[PATCH 7/9] fscrypt: support diskcipher

From: boojin.kim
Date: Wed Aug 21 2019 - 02:42:49 EST

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This patch support fscrypt to use diskcipher in a specific crypto mode
(FSCRYPT_MODE_PRIVATE).
Fscrypt allocates diskcipher and sets the key on diskcipher.
Fscrypt doesn't handle additional data encryption when using diskcipher.

Cc: Theodore Y. Ts'o <tytso@xxxxxxx>
Cc: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
Cc: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: Boojin Kim <boojin.kim@xxxxxxxxxxx>
---
fs/buffer.c | 2 ++
fs/crypto/bio.c | 43 ++++++++++++++++++++++++++-----
fs/crypto/fscrypt_private.h | 28 +++++++++++++++++++-
fs/crypto/keysetup.c | 60
+++++++++++++++++++++++++++++++++++++++++--
fs/crypto/keysetup_v1.c | 2 +-
include/linux/fscrypt.h | 19 ++++++++++++++
include/uapi/linux/fscrypt.h | 2 ++
tools/include/uapi/linux/fs.h | 1 +
8 files changed, 147 insertions(+), 10 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 131d39e..a7de079 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3129,6 +3129,8 @@ static int submit_bh_wbc(int op, int op_flags, struct
buffer_head *bh,
wbc_account_cgroup_owner(wbc, bh->b_page, bh->b_size);
}

+ if (bio->bi_opf & REQ_CRYPT)
+ bio->bi_aux_private = bh->b_private;
submit_bio(bio);
return 0;
}
diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
index 82da251..9e4bf9b 100644
--- a/fs/crypto/bio.c
+++ b/fs/crypto/bio.c
@@ -24,6 +24,7 @@
#include <linux/module.h>
#include <linux/bio.h>
#include <linux/namei.h>
+#include <crypto/diskcipher.h>
#include "fscrypt_private.h"

static void __fscrypt_decrypt_bio(struct bio *bio, bool done)
@@ -81,13 +82,19 @@ int fscrypt_zeroout_range(const struct inode *inode,
pgoff_t lblk,
if (!ciphertext_page)
return -ENOMEM;

- while (len--) {
- err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk,
- ZERO_PAGE(0), ciphertext_page,
- blocksize, 0, GFP_NOFS);
- if (err)
- goto errout;
+ if (__fscrypt_disk_encrypted(inode)) {
+ memset(page_address(ciphertext_page), 0, PAGE_SIZE);
+ ciphertext_page->mapping = inode->i_mapping;
+ }

+ while (len--) {
+ if (!__fscrypt_disk_encrypted(inode)) {
+ err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk,
+ ZERO_PAGE(0),
ciphertext_page,
+ blocksize, 0, GFP_NOFS);
+ if (err)
+ goto errout;
+ }
bio = bio_alloc(GFP_NOWAIT, 1);
if (!bio) {
err = -ENOMEM;
@@ -103,6 +110,7 @@ int fscrypt_zeroout_range(const struct inode *inode,
pgoff_t lblk,
err = -EIO;
goto errout;
}
+ fscrypt_set_bio(inode, bio, 0);
err = submit_bio_wait(bio);
if (err == 0 && bio->bi_status)
err = -EIO;
@@ -118,3 +126,26 @@ int fscrypt_zeroout_range(const struct inode *inode,
pgoff_t lblk,
return err;
}
EXPORT_SYMBOL(fscrypt_zeroout_range);
+
+int fscrypt_disk_encrypted(const struct inode *inode)
+{
+ return __fscrypt_disk_encrypted(inode);
+}
+
+void fscrypt_set_bio(const struct inode *inode, struct bio *bio, u64 dun)
+{
+#ifdef CONFIG_CRYPTO_DISKCIPHER
+ if (__fscrypt_disk_encrypted(inode))
+ crypto_diskcipher_set(bio, inode->i_crypt_info->ci_dtfm,
+ inode, dun);
+#endif
+}
+
+void *fscrypt_get_diskcipher(const struct inode *inode)
+{
+#ifdef CONFIG_CRYPTO_DISKCIPHER
+ if (fscrypt_has_encryption_key(inode))
+ return inode->i_crypt_info->ci_dtfm;
+#endif
+ return NULL;
+}
diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index e84efc0..d2b5fb6 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -163,6 +163,10 @@ struct fscrypt_info {
/* The actual crypto transform used for encryption and decryption */
struct crypto_skcipher *ci_ctfm;

+ /* Cipher for inline encryption engine */
+#ifdef CONFIG_CRYPTO_DISKCIPHER
+ struct crypto_diskcipher *ci_dtfm;
+#endif
/*
* Cipher for ESSIV IV generation. Only set for CBC contents
* encryption, otherwise is NULL.
@@ -226,6 +230,10 @@ static inline bool fscrypt_valid_enc_modes(u32
contents_mode,
filenames_mode == FSCRYPT_MODE_ADIANTUM)
return true;

+ if (contents_mode == FSCRYPT_MODE_PRIVATE &&
+ filenames_mode == FSCRYPT_MODE_AES_256_CTS)
+ return true;
+
return false;
}

@@ -438,13 +446,19 @@ extern int __init fscrypt_init_keyring(void);

/* keysetup.c */

+enum cipher_flags {
+ CRYPT_MODE_SKCIPHER,
+ CRYPT_MODE_ESSIV,
+ CRYPT_MODE_DISKCIPHER,
+};
+
struct fscrypt_mode {
const char *friendly_name;
const char *cipher_str;
int keysize;
int ivsize;
bool logged_impl_name;
- bool needs_essiv;
+ enum cipher_flags flags;
};

static inline bool
@@ -453,6 +467,18 @@ fscrypt_mode_supports_direct_key(const struct
fscrypt_mode *mode)
return mode->ivsize >= offsetofend(union fscrypt_iv, nonce);
}

+static inline int __fscrypt_disk_encrypted(const struct inode *inode)
+{
+#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
+#if IS_ENABLED(CONFIG_CRYPTO_DISKCIPHER)
+ if (inode && inode->i_crypt_info)
+ return S_ISREG(inode->i_mode) &&
+ (inode->i_crypt_info->ci_dtfm != NULL);
+#endif
+#endif
+ return 0;
+}
+
extern struct crypto_skcipher *
fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key,
const struct inode *inode);
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
index d71c2d6..06d9609 100644
--- a/fs/crypto/keysetup.c
+++ b/fs/crypto/keysetup.c
@@ -11,6 +11,7 @@
#include <crypto/aes.h>
#include <crypto/sha.h>
#include <crypto/skcipher.h>
+#include <crypto/diskcipher.h>
#include <linux/key.h>

#include "fscrypt_private.h"
@@ -35,7 +36,7 @@ static struct fscrypt_mode available_modes[] = {
.cipher_str = "cbc(aes)",
.keysize = 16,
.ivsize = 16,
- .needs_essiv = true,
+ .flags = CRYPT_MODE_ESSIV,
},
[FSCRYPT_MODE_AES_128_CTS] = {
.friendly_name = "AES-128-CTS-CBC",
@@ -49,6 +50,13 @@ static struct fscrypt_mode available_modes[] = {
.keysize = 32,
.ivsize = 32,
},
+ [FSCRYPT_MODE_PRIVATE] = {
+ .friendly_name = "AES-256-XTS-DISK",
+ .cipher_str = "xts(aes)-disk",
+ .keysize = 64,
+ .ivsize = 16,
+ .flags = CRYPT_MODE_DISKCIPHER,
+ },
};

static struct fscrypt_mode *
@@ -111,6 +119,35 @@ struct crypto_skcipher
*fscrypt_allocate_skcipher(struct fscrypt_mode *mode,
return ERR_PTR(err);
}

+#if defined(CONFIG_CRYPTO_DISKCIPHER)
+/* Create a diskcipher cipher object for the given encryption mode and key
*/
+static struct crypto_diskcipher *fscrypt_allocate_diskcipher(
+ struct fscrypt_mode *mode, const u8 *raw_key,
+ const struct inode *inode)
+{
+ struct crypto_diskcipher *tfm;
+ int err;
+ bool force = (mode->flags == CRYPT_MODE_DISKCIPHER) ? 0 : 1;
+
+ tfm = crypto_alloc_diskcipher(mode->cipher_str, 0, 0, force);
+ if (IS_ERR(tfm)) {
+ fscrypt_warn(inode->i_sb,
+ "error allocating '%s' transform for inode
%lu: %ld",
+ mode->cipher_str, inode->i_ino,
PTR_ERR(tfm));
+ return tfm;
+ }
+ err = crypto_diskcipher_setkey(tfm, raw_key, mode->keysize, 0);
+ if (err)
+ goto err_free_dtfm;
+
+ return tfm;
+
+err_free_dtfm:
+ crypto_free_diskcipher(tfm);
+ return ERR_PTR(err);
+}
+#endif
+
static int derive_essiv_salt(const u8 *key, int keysize, u8 *salt)
{
struct crypto_shash *tfm = READ_ONCE(essiv_hash_tfm);
@@ -187,13 +224,29 @@ int fscrypt_set_derived_key(struct fscrypt_info *ci,
const u8 *derived_key)
struct crypto_skcipher *ctfm;
int err;

+#if defined(CONFIG_CRYPTO_DISKCIPHER)
+ if (S_ISREG(ci->ci_inode->i_mode) &&
+ (mode->flags == CRYPT_MODE_DISKCIPHER)) {
+ ci->ci_dtfm = fscrypt_allocate_diskcipher(mode, derived_key,
+
ci->ci_inode);
+ if (IS_ERR(ci->ci_dtfm)) {
+ fscrypt_warn(ci->ci_inode,
+ "Error allocating Diskcipher: %p",
+ PTR_ERR(ci->ci_dtfm));
+ ci->ci_dtfm = NULL;
+ return -EINVAL;
+ }
+ return 0;
+ }
+#endif
+
ctfm = fscrypt_allocate_skcipher(mode, derived_key, ci->ci_inode);
if (IS_ERR(ctfm))
return PTR_ERR(ctfm);

ci->ci_ctfm = ctfm;

- if (mode->needs_essiv) {
+ if (mode->flags == CRYPT_MODE_ESSIV) {
err = init_essiv_generator(ci, derived_key, mode->keysize);
if (err) {
fscrypt_warn(ci->ci_inode,
@@ -394,6 +447,9 @@ static void put_crypt_info(struct fscrypt_info *ci)
!fscrypt_is_direct_key_policy(&ci->ci_policy)) {
crypto_free_skcipher(ci->ci_ctfm);
crypto_free_cipher(ci->ci_essiv_tfm);
+#if defined(CONFIG_CRYPTO_DISKCIPHER)
+ crypto_free_diskcipher(ci->ci_dtfm);
+#endif
}

key = ci->ci_master_key;
diff --git a/fs/crypto/keysetup_v1.c b/fs/crypto/keysetup_v1.c
index 0727251..22d0330 100644
--- a/fs/crypto/keysetup_v1.c
+++ b/fs/crypto/keysetup_v1.c
@@ -271,7 +271,7 @@ static int setup_v1_file_key_direct(struct fscrypt_info
*ci,
}

/* ESSIV implies 16-byte IVs which implies !DIRECT_KEY */
- if (WARN_ON(mode->needs_essiv))
+ if (WARN_ON(mode->flags == CRYPT_MODE_ESSIV))
return -EINVAL;

dk = fscrypt_get_direct_key(ci, raw_master_key);
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index f622f74..e0f99db 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -274,6 +274,11 @@ static inline void fscrypt_set_ops(struct super_block
*sb,
{
sb->s_cop = s_cop;
}
+
+void fscrypt_set_bio(const struct inode *inode, struct bio *bio, u64 dun);
+void *fscrypt_get_diskcipher(const struct inode *inode);
+int fscrypt_disk_encrypted(const struct inode *inode);
+
#else /* !CONFIG_FS_ENCRYPTION */

static inline bool fscrypt_has_encryption_key(const struct inode *inode)
@@ -556,6 +561,20 @@ static inline void fscrypt_set_ops(struct super_block
*sb,
{
}

+static inline int fscrypt_disk_encrypted(const struct inode *inode)
+{
+ return 0;
+}
+
+static inline void fscrypt_set_bio(const struct inode *inode,
+ struct bio *bio, u64 dun)
+{
+}
+
+static inline void *fscrypt_get_diskcipher(const struct inode *inode)
+{
+ return NULL;
+}
#endif /* !CONFIG_FS_ENCRYPTION */

/**
diff --git a/include/uapi/linux/fscrypt.h b/include/uapi/linux/fscrypt.h
index 39ccfe9..b9978c4 100644
--- a/include/uapi/linux/fscrypt.h
+++ b/include/uapi/linux/fscrypt.h
@@ -25,6 +25,7 @@
#define FSCRYPT_MODE_AES_128_CBC 5
#define FSCRYPT_MODE_AES_128_CTS 6
#define FSCRYPT_MODE_ADIANTUM 9
+#define FSCRYPT_MODE_PRIVATE 127
#define __FSCRYPT_MODE_MAX 9

/*
@@ -173,6 +174,7 @@ struct fscrypt_get_key_status_arg {
#define FS_ENCRYPTION_MODE_SPECK128_256_XTS 7 /* removed */
#define FS_ENCRYPTION_MODE_SPECK128_256_CTS 8 /* removed */
#define FS_ENCRYPTION_MODE_ADIANTUM FSCRYPT_MODE_ADIANTUM
+#define FS_ENCRYPTION_MODE_PRIVATE FSCRYPT_MODE_PRIVATE
#define FS_KEY_DESC_PREFIX FSCRYPT_KEY_DESC_PREFIX
#define FS_KEY_DESC_PREFIX_SIZE FSCRYPT_KEY_DESC_PREFIX_SIZE
#define FS_MAX_KEY_SIZE FSCRYPT_MAX_KEY_SIZE
diff --git a/tools/include/uapi/linux/fs.h b/tools/include/uapi/linux/fs.h
index 2a616aa..dd3566a 100644
--- a/tools/include/uapi/linux/fs.h
+++ b/tools/include/uapi/linux/fs.h
@@ -237,6 +237,7 @@ struct fsxattr {
#define FS_ENCRYPTION_MODE_SPECK128_256_XTS 7 /* Removed, do not use. */
#define FS_ENCRYPTION_MODE_SPECK128_256_CTS 8 /* Removed, do not use. */
#define FS_ENCRYPTION_MODE_ADIANTUM 9
+#define FS_ENCRYPTION_MODE_PRIVATE 127

struct fscrypt_policy {
__u8 version;
--
2.7.4

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