From patchwork Wed May 23 19:54:15 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Garnier X-Patchwork-Id: 10422295 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 1E05B60224 for ; Wed, 23 May 2018 20:00:27 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0C781291CE for ; Wed, 23 May 2018 20:00:27 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id F4143291D8; Wed, 23 May 2018 20:00:26 +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=-12.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED, USER_IN_DEF_DKIM_WL 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 D37BF291CE for ; Wed, 23 May 2018 20:00:25 +0000 (UTC) Received: (qmail 24449 invoked by uid 550); 23 May 2018 19:56:16 -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 24308 invoked from network); 23 May 2018 19:56:09 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=pEseXgr7lOEb5LFKhPM2MSdChPttkJotuOcJfjI4qAw=; b=XyQWYEfwZ+ee8GzLV1Tccka/lOchqDFaVyOKTBwIxS2r6Ea36kwSjx87sDCZMQIqYr e2TCBmK3eG0zAIKgRtdl/NnRP+xzeugKzTv9dcaqkibPgW1iazeqqnYjy8uCM4FJbvkM i4CzGmpEjugpuoDc6nHK09tT3M1u76yr6ruAhOvK1pi1FCXvTVkKGxP7epRfbGAEJFw1 cYCKfScJ5hvnFhFKZdmqTkpgrS4l9/xlty1drzls6OUUTQnugg2pv1D+g8NHFW1CfSkO 0voy04b4R1PvBy3PyeibQHFv/NYwZSLvlZomXzBig/qCstuZYc/HLz9T5kYpe0TqdlcG mb0A== 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; bh=pEseXgr7lOEb5LFKhPM2MSdChPttkJotuOcJfjI4qAw=; b=B/jGy0iOdl7cRhtucuIwZa7hzdodeUucsNvE5mMFbmyz2wVrK4V7P66aUyBWMUlbPv IFFFS3AnyZ6r/2uITQqhmS4FE9DH3xr/qXpTqyLXSLc4i5vQoEcBknwswbaifhs6xT9V 3GbDrFKyT5WUzY2G55h405c3psQyonk6oDvtBLiCIs5L2FMjvfv5n8/L3ViuLe5xElc9 mXJl+PSkfcP+b3D1P4JpUItujNsX94A2W2kR2yJda0M7ThLwiJdRTdqpIoh3wKECyrqM JYVcWOREnFeFpSYGmt78aCBQp8n+HoQMHj2AJUHl3K1S1grgcNqqzLhX1D5Z4qSJzfzf kkoA== X-Gm-Message-State: ALKqPwdUCuC8FwlEEIbfPShvJ5cnjpuLXNNhh+ih7aB9qg4q3zKo/H2P ZWqc73iKWv6EtfLhZSbVTGcNOg== X-Google-Smtp-Source: AB8JxZpp8rTobJmGQLmO8R1n+vcYg55kcUnRRL2JB112UXyjBF0CStpZG8UV8rzs/T6O37GDc+rZhQ== X-Received: by 2002:a17:902:2f43:: with SMTP id s61-v6mr4142988plb.99.1527105356731; Wed, 23 May 2018 12:55:56 -0700 (PDT) From: Thomas Garnier To: Herbert Xu , "David S . Miller" , Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , Peter Zijlstra , Josh Poimboeuf , Greg Kroah-Hartman , Thomas Garnier , Philippe Ombredanne , Kate Stewart , Arnaldo Carvalho de Melo , Yonghong Song , Andrey Ryabinin , Kees Cook , Tom Lendacky , "Kirill A . Shutemov" , Andy Lutomirski , Dominik Brodowski , Borislav Petkov , Borislav Petkov , "Rafael J . Wysocki" , Len Brown , Pavel Machek , Juergen Gross , Alok Kataria , Steven Rostedt , Jan Kiszka , Tejun Heo , Christoph Lameter , Dennis Zhou , Boris Ostrovsky , Alexey Dobriyan , Masami Hiramatsu , Cao jin , Francis Deslauriers , "Paul E . McKenney" , Nicolas Pitre , Andrew Morton , Randy Dunlap , "Luis R . Rodriguez" , Arnd Bergmann , Christopher Li , Jason Baron , Mika Westerberg , Lukas Wunner , Dou Liyang , Sergey Senozhatsky , Petr Mladek , Masahiro Yamada , Ingo Molnar , Nicholas Piggin , "H . J . Lu" , Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Joerg Roedel , David Woodhouse , Dave Hansen , Rik van Riel , Jia Zhang , Ricardo Neri , Jonathan Corbet , Jan Beulich , Matthias Kaehlcke , Baoquan He , =?UTF-8?q?Jan=20H=20=2E=20Sch=C3=B6nherr?= , Daniel Micay Cc: x86@kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, virtualization@lists.linux-foundation.org, xen-devel@lists.xenproject.org, linux-arch@vger.kernel.org, linux-sparse@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, kernel-hardening@lists.openwall.com Subject: [PATCH v3 21/27] x86/ftrace: Adapt function tracing for PIE support Date: Wed, 23 May 2018 12:54:15 -0700 Message-Id: <20180523195421.180248-22-thgarnie@google.com> X-Mailer: git-send-email 2.17.0.441.gb46fe60e1d-goog In-Reply-To: <20180523195421.180248-1-thgarnie@google.com> References: <20180523195421.180248-1-thgarnie@google.com> X-Virus-Scanned: ClamAV using ClamSMTP When using -fPIE/PIC with function tracing, the compiler generates a call through the GOT (call *__fentry__@GOTPCREL). This instruction takes 6 bytes instead of 5 on the usual relative call. If PIE is enabled, replace the 6th byte of the GOT call by a 1-byte nop so ftrace can handle the previous 5-bytes as before. Position Independent Executable (PIE) support will allow to extended the KASLR randomization range below the -2G memory limit. Signed-off-by: Thomas Garnier --- arch/x86/include/asm/ftrace.h | 6 +++-- arch/x86/include/asm/sections.h | 4 ++++ arch/x86/kernel/ftrace.c | 42 +++++++++++++++++++++++++++++++-- 3 files changed, 48 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h index c18ed65287d5..8f2decce38d8 100644 --- a/arch/x86/include/asm/ftrace.h +++ b/arch/x86/include/asm/ftrace.h @@ -25,9 +25,11 @@ extern void __fentry__(void); static inline unsigned long ftrace_call_adjust(unsigned long addr) { /* - * addr is the address of the mcount call instruction. - * recordmcount does the necessary offset calculation. + * addr is the address of the mcount call instruction. PIE has always a + * byte added to the start of the function. */ + if (IS_ENABLED(CONFIG_X86_PIE)) + addr -= 1; return addr; } diff --git a/arch/x86/include/asm/sections.h b/arch/x86/include/asm/sections.h index 5c019d23d06b..da3d98bb2bcb 100644 --- a/arch/x86/include/asm/sections.h +++ b/arch/x86/include/asm/sections.h @@ -13,4 +13,8 @@ extern char __end_rodata_hpage_align[]; extern char __entry_trampoline_start[], __entry_trampoline_end[]; #endif +#if defined(CONFIG_X86_PIE) +extern char __start_got[], __end_got[]; +#endif + #endif /* _ASM_X86_SECTIONS_H */ diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index 01ebcb6f263e..73b3c30cb7a3 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -102,7 +102,7 @@ static const unsigned char *ftrace_nop_replace(void) static int ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code, - unsigned const char *new_code) + unsigned const char *new_code) { unsigned char replaced[MCOUNT_INSN_SIZE]; @@ -135,6 +135,44 @@ ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code, return 0; } +/* Bytes before call GOT offset */ +const unsigned char got_call_preinsn[] = { 0xff, 0x15 }; + +static int +ftrace_modify_initial_code(unsigned long ip, unsigned const char *old_code, + unsigned const char *new_code) +{ + unsigned char replaced[MCOUNT_INSN_SIZE + 1]; + + ftrace_expected = old_code; + + /* + * If PIE is not enabled or no GOT call was found, default to the + * original approach to code modification. + */ + if (!IS_ENABLED(CONFIG_X86_PIE) || + probe_kernel_read(replaced, (void *)ip, sizeof(replaced)) || + memcmp(replaced, got_call_preinsn, sizeof(got_call_preinsn))) + return ftrace_modify_code_direct(ip, old_code, new_code); + + /* + * Build a nop slide with a 5-byte nop and 1-byte nop to keep the ftrace + * hooking algorithm working with the expected 5 bytes instruction. + */ + memcpy(replaced, new_code, MCOUNT_INSN_SIZE); + replaced[MCOUNT_INSN_SIZE] = ideal_nops[1][0]; + + ip = text_ip_addr(ip); + + if (probe_kernel_write((void *)ip, replaced, sizeof(replaced))) + return -EPERM; + + sync_core(); + + return 0; + +} + int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) { @@ -153,7 +191,7 @@ int ftrace_make_nop(struct module *mod, * just modify the code directly. */ if (addr == MCOUNT_ADDR) - return ftrace_modify_code_direct(rec->ip, old, new); + return ftrace_modify_initial_code(rec->ip, old, new); ftrace_expected = NULL;