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Thu, 21 Sep 2023 13:12:37 +0200 Received: from [2a0a:edc0:2:b01:1d::c0] (helo=ptx.whiteo.stw.pengutronix.de) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1qjHbo-007uF1-Qx; Thu, 21 Sep 2023 13:12:36 +0200 Received: from sha by ptx.whiteo.stw.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1qjHbo-00AjRB-Ol; Thu, 21 Sep 2023 13:12:36 +0200 Date: Thu, 21 Sep 2023 13:12:36 +0200 To: Ahmad Fatoum Cc: barebox@lists.infradead.org, Alexander Shiyan Message-ID: <20230921111236.GD235829@pengutronix.de> References: <20230911155927.3786335-1-a.fatoum@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230911155927.3786335-1-a.fatoum@pengutronix.de> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-Accept-Language: de,en X-Accept-Content-Type: text/plain User-Agent: Mutt/1.10.1 (2018-07-13) From: Sascha Hauer X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230921_041239_114595_CAB0C803 X-CRM114-Status: GOOD ( 35.93 ) 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=-5.0 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: Re: [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) On Mon, Sep 11, 2023 at 05:59:25PM +0200, Ahmad Fatoum wrote: > 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(-) Applied 1/2 and 2/2, thanks Sascha > > 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 > > > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |