2015-04-11 19:48:01 +08:00
|
|
|
/*
|
|
|
|
* linux/fs/ext4/crypto_policy.c
|
|
|
|
*
|
|
|
|
* Copyright (C) 2015, Google, Inc.
|
|
|
|
*
|
|
|
|
* This contains encryption policy functions for ext4
|
|
|
|
*
|
|
|
|
* Written by Michael Halcrow, 2015.
|
|
|
|
*/
|
|
|
|
|
|
|
|
#include <linux/random.h>
|
|
|
|
#include <linux/string.h>
|
|
|
|
#include <linux/types.h>
|
|
|
|
|
|
|
|
#include "ext4.h"
|
|
|
|
#include "xattr.h"
|
|
|
|
|
|
|
|
static int ext4_inode_has_encryption_context(struct inode *inode)
|
|
|
|
{
|
|
|
|
int res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION,
|
|
|
|
EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, NULL, 0);
|
|
|
|
return (res > 0);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* check whether the policy is consistent with the encryption context
|
|
|
|
* for the inode
|
|
|
|
*/
|
|
|
|
static int ext4_is_encryption_context_consistent_with_policy(
|
|
|
|
struct inode *inode, const struct ext4_encryption_policy *policy)
|
|
|
|
{
|
|
|
|
struct ext4_encryption_context ctx;
|
|
|
|
int res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION,
|
|
|
|
EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
|
|
|
|
sizeof(ctx));
|
|
|
|
if (res != sizeof(ctx))
|
|
|
|
return 0;
|
|
|
|
return (memcmp(ctx.master_key_descriptor, policy->master_key_descriptor,
|
|
|
|
EXT4_KEY_DESCRIPTOR_SIZE) == 0 &&
|
|
|
|
(ctx.contents_encryption_mode ==
|
|
|
|
policy->contents_encryption_mode) &&
|
|
|
|
(ctx.filenames_encryption_mode ==
|
|
|
|
policy->filenames_encryption_mode));
|
|
|
|
}
|
|
|
|
|
|
|
|
static int ext4_create_encryption_context_from_policy(
|
|
|
|
struct inode *inode, const struct ext4_encryption_policy *policy)
|
|
|
|
{
|
|
|
|
struct ext4_encryption_context ctx;
|
|
|
|
int res = 0;
|
|
|
|
|
|
|
|
ctx.format = EXT4_ENCRYPTION_CONTEXT_FORMAT_V1;
|
|
|
|
memcpy(ctx.master_key_descriptor, policy->master_key_descriptor,
|
|
|
|
EXT4_KEY_DESCRIPTOR_SIZE);
|
2015-04-12 12:43:56 +08:00
|
|
|
if (!ext4_valid_contents_enc_mode(policy->contents_encryption_mode)) {
|
|
|
|
printk(KERN_WARNING
|
|
|
|
"%s: Invalid contents encryption mode %d\n", __func__,
|
|
|
|
policy->contents_encryption_mode);
|
|
|
|
res = -EINVAL;
|
|
|
|
goto out;
|
|
|
|
}
|
2015-04-11 19:48:01 +08:00
|
|
|
ctx.contents_encryption_mode = policy->contents_encryption_mode;
|
|
|
|
ctx.filenames_encryption_mode = policy->filenames_encryption_mode;
|
|
|
|
BUILD_BUG_ON(sizeof(ctx.nonce) != EXT4_KEY_DERIVATION_NONCE_SIZE);
|
|
|
|
get_random_bytes(ctx.nonce, EXT4_KEY_DERIVATION_NONCE_SIZE);
|
|
|
|
|
|
|
|
res = ext4_xattr_set(inode, EXT4_XATTR_INDEX_ENCRYPTION,
|
|
|
|
EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
|
|
|
|
sizeof(ctx), 0);
|
2015-04-12 12:43:56 +08:00
|
|
|
out:
|
2015-04-11 19:48:01 +08:00
|
|
|
if (!res)
|
|
|
|
ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
|
|
|
|
return res;
|
|
|
|
}
|
|
|
|
|
|
|
|
int ext4_process_policy(const struct ext4_encryption_policy *policy,
|
|
|
|
struct inode *inode)
|
|
|
|
{
|
|
|
|
if (policy->version != 0)
|
|
|
|
return -EINVAL;
|
|
|
|
|
|
|
|
if (!ext4_inode_has_encryption_context(inode)) {
|
|
|
|
if (!ext4_empty_dir(inode))
|
|
|
|
return -ENOTEMPTY;
|
|
|
|
return ext4_create_encryption_context_from_policy(inode,
|
|
|
|
policy);
|
|
|
|
}
|
|
|
|
|
|
|
|
if (ext4_is_encryption_context_consistent_with_policy(inode, policy))
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
printk(KERN_WARNING "%s: Policy inconsistent with encryption context\n",
|
|
|
|
__func__);
|
|
|
|
return -EINVAL;
|
|
|
|
}
|
|
|
|
|
|
|
|
int ext4_get_policy(struct inode *inode, struct ext4_encryption_policy *policy)
|
|
|
|
{
|
|
|
|
struct ext4_encryption_context ctx;
|
|
|
|
|
|
|
|
int res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION,
|
|
|
|
EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
|
|
|
|
&ctx, sizeof(ctx));
|
|
|
|
if (res != sizeof(ctx))
|
|
|
|
return -ENOENT;
|
|
|
|
if (ctx.format != EXT4_ENCRYPTION_CONTEXT_FORMAT_V1)
|
|
|
|
return -EINVAL;
|
|
|
|
policy->version = 0;
|
|
|
|
policy->contents_encryption_mode = ctx.contents_encryption_mode;
|
|
|
|
policy->filenames_encryption_mode = ctx.filenames_encryption_mode;
|
|
|
|
memcpy(&policy->master_key_descriptor, ctx.master_key_descriptor,
|
|
|
|
EXT4_KEY_DESCRIPTOR_SIZE);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
int ext4_is_child_context_consistent_with_parent(struct inode *parent,
|
|
|
|
struct inode *child)
|
|
|
|
{
|
|
|
|
struct ext4_encryption_context parent_ctx, child_ctx;
|
|
|
|
int res;
|
|
|
|
|
|
|
|
if ((parent == NULL) || (child == NULL)) {
|
|
|
|
pr_err("parent %p child %p\n", parent, child);
|
|
|
|
BUG_ON(1);
|
|
|
|
}
|
|
|
|
/* no restrictions if the parent directory is not encrypted */
|
|
|
|
if (!ext4_encrypted_inode(parent))
|
|
|
|
return 1;
|
|
|
|
res = ext4_xattr_get(parent, EXT4_XATTR_INDEX_ENCRYPTION,
|
|
|
|
EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
|
|
|
|
&parent_ctx, sizeof(parent_ctx));
|
|
|
|
if (res != sizeof(parent_ctx))
|
|
|
|
return 0;
|
|
|
|
/* if the child directory is not encrypted, this is always a problem */
|
|
|
|
if (!ext4_encrypted_inode(child))
|
|
|
|
return 0;
|
|
|
|
res = ext4_xattr_get(child, EXT4_XATTR_INDEX_ENCRYPTION,
|
|
|
|
EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
|
|
|
|
&child_ctx, sizeof(child_ctx));
|
|
|
|
if (res != sizeof(child_ctx))
|
|
|
|
return 0;
|
|
|
|
return (memcmp(parent_ctx.master_key_descriptor,
|
|
|
|
child_ctx.master_key_descriptor,
|
|
|
|
EXT4_KEY_DESCRIPTOR_SIZE) == 0 &&
|
|
|
|
(parent_ctx.contents_encryption_mode ==
|
|
|
|
child_ctx.contents_encryption_mode) &&
|
|
|
|
(parent_ctx.filenames_encryption_mode ==
|
|
|
|
child_ctx.filenames_encryption_mode));
|
|
|
|
}
|
|
|
|
|
|
|
|
/**
|
|
|
|
* ext4_inherit_context() - Sets a child context from its parent
|
|
|
|
* @parent: Parent inode from which the context is inherited.
|
|
|
|
* @child: Child inode that inherits the context from @parent.
|
|
|
|
*
|
|
|
|
* Return: Zero on success, non-zero otherwise
|
|
|
|
*/
|
|
|
|
int ext4_inherit_context(struct inode *parent, struct inode *child)
|
|
|
|
{
|
|
|
|
struct ext4_encryption_context ctx;
|
|
|
|
int res = ext4_xattr_get(parent, EXT4_XATTR_INDEX_ENCRYPTION,
|
|
|
|
EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
|
|
|
|
&ctx, sizeof(ctx));
|
|
|
|
|
|
|
|
if (res != sizeof(ctx))
|
|
|
|
return -ENOENT;
|
|
|
|
|
|
|
|
get_random_bytes(ctx.nonce, EXT4_KEY_DERIVATION_NONCE_SIZE);
|
|
|
|
res = ext4_xattr_set(child, EXT4_XATTR_INDEX_ENCRYPTION,
|
|
|
|
EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
|
|
|
|
sizeof(ctx), 0);
|
|
|
|
if (!res)
|
|
|
|
ext4_set_inode_flag(child, EXT4_INODE_ENCRYPT);
|
|
|
|
return res;
|
|
|
|
}
|