From patchwork Mon Jun 20 18:43:36 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Emese Revfy X-Patchwork-Id: 9188505 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 229BC6075E for ; Mon, 20 Jun 2016 18:37:11 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 11B9027BE5 for ; Mon, 20 Jun 2016 18:37:11 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 03ED527C2C; Mon, 20 Jun 2016 18:37:11 +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=-4.1 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_MED, T_DKIM_INVALID 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 2E40E27BE5 for ; Mon, 20 Jun 2016 18:37:10 +0000 (UTC) Received: (qmail 27876 invoked by uid 550); 20 Jun 2016 18:37:08 -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: Reply-To: kernel-hardening@lists.openwall.com Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 27858 invoked from network); 20 Jun 2016 18:37:07 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=lYfUlDKCzdUQpSbLKNtP97Y9gE0ATbS+HiOJ9AvSJKQ=; b=C8wLAgdlOyS/k4ZskDjrq3zA1h/pwmmnFsvu61DmBkL6ZWF2Uv8aqanikfDuf24pJu uNmNq3rgNy+ly8NoD36kt3v5t1CRDNz36zKypyNmMvFodkaCDWKFmyk3ZQtI706HG+vB ysKqRpKPWPmlKND87qU1jfZl6Yh3DADiCEY9cLa2YblmcK+w776X2Fo/mZz7XmDheCXM gV1fkuzdNPdPYybYUJBMKr8goosx6B0+9i3UjI3iwWoZRcbs0Xpa/PLNEZPR83iOgXyu iSYWNPvlOyNNpHKe2zk92KsK01mrmd70UAIMrbN30ShsZJsoGVc1/LTC5LZxRXmXxmH/ fRug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=lYfUlDKCzdUQpSbLKNtP97Y9gE0ATbS+HiOJ9AvSJKQ=; b=hVkrogd5MgLNossW5M9/KUR8gGnjfRdRSmrL/VjW1ki1aodMzMPWrrRL1FG/yWLv+o JexhYlDEcMgtS9JGdxWLHSOx0SqdpEY+mi33l2dSUwtyfzK3T3+Aw5Sp3kdECing3ss6 6sgi1C24L9Kca/pQCpWZqBW4VuM1/x8h5xeIfaRIvW/N+THC9Etsj+nLMzLUNehzwOc+ FwKhFd+0Yk5CWJ5t5OVobAY6IY6yQzYMo1VFC0fp0b6b0Ieutevbn/93zvujz65EhEEW +nuLAVVUuFIJRaJozgTbVzeFDaV7JBWaAfXtEOKQJ7SoyLJX4lSS0ExdiDpbvaUEFAcw rkgg== X-Gm-Message-State: ALyK8tIfSimC3De9RgeS9VtUr+TjfSVLAYuru7nnmWuTzWsmAgaR8DlmGLnvj/r4eWgPpg== X-Received: by 10.28.45.142 with SMTP id t136mr658981wmt.40.1466447816515; Mon, 20 Jun 2016 11:36:56 -0700 (PDT) Date: Mon, 20 Jun 2016 20:43:36 +0200 From: Emese Revfy To: kernel-hardening@lists.openwall.com Cc: pageexec@freemail.hu, spender@grsecurity.net, mmarek@suse.com, keescook@chromium.org, linux-kernel@vger.kernel.org, yamada.masahiro@socionext.com, linux-kbuild@vger.kernel.org, tytso@mit.edu, akpm@linux-foundation.org, linux-mm@kvack.org, axboe@kernel.dk, viro@zeniv.linux.org.uk, paulmck@linux.vnet.ibm.com, mingo@redhat.com, tglx@linutronix.de, bart.vanassche@sandisk.com, davem@davemloft.net Message-Id: <20160620204336.9f5ca671b32acf298ab4bc17@gmail.com> In-Reply-To: <20160620203910.a8b6b5b10d18f24661916e7b@gmail.com> References: <20160620203910.a8b6b5b10d18f24661916e7b@gmail.com> X-Mailer: Sylpheed 3.5.0 (GTK+ 2.24.30; x86_64-pc-linux-gnu) Mime-Version: 1.0 Subject: [kernel-hardening] [PATCH v4 4/4] Add the extra_latent_entropy kernel parameter X-Virus-Scanned: ClamAV using ClamSMTP When extra_latent_entropy is passed on the kernel command line, entropy will be extracted from up to the first 4GB of RAM while the runtime memory allocator is being initialized. Based on work created by the PaX Team. Signed-off-by: Emese Revfy --- Documentation/kernel-parameters.txt | 5 +++++ arch/Kconfig | 5 +++++ mm/page_alloc.c | 26 ++++++++++++++++++++++++++ 3 files changed, 36 insertions(+) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 82b42c9..d870702 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2862,6 +2862,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. the specified number of seconds. This is to be used if your oopses keep scrolling off the screen. + extra_latent_entropy + Enable a very simple form of latent entropy extraction + from the first 4GB of memory as the bootmem allocator + passes the memory pages to the buddy allocator. + pcbit= [HW,ISDN] pcd. [PARIDE] diff --git a/arch/Kconfig b/arch/Kconfig index 4b7cc2f..3374d50 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -404,6 +404,11 @@ config GCC_PLUGIN_LATENT_ENTROPY is some slowdown of the boot process (about 0.5%) and fork and irq processing. + When extra_latent_entropy is passed on the kernel command line, + entropy will be extracted from up to the first 4GB of RAM while the + runtime memory allocator is being initialized. This costs even more + slowdown of the boot process. + Note that entropy extracted this way is not cryptographically secure! diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ffc4f4a..0a40c12 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -63,6 +63,7 @@ #include #include #include +#include #include #include @@ -1234,6 +1235,15 @@ static void __free_pages_ok(struct page *page, unsigned int order) local_irq_restore(flags); } +bool __meminitdata extra_latent_entropy; + +static int __init setup_extra_latent_entropy(char *str) +{ + extra_latent_entropy = true; + return 0; +} +early_param("extra_latent_entropy", setup_extra_latent_entropy); + #ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY volatile u64 latent_entropy __latent_entropy; EXPORT_SYMBOL(latent_entropy); @@ -1254,6 +1264,22 @@ static void __init __free_pages_boot_core(struct page *page, unsigned int order) __ClearPageReserved(p); set_page_count(p, 0); + if (extra_latent_entropy && !PageHighMem(page) && + page_to_pfn(page) < 0x100000) { + u64 hash = 0; + size_t index, end = PAGE_SIZE * nr_pages / sizeof(hash); + const u64 *data = lowmem_page_address(page); + + for (index = 0; index < end; index++) + hash ^= hash + data[index]; +#ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY + latent_entropy ^= hash; + add_device_randomness((const void *)&latent_entropy, sizeof(latent_entropy)); +#else + add_device_randomness((const void *)&hash, sizeof(hash)); +#endif + } + page_zone(page)->managed_pages += nr_pages; set_page_refcounted(page); __free_pages(page, order);