From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?B?dGlwLWJvdCBmb3IgS2VlcyBDb29rIDx0aXBib3RAenl0b3IuY29tPg==?=@zytor.com Subject: =?UTF-8?B?W3RpcDptbS9yZWFkb25seV0gbGtkdG06IFZlcmlmeSB0aGF0ICdfX3JvX2FmdGU=?= =?UTF-8?B?cl9pbml0JyB3b3JrcyBjb3JyZWN0bHk=?= Date: Mon, 22 Feb 2016 04:19:57 -0800 Message-ID: References: <1455748879-21872-6-git-send-email-keescook@chromium.org> Reply-To: minipli@googlemail.com, linux-arch@vger.kernel.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, bp@alien8.de, brgerst@gmail.com, peterz@infradead.org, mingo@kernel.org, dvlasenk@redhat.com, tglx@linutronix.de, arnd@arndb.de, david.brown@linaro.org, luto@amacapital.net, pageexec@freemail.hu, keescook@chromium.org, re.emese@gmail.com, mpe@ellerman.id.au, hpa@zytor.com Mime-Version: =?UTF-8?B?MS4w?= Content-Type: =?UTF-8?B?dGV4dC9wbGFpbjsgY2hhcnNldD1VVEYtOA==?= Content-Transfer-Encoding: =?UTF-8?B?OGJpdA==?= Return-path: In-Reply-To: <1455748879-21872-6-git-send-email-keescook@chromium.org> Content-Disposition: =?UTF-8?B?aW5saW5l?= Sender: linux-kernel-owner@vger.kernel.org To: =?UTF-8?B?bGludXgtdGlwLWNvbW1pdHNAdmdlci5rZXJuZWwub3Jn?=@zytor.com Cc: linux-kernel@vger.kernel.org, brgerst@gmail.com, bp@alien8.de, peterz@infradead.org, mingo@kernel.org, dvlasenk@redhat.com, minipli@googlemail.com, linux-arch@vger.kernel.org, torvalds@linux-foundation.org, mpe@ellerman.id.au, hpa@zytor.com, tglx@linutronix.de, arnd@arndb.de, david.brown@linaro.org, luto@amacapital.net, pageexec@freemail.hu, keescook@chromium.org, re.emese@gmail.com List-Id: linux-arch.vger.kernel.org Commit-ID: 7cca071ccbd2a293ea69168ace6abbcdce53098e Gitweb: http://git.kernel.org/tip/7cca071ccbd2a293ea69168ace6abbcdce53098e Author: Kees Cook AuthorDate: Wed, 17 Feb 2016 14:41:16 -0800 Committer: Ingo Molnar CommitDate: Mon, 22 Feb 2016 08:51:38 +0100 lkdtm: Verify that '__ro_after_init' works correctly The new __ro_after_init section should be writable before init, but not after. Validate that it gets updated at init and can't be written to afterwards. Signed-off-by: Kees Cook Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Brian Gerst Cc: David Brown Cc: Denys Vlasenko Cc: Emese Revfy Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Mathias Krause Cc: Michael Ellerman Cc: PaX Team Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: kernel-hardening@lists.openwall.com Cc: linux-arch Link: http://lkml.kernel.org/r/1455748879-21872-6-git-send-email-keescook@chromium.org Signed-off-by: Ingo Molnar --- drivers/misc/lkdtm.c | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) diff --git a/drivers/misc/lkdtm.c b/drivers/misc/lkdtm.c index 11fdadc..2a6eaf1 100644 --- a/drivers/misc/lkdtm.c +++ b/drivers/misc/lkdtm.c @@ -103,6 +103,7 @@ enum ctype { CT_EXEC_USERSPACE, CT_ACCESS_USERSPACE, CT_WRITE_RO, + CT_WRITE_RO_AFTER_INIT, CT_WRITE_KERN, }; @@ -140,6 +141,7 @@ static char* cp_type[] = { "EXEC_USERSPACE", "ACCESS_USERSPACE", "WRITE_RO", + "WRITE_RO_AFTER_INIT", "WRITE_KERN", }; @@ -162,6 +164,7 @@ static DEFINE_SPINLOCK(lock_me_up); static u8 data_area[EXEC_SIZE]; static const unsigned long rodata = 0xAA55AA55; +static unsigned long ro_after_init __ro_after_init = 0x55AA5500; module_param(recur_count, int, 0644); MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test"); @@ -503,11 +506,28 @@ static void lkdtm_do_action(enum ctype which) break; } case CT_WRITE_RO: { - unsigned long *ptr; + /* Explicitly cast away "const" for the test. */ + unsigned long *ptr = (unsigned long *)&rodata; - ptr = (unsigned long *)&rodata; + pr_info("attempting bad rodata write at %p\n", ptr); + *ptr ^= 0xabcd1234; - pr_info("attempting bad write at %p\n", ptr); + break; + } + case CT_WRITE_RO_AFTER_INIT: { + unsigned long *ptr = &ro_after_init; + + /* + * Verify we were written to during init. Since an Oops + * is considered a "success", a failure is to just skip the + * real test. + */ + if ((*ptr & 0xAA) != 0xAA) { + pr_info("%p was NOT written during init!?\n", ptr); + break; + } + + pr_info("attempting bad ro_after_init write at %p\n", ptr); *ptr ^= 0xabcd1234; break; @@ -817,6 +837,9 @@ static int __init lkdtm_module_init(void) int n_debugfs_entries = 1; /* Assume only the direct entry */ int i; + /* Make sure we can write to __ro_after_init values during __init */ + ro_after_init |= 0xAA; + /* Register debugfs interface */ lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL); if (!lkdtm_debugfs_root) { From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from terminus.zytor.com ([198.137.202.10]:58222 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932730AbcBWJKM (ORCPT ); Tue, 23 Feb 2016 04:10:12 -0500 Date: Mon, 22 Feb 2016 04:19:57 -0800 From: =?UTF-8?B?dGlwLWJvdCBmb3IgS2VlcyBDb29rIDx0aXBib3RAenl0b3IuY29tPg==?=@zytor.com Message-ID: Reply-To: minipli@googlemail.com, linux-arch@vger.kernel.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, bp@alien8.de, brgerst@gmail.com, peterz@infradead.org, mingo@kernel.org, dvlasenk@redhat.com, tglx@linutronix.de, arnd@arndb.de, david.brown@linaro.org, luto@amacapital.net, pageexec@freemail.hu, keescook@chromium.org, re.emese@gmail.com, mpe@ellerman.id.au, hpa@zytor.com In-Reply-To: <1455748879-21872-6-git-send-email-keescook@chromium.org> References: <1455748879-21872-6-git-send-email-keescook@chromium.org> Subject: =?UTF-8?B?W3RpcDptbS9yZWFkb25seV0gbGtkdG06IFZlcmlmeSB0aGF0ICdfX3JvX2FmdGU=?= =?UTF-8?B?cl9pbml0JyB3b3JrcyBjb3JyZWN0bHk=?= MIME-Version: =?UTF-8?B?MS4w?= Content-Transfer-Encoding: =?UTF-8?B?OGJpdA==?= Content-Type: =?UTF-8?B?dGV4dC9wbGFpbjsgY2hhcnNldD1VVEYtOA==?= Content-Disposition: =?UTF-8?B?aW5saW5l?= Sender: linux-arch-owner@vger.kernel.org List-ID: To: =?UTF-8?B?bGludXgtdGlwLWNvbW1pdHNAdmdlci5rZXJuZWwub3Jn?=@zytor.com Cc: linux-kernel@vger.kernel.org, brgerst@gmail.com, bp@alien8.de, peterz@infradead.org, mingo@kernel.org, dvlasenk@redhat.com, minipli@googlemail.com, linux-arch@vger.kernel.org, torvalds@linux-foundation.org, mpe@ellerman.id.au, hpa@zytor.com, tglx@linutronix.de, arnd@arndb.de, david.brown@linaro.org, luto@amacapital.net, pageexec@freemail.hu, keescook@chromium.org, re.emese@gmail.com Message-ID: <20160222121957.rU7f8YFVOu9pQ7-TcLfmFBnx-o_392P-w7ilIHRVLog@z> Commit-ID: 7cca071ccbd2a293ea69168ace6abbcdce53098e Gitweb: http://git.kernel.org/tip/7cca071ccbd2a293ea69168ace6abbcdce53098e Author: Kees Cook AuthorDate: Wed, 17 Feb 2016 14:41:16 -0800 Committer: Ingo Molnar CommitDate: Mon, 22 Feb 2016 08:51:38 +0100 lkdtm: Verify that '__ro_after_init' works correctly The new __ro_after_init section should be writable before init, but not after. Validate that it gets updated at init and can't be written to afterwards. Signed-off-by: Kees Cook Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Brian Gerst Cc: David Brown Cc: Denys Vlasenko Cc: Emese Revfy Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Mathias Krause Cc: Michael Ellerman Cc: PaX Team Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: kernel-hardening@lists.openwall.com Cc: linux-arch Link: http://lkml.kernel.org/r/1455748879-21872-6-git-send-email-keescook@chromium.org Signed-off-by: Ingo Molnar --- drivers/misc/lkdtm.c | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) diff --git a/drivers/misc/lkdtm.c b/drivers/misc/lkdtm.c index 11fdadc..2a6eaf1 100644 --- a/drivers/misc/lkdtm.c +++ b/drivers/misc/lkdtm.c @@ -103,6 +103,7 @@ enum ctype { CT_EXEC_USERSPACE, CT_ACCESS_USERSPACE, CT_WRITE_RO, + CT_WRITE_RO_AFTER_INIT, CT_WRITE_KERN, }; @@ -140,6 +141,7 @@ static char* cp_type[] = { "EXEC_USERSPACE", "ACCESS_USERSPACE", "WRITE_RO", + "WRITE_RO_AFTER_INIT", "WRITE_KERN", }; @@ -162,6 +164,7 @@ static DEFINE_SPINLOCK(lock_me_up); static u8 data_area[EXEC_SIZE]; static const unsigned long rodata = 0xAA55AA55; +static unsigned long ro_after_init __ro_after_init = 0x55AA5500; module_param(recur_count, int, 0644); MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test"); @@ -503,11 +506,28 @@ static void lkdtm_do_action(enum ctype which) break; } case CT_WRITE_RO: { - unsigned long *ptr; + /* Explicitly cast away "const" for the test. */ + unsigned long *ptr = (unsigned long *)&rodata; - ptr = (unsigned long *)&rodata; + pr_info("attempting bad rodata write at %p\n", ptr); + *ptr ^= 0xabcd1234; - pr_info("attempting bad write at %p\n", ptr); + break; + } + case CT_WRITE_RO_AFTER_INIT: { + unsigned long *ptr = &ro_after_init; + + /* + * Verify we were written to during init. Since an Oops + * is considered a "success", a failure is to just skip the + * real test. + */ + if ((*ptr & 0xAA) != 0xAA) { + pr_info("%p was NOT written during init!?\n", ptr); + break; + } + + pr_info("attempting bad ro_after_init write at %p\n", ptr); *ptr ^= 0xabcd1234; break; @@ -817,6 +837,9 @@ static int __init lkdtm_module_init(void) int n_debugfs_entries = 1; /* Assume only the direct entry */ int i; + /* Make sure we can write to __ro_after_init values during __init */ + ro_after_init |= 0xAA; + /* Register debugfs interface */ lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL); if (!lkdtm_debugfs_root) {