From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?B?dGlwLWJvdCBmb3IgS2VlcyBDb29rIDx0aXBib3RAenl0b3IuY29tPg==?=@zytor.com Subject: =?UTF-8?B?W3RpcDptbS9yZWFkb25seV0gbW0vaW5pdDogQWRkICdyb2RhdGE9b2ZmJyBib28=?= =?UTF-8?B?dCBjbWRsaW5lIHBhcmFtZXRlciB0byBkaXNhYmxlIHJlYWQtb25seSBrZXJuZWw=?= =?UTF-8?B?IG1hcHBpbmdz?= Date: Mon, 22 Feb 2016 04:18:45 -0800 Message-ID: References: <1455748879-21872-3-git-send-email-keescook@chromium.org> Reply-To: arnd@arndb.de, david.brown@linaro.org, linux-arch@vger.kernel.org, torvalds@linux-foundation.org, keescook@chromium.org, bp@alien8.de, mpe@ellerman.id.au, minipli@googlemail.com, tglx@linutronix.de, peterz@infradead.org, dvlasenk@redhat.com, re.emese@gmail.com, hpa@zytor.com, mingo@kernel.org, luto@amacapital.net, brgerst@gmail.com, linux-kernel@vger.kernel.org, pageexec@freemail.hu Mime-Version: =?UTF-8?B?MS4w?= Content-Type: =?UTF-8?B?dGV4dC9wbGFpbjsgY2hhcnNldD1VVEYtOA==?= Content-Transfer-Encoding: =?UTF-8?B?OGJpdA==?= Return-path: In-Reply-To: <1455748879-21872-3-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: minipli@googlemail.com, mpe@ellerman.id.au, linux-arch@vger.kernel.org, david.brown@linaro.org, arnd@arndb.de, keescook@chromium.org, bp@alien8.de, torvalds@linux-foundation.org, pageexec@freemail.hu, linux-kernel@vger.kernel.org, brgerst@gmail.com, luto@amacapital.net, mingo@kernel.org, tglx@linutronix.de, hpa@zytor.com, re.emese@gmail.com, peterz@infradead.org, dvlasenk@redhat.com List-Id: linux-arch.vger.kernel.org Commit-ID: d2aa1acad22f1bdd0cfa67b3861800e392254454 Gitweb: http://git.kernel.org/tip/d2aa1acad22f1bdd0cfa67b3861800e392254454 Author: Kees Cook AuthorDate: Wed, 17 Feb 2016 14:41:13 -0800 Committer: Ingo Molnar CommitDate: Mon, 22 Feb 2016 08:51:37 +0100 mm/init: Add 'rodata=off' boot cmdline parameter to disable read-only kernel mappings It may be useful to debug writes to the readonly sections of memory, so provide a cmdline "rodata=off" to allow for this. This can be expanded in the future to support "log" and "write" modes, but that will need to be architecture-specific. This also makes KDB software breakpoints more usable, as read-only mappings can now be disabled on any kernel. Suggested-by: H. Peter Anvin 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: 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/1455748879-21872-3-git-send-email-keescook@chromium.org Signed-off-by: Ingo Molnar --- Documentation/kernel-parameters.txt | 4 ++++ init/main.c | 27 +++++++++++++++++++++++---- kernel/debug/kdb/kdb_bp.c | 4 +--- 3 files changed, 28 insertions(+), 7 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 9a53c92..0003367 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -3491,6 +3491,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. ro [KNL] Mount root device read-only on boot + rodata= [KNL] + on Mark read-only kernel memory as read-only (default). + off Leave read-only kernel memory writable for debugging. + root= [KNL] Root filesystem See name_to_dev_t comment in init/do_mounts.c. diff --git a/init/main.c b/init/main.c index 58c9e37..928a343 100644 --- a/init/main.c +++ b/init/main.c @@ -93,9 +93,6 @@ static int kernel_init(void *); extern void init_IRQ(void); extern void fork_init(void); extern void radix_tree_init(void); -#ifndef CONFIG_DEBUG_RODATA -static inline void mark_rodata_ro(void) { } -#endif /* * Debug helper: via this flag we know that we are in 'early bootup code' @@ -929,6 +926,28 @@ static int try_to_run_init_process(const char *init_filename) static noinline void __init kernel_init_freeable(void); +#ifdef CONFIG_DEBUG_RODATA +static bool rodata_enabled = true; +static int __init set_debug_rodata(char *str) +{ + return strtobool(str, &rodata_enabled); +} +__setup("rodata=", set_debug_rodata); + +static void mark_readonly(void) +{ + if (rodata_enabled) + mark_rodata_ro(); + else + pr_info("Kernel memory protection disabled.\n"); +} +#else +static inline void mark_readonly(void) +{ + pr_warn("This architecture does not have kernel memory protection.\n"); +} +#endif + static int __ref kernel_init(void *unused) { int ret; @@ -937,7 +956,7 @@ static int __ref kernel_init(void *unused) /* need to finish all async __init code before freeing the memory */ async_synchronize_full(); free_initmem(); - mark_rodata_ro(); + mark_readonly(); system_state = SYSTEM_RUNNING; numa_default_policy(); diff --git a/kernel/debug/kdb/kdb_bp.c b/kernel/debug/kdb/kdb_bp.c index e1dbf4a..90ff129 100644 --- a/kernel/debug/kdb/kdb_bp.c +++ b/kernel/debug/kdb/kdb_bp.c @@ -153,13 +153,11 @@ static int _kdb_bp_install(struct pt_regs *regs, kdb_bp_t *bp) } else { kdb_printf("%s: failed to set breakpoint at 0x%lx\n", __func__, bp->bp_addr); -#ifdef CONFIG_DEBUG_RODATA if (!bp->bp_type) { kdb_printf("Software breakpoints are unavailable.\n" - " Change the kernel CONFIG_DEBUG_RODATA=n\n" + " Boot the kernel with rodata=off\n" " OR use hw breaks: help bph\n"); } -#endif return 1; } return 0; From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from terminus.zytor.com ([198.137.202.10]:58230 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753064AbcBWJKO (ORCPT ); Tue, 23 Feb 2016 04:10:14 -0500 Date: Mon, 22 Feb 2016 04:18:45 -0800 From: =?UTF-8?B?dGlwLWJvdCBmb3IgS2VlcyBDb29rIDx0aXBib3RAenl0b3IuY29tPg==?=@zytor.com Message-ID: Reply-To: arnd@arndb.de, david.brown@linaro.org, linux-arch@vger.kernel.org, torvalds@linux-foundation.org, keescook@chromium.org, bp@alien8.de, mpe@ellerman.id.au, minipli@googlemail.com, tglx@linutronix.de, peterz@infradead.org, dvlasenk@redhat.com, re.emese@gmail.com, hpa@zytor.com, mingo@kernel.org, luto@amacapital.net, brgerst@gmail.com, linux-kernel@vger.kernel.org, pageexec@freemail.hu In-Reply-To: <1455748879-21872-3-git-send-email-keescook@chromium.org> References: <1455748879-21872-3-git-send-email-keescook@chromium.org> Subject: =?UTF-8?B?W3RpcDptbS9yZWFkb25seV0gbW0vaW5pdDogQWRkICdyb2RhdGE9b2ZmJyBib28=?= =?UTF-8?B?dCBjbWRsaW5lIHBhcmFtZXRlciB0byBkaXNhYmxlIHJlYWQtb25seSBrZXJuZWw=?= =?UTF-8?B?IG1hcHBpbmdz?= 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: minipli@googlemail.com, mpe@ellerman.id.au, linux-arch@vger.kernel.org, david.brown@linaro.org, arnd@arndb.de, keescook@chromium.org, bp@alien8.de, torvalds@linux-foundation.org, pageexec@freemail.hu, linux-kernel@vger.kernel.org, brgerst@gmail.com, luto@amacapital.net, mingo@kernel.org, tglx@linutronix.de, hpa@zytor.com, re.emese@gmail.com, peterz@infradead.org, dvlasenk@redhat.com Message-ID: <20160222121845.sNgr6zMCbmFgcQJKtg1Z9J2y3XHwCe661Cf97ru-73I@z> Commit-ID: d2aa1acad22f1bdd0cfa67b3861800e392254454 Gitweb: http://git.kernel.org/tip/d2aa1acad22f1bdd0cfa67b3861800e392254454 Author: Kees Cook AuthorDate: Wed, 17 Feb 2016 14:41:13 -0800 Committer: Ingo Molnar CommitDate: Mon, 22 Feb 2016 08:51:37 +0100 mm/init: Add 'rodata=off' boot cmdline parameter to disable read-only kernel mappings It may be useful to debug writes to the readonly sections of memory, so provide a cmdline "rodata=off" to allow for this. This can be expanded in the future to support "log" and "write" modes, but that will need to be architecture-specific. This also makes KDB software breakpoints more usable, as read-only mappings can now be disabled on any kernel. Suggested-by: H. Peter Anvin 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: 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/1455748879-21872-3-git-send-email-keescook@chromium.org Signed-off-by: Ingo Molnar --- Documentation/kernel-parameters.txt | 4 ++++ init/main.c | 27 +++++++++++++++++++++++---- kernel/debug/kdb/kdb_bp.c | 4 +--- 3 files changed, 28 insertions(+), 7 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 9a53c92..0003367 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -3491,6 +3491,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. ro [KNL] Mount root device read-only on boot + rodata= [KNL] + on Mark read-only kernel memory as read-only (default). + off Leave read-only kernel memory writable for debugging. + root= [KNL] Root filesystem See name_to_dev_t comment in init/do_mounts.c. diff --git a/init/main.c b/init/main.c index 58c9e37..928a343 100644 --- a/init/main.c +++ b/init/main.c @@ -93,9 +93,6 @@ static int kernel_init(void *); extern void init_IRQ(void); extern void fork_init(void); extern void radix_tree_init(void); -#ifndef CONFIG_DEBUG_RODATA -static inline void mark_rodata_ro(void) { } -#endif /* * Debug helper: via this flag we know that we are in 'early bootup code' @@ -929,6 +926,28 @@ static int try_to_run_init_process(const char *init_filename) static noinline void __init kernel_init_freeable(void); +#ifdef CONFIG_DEBUG_RODATA +static bool rodata_enabled = true; +static int __init set_debug_rodata(char *str) +{ + return strtobool(str, &rodata_enabled); +} +__setup("rodata=", set_debug_rodata); + +static void mark_readonly(void) +{ + if (rodata_enabled) + mark_rodata_ro(); + else + pr_info("Kernel memory protection disabled.\n"); +} +#else +static inline void mark_readonly(void) +{ + pr_warn("This architecture does not have kernel memory protection.\n"); +} +#endif + static int __ref kernel_init(void *unused) { int ret; @@ -937,7 +956,7 @@ static int __ref kernel_init(void *unused) /* need to finish all async __init code before freeing the memory */ async_synchronize_full(); free_initmem(); - mark_rodata_ro(); + mark_readonly(); system_state = SYSTEM_RUNNING; numa_default_policy(); diff --git a/kernel/debug/kdb/kdb_bp.c b/kernel/debug/kdb/kdb_bp.c index e1dbf4a..90ff129 100644 --- a/kernel/debug/kdb/kdb_bp.c +++ b/kernel/debug/kdb/kdb_bp.c @@ -153,13 +153,11 @@ static int _kdb_bp_install(struct pt_regs *regs, kdb_bp_t *bp) } else { kdb_printf("%s: failed to set breakpoint at 0x%lx\n", __func__, bp->bp_addr); -#ifdef CONFIG_DEBUG_RODATA if (!bp->bp_type) { kdb_printf("Software breakpoints are unavailable.\n" - " Change the kernel CONFIG_DEBUG_RODATA=n\n" + " Boot the kernel with rodata=off\n" " OR use hw breaks: help bph\n"); } -#endif return 1; } return 0;