From patchwork Thu Oct 13 06:39:58 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nikolaus Voss X-Patchwork-Id: 13005672 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 4DEBAC4332F for ; Thu, 13 Oct 2022 06:43:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229484AbiJMGnP (ORCPT ); Thu, 13 Oct 2022 02:43:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34000 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229459AbiJMGnO (ORCPT ); Thu, 13 Oct 2022 02:43:14 -0400 Received: from mail.steuer-voss.de (mail.steuer-voss.de [85.183.69.95]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AB49BDCAC4; Wed, 12 Oct 2022 23:43:12 -0700 (PDT) X-Virus-Scanned: Debian amavisd-new at mail.steuer-voss.de Received: by mail.steuer-voss.de (Postfix, from userid 1000) id 857011E25; Thu, 13 Oct 2022 08:43:08 +0200 (CEST) From: Nikolaus Voss To: Mimi Zohar , David Howells , Jarkko Sakkinen , James Morris , "Serge E. Hallyn" , Yael Tzur , Cyril Hrubis , Petr Vorel Cc: linux-integrity@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Date: Thu, 13 Oct 2022 08:39:58 +0200 Subject: [PATCH v4] KEYS: encrypted: fix key instantiation with user-provided data Message-Id: <20221013064308.857011E25@mail.steuer-voss.de> Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org Commit cd3bc044af48 ("KEYS: encrypted: Instantiate key with user-provided decrypted data") added key instantiation with user provided decrypted data. The user data is hex-ascii-encoded but was just memcpy'ed to the binary buffer. Fix this to use hex2bin instead. Old keys created from user provided decrypted data saved with "keyctl pipe" are still valid, however if the key is recreated from decrypted data the old key must be converted to the correct format. This can be done with a small shell script, e.g.: BROKENKEY=abcdefABCDEF1234567890aaaaaaaaaa NEWKEY=$(echo -ne $BROKENKEY | xxd -p -c32) keyctl add user masterkey "$(cat masterkey.bin)" @u keyctl add encrypted testkey "new user:masterkey 32 $NEWKEY" @u It is encouraged to switch to a new key because the effective key size of the old keys is only half of the specified size. The corresponding test for the Linux Test Project ltp has also been fixed (see link below). Fixes: cd3bc044af48 ("KEYS: encrypted: Instantiate key with user-provided decrypted data") Cc: stable Link: https://lore.kernel.org/ltp/20221006081709.92303897@mail.steuer-voss.de/ Signed-off-by: Nikolaus Voss Reviewed-by: Mimi Zohar Reviewed-by: Jarkko Sakkinen --- Changes ======= v4: - fixed link v3: - use generated random key in example, reformat commit message v2: - clarify commit message, add example to recover old/broken keys - improve example in Documentation/security/keys/trusted-encrypted.rst - add link to ltp patch Documentation/security/keys/trusted-encrypted.rst | 3 ++- security/keys/encrypted-keys/encrypted.c | 6 +++--- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Documentation/security/keys/trusted-encrypted.rst index 0bfb4c339748..9bc9db8ec651 100644 --- a/Documentation/security/keys/trusted-encrypted.rst +++ b/Documentation/security/keys/trusted-encrypted.rst @@ -350,7 +350,8 @@ Load an encrypted key "evm" from saved blob:: Instantiate an encrypted key "evm" using user-provided decrypted data:: - $ keyctl add encrypted evm "new default user:kmk 32 `cat evm_decrypted_data.blob`" @u + $ evmkey=$(dd if=/dev/urandom bs=1 count=32 | xxd -c32 -p) + $ keyctl add encrypted evm "new default user:kmk 32 $evmkey" @u 794890253 $ keyctl print 794890253 diff --git a/security/keys/encrypted-keys/encrypted.c b/security/keys/encrypted-keys/encrypted.c index e05cfc2e49ae..1e313982af02 100644 --- a/security/keys/encrypted-keys/encrypted.c +++ b/security/keys/encrypted-keys/encrypted.c @@ -627,7 +627,7 @@ static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, pr_err("encrypted key: instantiation of keys using provided decrypted data is disabled since CONFIG_USER_DECRYPTED_DATA is set to false\n"); return ERR_PTR(-EINVAL); } - if (strlen(decrypted_data) != decrypted_datalen) { + if (strlen(decrypted_data) != decrypted_datalen * 2) { pr_err("encrypted key: decrypted data provided does not match decrypted data length provided\n"); return ERR_PTR(-EINVAL); } @@ -791,8 +791,8 @@ static int encrypted_init(struct encrypted_key_payload *epayload, ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv); } else if (decrypted_data) { get_random_bytes(epayload->iv, ivsize); - memcpy(epayload->decrypted_data, decrypted_data, - epayload->decrypted_datalen); + ret = hex2bin(epayload->decrypted_data, decrypted_data, + epayload->decrypted_datalen); } else { get_random_bytes(epayload->iv, ivsize); get_random_bytes(epayload->decrypted_data, epayload->decrypted_datalen);