From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Mon, 11 Sep 2023 18:00:47 +0200 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1qfjLE-00BfSQ-6J for lore@lore.pengutronix.de; Mon, 11 Sep 2023 18:00:47 +0200 Received: from bombadil.infradead.org ([2607:7c80:54:3::133]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1qfjLC-0004MH-8t for lore@pengutronix.de; Mon, 11 Sep 2023 18:00:46 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-Type: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=7uuIGaJAQGynjy8cqrsitmX2ATtcsPgpVhzZBf1yuXE=; b=fuqEi5mncnWtahdULd6x7vkMKs rI/AvqnCvWxs7DG2P8JeBNF56yd6+xgzx5TPNgI+5mo2WHcP8YluAjUVm6kgA6mMRCF0AfL6vhX+O JhB1XyQ9WIeqjsCrv0DihRCOenFwB96HiktEV8wIQJLu1F27FNBhF3UcYiul41uLIHjSbux8wsHTl UD6q1juuYGAhNjlmgqU82f3hBHTZSjD2hQRxQtCbtyNccTv+zVmc6hKRkcGBbSiAMvmQfkj1C913l CZn2/nVSpSrND+G/ylN9s8GXfB1LHoztDN0qQ1PCIXBN4Uw032YQYdCK+qxAmWJ398+Fr6IEb4HKz ALkgCUGA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qfjK5-000xKC-1j; Mon, 11 Sep 2023 15:59:37 +0000 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qfjK1-000xIX-1w for barebox@lists.infradead.org; Mon, 11 Sep 2023 15:59:35 +0000 Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1qfjK0-0003z8-A5; Mon, 11 Sep 2023 17:59:32 +0200 Received: from [2a0a:edc0:0:1101:1d::54] (helo=dude05.red.stw.pengutronix.de) by drehscheibe.grey.stw.pengutronix.de with esmtp (Exim 4.94.2) (envelope-from ) id 1qfjJz-005aH8-Ty; Mon, 11 Sep 2023 17:59:31 +0200 Received: from afa by dude05.red.stw.pengutronix.de with local (Exim 4.96) (envelope-from ) id 1qfjJy-00Ft0P-2e; Mon, 11 Sep 2023 17:59:30 +0200 From: Ahmad Fatoum To: barebox@lists.infradead.org Cc: Alexander Shiyan , Ahmad Fatoum Date: Mon, 11 Sep 2023 17:59:25 +0200 Message-Id: <20230911155927.3786335-1-a.fatoum@pengutronix.de> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230911_085933_641619_644FBEC3 X-CRM114-Status: GOOD ( 19.83 ) X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:3::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.whiteo.stw.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-4.9 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: [PATCH 1/3] common: machine_id: support deriving app specific UUIDs X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.whiteo.stw.pengutronix.de) libsystemd provides a sd_id128_get_machine_app_specific() function that allows deriving an application specific UUID without directly leaking the machine ID. Let's provide an equivalent for barebox that will be used in a following commit to generate a stable MAC instead of randomizing it. Signed-off-by: Ahmad Fatoum --- common/machine_id.c | 84 ++++++++++++++++++++++++++++++++++++++++++-- include/linux/uuid.h | 8 +++++ include/machine_id.h | 10 ++++++ 3 files changed, 100 insertions(+), 2 deletions(-) diff --git a/common/machine_id.c b/common/machine_id.c index 8c273b934989..edc8ad0ac156 100644 --- a/common/machine_id.c +++ b/common/machine_id.c @@ -13,17 +13,96 @@ #define MACHINE_ID_LENGTH 32 +static bool __machine_id_initialized; static void *__machine_id_hashable; static size_t __machine_id_hashable_length; - +/** + * machine_id_set_hashable - Provide per-board unique data + * @hashable: Buffer + * @len: size of buffer + * + * The data supplied to the last call of this function prior to + * late_initcall will be hashed and stored into global.machine_id, + * which can be later used for fixup into the kernel command line + * or for deriving application specific unique IDs via + * machine_id_get_app_specific(). + */ void machine_id_set_hashable(const void *hashable, size_t len) { - __machine_id_hashable = xmemdup(hashable, len); __machine_id_hashable_length = len; } +/** + * machine_id_get_app_specific - Generates an application-specific UUID + * @result: UUID output of the function + * @...: pairs of (const void *, size_t) arguments of data to factor + * into the UUID followed by a NULL sentinel value. + * + * Combines the machine ID with the application specific varargs data + * to arrive at an application-specific and board-specific UUID that is + * stable and unique. + * + * The function returns 0 if a UUID was successfully written into @result + * and a negative error code otherwise. + */ +int machine_id_get_app_specific(uuid_t *result, ...) +{ + static u8 hmac[SHA256_DIGEST_SIZE]; + const void *data; + size_t size; + va_list args; + struct digest *d; + int ret; + + if (!__machine_id_initialized) + return -ENODATA; + + d = digest_alloc("hmac(sha256)"); + if (!d) + return -ENOSYS; + + ret = digest_set_key(d, __machine_id_hashable, __machine_id_hashable_length); + if (ret) + goto out; + + ret = digest_init(d); + if (ret) + goto out; + + ret = -ENODATA; + + va_start(args, result); + + while ((data = va_arg(args, const void *))) { + size = va_arg(args, size_t); + + ret = digest_update(d, data, size); + if (ret) + break; + } + + va_end(args); + + if (ret) + goto out; + + ret = digest_final(d, hmac); + if (ret) + goto out; + + /* Take only the first half. */ + memcpy(result, hmac, min(sizeof(hmac), sizeof(*result))); + + uuid_make_v4(result); + +out: + digest_free(d); + + return ret; +} + static int machine_id_set_globalvar(void) { struct digest *digest = NULL; @@ -61,6 +140,7 @@ static int machine_id_set_globalvar(void) env_machine_id = basprintf("%.*s", MACHINE_ID_LENGTH, hex_machine_id); globalvar_add_simple("machine_id", env_machine_id); free(env_machine_id); + __machine_id_initialized = true; out: digest_free(digest); diff --git a/include/linux/uuid.h b/include/linux/uuid.h index 6b1a3efa1e0b..1e4ffb343452 100644 --- a/include/linux/uuid.h +++ b/include/linux/uuid.h @@ -107,6 +107,14 @@ extern const u8 uuid_index[16]; int guid_parse(const char *uuid, guid_t *u); int uuid_parse(const char *uuid, uuid_t *u); +static inline void uuid_make_v4(uuid_t *u) { + /* Set UUID version to 4 --- truly random generation */ + u->b[6] = (u->b[6] & 0x0F) | 0x40; + + /* Set the UUID variant to DCE */ + u->b[8] = (u->b[8] & 0x3F) | 0x80; +} + /* MEI UUID type, don't use anywhere else */ #include diff --git a/include/machine_id.h b/include/machine_id.h index e30bbada1acd..0ed4052ec47c 100644 --- a/include/machine_id.h +++ b/include/machine_id.h @@ -3,9 +3,13 @@ #ifndef __MACHINE_ID_H__ #define __MACHINE_ID_H__ +#include +#include + #if IS_ENABLED(CONFIG_MACHINE_ID) void machine_id_set_hashable(const void *hashable, size_t len); +int machine_id_get_app_specific(uuid_t *result, ...) __attribute__((__sentinel__)); #else @@ -13,6 +17,12 @@ static inline void machine_id_set_hashable(const void *hashable, size_t len) { } +static inline int machine_id_get_app_specific(uuid_t *result, ...) + __attribute__((__sentinel__)); +{ + return -ENOSYS; +} + #endif /* CONFIG_MACHINE_ID */ #endif /* __MACHINE_ID_H__ */ -- 2.39.2