linux/security/tomoyo/realpath.c

380 lines
9.5 KiB
C

/*
* 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 <linux/hash.h>
#include <linux/magic.h>
#include <linux/slab.h>
#include "common.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 {
struct path ns_root = {.mnt = NULL, .dentry = NULL};
spin_lock(&dcache_lock);
/* go to whatever namespace root we are under */
sp = __d_path(path, &ns_root, newname, newname_len);
spin_unlock(&dcache_lock);
/* Prepend "/proc" prefix if using internal proc vfs mount. */
if (!IS_ERR(sp) && (path->mnt->mnt_flags & MNT_INTERNAL) &&
(path->mnt->mnt_sb->s_magic == PROC_SUPER_MAGIC)) {
sp -= 5;
if (sp >= newname)
memcpy(sp, "/proc", 5);
else
sp = ERR_PTR(-ENOMEM);
}
}
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 kzalloc(), so the caller must call kfree()
* if these functions didn't return NULL.
*/
char *tomoyo_realpath_from_path(struct path *path)
{
char *buf = kzalloc(sizeof(struct tomoyo_page_buffer), GFP_NOFS);
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;
kfree(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 atomic_t tomoyo_policy_memory_size;
/* Quota for holding policy. */
static unsigned int tomoyo_quota_for_policy;
/**
* tomoyo_memory_ok - Check memory quota.
*
* @ptr: Pointer to allocated memory.
*
* Returns true on success, false otherwise.
*
* Caller holds tomoyo_policy_lock.
* Memory pointed by @ptr will be zeroed on success.
*/
bool tomoyo_memory_ok(void *ptr)
{
int allocated_len = ptr ? ksize(ptr) : 0;
atomic_add(allocated_len, &tomoyo_policy_memory_size);
if (ptr && (!tomoyo_quota_for_policy ||
atomic_read(&tomoyo_policy_memory_size)
<= tomoyo_quota_for_policy)) {
memset(ptr, 0, allocated_len);
return true;
}
printk(KERN_WARNING "ERROR: Out of memory "
"for tomoyo_alloc_element().\n");
if (!tomoyo_policy_loaded)
panic("MAC Initialization failed.\n");
return false;
}
/**
* tomoyo_commit_ok - Check memory quota.
*
* @data: Data to copy from.
* @size: Size in byte.
*
* Returns pointer to allocated memory on success, NULL otherwise.
*/
void *tomoyo_commit_ok(void *data, const unsigned int size)
{
void *ptr = kzalloc(size, GFP_NOFS);
if (tomoyo_memory_ok(ptr)) {
memmove(ptr, data, size);
memset(data, 0, size);
return ptr;
}
return NULL;
}
/**
* tomoyo_memory_free - Free memory for elements.
*
* @ptr: Pointer to allocated memory.
*/
void tomoyo_memory_free(void *ptr)
{
atomic_sub(ksize(ptr), &tomoyo_policy_memory_size);
kfree(ptr);
}
/*
* tomoyo_name_list is used for holding string data used by TOMOYO.
* Since same string data is likely used for multiple times (e.g.
* "/lib/libc-2.5.so"), TOMOYO shares string data in the form of
* "const struct tomoyo_path_info *".
*/
struct list_head tomoyo_name_list[TOMOYO_MAX_HASH];
/**
* tomoyo_get_name - Allocate permanent memory for string data.
*
* @name: The string to store into the permernent memory.
*
* Returns pointer to "struct tomoyo_path_info" on success, NULL otherwise.
*/
const struct tomoyo_path_info *tomoyo_get_name(const char *name)
{
struct tomoyo_name_entry *ptr;
unsigned int hash;
int len;
int allocated_len;
struct list_head *head;
if (!name)
return NULL;
len = strlen(name) + 1;
hash = full_name_hash((const unsigned char *) name, len - 1);
head = &tomoyo_name_list[hash_long(hash, TOMOYO_HASH_BITS)];
if (mutex_lock_interruptible(&tomoyo_policy_lock))
return NULL;
list_for_each_entry(ptr, head, list) {
if (hash != ptr->entry.hash || strcmp(name, ptr->entry.name))
continue;
atomic_inc(&ptr->users);
goto out;
}
ptr = kzalloc(sizeof(*ptr) + len, GFP_NOFS);
allocated_len = ptr ? ksize(ptr) : 0;
if (!ptr || (tomoyo_quota_for_policy &&
atomic_read(&tomoyo_policy_memory_size) + allocated_len
> tomoyo_quota_for_policy)) {
kfree(ptr);
printk(KERN_WARNING "ERROR: Out of memory "
"for tomoyo_get_name().\n");
if (!tomoyo_policy_loaded)
panic("MAC Initialization failed.\n");
ptr = NULL;
goto out;
}
atomic_add(allocated_len, &tomoyo_policy_memory_size);
ptr->entry.name = ((char *) ptr) + sizeof(*ptr);
memmove((char *) ptr->entry.name, name, len);
atomic_set(&ptr->users, 1);
tomoyo_fill_path_info(&ptr->entry);
list_add_tail(&ptr->list, head);
out:
mutex_unlock(&tomoyo_policy_lock);
return ptr ? &ptr->entry : NULL;
}
/**
* tomoyo_realpath_init - Initialize realpath related code.
*/
void __init tomoyo_realpath_init(void)
{
int i;
BUILD_BUG_ON(TOMOYO_MAX_PATHNAME_LEN > PATH_MAX);
for (i = 0; i < TOMOYO_MAX_HASH; i++)
INIT_LIST_HEAD(&tomoyo_name_list[i]);
INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list);
tomoyo_kernel_domain.domainname = tomoyo_get_name(TOMOYO_ROOT_NAME);
/*
* tomoyo_read_lock() is not needed because this function is
* called before the first "delete" request.
*/
list_add_tail_rcu(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
if (tomoyo_find_domain(TOMOYO_ROOT_NAME) != &tomoyo_kernel_domain)
panic("Can't register tomoyo_kernel_domain");
}
/**
* tomoyo_read_memory_counter - Check for memory usage in bytes.
*
* @head: Pointer to "struct tomoyo_io_buffer".
*
* Returns memory usage.
*/
int tomoyo_read_memory_counter(struct tomoyo_io_buffer *head)
{
if (!head->read_eof) {
const unsigned int policy
= atomic_read(&tomoyo_policy_memory_size);
char buffer[64];
memset(buffer, 0, sizeof(buffer));
if (tomoyo_quota_for_policy)
snprintf(buffer, sizeof(buffer) - 1,
" (Quota: %10u)",
tomoyo_quota_for_policy);
else
buffer[0] = '\0';
tomoyo_io_printf(head, "Policy: %10u%s\n", policy, buffer);
tomoyo_io_printf(head, "Total: %10u\n", policy);
head->read_eof = true;
}
return 0;
}
/**
* tomoyo_write_memory_quota - Set memory quota.
*
* @head: Pointer to "struct tomoyo_io_buffer".
*
* Returns 0.
*/
int tomoyo_write_memory_quota(struct tomoyo_io_buffer *head)
{
char *data = head->write_buf;
unsigned int size;
if (sscanf(data, "Policy: %u", &size) == 1)
tomoyo_quota_for_policy = size;
return 0;
}