[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Mon, 27 Feb 2017 12:43:02 -0800
From: Kees Cook <keescook@...omium.org>
To: kernel-hardening@...ts.openwall.com
Cc: Kees Cook <keescook@...omium.org>,
Mark Rutland <mark.rutland@....com>,
Andy Lutomirski <luto@...nel.org>,
Hoeun Ryu <hoeun.ryu@...il.com>,
PaX Team <pageexec@...email.hu>,
Emese Revfy <re.emese@...il.com>,
Russell King <linux@...linux.org.uk>,
x86@...nel.org
Subject: [RFC][PATCH 4/8] x86: Implement __arch_rare_write_map/unmap()
Based on PaX's x86 pax_{open,close}_kernel() implementation, this
allows HAVE_ARCH_RARE_WRITE to work on x86.
There is missing work to sort out some header file issues where preempt.h
is missing, though it can't be included in pg_table.h unconditionally...
some other solution will be needed, perhaps an entirely separate header
file for rare_write()-related defines...
This patch is also missing paravirt support.
Signed-off-by: Kees Cook <keescook@...omium.org>
---
arch/x86/Kconfig | 1 +
arch/x86/include/asm/pgtable.h | 31 +++++++++++++++++++++++++++++++
2 files changed, 32 insertions(+)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e487493bbd47..6d4d6f73d4b8 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -102,6 +102,7 @@ config X86
select HAVE_ARCH_KMEMCHECK
select HAVE_ARCH_MMAP_RND_BITS if MMU
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
+ select HAVE_ARCH_RARE_WRITE
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 437feb436efa..86e78e97738f 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -90,6 +90,37 @@ extern struct mm_struct *pgd_page_get_mm(struct page *page);
#endif /* CONFIG_PARAVIRT */
+/* TODO: Bad hack to deal with preempt macros being missing sometimes. */
+#ifndef preempt_disable
+#include <linux/preempt.h>
+#endif
+
+static inline unsigned long __arch_rare_write_map(void)
+{
+ unsigned long cr0;
+
+ preempt_disable();
+ barrier();
+ cr0 = read_cr0() ^ X86_CR0_WP;
+ BUG_ON(cr0 & X86_CR0_WP);
+ write_cr0(cr0);
+ barrier();
+ return cr0 ^ X86_CR0_WP;
+}
+
+static inline unsigned long __arch_rare_write_unmap(void)
+{
+ unsigned long cr0;
+
+ barrier();
+ cr0 = read_cr0() ^ X86_CR0_WP;
+ BUG_ON(!(cr0 & X86_CR0_WP));
+ write_cr0(cr0);
+ barrier();
+ preempt_enable_no_resched();
+ return cr0 ^ X86_CR0_WP;
+}
+
/*
* The following only work if pte_present() is true.
* Undefined behaviour if not..
--
2.7.4
Powered by blists - more mailing lists
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
