--- /dev/null
+/*
+ * 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;
+}
+
+static void f2fs_free_crypt_info(struct f2fs_crypt_info *ci)
+{
+ if (!ci)
+ return;
+
+ key_put(ci->ci_keyring_key);
+ crypto_free_ablkcipher(ci->ci_ctfm);
+ kmem_cache_free(f2fs_crypt_info_cachep, ci);
+}
+
+void f2fs_free_encryption_info(struct inode *inode, struct f2fs_crypt_info *ci)
+{
+ struct f2fs_inode_info *fi = F2FS_I(inode);
+ struct f2fs_crypt_info *prev;
+
+ if (ci == NULL)
+ ci = ACCESS_ONCE(fi->i_crypt_info);
+ if (ci == NULL)
+ return;
+ prev = cmpxchg(&fi->i_crypt_info, ci, NULL);
+ if (prev != ci)
+ return;
+
+ f2fs_free_crypt_info(ci);
+}
+
+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;
+ const struct user_key_payload *ukp;
+ struct crypto_ablkcipher *ctfm;
+ const char *cipher_str;
+ char raw_key[F2FS_MAX_KEY_SIZE];
+ char mode;
+ int res;
+
+ res = f2fs_crypto_initialize();
+ if (res)
+ return res;
+retry:
+ crypt_info = ACCESS_ONCE(fi->i_crypt_info);
+ if (crypt_info) {
+ if (!crypt_info->ci_keyring_key ||
+ key_validate(crypt_info->ci_keyring_key) == 0)
+ return 0;
+ f2fs_free_encryption_info(inode, crypt_info);
+ goto retry;
+ }
+
+ 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 = kmem_cache_alloc(f2fs_crypt_info_cachep, 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;
+ crypt_info->ci_keyring_key = NULL;
+ memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor,
+ sizeof(crypt_info->ci_master_key));
+ if (S_ISREG(inode->i_mode))
+ mode = crypt_info->ci_data_mode;
+ else if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
+ mode = crypt_info->ci_filename_mode;
+ else
+ BUG();
+
+ switch (mode) {
+ case F2FS_ENCRYPTION_MODE_AES_256_XTS:
+ cipher_str = "xts(aes)";
+ break;
+ case F2FS_ENCRYPTION_MODE_AES_256_CTS:
+ cipher_str = "cts(cbc(aes))";
+ break;
+ default:
+ printk_once(KERN_WARNING
+ "f2fs: unsupported key mode %d (ino %u)\n",
+ mode, (unsigned) inode->i_ino);
+ res = -ENOKEY;
+ goto out;
+ }
+
+ 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;
+ }
+ crypt_info->ci_keyring_key = keyring_key;
+ BUG_ON(keyring_key->type != &key_type_logon);
+ ukp = user_key_payload(keyring_key);
+ 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,
+ raw_key);
+ if (res)
+ goto out;
+
+ ctfm = crypto_alloc_ablkcipher(cipher_str, 0, 0);
+ if (!ctfm || IS_ERR(ctfm)) {
+ res = ctfm ? PTR_ERR(ctfm) : -ENOMEM;
+ printk(KERN_DEBUG
+ "%s: error %d (inode %u) allocating crypto tfm\n",
+ __func__, res, (unsigned) inode->i_ino);
+ goto out;
+ }
+ crypt_info->ci_ctfm = ctfm;
+ crypto_ablkcipher_clear_flags(ctfm, ~0);
+ crypto_tfm_set_flags(crypto_ablkcipher_tfm(ctfm),
+ CRYPTO_TFM_REQ_WEAK_KEY);
+ res = crypto_ablkcipher_setkey(ctfm, raw_key,
+ f2fs_encryption_key_size(mode));
+ if (res)
+ goto out;
+
+ memzero_explicit(raw_key, sizeof(raw_key));
+ if (cmpxchg(&fi->i_crypt_info, NULL, crypt_info) != NULL) {
+ f2fs_free_crypt_info(crypt_info);
+ goto retry;
+ }
+ return 0;
+
+out:
+ if (res == -ENOKEY && !S_ISREG(inode->i_mode))
+ res = 0;
+
+ f2fs_free_crypt_info(crypt_info);
+ memzero_explicit(raw_key, sizeof(raw_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);
+}
Code Review / kvmfornfv.git / blobdiff