From mboxrd@z Thu Jan 1 00:00:00 1970 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 B8DA3C25B6B for ; Tue, 24 Oct 2023 03:53:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232640AbjJXDxk (ORCPT ); Mon, 23 Oct 2023 23:53:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54216 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232333AbjJXDwr (ORCPT ); Mon, 23 Oct 2023 23:52:47 -0400 Received: from mail-qv1-xf2e.google.com (mail-qv1-xf2e.google.com [IPv6:2607:f8b0:4864:20::f2e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 498A410F5 for ; Mon, 23 Oct 2023 20:52:33 -0700 (PDT) Received: by mail-qv1-xf2e.google.com with SMTP id 6a1803df08f44-66d264e67d8so23966996d6.1 for ; Mon, 23 Oct 2023 20:52:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=paul-moore.com; s=google; t=1698119552; x=1698724352; darn=vger.kernel.org; h=in-reply-to:references:subject:cc:to:from:message-id:date:from:to :cc:subject:date:message-id:reply-to; bh=hADcKA1UWPiRdnCHspcKD95SqFEOwQ8DvDpSU3O8eEs=; b=Y1TmY5hU2maUxcm+cCPoIANyQNDhz77DUHsDcpuV20CpkN/xDLtk7FVAPUKYx8yY/m KXRrupO0W9m3ph8n6iLiroZrtlyvIpPcxv+UfFORGgzXnrZZ0HbZhcXFExc9Ryx9EoJK ooDaxn7U/x/tSlzBc20F8nVd6F5IXUOSt760ZuP0JoHCEHAwTXcYgsOenNM8WC5/jjh1 osDuVRTpI1GNuCGppqRB56GUmTpqZY5TDVH7pXD0PayTlQWPyry5tKJLX36CNFUM7Uu8 mPijsr6GM2Dxl+tMojlMbCUNK7LA0q6zOf0IhbOSlL/DrNgu7a3+jjIvgqT/4fxacYvP PozQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698119552; x=1698724352; h=in-reply-to:references:subject:cc:to:from:message-id:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=hADcKA1UWPiRdnCHspcKD95SqFEOwQ8DvDpSU3O8eEs=; b=ZafiJBYZUByU9sy+WC2XEm4Sa4agCTCyuvLJVWwnWJFWLLSWvT/TtrzjZzX5kOms5T QXEHaTtQ+/fT33XoDN8t0iXGvpyqabUCXbRIGD93OaOl6xwhQkNoeZvP4Cty3Lyh2oOF WNsLof8UYdgyZekNEvCCFFLEKu4pisl8yn2/TydakZGYJ/lvWHZ34rBrL6IrkQG3icq0 XZ619Jd++9jm53SuxzLjmLsoWzbmv+pdI0p8/XwaeBG6au+sRYdl6ZzIbyFekS6PLbwj UZg94nAVyYpXwKrqbCH1SBAmgeRovSFnDDK6hke37Tbn59oqziIZ9xUSD3SF3HvijDf1 LDlg== X-Gm-Message-State: AOJu0YwCUumcOi5JDyfAV57wfsE3yMhfCum5LR08G93SLYq3csnx16QG HEHVwa3JdZButy7/ruM6zQtx X-Google-Smtp-Source: AGHT+IHQ4xi8G/il6wD4iHK2En8Uxy1HdELe4wcBegRDxlGyxxhycLWFO/wUSoQ+EGQvqRxRotIGzQ== X-Received: by 2002:ad4:5aa6:0:b0:66d:2140:1f88 with SMTP id u6-20020ad45aa6000000b0066d21401f88mr2912148qvg.5.1698119552265; Mon, 23 Oct 2023 20:52:32 -0700 (PDT) Received: from localhost ([70.22.175.108]) by smtp.gmail.com with ESMTPSA id l15-20020ad4452f000000b0066cf2423c79sm3357639qvu.139.2023.10.23.20.52.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Oct 2023 20:52:31 -0700 (PDT) Date: Mon, 23 Oct 2023 23:52:31 -0400 Message-ID: <1e9658bed9b583c9d6cf07c13253cf8f.paul@paul-moore.com> From: Paul Moore To: Fan Wu , corbet@lwn.net, zohar@linux.ibm.com, jmorris@namei.org, serge@hallyn.com, tytso@mit.edu, ebiggers@kernel.org, axboe@kernel.dk, agk@redhat.com, snitzer@kernel.org, eparis@redhat.com Cc: linux-doc@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fscrypt@vger.kernel.org, linux-block@vger.kernel.org, dm-devel@redhat.com, audit@vger.kernel.org, roberto.sassu@huawei.com, linux-kernel@vger.kernel.org, Deven Bowers , Fan Wu Subject: Re: [PATCH RFC v11 13/19] dm verity: consume root hash digest and signature data via LSM hook References: <1696457386-3010-14-git-send-email-wufan@linux.microsoft.com> In-Reply-To: <1696457386-3010-14-git-send-email-wufan@linux.microsoft.com> Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org On Oct 4, 2023 Fan Wu wrote: > > dm-verity provides a strong guarantee of a block device's integrity. As > a generic way to check the integrity of a block device, it provides > those integrity guarantees to its higher layers, including the filesystem > level. > > An LSM that control access to a resource on the system based on the > available integrity claims can use this transitive property of > dm-verity, by querying the underlying block_device of a particular > file. > > The digest and signature information need to be stored in the block > device to fulfill the next requirement of authorization via LSM policy. > This will enable the LSM to perform revocation of devices that are still > mounted, prohibiting execution of files that are no longer authorized > by the LSM in question. > > This patch added two security hook calls in dm-verity to save the > dm-verity roothash and the roothash signature to the block device's > LSM blobs. > > Signed-off-by: Deven Bowers > Signed-off-by: Fan Wu > --- > v2: > + No Changes > > v3: > + No changes > > v4: > + No changes > > v5: > + No changes > > v6: > + Fix an improper cleanup that can result in > a leak > > v7: > + Squash patch 08/12, 10/12 to [11/16] > + Use part0 for block_device, to retrieve the block_device, when > calling security_bdev_setsecurity > > v8: > + Undo squash of 08/12, 10/12 - separating drivers/md/ from > security/ & block/ > + Use common-audit function for dmverity_signature. > + Change implementation for storing the dm-verity digest to use the > newly introduced dm_verity_digest structure introduced in patch > 14/20. > + Create new structure, dm_verity_digest, containing digest algorithm, > size, and digest itself to pass to the LSM layer. V7 was missing the > algorithm. > + Create an associated public header containing this new structure and > the key values for the LSM hook, specific to dm-verity. > + Additional information added to commit, discussing the layering of > the changes and how the information passed will be used. > > v9: > + No changes > > v10: > + No changes > > v11: > + Add an optional field to save signature > + Move the security hook call to the new finalize hook > --- > drivers/md/dm-verity-target.c | 71 +++++++++++++++++++++++++++++++++++ > drivers/md/dm-verity.h | 6 +++ > include/linux/dm-verity.h | 19 ++++++++++ > 3 files changed, 96 insertions(+) > create mode 100644 include/linux/dm-verity.h We need an ACK from Alasdair and/or Mike on this too. > diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c > index 80673b66c194..db58b53649e3 100644 > --- a/drivers/md/dm-verity-target.c > +++ b/drivers/md/dm-verity-target.c > @@ -13,6 +13,7 @@ > * access behavior. > */ > > +#include "dm-core.h" > #include "dm-verity.h" > #include "dm-verity-fec.h" > #include "dm-verity-verify-sig.h" > @@ -22,6 +23,9 @@ > #include > #include > #include > +#include > +#include > +#include > > #define DM_MSG_PREFIX "verity" > > @@ -952,6 +956,17 @@ static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) > blk_limits_io_min(limits, limits->logical_block_size); > } > > +#ifdef CONFIG_IPE_PROP_DM_VERITY > +static void verity_free_sig(struct dm_verity *v) > +{ > + kfree(v->root_digest_sig); > +} > +#else > +static inline void verity_free_sig(struct dm_verity *v) > +{ > +} > +#endif /* CONFIG_IPE_PROP_DM_VERITY */ > + > static void verity_dtr(struct dm_target *ti) > { > struct dm_verity *v = ti->private; > @@ -966,6 +981,7 @@ static void verity_dtr(struct dm_target *ti) > kfree(v->salt); > kfree(v->root_digest); > kfree(v->zero_digest); > + verity_free_sig(v); > > if (v->tfm) > crypto_free_ahash(v->tfm); > @@ -1157,6 +1173,25 @@ static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, > return r; > } > > +#ifdef CONFIG_IPE_PROP_DM_VERITY > +static int verity_init_sig(struct dm_verity *v, const void *sig, > + size_t sig_size) > +{ > + v->sig_size = sig_size; > + v->root_digest_sig = kmalloc(v->sig_size, GFP_KERNEL); > + if (!v->root_digest) > + return -ENOMEM; > + > + return 0; > +} > +#else > +static inline int verity_init_sig(struct dm_verity *v, const void *sig, > + size_t sig_size) > +{ > + return 0; > +} > +#endif /* CONFIG_IPE_PROP_DM_VERITY */ > + > /* > * Target parameters: > * The current format is version 1. > @@ -1365,6 +1400,13 @@ static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv) > ti->error = "Root hash verification failed"; > goto bad; > } > + > + r = verity_init_sig(v, verify_args.sig, verify_args.sig_size); > + if (r < 0) { > + ti->error = "Cannot allocate root digest signature"; > + goto bad; > + } > + > v->hash_per_block_bits = > __fls((1 << v->hash_dev_block_bits) / v->digest_size); > > @@ -1501,6 +1543,32 @@ int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned i > return 0; > } > > +#ifdef CONFIG_IPE_PROP_DM_VERITY > +static int verity_finalize(struct dm_target *ti) > +{ > + struct block_device *bdev; > + struct dm_verity_digest root_digest; > + struct dm_verity *v; > + int r; > + > + v = ti->private; > + bdev = dm_table_get_md(ti->table)->disk->part0; > + root_digest.digest = v->root_digest; > + root_digest.digest_len = v->digest_size; > + root_digest.algo = v->alg_name; > + > + r = security_bdev_setsecurity(bdev, DM_VERITY_ROOTHASH_SEC_NAME, &root_digest, > + sizeof(root_digest)); > + if (r) > + return r; > + > + return security_bdev_setsecurity(bdev, > + DM_VERITY_SIGNATURE_SEC_NAME, > + v->root_digest_sig, > + v->sig_size); > +} > +#endif /* CONFIG_IPE_PROP_DM_VERITY */ > + > static struct target_type verity_target = { > .name = "verity", > .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE, > @@ -1513,6 +1581,9 @@ static struct target_type verity_target = { > .prepare_ioctl = verity_prepare_ioctl, > .iterate_devices = verity_iterate_devices, > .io_hints = verity_io_hints, > +#ifdef CONFIG_IPE_PROP_DM_VERITY > + .finalize = verity_finalize, > +#endif /* CONFIG_IPE_PROP_DM_VERITY */ > }; > module_dm(verity); > > diff --git a/drivers/md/dm-verity.h b/drivers/md/dm-verity.h > index 2f555b420367..a093d4a54615 100644 > --- a/drivers/md/dm-verity.h > +++ b/drivers/md/dm-verity.h > @@ -42,6 +42,9 @@ struct dm_verity { > u8 *root_digest; /* digest of the root block */ > u8 *salt; /* salt: its size is salt_size */ > u8 *zero_digest; /* digest for a zero block */ > +#ifdef CONFIG_IPE_PROP_DM_VERITY > + u8 *root_digest_sig; /* digest signature of the root block */ > +#endif /* CONFIG_IPE_PROP_DM_VERITY */ > unsigned int salt_size; > sector_t data_start; /* data offset in 512-byte sectors */ > sector_t hash_start; /* hash start in blocks */ > @@ -55,6 +58,9 @@ struct dm_verity { > bool hash_failed:1; /* set if hash of any block failed */ > bool use_tasklet:1; /* try to verify in tasklet before work-queue */ > unsigned int digest_size; /* digest size for the current hash algorithm */ > +#ifdef CONFIG_IPE_PROP_DM_VERITY > + unsigned int sig_size; /* digest signature size */ > +#endif /* CONFIG_IPE_PROP_DM_VERITY */ > unsigned int ahash_reqsize;/* the size of temporary space for crypto */ > enum verity_mode mode; /* mode for handling verification errors */ > unsigned int corrupted_errs;/* Number of errors for corrupted blocks */ > diff --git a/include/linux/dm-verity.h b/include/linux/dm-verity.h > new file mode 100644 > index 000000000000..bb0413d55d72 > --- /dev/null > +++ b/include/linux/dm-verity.h > @@ -0,0 +1,19 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > + > +#ifndef _LINUX_DM_VERITY_H > +#define _LINUX_DM_VERITY_H > + > +#include > +#include > +#include > + > +struct dm_verity_digest { > + const char *algo; > + const u8 *digest; > + size_t digest_len; > +}; > + > +#define DM_VERITY_SIGNATURE_SEC_NAME DM_NAME ".verity-signature" > +#define DM_VERITY_ROOTHASH_SEC_NAME DM_NAME ".verity-roothash" > + > +#endif /* _LINUX_DM_VERITY_H */ > -- > 2.25.1 -- paul-moore.com