From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
ruscur@russell.cc
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: [RFC PATCH v2 05/11] powerpc/8xx: Add Kernel Userspace Execution Prevention
Date: Wed, 28 Nov 2018 09:27:12 +0000 (UTC) [thread overview]
Message-ID: <de304421c38858ddbf3162433e0a6ca326719a52.1543356926.git.christophe.leroy@c-s.fr> (raw)
In-Reply-To: <76d777b36e54e7b8d4c196405decc712fc5eaf45.1543356926.git.christophe.leroy@c-s.fr>
This patch adds Kernel Userspace Execution Prevention on the 8xx.
When a page is Executable, it is set Executable for Key 0 and NX
for Key 1.
Up to now, the User group is defined with Key 0 for both User and
Supervisor.
By changing the group to Key 0 for User and Key 1 for Supervisor,
this patch prevents the Kernel from being able to execute user code.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
arch/powerpc/include/asm/mmu-8xx.h | 6 ++++++
arch/powerpc/mm/8xx_mmu.c | 12 ++++++++++++
arch/powerpc/platforms/Kconfig.cputype | 1 +
3 files changed, 19 insertions(+)
diff --git a/arch/powerpc/include/asm/mmu-8xx.h b/arch/powerpc/include/asm/mmu-8xx.h
index fa05aa566ece..53dbf0788fce 100644
--- a/arch/powerpc/include/asm/mmu-8xx.h
+++ b/arch/powerpc/include/asm/mmu-8xx.h
@@ -41,6 +41,12 @@
*/
#define MI_APG_INIT 0x44444444
+/*
+ * 0 => No user => 01 (all accesses performed according to page definition)
+ * 1 => User => 10 (all accesses performed according to swaped page definition)
+ */
+#define MI_APG_KUEP 0x66666666
+
/* The effective page number register. When read, contains the information
* about the last instruction TLB miss. When MI_RPN is written, bits in
* this register are used to create the TLB entry.
diff --git a/arch/powerpc/mm/8xx_mmu.c b/arch/powerpc/mm/8xx_mmu.c
index 01b7f5107c3a..f14ceb507d98 100644
--- a/arch/powerpc/mm/8xx_mmu.c
+++ b/arch/powerpc/mm/8xx_mmu.c
@@ -194,3 +194,15 @@ void flush_instruction_cache(void)
mtspr(SPRN_IC_CST, IDC_INVALL);
isync();
}
+
+#ifdef CONFIG_PPC_KUEP
+void __init setup_kuep(bool disabled)
+{
+ if (disabled)
+ return;
+
+ pr_info("Activating Kernel Userspace Execution Prevention\n");
+
+ mtspr(SPRN_MI_AP, MI_APG_KUEP);
+}
+#endif
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 68eaafd54aca..d1757cedf60b 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -33,6 +33,7 @@ config PPC_8xx
bool "Freescale 8xx"
select FSL_SOC
select SYS_SUPPORTS_HUGETLBFS
+ select PPC_HAVE_KUEP
config 40x
bool "AMCC 40x"
--
2.13.3
next prev parent reply other threads:[~2018-11-28 9:39 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-28 9:27 [PATCH v2 01/11] powerpc/mm: Fix reporting of kernel execute faults on the 8xx Christophe Leroy
2018-11-28 9:27 ` [RFC PATCH v2 02/11] powerpc: Add framework for Kernel Userspace Protection Christophe Leroy
2018-11-28 9:27 ` [RFC PATCH v2 03/11] powerpc: Add skeleton for Kernel Userspace Execution Prevention Christophe Leroy
2018-11-28 9:27 ` [RFC PATCH v2 04/11] powerpc/mm: Add a framework for Kernel Userspace Access Protection Christophe Leroy
2018-12-21 5:07 ` Michael Ellerman
2018-12-21 6:48 ` Christophe Leroy
2018-11-28 9:27 ` Christophe Leroy [this message]
2018-11-28 9:27 ` [RFC PATCH v2 06/11] powerpc/8xx: Add " Christophe Leroy
2018-11-28 9:27 ` [RFC PATCH v2 07/11] powerpc/mm/radix: Use KUEP API for Radix MMU Russell Currey
2018-11-28 9:43 ` Christophe Leroy
2018-11-28 9:46 ` Christophe LEROY
2018-11-28 9:27 ` [RFC PATCH v2 08/11] powerpc/64s: Implement KUAP " Russell Currey
2018-11-28 9:43 ` Christophe Leroy
2018-11-28 9:27 ` [RFC PATCH v2 09/11] powerpc/32: add helper to write into segment registers Christophe Leroy
2018-11-28 9:27 ` [RFC PATCH v2 10/11] powerpc/book3s32: Prepare Kernel Userspace Access Protection Christophe Leroy
2018-11-28 9:27 ` [RFC PATCH v2 11/11] powerpc/book3s32: Implement " Christophe Leroy
2018-12-11 5:25 ` Russell Currey
2018-12-11 20:46 ` Christophe Leroy
2018-12-23 13:27 ` [v2, 01/11] powerpc/mm: Fix reporting of kernel execute faults on the 8xx Michael Ellerman
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