Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756812AbcCBSfP (ORCPT ); Wed, 2 Mar 2016 13:35:15 -0500 Received: from mail.kernel.org ([198.145.29.136]:48394 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756444AbcCBSb7 (ORCPT ); Wed, 2 Mar 2016 13:31:59 -0500 From: Jaegeuk Kim To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, tytso@mit.edu Cc: Jaegeuk Kim , Michael Halcrow , Ildar Muslukhov Subject: [PATCH 04/10] fs crypto: add keyinfo.c to handle permissions Date: Wed, 2 Mar 2016 10:31:12 -0800 Message-Id: <1456943478-11107-5-git-send-email-jaegeuk@kernel.org> X-Mailer: git-send-email 2.6.3 In-Reply-To: <1456943478-11107-1-git-send-email-jaegeuk@kernel.org> References: <1456943478-11107-1-git-send-email-jaegeuk@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9374 Lines: 333 This patch adds keyinfo.c supporting key management. - fscrypt_get_encryption_info - fscrypt_free_encryption_info Signed-off-by: Michael Halcrow Signed-off-by: Ildar Muslukhov Signed-off-by: Theodore Ts'o Signed-off-by: Jaegeuk Kim --- fs/crypto/keyinfo.c | 278 +++++++++++++++++++++++++++++++++++++++++++++++ include/linux/fscrypto.h | 16 +++ 2 files changed, 294 insertions(+) create mode 100644 fs/crypto/keyinfo.c diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c new file mode 100644 index 0000000..cb61842 --- /dev/null +++ b/fs/crypto/keyinfo.c @@ -0,0 +1,278 @@ +/* + * key management facility for FS encryption support. + * + * Copyright (C) 2015, Google, Inc. + * + * This contains encryption key functions. + * + * Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015. + */ + +#include +#include +#include +#include +#include +#include +#include + +static void derive_crypt_complete(struct crypto_async_request *req, int rc) +{ + struct fscrypt_completion_result *ecr = req->data; + + if (rc == -EINPROGRESS) + return; + + ecr->res = rc; + complete(&ecr->completion); +} + +/** + * derive_key_aes() - Derive a key using AES-128-ECB + * @deriving_key: Encryption key used for derivation. + * @source_key: Source key to which to apply derivation. + * @derived_key: Derived key. + * + * Return: Zero on success; non-zero otherwise. + */ +static int derive_key_aes(u8 deriving_key[FS_AES_128_ECB_KEY_SIZE], + u8 source_key[FS_AES_256_XTS_KEY_SIZE], + u8 derived_key[FS_AES_256_XTS_KEY_SIZE]) +{ + int res = 0; + struct ablkcipher_request *req = NULL; + DECLARE_FS_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, + FS_AES_128_ECB_KEY_SIZE); + if (res < 0) + goto out; + + sg_init_one(&src_sg, source_key, FS_AES_256_XTS_KEY_SIZE); + sg_init_one(&dst_sg, derived_key, FS_AES_256_XTS_KEY_SIZE); + ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, + FS_AES_256_XTS_KEY_SIZE, NULL); + res = crypto_ablkcipher_encrypt(req); + if (res == -EINPROGRESS || res == -EBUSY) { + 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 put_crypt_info(struct fscrypt_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(fscrypt_info_cachep, ci); +} + +int get_crypt_info(struct inode *inode) +{ + struct fscrypt_info *crypt_info; + u8 full_key_descriptor[FS_KEY_DESC_PREFIX_SIZE + + (FS_KEY_DESCRIPTOR_SIZE * 2) + 1]; + struct key *keyring_key = NULL; + struct fscrypt_key *master_key; + struct fscrypt_context ctx; + const struct user_key_payload *ukp; + struct crypto_ablkcipher *ctfm; + const char *cipher_str; + u8 raw_key[FS_MAX_KEY_SIZE]; + u8 mode; + int res; + + res = fscrypt_initialize(); + if (res) + return res; + + if (!inode->i_sb->s_cop->get_context) + return -EOPNOTSUPP; +retry: + crypt_info = ACCESS_ONCE(inode->i_crypt_info); + if (crypt_info) { + if (!crypt_info->ci_keyring_key || + key_validate(crypt_info->ci_keyring_key) == 0) + return 0; + fscrypt_put_encryption_info(inode, crypt_info); + goto retry; + } + + res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); + if (res < 0) { + if (!fscrypt_dummy_context_enabled(inode)) + return res; + ctx.contents_encryption_mode = FS_ENCRYPTION_MODE_AES_256_XTS; + ctx.filenames_encryption_mode = FS_ENCRYPTION_MODE_AES_256_CTS; + ctx.flags = 0; + } else if (res != sizeof(ctx)) { + return -EINVAL; + } + res = 0; + + crypt_info = kmem_cache_alloc(fscrypt_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 FS_ENCRYPTION_MODE_AES_256_XTS: + cipher_str = "xts(aes)"; + break; + case FS_ENCRYPTION_MODE_AES_256_CTS: + cipher_str = "cts(cbc(aes))"; + break; + default: + printk_once(KERN_WARNING + "%s: unsupported key mode %d (ino %u)\n", + __func__, mode, (unsigned) inode->i_ino); + res = -ENOKEY; + goto out; + } + if (fscrypt_dummy_context_enabled(inode)) { + memset(raw_key, 0x42, FS_AES_256_XTS_KEY_SIZE); + goto got_key; + } + memcpy(full_key_descriptor, FS_KEY_DESC_PREFIX, + FS_KEY_DESC_PREFIX_SIZE); + sprintf(full_key_descriptor + FS_KEY_DESC_PREFIX_SIZE, + "%*phN", FS_KEY_DESCRIPTOR_SIZE, + ctx.master_key_descriptor); + full_key_descriptor[FS_KEY_DESC_PREFIX_SIZE + + (2 * FS_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; + if (keyring_key->type != &key_type_logon) { + printk_once(KERN_WARNING + "%s: key type must be logon\n", __func__); + res = -ENOKEY; + goto out; + } + down_read(&keyring_key->sem); + ukp = user_key_payload(keyring_key); + if (ukp->datalen != sizeof(struct fscrypt_key)) { + res = -EINVAL; + up_read(&keyring_key->sem); + goto out; + } + master_key = (struct fscrypt_key *)ukp->data; + BUILD_BUG_ON(FS_AES_128_ECB_KEY_SIZE != FS_KEY_DERIVATION_NONCE_SIZE); + + if (master_key->size != FS_AES_256_XTS_KEY_SIZE) { + printk_once(KERN_WARNING + "%s: key size incorrect: %d\n", + __func__, master_key->size); + res = -ENOKEY; + up_read(&keyring_key->sem); + goto out; + } + res = derive_key_aes(ctx.nonce, master_key->raw, raw_key); + up_read(&keyring_key->sem); + if (res) + goto out; +got_key: + 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, fscrypt_key_size(mode)); + if (res) + goto out; + + memzero_explicit(raw_key, sizeof(raw_key)); + if (cmpxchg(&inode->i_crypt_info, NULL, crypt_info) != NULL) { + put_crypt_info(crypt_info); + goto retry; + } + return 0; + +out: + if (res == -ENOKEY) + res = 0; + put_crypt_info(crypt_info); + memzero_explicit(raw_key, sizeof(raw_key)); + return res; +} + +void fscrypt_put_encryption_info(struct inode *inode, struct fscrypt_info *ci) +{ + struct fscrypt_info *prev; + + if (ci == NULL) + ci = ACCESS_ONCE(inode->i_crypt_info); + if (ci == NULL) + return; + + prev = cmpxchg(&inode->i_crypt_info, ci, NULL); + if (prev != ci) + return; + + put_crypt_info(ci); +} +EXPORT_SYMBOL(fscrypt_put_encryption_info); + +int fscrypt_get_encryption_info(struct inode *inode) +{ + struct fscrypt_info *ci = 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 get_crypt_info(inode); + return 0; +} +EXPORT_SYMBOL(fscrypt_get_encryption_info); diff --git a/include/linux/fscrypto.h b/include/linux/fscrypto.h index 880c81b..0720292 100644 --- a/include/linux/fscrypto.h +++ b/include/linux/fscrypto.h @@ -258,6 +258,10 @@ extern int fscrypt_get_policy(struct inode *, struct fscrypt_policy *); extern int fscrypt_has_permitted_context(struct inode *, struct inode *); extern int fscrypt_inherit_context(struct inode *, struct inode *, void *, bool); +/* keyinfo.c */ +extern int get_crypt_info(struct inode *); +extern int fscrypt_get_encryption_info(struct inode *); +extern void fscrypt_put_encryption_info(struct inode *, struct fscrypt_info *); #endif /* crypto.c */ @@ -328,4 +332,16 @@ static inline int fscrypt_notsupp_inherit_context(struct inode *p, { return -EOPNOTSUPP; } + +/* keyinfo.c */ +static inline int fscrypt_notsupp_get_encryption_info(struct inode *i) +{ + return -EOPNOTSUPP; +} + +static inline void fscrypt_notsupp_put_encryption_info(struct inode *i, + struct fscrypt_info *f) +{ + return; +} #endif /* _LINUX_FSCRYPTO_H */ -- 2.6.3