From patchwork Wed Nov 16 16:16:40 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: 625287 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 46DB7C4332F for ; Wed, 16 Nov 2022 16:17:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231221AbiKPQRU (ORCPT ); Wed, 16 Nov 2022 11:17:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54214 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237798AbiKPQRM (ORCPT ); Wed, 16 Nov 2022 11:17:12 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 188F556ED6; Wed, 16 Nov 2022 08:17:12 -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 dfw.source.kernel.org (Postfix) with ESMTPS id AC68161EA1; Wed, 16 Nov 2022 16:17:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 71899C433D6; Wed, 16 Nov 2022 16:17:10 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="LMtT5g0j" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1668615429; 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=CtDPiLK4h3/qHxrwQ4LOLbCxpSziESOZ1KCyGGtwumM=; b=LMtT5g0jbC2n+YnsJpCMOismh75conFLfg9ZfXbF3B4K+4Cdpx+P3xEycUSpeDoIb3L1+f PaDeZDIuBn2qmyEaYUzK/TP6VWZuLGyCGF46Q8ZJABCXgPm0ZeLbYiPAceevFmxQGaICQP 80fKEVsVLBK/swJSk1z8LnuUnUIGcw0= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 99e58ae7 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Wed, 16 Nov 2022 16:17:09 +0000 (UTC) From: "Jason A. Donenfeld" To: linux-efi@vger.kernel.org, linux-crypto@vger.kernel.org Cc: "Jason A. Donenfeld" , Ard Biesheuvel , Lennart Poettering Subject: [PATCH RFC v1 4/6] efi: stub: use random seed from EFI variable Date: Wed, 16 Nov 2022 17:16:40 +0100 Message-Id: <20221116161642.1670235-5-Jason@zx2c4.com> In-Reply-To: <20221116161642.1670235-1-Jason@zx2c4.com> References: <20221116161642.1670235-1-Jason@zx2c4.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org Since we have some storage, we can manage non-volatile seeds directly from EFISTUB. This commit passes the contents of an EFI variable to the kernel via the existing configuration table. Signed-off-by: Jason A. Donenfeld --- drivers/firmware/efi/libstub/random.c | 59 +++++++++++++++++++++------ include/linux/efi.h | 1 + 2 files changed, 48 insertions(+), 12 deletions(-) diff --git a/drivers/firmware/efi/libstub/random.c b/drivers/firmware/efi/libstub/random.c index f85d2c066877..1e72013a6457 100644 --- a/drivers/firmware/efi/libstub/random.c +++ b/drivers/firmware/efi/libstub/random.c @@ -67,14 +67,25 @@ efi_status_t efi_random_get_seed(void) efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID; efi_guid_t rng_algo_raw = EFI_RNG_ALGORITHM_RAW; efi_guid_t rng_table_guid = LINUX_EFI_RANDOM_SEED_TABLE_GUID; + efi_char16_t rng_nv_seed_var[] = LINUX_EFI_RANDOM_NV_SEED_VAR; 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(rng_nv_seed_var, &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 +94,7 @@ 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 +114,7 @@ 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 +122,40 @@ 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); + /* + * Zero it out before committing to using it. TODO: in the + * future, maybe we can hash it forward instead, which is + * better and also reduces the amount of writes here. + */ + status = set_efi_var(rng_nv_seed_var, &rng_table_guid, + EFI_VARIABLE_NON_VOLATILE | + EFI_VARIABLE_BOOTSERVICE_ACCESS | + EFI_VARIABLE_RUNTIME_ACCESS, nv_seed_size, nv_seed); + if (status == EFI_SUCCESS) + status = set_efi_var(rng_nv_seed_var, &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 +170,7 @@ 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"); diff --git a/include/linux/efi.h b/include/linux/efi.h index 4aa1dbc7b064..0e93510b23b5 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -408,6 +408,7 @@ void efi_native_runtime_setup(void); #define LINUX_EFI_ARM_CPU_STATE_TABLE_GUID EFI_GUID(0xef79e4aa, 0x3c3d, 0x4989, 0xb9, 0x02, 0x07, 0xa9, 0x43, 0xe5, 0x50, 0xd2) #define LINUX_EFI_LOADER_ENTRY_GUID EFI_GUID(0x4a67b082, 0x0a4c, 0x41cf, 0xb6, 0xc7, 0x44, 0x0b, 0x29, 0xbb, 0x8c, 0x4f) #define LINUX_EFI_RANDOM_SEED_TABLE_GUID EFI_GUID(0x1ce1e5bc, 0x7ceb, 0x42f2, 0x81, 0xe5, 0x8a, 0xad, 0xf1, 0x80, 0xf5, 0x7b) +#define LINUX_EFI_RANDOM_NV_SEED_VAR L"RandomNVSeed" #define LINUX_EFI_TPM_EVENT_LOG_GUID EFI_GUID(0xb7799cb0, 0xeca2, 0x4943, 0x96, 0x67, 0x1f, 0xae, 0x07, 0xb7, 0x47, 0xfa) #define LINUX_EFI_TPM_FINAL_LOG_GUID EFI_GUID(0x1e2ed096, 0x30e2, 0x4254, 0xbd, 0x89, 0x86, 0x3b, 0xbe, 0xf8, 0x23, 0x25) #define LINUX_EFI_MEMRESERVE_TABLE_GUID EFI_GUID(0x888eb0c6, 0x8ede, 0x4ff5, 0xa8, 0xf0, 0x9a, 0xee, 0x5c, 0xb9, 0x77, 0xc2) From patchwork Wed Nov 16 16:16:41 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: 625285 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 5F480C43219 for ; Wed, 16 Nov 2022 16:17:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233740AbiKPQRX (ORCPT ); Wed, 16 Nov 2022 11:17:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54268 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238085AbiKPQRR (ORCPT ); Wed, 16 Nov 2022 11:17:17 -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 8514BD135; Wed, 16 Nov 2022 08:17:16 -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 42997B81DD9; Wed, 16 Nov 2022 16:17:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5CD32C433D6; Wed, 16 Nov 2022 16:17:13 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="DO7/xtKp" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1668615433; 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=SutN9URRaDRkoRI4sfbAAJPIQ0pLYtrJHZUE/tUAx5Q=; b=DO7/xtKpmJ+qbHUkvjOiJl95LOYlJrLNXrCH1BXJ5r/WuFITUd9HEjZ/RqdSLzoGooTmYc gfHssY9a8mQGQCUu90xJOpKx3QeILTHlt5an1KxtzQ2WBAcZ4bsfucAykgwEOaq44uGweW bOC9xpFA89pnO1UW3k8kh5xasxnPH/E= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 8e977426 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Wed, 16 Nov 2022 16:17:12 +0000 (UTC) From: "Jason A. Donenfeld" To: linux-efi@vger.kernel.org, linux-crypto@vger.kernel.org Cc: "Jason A. Donenfeld" , Ard Biesheuvel , Lennart Poettering Subject: [PATCH RFC v1 5/6] efi: efivarfs: prohibit reading random seed variables Date: Wed, 16 Nov 2022 17:16:41 +0100 Message-Id: <20221116161642.1670235-6-Jason@zx2c4.com> In-Reply-To: <20221116161642.1670235-1-Jason@zx2c4.com> References: <20221116161642.1670235-1-Jason@zx2c4.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org Variables in the random seed GUID must remain secret, so deny all reads to them. Signed-off-by: Jason A. Donenfeld --- fs/efivarfs/file.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/efivarfs/file.c b/fs/efivarfs/file.c index d57ee15874f9..08996ba3a373 100644 --- a/fs/efivarfs/file.c +++ b/fs/efivarfs/file.c @@ -76,6 +76,9 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf, while (!__ratelimit(&file->f_cred->user->ratelimit)) msleep(50); + if (guid_equal(&var->var.VendorGuid, &LINUX_EFI_RANDOM_SEED_TABLE_GUID)) + return -EPERM; + err = efivar_entry_size(var, &datasize); /* From patchwork Wed Nov 16 16:16:42 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: 625284 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 A531BC4332F for ; Wed, 16 Nov 2022 16:17:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233463AbiKPQRY (ORCPT ); Wed, 16 Nov 2022 11:17:24 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54324 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232506AbiKPQRT (ORCPT ); Wed, 16 Nov 2022 11:17:19 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C6C1257B4A; Wed, 16 Nov 2022 08:17:18 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 5D66761EA1; Wed, 16 Nov 2022 16:17:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 380C4C433C1; Wed, 16 Nov 2022 16:17:17 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="gP8ZSBvF" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1668615436; 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=T8rpk19kPkTtPMi5LUcmORLt2HUDUjWWv1DWoYLEx0I=; b=gP8ZSBvFYttV9FkdX6gi6A9SgRb4YQWPgyka74GC2aO+WXfMXjyb8bfOjzxLhH8q1nNS8p u0qnicPF58AhsnY8+ODg1ml+iE0X15khp7H6L4Ko6TuBx1+bDiXW8urDyukGhGAK+Bdc/a Y6w76zi4j/dcPbLRZd8EnDy3EyjWw9Q= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 2e2b34f2 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Wed, 16 Nov 2022 16:17:15 +0000 (UTC) From: "Jason A. Donenfeld" To: linux-efi@vger.kernel.org, linux-crypto@vger.kernel.org Cc: "Jason A. Donenfeld" , Ard Biesheuvel , Lennart Poettering Subject: [PATCH RFC v1 6/6] efi: refresh non-volatile random seed when RNG is initialized Date: Wed, 16 Nov 2022 17:16:42 +0100 Message-Id: <20221116161642.1670235-7-Jason@zx2c4.com> In-Reply-To: <20221116161642.1670235-1-Jason@zx2c4.com> References: <20221116161642.1670235-1-Jason@zx2c4.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org Register a notifier so that when the RNG is initialized, the EFI variable containing the random seed can be refreshed. Signed-off-by: Jason A. Donenfeld --- drivers/firmware/efi/efi.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index a46df5d1d094..db247a52d3c2 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -337,6 +337,19 @@ static void __init efi_debugfs_init(void) static inline void efi_debugfs_init(void) {} #endif +static int refresh_nv_rng_seed(struct notifier_block *nb, unsigned long action, void *data) +{ + u8 seed[EFI_RANDOM_SEED_SIZE]; + + get_random_bytes(seed, sizeof(seed)); + efi.set_variable(LINUX_EFI_RANDOM_NV_SEED_VAR, &LINUX_EFI_RANDOM_SEED_TABLE_GUID, + EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | + EFI_VARIABLE_RUNTIME_ACCESS, sizeof(seed), seed); + memzero_explicit(seed, sizeof(seed)); + return 0; +} +static struct notifier_block refresh_nv_rng_seed_nb = { .notifier_call = refresh_nv_rng_seed }; + /* * We register the efi subsystem with the firmware subsystem and the * efivars subsystem with the efi subsystem, if the system was booted with @@ -413,6 +426,7 @@ static int __init efisubsys_init(void) platform_device_register_simple("efi_secret", 0, NULL, 0); #endif + notify_on_rng_initialized(&refresh_nv_rng_seed_nb); return 0; err_remove_group: