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: [PATCH v2 06/10] powerpc/8xx: Add Kernel Userspace Execution Prevention
Date: Mon, 11 Mar 2019 08:30:33 +0000 (UTC) [thread overview]
Message-ID: <4abe5532a0a3a6165342c5ff3ff76f18bf4cdef6.1552292207.git.christophe.leroy@c-s.fr> (raw)
In-Reply-To: <cover.1552292207.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/nohash/32/mmu-8xx.h | 7 +++++++
arch/powerpc/mm/8xx_mmu.c | 12 ++++++++++++
arch/powerpc/platforms/Kconfig.cputype | 1 +
3 files changed, 20 insertions(+)
diff --git a/arch/powerpc/include/asm/nohash/32/mmu-8xx.h b/arch/powerpc/include/asm/nohash/32/mmu-8xx.h
index fc5a653d5dd2..3cb743284e09 100644
--- a/arch/powerpc/include/asm/nohash/32/mmu-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/mmu-8xx.h
@@ -41,6 +41,13 @@
*/
#define MI_APG_INIT 0x4fffffff
+/*
+ * 0 => Kernel => 01 (all accesses performed according to page definition)
+ * 1 => User => 10 (all accesses performed according to swaped page definition)
+ * 2-16 => NA => 11 (all accesses performed as user iaw page definition)
+ */
+#define MI_APG_KUEP 0x6fffffff
+
/* 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 fe1f6443d57f..e257a0c9bd08 100644
--- a/arch/powerpc/mm/8xx_mmu.c
+++ b/arch/powerpc/mm/8xx_mmu.c
@@ -213,3 +213,15 @@ 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 2e45a6e2bc99..00fa0d110dcb 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -34,6 +34,7 @@ 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:[~2019-03-11 8:40 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-11 8:30 [PATCH v2 00/10] Kernel Userspace protection for PPC32 Christophe Leroy
2019-03-11 8:30 ` [PATCH v2 01/10] powerpc/6xx: fix setup and use of SPRN_SPRG_PGDIR for hash32 Christophe Leroy
2019-03-20 13:04 ` [v2, " Michael Ellerman
2019-03-11 8:30 ` [PATCH v2 02/10] powerpc/mm: Detect bad KUAP faults (Squash of v5 series) Christophe Leroy
2019-03-11 8:30 ` [PATCH v2 03/10] powerpc/32: Remove MSR_PR test when returning from syscall Christophe Leroy
2019-04-21 14:18 ` [v2, " Michael Ellerman
2019-03-11 8:30 ` [PATCH v2 04/10] powerpc/32: Prepare for Kernel Userspace Access Protection Christophe Leroy
2019-03-11 8:30 ` [PATCH v2 05/10] powerpc/8xx: Only define APG0 and APG1 Christophe Leroy
2019-03-11 8:30 ` Christophe Leroy [this message]
2019-03-11 8:30 ` [PATCH v2 07/10] powerpc/8xx: Add Kernel Userspace Access Protection Christophe Leroy
2019-04-18 6:53 ` Michael Ellerman
2019-03-11 8:30 ` [PATCH v2 08/10] powerpc/32s: Implement Kernel Userspace Execution Prevention Christophe Leroy
2019-03-11 8:30 ` [PATCH v2 09/10] powerpc/32s: Prepare Kernel Userspace Access Protection Christophe Leroy
2019-03-11 8:30 ` [PATCH v2 10/10] powerpc/32s: Implement " Christophe Leroy
2019-04-18 6:55 ` Michael Ellerman
2019-04-23 9:26 ` Christophe Leroy
2020-01-21 17:22 ` GCC bug ? " Christophe Leroy
2020-01-21 19:55 ` Segher Boessenkool
2020-01-22 6:52 ` Christophe Leroy
2020-01-22 13:36 ` Segher Boessenkool
2020-01-22 14:45 ` Christophe Leroy
2020-01-22 6:57 ` Christophe Leroy
2020-01-22 13:18 ` Segher Boessenkool
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