From patchwork Tue Apr 18 17:04:40 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sweet Tea Dorminy X-Patchwork-Id: 13215958 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 370C7C77B78 for ; Tue, 18 Apr 2023 17:05:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231379AbjDRRFX (ORCPT ); Tue, 18 Apr 2023 13:05:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48678 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230526AbjDRRFW (ORCPT ); Tue, 18 Apr 2023 13:05:22 -0400 Received: from box.fidei.email (box.fidei.email [71.19.144.250]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A985BAF06 for ; Tue, 18 Apr 2023 10:05:14 -0700 (PDT) Received: from authenticated-user (box.fidei.email [71.19.144.250]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by box.fidei.email (Postfix) with ESMTPSA id E2C3B80261; Tue, 18 Apr 2023 13:05:13 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=dorminy.me; s=mail; t=1681837514; bh=dEb4cofQP0SC/9D0jU/fr3XiGsvihKGFpokT9e+n0h0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YXJp/BUa5tFaZ9bm6jFMUlZdYVyd0OEw5yCHlz2FsHyH3rnumV436sQR1NiNel9eE bZz8vRekdkw8O9P5ahL7DSk/VvnxhJlgmHbVH3+WCWtlYgLpL/zSvvAsAo7SV4mExp +KW943tetKn8Qg38DgkKJRP3jxtMXP34oIZG8vKRLMVxFduR0QVSMslZSpc4YDl1MH XtYCGMB/5NAuBenhG1SulFZK422ZkjhuZMWLVFnWZ/dlmplPXwDE5/86lN7NDnc0x8 6oQWluti89jqoQYbfGqVRLTlWHYU+fL5/cCBeSEOokXl9mnTL6ohm8Dm1wH63liOHW B49xImU9ufslg== From: Sweet Tea Dorminy To: Eric Biggers , "Theodore Y. Ts'o" , Jaegeuk Kim , linux-fscrypt@vger.kernel.org, kernel-team@meta.com Cc: Sweet Tea Dorminy Subject: [PATCH v3 03/11] fscrypt: split setup_per_mode_enc_key() Date: Tue, 18 Apr 2023 13:04:40 -0400 Message-Id: <26d53ea3abac1fddc7fee5e36fe512cd41d039fe.1681837335.git.sweettea-kernel@dorminy.me> In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org At present, setup_per_mode_enc_key() tries to find, within an array of mode keys in the master key, an already prepared key, and if it doesn't find a pre-prepared key, sets up a new one. This caching is not super clear, at least to me, and splitting this function makes it clearer. Signed-off-by: Sweet Tea Dorminy --- fs/crypto/keysetup.c | 59 +++++++++++++++++++++++++++----------------- 1 file changed, 36 insertions(+), 23 deletions(-) diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c index 727d473b6b03..69bd27b7e9d8 100644 --- a/fs/crypto/keysetup.c +++ b/fs/crypto/keysetup.c @@ -184,34 +184,24 @@ int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key) return fscrypt_prepare_key(&ci->ci_enc_key, raw_key, ci); } -static int setup_per_mode_enc_key(struct fscrypt_info *ci, - struct fscrypt_master_key *mk, - struct fscrypt_prepared_key *keys, - u8 hkdf_context, bool include_fs_uuid) +static int setup_new_mode_prepared_key(struct fscrypt_master_key *mk, + struct fscrypt_prepared_key *prep_key, + const struct fscrypt_info *ci, + u8 hkdf_context, bool include_fs_uuid) { const struct inode *inode = ci->ci_inode; const struct super_block *sb = inode->i_sb; struct fscrypt_mode *mode = ci->ci_mode; const u8 mode_num = mode - fscrypt_modes; - struct fscrypt_prepared_key *prep_key; u8 mode_key[FSCRYPT_MAX_KEY_SIZE]; u8 hkdf_info[sizeof(mode_num) + sizeof(sb->s_uuid)]; unsigned int hkdf_infolen = 0; int err; - if (WARN_ON_ONCE(mode_num > FSCRYPT_MODE_MAX)) - return -EINVAL; - - prep_key = &keys[mode_num]; - if (fscrypt_is_key_prepared(prep_key, ci)) { - ci->ci_enc_key = *prep_key; - return 0; - } - mutex_lock(&fscrypt_mode_key_setup_mutex); if (fscrypt_is_key_prepared(prep_key, ci)) - goto done_unlock; + goto out_unlock; BUILD_BUG_ON(sizeof(mode_num) != 1); BUILD_BUG_ON(sizeof(sb->s_uuid) != 16); @@ -229,16 +219,39 @@ static int setup_per_mode_enc_key(struct fscrypt_info *ci, goto out_unlock; err = fscrypt_prepare_key(prep_key, mode_key, ci); memzero_explicit(mode_key, mode->keysize); - if (err) - goto out_unlock; -done_unlock: - ci->ci_enc_key = *prep_key; - err = 0; + out_unlock: mutex_unlock(&fscrypt_mode_key_setup_mutex); return err; } +static int find_mode_prepared_key(struct fscrypt_info *ci, + struct fscrypt_master_key *mk, + struct fscrypt_prepared_key *keys, + u8 hkdf_context, bool include_fs_uuid) +{ + struct fscrypt_mode *mode = ci->ci_mode; + const u8 mode_num = mode - fscrypt_modes; + struct fscrypt_prepared_key *prep_key; + int err; + + if (WARN_ON_ONCE(mode_num > FSCRYPT_MODE_MAX)) + return -EINVAL; + + prep_key = &keys[mode_num]; + if (fscrypt_is_key_prepared(prep_key, ci)) { + ci->ci_enc_key = *prep_key; + return 0; + } + err = setup_new_mode_prepared_key(mk, prep_key, ci, hkdf_context, + include_fs_uuid); + if (err) + return err; + + ci->ci_enc_key = *prep_key; + return 0; +} + /* * Derive a SipHash key from the given fscrypt master key and the given * application-specific information string. @@ -294,7 +307,7 @@ static int fscrypt_setup_iv_ino_lblk_32_key(struct fscrypt_info *ci, { int err; - err = setup_per_mode_enc_key(ci, mk, mk->mk_iv_ino_lblk_32_keys, + err = find_mode_prepared_key(ci, mk, mk->mk_iv_ino_lblk_32_keys, HKDF_CONTEXT_IV_INO_LBLK_32_KEY, true); if (err) return err; @@ -344,7 +357,7 @@ static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci, * encryption key. This ensures that the master key is * consistently used only for HKDF, avoiding key reuse issues. */ - err = setup_per_mode_enc_key(ci, mk, mk->mk_direct_keys, + err = find_mode_prepared_key(ci, mk, mk->mk_direct_keys, HKDF_CONTEXT_DIRECT_KEY, false); } else if (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) { @@ -354,7 +367,7 @@ static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci, * the IVs. This format is optimized for use with inline * encryption hardware compliant with the UFS standard. */ - err = setup_per_mode_enc_key(ci, mk, mk->mk_iv_ino_lblk_64_keys, + err = find_mode_prepared_key(ci, mk, mk->mk_iv_ino_lblk_64_keys, HKDF_CONTEXT_IV_INO_LBLK_64_KEY, true); } else if (ci->ci_policy.v2.flags &