From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: [PATCH v2 1/4] init: create cmdline param to disable readonly Date: Wed, 25 Nov 2015 16:44:02 -0800 Message-ID: <20151126004402.GA30235@kroah.com> References: <1448494286-16029-1-git-send-email-keescook@chromium.org> <1448494286-16029-2-git-send-email-keescook@chromium.org> Reply-To: kernel-hardening@lists.openwall.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Content-Disposition: inline In-Reply-To: <1448494286-16029-2-git-send-email-keescook@chromium.org> To: kernel-hardening@lists.openwall.com Cc: linux-kernel@vger.kernel.org, Kees Cook , Andy Lutomirski , "H. Peter Anvin" , Michael Ellerman , Mathias Krause , Ingo Molnar , Thomas Gleixner , x86@kernel.org, Arnd Bergmann , PaX Team , Emese Revfy , linux-arch List-Id: linux-arch.vger.kernel.org On Wed, Nov 25, 2015 at 03:31:23PM -0800, Kees Cook wrote: > It may be useful to debug writes to the readonly sections of memory, > so provide a cmdline "rodata=off" to allow for this. > > Suggested-by: H. Peter Anvin > Signed-off-by: Kees Cook > --- > Documentation/kernel-parameters.txt | 4 ++++ > init/main.c | 31 +++++++++++++++++++++++++++---- > 2 files changed, 31 insertions(+), 4 deletions(-) > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 742f69d18fc8..21cf76dbba90 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -3409,6 +3409,10 @@ 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 9e64d7097f1a..06200d2fbf08 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 +926,32 @@ static int try_to_run_init_process(const char *init_filename) > > static noinline void __init kernel_init_freeable(void); > > +#ifdef CONFIG_DEBUG_RODATA > +bool disable_mark_readonly; > +static int __init set_debug_rodata(char *str) > +{ > + if (!str) > + return -EINVAL; > + if (!strncmp(str, "on", 2)) > + disable_mark_readonly = false; > + else if (!strncmp(str, "off", 3)) > + disable_mark_readonly = true; strtobool()? From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out2-smtp.messagingengine.com ([66.111.4.26]:59176 "EHLO out2-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752497AbbKZBGy (ORCPT ); Wed, 25 Nov 2015 20:06:54 -0500 Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailout.nyi.internal (Postfix) with ESMTP id C90C620BC1 for ; Wed, 25 Nov 2015 20:06:53 -0500 (EST) Date: Wed, 25 Nov 2015 16:44:02 -0800 From: Greg KH Subject: Re: [kernel-hardening] [PATCH v2 1/4] init: create cmdline param to disable readonly Message-ID: <20151126004402.GA30235@kroah.com> References: <1448494286-16029-1-git-send-email-keescook@chromium.org> <1448494286-16029-2-git-send-email-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1448494286-16029-2-git-send-email-keescook@chromium.org> Sender: linux-arch-owner@vger.kernel.org List-ID: To: kernel-hardening@lists.openwall.com Cc: linux-kernel@vger.kernel.org, Kees Cook , Andy Lutomirski , "H. Peter Anvin" , Michael Ellerman , Mathias Krause , Ingo Molnar , Thomas Gleixner , x86@kernel.org, Arnd Bergmann , PaX Team , Emese Revfy , linux-arch Message-ID: <20151126004402.xpiqf-Nb_ZdAGWnH6f9zSNTjvlJD0NElOzeDkLjDhuQ@z> On Wed, Nov 25, 2015 at 03:31:23PM -0800, Kees Cook wrote: > It may be useful to debug writes to the readonly sections of memory, > so provide a cmdline "rodata=off" to allow for this. > > Suggested-by: H. Peter Anvin > Signed-off-by: Kees Cook > --- > Documentation/kernel-parameters.txt | 4 ++++ > init/main.c | 31 +++++++++++++++++++++++++++---- > 2 files changed, 31 insertions(+), 4 deletions(-) > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 742f69d18fc8..21cf76dbba90 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -3409,6 +3409,10 @@ 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 9e64d7097f1a..06200d2fbf08 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 +926,32 @@ static int try_to_run_init_process(const char *init_filename) > > static noinline void __init kernel_init_freeable(void); > > +#ifdef CONFIG_DEBUG_RODATA > +bool disable_mark_readonly; > +static int __init set_debug_rodata(char *str) > +{ > + if (!str) > + return -EINVAL; > + if (!strncmp(str, "on", 2)) > + disable_mark_readonly = false; > + else if (!strncmp(str, "off", 3)) > + disable_mark_readonly = true; strtobool()?