From patchwork Mon Feb 11 23:27:49 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Igor Stoppa X-Patchwork-Id: 10807009 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A55761399 for ; Mon, 11 Feb 2019 23:30:41 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 96A2F2AF1A for ; Mon, 11 Feb 2019 23:30:41 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8AA6F2B0AC; Mon, 11 Feb 2019 23:30:41 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.0 required=2.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FROM,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 981542AF1A for ; Mon, 11 Feb 2019 23:30:40 +0000 (UTC) Received: (qmail 1816 invoked by uid 550); 11 Feb 2019 23:28:56 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 1741 invoked from network); 11 Feb 2019 23:28:55 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references:reply-to :mime-version:content-transfer-encoding; bh=VlNzKepo585QEAzr1PoW4dWwLybStReaiWjN7bcxj8g=; b=BI2AisEr9GW64YlypsEsgzISrsfXnzkEjXKfspuUjubyPjQUZeYyTJsNWfamyXpj28 CgpAScsAf8IZ1P4wcgWzrKhfDOZpJKvDiiSA1Gv0AKtGLp9Pr7+QJvlRkwrHQydw9YXJ ras/v8CRf+ug8I2VtFx/txAEkoyDb2GFIydZ3Z70vOkH6vXAgc7rcUYlKmbRJDUojLE6 EPEbI25rqik5A1usnzwzAAmQfHxjH/Rhl6eR8jA4jOBebaR4/w8+alWM05wleyXmZdc4 ENHs8fK+3TEpKW3p/CyPVjpuBNdt/+LnYDPo5TCRizbKgOHwgwBB6g4/ozhOWVUJc6am cN3g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:reply-to:mime-version:content-transfer-encoding; bh=VlNzKepo585QEAzr1PoW4dWwLybStReaiWjN7bcxj8g=; b=qQTphNEfnf0bffpE+6kTlQflETI8zBCpPfp/AnvVNZ7oMyprfJfnv7QcQenktdZ0Be 0npoUl/EQuUhpWuV1SExJol6Bx+uqCIYe7W8SItQ76WqkltpZzAa7dlcaSuud16gNIkE J8FmpPHvheu2cgKcW68/C2xSuBOgI8NnfzXhbbcQRccEetYvwuFBTVMPPeq0IxaeOBgs PuUvInJil1LwiWKFHN1XTeo92/zD8tzcoJVNTZuqn7Ind/1uyKbACQVevaUPeYvumbLq OphPCOyKdUwnrzk3LXrYiKEihRYVM5DoYh1dMFHE7yqZqEToiqHrAeYQMQfV7P0whc55 Ohqg== X-Gm-Message-State: AHQUAubtD7wbfssxM+8nbKwj9CH+wMs87KtL9trBIfmofqU1124UX9Vg FUBX5QaKrKrn9hUXrMGc5ns= X-Google-Smtp-Source: AHgI3IYAStsHXTbFOi9toTUJa7sYc2xWbjGcnPdHeaXJGeDxn/CbffDpZEeCBK0xVjj3LAdOW97ZlA== X-Received: by 2002:a1c:f707:: with SMTP id v7mr528939wmh.18.1549927724197; Mon, 11 Feb 2019 15:28:44 -0800 (PST) From: Igor Stoppa X-Google-Original-From: Igor Stoppa To: Cc: Igor Stoppa , Andy Lutomirski , Nadav Amit , Matthew Wilcox , Peter Zijlstra , Kees Cook , Dave Hansen , Mimi Zohar , Thiago Jung Bauermann , Ahmed Soliman , linux-integrity@vger.kernel.org, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH v4 12/12] IMA: turn ima_policy_flags into __wr_after_init Date: Tue, 12 Feb 2019 01:27:49 +0200 Message-Id: <93a44c8854b914fb9558fd37b7c4c9ee6051c20c.1549927666.git.igor.stoppa@huawei.com> X-Mailer: git-send-email 2.19.1 In-Reply-To: References: MIME-Version: 1.0 X-Virus-Scanned: ClamAV using ClamSMTP The policy flags could be targeted by an attacker aiming at disabling IMA, so that there would be no trace of a file system modification in the measurement list. Since the flags can be altered at runtime, it is not possible to make them become fully read-only, for example with __ro_after_init. __wr_after_init can still provide some protection, at least against simple memory overwrite attacks Signed-off-by: Igor Stoppa CC: Andy Lutomirski CC: Nadav Amit CC: Matthew Wilcox CC: Peter Zijlstra CC: Kees Cook CC: Dave Hansen CC: Mimi Zohar CC: Thiago Jung Bauermann CC: Ahmed Soliman CC: linux-integrity@vger.kernel.org CC: kernel-hardening@lists.openwall.com CC: linux-mm@kvack.org CC: linux-kernel@vger.kernel.org --- security/integrity/ima/ima.h | 3 ++- security/integrity/ima/ima_policy.c | 9 +++++---- 2 files changed, 7 insertions(+), 5 deletions(-) diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index cc12f3449a72..297c25f5122e 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -24,6 +24,7 @@ #include #include #include +#include #include #include "../integrity.h" @@ -50,7 +51,7 @@ enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8 }; #define IMA_TEMPLATE_IMA_FMT "d|n" /* current content of the policy */ -extern int ima_policy_flag; +extern int ima_policy_flag __wr_after_init; /* set during initialization */ extern int ima_hash_algo; diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 8bc8a1c8cb3f..d49c545b9cfb 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -48,7 +48,7 @@ #define INVALID_PCR(a) (((a) < 0) || \ (a) >= (FIELD_SIZEOF(struct integrity_iint_cache, measured_pcrs) * 8)) -int ima_policy_flag; +int ima_policy_flag __wr_after_init; static int temp_ima_appraise; static int build_ima_appraise __ro_after_init; @@ -460,12 +460,13 @@ void ima_update_policy_flag(void) list_for_each_entry(entry, ima_rules, list) { if (entry->action & IMA_DO_MASK) - ima_policy_flag |= entry->action; + wr_assign(ima_policy_flag, + ima_policy_flag | entry->action); } ima_appraise |= (build_ima_appraise | temp_ima_appraise); if (!ima_appraise) - ima_policy_flag &= ~IMA_APPRAISE; + wr_assign(ima_policy_flag, ima_policy_flag & ~IMA_APPRAISE); } static int ima_appraise_flag(enum ima_hooks func) @@ -651,7 +652,7 @@ void ima_update_policy(void) list_splice_tail_init_rcu(&ima_temp_rules, policy, synchronize_rcu); if (ima_rules != policy) { - ima_policy_flag = 0; + wr_assign(ima_policy_flag, 0); ima_rules = policy; /*