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alistair23-linux/security/tomoyo/mount.c
Tetsuo Handa 17fcfbd9d4 TOMOYO: Add interactive enforcing mode. 
Since the behavior of the system is restricted by policy, we may need to update
policy when you update packages.

We need to update policy in the following cases.

    * The pathname of files has changed.
    * The dependency of files has changed.
    * The access permissions required has increased.

The ideal way to update policy is to rebuild from the scratch using learning
mode. But it is not desirable to change from enforcing mode to other mode if
the system has once entered in production state. Suppose MAC could support
per-application enforcing mode, the MAC becomes useless if an application that
is not running in enforcing mode was cracked. For example, the whole system
becomes vulnerable if only HTTP server application is running in learning mode
to rebuild policy for the application. So, in TOMOYO Linux, updating policy is
done while the system is running in enforcing mode.

This patch implements "interactive enforcing mode" which allows administrators
to judge whether to accept policy violation in enforcing mode or not.
A demo movie is available at http://www.youtube.com/watch?v=b9q1Jo25LPA .

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>
2010-08-02 15:33:38 +10:00

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/*
* security/tomoyo/mount.c
*
* Copyright (C) 2005-2010 NTT DATA CORPORATION
*/
#include <linux/slab.h>
#include "common.h"
/* Keywords for mount restrictions. */
/* Allow to call 'mount --bind /source_dir /dest_dir' */
#define TOMOYO_MOUNT_BIND_KEYWORD "--bind"
/* Allow to call 'mount --move /old_dir /new_dir ' */
#define TOMOYO_MOUNT_MOVE_KEYWORD "--move"
/* Allow to call 'mount -o remount /dir ' */
#define TOMOYO_MOUNT_REMOUNT_KEYWORD "--remount"
/* Allow to call 'mount --make-unbindable /dir' */
#define TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD "--make-unbindable"
/* Allow to call 'mount --make-private /dir' */
#define TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD "--make-private"
/* Allow to call 'mount --make-slave /dir' */
#define TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD "--make-slave"
/* Allow to call 'mount --make-shared /dir' */
#define TOMOYO_MOUNT_MAKE_SHARED_KEYWORD "--make-shared"
/**
* tomoyo_encode2: Encode binary string to ascii string.
*
* @str: String in binary format.
*
* Returns pointer to @str in ascii format on success, NULL otherwise.
*
* This function uses kzalloc(), so caller must kfree() if this function
* didn't return NULL.
*/
static char *tomoyo_encode2(const char *str)
{
int len = 0;
const char *p = str;
char *cp;
char *cp0;
if (!p)
return NULL;
while (*p) {
const unsigned char c = *p++;
if (c == '\\')
len += 2;
else if (c > ' ' && c < 127)
len++;
else
len += 4;
}
len++;
/* Reserve space for appending "/". */
cp = kzalloc(len + 10, GFP_NOFS);
if (!cp)
return NULL;
cp0 = cp;
p = str;
while (*p) {
const unsigned char c = *p++;
if (c == '\\') {
*cp++ = '\\';
*cp++ = '\\';
} else if (c > ' ' && c < 127) {
*cp++ = c;
} else {
*cp++ = '\\';
*cp++ = (c >> 6) + '0';
*cp++ = ((c >> 3) & 7) + '0';
*cp++ = (c & 7) + '0';
}
}
return cp0;
}
/**
* tomoyo_mount_acl2 - Check permission for mount() operation.
*
* @r: Pointer to "struct tomoyo_request_info".
* @dev_name: Name of device file.
* @dir: Pointer to "struct path".
* @type: Name of filesystem type.
* @flags: Mount options.
*
* Returns 0 on success, negative value otherwise.
*
* Caller holds tomoyo_read_lock().
*/
static int tomoyo_mount_acl2(struct tomoyo_request_info *r, char *dev_name,
struct path *dir, char *type, unsigned long flags)
{
struct path path;
struct tomoyo_acl_info *ptr;
struct file_system_type *fstype = NULL;
const char *requested_type = NULL;
const char *requested_dir_name = NULL;
const char *requested_dev_name = NULL;
struct tomoyo_path_info rtype;
struct tomoyo_path_info rdev;
struct tomoyo_path_info rdir;
int need_dev = 0;
int error = -ENOMEM;
/* Get fstype. */
requested_type = tomoyo_encode2(type);
if (!requested_type)
goto out;
rtype.name = requested_type;
tomoyo_fill_path_info(&rtype);
/* Get mount point. */
requested_dir_name = tomoyo_realpath_from_path(dir);
if (!requested_dir_name) {
error = -ENOMEM;
goto out;
}
rdir.name = requested_dir_name;
tomoyo_fill_path_info(&rdir);
/* Compare fs name. */
if (!strcmp(type, TOMOYO_MOUNT_REMOUNT_KEYWORD)) {
/* dev_name is ignored. */
} else if (!strcmp(type, TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD) ||
!strcmp(type, TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD) ||
!strcmp(type, TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD) ||
!strcmp(type, TOMOYO_MOUNT_MAKE_SHARED_KEYWORD)) {
/* dev_name is ignored. */
} else if (!strcmp(type, TOMOYO_MOUNT_BIND_KEYWORD) ||
!strcmp(type, TOMOYO_MOUNT_MOVE_KEYWORD)) {
need_dev = -1; /* dev_name is a directory */
} else {
fstype = get_fs_type(type);
if (!fstype) {
error = -ENODEV;
goto out;
}
if (fstype->fs_flags & FS_REQUIRES_DEV)
/* dev_name is a block device file. */
need_dev = 1;
}
if (need_dev) {
/* Get mount point or device file. */
if (kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
error = -ENOENT;
goto out;
}
requested_dev_name = tomoyo_realpath_from_path(&path);
if (!requested_dev_name) {
error = -ENOENT;
goto out;
}
} else {
/* Map dev_name to "<NULL>" if no dev_name given. */
if (!dev_name)
dev_name = "<NULL>";
requested_dev_name = tomoyo_encode2(dev_name);
if (!requested_dev_name) {
error = -ENOMEM;
goto out;
}
}
rdev.name = requested_dev_name;
tomoyo_fill_path_info(&rdev);
list_for_each_entry_rcu(ptr, &r->domain->acl_info_list, list) {
struct tomoyo_mount_acl *acl;
if (ptr->type != TOMOYO_TYPE_MOUNT_ACL)
continue;
acl = container_of(ptr, struct tomoyo_mount_acl, head);
if (acl->is_deleted ||
!tomoyo_compare_number_union(flags, &acl->flags) ||
!tomoyo_compare_name_union(&rtype, &acl->fs_type) ||
!tomoyo_compare_name_union(&rdir, &acl->dir_name) ||
(need_dev &&
!tomoyo_compare_name_union(&rdev, &acl->dev_name)))
continue;
error = 0;
break;
}
if (error)
error = tomoyo_supervisor(r, TOMOYO_KEYWORD_ALLOW_MOUNT
"%s %s %s 0x%lX\n",
tomoyo_file_pattern(&rdev),
tomoyo_file_pattern(&rdir),
requested_type, flags);
out:
kfree(requested_dev_name);
kfree(requested_dir_name);
if (fstype)
put_filesystem(fstype);
kfree(requested_type);
return error;
}
/**
* tomoyo_mount_acl - Check permission for mount() operation.
*
* @r: Pointer to "struct tomoyo_request_info".
* @dev_name: Name of device file.
* @dir: Pointer to "struct path".
* @type: Name of filesystem type.
* @flags: Mount options.
*
* Returns 0 on success, negative value otherwise.
*
* Caller holds tomoyo_read_lock().
*/
static int tomoyo_mount_acl(struct tomoyo_request_info *r, char *dev_name,
struct path *dir, char *type, unsigned long flags)
{
int error;
error = -EPERM;
if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
flags &= ~MS_MGC_MSK;
switch (flags & (MS_REMOUNT | MS_MOVE | MS_BIND)) {
case MS_REMOUNT:
case MS_MOVE:
case MS_BIND:
case 0:
break;
default:
printk(KERN_WARNING "ERROR: "
"%s%s%sare given for single mount operation.\n",
flags & MS_REMOUNT ? "'remount' " : "",
flags & MS_MOVE ? "'move' " : "",
flags & MS_BIND ? "'bind' " : "");
return -EINVAL;
}
switch (flags & (MS_UNBINDABLE | MS_PRIVATE | MS_SLAVE | MS_SHARED)) {
case MS_UNBINDABLE:
case MS_PRIVATE:
case MS_SLAVE:
case MS_SHARED:
case 0:
break;
default:
printk(KERN_WARNING "ERROR: "
"%s%s%s%sare given for single mount operation.\n",
flags & MS_UNBINDABLE ? "'unbindable' " : "",
flags & MS_PRIVATE ? "'private' " : "",
flags & MS_SLAVE ? "'slave' " : "",
flags & MS_SHARED ? "'shared' " : "");
return -EINVAL;
}
if (flags & MS_REMOUNT)
error = tomoyo_mount_acl(r, dev_name, dir,
TOMOYO_MOUNT_REMOUNT_KEYWORD,
flags & ~MS_REMOUNT);
else if (flags & MS_MOVE)
error = tomoyo_mount_acl(r, dev_name, dir,
TOMOYO_MOUNT_MOVE_KEYWORD,
flags & ~MS_MOVE);
else if (flags & MS_BIND)
error = tomoyo_mount_acl(r, dev_name, dir,
TOMOYO_MOUNT_BIND_KEYWORD,
flags & ~MS_BIND);
else if (flags & MS_UNBINDABLE)
error = tomoyo_mount_acl(r, dev_name, dir,
TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD,
flags & ~MS_UNBINDABLE);
else if (flags & MS_PRIVATE)
error = tomoyo_mount_acl(r, dev_name, dir,
TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD,
flags & ~MS_PRIVATE);
else if (flags & MS_SLAVE)
error = tomoyo_mount_acl(r, dev_name, dir,
TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD,
flags & ~MS_SLAVE);
else if (flags & MS_SHARED)
error = tomoyo_mount_acl(r, dev_name, dir,
TOMOYO_MOUNT_MAKE_SHARED_KEYWORD,
flags & ~MS_SHARED);
else
do {
error = tomoyo_mount_acl2(r, dev_name, dir, type,
flags);
} while (error == TOMOYO_RETRY_REQUEST);
if (r->mode != TOMOYO_CONFIG_ENFORCING)
error = 0;
return error;
}
/**
* tomoyo_mount_permission - Check permission for mount() operation.
*
* @dev_name: Name of device file.
* @path: Pointer to "struct path".
* @type: Name of filesystem type. May be NULL.
* @flags: Mount options.
* @data_page: Optional data. May be NULL.
*
* Returns 0 on success, negative value otherwise.
*/
int tomoyo_mount_permission(char *dev_name, struct path *path, char *type,
unsigned long flags, void *data_page)
{
struct tomoyo_request_info r;
int error;
int idx;
if (tomoyo_init_request_info(&r, NULL) == TOMOYO_CONFIG_DISABLED)
return 0;
if (!type)
type = "<NULL>";
idx = tomoyo_read_lock();
error = tomoyo_mount_acl(&r, dev_name, path, type, flags);
tomoyo_read_unlock(idx);
return error;
}
/**
* tomoyo_write_mount_policy - Write "struct tomoyo_mount_acl" list.
*
* @data: String to parse.
* @domain: Pointer to "struct tomoyo_domain_info".
* @is_delete: True if it is a delete request.
*
* Returns 0 on success, negative value otherwise.
*/
int tomoyo_write_mount_policy(char *data, struct tomoyo_domain_info *domain,
const bool is_delete)
{
struct tomoyo_acl_info *ptr;
struct tomoyo_mount_acl e = { .head.type = TOMOYO_TYPE_MOUNT_ACL };
int error = is_delete ? -ENOENT : -ENOMEM;
char *w[4];
if (!tomoyo_tokenize(data, w, sizeof(w)) || !w[3][0])
return -EINVAL;
if (!tomoyo_parse_name_union(w[0], &e.dev_name) ||
!tomoyo_parse_name_union(w[1], &e.dir_name) ||
!tomoyo_parse_name_union(w[2], &e.fs_type) ||
!tomoyo_parse_number_union(w[3], &e.flags))
goto out;
if (mutex_lock_interruptible(&tomoyo_policy_lock))
goto out;
list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
struct tomoyo_mount_acl *acl =
container_of(ptr, struct tomoyo_mount_acl, head);
if (!tomoyo_is_same_mount_acl(acl, &e))
continue;
acl->is_deleted = is_delete;
error = 0;
break;
}
if (!is_delete && error) {
struct tomoyo_mount_acl *entry =
tomoyo_commit_ok(&e, sizeof(e));
if (entry) {
list_add_tail_rcu(&entry->head.list,
&domain->acl_info_list);
error = 0;
}
}
mutex_unlock(&tomoyo_policy_lock);
out:
tomoyo_put_name_union(&e.dev_name);
tomoyo_put_name_union(&e.dir_name);
tomoyo_put_name_union(&e.fs_type);
tomoyo_put_number_union(&e.flags);
return error;
}
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