Commit f424f664 authored by Jaegeuk Kim's avatar Jaegeuk Kim
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f2fs crypto: add encryption policy and password salt support



This patch adds encryption policy and password salt support through ioctl
implementation.

It adds three ioctls:
 F2FS_IOC_SET_ENCRYPTION_POLICY,
 F2FS_IOC_GET_ENCRYPTION_POLICY,
 F2FS_IOC_GET_ENCRYPTION_PWSALT, which use xattr operations.

Note that, these definition and codes are taken from ext4 crypto support.
For f2fs, xattr operations and on-disk flags for superblock and inode were
changed.
Signed-off-by: default avatarMichael Halcrow <mhalcrow@google.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarIldar Muslukhov <muslukhovi@gmail.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent b93531dd
......@@ -6,3 +6,4 @@ f2fs-$(CONFIG_F2FS_STAT_FS) += debug.o
f2fs-$(CONFIG_F2FS_FS_XATTR) += xattr.o
f2fs-$(CONFIG_F2FS_FS_POSIX_ACL) += acl.o
f2fs-$(CONFIG_F2FS_IO_TRACE) += trace.o
f2fs-$(CONFIG_F2FS_FS_ENCRYPTION) += crypto_policy.o
/*
* copied from linux/fs/ext4/crypto_policy.c
*
* Copyright (C) 2015, Google, Inc.
* Copyright (C) 2015, Motorola Mobility.
*
* This contains encryption policy functions for f2fs with some modifications
* to support f2fs-specific xattr APIs.
*
* Written by Michael Halcrow, 2015.
* Modified by Jaegeuk Kim, 2015.
*/
#include <linux/random.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/f2fs_fs.h>
#include "f2fs.h"
#include "xattr.h"
static int f2fs_inode_has_encryption_context(struct inode *inode)
{
int res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, NULL, 0, NULL);
return (res > 0);
}
/*
* check whether the policy is consistent with the encryption context
* for the inode
*/
static int f2fs_is_encryption_context_consistent_with_policy(
struct inode *inode, const struct f2fs_encryption_policy *policy)
{
struct f2fs_encryption_context ctx;
int res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
sizeof(ctx), NULL);
if (res != sizeof(ctx))
return 0;
return (memcmp(ctx.master_key_descriptor, policy->master_key_descriptor,
F2FS_KEY_DESCRIPTOR_SIZE) == 0 &&
(ctx.flags == policy->flags) &&
(ctx.contents_encryption_mode ==
policy->contents_encryption_mode) &&
(ctx.filenames_encryption_mode ==
policy->filenames_encryption_mode));
}
static int f2fs_create_encryption_context_from_policy(
struct inode *inode, const struct f2fs_encryption_policy *policy)
{
struct f2fs_encryption_context ctx;
ctx.format = F2FS_ENCRYPTION_CONTEXT_FORMAT_V1;
memcpy(ctx.master_key_descriptor, policy->master_key_descriptor,
F2FS_KEY_DESCRIPTOR_SIZE);
if (!f2fs_valid_contents_enc_mode(policy->contents_encryption_mode)) {
printk(KERN_WARNING
"%s: Invalid contents encryption mode %d\n", __func__,
policy->contents_encryption_mode);
return -EINVAL;
}
if (!f2fs_valid_filenames_enc_mode(policy->filenames_encryption_mode)) {
printk(KERN_WARNING
"%s: Invalid filenames encryption mode %d\n", __func__,
policy->filenames_encryption_mode);
return -EINVAL;
}
if (policy->flags & ~F2FS_POLICY_FLAGS_VALID)
return -EINVAL;
ctx.contents_encryption_mode = policy->contents_encryption_mode;
ctx.filenames_encryption_mode = policy->filenames_encryption_mode;
ctx.flags = policy->flags;
BUILD_BUG_ON(sizeof(ctx.nonce) != F2FS_KEY_DERIVATION_NONCE_SIZE);
get_random_bytes(ctx.nonce, F2FS_KEY_DERIVATION_NONCE_SIZE);
return f2fs_setxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
sizeof(ctx), NULL, 0);
}
int f2fs_process_policy(const struct f2fs_encryption_policy *policy,
struct inode *inode)
{
if (policy->version != 0)
return -EINVAL;
if (!f2fs_inode_has_encryption_context(inode)) {
if (!f2fs_empty_dir(inode))
return -ENOTEMPTY;
return f2fs_create_encryption_context_from_policy(inode,
policy);
}
if (f2fs_is_encryption_context_consistent_with_policy(inode, policy))
return 0;
printk(KERN_WARNING "%s: Policy inconsistent with encryption context\n",
__func__);
return -EINVAL;
}
int f2fs_get_policy(struct inode *inode, struct f2fs_encryption_policy *policy)
{
struct f2fs_encryption_context ctx;
int res;
if (!f2fs_encrypted_inode(inode))
return -ENODATA;
res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
F2FS_XATTR_NAME_ENCRYPTION_CONTEXT,
&ctx, sizeof(ctx), NULL);
if (res != sizeof(ctx))
return -ENODATA;
if (ctx.format != F2FS_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;
policy->flags = ctx.flags;
memcpy(&policy->master_key_descriptor, ctx.master_key_descriptor,
F2FS_KEY_DESCRIPTOR_SIZE);
return 0;
}
int f2fs_is_child_context_consistent_with_parent(struct inode *parent,
struct inode *child)
{
struct f2fs_crypt_info *parent_ci, *child_ci;
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 (!f2fs_encrypted_inode(parent))
return 1;
/* if the child directory is not encrypted, this is always a problem */
if (!f2fs_encrypted_inode(child))
return 0;
res = f2fs_get_encryption_info(parent);
if (res)
return 0;
res = f2fs_get_encryption_info(child);
if (res)
return 0;
parent_ci = F2FS_I(parent)->i_crypt_info;
child_ci = F2FS_I(child)->i_crypt_info;
if (!parent_ci && !child_ci)
return 1;
if (!parent_ci || !child_ci)
return 0;
return (memcmp(parent_ci->ci_master_key,
child_ci->ci_master_key,
F2FS_KEY_DESCRIPTOR_SIZE) == 0 &&
(parent_ci->ci_data_mode == child_ci->ci_data_mode) &&
(parent_ci->ci_filename_mode == child_ci->ci_filename_mode) &&
(parent_ci->ci_flags == child_ci->ci_flags));
}
/**
* f2fs_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 f2fs_inherit_context(struct inode *parent, struct inode *child,
struct page *ipage)
{
struct f2fs_encryption_context ctx;
struct f2fs_crypt_info *ci;
int res;
res = f2fs_get_encryption_info(parent);
if (res < 0)
return res;
ci = F2FS_I(parent)->i_crypt_info;
BUG_ON(ci == NULL);
ctx.format = F2FS_ENCRYPTION_CONTEXT_FORMAT_V1;
ctx.contents_encryption_mode = ci->ci_data_mode;
ctx.filenames_encryption_mode = ci->ci_filename_mode;
ctx.flags = ci->ci_flags;
memcpy(ctx.master_key_descriptor, ci->ci_master_key,
F2FS_KEY_DESCRIPTOR_SIZE);
get_random_bytes(ctx.nonce, F2FS_KEY_DERIVATION_NONCE_SIZE);
return f2fs_setxattr(child, F2FS_XATTR_INDEX_ENCRYPTION,
F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
sizeof(ctx), ipage, 0);
}
......@@ -229,6 +229,13 @@ static inline bool __has_cursum_space(struct f2fs_summary_block *sum, int size,
#define F2FS_IOC_RELEASE_VOLATILE_WRITE _IO(F2FS_IOCTL_MAGIC, 4)
#define F2FS_IOC_ABORT_VOLATILE_WRITE _IO(F2FS_IOCTL_MAGIC, 5)
#define F2FS_IOC_SET_ENCRYPTION_POLICY \
_IOR('f', 19, struct f2fs_encryption_policy)
#define F2FS_IOC_GET_ENCRYPTION_PWSALT \
_IOW('f', 20, __u8[16])
#define F2FS_IOC_GET_ENCRYPTION_POLICY \
_IOW('f', 21, struct f2fs_encryption_policy)
/*
* should be same as XFS_IOC_GOINGDOWN.
* Flags for going down operation used by FS_IOC_GOINGDOWN
......@@ -367,6 +374,8 @@ struct f2fs_map_blocks {
#define F2FS_ENCRYPTION_MODE_AES_256_CBC 3
#define F2FS_ENCRYPTION_MODE_AES_256_CTS 4
#include "f2fs_crypto.h"
#define DEF_DIR_LEVEL 0
struct f2fs_inode_info {
......@@ -1946,4 +1955,11 @@ static inline int f2fs_sb_has_crypto(struct super_block *sb)
return 0;
#endif
}
/* crypto_policy.c */
int f2fs_is_child_context_consistent_with_parent(struct inode *,
struct inode *);
int f2fs_inherit_context(struct inode *, struct inode *, struct page *);
int f2fs_process_policy(const struct f2fs_encryption_policy *, struct inode *);
int f2fs_get_policy(struct inode *, struct f2fs_encryption_policy *);
#endif
......@@ -20,6 +20,7 @@
#include <linux/uaccess.h>
#include <linux/mount.h>
#include <linux/pagevec.h>
#include <linux/random.h>
#include "f2fs.h"
#include "node.h"
......@@ -1347,6 +1348,92 @@ static int f2fs_ioc_fitrim(struct file *filp, unsigned long arg)
return 0;
}
static bool uuid_is_nonzero(__u8 u[16])
{
int i;
for (i = 0; i < 16; i++)
if (u[i])
return true;
return false;
}
static int f2fs_ioc_set_encryption_policy(struct file *filp, unsigned long arg)
{
#ifdef CONFIG_F2FS_FS_ENCRYPTION
struct f2fs_encryption_policy policy;
struct inode *inode = file_inode(filp);
if (copy_from_user(&policy, (struct f2fs_encryption_policy __user *)arg,
sizeof(policy)))
return -EFAULT;
if (f2fs_has_inline_data(inode)) {
int ret = f2fs_convert_inline_inode(inode);
if (ret)
return ret;
}
return f2fs_process_policy(&policy, inode);
#else
return -EOPNOTSUPP;
#endif
}
static int f2fs_ioc_get_encryption_policy(struct file *filp, unsigned long arg)
{
#ifdef CONFIG_F2FS_FS_ENCRYPTION
struct f2fs_encryption_policy policy;
struct inode *inode = file_inode(filp);
int err;
err = f2fs_get_policy(inode, &policy);
if (err)
return err;
if (copy_to_user((struct f2fs_encryption_policy __user *)arg, &policy,
sizeof(policy)))
return -EFAULT;
return 0;
#else
return -EOPNOTSUPP;
#endif
}
static int f2fs_ioc_get_encryption_pwsalt(struct file *filp, unsigned long arg)
{
struct inode *inode = file_inode(filp);
struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
int err;
if (!f2fs_sb_has_crypto(inode->i_sb))
return -EOPNOTSUPP;
if (uuid_is_nonzero(sbi->raw_super->encrypt_pw_salt))
goto got_it;
err = mnt_want_write_file(filp);
if (err)
return err;
/* update superblock with uuid */
generate_random_uuid(sbi->raw_super->encrypt_pw_salt);
err = f2fs_commit_super(sbi);
mnt_drop_write_file(filp);
if (err) {
/* undo new data */
memset(sbi->raw_super->encrypt_pw_salt, 0, 16);
return err;
}
got_it:
if (copy_to_user((__u8 __user *)arg, sbi->raw_super->encrypt_pw_salt,
16))
return -EFAULT;
return 0;
}
long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
switch (cmd) {
......@@ -1370,6 +1457,12 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
return f2fs_ioc_shutdown(filp, arg);
case FITRIM:
return f2fs_ioc_fitrim(filp, arg);
case F2FS_IOC_SET_ENCRYPTION_POLICY:
return f2fs_ioc_set_encryption_policy(filp, arg);
case F2FS_IOC_GET_ENCRYPTION_POLICY:
return f2fs_ioc_get_encryption_policy(filp, arg);
case F2FS_IOC_GET_ENCRYPTION_PWSALT:
return f2fs_ioc_get_encryption_pwsalt(filp, arg);
default:
return -ENOTTY;
}
......
......@@ -584,6 +584,9 @@ static int __f2fs_setxattr(struct inode *inode, int index,
inode->i_ctime = CURRENT_TIME;
clear_inode_flag(fi, FI_ACL_MODE);
}
if (index == F2FS_XATTR_INDEX_ENCRYPTION &&
!strcmp(name, F2FS_XATTR_NAME_ENCRYPTION_CONTEXT))
f2fs_set_encrypted_inode(inode);
if (ipage)
update_inode(inode, ipage);
......
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