From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Mon, 03 Nov 2025 12:41:44 +0100 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 4.96) (envelope-from ) id 1vFswS-00EqBn-2j for lore@lore.pengutronix.de; Mon, 03 Nov 2025 12:41:44 +0100 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 1vFswS-0006Xs-3o for lore@pengutronix.de; Mon, 03 Nov 2025 12:41:44 +0100 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:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=st6fEji/oP5C9CQ9RGOR1Ge2excUVfz5lKNDMr+v7x4=; b=vZLiORYPHkRd3ASA0r5pFs4owL m/VjOYtXhcjXbKWzYrLeGrmfSNx/KTWi+w81Th8V1UFIBfcbwLMMyXwI1E28TGo7mRDr/tU14JbAt xg6Mh/7TY32MUUfyJrRb0EQzn3zR2zZDuKOp6D2W4huUXjvP6jrNTq+TuAGnBs4r5bNXZYttEr80j YZ90hIX/Coc9kKHJMDdYQ6+FXB536QPsnCxj+Kh/715M3AOaWa75WUylUVhGZk3QavDZQvRq1Xfzo Sya+wZ/OLH0MBVh8IAHL40t84EnYpOYItN0yUw20AGJ1ycHF7iaqX6OdXVQWtRXtHm7a4XxyUMKLi JB9/sH4w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vFsvv-00000009kig-2rpu; Mon, 03 Nov 2025 11:41:11 +0000 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vFsvs-00000009kiI-3ebB for barebox@lists.infradead.org; Mon, 03 Nov 2025 11:41:10 +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 1vFsvq-0006NO-V4; Mon, 03 Nov 2025 12:41:06 +0100 Received: from pty.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::c5]) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1vFsvq-006qsK-2W; Mon, 03 Nov 2025 12:41:06 +0100 Received: from sha by pty.whiteo.stw.pengutronix.de with local (Exim 4.96) (envelope-from ) id 1vFsvq-00GecP-2F; Mon, 03 Nov 2025 12:41:06 +0100 Date: Mon, 3 Nov 2025 12:41:06 +0100 From: Sascha Hauer To: Jonas Rebmann Cc: BAREBOX , Ahmad Fatoum Message-ID: References: <20251028-tlv-signature-v2-0-3bafce636ad7@pengutronix.de> <20251028-tlv-signature-v2-10-3bafce636ad7@pengutronix.de> <2249476f-03b5-404b-9a9b-feb69393ef1e@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2249476f-03b5-404b-9a9b-feb69393ef1e@pengutronix.de> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251103_034108_924687_871B447F X-CRM114-Status: GOOD ( 46.91 ) 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=-4.0 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: Re: [PATCH v2 10/17] common: tlv: Add TLV-Signature support 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, Nov 03, 2025 at 12:21:56PM +0100, Jonas Rebmann wrote: > Hi Sascha, > > On 2025-11-03 11:02, Sascha Hauer wrote: > > On Tue, Oct 28, 2025 at 07:03:15PM +0100, Jonas Rebmann wrote: > > > Implement TLV signature using the existing placeholders for it. Use the > > > existing cryptographic primitives and public key handling used for > > > fitimage verification. > > > > > > Signature is verified and then must be valid iff CONFIG_TLV_SIGNATURE is > > > enabled and a keyring is selected for the decoder. SHA256 hashing is > > > hardcoded for now. > > > > > > As 16 bit are well sufficient to store the length of the signature > > > section in bytes, reduce it to its least significant 16 bit and reserve > > > the remaining 16 bit for future use. > > > > > > As sig_len where the only reserved bits left, and where zero-reserved, > > > this leaves more wiggle room to still expand the format in the future. > > > > > > Signed-off-by: Jonas Rebmann > > > --- > > > common/Kconfig | 5 +++ > > > common/tlv/parser.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++++ > > > include/tlv/format.h | 22 ++++++++++--- > > > 3 files changed, 109 insertions(+), 5 deletions(-) > > > > > > diff --git a/common/Kconfig b/common/Kconfig > > > index d923d4c4b6..663465443d 100644 > > > --- a/common/Kconfig > > > +++ b/common/Kconfig > > > @@ -1122,6 +1122,11 @@ config TLV > > > barebox TLV is a scheme for storing factory data on non-volatile > > > storage. Unlike state, it's meant to be read-only. > > > +config TLV_SIGNATURE > > > + bool "barebox TLV signature support" > > > + depends on TLV > > > + select CRYPTO_BUILTIN_KEYS > > > + > > > config TLV_DRV > > > bool "barebox TLV generic driver" > > > depends on TLV > > > diff --git a/common/tlv/parser.c b/common/tlv/parser.c > > > index f74ada99d7..cbf45413dd 100644 > > > --- a/common/tlv/parser.c > > > +++ b/common/tlv/parser.c > > > @@ -1,6 +1,7 @@ > > > // SPDX-License-Identifier: GPL-2.0-only > > > #define pr_fmt(fmt) "barebox-tlv: " fmt > > > +#include "tlv/format.h" > > > #include > > > #include > > > @@ -9,6 +10,80 @@ > > > #include > > > #include > > > #include > > > +#include > > > + > > > +static int tlv_verify_try_key(const struct public_key *key, const uint8_t *sig, > > > + const uint32_t sig_len, const void *data, > > > + unsigned long data_len) > > > +{ > > > + enum hash_algo algo = HASH_ALGO_SHA256; > > > + int ret; > > > + struct digest *digest; > > > + void *hash; > > > + > > > + digest = digest_alloc_by_algo(algo); > > > + if (!digest) > > > + return -ENOMEM; > > > + > > > + digest_init(digest); > > > + if (IS_ERR(digest)) { > > > > What you meant to do here is > > > > ret = digest_init(digest); > > if (ret) { > > ... > > } > > > > I used IS_ERR() here simply because that's how I saw it in > common/image-fit.c. Will that need to be changed too then? I don't see that the return value of digest_init() is checked in common/image-fit.c. Yes, we should consistently check the return value of digest_init(). Anyway, my point was that your IS_ERR(digest) is bogus. > > > + for_each_public_key_keyring(key, id, keyring) { > > > + u32 spki_key = get_unaligned_le32(key->hash); > > > + > > > + if (spki_key == spki_tlv) { > > > + count_spki_matches++; > > > + ret = tlv_verify_try_key(key, spki_tlv_ptr + SPKI_LEN, sig_len - SPKI_LEN, header, payload_sz); > > > + if (!ret) > > > + return 0; > > > + pr_warn("TLV spki %08x matched available key but signature verification failed: %pe!\n", spki_tlv, ERR_PTR(ret)); > > > > Not sure what this warning is about. Either it can happen that there are > > two keys with the same hash in which case there's nothing to warn about, > > or it can't happen and you would return an error here. > > When this happens, there is either a 32-bit hash collision, or > something's broken, such as what we had last week, where ECDSA keys > where incorrectly initialized, leading to signature verification to > always fail even with a valid key. > > We can't error out here already because when we designed the TLV > signature verification feature we specified that in case of spki hash > collision, all matching keys must be tried. Ok, considering that a hash collision can happen we shouldn't warn about it. > > > + if (decoder->signature_keyring) { > > > + ret = tlv_verify(header, decoder->signature_keyring); > > > + if (ret) > > > + return ret; > > > > Does this mean I can bypass the verification just by putting some > > unsigned TLV data with TLV_MAGIC_BAREBOX_V1 into the TLV partition? > > If barebox_tlv_v1 or another unsigned decoder is enabled, its compatible > needs to be referenced in a devicetree node in order for unsigned TLVs > to be parseable (except when using the "TLV" command which does create a > new devicetree node named tlv). > > Even if both signed and unsigned decoder are both enabled and referenced > in the devicetree (and I can see applications where this may be > desirable), feeding the device with unsigned TLV data never lets you > modify the devicetree node that has a compatible string of a signed TLV > decoder. I see. I hoped I missed something :) Sascha -- 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 |