From patchwork Tue Apr 26 21:31:08 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthias Kaehlcke X-Patchwork-Id: 12828744 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 E851FC433EF for ; Wed, 27 Apr 2022 12:14:54 +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-561-T3N2R-5dPCelxDe948go0Q-1; Wed, 27 Apr 2022 08:14:50 -0400 X-MC-Unique: T3N2R-5dPCelxDe948go0Q-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 01D4F86B8A1; Wed, 27 Apr 2022 12:14:49 +0000 (UTC) Received: from mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com [10.30.29.100]) by smtp.corp.redhat.com (Postfix) with ESMTP id 28B3214C1E82; Wed, 27 Apr 2022 12:14:47 +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 5FFBE1947062; Wed, 27 Apr 2022 12:14:45 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) by mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (Postfix) with ESMTP id BA9C519451F0 for ; Tue, 26 Apr 2022 21:31:32 +0000 (UTC) Received: by smtp.corp.redhat.com (Postfix) id ABF75111C4A0; Tue, 26 Apr 2022 21:31:32 +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 A70E5111C483 for ; Tue, 26 Apr 2022 21:31:23 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.120]) (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 66F502A5955B for ; Tue, 26 Apr 2022 21:31:23 +0000 (UTC) Received: from mail-pg1-f173.google.com (mail-pg1-f173.google.com [209.85.215.173]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-367-_yTm8qWLP7WTHDY9RXuluA-1; Tue, 26 Apr 2022 17:31:19 -0400 X-MC-Unique: _yTm8qWLP7WTHDY9RXuluA-1 Received: by mail-pg1-f173.google.com with SMTP id z21so9441142pgj.1 for ; Tue, 26 Apr 2022 14:31:19 -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=oklCy92EPimOxfFRDN0VLcpfYtlk8bEuVQrptcICGjQ=; b=8PV3kVAMdJmTBJBNHUumLl2jWXeF+kqm6PwTSRGHEFMwkmyBgTRtwB+bwuhQ+QltT5 nnC6S/0XpcZNe+SIKfL/B8VNj6ogV/ES9Li/2WyRalx9WYLZHmcduuynwDZGfjIJIkqH C9Dy6Dkm/g9HWhbc7XzwQ+MKsv/1lO7e07CkxLVFSFcycFktMpHxlKRTaHusRy0LpnTn eKgjECq38DedWY68YQtWTX56g9UBWbDunBuZo55rTBFn1wF2jjM6ofxfQpymlScMg3wu qgDUlzg52e3x6LGJMrEK67NO5TrcUj0FEyXEq3gUoKytm1sr3qyDxaxsPjX7laljuho6 wvow== X-Gm-Message-State: AOAM5308A8B4vv4DXYlVU87BSF84VbCi+2Ne4GkGmrOnbtGQNrOjas8A u6Rc3d0SupB9kjJ60qgqjsXjHg== X-Google-Smtp-Source: ABdhPJzUwQwV4e6Xy13BncRXONpdBAH4A4s7nHNnuR0F+ID7/PII+ISnk9adQiRXf94sAFkfyX9loQ== X-Received: by 2002:a63:2d46:0:b0:3c1:424a:2a90 with SMTP id t67-20020a632d46000000b003c1424a2a90mr582225pgt.35.1651008677493; Tue, 26 Apr 2022 14:31:17 -0700 (PDT) Received: from localhost ([2620:15c:202:201:eb63:4211:eb5d:f6b]) by smtp.gmail.com with UTF8SMTPSA id d141-20020a621d93000000b00505aa1026f1sm15919562pfd.51.2022.04.26.14.31.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 26 Apr 2022 14:31:17 -0700 (PDT) From: Matthias Kaehlcke To: Alasdair Kergon , Mike Snitzer , Kees Cook , James Morris , "Serge E . Hallyn" Date: Tue, 26 Apr 2022 14:31:08 -0700 Message-Id: <20220426143059.v2.1.I3e928575a23481121e73286874c4c2bdb403355d@changeid> In-Reply-To: <20220426213110.3572568-1-mka@chromium.org> References: <20220426213110.3572568-1-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 2.78 on 10.11.54.3 X-Mailman-Approved-At: Wed, 27 Apr 2022 12:14:17 +0000 Subject: [dm-devel] [PATCH v2 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: dm-devel@redhat.com, linux-kernel@vger.kernel.org, Douglas Anderson , linux-raid@vger.kernel.org, Song Liu , linux-security-module@vger.kernel.org, Matthias Kaehlcke Errors-To: dm-devel-bounces@redhat.com Sender: "dm-devel" X-Scanned-By: MIMEDefang 2.85 on 10.11.54.7 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 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..0638e61dba51 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 digests, 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 Tue Apr 26 21:31:09 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthias Kaehlcke X-Patchwork-Id: 12828747 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 8AF45C433FE for ; Wed, 27 Apr 2022 12:15:24 +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-372-ctA84d_DOoqTpFpdfuuZGA-1; Wed, 27 Apr 2022 08:15:19 -0400 X-MC-Unique: ctA84d_DOoqTpFpdfuuZGA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 54525833970; 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Hallyn" Date: Tue, 26 Apr 2022 14:31:09 -0700 Message-Id: <20220426143059.v2.2.I01c67af41d2f6525c6d023101671d7339a9bc8b5@changeid> In-Reply-To: <20220426213110.3572568-1-mka@chromium.org> References: <20220426213110.3572568-1-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 2.84 on 10.11.54.1 X-Mailman-Approved-At: Wed, 27 Apr 2022 12:14:17 +0000 Subject: [dm-devel] [PATCH v2 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: dm-devel@redhat.com, linux-kernel@vger.kernel.org, Douglas Anderson , linux-raid@vger.kernel.org, Song Liu , linux-security-module@vger.kernel.org, Matthias Kaehlcke Errors-To: dm-devel-bounces@redhat.com Sender: "dm-devel" X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 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. Userspace can use the new systl file 'loadpin/trusted_verity_root_digests_path' to provide LoadPin with the path of a file with a list of root digests from dm-verity devices that LoadPin should consider as trusted. This file must be located on the pinned root. 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. The path of the file with the trusted root digests can only be written once, which is typically done at boot time. 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 Reported-by: kernel test robot --- I'm still doubting what would be the best way to configure the list of trusted digests. The approach in v2 of writing a path through sysctl is flexible, but it also feels a bit odd. I did some experiments with passing a file descriptor through sysctl, but it's also odd and has its own issues. Passing the list through a kernel parameter seems hacky. A Kconfig string would work, but can be have issues when the same config is used for different platforms, where some may have trusted digests and others not. 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 security/loadpin/Kconfig | 16 +++ security/loadpin/loadpin.c | 200 ++++++++++++++++++++++++++++++++++++- 2 files changed, 215 insertions(+), 1 deletion(-) diff --git a/security/loadpin/Kconfig b/security/loadpin/Kconfig index 91be65dec2ab..20681dc4b8a5 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 && SYSCTL + 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. + + Userspace can populate the list of trusted digests by writing + the path of a file with the digests to the syctl file + 'trusted_verity_root_digests_path'. 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..db10b7ff6efd 100644 --- a/security/loadpin/loadpin.c +++ b/security/loadpin/loadpin.c @@ -18,6 +18,8 @@ #include #include /* current */ #include +#include +#include static void report_load(const char *origin, struct file *file, char *operation) { @@ -43,6 +45,10 @@ 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); +static const char *verity_digests_path; +#endif #ifdef CONFIG_SYSCTL @@ -65,6 +71,176 @@ static struct ctl_table loadpin_sysctl_table[] = { { } }; +#ifdef CONFIG_SECURITY_LOADPIN_VERITY + +static int loadpin_read_file(struct file *file, enum kernel_read_file_id id, + bool contents); + +static int read_trusted_verity_root_digests(struct file *file) +{ + void *data; + char *p, *d; + int err, rc; + + data = kzalloc(SZ_4K, GFP_KERNEL); + if (!data) + return -ENOMEM; + + rc = kernel_read_file(file, 0, &data, SZ_4K - 1, NULL, READING_POLICY); + if (rc < 0) + return rc; + + ((char *)data)[rc] = '\0'; + + p = strim(data); + while ((d = strsep(&p, ",")) != NULL) { + int len = strlen(d); + struct trusted_root_digest *trd; + + if (len % 2) { + err = -EPROTO; + goto free_mem; + } + + len /= 2; + + trd = kzalloc(sizeof(*trd), GFP_KERNEL); + if (!trd) { + err = -ENOMEM; + goto free_mem; + } + + trd->data = kzalloc(len, GFP_KERNEL); + if (!trd->data) { + kfree(trd); + err = -ENOMEM; + goto free_mem; + } + + if (hex2bin(trd->data, d, len)) { + kfree(trd); + err = -EPROTO; + goto free_mem; + } + + list_add_tail(&trd->node, &trusted_verity_root_digests); + + trd->len = len; + } + + kfree(data); + + return 0; + +free_mem: + 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); + } + } + + return err; +} + +static int proc_verity_digests(struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) +{ + struct ctl_table tbl = *table; + + if (write) { + int rc; + char *digests_path; + struct file *file; + + if (*ppos) + return -EINVAL; + + if (verity_digests_path != NULL) + return -EPERM; + + digests_path = kzalloc(tbl.maxlen, GFP_KERNEL); + if (!digests_path) + return -ENOMEM; + + tbl.data = digests_path; + + rc = proc_dostring(&tbl, write, buffer, lenp, ppos); + if (rc) { + kfree(digests_path); + return rc; + } + + /* only absolute paths are allowed */ + if (digests_path[0] != '/') { + kfree(digests_path); + return -EINVAL; + } + + file = filp_open(digests_path, O_RDONLY, 0); + if (IS_ERR(file)) { + int err = PTR_ERR(file); + + if (err == -ENOENT) { + kfree(digests_path); + return -EINVAL; + } + + return err; + } + + /* verify the root digests stem from a trusted file system */ + if (loadpin_read_file(file, READING_POLICY, true)) { + fput(file); + kfree(digests_path); + return -EPERM; + } + + rc = read_trusted_verity_root_digests(file); + fput(file); + if (rc) { + kfree(digests_path); + return rc; + } + + verity_digests_path = digests_path; + } else { + if (verity_digests_path) { + tbl.data = kzalloc(strlen(verity_digests_path) + 1, GFP_KERNEL); + strcpy(tbl.data, verity_digests_path); + } else { + tbl.data = kzalloc(1, GFP_KERNEL); + } + + proc_dostring(&tbl, write, buffer, lenp, ppos); + kfree(tbl.data); + } + + return 0; +} + +static struct ctl_table loadpin_sysctl_table_verity_digests[] = { + { + .procname = "trusted_verity_root_digests_path", + .maxlen = SZ_256, + .mode = 0644, + .proc_handler = proc_verity_digests, + }, + + { } +}; + +#else + +static struct ctl_table loadpin_sysctl_table_verity_digests[] = {}; + +#endif /* CONFIG_SECURITY_LOADPIN_VERITY */ + /* * This must be called after early kernel init, since then the rootdev * is available. @@ -118,6 +294,20 @@ static void loadpin_sb_free_security(struct super_block *mnt_sb) } } +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; +} + static int loadpin_read_file(struct file *file, enum kernel_read_file_id id, bool contents) { @@ -174,7 +364,8 @@ 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 +431,13 @@ static int __init loadpin_init(void) enforce ? "" : "not "); parse_exclude(); security_add_hooks(loadpin_hooks, ARRAY_SIZE(loadpin_hooks), "loadpin"); + + if (IS_ENABLED(CONFIG_SECURITY_LOADPIN_VERITY)) { + if (!register_sysctl_paths(loadpin_sysctl_path, + loadpin_sysctl_table_verity_digests)) + pr_notice("sysctl registration failed!\n"); + } + return 0; } From patchwork Tue Apr 26 21:31:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthias Kaehlcke X-Patchwork-Id: 12828766 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 7C0AAC433F5 for ; Wed, 27 Apr 2022 12:20:43 +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-180-Gjm33zpuOKCe8V3ol8n46g-1; Wed, 27 Apr 2022 08:20:39 -0400 X-MC-Unique: Gjm33zpuOKCe8V3ol8n46g-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 8092880270C; Wed, 27 Apr 2022 12:20:37 +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 6FB8B14C1E80; Wed, 27 Apr 2022 12:20:37 +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 D1ABE194704E; Wed, 27 Apr 2022 12:20:36 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) by mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (Postfix) with ESMTP id 6449219451F0 for ; Tue, 26 Apr 2022 21:31:26 +0000 (UTC) Received: by smtp.corp.redhat.com (Postfix) id 57F2914682C9; Tue, 26 Apr 2022 21:31:26 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mimecast05.extmail.prod.ext.rdu2.redhat.com [10.11.55.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 540A114682C2 for ; Tue, 26 Apr 2022 21:31:26 +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 3B93F801E80 for ; Tue, 26 Apr 2022 21:31:26 +0000 (UTC) Received: from mail-pj1-f51.google.com (mail-pj1-f51.google.com [209.85.216.51]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-318-d_tDnc8INfOII6Qdu9Gn8g-1; Tue, 26 Apr 2022 17:31:22 -0400 X-MC-Unique: d_tDnc8INfOII6Qdu9Gn8g-1 Received: by mail-pj1-f51.google.com with SMTP id w5-20020a17090aaf8500b001d74c754128so3350473pjq.0 for ; Tue, 26 Apr 2022 14:31:22 -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=dWxaD7L0u/h0y2dhkzttG4l+Tb/Huddvi0NADO8Lp2s=; b=Vnvzqz9ljxPp8a2qAnG48ctGbsgRMkvP7loUI/BE+uoebmd2GlEG3tUvSE2285NGnn ZVArA4X0nA0bqYJrF0kRFns8aZWVYmGgxo7zzQruAJMnhCRR7Ol+70PzwjfHvSyvTNKp KuFdUDdSoUxY1txpuEUUHP8efwQd04LhBKsSoI6ABbetCsA8C3ImoMQX44+9MInjT2l0 1w1m9snaxTWlGZK0LiM0M4KWB9xi/I5c9Y2q0yTITmGVYRuUvhT2T3eJvFGSD+gRQQzo h4owBMhyp7ilPqzibm5gtp38kxCgWhVOTH0UR3f7Hzp91NOlIDULrc932MjrG7ZZxV94 87Ow== X-Gm-Message-State: AOAM533tqNSBEjhDhJ6KzYgZTMP2Gwk2uF8gWt5wK+XrVMlSn/Hjhlbu SYxrTsB7ivM4YpTNWpwRpsgncA== X-Google-Smtp-Source: ABdhPJy4R5XtqAI2AVSwm6Ahikus8xa0rabLRQflKyRJPiBg1OerZzxzHWDe8RqGJ2mAUYofsSzeJw== X-Received: by 2002:a17:90b:2311:b0:1d9:277e:edad with SMTP id mt17-20020a17090b231100b001d9277eedadmr22722620pjb.190.1651008681490; Tue, 26 Apr 2022 14:31:21 -0700 (PDT) Received: from localhost ([2620:15c:202:201:eb63:4211:eb5d:f6b]) by smtp.gmail.com with UTF8SMTPSA id z8-20020aa785c8000000b005060d2d7085sm16015202pfn.151.2022.04.26.14.31.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 26 Apr 2022 14:31:21 -0700 (PDT) From: Matthias Kaehlcke To: Alasdair Kergon , Mike Snitzer , Kees Cook , James Morris , "Serge E . Hallyn" Date: Tue, 26 Apr 2022 14:31:10 -0700 Message-Id: <20220426143059.v2.3.I5aca2dcc3b06de4bf53696cd21329dce8272b8aa@changeid> In-Reply-To: <20220426213110.3572568-1-mka@chromium.org> References: <20220426213110.3572568-1-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 10.11.54.7 X-Mailman-Approved-At: Wed, 27 Apr 2022 12:14:17 +0000 Subject: [dm-devel] [PATCH v2 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: dm-devel@redhat.com, linux-kernel@vger.kernel.org, Douglas Anderson , linux-raid@vger.kernel.org, Song Liu , linux-security-module@vger.kernel.org, Matthias Kaehlcke Errors-To: dm-devel-bounces@redhat.com Sender: "dm-devel" X-Scanned-By: MIMEDefang 2.85 on 10.11.54.7 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 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