![Tetsuo Handa](/assets/img/avatar_default.png)
Use stack memory for pending entry to reduce kmalloc() which will be kfree()d. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
380 lines
9.5 KiB
C
380 lines
9.5 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 <linux/hash.h>
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#include <linux/magic.h>
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#include <linux/slab.h>
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#include "common.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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struct path ns_root = {.mnt = NULL, .dentry = NULL};
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spin_lock(&dcache_lock);
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/* go to whatever namespace root we are under */
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sp = __d_path(path, &ns_root, newname, newname_len);
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spin_unlock(&dcache_lock);
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/* Prepend "/proc" prefix if using internal proc vfs mount. */
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if (!IS_ERR(sp) && (path->mnt->mnt_flags & MNT_INTERNAL) &&
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(path->mnt->mnt_sb->s_magic == PROC_SUPER_MAGIC)) {
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sp -= 5;
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if (sp >= newname)
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memcpy(sp, "/proc", 5);
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else
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sp = ERR_PTR(-ENOMEM);
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}
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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 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(struct path *path)
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{
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char *buf = kzalloc(sizeof(struct tomoyo_page_buffer), GFP_NOFS);
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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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kfree(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 atomic_t tomoyo_policy_memory_size;
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/* Quota for holding policy. */
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static unsigned int tomoyo_quota_for_policy;
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/**
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* tomoyo_memory_ok - Check memory quota.
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*
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* @ptr: Pointer to allocated memory.
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*
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* Returns true on success, false otherwise.
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*
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* Caller holds tomoyo_policy_lock.
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* Memory pointed by @ptr will be zeroed on success.
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*/
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bool tomoyo_memory_ok(void *ptr)
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{
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int allocated_len = ptr ? ksize(ptr) : 0;
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atomic_add(allocated_len, &tomoyo_policy_memory_size);
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if (ptr && (!tomoyo_quota_for_policy ||
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atomic_read(&tomoyo_policy_memory_size)
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<= tomoyo_quota_for_policy)) {
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memset(ptr, 0, allocated_len);
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return true;
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}
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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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return false;
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}
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/**
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* tomoyo_commit_ok - Check memory quota.
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*
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* @data: Data to copy from.
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* @size: Size in byte.
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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_commit_ok(void *data, const unsigned int size)
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{
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void *ptr = kzalloc(size, GFP_NOFS);
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if (tomoyo_memory_ok(ptr)) {
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memmove(ptr, data, size);
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memset(data, 0, size);
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return ptr;
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}
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return NULL;
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}
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/**
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* tomoyo_memory_free - Free memory for elements.
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*
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* @ptr: Pointer to allocated memory.
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*/
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void tomoyo_memory_free(void *ptr)
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{
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atomic_sub(ksize(ptr), &tomoyo_policy_memory_size);
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kfree(ptr);
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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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struct list_head tomoyo_name_list[TOMOYO_MAX_HASH];
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/**
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* tomoyo_get_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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const struct tomoyo_path_info *tomoyo_get_name(const char *name)
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{
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struct tomoyo_name_entry *ptr;
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unsigned int hash;
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int len;
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int allocated_len;
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struct list_head *head;
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if (!name)
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return NULL;
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len = strlen(name) + 1;
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hash = full_name_hash((const unsigned char *) name, len - 1);
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head = &tomoyo_name_list[hash_long(hash, TOMOYO_HASH_BITS)];
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if (mutex_lock_interruptible(&tomoyo_policy_lock))
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return NULL;
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list_for_each_entry(ptr, head, list) {
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if (hash != ptr->entry.hash || strcmp(name, ptr->entry.name))
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continue;
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atomic_inc(&ptr->users);
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goto out;
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}
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ptr = kzalloc(sizeof(*ptr) + len, GFP_NOFS);
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allocated_len = ptr ? ksize(ptr) : 0;
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if (!ptr || (tomoyo_quota_for_policy &&
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atomic_read(&tomoyo_policy_memory_size) + allocated_len
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> tomoyo_quota_for_policy)) {
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kfree(ptr);
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printk(KERN_WARNING "ERROR: Out of memory "
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"for tomoyo_get_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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atomic_add(allocated_len, &tomoyo_policy_memory_size);
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ptr->entry.name = ((char *) ptr) + sizeof(*ptr);
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memmove((char *) ptr->entry.name, name, len);
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atomic_set(&ptr->users, 1);
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tomoyo_fill_path_info(&ptr->entry);
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list_add_tail(&ptr->list, head);
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out:
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mutex_unlock(&tomoyo_policy_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_get_name(TOMOYO_ROOT_NAME);
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/*
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* tomoyo_read_lock() is not needed because this function is
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* called before the first "delete" request.
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*/
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list_add_tail_rcu(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
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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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}
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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 policy
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= atomic_read(&tomoyo_policy_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_policy)
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snprintf(buffer, sizeof(buffer) - 1,
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" (Quota: %10u)",
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tomoyo_quota_for_policy);
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else
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buffer[0] = '\0';
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tomoyo_io_printf(head, "Policy: %10u%s\n", policy, buffer);
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tomoyo_io_printf(head, "Total: %10u\n", policy);
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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, "Policy: %u", &size) == 1)
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tomoyo_quota_for_policy = size;
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return 0;
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}
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