From patchwork Thu Jan 6 23:43:13 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aaron Tomlin X-Patchwork-Id: 12705915 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 B7080C433EF for ; Thu, 6 Jan 2022 23:43:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245729AbiAFXng (ORCPT ); Thu, 6 Jan 2022 18:43:36 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:26916 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245727AbiAFXnc (ORCPT ); Thu, 6 Jan 2022 18:43:32 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1641512610; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=mCGQaji14i2F94mV0DWpkRKJAs6KEBhnNJRRFLq3kec=; b=OUIPloov7DBXVoL0wecHN3PdmhFI1qvwVakZ/Q3B3JDwqHElxMHbwUmMZaOkjHRT7bfWGO EEHAAQ4FxaYbk1GTmzBZb46vVbs+bo9ZXAI/rXTC3+jSPKJTHyn+KqSWHQT2VH1zGVxv9a KhBHSSp9Wtv3cjTG0EKP94sS4exejOc= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-581-ND9HUTcKN5uwVv0TDb1gwg-1; Thu, 06 Jan 2022 18:43:29 -0500 X-MC-Unique: ND9HUTcKN5uwVv0TDb1gwg-1 Received: by mail-wm1-f70.google.com with SMTP id l34-20020a05600c08a200b003478e251a32so75642wmp.0 for ; Thu, 06 Jan 2022 15:43:29 -0800 (PST) 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=mCGQaji14i2F94mV0DWpkRKJAs6KEBhnNJRRFLq3kec=; b=ox3lHNDziBB/nVJq7oVolBPbVO2WMI5V/fg2TWXxnyMuchUKV0zrMdw01mo23MoVuK BDkI0aLl4Y+Qig185wc52Jq3OdkIgzBrGy2A56kJ2GvcFaTqHhWxMwl7I4fcGzblF00l gu4oQFo/z29ULH7YuyJpnJo1xLF01IYPTA6magzysSv0dvyPxyjc8TYa80hTXbd3MxPR gSUOnO+RtZ0Ny8ct+CUXPxJBMEOgAuG3njzcZcfrXIKu9rMPq3lmhi/U6PwDBwdigmd+ vybZ4TtO0bH1DEhxkB4+FmaJMxcfayjnNn1NDENFRy00JlU5mQpgjoXB2qrZiyjQwNbU mpbQ== X-Gm-Message-State: AOAM5304FKc7W4aIy+6o9G+BUIoGXpyHJPLkkgGbqs1ftAwjabsDEo85 HwIfJCJxz0lkO207TzLnumK3FCairfLdLk0SeWZ18w2GBekOE3CPx8WRbXLUdfLjxZsa+tIM3z5 zGzpFRlpJCiR+nrahbq9Ld9ai X-Received: by 2002:a5d:6f11:: with SMTP id ay17mr14858185wrb.662.1641512608277; Thu, 06 Jan 2022 15:43:28 -0800 (PST) X-Google-Smtp-Source: ABdhPJzA4y/2KQTMM+c6WywYryhpbnWsxkIUVDdI6DSoEVL948RrCr73yqG7vfM3NoMTgwDbY/bJ5w== X-Received: by 2002:a5d:6f11:: with SMTP id ay17mr14858171wrb.662.1641512608103; Thu, 06 Jan 2022 15:43:28 -0800 (PST) Received: from localhost (cpc111743-lutn13-2-0-cust979.9-3.cable.virginm.net. [82.17.115.212]) by smtp.gmail.com with ESMTPSA id g5sm3761050wrd.100.2022.01.06.15.43.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Jan 2022 15:43:27 -0800 (PST) From: Aaron Tomlin To: mcgrof@kernel.org Cc: cl@linux.com, pmladek@suse.com, mbenes@suse.cz, akpm@linux-foundation.org, jeyu@kernel.org, linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org, atomlin@atomlin.com, ghalat@redhat.com, allen.lkml@gmail.com Subject: [RFC PATCH v2 07/13] module: Move extra signature support out of core code Date: Thu, 6 Jan 2022 23:43:13 +0000 Message-Id: <20220106234319.2067842-8-atomlin@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220106234319.2067842-1-atomlin@redhat.com> References: <20220106234319.2067842-1-atomlin@redhat.com> MIME-Version: 1.0 Precedence: bulk List-ID: No functional change. This patch migrates additional module signature check code from core module code into kernel/module/signing.c. Signed-off-by: Aaron Tomlin --- include/linux/module.h | 5 ++- kernel/module/internal.h | 9 +++++ kernel/module/main.c | 86 ---------------------------------------- kernel/module/signing.c | 75 +++++++++++++++++++++++++++++++++++ 4 files changed, 87 insertions(+), 88 deletions(-) diff --git a/include/linux/module.h b/include/linux/module.h index 218ac6768433..3383912268af 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -736,8 +736,8 @@ static inline bool is_livepatch_module(struct module *mod) } #endif /* CONFIG_LIVEPATCH */ -bool is_module_sig_enforced(void); -void set_module_sig_enforced(void); +extern bool is_module_sig_enforced(void); +extern void set_module_sig_enforced(void); #else /* !CONFIG_MODULES... */ @@ -927,6 +927,7 @@ static inline bool module_sig_ok(struct module *module) { return true; } +#define sig_enforce false #endif /* CONFIG_MODULE_SIG */ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, diff --git a/kernel/module/internal.h b/kernel/module/internal.h index 91ef152aeffb..b4db57bafcd3 100644 --- a/kernel/module/internal.h +++ b/kernel/module/internal.h @@ -63,3 +63,12 @@ static inline int copy_module_elf(struct module *mod, struct load_info *info) } static inline void free_module_elf(struct module *mod) { } #endif /* CONFIG_LIVEPATCH */ + +#ifdef CONFIG_MODULE_SIG +extern int module_sig_check(struct load_info *info, int flags); +#else /* !CONFIG_MODULE_SIG */ +static int module_sig_check(struct load_info *info, int flags) +{ + return 0; +} +#endif /* !CONFIG_MODULE_SIG */ diff --git a/kernel/module/main.c b/kernel/module/main.c index c404d00f7958..8f8a904d5ba7 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -22,7 +22,6 @@ #include #include #include -#include #include #include #include @@ -114,28 +113,6 @@ static void module_assert_mutex_or_preempt(void) #endif } -#ifdef CONFIG_MODULE_SIG -static bool sig_enforce = IS_ENABLED(CONFIG_MODULE_SIG_FORCE); -module_param(sig_enforce, bool_enable_only, 0644); - -void set_module_sig_enforced(void) -{ - sig_enforce = true; -} -#else -#define sig_enforce false -#endif - -/* - * Export sig_enforce kernel cmdline parameter to allow other subsystems rely - * on that instead of directly to CONFIG_MODULE_SIG_FORCE config. - */ -bool is_module_sig_enforced(void) -{ - return sig_enforce; -} -EXPORT_SYMBOL(is_module_sig_enforced); - /* Block module loading/unloading? */ int modules_disabled = 0; core_param(nomodule, modules_disabled, bint, 0); @@ -2517,69 +2494,6 @@ static inline void kmemleak_load_module(const struct module *mod, } #endif -#ifdef CONFIG_MODULE_SIG -static int module_sig_check(struct load_info *info, int flags) -{ - int err = -ENODATA; - const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; - const char *reason; - const void *mod = info->hdr; - - /* - * Require flags == 0, as a module with version information - * removed is no longer the module that was signed - */ - if (flags == 0 && - info->len > markerlen && - memcmp(mod + info->len - markerlen, MODULE_SIG_STRING, markerlen) == 0) { - /* We truncate the module to discard the signature */ - info->len -= markerlen; - err = mod_verify_sig(mod, info); - if (!err) { - info->sig_ok = true; - return 0; - } - } - - /* - * We don't permit modules to be loaded into the trusted kernels - * without a valid signature on them, but if we're not enforcing, - * certain errors are non-fatal. - */ - switch (err) { - case -ENODATA: - reason = "unsigned module"; - break; - case -ENOPKG: - reason = "module with unsupported crypto"; - break; - case -ENOKEY: - reason = "module with unavailable key"; - break; - - default: - /* - * All other errors are fatal, including lack of memory, - * unparseable signatures, and signature check failures -- - * even if signatures aren't required. - */ - return err; - } - - if (is_module_sig_enforced()) { - pr_notice("Loading of %s is rejected\n", reason); - return -EKEYREJECTED; - } - - return security_locked_down(LOCKDOWN_MODULE_SIGNATURE); -} -#else /* !CONFIG_MODULE_SIG */ -static int module_sig_check(struct load_info *info, int flags) -{ - return 0; -} -#endif /* !CONFIG_MODULE_SIG */ - static int validate_section_offset(struct load_info *info, Elf_Shdr *shdr) { unsigned long secend; diff --git a/kernel/module/signing.c b/kernel/module/signing.c index 8aeb6d2ee94b..ff41541e982a 100644 --- a/kernel/module/signing.c +++ b/kernel/module/signing.c @@ -11,9 +11,28 @@ #include #include #include +#include #include #include "internal.h" +static bool sig_enforce = IS_ENABLED(CONFIG_MODULE_SIG_FORCE); +module_param(sig_enforce, bool_enable_only, 0644); + +/* + * Export sig_enforce kernel cmdline parameter to allow other subsystems rely + * on that instead of directly to CONFIG_MODULE_SIG_FORCE config. + */ +bool is_module_sig_enforced(void) +{ + return sig_enforce; +} +EXPORT_SYMBOL(is_module_sig_enforced); + +void set_module_sig_enforced(void) +{ + sig_enforce = true; +} + /* * Verify the signature on a module. */ @@ -43,3 +62,59 @@ int mod_verify_sig(const void *mod, struct load_info *info) VERIFYING_MODULE_SIGNATURE, NULL, NULL); } + +int module_sig_check(struct load_info *info, int flags) +{ + int err = -ENODATA; + const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; + const char *reason; + const void *mod = info->hdr; + + /* + * Require flags == 0, as a module with version information + * removed is no longer the module that was signed + */ + if (flags == 0 && + info->len > markerlen && + memcmp(mod + info->len - markerlen, MODULE_SIG_STRING, markerlen) == 0) { + /* We truncate the module to discard the signature */ + info->len -= markerlen; + err = mod_verify_sig(mod, info); + if (!err) { + info->sig_ok = true; + return 0; + } + } + + /* + * We don't permit modules to be loaded into the trusted kernels + * without a valid signature on them, but if we're not enforcing, + * certain errors are non-fatal. + */ + switch (err) { + case -ENODATA: + reason = "unsigned module"; + break; + case -ENOPKG: + reason = "module with unsupported crypto"; + break; + case -ENOKEY: + reason = "module with unavailable key"; + break; + + default: + /* + * All other errors are fatal, including lack of memory, + * unparseable signatures, and signature check failures -- + * even if signatures aren't required. + */ + return err; + } + + if (is_module_sig_enforced()) { + pr_notice("Loading of %s is rejected\n", reason); + return -EKEYREJECTED; + } + + return security_locked_down(LOCKDOWN_MODULE_SIGNATURE); +}