(const void *p)
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{
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if (p) {
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atomic_sub(ksize(p), &tomoyo_dynamic_memory_size);
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kfree(p);
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}
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}
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/**
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* tomoyo_read_memory_counter - Check for memory usage in bytes.
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*
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* @head: Pointer to "struct tomoyo_io_buffer".
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*
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* Returns memory usage.
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*/
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int tomoyo_read_memory_counter(struct tomoyo_io_buffer *head)
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{
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if (!head->read_eof) {
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const unsigned int shared
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= tomoyo_allocated_memory_for_savename;
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const unsigned int private
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= tomoyo_allocated_memory_for_elements;
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const unsigned int dynamic
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= atomic_read(&tomoyo_dynamic_memory_size);
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char buffer[64];
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memset(buffer, 0, sizeof(buffer));
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if (tomoyo_quota_for_savename)
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snprintf(buffer, sizeof(buffer) - 1,
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" (Quota: %10u)",
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tomoyo_quota_for_savename);
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else
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buffer[0] = '\0';
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tomoyo_io_printf(head, "Shared: %10u%s\n", shared, buffer);
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if (tomoyo_quota_for_elements)
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snprintf(buffer, sizeof(buffer) - 1,
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" (Quota: %10u)",
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tomoyo_quota_for_elements);
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else
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buffer[0] = '\0';
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tomoyo_io_printf(head, "Private: %10u%s\n", private, buffer);
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tomoyo_io_printf(head, "Dynamic: %10u\n", dynamic);
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tomoyo_io_printf(head, "Total: %10u\n",
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shared + private + dynamic);
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head->read_eof = true;
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}
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return 0;
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}
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/**
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* tomoyo_write_memory_quota - Set memory quota.
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*
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* @head: Pointer to "struct tomoyo_io_buffer".
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*
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* Returns 0.
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*/
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int tomoyo_write_memory_quota(struct tomoyo_io_buffer *head)
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{
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char *data = head->write_buf;
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unsigned int size;
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if (sscanf(data, "Shared: %u", &size) == 1)
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tomoyo_quota_for_savename = size;
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else if (sscanf(data, "Private: %u", &size) == 1)
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tomoyo_quota_for_elements = size;
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return 0;
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}
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