From patchwork Tue Nov 22 02:04:01 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Jason A. Donenfeld" X-Patchwork-Id: 627802 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 CAF01C4332F for ; Tue, 22 Nov 2022 02:04:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232482AbiKVCEd (ORCPT ); Mon, 21 Nov 2022 21:04:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232464AbiKVCEV (ORCPT ); Mon, 21 Nov 2022 21:04:21 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9F3EBDEAE8; Mon, 21 Nov 2022 18:04:20 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 4FE38B8136A; Tue, 22 Nov 2022 02:04:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 54890C433D6; Tue, 22 Nov 2022 02:04:17 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="dl6cffAN" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1669082656; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=sRRUJbIcSnr8ZTNHq3sI4HzNBqRBBqfcvWMclFygaoU=; b=dl6cffANAexQpw8uQfoTRvNYbcmSWvDo6qlGlaZVWbcJMW4joFsgo1HkW3BKX/Z9uQfEF+ sm+cpTuhIfgQtAiv5zJUtt+kTMoFMCkqQ89tknm0VUsPDvtUDWzW/BEwer/jfbbE1UP8Tn lp+6jTFLssgWXDdQA9BBGar4O4XzPmA= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 57080fb0 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Tue, 22 Nov 2022 02:04:16 +0000 (UTC) From: "Jason A. Donenfeld" To: linux-efi@vger.kernel.org, linux-crypto@vger.kernel.org, patches@lists.linux.dev, linux-kernel@vger.kernel.org, ardb@kernel.org Cc: "Jason A. Donenfeld" Subject: [PATCH v3 2/5] efi: stub: use random seed from EFI variable Date: Tue, 22 Nov 2022 03:04:01 +0100 Message-Id: <20221122020404.3476063-3-Jason@zx2c4.com> In-Reply-To: <20221122020404.3476063-1-Jason@zx2c4.com> References: <20221122020404.3476063-1-Jason@zx2c4.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org EFI has a rather unique benefit that it has access to some limited non-volatile storage, where the kernel can store a random seed. Read that seed in EFISTUB and concatenate it with other seeds we wind up passing onward to the kernel in the configuration table. This is complementary to the current other two sources - previous bootloaders, and the EFI RNG protocol. Signed-off-by: Jason A. Donenfeld --- drivers/firmware/efi/libstub/random.c | 55 +++++++++++++++++++++------ 1 file changed, 43 insertions(+), 12 deletions(-) diff --git a/drivers/firmware/efi/libstub/random.c b/drivers/firmware/efi/libstub/random.c index f85d2c066877..64aa6e7f3a17 100644 --- a/drivers/firmware/efi/libstub/random.c +++ b/drivers/firmware/efi/libstub/random.c @@ -68,13 +68,23 @@ efi_status_t efi_random_get_seed(void) efi_guid_t rng_algo_raw = EFI_RNG_ALGORITHM_RAW; efi_guid_t rng_table_guid = LINUX_EFI_RANDOM_SEED_TABLE_GUID; struct linux_efi_random_seed *prev_seed, *seed = NULL; - int prev_seed_size = 0, seed_size = EFI_RANDOM_SEED_SIZE; + u8 nv_seed[EFI_RANDOM_SEED_SIZE]; + unsigned long prev_seed_size = 0, nv_seed_size = sizeof(nv_seed), seed_size = 0, offset = 0; efi_rng_protocol_t *rng = NULL; efi_status_t status; status = efi_bs_call(locate_protocol, &rng_proto, NULL, (void **)&rng); - if (status != EFI_SUCCESS) - return status; + if (status == EFI_SUCCESS) + seed_size += EFI_RANDOM_SEED_SIZE; + + status = get_efi_var(L"RandomSeed", &rng_table_guid, NULL, &nv_seed_size, nv_seed); + if (status == EFI_SUCCESS) + seed_size += nv_seed_size; + else + nv_seed_size = 0; + + if (!seed_size) + return EFI_NOT_FOUND; /* * Check whether a seed was provided by a prior boot stage. In that @@ -83,7 +93,7 @@ efi_status_t efi_random_get_seed(void) * Note that we should read the seed size with caution, in case the * table got corrupted in memory somehow. */ - prev_seed = get_efi_config_table(LINUX_EFI_RANDOM_SEED_TABLE_GUID); + prev_seed = get_efi_config_table(rng_table_guid); if (prev_seed && prev_seed->size <= 512U) { prev_seed_size = prev_seed->size; seed_size += prev_seed_size; @@ -103,7 +113,7 @@ efi_status_t efi_random_get_seed(void) } status = efi_call_proto(rng, get_rng, &rng_algo_raw, - EFI_RANDOM_SEED_SIZE, seed->bits); + EFI_RANDOM_SEED_SIZE, seed->bits + offset); if (status == EFI_UNSUPPORTED) /* @@ -111,16 +121,37 @@ efi_status_t efi_random_get_seed(void) * is not implemented. */ status = efi_call_proto(rng, get_rng, NULL, - EFI_RANDOM_SEED_SIZE, seed->bits); + EFI_RANDOM_SEED_SIZE, seed->bits + offset); - if (status != EFI_SUCCESS) + if (status == EFI_SUCCESS) + offset += EFI_RANDOM_SEED_SIZE; + + if (nv_seed_size) { + memcpy(seed->bits + offset, nv_seed, nv_seed_size); + memzero_explicit(nv_seed, nv_seed_size); + /* + * We delete the seed here, and /hope/ that this causes EFI to + * also zero out its representation on disk. This is somewhat + * idealistic, but overwriting the variable with zeros is + * likely just as fraught too. TODO: in the future, maybe we + * can hash it forward instead, and write a new seed. + */ + status = set_efi_var(L"RandomSeed", &rng_table_guid, 0, 0, NULL); + if (status == EFI_SUCCESS) + offset += nv_seed_size; + else + memzero_explicit(seed->bits + offset, nv_seed_size); + } + + if (!offset) goto err_freepool; - seed->size = seed_size; - if (prev_seed_size) - memcpy(seed->bits + EFI_RANDOM_SEED_SIZE, prev_seed->bits, - prev_seed_size); + if (prev_seed_size) { + memcpy(seed->bits + offset, prev_seed->bits, prev_seed_size); + offset += prev_seed_size; + } + seed->size = offset; status = efi_bs_call(install_configuration_table, &rng_table_guid, seed); if (status != EFI_SUCCESS) goto err_freepool; @@ -135,7 +166,7 @@ efi_status_t efi_random_get_seed(void) err_freepool: memzero_explicit(seed, struct_size(seed, bits, seed_size)); efi_bs_call(free_pool, seed); - efi_warn("Failed to obtain seed from EFI_RNG_PROTOCOL\n"); + efi_warn("Failed to obtain seed from EFI_RNG_PROTOCOL and EFI variable\n"); err_warn: if (prev_seed) efi_warn("Retaining bootloader-supplied seed only"); From patchwork Tue Nov 22 02:04:03 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Jason A. Donenfeld" X-Patchwork-Id: 627801 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 68897C4321E for ; Tue, 22 Nov 2022 02:04:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232506AbiKVCEl (ORCPT ); Mon, 21 Nov 2022 21:04:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33660 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232459AbiKVCEc (ORCPT ); Mon, 21 Nov 2022 21:04:32 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5F26DE14D7; Mon, 21 Nov 2022 18:04:25 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 2403BB818E7; Tue, 22 Nov 2022 02:04:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4042BC433B5; Tue, 22 Nov 2022 02:04:22 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="Dp148rop" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1669082661; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=CQp5Xt1b1pHaswbZ86gvO2c+Ls0o4Gj7yCvAYqghZs4=; b=Dp148ropguWfBS6U4rGunOxWu3O9SFddDB/Y0n7mciWLwD8rlXvuG2ujfQZvGZvlIqvs/e sqP6W2u3zp8d3lf/WsFe95jZ34Fyue6k6vMbgXrgaRdcAAguucHbIVpgRD3pu6f835hTtB wc/KbEFVHfZLX3ytWRL6oT1/oPa1qFM= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 8231b6b4 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Tue, 22 Nov 2022 02:04:21 +0000 (UTC) From: "Jason A. Donenfeld" To: linux-efi@vger.kernel.org, linux-crypto@vger.kernel.org, patches@lists.linux.dev, linux-kernel@vger.kernel.org, ardb@kernel.org Cc: "Jason A. Donenfeld" , Petr Mladek Subject: [PATCH v3 4/5] vsprintf: initialize siphash key using notifier Date: Tue, 22 Nov 2022 03:04:03 +0100 Message-Id: <20221122020404.3476063-5-Jason@zx2c4.com> In-Reply-To: <20221122020404.3476063-1-Jason@zx2c4.com> References: <20221122020404.3476063-1-Jason@zx2c4.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org Rather than polling every second, use the new notifier to do this at exactly the right moment. Reviewed-by: Petr Mladek Signed-off-by: Jason A. Donenfeld --- lib/vsprintf.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 24f37bab8bc1..2d11541ee561 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -41,6 +41,7 @@ #include #include #include +#include #ifdef CONFIG_BLOCK #include #endif @@ -752,26 +753,21 @@ early_param("debug_boot_weak_hash", debug_boot_weak_hash_enable); static bool filled_random_ptr_key __read_mostly; static siphash_key_t ptr_key __read_mostly; -static void fill_ptr_key_workfn(struct work_struct *work); -static DECLARE_DELAYED_WORK(fill_ptr_key_work, fill_ptr_key_workfn); -static void fill_ptr_key_workfn(struct work_struct *work) +static int fill_ptr_key(struct notifier_block *nb, unsigned long action, void *data) { - if (!rng_is_initialized()) { - queue_delayed_work(system_unbound_wq, &fill_ptr_key_work, HZ * 2); - return; - } - get_random_bytes(&ptr_key, sizeof(ptr_key)); /* Pairs with smp_rmb() before reading ptr_key. */ smp_wmb(); WRITE_ONCE(filled_random_ptr_key, true); + return NOTIFY_DONE; } static int __init vsprintf_init_hashval(void) { - fill_ptr_key_workfn(NULL); + static struct notifier_block fill_ptr_key_nb = { .notifier_call = fill_ptr_key }; + execute_with_initialized_rng(&fill_ptr_key_nb); return 0; } subsys_initcall(vsprintf_init_hashval)