[PATCH 08/18] f2fs crypto: add encryption key management facilities

Jaegeuk Kim
2015-05-09T04:24:57Z

This patch copies from encrypt_key.c in ext4, and modifies for f2fs.

Use GFP_NOFS, since _f2fs_get_encryption_info is called under f2fs_lock_op.

Signed-off-by: Michael Halcrow <mhalcrow@google.com>
Signed-off-by: Ildar Muslukhov <muslukhovi@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
fs/f2fs/Makefile | 2 +-
fs/f2fs/crypto_key.c | 200 ++++++++++++++++++++++++++++++++++++++++++++++++++
fs/f2fs/f2fs.h | 22 ++++++
fs/f2fs/f2fs_crypto.h | 3 +
4 files changed, 226 insertions(+), 1 deletion(-)
create mode 100644 fs/f2fs/crypto_key.c

diff --git a/fs/f2fs/Makefile b/fs/f2fs/Makefile
index a79907b..b08925d 100644
--- a/fs/f2fs/Makefile
+++ b/fs/f2fs/Makefile
@@ -6,4 +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-$(CONFIG_F2FS_FS_ENCRYPTION) += crypto_policy.o crypto.o
+f2fs-$(CONFIG_F2FS_FS_ENCRYPTION) += crypto_policy.o crypto.o crypto_key.o
diff --git a/fs/f2fs/crypto_key.c b/fs/f2fs/crypto_key.c
new file mode 100644
index 0000000..aec7e17
--- /dev/null
+++ b/fs/f2fs/crypto_key.c
@@ -0,0 +1,200 @@
+/*
+ * linux/fs/f2fs/crypto_key.c
+ *
+ * Copied from linux/fs/f2fs/crypto_key.c
+ *
+ * Copyright (C) 2015, Google, Inc.
+ *
+ * This contains encryption key functions for f2fs
+ *
+ * Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.
+ */
+#include <keys/encrypted-type.h>
+#include <keys/user-type.h>
+#include <linux/random.h>
+#include <linux/scatterlist.h>
+#include <uapi/linux/keyctl.h>
+#include <crypto/hash.h>
+#include <linux/f2fs_fs.h>
+
+#include "f2fs.h"
+#include "xattr.h"
+
+static void derive_crypt_complete(struct crypto_async_request *req, int rc)
+{
+ struct f2fs_completion_result *ecr = req->data;
+
+ if (rc == -EINPROGRESS)
+ return;
+
+ ecr->res = rc;
+ complete(&ecr->completion);
+}
+
+/**
+ * f2fs_derive_key_aes() - Derive a key using AES-128-ECB
+ * @deriving_key: Encryption key used for derivatio.
+ * @source_key: Source key to which to apply derivation.
+ * @derived_key: Derived key.
+ *
+ * Return: Zero on success; non-zero otherwise.
+ */
+static int f2fs_derive_key_aes(char deriving_key[F2FS_AES_128_ECB_KEY_SIZE],
+ char source_key[F2FS_AES_256_XTS_KEY_SIZE],
+ char derived_key[F2FS_AES_256_XTS_KEY_SIZE])
+{
+ int res = 0;
+ struct ablkcipher_request *req = NULL;
+ DECLARE_F2FS_COMPLETION_RESULT(ecr);
+ struct scatterlist src_sg, dst_sg;
+ struct crypto_ablkcipher *tfm = crypto_alloc_ablkcipher("ecb(aes)", 0,
+ 0);
+
+ if (IS_ERR(tfm)) {
+ res = PTR_ERR(tfm);
+ tfm = NULL;
+ goto out;
+ }
+ crypto_ablkcipher_set_flags(tfm, CRYPTO_TFM_REQ_WEAK_KEY);
+ req = ablkcipher_request_alloc(tfm, GFP_NOFS);
+ if (!req) {
+ res = -ENOMEM;
+ goto out;
+ }
+ ablkcipher_request_set_callback(req,
+ CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
+ derive_crypt_complete, &ecr);
+ res = crypto_ablkcipher_setkey(tfm, deriving_key,
+ F2FS_AES_128_ECB_KEY_SIZE);
+ if (res < 0)
+ goto out;
+
+ sg_init_one(&src_sg, source_key, F2FS_AES_256_XTS_KEY_SIZE);
+ sg_init_one(&dst_sg, derived_key, F2FS_AES_256_XTS_KEY_SIZE);
+ ablkcipher_request_set_crypt(req, &src_sg, &dst_sg,
+ F2FS_AES_256_XTS_KEY_SIZE, NULL);
+ res = crypto_ablkcipher_encrypt(req);
+ if (res == -EINPROGRESS || res == -EBUSY) {
+ BUG_ON(req->base.data != &ecr);
+ wait_for_completion(&ecr.completion);
+ res = ecr.res;
+ }
+out:
+ if (req)
+ ablkcipher_request_free(req);
+ if (tfm)
+ crypto_free_ablkcipher(tfm);
+ return res;
+}
+
+void f2fs_free_encryption_info(struct inode *inode)
+{
+ struct f2fs_inode_info *fi = F2FS_I(inode);
+ struct f2fs_crypt_info *ci = fi->i_crypt_info;
+
+ if (!ci)
+ return;
+
+ if (ci->ci_keyring_key)
+ key_put(ci->ci_keyring_key);
+ crypto_free_ablkcipher(ci->ci_ctfm);
+ memzero_explicit(&ci->ci_raw, sizeof(ci->ci_raw));
+ kfree(ci);
+ fi->i_crypt_info = NULL;
+}
+
+int _f2fs_get_encryption_info(struct inode *inode)
+{
+ struct f2fs_inode_info *fi = F2FS_I(inode);
+ struct f2fs_crypt_info *crypt_info;
+ char full_key_descriptor[F2FS_KEY_DESC_PREFIX_SIZE +
+ (F2FS_KEY_DESCRIPTOR_SIZE * 2) + 1];
+ struct key *keyring_key = NULL;
+ struct f2fs_encryption_key *master_key;
+ struct f2fs_encryption_context ctx;
+ struct user_key_payload *ukp;
+ int res;
+
+ if (fi->i_crypt_info) {
+ if (!fi->i_crypt_info->ci_keyring_key ||
+ key_validate(fi->i_crypt_info->ci_keyring_key) == 0)
+ return 0;
+ f2fs_free_encryption_info(inode);
+ }
+
+ res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
+ F2FS_XATTR_NAME_ENCRYPTION_CONTEXT,
+ &ctx, sizeof(ctx), NULL);
+ if (res < 0)
+ return res;
+ else if (res != sizeof(ctx))
+ return -EINVAL;
+ res = 0;
+
+ crypt_info = kmalloc(sizeof(struct f2fs_crypt_info), GFP_NOFS);
+ if (!crypt_info)
+ return -ENOMEM;
+
+ crypt_info->ci_flags = ctx.flags;
+ crypt_info->ci_data_mode = ctx.contents_encryption_mode;
+ crypt_info->ci_filename_mode = ctx.filenames_encryption_mode;
+ crypt_info->ci_ctfm = NULL;
+ memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor,
+ sizeof(crypt_info->ci_master_key));
+ if (S_ISREG(inode->i_mode))
+ crypt_info->ci_mode = ctx.contents_encryption_mode;
+ else if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
+ crypt_info->ci_mode = ctx.filenames_encryption_mode;
+ else {
+ printk(KERN_ERR "f2fs crypto: Unsupported inode type.\n");
+ BUG();
+ }
+ crypt_info->ci_size = f2fs_encryption_key_size(crypt_info->ci_mode);
+ BUG_ON(!crypt_info->ci_size);
+
+ memcpy(full_key_descriptor, F2FS_KEY_DESC_PREFIX,
+ F2FS_KEY_DESC_PREFIX_SIZE);
+ sprintf(full_key_descriptor + F2FS_KEY_DESC_PREFIX_SIZE,
+ "%*phN", F2FS_KEY_DESCRIPTOR_SIZE,
+ ctx.master_key_descriptor);
+ full_key_descriptor[F2FS_KEY_DESC_PREFIX_SIZE +
+ (2 * F2FS_KEY_DESCRIPTOR_SIZE)] = '\0';
+ keyring_key = request_key(&key_type_logon, full_key_descriptor, NULL);
+ if (IS_ERR(keyring_key)) {
+ res = PTR_ERR(keyring_key);
+ keyring_key = NULL;
+ goto out;
+ }
+ BUG_ON(keyring_key->type != &key_type_logon);
+ ukp = ((struct user_key_payload *)keyring_key->payload.data);
+ if (ukp->datalen != sizeof(struct f2fs_encryption_key)) {
+ res = -EINVAL;
+ goto out;
+ }
+ master_key = (struct f2fs_encryption_key *)ukp->data;
+ BUILD_BUG_ON(F2FS_AES_128_ECB_KEY_SIZE !=
+ F2FS_KEY_DERIVATION_NONCE_SIZE);
+ BUG_ON(master_key->size != F2FS_AES_256_XTS_KEY_SIZE);
+ res = f2fs_derive_key_aes(ctx.nonce, master_key->raw,
+ crypt_info->ci_raw);
+out:
+ if (res < 0) {
+ if (res == -ENOKEY)
+ res = 0;
+ kfree(crypt_info);
+ } else {
+ fi->i_crypt_info = crypt_info;
+ crypt_info->ci_keyring_key = keyring_key;
+ keyring_key = NULL;
+ }
+ if (keyring_key)
+ key_put(keyring_key);
+ return res;
+}
+
+int f2fs_has_encryption_key(struct inode *inode)
+{
+ struct f2fs_inode_info *fi = F2FS_I(inode);
+
+ return (fi->i_crypt_info != NULL);
+}
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index d586346..ef79ac8 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1973,17 +1973,39 @@ int f2fs_decrypt(struct f2fs_crypto_ctx *, struct page *);
int f2fs_decrypt_one(struct inode *, struct page *);
void f2fs_end_io_crypto_work(struct f2fs_crypto_ctx *, struct bio *);

+/* crypto_key.c */
+void f2fs_free_encryption_info(struct inode *);
+int _f2fs_get_encryption_info(struct inode *inode);
+
#ifdef CONFIG_F2FS_FS_ENCRYPTION
void f2fs_restore_and_release_control_page(struct page **);
void f2fs_restore_control_page(struct page *);

int f2fs_init_crypto(void);
void f2fs_exit_crypto(void);
+
+int f2fs_has_encryption_key(struct inode *);
+
+static inline int f2fs_get_encryption_info(struct inode *inode)
+{
+ struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
+
+ if (!ci ||
+ (ci->ci_keyring_key &&
+ (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) |
+ (1 << KEY_FLAG_REVOKED) |
+ (1 << KEY_FLAG_DEAD)))))
+ return _f2fs_get_encryption_info(inode);
+ return 0;
+}
#else
static inline void f2fs_restore_and_release_control_page(struct page **p) { }
static inline void f2fs_restore_control_page(struct page *p) { }

static inline int f2fs_init_crypto(void) { return 0; }
static inline void f2fs_exit_crypto(void) { }
+
+static inline int f2fs_has_encryption_key(struct inode *i) { return 0; }
+static inline int f2fs_get_encryption_info(struct inode *i) { return 0; }
#endif
#endif
diff --git a/fs/f2fs/f2fs_crypto.h b/fs/f2fs/f2fs_crypto.h
index cfc37c1..bad32e6 100644
--- a/fs/f2fs/f2fs_crypto.h
+++ b/fs/f2fs/f2fs_crypto.h
@@ -65,6 +65,9 @@ struct f2fs_encryption_context {
#define F2FS_AES_256_XTS_KEY_SIZE 64
#define F2FS_MAX_KEY_SIZE 64

+#define F2FS_KEY_DESC_PREFIX "f2fs:"
+#define F2FS_KEY_DESC_PREFIX_SIZE 5
+
struct f2fs_encryption_key {
__u32 mode;
char raw[F2FS_MAX_KEY_SIZE];
--
2.1.1