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 AA26EC433FE for ; Mon, 18 Apr 2022 21:16:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347989AbiDRVS6 (ORCPT ); Mon, 18 Apr 2022 17:18:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53194 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237880AbiDRVS4 (ORCPT ); Mon, 18 Apr 2022 17:18:56 -0400 Received: from mail-pg1-x52f.google.com (mail-pg1-x52f.google.com [IPv6:2607:f8b0:4864:20::52f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F17842CE18 for ; Mon, 18 Apr 2022 14:16:09 -0700 (PDT) Received: by mail-pg1-x52f.google.com with SMTP id bg9so21078285pgb.9 for ; Mon, 18 Apr 2022 14:16:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=z7MNQdhfJevonqU1gbIMWRC7hAVlhGusKX2oocNDGwg=; b=FAuNNboCO/FPFJkwp5PqYbA8WCixhPEvKA7SW9KlYH7NB9BrlBhq3b1FZlX0I8Xvbm 7ci+OWsvOyoWgrqCnm7OdfTfdp+eBZlK1swkaGRRPb36gVeU4JmZDP5PrtFk+SNkh7Vv kagm8tkFyJYvDDNS7r2EcUUpbk25fGTC1fcYE= 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=z7MNQdhfJevonqU1gbIMWRC7hAVlhGusKX2oocNDGwg=; b=nYMCIHYYDale9QIzK6mv7E8J+1ZakxrNSJy7Tyq7QH5+N55rtaamhxY1r/vtuZlwz1 LEBxYa4T4NfuE7XaGYYERsKLhWql5eqoYkgPlXM2pKFZROLCKf+PrTWNkzbrWybn+dfi RqTdbT5kvvIruSGUymRv2WxN7w5BoR1XVyeWUP0gHQBEb2uelQJVsSzmkgbF56+GR23s Pql2gDudobFOy+M51wODvf4XAdyR7/bttRKf1Z09rhR1nvY22TDPn4XNusiCgufvg0o5 2X/vN5TgC/dtXowCiH5Az/YonZ+U86f/rPI2PUT202OqFDi8yDnr4LiUZMsqHB0B8S4j oIaQ== X-Gm-Message-State: AOAM532/SpNeG0oqiHwm+XvLuEJ89OZzwacVSh4bRVRWXjCH3CQnT9sg B1JzU1MOQe/U96aMfT6JY+sAWw== X-Google-Smtp-Source: ABdhPJx4kToyubC6lCeN87zCNmuEOzpd1tCZwNVPjLaJyswe8LBMciizDAJKihUrNCpdY9/hLsvQhQ== X-Received: by 2002:a05:6a00:a26:b0:4fd:f9dd:549c with SMTP id p38-20020a056a000a2600b004fdf9dd549cmr14275958pfh.42.1650316569446; Mon, 18 Apr 2022 14:16:09 -0700 (PDT) Received: from localhost ([2620:15c:202:201:6b32:a0a5:ec32:c287]) by smtp.gmail.com with UTF8SMTPSA id n24-20020aa79058000000b0050612d0fe01sm13406325pfo.2.2022.04.18.14.16.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 Apr 2022 14:16:08 -0700 (PDT) From: Matthias Kaehlcke To: Alasdair Kergon , Mike Snitzer , Kees Cook , James Morris , "Serge E . Hallyn" Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, Song Liu , linux-security-module@vger.kernel.org, Douglas Anderson , dm-devel@redhat.com, Matthias Kaehlcke Subject: [PATCH 2/3] LoadPin: Enable loading from trusted dm-verity devices Date: Mon, 18 Apr 2022 14:15:58 -0700 Message-Id: <20220418141545.2.I01c67af41d2f6525c6d023101671d7339a9bc8b5@changeid> X-Mailer: git-send-email 2.36.0.rc0.470.gd361397f0d-goog In-Reply-To: <20220418211559.3832724-1-mka@chromium.org> References: <20220418211559.3832724-1-mka@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org 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' to provide LoadPin with a list of root digests from dm-verity devices that LoadPin should consider as trusted. 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 list of trusted root digests can only be written once (typically at boot time), to limit the possiblity of attackers setting up rogue verity devices and marking them as trusted. 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 --- security/loadpin/Kconfig | 11 +++ security/loadpin/loadpin.c | 168 ++++++++++++++++++++++++++++++++++++- 2 files changed, 178 insertions(+), 1 deletion(-) diff --git a/security/loadpin/Kconfig b/security/loadpin/Kconfig index 91be65dec2ab..cf3e6431e02d 100644 --- a/security/loadpin/Kconfig +++ b/security/loadpin/Kconfig @@ -18,3 +18,14 @@ 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 + help + If selected LoadPin can allow reading files from filesystems + that use dm-verity. A verity filesystem can be configured as + being trusted by LoadPin by writing its root digest to the + sysctl file 'trusted_verity_root_digests'. The sysctl file + can only be written once (typically at boot) and accepts a + list of comma separated digests. diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c index b12f7d986b1e..b9c174f8687d 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 bool verity_digests_set; +static LIST_HEAD(trusted_verity_root_digests); +#endif #ifdef CONFIG_SYSCTL @@ -65,6 +71,144 @@ static struct ctl_table loadpin_sysctl_table[] = { { } }; +#ifdef CONFIG_SECURITY_LOADPIN_VERITY + +static int proc_verity_root_digests(struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) +{ + struct trusted_root_digest *trd; + char *buf; + int rc; + + if (write) { + struct ctl_table tbl = *table; + char *p, *d; + + if (*ppos) + return -EINVAL; + + if (verity_digests_set) + return -EPERM; + + buf = kzalloc(tbl.maxlen, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + tbl.data = buf; + + rc = proc_dostring(&tbl, write, buffer, lenp, ppos); + if (rc) { + kfree(buf); + return rc; + } + + if (strlen(buf) == 0) { + verity_digests_set = true; + return false; + } + + p = buf; + while ((d = strsep(&p, ",")) != NULL) { + int len = strlen(d); + + if (len % 2) { + rc = -EINVAL; + goto err; + } + + len /= 2; + + trd = kzalloc(sizeof(*trd), GFP_KERNEL); + if (!trd) { + rc = -ENOMEM; + goto err; + } + + list_add_tail(&trd->node, &trusted_verity_root_digests); + + trd->data = kzalloc(len, GFP_KERNEL); + if (!trd->data) { + rc = -ENOMEM; + goto err; + } + + if (hex2bin(trd->data, d, len)) { + rc = -EINVAL; + goto err; + } + + trd->len = len; + } + + kfree(buf); + + if (!list_empty(&trusted_verity_root_digests)) { + dm_verity_loadpin_set_trusted_root_digests(&trusted_verity_root_digests); + verity_digests_set = true; + } + } else { + struct ctl_table tbl = { .maxlen = 0 }; + size_t off = 0; + + list_for_each_entry(trd, &trusted_verity_root_digests, node) { + /* two ASCII characters per byte and a comma / '\0' */ + tbl.maxlen += (trd->len * 2) + 1; + } + + tbl.data = kzalloc(tbl.maxlen, GFP_KERNEL); + + list_for_each_entry(trd, &trusted_verity_root_digests, node) { + int i; + + if (off > 0) { + snprintf(tbl.data + off, tbl.maxlen - off, ","); + off++; + } + + for (i = 0; i < trd->len; i++) { + snprintf(tbl.data + off, tbl.maxlen - off, "%02x", trd->data[i]); + off += 2; + } + } + + proc_dostring(&tbl, write, buffer, lenp, ppos); + kfree(tbl.data); + } + + return 0; + +err: + kfree(buf); + + { + struct trusted_root_digest *tmp; + + list_for_each_entry_safe(trd, tmp, &trusted_verity_root_digests, node) { + kfree(trd->data); + list_del(&trd->node); + kfree(trd); + } + } + + return rc; +} + +static struct ctl_table loadpin_sysctl_table_verity[] = { + { + .procname = "trusted_verity_root_digests", + .maxlen = SZ_4K, + .mode = 0644, + .proc_handler = proc_verity_root_digests, + }, + + { } +}; +#else + +static struct ctl_table loadpin_sysctl_table_verity[] = {}; + +#endif /* CONFIG_SECURITY_LOADPIN_VERITY */ + /* * This must be called after early kernel init, since then the rootdev * is available. @@ -118,6 +262,20 @@ 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 +332,8 @@ 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 +399,13 @@ 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)) + pr_notice("sysctl registration failed!\n"); + } + return 0; } -- 2.36.0.rc0.470.gd361397f0d-goog 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 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 B5885C433F5 for ; Tue, 19 Apr 2022 06:10:38 +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-280-L4t7yW_TNJqyQp9yCHltLA-1; Tue, 19 Apr 2022 02:10:34 -0400 X-MC-Unique: L4t7yW_TNJqyQp9yCHltLA-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 EC90786B8AB; Tue, 19 Apr 2022 06:10:31 +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 D815FC52D95; Tue, 19 Apr 2022 06:10:31 +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 C8D8A1940371; Tue, 19 Apr 2022 06:10:28 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) by mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (Postfix) with ESMTP id 082EA1947BBD for ; Mon, 18 Apr 2022 21:16:13 +0000 (UTC) Received: by smtp.corp.redhat.com (Postfix) id D902C454D64; Mon, 18 Apr 2022 21:16:12 +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 D4AB5440ABF for ; Mon, 18 Apr 2022 21:16:12 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [205.139.110.120]) (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 B8BD2299E76E for ; Mon, 18 Apr 2022 21:16:12 +0000 (UTC) Received: from mail-pg1-f181.google.com (mail-pg1-f181.google.com [209.85.215.181]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-652-_dUK8ILmPJa0HaT1E-G8yw-1; Mon, 18 Apr 2022 17:16:10 -0400 X-MC-Unique: _dUK8ILmPJa0HaT1E-G8yw-1 Received: by mail-pg1-f181.google.com with SMTP id t13so21095310pgn.8 for ; Mon, 18 Apr 2022 14:16:10 -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=z7MNQdhfJevonqU1gbIMWRC7hAVlhGusKX2oocNDGwg=; b=lg0WLf32sT2QgqnCa6O1IqF0j/5KVBeghQ1zOi90u0rGsr79NwEqkK+Em2XhYkUcPD CVnjfYNWrzY91AQS5cfzT6cetBOWGnZtt7jdJqVX04NZ+5qmf0maqN4vxJI/a2mNWKKi kidqvNHjMWULQpUO4sdcfH8oeR/h6GMp3Z3tJeOgV8IINvVJdAqYnqUS0iPVlhwpZF94 cH4nkFbdLw3WvOWuAlwCtlAGghDRVUiSppcGTS5QLHYN/kn7PXDiHnX1+qQh0b3WaVLv T/TkMCoPk4lLjH1e3TyhnRx+HPbKDNlV/z45ThTz0Gp8lcsYxNaESOik18n+jefNeOIW SO1Q== X-Gm-Message-State: AOAM532SRmzOMOpJRnBWdHZkEri6zSSXf9lgJw9/tMS/5GWxtH9dJj1s M/fk7pYvZAdppz2J+wYpjLqUCkCwpNeO7w== X-Google-Smtp-Source: ABdhPJx4kToyubC6lCeN87zCNmuEOzpd1tCZwNVPjLaJyswe8LBMciizDAJKihUrNCpdY9/hLsvQhQ== X-Received: by 2002:a05:6a00:a26:b0:4fd:f9dd:549c with SMTP id p38-20020a056a000a2600b004fdf9dd549cmr14275958pfh.42.1650316569446; Mon, 18 Apr 2022 14:16:09 -0700 (PDT) Received: from localhost ([2620:15c:202:201:6b32:a0a5:ec32:c287]) by smtp.gmail.com with UTF8SMTPSA id n24-20020aa79058000000b0050612d0fe01sm13406325pfo.2.2022.04.18.14.16.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 Apr 2022 14:16:08 -0700 (PDT) From: Matthias Kaehlcke To: Alasdair Kergon , Mike Snitzer , Kees Cook , James Morris , "Serge E . Hallyn" Date: Mon, 18 Apr 2022 14:15:58 -0700 Message-Id: <20220418141545.2.I01c67af41d2f6525c6d023101671d7339a9bc8b5@changeid> In-Reply-To: <20220418211559.3832724-1-mka@chromium.org> References: <20220418211559.3832724-1-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 10.11.54.9 X-Mailman-Approved-At: Tue, 19 Apr 2022 06:10:27 +0000 Subject: [dm-devel] [PATCH 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 2.85 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 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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' to provide LoadPin with a list of root digests from dm-verity devices that LoadPin should consider as trusted. 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 list of trusted root digests can only be written once (typically at boot time), to limit the possiblity of attackers setting up rogue verity devices and marking them as trusted. 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 --- security/loadpin/Kconfig | 11 +++ security/loadpin/loadpin.c | 168 ++++++++++++++++++++++++++++++++++++- 2 files changed, 178 insertions(+), 1 deletion(-) diff --git a/security/loadpin/Kconfig b/security/loadpin/Kconfig index 91be65dec2ab..cf3e6431e02d 100644 --- a/security/loadpin/Kconfig +++ b/security/loadpin/Kconfig @@ -18,3 +18,14 @@ 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 + help + If selected LoadPin can allow reading files from filesystems + that use dm-verity. A verity filesystem can be configured as + being trusted by LoadPin by writing its root digest to the + sysctl file 'trusted_verity_root_digests'. The sysctl file + can only be written once (typically at boot) and accepts a + list of comma separated digests. diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c index b12f7d986b1e..b9c174f8687d 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 bool verity_digests_set; +static LIST_HEAD(trusted_verity_root_digests); +#endif #ifdef CONFIG_SYSCTL @@ -65,6 +71,144 @@ static struct ctl_table loadpin_sysctl_table[] = { { } }; +#ifdef CONFIG_SECURITY_LOADPIN_VERITY + +static int proc_verity_root_digests(struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) +{ + struct trusted_root_digest *trd; + char *buf; + int rc; + + if (write) { + struct ctl_table tbl = *table; + char *p, *d; + + if (*ppos) + return -EINVAL; + + if (verity_digests_set) + return -EPERM; + + buf = kzalloc(tbl.maxlen, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + tbl.data = buf; + + rc = proc_dostring(&tbl, write, buffer, lenp, ppos); + if (rc) { + kfree(buf); + return rc; + } + + if (strlen(buf) == 0) { + verity_digests_set = true; + return false; + } + + p = buf; + while ((d = strsep(&p, ",")) != NULL) { + int len = strlen(d); + + if (len % 2) { + rc = -EINVAL; + goto err; + } + + len /= 2; + + trd = kzalloc(sizeof(*trd), GFP_KERNEL); + if (!trd) { + rc = -ENOMEM; + goto err; + } + + list_add_tail(&trd->node, &trusted_verity_root_digests); + + trd->data = kzalloc(len, GFP_KERNEL); + if (!trd->data) { + rc = -ENOMEM; + goto err; + } + + if (hex2bin(trd->data, d, len)) { + rc = -EINVAL; + goto err; + } + + trd->len = len; + } + + kfree(buf); + + if (!list_empty(&trusted_verity_root_digests)) { + dm_verity_loadpin_set_trusted_root_digests(&trusted_verity_root_digests); + verity_digests_set = true; + } + } else { + struct ctl_table tbl = { .maxlen = 0 }; + size_t off = 0; + + list_for_each_entry(trd, &trusted_verity_root_digests, node) { + /* two ASCII characters per byte and a comma / '\0' */ + tbl.maxlen += (trd->len * 2) + 1; + } + + tbl.data = kzalloc(tbl.maxlen, GFP_KERNEL); + + list_for_each_entry(trd, &trusted_verity_root_digests, node) { + int i; + + if (off > 0) { + snprintf(tbl.data + off, tbl.maxlen - off, ","); + off++; + } + + for (i = 0; i < trd->len; i++) { + snprintf(tbl.data + off, tbl.maxlen - off, "%02x", trd->data[i]); + off += 2; + } + } + + proc_dostring(&tbl, write, buffer, lenp, ppos); + kfree(tbl.data); + } + + return 0; + +err: + kfree(buf); + + { + struct trusted_root_digest *tmp; + + list_for_each_entry_safe(trd, tmp, &trusted_verity_root_digests, node) { + kfree(trd->data); + list_del(&trd->node); + kfree(trd); + } + } + + return rc; +} + +static struct ctl_table loadpin_sysctl_table_verity[] = { + { + .procname = "trusted_verity_root_digests", + .maxlen = SZ_4K, + .mode = 0644, + .proc_handler = proc_verity_root_digests, + }, + + { } +}; +#else + +static struct ctl_table loadpin_sysctl_table_verity[] = {}; + +#endif /* CONFIG_SECURITY_LOADPIN_VERITY */ + /* * This must be called after early kernel init, since then the rootdev * is available. @@ -118,6 +262,20 @@ 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 +332,8 @@ 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 +399,13 @@ 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)) + pr_notice("sysctl registration failed!\n"); + } + return 0; } -- 2.36.0.rc0.470.gd361397f0d-goog -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel