From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Kees Cook <keescook@chromium.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Ingo Molnar <mingo@kernel.org>,
David Brown <david.brown@linaro.org>,
Andy Lutomirski <luto@amacapital.net>,
"H. Peter Anvin" <hpa@zytor.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Mathias Krause <minipli@googlemail.com>,
Thomas Gleixner <tglx@linutronix.de>,
"x86@kernel.org" <x86@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
PaX Team <pageexec@freemail.hu>, Emese Revfy <re.emese@gmail.com>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
linux-s390 <linux-s390@vger.kernel.org>
Subject: [kernel-hardening] Re: [RFC][PATCH] s390, postinit-readonly: implement post-init RO
Date: Tue, 8 Mar 2016 09:51:05 +0100 [thread overview]
Message-ID: <56DE9279.6040805@de.ibm.com> (raw)
In-Reply-To: <CAGXu5jLu5NFw=7xoJEYcAq7MFwGY1nuB8w-q+NVp2d2zpwRUyQ@mail.gmail.com>
On 03/08/2016 01:41 AM, Kees Cook wrote:
>> --- a/arch/s390/kernel/vmlinux.lds.S
>> +++ b/arch/s390/kernel/vmlinux.lds.S
>> @@ -52,6 +52,12 @@ SECTIONS
>>
>> RW_DATA_SECTION(0x100, PAGE_SIZE, THREAD_SIZE)
>>
>> + . = ALIGN(PAGE_SIZE)
missing ";" ?
With that and your fixes, this function claims to mark 0kB and
lkdtm can still write. Reason is that _edata is 0xc11008 and start is
0x0c11000.
making _edata page aligned as well, does now try to mark one page, but then
we run into the next issue, that
static void change_page_attr(unsigned long addr, int numpages,
pte_t (*set) (pte_t))
{
pte_t *ptep;
int i;
for (i = 0; i < numpages; i++) {
ptep = walk_page_table(addr);
triggers this
if (WARN_ON_ONCE(!ptep))
break;
because the kernel decided to map this with a large page. So we need
to fix this function to then break the large page into a smaller chunk....
Christian
WARNING: multiple messages have this Message-ID (diff)
From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Kees Cook <keescook@chromium.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Ingo Molnar <mingo@kernel.org>,
David Brown <david.brown@linaro.org>,
Andy Lutomirski <luto@amacapital.net>,
"H. Peter Anvin" <hpa@zytor.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Mathias Krause <minipli@googlemail.com>,
Thomas Gleixner <tglx@linutronix.de>,
"x86@kernel.org" <x86@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
PaX Team <pageexec@freemail.hu>, Emese Revfy <re.emese@gmail.com>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
linux-s390 <linux-s390@vger.kernel.org>
Subject: Re: [RFC][PATCH] s390, postinit-readonly: implement post-init RO
Date: Tue, 8 Mar 2016 09:51:05 +0100 [thread overview]
Message-ID: <56DE9279.6040805@de.ibm.com> (raw)
In-Reply-To: <CAGXu5jLu5NFw=7xoJEYcAq7MFwGY1nuB8w-q+NVp2d2zpwRUyQ@mail.gmail.com>
On 03/08/2016 01:41 AM, Kees Cook wrote:
>> --- a/arch/s390/kernel/vmlinux.lds.S
>> +++ b/arch/s390/kernel/vmlinux.lds.S
>> @@ -52,6 +52,12 @@ SECTIONS
>>
>> RW_DATA_SECTION(0x100, PAGE_SIZE, THREAD_SIZE)
>>
>> + . = ALIGN(PAGE_SIZE)
missing ";" ?
With that and your fixes, this function claims to mark 0kB and
lkdtm can still write. Reason is that _edata is 0xc11008 and start is
0x0c11000.
making _edata page aligned as well, does now try to mark one page, but then
we run into the next issue, that
static void change_page_attr(unsigned long addr, int numpages,
pte_t (*set) (pte_t))
{
pte_t *ptep;
int i;
for (i = 0; i < numpages; i++) {
ptep = walk_page_table(addr);
triggers this
if (WARN_ON_ONCE(!ptep))
break;
because the kernel decided to map this with a large page. So we need
to fix this function to then break the large page into a smaller chunk....
Christian
next prev parent reply other threads:[~2016-03-08 8:51 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-08 0:20 [kernel-hardening] [RFC][PATCH] s390, postinit-readonly: implement post-init RO Kees Cook
2016-03-08 0:20 ` Kees Cook
2016-03-08 0:41 ` [kernel-hardening] " Kees Cook
2016-03-08 0:41 ` Kees Cook
2016-03-08 8:51 ` Christian Borntraeger [this message]
2016-03-08 8:51 ` Christian Borntraeger
2016-03-08 11:43 ` [kernel-hardening] " Heiko Carstens
2016-03-08 11:43 ` Heiko Carstens
2016-03-08 12:56 ` [kernel-hardening] " Heiko Carstens
2016-03-08 12:56 ` Heiko Carstens
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