From patchwork Wed May 4 19:54:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthias Kaehlcke X-Patchwork-Id: 12838567 X-Patchwork-Delegate: snitzer@redhat.com 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 us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5C3AFC433FE for ; Wed, 4 May 2022 21:23:35 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-592-y2YQ3js1O5yzRbOtlb0LCg-1; Wed, 04 May 2022 17:23:33 -0400 X-MC-Unique: y2YQ3js1O5yzRbOtlb0LCg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 956911857F19; Wed, 4 May 2022 21:23:30 +0000 (UTC) Received: from mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (unknown [10.30.29.100]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8081AC28112; Wed, 4 May 2022 21:23:30 +0000 (UTC) Received: from mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (localhost [IPv6:::1]) by mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (Postfix) with ESMTP id 0FB1E194707A; Wed, 4 May 2022 21:23:29 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) by mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (Postfix) with ESMTP id F1A791947046 for ; Wed, 4 May 2022 19:54:30 +0000 (UTC) Received: by smtp.corp.redhat.com (Postfix) id E4382415F5E; Wed, 4 May 2022 19:54:30 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mimecast09.extmail.prod.ext.rdu2.redhat.com [10.11.55.25]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E058A403373 for ; Wed, 4 May 2022 19:54:30 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-1.mimecast.com [205.139.110.61]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C84E129ABA06 for ; Wed, 4 May 2022 19:54:30 +0000 (UTC) Received: from mail-pj1-f46.google.com (mail-pj1-f46.google.com [209.85.216.46]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-522-kKBw_RUlMX6sn20DoOzeHw-1; Wed, 04 May 2022 15:54:26 -0400 X-MC-Unique: kKBw_RUlMX6sn20DoOzeHw-1 Received: by mail-pj1-f46.google.com with SMTP id cq17-20020a17090af99100b001dc0386cd8fso2136873pjb.5 for ; Wed, 04 May 2022 12:54:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=5CetlpCftC8fa22AwQ7f9noDAbp04u3fxXYOBJDWXdo=; b=1KhhHlVfY880t0iGfn95vEtnbj30KxeIYPhzYYDlESoRDB+y+XNE4UFHh6qIqVX88I lF8dgABsBqc2kiR1btoG5wMYsgjz+0HPaVZmzT2wjfhcrKvwkYS/dGta8wEtCR+JRips hzIBUwxcjF8V6zouvLIbekF45E4BPkuw4JaAOMBlWDDIFDYsQLqQrkpIjzvjqL3Hq/ow 0MCJNiD02ITXaG9YpQGBNT/dSY5BLXVp5jqRhC0KVL3Cy+xhQN+y+iBLDDFQisQeNGWE nX2WweMX6NFrG8UVLzaAbzNdpIcBBIunl3B9Il/h+1bkf+BpHup/t6a2+f5UXupa2V29 iCWg== X-Gm-Message-State: AOAM533ZzRKkeSK0nimF6BI3m7Xe2uZom55IYWjPcsPyVtJzPlXE2TIp GH7W3IDAFjD7kJWH9qQA4ht1X9LybOXTyQ== X-Google-Smtp-Source: ABdhPJzmCKD4KIjLDv8vNDJK4ppeaWC2YAVRNAFyqVpurA+XTRKpw2HAvCD1vyC3w23XbEThwD8IPQ== X-Received: by 2002:a17:902:ecc8:b0:15e:9e46:cb7e with SMTP id a8-20020a170902ecc800b0015e9e46cb7emr18203039plh.111.1651694065547; Wed, 04 May 2022 12:54:25 -0700 (PDT) Received: from localhost ([2620:15c:202:201:35b6:c77b:be04:3bd5]) by smtp.gmail.com with UTF8SMTPSA id n5-20020aa79045000000b0050dc7628143sm8586582pfo.29.2022.05.04.12.54.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 May 2022 12:54:25 -0700 (PDT) From: Matthias Kaehlcke To: Alasdair Kergon , Mike Snitzer , Kees Cook , James Morris , "Serge E . Hallyn" Date: Wed, 4 May 2022 12:54:17 -0700 Message-Id: <20220504125404.v3.1.I3e928575a23481121e73286874c4c2bdb403355d@changeid> In-Reply-To: <20220504195419.1143099-1-mka@chromium.org> References: <20220504195419.1143099-1-mka@chromium.org> MIME-Version: 1.0 X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.85 on 10.11.54.10 X-Mailman-Approved-At: Wed, 04 May 2022 21:23:25 +0000 Subject: [dm-devel] [PATCH v3 1/3] dm: Add verity helpers for LoadPin X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Douglas Anderson , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, Song Liu , dm-devel@redhat.com, Matthias Kaehlcke Errors-To: dm-devel-bounces@redhat.com Sender: "dm-devel" X-Scanned-By: MIMEDefang 2.85 on 10.11.54.8 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com LoadPin limits loading of kernel modules, firmware and certain other files to a 'pinned' file system (typically a read-only rootfs). To provide more flexibility LoadPin is being extended to also allow loading these files from trusted dm-verity devices. For that purpose LoadPin can be provided with a list of verity root digests that it should consider as trusted. Add a bunch of helpers to allow LoadPin to check whether a DM device is a trusted verity device. The new functions broadly fall in two categories: those that need access to verity internals (like the root digest), and the 'glue' between LoadPin and verity. The new file dm-verity-loadpin.c contains the glue functions. Signed-off-by: Matthias Kaehlcke --- Changes in v3: - none Changes in v2: - none drivers/md/Makefile | 6 +++ drivers/md/dm-verity-loadpin.c | 80 +++++++++++++++++++++++++++++++ drivers/md/dm-verity-target.c | 33 +++++++++++++ drivers/md/dm-verity.h | 4 ++ include/linux/dm-verity-loadpin.h | 27 +++++++++++ 5 files changed, 150 insertions(+) create mode 100644 drivers/md/dm-verity-loadpin.c create mode 100644 include/linux/dm-verity-loadpin.h diff --git a/drivers/md/Makefile b/drivers/md/Makefile index 0454b0885b01..e12cd004d375 100644 --- a/drivers/md/Makefile +++ b/drivers/md/Makefile @@ -100,6 +100,12 @@ ifeq ($(CONFIG_IMA),y) dm-mod-objs += dm-ima.o endif +ifeq ($(CONFIG_DM_VERITY),y) +ifeq ($(CONFIG_SECURITY_LOADPIN),y) +dm-mod-objs += dm-verity-loadpin.o +endif +endif + ifeq ($(CONFIG_DM_VERITY_FEC),y) dm-verity-objs += dm-verity-fec.o endif diff --git a/drivers/md/dm-verity-loadpin.c b/drivers/md/dm-verity-loadpin.c new file mode 100644 index 000000000000..972ca93a2231 --- /dev/null +++ b/drivers/md/dm-verity-loadpin.c @@ -0,0 +1,80 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include +#include +#include + +#include "dm.h" +#include "dm-verity.h" + +static struct list_head *trusted_root_digests; + +/* + * Sets the root digests of verity devices which LoadPin considers as trusted. + * + * This function must only be called once. + */ +void dm_verity_loadpin_set_trusted_root_digests(struct list_head *digests) +{ + if (!trusted_root_digests) + trusted_root_digests = digests; + else + pr_warn("verity root digests trusted by LoadPin are already set!!!\n"); +} + +static bool is_trusted_verity_target(struct dm_target *ti) +{ + u8 *root_digest; + unsigned int digest_size; + struct trusted_root_digest *trd; + bool trusted = false; + + if (!dm_is_verity_target(ti)) + return false; + + if (dm_verity_get_root_digest(ti, &root_digest, &digest_size)) + return false; + + list_for_each_entry(trd, trusted_root_digests, node) { + if ((trd->len == digest_size) && + !memcmp(trd->data, root_digest, digest_size)) { + trusted = true; + break; + } + } + + kfree(root_digest); + + return trusted; +} + +/* + * Determines whether a mapped device is a verity device that is trusted + * by LoadPin. + */ +bool dm_verity_loadpin_is_md_trusted(struct mapped_device *md) +{ + int srcu_idx; + struct dm_table *table; + unsigned int num_targets; + bool trusted = false; + int i; + + if (!trusted_root_digests || list_empty(trusted_root_digests)) + return false; + + table = dm_get_live_table(md, &srcu_idx); + num_targets = dm_table_get_num_targets(table); + for (i = 0; i < num_targets; i++) { + struct dm_target *ti = dm_table_get_target(table, i); + + if (is_trusted_verity_target(ti)) { + trusted = true; + break; + } + } + + dm_put_live_table(md, srcu_idx); + + return trusted; +} diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c index 80133aae0db3..6f07b849fcb2 100644 --- a/drivers/md/dm-verity-target.c +++ b/drivers/md/dm-verity-target.c @@ -19,6 +19,7 @@ #include #include #include +#include #define DM_MSG_PREFIX "verity" @@ -1310,6 +1311,38 @@ static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv) return r; } +/* + * Check whether a DM target is a verity target. + */ +bool dm_is_verity_target(struct dm_target *ti) +{ + return ti->type->module == THIS_MODULE; +} +EXPORT_SYMBOL_GPL(dm_is_verity_target); + +/* + * Get the root digest of a verity target. + * + * Returns a copy of the root digest, the caller is responsible for + * freeing the memory of the digest. + */ +int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size) +{ + struct dm_verity *v = ti->private; + + if (!dm_is_verity_target(ti)) + return -EINVAL; + + *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL); + if (*root_digest == NULL) + return -ENOMEM; + + *digest_size = v->digest_size; + + return 0; +} +EXPORT_SYMBOL_GPL(dm_verity_get_root_digest); + static struct target_type verity_target = { .name = "verity", .version = {1, 8, 0}, diff --git a/drivers/md/dm-verity.h b/drivers/md/dm-verity.h index 4e769d13473a..c832cc3e3d24 100644 --- a/drivers/md/dm-verity.h +++ b/drivers/md/dm-verity.h @@ -129,4 +129,8 @@ extern int verity_hash(struct dm_verity *v, struct ahash_request *req, extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, sector_t block, u8 *digest, bool *is_zero); +extern bool dm_is_verity_target(struct dm_target *ti); +extern int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, + unsigned int *digest_size); + #endif /* DM_VERITY_H */ diff --git a/include/linux/dm-verity-loadpin.h b/include/linux/dm-verity-loadpin.h new file mode 100644 index 000000000000..12a86911d05a --- /dev/null +++ b/include/linux/dm-verity-loadpin.h @@ -0,0 +1,27 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef __LINUX_DM_VERITY_LOADPIN_H +#define __LINUX_DM_VERITY_LOADPIN_H + +#include + +struct mapped_device; + +struct trusted_root_digest { + u8 *data; + unsigned int len; + struct list_head node; +}; + +#if IS_ENABLED(CONFIG_SECURITY_LOADPIN) && IS_BUILTIN(CONFIG_DM_VERITY) +void dm_verity_loadpin_set_trusted_root_digests(struct list_head *digests); +bool dm_verity_loadpin_is_md_trusted(struct mapped_device *md); +#else +static inline void dm_verity_loadpin_set_trusted_root_digests(struct list_head *digests) {} +static inline bool dm_verity_loadpin_is_md_trusted(struct mapped_device *md) +{ + return false; +} +#endif + +#endif /* __LINUX_DM_LOADPIN_H */ From patchwork Wed May 4 19:54:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthias Kaehlcke X-Patchwork-Id: 12838564 X-Patchwork-Delegate: snitzer@redhat.com 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 us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 93E74C433FE for ; Wed, 4 May 2022 21:23:32 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-675-AUxKj4UmMjSkof-fatbCKw-1; Wed, 04 May 2022 17:23:28 -0400 X-MC-Unique: AUxKj4UmMjSkof-fatbCKw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id F27893C0D189; 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Hallyn" Date: Wed, 4 May 2022 12:54:18 -0700 Message-Id: <20220504125404.v3.2.I01c67af41d2f6525c6d023101671d7339a9bc8b5@changeid> In-Reply-To: <20220504195419.1143099-1-mka@chromium.org> References: <20220504195419.1143099-1-mka@chromium.org> MIME-Version: 1.0 X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.85 on 10.11.54.10 X-Mailman-Approved-At: Wed, 04 May 2022 21:23:25 +0000 Subject: [dm-devel] [PATCH v3 2/3] LoadPin: Enable loading from trusted dm-verity devices X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Douglas Anderson , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, Song Liu , dm-devel@redhat.com, Matthias Kaehlcke Errors-To: dm-devel-bounces@redhat.com Sender: "dm-devel" X-Scanned-By: MIMEDefang 2.84 on 10.11.54.1 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Extend LoadPin to allow loading of kernel files from trusted dm-verity [1] devices. This change adds the concept of trusted verity devices to LoadPin. LoadPin maintains a list of root digests of verity devices it considers trusted. Userspace can populate this list through an ioctl on the new LoadPin securityfs entry 'dm-verity'. The ioctl receives a file descriptor of a file with verity digests as parameter. Verity reads the digests from this file after confirming that the file is located on the pinned root. The list of trusted digests can only be set up once, which is typically done at boot time. When a kernel file is read LoadPin first checks (as usual) whether the file is located on the pinned root, if so the file can be loaded. Otherwise, if the verity extension is enabled, LoadPin determines whether the file is located on a verity backed device and whether the root digest of that device is in the list of trusted digests. The file can be loaded if the verity device has a trusted root digest. Background: As of now LoadPin restricts loading of kernel files to a single pinned filesystem, typically the rootfs. This works for many systems, however it can result in a bloated rootfs (and OTA updates) on platforms where multiple boards with different hardware configurations use the same rootfs image. Especially when 'optional' files are large it may be preferable to download/install them only when they are actually needed by a given board. Chrome OS uses Downloadable Content (DLC) [2] to deploy certain 'packages' at runtime. As an example a DLC package could contain firmware for a peripheral that is not present on all boards. DLCs use dm-verity to verify the integrity of the DLC content. [1] https://www.kernel.org/doc/html/latest/admin-guide/device-mapper/verity.html [2] https://chromium.googlesource.com/chromiumos/platform2/+/HEAD/dlcservice/docs/developer.md Signed-off-by: Matthias Kaehlcke Reported-by: kernel test robot --- Changes in v3: - added securityfs for LoadPin (currently only populated when CONFIG_SECURITY_LOADPIN_VERITY=y) - added uapi include for LoadPin - changed the interface for setting up the list of trusted digests from sysctl to ioctl on securityfs entry - added stub for loadpin_is_fs_trusted() to be used CONFIG_SECURITY_LOADPIN_VERITY is not select - depend on CONFIG_SECURITYFS instead of CONFIG_SYSTCL - updated Kconfig help - minor changes in read_trusted_verity_root_digests() - updated commit message Changes in v2: - userspace now passes the path of the file with the verity digests via systcl, instead of the digests themselves - renamed sysctl file to 'trusted_verity_root_digests_path' - have CONFIG_SECURITY_LOADPIN_VERITY depend on CONFIG_SYSCTL - updated Kconfig doc - updated commit message include/uapi/linux/loadpin.h | 19 ++++ security/loadpin/Kconfig | 16 +++ security/loadpin/loadpin.c | 184 ++++++++++++++++++++++++++++++++++- 3 files changed, 218 insertions(+), 1 deletion(-) create mode 100644 include/uapi/linux/loadpin.h diff --git a/include/uapi/linux/loadpin.h b/include/uapi/linux/loadpin.h new file mode 100644 index 000000000000..d303a582209b --- /dev/null +++ b/include/uapi/linux/loadpin.h @@ -0,0 +1,19 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +/* + * Copyright (c) 2022, Google LLC + */ + +#ifndef _UAPI_LINUX_LOOP_LOADPIN_H +#define _UAPI_LINUX_LOOP_LOADPIN_H + +#define LOADPIN_IOC_MAGIC 'L' + +/** + * LOADPIN_IOC_SET_TRUSTED_VERITY_DIGESTS - Set up the root digests of verity devices + * that loadpin should trust. + * + * Takes a file descriptor from which to read the root digests of trusted verity devices. + */ +#define LOADPIN_IOC_SET_TRUSTED_VERITY_DIGESTS _IOW(LOADPIN_IOC_MAGIC, 0x00, unsigned int) + +#endif /* _UAPI_LINUX_LOOP_LOADPIN_H */ diff --git a/security/loadpin/Kconfig b/security/loadpin/Kconfig index 91be65dec2ab..e319ca8e3f3d 100644 --- a/security/loadpin/Kconfig +++ b/security/loadpin/Kconfig @@ -18,3 +18,19 @@ config SECURITY_LOADPIN_ENFORCE If selected, LoadPin will enforce pinning at boot. If not selected, it can be enabled at boot with the kernel parameter "loadpin.enforce=1". + +config SECURITY_LOADPIN_VERITY + bool "Allow reading files from certain other filesystems that use dm-verity" + depends on DM_VERITY=y && SECURITYFS + help + If selected LoadPin can allow reading files from filesystems + that use dm-verity. LoadPin maintains a list of verity root + digests it considers trusted. A verity backed filesystem is + considered trusted if its root digest is found in the list + of trusted digests. + + The list of trusted verity can be populated through an ioctl + on the LoadPin securityfs entry 'dm-verity'. The ioctl + expects a file descriptor of a file with verity digests as + parameter. The file must be located on the pinned root and + contain a comma separated list of digests. diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c index b12f7d986b1e..c29ce562a366 100644 --- a/security/loadpin/loadpin.c +++ b/security/loadpin/loadpin.c @@ -18,6 +18,9 @@ #include #include /* current */ #include +#include +#include +#include static void report_load(const char *origin, struct file *file, char *operation) { @@ -43,6 +46,9 @@ static char *exclude_read_files[READING_MAX_ID]; static int ignore_read_file_id[READING_MAX_ID] __ro_after_init; static struct super_block *pinned_root; static DEFINE_SPINLOCK(pinned_root_spinlock); +#ifdef CONFIG_SECURITY_LOADPIN_VERITY +static LIST_HEAD(trusted_verity_root_digests); +#endif #ifdef CONFIG_SYSCTL @@ -118,6 +124,24 @@ static void loadpin_sb_free_security(struct super_block *mnt_sb) } } +#ifdef CONFIG_SECURITY_LOADPIN_VERITY +static bool loadpin_is_fs_trusted(struct super_block *sb) +{ + struct mapped_device *md = dm_get_md(sb->s_bdev->bd_dev); + bool trusted; + + if (!md) + return false; + + trusted = dm_verity_loadpin_is_md_trusted(md); + dm_put(md); + + return trusted; +} +#else +static inline bool loadpin_is_fs_trusted(struct super_block *sb) { return false; }; +#endif + static int loadpin_read_file(struct file *file, enum kernel_read_file_id id, bool contents) { @@ -174,7 +198,8 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id id, spin_unlock(&pinned_root_spinlock); } - if (IS_ERR_OR_NULL(pinned_root) || load_root != pinned_root) { + if (IS_ERR_OR_NULL(pinned_root) || + ((load_root != pinned_root) && !loadpin_is_fs_trusted(load_root))) { if (unlikely(!enforce)) { report_load(origin, file, "pinning-ignored"); return 0; @@ -240,6 +265,7 @@ static int __init loadpin_init(void) enforce ? "" : "not "); parse_exclude(); security_add_hooks(loadpin_hooks, ARRAY_SIZE(loadpin_hooks), "loadpin"); + return 0; } @@ -248,6 +274,162 @@ DEFINE_LSM(loadpin) = { .init = loadpin_init, }; +#ifdef CONFIG_SECURITY_LOADPIN_VERITY + +enum loadpin_securityfs_interface_index { + LOADPIN_DM_VERITY, +}; + +static int read_trusted_verity_root_digests(unsigned int fd) +{ + struct fd f; + void *data; + int rc; + char *p, *d; + + /* The list of trusted root digests can only be set up once */ + if (!list_empty(&trusted_verity_root_digests)) + return -EPERM; + + f = fdget(fd); + if (!f.file) + return -EINVAL; + + data = kzalloc(SZ_4K, GFP_KERNEL); + if (!data) { + rc = -ENOMEM; + goto err; + } + + rc = kernel_read_file(f.file, 0, &data, SZ_4K - 1, NULL, READING_POLICY); + if (rc < 0) + goto err; + + ((char *)data)[rc] = '\0'; + + p = strim(data); + while ((d = strsep(&p, ",")) != NULL) { + int len = strlen(d); + struct trusted_root_digest *trd; + + if (len % 2) { + rc = -EPROTO; + goto err; + } + + len /= 2; + + trd = kzalloc(sizeof(*trd), GFP_KERNEL); + if (!trd) { + rc = -ENOMEM; + goto err; + } + + trd->data = kzalloc(len, GFP_KERNEL); + if (!trd->data) { + kfree(trd); + rc = -ENOMEM; + goto err; + } + + if (hex2bin(trd->data, d, len)) { + kfree(trd); + kfree(trd->data); + rc = -EPROTO; + goto err; + } + + trd->len = len; + + list_add_tail(&trd->node, &trusted_verity_root_digests); + } + + kfree(data); + fdput(f); + + if (!list_empty(&trusted_verity_root_digests)) + dm_verity_loadpin_set_trusted_root_digests(&trusted_verity_root_digests); + + return 0; + +err: + kfree(data); + + { + struct trusted_root_digest *trd, *tmp; + + list_for_each_entry_safe(trd, tmp, &trusted_verity_root_digests, node) { + kfree(trd->data); + list_del(&trd->node); + kfree(trd); + } + } + + fdput(f); + + return rc; +} + +/******************************** securityfs ********************************/ + +static long dm_verity_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) +{ + void __user *uarg = (void __user *)arg; + unsigned int fd; + int rc; + + switch (cmd) { + case LOADPIN_IOC_SET_TRUSTED_VERITY_DIGESTS: + rc = copy_from_user(&fd, uarg, sizeof(fd)); + if (rc) + return rc; + + return read_trusted_verity_root_digests(fd); + + default: + return -EINVAL; + } +} + +static const struct file_operations loadpin_dm_verity_ops = { + .unlocked_ioctl = dm_verity_ioctl, + .compat_ioctl = compat_ptr_ioctl, +}; + +/** + * init_loadpin_securityfs - create the securityfs directory for LoadPin + * + * We can not put this method normally under the loadpin_init() code path since + * the security subsystem gets initialized before the vfs caches. + * + * Returns 0 if the securityfs directory creation was successful. + */ +static int __init init_loadpin_securityfs(void) +{ + struct dentry *loadpin_dir, *dentry; + + loadpin_dir = securityfs_create_dir("loadpin", NULL); + if (IS_ERR(loadpin_dir)) { + pr_err("LoadPin: could not create securityfs dir: %d\n", + PTR_ERR(loadpin_dir)); + return PTR_ERR(loadpin_dir); + } + + dentry = securityfs_create_file("dm-verity", 0600, loadpin_dir, + (void *)LOADPIN_DM_VERITY, &loadpin_dm_verity_ops); 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Wed, 04 May 2022 12:54:28 -0700 (PDT) Received: from localhost ([2620:15c:202:201:35b6:c77b:be04:3bd5]) by smtp.gmail.com with UTF8SMTPSA id t3-20020a17090aae0300b001d5e1b124a0sm3727332pjq.7.2022.05.04.12.54.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 May 2022 12:54:28 -0700 (PDT) From: Matthias Kaehlcke To: Alasdair Kergon , Mike Snitzer , Kees Cook , James Morris , "Serge E . Hallyn" Date: Wed, 4 May 2022 12:54:19 -0700 Message-Id: <20220504125404.v3.3.I5aca2dcc3b06de4bf53696cd21329dce8272b8aa@changeid> In-Reply-To: <20220504195419.1143099-1-mka@chromium.org> References: <20220504195419.1143099-1-mka@chromium.org> MIME-Version: 1.0 X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.85 on 10.11.54.8 X-Mailman-Approved-At: Wed, 04 May 2022 21:23:25 +0000 Subject: [dm-devel] [PATCH v3 3/3] dm: verity-loadpin: Use CONFIG_SECURITY_LOADPIN_VERITY for conditional compilation X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Douglas Anderson , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, Song Liu , dm-devel@redhat.com, Matthias Kaehlcke Errors-To: dm-devel-bounces@redhat.com Sender: "dm-devel" X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com The verity glue for LoadPin is only needed when CONFIG_SECURITY_LOADPIN_VERITY is set, use this option for conditional compilation instead of the combo of CONFIG_DM_VERITY and CONFIG_SECURITY_LOADPIN. Signed-off-by: Matthias Kaehlcke --- Changes in v3: - none Changes in v2: - none drivers/md/Makefile | 7 +------ include/linux/dm-verity-loadpin.h | 2 +- 2 files changed, 2 insertions(+), 7 deletions(-) diff --git a/drivers/md/Makefile b/drivers/md/Makefile index e12cd004d375..a96441752ec7 100644 --- a/drivers/md/Makefile +++ b/drivers/md/Makefile @@ -83,6 +83,7 @@ obj-$(CONFIG_DM_LOG_WRITES) += dm-log-writes.o obj-$(CONFIG_DM_INTEGRITY) += dm-integrity.o obj-$(CONFIG_DM_ZONED) += dm-zoned.o obj-$(CONFIG_DM_WRITECACHE) += dm-writecache.o +obj-$(CONFIG_SECURITY_LOADPIN_VERITY) += dm-verity-loadpin.o ifeq ($(CONFIG_DM_INIT),y) dm-mod-objs += dm-init.o @@ -100,12 +101,6 @@ ifeq ($(CONFIG_IMA),y) dm-mod-objs += dm-ima.o endif -ifeq ($(CONFIG_DM_VERITY),y) -ifeq ($(CONFIG_SECURITY_LOADPIN),y) -dm-mod-objs += dm-verity-loadpin.o -endif -endif - ifeq ($(CONFIG_DM_VERITY_FEC),y) dm-verity-objs += dm-verity-fec.o endif diff --git a/include/linux/dm-verity-loadpin.h b/include/linux/dm-verity-loadpin.h index 12a86911d05a..be63ac76f98d 100644 --- a/include/linux/dm-verity-loadpin.h +++ b/include/linux/dm-verity-loadpin.h @@ -13,7 +13,7 @@ struct trusted_root_digest { struct list_head node; }; -#if IS_ENABLED(CONFIG_SECURITY_LOADPIN) && IS_BUILTIN(CONFIG_DM_VERITY) +#if IS_ENABLED(CONFIG_SECURITY_LOADPIN_VERITY) void dm_verity_loadpin_set_trusted_root_digests(struct list_head *digests); bool dm_verity_loadpin_is_md_trusted(struct mapped_device *md); #else