/*
* 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 "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);
/* Prepend "/proc" prefix if using internal proc vfs mount. */
if (!IS_ERR(sp) && (path->mnt->mnt_parent == path->mnt) &&
(strcmp(path->mnt->mnt_sb->s_type->name, "proc") == 0)) {
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 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;
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[i] = '\0';
}
}
mutex_unlock(&lock);
return ptr;
}
/* Memory allocated for string data in bytes. */
static unsigned int tomoyo_allocated_memory_for_savename;
/* Quota for holding string data in bytes. */
static unsigned int tomoyo_quota_for_savename;
/*
* TOMOYO uses this hash only when appending a string into the string
* table. Frequency of appending strings is very low. So we don't need
* large (e.g. 64k) hash size. 256 will be sufficient.
*/
#define TOMOYO_HASH_BITS 8
#define TOMOYO_MAX_HASH (1u<<TOMOYO_HASH_BITS)
/*
* tomoyo_name_entry is a structure which is used for linking
* "struct tomoyo_path_info" into tomoyo_name_list .
*
* Since tomoyo_name_list manages a list of strings which are shared by
* multiple processes (whereas "struct tomoyo_path_info" inside
* "struct tomoyo_path_info_with_data" is not shared), a reference counter will
* be added to "struct tomoyo_name_entry" rather than "struct tomoyo_path_info"
* when TOMOYO starts supporting garbage collector.
*/
struct tomoyo_name_entry {
struct list_head list;
struct tomoyo_path_info entry;
};
/* Structure for available memory region. */
struct tomoyo_free_memory_block_list {
struct list_head list;
char *ptr; /* Pointer to a free area. */
int len; /* Length of the area. */
};
/*
* 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 *".
*/
static struct list_head tomoyo_name_list[TOMOYO_MAX_HASH];
/**
* tomoyo_save_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.
*
* The RAM is shared, so NEVER try to modify or kfree() the returned name.
*/
const struct tomoyo_path_info *tomoyo_save_name(const char *name)
{
static LIST_HEAD(fmb_list);
static DEFINE_MUTEX(lock);
struct tomoyo_name_entry *ptr;
unsigned int hash;
/* fmb contains available size in bytes.
fmb is removed from the fmb_list when fmb->len becomes 0. */
struct tomoyo_free_memory_block_list *fmb;
int len;
char *cp;
struct list_head *head;
if (!name)
return NULL;
len = strlen(name) + 1;
if (len > TOMOYO_MAX_PATHNAME_LEN) {
printk(KERN_WARNING "ERROR: Name too long "
"for tomoyo_save_name().\n");
return NULL;
}
hash = full_name_hash((const unsigned char *) name, len - 1);
head = &tomoyo_name_list[hash_long(hash, TOMOYO_HASH_BITS)];
mutex_lock(&lock);
list_for_each_entry(ptr, head, list) {
if (hash == ptr->entry.hash && !strcmp(name, ptr->entry.name))
goto out;
}
list_for_each_entry(fmb, &fmb_list, list) {
if (len <= fmb->len)
goto ready;
}
if (!tomoyo_quota_for_savename ||
tomoyo_allocated_memory_for_savename + PATH_MAX
<= tomoyo_quota_for_savename)
cp = kzalloc(PATH_MAX, GFP_KERNEL);
else
cp = NULL;
fmb = kzalloc(sizeof(*fmb), GFP_KERNEL);
if (!cp || !fmb) {
kfree(cp);
kfree(fmb);
printk(KERN_WARNING "ERROR: Out of memory "
"for tomoyo_save_name().\n");
if (!tomoyo_policy_loaded)
panic("MAC Initialization failed.\n");
ptr = NULL;
goto out;
}
tomoyo_allocated_memory_for_savename += PATH_MAX;
list_add(&fmb->list, &fmb_list);
fmb->ptr = cp;
fmb->len = PATH_MAX;
ready:
ptr = tomoyo_alloc_element(sizeof(*ptr));
if (!ptr)
goto out;
ptr->entry.name = fmb->ptr;
memmove(fmb->ptr, name, len);
tomoyo_fill_path_info(&ptr->entry);
fmb->ptr += len;
fmb->len -= len;
list_add_tail(&ptr->list, head);
if (fmb->len == 0) {
list_del(&fmb->list);
kfree(fmb);
}
out:
mutex_unlock(&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_save_name(TOMOYO_ROOT_NAME);
list_add_tail(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
down_read(&tomoyo_domain_list_lock);
if (tomoyo_find_domain(TOMOYO_ROOT_NAME) != &tomoyo_kernel_domain)
panic("Can't register tomoyo_kernel_domain");
up_read(&tomoyo_domain_list_lock);
}
/* Memory allocated for temporary purpose. */
static atomic_t tomoyo_dynamic_memory_size;
/**
* tomoyo_alloc - Allocate memory for temporary purpose.
*
* @size: Size in bytes.
*
* Returns pointer to allocated memory on success, NULL otherwise.
*/
void *tomoyo_alloc(const size_t size)
{
void *p = kzalloc(size, GFP_KERNEL);
if (p)
atomic_add(ksize(p), &tomoyo_dynamic_memory_size);
return p;
}
/**
* tomoyo_free - Release memory allocated by tomoyo_alloc().
*
* @p: Pointer returned by tomoyo_alloc(). May be NULL.
*
* Returns nothing.
*/
void tomoyo_free(const void *p)
{
if (p) {
atomic_sub(ksize(p), &tomoyo_dynamic_memory_size);
kfree(p);
}
}
/**
* 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 shared
= tomoyo_allocated_memory_for_savename;
const unsigned int private
= tomoyo_allocated_memory_for_elements;
const unsigned int dynamic
= atomic_read(&tomoyo_dynamic_memory_size);
char buffer[64];
memset(buffer, 0, sizeof(buffer));
if (tomoyo_quota_for_savename)
snprintf(buffer, sizeof(buffer) - 1,
" (Quota: %10u)",
tomoyo_quota_for_savename);
else
buffer[0] = '\0';
tomoyo_io_printf(head, "Shared: %10u%s\n", shared, buffer);
if (tomoyo_quota_for_elements)
snprintf(buffer, sizeof(buffer) - 1,
" (Quota: %10u)",
tomoyo_quota_for_elements);
else
buffer[0] = '\0';
tomoyo_io_printf(head, "Private: %10u%s\n", private, buffer);
tomoyo_io_printf(head, "Dynamic: %10u\n", dynamic);
tomoyo_io_printf(head, "Total: %10u\n",
shared + private + dynamic);
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, "Shared: %u", &size) == 1)
tomoyo_quota_for_savename = size;
else if (sscanf(data, "Private: %u", &size) == 1)
tomoyo_quota_for_elements = size;
return 0;
}
