diff options
Diffstat (limited to 'fs/f2fs/crypto_key.c')
| -rw-r--r-- | fs/f2fs/crypto_key.c | 255 |
1 files changed, 255 insertions, 0 deletions
diff --git a/fs/f2fs/crypto_key.c b/fs/f2fs/crypto_key.c new file mode 100644 index 000000000..95b8f936f --- /dev/null +++ b/fs/f2fs/crypto_key.c @@ -0,0 +1,255 @@ +/* + * 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; + + if (ci->ci_keyring_key) + 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; + 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 = ((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, + 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); +} |