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* [PATCH v3 0/7] arm: support CONFIG_RODATA
@ 2014-08-12 18:24 ` Kees Cook
  0 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 18:24 UTC (permalink / raw)
  To: linux-kernel
  Cc: Kees Cook, Laura Abbott, Rob Herring, Leif Lindholm, Mark Salter,
	Rabin Vincent, Liu hua, Nikolay Borisov, Nicolas Pitre,
	Tomasz Figa, Doug Anderson, Jason Wessel, Will Deacon,
	Catalin Marinas, Russell King - ARM Linux, linux-arm-kernel

This is a series of patches to support CONFIG_RODATA on ARM, so that
the kernel text is RO, and non-text sections default to NX. To support
on-the-fly kernel text patching (via ftrace, kprobes, etc), fixmap
support has been finalized based on several versions of various patches
that are floating around on the mailing list. This series attempts to
include the least intrusive version, so that others can build on it for
future fixmap work.

The series has been heavily tested, and appears to be working correctly:

With CONFIG_ARM_PTDUMP, expected page table permissions are seen in
/sys/kernel/debug/kernel_page_tables.

Using CONFIG_LKDTM, the kernel now correctly detects bad accesses for
for the following lkdtm tests via /sys/kernel/debug/provoke-crash/DIRECT:
        EXEC_DATA
        WRITE_RO
        WRITE_KERN

ftrace works:
        CONFIG_FTRACE_STARTUP_TEST passes
        Enabling tracing works:
                echo function > /sys/kernel/debug/tracing/current_tracer

kprobes works:
        CONFIG_ARM_KPROBES_TEST passes

kexec works:
        kexec will load and start a new kernel

Built with and without CONFIG_HIGHMEM. Current limitation on fixmap is
that builds do not support 32 CPUs (max 31). This will be addressed by
additional patches to expand the fixmap to 3MB.

Thanks to everyone who has been testing this series and working on its
various pieces!

-Kees

v3:
- more cleanups in switch to generic fixmap (lauraa, robh)
- fixed kexec merge hunk glitch (will.deacon)
- added tested-by tags where appropriate from v2 testing

v2:
- fix typo in kexec merge (buildbot)
- flip index order for highmem pte access (lauraa)
- added kgdb updates (dianders)



^ permalink raw reply	[flat|nested] 30+ messages in thread
* [PATCH v3 0/7] arm: support CONFIG_RODATA
@ 2014-08-12 18:24 ` Kees Cook
  0 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 18:24 UTC (permalink / raw)
  To: linux-arm-kernel

This is a series of patches to support CONFIG_RODATA on ARM, so that
the kernel text is RO, and non-text sections default to NX. To support
on-the-fly kernel text patching (via ftrace, kprobes, etc), fixmap
support has been finalized based on several versions of various patches
that are floating around on the mailing list. This series attempts to
include the least intrusive version, so that others can build on it for
future fixmap work.

The series has been heavily tested, and appears to be working correctly:

With CONFIG_ARM_PTDUMP, expected page table permissions are seen in
/sys/kernel/debug/kernel_page_tables.

Using CONFIG_LKDTM, the kernel now correctly detects bad accesses for
for the following lkdtm tests via /sys/kernel/debug/provoke-crash/DIRECT:
        EXEC_DATA
        WRITE_RO
        WRITE_KERN

ftrace works:
        CONFIG_FTRACE_STARTUP_TEST passes
        Enabling tracing works:
                echo function > /sys/kernel/debug/tracing/current_tracer

kprobes works:
        CONFIG_ARM_KPROBES_TEST passes

kexec works:
        kexec will load and start a new kernel

Built with and without CONFIG_HIGHMEM. Current limitation on fixmap is
that builds do not support 32 CPUs (max 31). This will be addressed by
additional patches to expand the fixmap to 3MB.

Thanks to everyone who has been testing this series and working on its
various pieces!

-Kees

v3:
- more cleanups in switch to generic fixmap (lauraa, robh)
- fixed kexec merge hunk glitch (will.deacon)
- added tested-by tags where appropriate from v2 testing

v2:
- fix typo in kexec merge (buildbot)
- flip index order for highmem pte access (lauraa)
- added kgdb updates (dianders)

^ permalink raw reply	[flat|nested] 30+ messages in thread
* [PATCH v3 1/7] arm: use generic fixmap.h
  2014-08-12 18:24 ` Kees Cook
@ 2014-08-12 18:24   ` Kees Cook
  -1 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 18:24 UTC (permalink / raw)
  To: linux-kernel
  Cc: Kees Cook, Mark Salter, Laura Abbott, Rob Herring, Leif Lindholm,
	Rabin Vincent, Liu hua, Nikolay Borisov, Nicolas Pitre,
	Tomasz Figa, Doug Anderson, Jason Wessel, Will Deacon,
	Catalin Marinas, Russell King - ARM Linux, linux-arm-kernel

From: Mark Salter <msalter@redhat.com>

ARM is different from other architectures in that fixmap pages are indexed
with a positive offset from FIXADDR_START.  Other architectures index with
a negative offset from FIXADDR_TOP.  In order to use the generic fixmap.h
definitions, this patch redefines FIXADDR_TOP to be inclusive of the
useable range.  That is, FIXADDR_TOP is the virtual address of the topmost
fixed page.  The newly defined FIXADDR_END is the first virtual address
past the fixed mappings.

Signed-off-by: Mark Salter <msalter@redhat.com>
Reviewed-by: Doug Anderson <dianders@chromium.org>
[kees: update for a05e54c103b0b8 "ARM: 8031/2: change fixmap ..."]
[kees: fixed highmem usage, thanks to Laura Abbott and Rob Herring]
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Rob Herring <robh@kernel.org>
---
 arch/arm/include/asm/fixmap.h  | 27 +++++++++------------------
 arch/arm/include/asm/highmem.h |  1 -
 arch/arm/mm/highmem.c          | 15 ++++++++-------
 arch/arm/mm/init.c             |  2 +-
 arch/arm/mm/mmu.c              |  6 +++---
 5 files changed, 21 insertions(+), 30 deletions(-)

diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index 74124b0d0d79..a7add6f9315d 100644
--- a/arch/arm/include/asm/fixmap.h
+++ b/arch/arm/include/asm/fixmap.h
@@ -2,27 +2,18 @@
 #define _ASM_FIXMAP_H
 
 #define FIXADDR_START		0xffc00000UL
-#define FIXADDR_TOP		0xffe00000UL
-#define FIXADDR_SIZE		(FIXADDR_TOP - FIXADDR_START)
+#define FIXADDR_END		0xffe00000UL
+#define FIXADDR_TOP		(FIXADDR_END - PAGE_SIZE)
 
-#define FIX_KMAP_NR_PTES	(FIXADDR_SIZE >> PAGE_SHIFT)
+#include <asm/kmap_types.h>
 
-#define __fix_to_virt(x)	(FIXADDR_START + ((x) << PAGE_SHIFT))
-#define __virt_to_fix(x)	(((x) - FIXADDR_START) >> PAGE_SHIFT)
+enum fixed_addresses {
+	FIX_KMAP_BEGIN,
+	FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * NR_CPUS) - 1,
 
-extern void __this_fixmap_does_not_exist(void);
+	__end_of_fixed_addresses
+};
 
-static inline unsigned long fix_to_virt(const unsigned int idx)
-{
-	if (idx >= FIX_KMAP_NR_PTES)
-		__this_fixmap_does_not_exist();
-	return __fix_to_virt(idx);
-}
-
-static inline unsigned int virt_to_fix(const unsigned long vaddr)
-{
-	BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
-	return __virt_to_fix(vaddr);
-}
+#include <asm-generic/fixmap.h>
 
 #endif
diff --git a/arch/arm/include/asm/highmem.h b/arch/arm/include/asm/highmem.h
index 535579511ed0..91b99abe7a95 100644
--- a/arch/arm/include/asm/highmem.h
+++ b/arch/arm/include/asm/highmem.h
@@ -18,7 +18,6 @@
 	} while (0)
 
 extern pte_t *pkmap_page_table;
-extern pte_t *fixmap_page_table;
 
 extern void *kmap_high(struct page *page);
 extern void kunmap_high(struct page *page);
diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
index 45aeaaca9052..f87e0b89b738 100644
--- a/arch/arm/mm/highmem.c
+++ b/arch/arm/mm/highmem.c
@@ -18,19 +18,20 @@
 #include <asm/tlbflush.h>
 #include "mm.h"
 
-pte_t *fixmap_page_table;
-
 static inline void set_fixmap_pte(int idx, pte_t pte)
 {
 	unsigned long vaddr = __fix_to_virt(idx);
-	set_pte_ext(fixmap_page_table + idx, pte, 0);
+	pte_t *ppte = pte_offset_kernel(pmd_off_k(FIXADDR_START), vaddr);
+
+	set_pte_ext(ppte, pte, 0);
 	local_flush_tlb_kernel_page(vaddr);
 }
 
 static inline pte_t get_fixmap_pte(unsigned long vaddr)
 {
-	unsigned long idx = __virt_to_fix(vaddr);
-	return *(fixmap_page_table + idx);
+	pte_t *ppte = pte_offset_kernel(pmd_off_k(FIXADDR_START), vaddr);
+
+	return *ppte;
 }
 
 void *kmap(struct page *page)
@@ -84,7 +85,7 @@ void *kmap_atomic(struct page *page)
 	 * With debugging enabled, kunmap_atomic forces that entry to 0.
 	 * Make sure it was indeed properly unmapped.
 	 */
-	BUG_ON(!pte_none(*(fixmap_page_table + idx)));
+	BUG_ON(!pte_none(*get_fixmap_pte(vaddr)));
 #endif
 	/*
 	 * When debugging is off, kunmap_atomic leaves the previous mapping
@@ -134,7 +135,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
 	idx = type + KM_TYPE_NR * smp_processor_id();
 	vaddr = __fix_to_virt(idx);
 #ifdef CONFIG_DEBUG_HIGHMEM
-	BUG_ON(!pte_none(*(fixmap_page_table + idx)));
+	BUG_ON(!pte_none(*get_fixmap_pte(vaddr)));
 #endif
 	set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
 
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 659c75d808dc..ad82c05bfc3a 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -570,7 +570,7 @@ void __init mem_init(void)
 			MLK(DTCM_OFFSET, (unsigned long) dtcm_end),
 			MLK(ITCM_OFFSET, (unsigned long) itcm_end),
 #endif
-			MLK(FIXADDR_START, FIXADDR_TOP),
+			MLK(FIXADDR_START, FIXADDR_END),
 			MLM(VMALLOC_START, VMALLOC_END),
 			MLM(PAGE_OFFSET, (unsigned long)high_memory),
 #ifdef CONFIG_HIGHMEM
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 8348ed6b2efe..7fa0966cd15f 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -1326,10 +1326,10 @@ static void __init kmap_init(void)
 #ifdef CONFIG_HIGHMEM
 	pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE),
 		PKMAP_BASE, _PAGE_KERNEL_TABLE);
-
-	fixmap_page_table = early_pte_alloc(pmd_off_k(FIXADDR_START),
-		FIXADDR_START, _PAGE_KERNEL_TABLE);
 #endif
+
+	early_pte_alloc(pmd_off_k(FIXADDR_START), FIXADDR_START,
+			_PAGE_KERNEL_TABLE);
 }
 
 static void __init map_lowmem(void)
-- 
1.9.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread
* [PATCH v3 1/7] arm: use generic fixmap.h
@ 2014-08-12 18:24   ` Kees Cook
  0 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 18:24 UTC (permalink / raw)
  To: linux-arm-kernel

From: Mark Salter <msalter@redhat.com>

ARM is different from other architectures in that fixmap pages are indexed
with a positive offset from FIXADDR_START.  Other architectures index with
a negative offset from FIXADDR_TOP.  In order to use the generic fixmap.h
definitions, this patch redefines FIXADDR_TOP to be inclusive of the
useable range.  That is, FIXADDR_TOP is the virtual address of the topmost
fixed page.  The newly defined FIXADDR_END is the first virtual address
past the fixed mappings.

Signed-off-by: Mark Salter <msalter@redhat.com>
Reviewed-by: Doug Anderson <dianders@chromium.org>
[kees: update for a05e54c103b0b8 "ARM: 8031/2: change fixmap ..."]
[kees: fixed highmem usage, thanks to Laura Abbott and Rob Herring]
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Rob Herring <robh@kernel.org>
---
 arch/arm/include/asm/fixmap.h  | 27 +++++++++------------------
 arch/arm/include/asm/highmem.h |  1 -
 arch/arm/mm/highmem.c          | 15 ++++++++-------
 arch/arm/mm/init.c             |  2 +-
 arch/arm/mm/mmu.c              |  6 +++---
 5 files changed, 21 insertions(+), 30 deletions(-)

diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index 74124b0d0d79..a7add6f9315d 100644
--- a/arch/arm/include/asm/fixmap.h
+++ b/arch/arm/include/asm/fixmap.h
@@ -2,27 +2,18 @@
 #define _ASM_FIXMAP_H
 
 #define FIXADDR_START		0xffc00000UL
-#define FIXADDR_TOP		0xffe00000UL
-#define FIXADDR_SIZE		(FIXADDR_TOP - FIXADDR_START)
+#define FIXADDR_END		0xffe00000UL
+#define FIXADDR_TOP		(FIXADDR_END - PAGE_SIZE)
 
-#define FIX_KMAP_NR_PTES	(FIXADDR_SIZE >> PAGE_SHIFT)
+#include <asm/kmap_types.h>
 
-#define __fix_to_virt(x)	(FIXADDR_START + ((x) << PAGE_SHIFT))
-#define __virt_to_fix(x)	(((x) - FIXADDR_START) >> PAGE_SHIFT)
+enum fixed_addresses {
+	FIX_KMAP_BEGIN,
+	FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * NR_CPUS) - 1,
 
-extern void __this_fixmap_does_not_exist(void);
+	__end_of_fixed_addresses
+};
 
-static inline unsigned long fix_to_virt(const unsigned int idx)
-{
-	if (idx >= FIX_KMAP_NR_PTES)
-		__this_fixmap_does_not_exist();
-	return __fix_to_virt(idx);
-}
-
-static inline unsigned int virt_to_fix(const unsigned long vaddr)
-{
-	BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
-	return __virt_to_fix(vaddr);
-}
+#include <asm-generic/fixmap.h>
 
 #endif
diff --git a/arch/arm/include/asm/highmem.h b/arch/arm/include/asm/highmem.h
index 535579511ed0..91b99abe7a95 100644
--- a/arch/arm/include/asm/highmem.h
+++ b/arch/arm/include/asm/highmem.h
@@ -18,7 +18,6 @@
 	} while (0)
 
 extern pte_t *pkmap_page_table;
-extern pte_t *fixmap_page_table;
 
 extern void *kmap_high(struct page *page);
 extern void kunmap_high(struct page *page);
diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
index 45aeaaca9052..f87e0b89b738 100644
--- a/arch/arm/mm/highmem.c
+++ b/arch/arm/mm/highmem.c
@@ -18,19 +18,20 @@
 #include <asm/tlbflush.h>
 #include "mm.h"
 
-pte_t *fixmap_page_table;
-
 static inline void set_fixmap_pte(int idx, pte_t pte)
 {
 	unsigned long vaddr = __fix_to_virt(idx);
-	set_pte_ext(fixmap_page_table + idx, pte, 0);
+	pte_t *ppte = pte_offset_kernel(pmd_off_k(FIXADDR_START), vaddr);
+
+	set_pte_ext(ppte, pte, 0);
 	local_flush_tlb_kernel_page(vaddr);
 }
 
 static inline pte_t get_fixmap_pte(unsigned long vaddr)
 {
-	unsigned long idx = __virt_to_fix(vaddr);
-	return *(fixmap_page_table + idx);
+	pte_t *ppte = pte_offset_kernel(pmd_off_k(FIXADDR_START), vaddr);
+
+	return *ppte;
 }
 
 void *kmap(struct page *page)
@@ -84,7 +85,7 @@ void *kmap_atomic(struct page *page)
 	 * With debugging enabled, kunmap_atomic forces that entry to 0.
 	 * Make sure it was indeed properly unmapped.
 	 */
-	BUG_ON(!pte_none(*(fixmap_page_table + idx)));
+	BUG_ON(!pte_none(*get_fixmap_pte(vaddr)));
 #endif
 	/*
 	 * When debugging is off, kunmap_atomic leaves the previous mapping
@@ -134,7 +135,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
 	idx = type + KM_TYPE_NR * smp_processor_id();
 	vaddr = __fix_to_virt(idx);
 #ifdef CONFIG_DEBUG_HIGHMEM
-	BUG_ON(!pte_none(*(fixmap_page_table + idx)));
+	BUG_ON(!pte_none(*get_fixmap_pte(vaddr)));
 #endif
 	set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
 
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 659c75d808dc..ad82c05bfc3a 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -570,7 +570,7 @@ void __init mem_init(void)
 			MLK(DTCM_OFFSET, (unsigned long) dtcm_end),
 			MLK(ITCM_OFFSET, (unsigned long) itcm_end),
 #endif
-			MLK(FIXADDR_START, FIXADDR_TOP),
+			MLK(FIXADDR_START, FIXADDR_END),
 			MLM(VMALLOC_START, VMALLOC_END),
 			MLM(PAGE_OFFSET, (unsigned long)high_memory),
 #ifdef CONFIG_HIGHMEM
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 8348ed6b2efe..7fa0966cd15f 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -1326,10 +1326,10 @@ static void __init kmap_init(void)
 #ifdef CONFIG_HIGHMEM
 	pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE),
 		PKMAP_BASE, _PAGE_KERNEL_TABLE);
-
-	fixmap_page_table = early_pte_alloc(pmd_off_k(FIXADDR_START),
-		FIXADDR_START, _PAGE_KERNEL_TABLE);
 #endif
+
+	early_pte_alloc(pmd_off_k(FIXADDR_START), FIXADDR_START,
+			_PAGE_KERNEL_TABLE);
 }
 
 static void __init map_lowmem(void)
-- 
1.9.1

^ permalink raw reply related	[flat|nested] 30+ messages in thread
* [PATCH v3 2/7] arm: fixmap: implement __set_fixmap()
  2014-08-12 18:24 ` Kees Cook
@ 2014-08-12 18:24   ` Kees Cook
  -1 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 18:24 UTC (permalink / raw)
  To: linux-kernel
  Cc: Kees Cook, Rabin Vincent, Laura Abbott, Rob Herring,
	Leif Lindholm, Mark Salter, Liu hua, Nikolay Borisov,
	Nicolas Pitre, Tomasz Figa, Doug Anderson, Jason Wessel,
	Will Deacon, Catalin Marinas, Russell King - ARM Linux,
	linux-arm-kernel

This is used from set_fixmap() and clear_fixmap() via asm-generic/fixmap.h.
Also makes sure that the fixmap allocation fits into the expected range.

Based on patch by Rabin Vincent.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Rabin Vincent <rabin@rab.in>
---
 arch/arm/include/asm/fixmap.h |  2 ++
 arch/arm/mm/mmu.c             | 19 +++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index a7add6f9315d..48935cc5004f 100644
--- a/arch/arm/include/asm/fixmap.h
+++ b/arch/arm/include/asm/fixmap.h
@@ -14,6 +14,8 @@ enum fixed_addresses {
 	__end_of_fixed_addresses
 };
 
+void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot);
+
 #include <asm-generic/fixmap.h>
 
 #endif
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 7fa0966cd15f..48ba2b1d7d8e 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -22,6 +22,7 @@
 #include <asm/cputype.h>
 #include <asm/sections.h>
 #include <asm/cachetype.h>
+#include <asm/fixmap.h>
 #include <asm/sections.h>
 #include <asm/setup.h>
 #include <asm/smp_plat.h>
@@ -392,6 +393,24 @@ SET_MEMORY_FN(rw, pte_set_rw)
 SET_MEMORY_FN(x, pte_set_x)
 SET_MEMORY_FN(nx, pte_set_nx)
 
+void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot)
+{
+	unsigned long vaddr = __fix_to_virt(idx);
+	pte_t *pte = pte_offset_kernel(pmd_off_k(FIXADDR_START), vaddr);
+
+	/* Make sure fixmap region does not exceed available allocation. */
+	BUILD_BUG_ON(FIXADDR_START + (__end_of_fixed_addresses * PAGE_SIZE) >
+		     FIXADDR_END);
+	BUG_ON(idx >= __end_of_fixed_addresses);
+
+	if (pgprot_val(prot))
+		set_pte_at(NULL, vaddr, pte,
+			pfn_pte(phys >> PAGE_SHIFT, prot));
+	else
+		pte_clear(NULL, vaddr, pte);
+	flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);
+}
+
 /*
  * Adjust the PMD section entries according to the CPU in use.
  */
-- 
1.9.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread
* [PATCH v3 2/7] arm: fixmap: implement __set_fixmap()
@ 2014-08-12 18:24   ` Kees Cook
  0 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 18:24 UTC (permalink / raw)
  To: linux-arm-kernel

This is used from set_fixmap() and clear_fixmap() via asm-generic/fixmap.h.
Also makes sure that the fixmap allocation fits into the expected range.

Based on patch by Rabin Vincent.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Rabin Vincent <rabin@rab.in>
---
 arch/arm/include/asm/fixmap.h |  2 ++
 arch/arm/mm/mmu.c             | 19 +++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index a7add6f9315d..48935cc5004f 100644
--- a/arch/arm/include/asm/fixmap.h
+++ b/arch/arm/include/asm/fixmap.h
@@ -14,6 +14,8 @@ enum fixed_addresses {
 	__end_of_fixed_addresses
 };
 
+void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot);
+
 #include <asm-generic/fixmap.h>
 
 #endif
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 7fa0966cd15f..48ba2b1d7d8e 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -22,6 +22,7 @@
 #include <asm/cputype.h>
 #include <asm/sections.h>
 #include <asm/cachetype.h>
+#include <asm/fixmap.h>
 #include <asm/sections.h>
 #include <asm/setup.h>
 #include <asm/smp_plat.h>
@@ -392,6 +393,24 @@ SET_MEMORY_FN(rw, pte_set_rw)
 SET_MEMORY_FN(x, pte_set_x)
 SET_MEMORY_FN(nx, pte_set_nx)
 
+void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot)
+{
+	unsigned long vaddr = __fix_to_virt(idx);
+	pte_t *pte = pte_offset_kernel(pmd_off_k(FIXADDR_START), vaddr);
+
+	/* Make sure fixmap region does not exceed available allocation. */
+	BUILD_BUG_ON(FIXADDR_START + (__end_of_fixed_addresses * PAGE_SIZE) >
+		     FIXADDR_END);
+	BUG_ON(idx >= __end_of_fixed_addresses);
+
+	if (pgprot_val(prot))
+		set_pte_at(NULL, vaddr, pte,
+			pfn_pte(phys >> PAGE_SHIFT, prot));
+	else
+		pte_clear(NULL, vaddr, pte);
+	flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);
+}
+
 /*
  * Adjust the PMD section entries according to the CPU in use.
  */
-- 
1.9.1

^ permalink raw reply related	[flat|nested] 30+ messages in thread
* [PATCH v3 3/7] arm: use fixmap for text patching when text is RO
  2014-08-12 18:24 ` Kees Cook
@ 2014-08-12 18:24   ` Kees Cook
  -1 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 18:24 UTC (permalink / raw)
  To: linux-kernel
  Cc: Kees Cook, Rabin Vincent, Laura Abbott, Rob Herring,
	Leif Lindholm, Mark Salter, Liu hua, Nikolay Borisov,
	Nicolas Pitre, Tomasz Figa, Doug Anderson, Jason Wessel,
	Will Deacon, Catalin Marinas, Russell King - ARM Linux,
	linux-arm-kernel

From: Rabin Vincent <rabin@rab.in>

Use fixmaps for text patching when the kernel text is read-only,
inspired by x86.  This makes jump labels and kprobes work with the
currently available CONFIG_DEBUG_SET_MODULE_RONX and the upcoming
CONFIG_DEBUG_RODATA options.

Signed-off-by: Rabin Vincent <rabin@rab.in>
[kees: fixed up for merge with "arm: use generic fixmap.h"]
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 arch/arm/include/asm/fixmap.h |  4 +++
 arch/arm/kernel/jump_label.c  |  2 +-
 arch/arm/kernel/patch.c       | 70 ++++++++++++++++++++++++++++++++++++++-----
 arch/arm/kernel/patch.h       | 12 +++++++-
 4 files changed, 79 insertions(+), 9 deletions(-)

diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index 48935cc5004f..0d5e1b002002 100644
--- a/arch/arm/include/asm/fixmap.h
+++ b/arch/arm/include/asm/fixmap.h
@@ -11,6 +11,10 @@ enum fixed_addresses {
 	FIX_KMAP_BEGIN,
 	FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * NR_CPUS) - 1,
 
+	/* Support writing RO kernel text via kprobes, jump labels, etc. */
+	FIX_TEXT_POKE0,
+	FIX_TEXT_POKE1,
+
 	__end_of_fixed_addresses
 };
 
diff --git a/arch/arm/kernel/jump_label.c b/arch/arm/kernel/jump_label.c
index 4ce4f789446d..afeeb9ea6f43 100644
--- a/arch/arm/kernel/jump_label.c
+++ b/arch/arm/kernel/jump_label.c
@@ -19,7 +19,7 @@ static void __arch_jump_label_transform(struct jump_entry *entry,
 		insn = arm_gen_nop();
 
 	if (is_static)
-		__patch_text(addr, insn);
+		__patch_text_early(addr, insn);
 	else
 		patch_text(addr, insn);
 }
diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
index 07314af47733..03dd4e39c833 100644
--- a/arch/arm/kernel/patch.c
+++ b/arch/arm/kernel/patch.c
@@ -1,8 +1,11 @@
 #include <linux/kernel.h>
+#include <linux/spinlock.h>
 #include <linux/kprobes.h>
+#include <linux/mm.h>
 #include <linux/stop_machine.h>
 
 #include <asm/cacheflush.h>
+#include <asm/fixmap.h>
 #include <asm/smp_plat.h>
 #include <asm/opcodes.h>
 
@@ -13,21 +16,69 @@ struct patch {
 	unsigned int insn;
 };
 
-void __kprobes __patch_text(void *addr, unsigned int insn)
+static DEFINE_SPINLOCK(patch_lock);
+
+static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
+{
+	unsigned int uintaddr = (uintptr_t) addr;
+	bool module = !core_kernel_text(uintaddr);
+	struct page *page;
+
+	if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
+		page = vmalloc_to_page(addr);
+	else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
+		page = virt_to_page(addr);
+	else
+		return addr;
+
+	if (flags)
+		spin_lock_irqsave(&patch_lock, *flags);
+
+	set_fixmap(fixmap, page_to_phys(page));
+
+	return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
+}
+
+static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
+{
+	clear_fixmap(fixmap);
+
+	if (flags)
+		spin_unlock_irqrestore(&patch_lock, *flags);
+}
+
+void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
 {
 	bool thumb2 = IS_ENABLED(CONFIG_THUMB2_KERNEL);
+	unsigned int uintaddr = (uintptr_t) addr;
+	bool twopage = false;
+	unsigned long flags;
+	void *waddr = addr;
 	int size;
 
+	if (remap)
+		waddr = patch_map(addr, FIX_TEXT_POKE0, &flags);
+
 	if (thumb2 && __opcode_is_thumb16(insn)) {
-		*(u16 *)addr = __opcode_to_mem_thumb16(insn);
+		*(u16 *)waddr = __opcode_to_mem_thumb16(insn);
 		size = sizeof(u16);
-	} else if (thumb2 && ((uintptr_t)addr & 2)) {
+	} else if (thumb2 && (uintaddr & 2)) {
 		u16 first = __opcode_thumb32_first(insn);
 		u16 second = __opcode_thumb32_second(insn);
-		u16 *addrh = addr;
+		u16 *addrh0 = waddr;
+		u16 *addrh1 = waddr + 2;
 
-		addrh[0] = __opcode_to_mem_thumb16(first);
-		addrh[1] = __opcode_to_mem_thumb16(second);
+		twopage = (uintaddr & ~PAGE_MASK) == PAGE_SIZE - 2;
+		if (twopage && remap)
+			addrh1 = patch_map(addr + 2, FIX_TEXT_POKE1, NULL);
+
+		*addrh0 = __opcode_to_mem_thumb16(first);
+		*addrh1 = __opcode_to_mem_thumb16(second);
+
+		if (twopage && addrh1 != addr + 2) {
+			flush_kernel_vmap_range(addrh1, 2);
+			patch_unmap(FIX_TEXT_POKE1, NULL);
+		}
 
 		size = sizeof(u32);
 	} else {
@@ -36,10 +87,15 @@ void __kprobes __patch_text(void *addr, unsigned int insn)
 		else
 			insn = __opcode_to_mem_arm(insn);
 
-		*(u32 *)addr = insn;
+		*(u32 *)waddr = insn;
 		size = sizeof(u32);
 	}
 
+	if (waddr != addr) {
+		flush_kernel_vmap_range(waddr, twopage ? size / 2 : size);
+		patch_unmap(FIX_TEXT_POKE0, &flags);
+	}
+
 	flush_icache_range((uintptr_t)(addr),
 			   (uintptr_t)(addr) + size);
 }
diff --git a/arch/arm/kernel/patch.h b/arch/arm/kernel/patch.h
index b4731f2dac38..77e054c2f6cd 100644
--- a/arch/arm/kernel/patch.h
+++ b/arch/arm/kernel/patch.h
@@ -2,6 +2,16 @@
 #define _ARM_KERNEL_PATCH_H
 
 void patch_text(void *addr, unsigned int insn);
-void __patch_text(void *addr, unsigned int insn);
+void __patch_text_real(void *addr, unsigned int insn, bool remap);
+
+static inline void __patch_text(void *addr, unsigned int insn)
+{
+	__patch_text_real(addr, insn, true);
+}
+
+static inline void __patch_text_early(void *addr, unsigned int insn)
+{
+	__patch_text_real(addr, insn, false);
+}
 
 #endif
-- 
1.9.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread
* [PATCH v3 3/7] arm: use fixmap for text patching when text is RO
@ 2014-08-12 18:24   ` Kees Cook
  0 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 18:24 UTC (permalink / raw)
  To: linux-arm-kernel

From: Rabin Vincent <rabin@rab.in>

Use fixmaps for text patching when the kernel text is read-only,
inspired by x86.  This makes jump labels and kprobes work with the
currently available CONFIG_DEBUG_SET_MODULE_RONX and the upcoming
CONFIG_DEBUG_RODATA options.

Signed-off-by: Rabin Vincent <rabin@rab.in>
[kees: fixed up for merge with "arm: use generic fixmap.h"]
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 arch/arm/include/asm/fixmap.h |  4 +++
 arch/arm/kernel/jump_label.c  |  2 +-
 arch/arm/kernel/patch.c       | 70 ++++++++++++++++++++++++++++++++++++++-----
 arch/arm/kernel/patch.h       | 12 +++++++-
 4 files changed, 79 insertions(+), 9 deletions(-)

diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index 48935cc5004f..0d5e1b002002 100644
--- a/arch/arm/include/asm/fixmap.h
+++ b/arch/arm/include/asm/fixmap.h
@@ -11,6 +11,10 @@ enum fixed_addresses {
 	FIX_KMAP_BEGIN,
 	FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * NR_CPUS) - 1,
 
+	/* Support writing RO kernel text via kprobes, jump labels, etc. */
+	FIX_TEXT_POKE0,
+	FIX_TEXT_POKE1,
+
 	__end_of_fixed_addresses
 };
 
diff --git a/arch/arm/kernel/jump_label.c b/arch/arm/kernel/jump_label.c
index 4ce4f789446d..afeeb9ea6f43 100644
--- a/arch/arm/kernel/jump_label.c
+++ b/arch/arm/kernel/jump_label.c
@@ -19,7 +19,7 @@ static void __arch_jump_label_transform(struct jump_entry *entry,
 		insn = arm_gen_nop();
 
 	if (is_static)
-		__patch_text(addr, insn);
+		__patch_text_early(addr, insn);
 	else
 		patch_text(addr, insn);
 }
diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
index 07314af47733..03dd4e39c833 100644
--- a/arch/arm/kernel/patch.c
+++ b/arch/arm/kernel/patch.c
@@ -1,8 +1,11 @@
 #include <linux/kernel.h>
+#include <linux/spinlock.h>
 #include <linux/kprobes.h>
+#include <linux/mm.h>
 #include <linux/stop_machine.h>
 
 #include <asm/cacheflush.h>
+#include <asm/fixmap.h>
 #include <asm/smp_plat.h>
 #include <asm/opcodes.h>
 
@@ -13,21 +16,69 @@ struct patch {
 	unsigned int insn;
 };
 
-void __kprobes __patch_text(void *addr, unsigned int insn)
+static DEFINE_SPINLOCK(patch_lock);
+
+static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
+{
+	unsigned int uintaddr = (uintptr_t) addr;
+	bool module = !core_kernel_text(uintaddr);
+	struct page *page;
+
+	if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
+		page = vmalloc_to_page(addr);
+	else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
+		page = virt_to_page(addr);
+	else
+		return addr;
+
+	if (flags)
+		spin_lock_irqsave(&patch_lock, *flags);
+
+	set_fixmap(fixmap, page_to_phys(page));
+
+	return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
+}
+
+static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
+{
+	clear_fixmap(fixmap);
+
+	if (flags)
+		spin_unlock_irqrestore(&patch_lock, *flags);
+}
+
+void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
 {
 	bool thumb2 = IS_ENABLED(CONFIG_THUMB2_KERNEL);
+	unsigned int uintaddr = (uintptr_t) addr;
+	bool twopage = false;
+	unsigned long flags;
+	void *waddr = addr;
 	int size;
 
+	if (remap)
+		waddr = patch_map(addr, FIX_TEXT_POKE0, &flags);
+
 	if (thumb2 && __opcode_is_thumb16(insn)) {
-		*(u16 *)addr = __opcode_to_mem_thumb16(insn);
+		*(u16 *)waddr = __opcode_to_mem_thumb16(insn);
 		size = sizeof(u16);
-	} else if (thumb2 && ((uintptr_t)addr & 2)) {
+	} else if (thumb2 && (uintaddr & 2)) {
 		u16 first = __opcode_thumb32_first(insn);
 		u16 second = __opcode_thumb32_second(insn);
-		u16 *addrh = addr;
+		u16 *addrh0 = waddr;
+		u16 *addrh1 = waddr + 2;
 
-		addrh[0] = __opcode_to_mem_thumb16(first);
-		addrh[1] = __opcode_to_mem_thumb16(second);
+		twopage = (uintaddr & ~PAGE_MASK) == PAGE_SIZE - 2;
+		if (twopage && remap)
+			addrh1 = patch_map(addr + 2, FIX_TEXT_POKE1, NULL);
+
+		*addrh0 = __opcode_to_mem_thumb16(first);
+		*addrh1 = __opcode_to_mem_thumb16(second);
+
+		if (twopage && addrh1 != addr + 2) {
+			flush_kernel_vmap_range(addrh1, 2);
+			patch_unmap(FIX_TEXT_POKE1, NULL);
+		}
 
 		size = sizeof(u32);
 	} else {
@@ -36,10 +87,15 @@ void __kprobes __patch_text(void *addr, unsigned int insn)
 		else
 			insn = __opcode_to_mem_arm(insn);
 
-		*(u32 *)addr = insn;
+		*(u32 *)waddr = insn;
 		size = sizeof(u32);
 	}
 
+	if (waddr != addr) {
+		flush_kernel_vmap_range(waddr, twopage ? size / 2 : size);
+		patch_unmap(FIX_TEXT_POKE0, &flags);
+	}
+
 	flush_icache_range((uintptr_t)(addr),
 			   (uintptr_t)(addr) + size);
 }
diff --git a/arch/arm/kernel/patch.h b/arch/arm/kernel/patch.h
index b4731f2dac38..77e054c2f6cd 100644
--- a/arch/arm/kernel/patch.h
+++ b/arch/arm/kernel/patch.h
@@ -2,6 +2,16 @@
 #define _ARM_KERNEL_PATCH_H
 
 void patch_text(void *addr, unsigned int insn);
-void __patch_text(void *addr, unsigned int insn);
+void __patch_text_real(void *addr, unsigned int insn, bool remap);
+
+static inline void __patch_text(void *addr, unsigned int insn)
+{
+	__patch_text_real(addr, insn, true);
+}
+
+static inline void __patch_text_early(void *addr, unsigned int insn)
+{
+	__patch_text_real(addr, insn, false);
+}
 
 #endif
-- 
1.9.1

^ permalink raw reply related	[flat|nested] 30+ messages in thread
* [PATCH v3 4/7] ARM: kexec: Make .text R/W in machine_kexec
  2014-08-12 18:24 ` Kees Cook
@ 2014-08-12 18:24   ` Kees Cook
  -1 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 18:24 UTC (permalink / raw)
  To: linux-kernel
  Cc: Kees Cook, Nikolay Borisov, Laura Abbott, Rob Herring,
	Leif Lindholm, Mark Salter, Rabin Vincent, Liu hua,
	Nicolas Pitre, Tomasz Figa, Doug Anderson, Jason Wessel,
	Will Deacon, Catalin Marinas, Russell King - ARM Linux,
	linux-arm-kernel

From: Nikolay Borisov <Nikolay.Borisov@arm.com>

With the introduction of Kees Cook's patch to make the kernel .text
read-only the existing method by which kexec works got broken since it
directly pokes some values in the template code, which resides in the
.text section.

The current patch changes the way those values are inserted so that poking
.text section occurs only in machine_kexec (e.g when we are about to nuke
the old kernel and are beyond the point of return). This allows to use
set_kernel_text_rw() to directly patch the values in the .text section.

I had already sent a patch which achieved this but it was significantly
more complicated, so this is a cleaner/straight-forward approach.

Signed-off-by: Nikolay Borisov <Nikolay.Borisov@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
[kees: collapsed kexec_boot_atags (will.daecon)]
[kees: for bisectability, moved set_kernel_text_rw() to RODATA patch]
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 arch/arm/kernel/machine_kexec.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
index 8cf0996aa1a8..8f75250cbe30 100644
--- a/arch/arm/kernel/machine_kexec.c
+++ b/arch/arm/kernel/machine_kexec.c
@@ -29,6 +29,7 @@ extern unsigned long kexec_boot_atags;
 
 static atomic_t waiting_for_crash_ipi;
 
+static unsigned long dt_mem;
 /*
  * Provide a dummy crash_notes definition while crash dump arrives to arm.
  * This prevents breakage of crash_notes attribute in kernel/ksysfs.c.
@@ -64,7 +65,7 @@ int machine_kexec_prepare(struct kimage *image)
 			return err;
 
 		if (be32_to_cpu(header) == OF_DT_HEADER)
-			kexec_boot_atags = current_segment->mem;
+			dt_mem = current_segment->mem;
 	}
 	return 0;
 }
@@ -166,9 +167,8 @@ void machine_kexec(struct kimage *image)
 	kexec_start_address = image->start;
 	kexec_indirection_page = page_list;
 	kexec_mach_type = machine_arch_type;
-	if (!kexec_boot_atags)
-		kexec_boot_atags = image->start - KEXEC_ARM_ZIMAGE_OFFSET + KEXEC_ARM_ATAGS_OFFSET;
-
+	kexec_boot_atags = dt_mem ?: image->start - KEXEC_ARM_ZIMAGE_OFFSET
+				     + KEXEC_ARM_ATAGS_OFFSET;
 
 	/* copy our kernel relocation code to the control code page */
 	reboot_entry = fncpy(reboot_code_buffer,
-- 
1.9.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread
* [PATCH v3 4/7] ARM: kexec: Make .text R/W in machine_kexec
@ 2014-08-12 18:24   ` Kees Cook
  0 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 18:24 UTC (permalink / raw)
  To: linux-arm-kernel

From: Nikolay Borisov <Nikolay.Borisov@arm.com>

With the introduction of Kees Cook's patch to make the kernel .text
read-only the existing method by which kexec works got broken since it
directly pokes some values in the template code, which resides in the
.text section.

The current patch changes the way those values are inserted so that poking
.text section occurs only in machine_kexec (e.g when we are about to nuke
the old kernel and are beyond the point of return). This allows to use
set_kernel_text_rw() to directly patch the values in the .text section.

I had already sent a patch which achieved this but it was significantly
more complicated, so this is a cleaner/straight-forward approach.

Signed-off-by: Nikolay Borisov <Nikolay.Borisov@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
[kees: collapsed kexec_boot_atags (will.daecon)]
[kees: for bisectability, moved set_kernel_text_rw() to RODATA patch]
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 arch/arm/kernel/machine_kexec.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
index 8cf0996aa1a8..8f75250cbe30 100644
--- a/arch/arm/kernel/machine_kexec.c
+++ b/arch/arm/kernel/machine_kexec.c
@@ -29,6 +29,7 @@ extern unsigned long kexec_boot_atags;
 
 static atomic_t waiting_for_crash_ipi;
 
+static unsigned long dt_mem;
 /*
  * Provide a dummy crash_notes definition while crash dump arrives to arm.
  * This prevents breakage of crash_notes attribute in kernel/ksysfs.c.
@@ -64,7 +65,7 @@ int machine_kexec_prepare(struct kimage *image)
 			return err;
 
 		if (be32_to_cpu(header) == OF_DT_HEADER)
-			kexec_boot_atags = current_segment->mem;
+			dt_mem = current_segment->mem;
 	}
 	return 0;
 }
@@ -166,9 +167,8 @@ void machine_kexec(struct kimage *image)
 	kexec_start_address = image->start;
 	kexec_indirection_page = page_list;
 	kexec_mach_type = machine_arch_type;
-	if (!kexec_boot_atags)
-		kexec_boot_atags = image->start - KEXEC_ARM_ZIMAGE_OFFSET + KEXEC_ARM_ATAGS_OFFSET;
-
+	kexec_boot_atags = dt_mem ?: image->start - KEXEC_ARM_ZIMAGE_OFFSET
+				     + KEXEC_ARM_ATAGS_OFFSET;
 
 	/* copy our kernel relocation code to the control code page */
 	reboot_entry = fncpy(reboot_code_buffer,
-- 
1.9.1

^ permalink raw reply related	[flat|nested] 30+ messages in thread
* [PATCH v3 5/7] arm: kgdb: Handle read-only text / modules
  2014-08-12 18:24 ` Kees Cook
@ 2014-08-12 18:24   ` Kees Cook
  -1 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 18:24 UTC (permalink / raw)
  To: linux-kernel
  Cc: Kees Cook, Doug Anderson, Laura Abbott, Rob Herring,
	Leif Lindholm, Mark Salter, Rabin Vincent, Liu hua,
	Nikolay Borisov, Nicolas Pitre, Tomasz Figa, Doug Anderson,
	Jason Wessel, Will Deacon, Catalin Marinas,
	Russell King - ARM Linux, linux-arm-kernel

From: Doug Anderson <dianders@chromium.org>

Handle the case where someone has set the text segment of the kernel
as read-only by using the newly introduced "patch" mechanism.

Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 arch/arm/kernel/Makefile |  2 +-
 arch/arm/kernel/kgdb.c   | 30 ++++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 38ddd9f83d0e..70b730766330 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -67,7 +67,7 @@ test-kprobes-objs		+= kprobes-test-arm.o
 endif
 obj-$(CONFIG_OABI_COMPAT)	+= sys_oabi-compat.o
 obj-$(CONFIG_ARM_THUMBEE)	+= thumbee.o
-obj-$(CONFIG_KGDB)		+= kgdb.o
+obj-$(CONFIG_KGDB)		+= kgdb.o patch.o
 obj-$(CONFIG_ARM_UNWIND)	+= unwind.o
 obj-$(CONFIG_HAVE_TCM)		+= tcm.o
 obj-$(CONFIG_OF)		+= devtree.o
diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c
index a74b53c1b7df..b2b9ccb6be59 100644
--- a/arch/arm/kernel/kgdb.c
+++ b/arch/arm/kernel/kgdb.c
@@ -12,8 +12,12 @@
 #include <linux/irq.h>
 #include <linux/kdebug.h>
 #include <linux/kgdb.h>
+#include <linux/uaccess.h>
+
 #include <asm/traps.h>
 
+#include "patch.h"
+
 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
 {
 	{ "r0", 4, offsetof(struct pt_regs, ARM_r0)},
@@ -244,6 +248,32 @@ void kgdb_arch_exit(void)
 	unregister_die_notifier(&kgdb_notifier);
 }
 
+int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
+{
+	int err;
+
+	/* patch_text() only supports int-sized breakpoints */
+	if (sizeof(int) != BREAK_INSTR_SIZE)
+		return -EINVAL;
+
+	err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
+				BREAK_INSTR_SIZE);
+	if (err)
+		return err;
+
+	patch_text((void *)bpt->bpt_addr,
+		   *(unsigned int *)arch_kgdb_ops.gdb_bpt_instr);
+
+	return err;
+}
+
+int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
+{
+	patch_text((void *)bpt->bpt_addr, *(unsigned int *)bpt->saved_instr);
+
+	return 0;
+}
+
 /*
  * Register our undef instruction hooks with ARM undef core.
  * We regsiter a hook specifically looking for the KGB break inst
-- 
1.9.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread
* [PATCH v3 5/7] arm: kgdb: Handle read-only text / modules
@ 2014-08-12 18:24   ` Kees Cook
  0 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 18:24 UTC (permalink / raw)
  To: linux-arm-kernel

From: Doug Anderson <dianders@chromium.org>

Handle the case where someone has set the text segment of the kernel
as read-only by using the newly introduced "patch" mechanism.

Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 arch/arm/kernel/Makefile |  2 +-
 arch/arm/kernel/kgdb.c   | 30 ++++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 38ddd9f83d0e..70b730766330 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -67,7 +67,7 @@ test-kprobes-objs		+= kprobes-test-arm.o
 endif
 obj-$(CONFIG_OABI_COMPAT)	+= sys_oabi-compat.o
 obj-$(CONFIG_ARM_THUMBEE)	+= thumbee.o
-obj-$(CONFIG_KGDB)		+= kgdb.o
+obj-$(CONFIG_KGDB)		+= kgdb.o patch.o
 obj-$(CONFIG_ARM_UNWIND)	+= unwind.o
 obj-$(CONFIG_HAVE_TCM)		+= tcm.o
 obj-$(CONFIG_OF)		+= devtree.o
diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c
index a74b53c1b7df..b2b9ccb6be59 100644
--- a/arch/arm/kernel/kgdb.c
+++ b/arch/arm/kernel/kgdb.c
@@ -12,8 +12,12 @@
 #include <linux/irq.h>
 #include <linux/kdebug.h>
 #include <linux/kgdb.h>
+#include <linux/uaccess.h>
+
 #include <asm/traps.h>
 
+#include "patch.h"
+
 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
 {
 	{ "r0", 4, offsetof(struct pt_regs, ARM_r0)},
@@ -244,6 +248,32 @@ void kgdb_arch_exit(void)
 	unregister_die_notifier(&kgdb_notifier);
 }
 
+int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
+{
+	int err;
+
+	/* patch_text() only supports int-sized breakpoints */
+	if (sizeof(int) != BREAK_INSTR_SIZE)
+		return -EINVAL;
+
+	err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
+				BREAK_INSTR_SIZE);
+	if (err)
+		return err;
+
+	patch_text((void *)bpt->bpt_addr,
+		   *(unsigned int *)arch_kgdb_ops.gdb_bpt_instr);
+
+	return err;
+}
+
+int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
+{
+	patch_text((void *)bpt->bpt_addr, *(unsigned int *)bpt->saved_instr);
+
+	return 0;
+}
+
 /*
  * Register our undef instruction hooks with ARM undef core.
  * We regsiter a hook specifically looking for the KGB break inst
-- 
1.9.1

^ permalink raw reply related	[flat|nested] 30+ messages in thread
* [PATCH v3 6/7] ARM: mm: allow non-text sections to be non-executable
  2014-08-12 18:24 ` Kees Cook
@ 2014-08-12 18:24   ` Kees Cook
  -1 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 18:24 UTC (permalink / raw)
  To: linux-kernel
  Cc: Kees Cook, Laura Abbott, Rob Herring, Leif Lindholm, Mark Salter,
	Rabin Vincent, Liu hua, Nikolay Borisov, Nicolas Pitre,
	Tomasz Figa, Doug Anderson, Jason Wessel, Will Deacon,
	Catalin Marinas, Russell King - ARM Linux, linux-arm-kernel

Adds CONFIG_ARM_KERNMEM_PERMS to separate the kernel memory regions
into section-sized areas that can have different permisions. Performs
the NX permission changes during free_initmem, so that init memory can be
reclaimed.

This uses section size instead of PMD size to reduce memory lost to
padding on non-LPAE systems.

Based on work by Brad Spengler, Larry Bassel, and Laura Abbott.

Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Laura Abbott <lauraa@codeaurora.org>
---
 arch/arm/kernel/vmlinux.lds.S |  17 +++++++
 arch/arm/mm/Kconfig           |   9 ++++
 arch/arm/mm/init.c            | 106 ++++++++++++++++++++++++++++++++++++++++++
 arch/arm/mm/mmu.c             |  13 +++++-
 4 files changed, 144 insertions(+), 1 deletion(-)

diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index 6f57cb94367f..a3d07ca2bbb4 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -8,6 +8,9 @@
 #include <asm/thread_info.h>
 #include <asm/memory.h>
 #include <asm/page.h>
+#ifdef CONFIG_ARM_KERNMEM_PERMS
+#include <asm/pgtable.h>
+#endif
 	
 #define PROC_INFO							\
 	. = ALIGN(4);							\
@@ -90,6 +93,11 @@ SECTIONS
 		_text = .;
 		HEAD_TEXT
 	}
+
+#ifdef CONFIG_ARM_KERNMEM_PERMS
+	. = ALIGN(1<<SECTION_SHIFT);
+#endif
+
 	.text : {			/* Real text segment		*/
 		_stext = .;		/* Text and read-only data	*/
 			__exception_text_start = .;
@@ -145,7 +153,11 @@ SECTIONS
 	_etext = .;			/* End of text and rodata section */
 
 #ifndef CONFIG_XIP_KERNEL
+# ifdef CONFIG_ARM_KERNMEM_PERMS
+	. = ALIGN(1<<SECTION_SHIFT);
+# else
 	. = ALIGN(PAGE_SIZE);
+# endif
 	__init_begin = .;
 #endif
 	/*
@@ -220,7 +232,12 @@ SECTIONS
 	. = PAGE_OFFSET + TEXT_OFFSET;
 #else
 	__init_end = .;
+
+#ifdef CONFIG_ARM_KERNMEM_PERMS
+	. = ALIGN(1<<SECTION_SHIFT);
+#else
 	. = ALIGN(THREAD_SIZE);
+#endif
 	__data_loc = .;
 #endif
 
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index ae69809a9e47..7a0756df91a2 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -1008,3 +1008,12 @@ config ARCH_SUPPORTS_BIG_ENDIAN
 	help
 	  This option specifies the architecture can support big endian
 	  operation.
+
+config ARM_KERNMEM_PERMS
+	bool "Restrict kernel memory permissions"
+	help
+	  If this is set, kernel memory other than kernel text (and rodata)
+	  will be made non-executable. The tradeoff is that each region is
+	  padded to section-size (1MiB) boundaries (because their permissions
+	  are different and splitting the 1M pages into 4K ones causes TLB
+	  performance problems), wasting memory.
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index ad82c05bfc3a..ccf392ef40d4 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -32,6 +32,11 @@
 #include <asm/tlb.h>
 #include <asm/fixmap.h>
 
+#ifdef CONFIG_ARM_KERNMEM_PERMS
+#include <asm/system_info.h>
+#include <asm/cp15.h>
+#endif
+
 #include <asm/mach/arch.h>
 #include <asm/mach/map.h>
 
@@ -615,11 +620,112 @@ void __init mem_init(void)
 	}
 }
 
+#ifdef CONFIG_ARM_KERNMEM_PERMS
+struct section_perm {
+	unsigned long start;
+	unsigned long end;
+	pmdval_t mask;
+	pmdval_t prot;
+};
+
+struct section_perm nx_perms[] = {
+	/* Make pages tables, etc before _stext RW (set NX). */
+	{
+		.start	= PAGE_OFFSET,
+		.end	= (unsigned long)_stext,
+		.mask	= ~PMD_SECT_XN,
+		.prot	= PMD_SECT_XN,
+	},
+	/* Make init RW (set NX). */
+	{
+		.start	= (unsigned long)__init_begin,
+		.end	= (unsigned long)_sdata,
+		.mask	= ~PMD_SECT_XN,
+		.prot	= PMD_SECT_XN,
+	},
+};
+
+/*
+ * Updates section permissions only for the current mm (sections are
+ * copied into each mm). During startup, this is the init_mm.
+ */
+static inline void section_update(unsigned long addr, pmdval_t mask,
+				  pmdval_t prot)
+{
+	struct mm_struct *mm;
+	pmd_t *pmd;
+
+	mm = current->active_mm;
+	pmd = pmd_offset(pud_offset(pgd_offset(mm, addr), addr), addr);
+
+#ifdef CONFIG_ARM_LPAE
+	pmd[0] = __pmd((pmd_val(pmd[0]) & mask) | prot);
+#else
+	if (addr & SECTION_SIZE)
+		pmd[1] = __pmd((pmd_val(pmd[1]) & mask) | prot);
+	else
+		pmd[0] = __pmd((pmd_val(pmd[0]) & mask) | prot);
+#endif
+	flush_pmd_entry(pmd);
+	local_flush_tlb_kernel_range(addr, addr + SECTION_SIZE);
+}
+
+/* Make sure extended page tables are in use. */
+static inline bool arch_has_strict_perms(void)
+{
+	unsigned int cr;
+
+	if (cpu_architecture() < CPU_ARCH_ARMv6)
+		return false;
+
+	cr = get_cr();
+	if (!(cr & CR_XP))
+		return false;
+
+	return true;
+}
+
+#define set_section_perms(perms, field)	{				\
+	size_t i;							\
+	unsigned long addr;						\
+									\
+	if (!arch_has_strict_perms())					\
+		return;							\
+									\
+	for (i = 0; i < ARRAY_SIZE(perms); i++) {			\
+		if (!IS_ALIGNED(perms[i].start, SECTION_SIZE) ||	\
+		    !IS_ALIGNED(perms[i].end, SECTION_SIZE)) {		\
+			pr_err("BUG: section %lx-%lx not aligned to %lx\n", \
+				perms[i].start, perms[i].end,		\
+				SECTION_SIZE);				\
+			continue;					\
+		}							\
+									\
+		for (addr = perms[i].start;				\
+		     addr < perms[i].end;				\
+		     addr += SECTION_SIZE)				\
+			section_update(addr, perms[i].mask,		\
+				       perms[i].field);			\
+	}								\
+}
+
+static inline void fix_kernmem_perms(void)
+{
+	set_section_perms(nx_perms, prot);
+}
+#else
+static inline void fix_kernmem_perms(void) { }
+#endif /* CONFIG_ARM_KERNMEM_PERMS */
+
 void free_initmem(void)
 {
 #ifdef CONFIG_HAVE_TCM
 	extern char __tcm_start, __tcm_end;
+#endif
+
+	fix_kernmem_perms();
 
+#ifdef CONFIG_HAVE_TCM
 	poison_init_mem(&__tcm_start, &__tcm_end - &__tcm_start);
 	free_reserved_area(&__tcm_start, &__tcm_end, -1, "TCM link");
 #endif
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 48ba2b1d7d8e..b830a2dc590d 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -1368,13 +1368,24 @@ static void __init map_lowmem(void)
 		if (start >= end)
 			break;
 
-		if (end < kernel_x_start || start >= kernel_x_end) {
+		if (end < kernel_x_start) {
 			map.pfn = __phys_to_pfn(start);
 			map.virtual = __phys_to_virt(start);
 			map.length = end - start;
 			map.type = MT_MEMORY_RWX;
 
 			create_mapping(&map);
+		} else if (start >= kernel_x_end) {
+			map.pfn = __phys_to_pfn(start);
+			map.virtual = __phys_to_virt(start);
+			map.length = end - start;
+#ifdef CONFIG_ARM_KERNMEM_PERMS
+			map.type = MT_MEMORY_RW;
+#else
+			map.type = MT_MEMORY_RWX;
+#endif
+
+			create_mapping(&map);
 		} else {
 			/* This better cover the entire kernel */
 			if (start < kernel_x_start) {
-- 
1.9.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread
* [PATCH v3 6/7] ARM: mm: allow non-text sections to be non-executable
@ 2014-08-12 18:24   ` Kees Cook
  0 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 18:24 UTC (permalink / raw)
  To: linux-arm-kernel

Adds CONFIG_ARM_KERNMEM_PERMS to separate the kernel memory regions
into section-sized areas that can have different permisions. Performs
the NX permission changes during free_initmem, so that init memory can be
reclaimed.

This uses section size instead of PMD size to reduce memory lost to
padding on non-LPAE systems.

Based on work by Brad Spengler, Larry Bassel, and Laura Abbott.

Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Laura Abbott <lauraa@codeaurora.org>
---
 arch/arm/kernel/vmlinux.lds.S |  17 +++++++
 arch/arm/mm/Kconfig           |   9 ++++
 arch/arm/mm/init.c            | 106 ++++++++++++++++++++++++++++++++++++++++++
 arch/arm/mm/mmu.c             |  13 +++++-
 4 files changed, 144 insertions(+), 1 deletion(-)

diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index 6f57cb94367f..a3d07ca2bbb4 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -8,6 +8,9 @@
 #include <asm/thread_info.h>
 #include <asm/memory.h>
 #include <asm/page.h>
+#ifdef CONFIG_ARM_KERNMEM_PERMS
+#include <asm/pgtable.h>
+#endif
 	
 #define PROC_INFO							\
 	. = ALIGN(4);							\
@@ -90,6 +93,11 @@ SECTIONS
 		_text = .;
 		HEAD_TEXT
 	}
+
+#ifdef CONFIG_ARM_KERNMEM_PERMS
+	. = ALIGN(1<<SECTION_SHIFT);
+#endif
+
 	.text : {			/* Real text segment		*/
 		_stext = .;		/* Text and read-only data	*/
 			__exception_text_start = .;
@@ -145,7 +153,11 @@ SECTIONS
 	_etext = .;			/* End of text and rodata section */
 
 #ifndef CONFIG_XIP_KERNEL
+# ifdef CONFIG_ARM_KERNMEM_PERMS
+	. = ALIGN(1<<SECTION_SHIFT);
+# else
 	. = ALIGN(PAGE_SIZE);
+# endif
 	__init_begin = .;
 #endif
 	/*
@@ -220,7 +232,12 @@ SECTIONS
 	. = PAGE_OFFSET + TEXT_OFFSET;
 #else
 	__init_end = .;
+
+#ifdef CONFIG_ARM_KERNMEM_PERMS
+	. = ALIGN(1<<SECTION_SHIFT);
+#else
 	. = ALIGN(THREAD_SIZE);
+#endif
 	__data_loc = .;
 #endif
 
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index ae69809a9e47..7a0756df91a2 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -1008,3 +1008,12 @@ config ARCH_SUPPORTS_BIG_ENDIAN
 	help
 	  This option specifies the architecture can support big endian
 	  operation.
+
+config ARM_KERNMEM_PERMS
+	bool "Restrict kernel memory permissions"
+	help
+	  If this is set, kernel memory other than kernel text (and rodata)
+	  will be made non-executable. The tradeoff is that each region is
+	  padded to section-size (1MiB) boundaries (because their permissions
+	  are different and splitting the 1M pages into 4K ones causes TLB
+	  performance problems), wasting memory.
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index ad82c05bfc3a..ccf392ef40d4 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -32,6 +32,11 @@
 #include <asm/tlb.h>
 #include <asm/fixmap.h>
 
+#ifdef CONFIG_ARM_KERNMEM_PERMS
+#include <asm/system_info.h>
+#include <asm/cp15.h>
+#endif
+
 #include <asm/mach/arch.h>
 #include <asm/mach/map.h>
 
@@ -615,11 +620,112 @@ void __init mem_init(void)
 	}
 }
 
+#ifdef CONFIG_ARM_KERNMEM_PERMS
+struct section_perm {
+	unsigned long start;
+	unsigned long end;
+	pmdval_t mask;
+	pmdval_t prot;
+};
+
+struct section_perm nx_perms[] = {
+	/* Make pages tables, etc before _stext RW (set NX). */
+	{
+		.start	= PAGE_OFFSET,
+		.end	= (unsigned long)_stext,
+		.mask	= ~PMD_SECT_XN,
+		.prot	= PMD_SECT_XN,
+	},
+	/* Make init RW (set NX). */
+	{
+		.start	= (unsigned long)__init_begin,
+		.end	= (unsigned long)_sdata,
+		.mask	= ~PMD_SECT_XN,
+		.prot	= PMD_SECT_XN,
+	},
+};
+
+/*
+ * Updates section permissions only for the current mm (sections are
+ * copied into each mm). During startup, this is the init_mm.
+ */
+static inline void section_update(unsigned long addr, pmdval_t mask,
+				  pmdval_t prot)
+{
+	struct mm_struct *mm;
+	pmd_t *pmd;
+
+	mm = current->active_mm;
+	pmd = pmd_offset(pud_offset(pgd_offset(mm, addr), addr), addr);
+
+#ifdef CONFIG_ARM_LPAE
+	pmd[0] = __pmd((pmd_val(pmd[0]) & mask) | prot);
+#else
+	if (addr & SECTION_SIZE)
+		pmd[1] = __pmd((pmd_val(pmd[1]) & mask) | prot);
+	else
+		pmd[0] = __pmd((pmd_val(pmd[0]) & mask) | prot);
+#endif
+	flush_pmd_entry(pmd);
+	local_flush_tlb_kernel_range(addr, addr + SECTION_SIZE);
+}
+
+/* Make sure extended page tables are in use. */
+static inline bool arch_has_strict_perms(void)
+{
+	unsigned int cr;
+
+	if (cpu_architecture() < CPU_ARCH_ARMv6)
+		return false;
+
+	cr = get_cr();
+	if (!(cr & CR_XP))
+		return false;
+
+	return true;
+}
+
+#define set_section_perms(perms, field)	{				\
+	size_t i;							\
+	unsigned long addr;						\
+									\
+	if (!arch_has_strict_perms())					\
+		return;							\
+									\
+	for (i = 0; i < ARRAY_SIZE(perms); i++) {			\
+		if (!IS_ALIGNED(perms[i].start, SECTION_SIZE) ||	\
+		    !IS_ALIGNED(perms[i].end, SECTION_SIZE)) {		\
+			pr_err("BUG: section %lx-%lx not aligned to %lx\n", \
+				perms[i].start, perms[i].end,		\
+				SECTION_SIZE);				\
+			continue;					\
+		}							\
+									\
+		for (addr = perms[i].start;				\
+		     addr < perms[i].end;				\
+		     addr += SECTION_SIZE)				\
+			section_update(addr, perms[i].mask,		\
+				       perms[i].field);			\
+	}								\
+}
+
+static inline void fix_kernmem_perms(void)
+{
+	set_section_perms(nx_perms, prot);
+}
+#else
+static inline void fix_kernmem_perms(void) { }
+#endif /* CONFIG_ARM_KERNMEM_PERMS */
+
 void free_initmem(void)
 {
 #ifdef CONFIG_HAVE_TCM
 	extern char __tcm_start, __tcm_end;
+#endif
+
+	fix_kernmem_perms();
 
+#ifdef CONFIG_HAVE_TCM
 	poison_init_mem(&__tcm_start, &__tcm_end - &__tcm_start);
 	free_reserved_area(&__tcm_start, &__tcm_end, -1, "TCM link");
 #endif
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 48ba2b1d7d8e..b830a2dc590d 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -1368,13 +1368,24 @@ static void __init map_lowmem(void)
 		if (start >= end)
 			break;
 
-		if (end < kernel_x_start || start >= kernel_x_end) {
+		if (end < kernel_x_start) {
 			map.pfn = __phys_to_pfn(start);
 			map.virtual = __phys_to_virt(start);
 			map.length = end - start;
 			map.type = MT_MEMORY_RWX;
 
 			create_mapping(&map);
+		} else if (start >= kernel_x_end) {
+			map.pfn = __phys_to_pfn(start);
+			map.virtual = __phys_to_virt(start);
+			map.length = end - start;
+#ifdef CONFIG_ARM_KERNMEM_PERMS
+			map.type = MT_MEMORY_RW;
+#else
+			map.type = MT_MEMORY_RWX;
+#endif
+
+			create_mapping(&map);
 		} else {
 			/* This better cover the entire kernel */
 			if (start < kernel_x_start) {
-- 
1.9.1

^ permalink raw reply related	[flat|nested] 30+ messages in thread
* [PATCH v3 7/7] ARM: mm: allow text and rodata sections to be read-only
  2014-08-12 18:24 ` Kees Cook
@ 2014-08-12 18:24   ` Kees Cook
  -1 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 18:24 UTC (permalink / raw)
  To: linux-kernel
  Cc: Kees Cook, Laura Abbott, Rob Herring, Leif Lindholm, Mark Salter,
	Rabin Vincent, Liu hua, Nikolay Borisov, Nicolas Pitre,
	Tomasz Figa, Doug Anderson, Jason Wessel, Will Deacon,
	Catalin Marinas, Russell King - ARM Linux, linux-arm-kernel

This introduces CONFIG_DEBUG_RODATA, making kernel text and rodata
read-only. Additionally, this splits rodata from text so that rodata can
also be NX, which may lead to wasted memory when aligning to SECTION_SIZE.
The read-only areas are made writable during ftrace updates and kexec.

Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Laura Abbott <lauraa@codeaurora.org>
---
 arch/arm/include/asm/cacheflush.h | 10 +++++++++
 arch/arm/kernel/ftrace.c          | 19 ++++++++++++++++
 arch/arm/kernel/machine_kexec.c   |  1 +
 arch/arm/kernel/vmlinux.lds.S     |  3 +++
 arch/arm/mm/Kconfig               | 12 ++++++++++
 arch/arm/mm/init.c                | 46 +++++++++++++++++++++++++++++++++++++++
 6 files changed, 91 insertions(+)

diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h
index fd43f7f55b70..0cdf1e31df86 100644
--- a/arch/arm/include/asm/cacheflush.h
+++ b/arch/arm/include/asm/cacheflush.h
@@ -487,6 +487,16 @@ int set_memory_rw(unsigned long addr, int numpages);
 int set_memory_x(unsigned long addr, int numpages);
 int set_memory_nx(unsigned long addr, int numpages);
 
+#ifdef CONFIG_DEBUG_RODATA
+void mark_rodata_ro(void);
+void set_kernel_text_rw(void);
+void set_kernel_text_ro(void);
+#else
+static inline void set_kernel_text_rw(void) { }
+static inline void set_kernel_text_ro(void) { }
+#endif
+
 void flush_uprobe_xol_access(struct page *page, unsigned long uaddr,
 			     void *kaddr, unsigned long len);
+
 #endif
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index af9a8a927a4e..b8c75e45a950 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -15,6 +15,7 @@
 #include <linux/ftrace.h>
 #include <linux/uaccess.h>
 #include <linux/module.h>
+#include <linux/stop_machine.h>
 
 #include <asm/cacheflush.h>
 #include <asm/opcodes.h>
@@ -35,6 +36,22 @@
 
 #define	OLD_NOP		0xe1a00000	/* mov r0, r0 */
 
+static int __ftrace_modify_code(void *data)
+{
+	int *command = data;
+
+	set_kernel_text_rw();
+	ftrace_modify_all_code(*command);
+	set_kernel_text_ro();
+
+	return 0;
+}
+
+void arch_ftrace_update_code(int command)
+{
+	stop_machine(__ftrace_modify_code, &command, NULL);
+}
+
 static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
 {
 	return rec->arch.old_mcount ? OLD_NOP : NOP;
@@ -73,6 +90,8 @@ int ftrace_arch_code_modify_prepare(void)
 int ftrace_arch_code_modify_post_process(void)
 {
 	set_all_modules_text_ro();
+	/* Make sure any TLB misses during machine stop are cleared. */
+	flush_tlb_all();
 	return 0;
 }
 
diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
index 8f75250cbe30..4423a565ef6f 100644
--- a/arch/arm/kernel/machine_kexec.c
+++ b/arch/arm/kernel/machine_kexec.c
@@ -164,6 +164,7 @@ void machine_kexec(struct kimage *image)
 	reboot_code_buffer = page_address(image->control_code_page);
 
 	/* Prepare parameters for reboot_code_buffer*/
+	set_kernel_text_rw();
 	kexec_start_address = image->start;
 	kexec_indirection_page = page_list;
 	kexec_mach_type = machine_arch_type;
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index a3d07ca2bbb4..542e58919bd9 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -120,6 +120,9 @@ SECTIONS
 			ARM_CPU_KEEP(PROC_INFO)
 	}
 
+#ifdef CONFIG_DEBUG_RODATA
+	. = ALIGN(1<<SECTION_SHIFT);
+#endif
 	RO_DATA(PAGE_SIZE)
 
 	. = ALIGN(4);
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index 7a0756df91a2..c9cd9c5bf1e1 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -1017,3 +1017,15 @@ config ARM_KERNMEM_PERMS
 	  padded to section-size (1MiB) boundaries (because their permissions
 	  are different and splitting the 1M pages into 4K ones causes TLB
 	  performance problems), wasting memory.
+
+config DEBUG_RODATA
+	bool "Make kernel text and rodata read-only"
+	depends on ARM_KERNMEM_PERMS
+	default y
+	help
+	  If this is set, kernel text and rodata will be made read-only. This
+	  is to help catch accidental or malicious attempts to change the
+	  kernel's executable code. Additionally splits rodata from kernel
+	  text so it can be made explicitly non-executable. This creates
+	  another section-size padded region, so it can waste more memory
+	  space while gaining the read-only protections.
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index ccf392ef40d4..1a0248a9cfdb 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -626,6 +626,7 @@ struct section_perm {
 	unsigned long end;
 	pmdval_t mask;
 	pmdval_t prot;
+	pmdval_t clear;
 };
 
 struct section_perm nx_perms[] = {
@@ -643,8 +644,35 @@ struct section_perm nx_perms[] = {
 		.mask	= ~PMD_SECT_XN,
 		.prot	= PMD_SECT_XN,
 	},
+#ifdef CONFIG_DEBUG_RODATA
+	/* Make rodata NX (set RO in ro_perms below). */
+	{
+		.start  = (unsigned long)__start_rodata,
+		.end    = (unsigned long)__init_begin,
+		.mask   = ~PMD_SECT_XN,
+		.prot   = PMD_SECT_XN,
+	},
+#endif
 };
 
+#ifdef CONFIG_DEBUG_RODATA
+struct section_perm ro_perms[] = {
+	/* Make kernel code and rodata RX (set RO). */
+	{
+		.start  = (unsigned long)_stext,
+		.end    = (unsigned long)__init_begin,
+#ifdef CONFIG_ARM_LPAE
+		.mask   = ~PMD_SECT_RDONLY,
+		.prot   = PMD_SECT_RDONLY,
+#else
+		.mask   = ~(PMD_SECT_APX | PMD_SECT_AP_WRITE),
+		.prot   = PMD_SECT_APX | PMD_SECT_AP_WRITE,
+		.clear  = PMD_SECT_AP_WRITE,
+#endif
+	},
+};
+#endif
+
 /*
  * Updates section permissions only for the current mm (sections are
  * copied into each mm). During startup, this is the init_mm.
@@ -713,6 +741,24 @@ static inline void fix_kernmem_perms(void)
 {
 	set_section_perms(nx_perms, prot);
 }
+
+#ifdef CONFIG_DEBUG_RODATA
+void mark_rodata_ro(void)
+{
+	set_section_perms(ro_perms, prot);
+}
+
+void set_kernel_text_rw(void)
+{
+	set_section_perms(ro_perms, clear);
+}
+
+void set_kernel_text_ro(void)
+{
+	set_section_perms(ro_perms, prot);
+}
+#endif /* CONFIG_DEBUG_RODATA */
+
 #else
 static inline void fix_kernmem_perms(void) { }
 #endif /* CONFIG_ARM_KERNMEM_PERMS */
-- 
1.9.1


^ permalink raw reply related	[flat|nested] 30+ messages in thread
* [PATCH v3 7/7] ARM: mm: allow text and rodata sections to be read-only
@ 2014-08-12 18:24   ` Kees Cook
  0 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 18:24 UTC (permalink / raw)
  To: linux-arm-kernel

This introduces CONFIG_DEBUG_RODATA, making kernel text and rodata
read-only. Additionally, this splits rodata from text so that rodata can
also be NX, which may lead to wasted memory when aligning to SECTION_SIZE.
The read-only areas are made writable during ftrace updates and kexec.

Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Laura Abbott <lauraa@codeaurora.org>
---
 arch/arm/include/asm/cacheflush.h | 10 +++++++++
 arch/arm/kernel/ftrace.c          | 19 ++++++++++++++++
 arch/arm/kernel/machine_kexec.c   |  1 +
 arch/arm/kernel/vmlinux.lds.S     |  3 +++
 arch/arm/mm/Kconfig               | 12 ++++++++++
 arch/arm/mm/init.c                | 46 +++++++++++++++++++++++++++++++++++++++
 6 files changed, 91 insertions(+)

diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h
index fd43f7f55b70..0cdf1e31df86 100644
--- a/arch/arm/include/asm/cacheflush.h
+++ b/arch/arm/include/asm/cacheflush.h
@@ -487,6 +487,16 @@ int set_memory_rw(unsigned long addr, int numpages);
 int set_memory_x(unsigned long addr, int numpages);
 int set_memory_nx(unsigned long addr, int numpages);
 
+#ifdef CONFIG_DEBUG_RODATA
+void mark_rodata_ro(void);
+void set_kernel_text_rw(void);
+void set_kernel_text_ro(void);
+#else
+static inline void set_kernel_text_rw(void) { }
+static inline void set_kernel_text_ro(void) { }
+#endif
+
 void flush_uprobe_xol_access(struct page *page, unsigned long uaddr,
 			     void *kaddr, unsigned long len);
+
 #endif
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index af9a8a927a4e..b8c75e45a950 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -15,6 +15,7 @@
 #include <linux/ftrace.h>
 #include <linux/uaccess.h>
 #include <linux/module.h>
+#include <linux/stop_machine.h>
 
 #include <asm/cacheflush.h>
 #include <asm/opcodes.h>
@@ -35,6 +36,22 @@
 
 #define	OLD_NOP		0xe1a00000	/* mov r0, r0 */
 
+static int __ftrace_modify_code(void *data)
+{
+	int *command = data;
+
+	set_kernel_text_rw();
+	ftrace_modify_all_code(*command);
+	set_kernel_text_ro();
+
+	return 0;
+}
+
+void arch_ftrace_update_code(int command)
+{
+	stop_machine(__ftrace_modify_code, &command, NULL);
+}
+
 static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
 {
 	return rec->arch.old_mcount ? OLD_NOP : NOP;
@@ -73,6 +90,8 @@ int ftrace_arch_code_modify_prepare(void)
 int ftrace_arch_code_modify_post_process(void)
 {
 	set_all_modules_text_ro();
+	/* Make sure any TLB misses during machine stop are cleared. */
+	flush_tlb_all();
 	return 0;
 }
 
diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
index 8f75250cbe30..4423a565ef6f 100644
--- a/arch/arm/kernel/machine_kexec.c
+++ b/arch/arm/kernel/machine_kexec.c
@@ -164,6 +164,7 @@ void machine_kexec(struct kimage *image)
 	reboot_code_buffer = page_address(image->control_code_page);
 
 	/* Prepare parameters for reboot_code_buffer*/
+	set_kernel_text_rw();
 	kexec_start_address = image->start;
 	kexec_indirection_page = page_list;
 	kexec_mach_type = machine_arch_type;
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index a3d07ca2bbb4..542e58919bd9 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -120,6 +120,9 @@ SECTIONS
 			ARM_CPU_KEEP(PROC_INFO)
 	}
 
+#ifdef CONFIG_DEBUG_RODATA
+	. = ALIGN(1<<SECTION_SHIFT);
+#endif
 	RO_DATA(PAGE_SIZE)
 
 	. = ALIGN(4);
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index 7a0756df91a2..c9cd9c5bf1e1 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -1017,3 +1017,15 @@ config ARM_KERNMEM_PERMS
 	  padded to section-size (1MiB) boundaries (because their permissions
 	  are different and splitting the 1M pages into 4K ones causes TLB
 	  performance problems), wasting memory.
+
+config DEBUG_RODATA
+	bool "Make kernel text and rodata read-only"
+	depends on ARM_KERNMEM_PERMS
+	default y
+	help
+	  If this is set, kernel text and rodata will be made read-only. This
+	  is to help catch accidental or malicious attempts to change the
+	  kernel's executable code. Additionally splits rodata from kernel
+	  text so it can be made explicitly non-executable. This creates
+	  another section-size padded region, so it can waste more memory
+	  space while gaining the read-only protections.
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index ccf392ef40d4..1a0248a9cfdb 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -626,6 +626,7 @@ struct section_perm {
 	unsigned long end;
 	pmdval_t mask;
 	pmdval_t prot;
+	pmdval_t clear;
 };
 
 struct section_perm nx_perms[] = {
@@ -643,8 +644,35 @@ struct section_perm nx_perms[] = {
 		.mask	= ~PMD_SECT_XN,
 		.prot	= PMD_SECT_XN,
 	},
+#ifdef CONFIG_DEBUG_RODATA
+	/* Make rodata NX (set RO in ro_perms below). */
+	{
+		.start  = (unsigned long)__start_rodata,
+		.end    = (unsigned long)__init_begin,
+		.mask   = ~PMD_SECT_XN,
+		.prot   = PMD_SECT_XN,
+	},
+#endif
 };
 
+#ifdef CONFIG_DEBUG_RODATA
+struct section_perm ro_perms[] = {
+	/* Make kernel code and rodata RX (set RO). */
+	{
+		.start  = (unsigned long)_stext,
+		.end    = (unsigned long)__init_begin,
+#ifdef CONFIG_ARM_LPAE
+		.mask   = ~PMD_SECT_RDONLY,
+		.prot   = PMD_SECT_RDONLY,
+#else
+		.mask   = ~(PMD_SECT_APX | PMD_SECT_AP_WRITE),
+		.prot   = PMD_SECT_APX | PMD_SECT_AP_WRITE,
+		.clear  = PMD_SECT_AP_WRITE,
+#endif
+	},
+};
+#endif
+
 /*
  * Updates section permissions only for the current mm (sections are
  * copied into each mm). During startup, this is the init_mm.
@@ -713,6 +741,24 @@ static inline void fix_kernmem_perms(void)
 {
 	set_section_perms(nx_perms, prot);
 }
+
+#ifdef CONFIG_DEBUG_RODATA
+void mark_rodata_ro(void)
+{
+	set_section_perms(ro_perms, prot);
+}
+
+void set_kernel_text_rw(void)
+{
+	set_section_perms(ro_perms, clear);
+}
+
+void set_kernel_text_ro(void)
+{
+	set_section_perms(ro_perms, prot);
+}
+#endif /* CONFIG_DEBUG_RODATA */
+
 #else
 static inline void fix_kernmem_perms(void) { }
 #endif /* CONFIG_ARM_KERNMEM_PERMS */
-- 
1.9.1

^ permalink raw reply related	[flat|nested] 30+ messages in thread
* Re: [PATCH v3 5/7] arm: kgdb: Handle read-only text / modules
  2014-08-12 18:24   ` Kees Cook
@ 2014-08-12 19:38     ` Stephen Boyd
  -1 siblings, 0 replies; 30+ messages in thread
From: Stephen Boyd @ 2014-08-12 19:38 UTC (permalink / raw)
  To: Kees Cook
  Cc: linux-kernel, Nicolas Pitre, Rob Herring, Laura Abbott, Liu hua,
	Catalin Marinas, Tomasz Figa, Jason Wessel, Will Deacon,
	Doug Anderson, Leif Lindholm, Doug Anderson, Rabin Vincent,
	Nikolay Borisov, Mark Salter, Russell King - ARM Linux,
	linux-arm-kernel

On 08/12/14 11:24, Kees Cook wrote:
> @@ -244,6 +248,32 @@ void kgdb_arch_exit(void)
>  	unregister_die_notifier(&kgdb_notifier);
>  }
>  
> +int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
> +{
> +	int err;
> +
> +	/* patch_text() only supports int-sized breakpoints */
> +	if (sizeof(int) != BREAK_INSTR_SIZE)
> +		return -EINVAL;

Could this be a BUILD_BUG_ON too?

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation


^ permalink raw reply	[flat|nested] 30+ messages in thread
* [PATCH v3 5/7] arm: kgdb: Handle read-only text / modules
@ 2014-08-12 19:38     ` Stephen Boyd
  0 siblings, 0 replies; 30+ messages in thread
From: Stephen Boyd @ 2014-08-12 19:38 UTC (permalink / raw)
  To: linux-arm-kernel

On 08/12/14 11:24, Kees Cook wrote:
> @@ -244,6 +248,32 @@ void kgdb_arch_exit(void)
>  	unregister_die_notifier(&kgdb_notifier);
>  }
>  
> +int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
> +{
> +	int err;
> +
> +	/* patch_text() only supports int-sized breakpoints */
> +	if (sizeof(int) != BREAK_INSTR_SIZE)
> +		return -EINVAL;

Could this be a BUILD_BUG_ON too?

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

^ permalink raw reply	[flat|nested] 30+ messages in thread
* Re: [PATCH v3 1/7] arm: use generic fixmap.h
  2014-08-12 18:24   ` Kees Cook
@ 2014-08-12 19:38     ` Kees Cook
  -1 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 19:38 UTC (permalink / raw)
  To: LKML
  Cc: Kees Cook, Mark Salter, Laura Abbott, Rob Herring, Leif Lindholm,
	Rabin Vincent, Liu hua, Nikolay Borisov, Nicolas Pitre,
	Tomasz Figa, Doug Anderson, Jason Wessel, Will Deacon,
	Catalin Marinas, Russell King - ARM Linux, linux-arm-kernel

On Tue, Aug 12, 2014 at 11:24 AM, Kees Cook <keescook@chromium.org> wrote:
> From: Mark Salter <msalter@redhat.com>
>
> ARM is different from other architectures in that fixmap pages are indexed
> with a positive offset from FIXADDR_START.  Other architectures index with
> a negative offset from FIXADDR_TOP.  In order to use the generic fixmap.h
> definitions, this patch redefines FIXADDR_TOP to be inclusive of the
> useable range.  That is, FIXADDR_TOP is the virtual address of the topmost
> fixed page.  The newly defined FIXADDR_END is the first virtual address
> past the fixed mappings.
>
> Signed-off-by: Mark Salter <msalter@redhat.com>
> Reviewed-by: Doug Anderson <dianders@chromium.org>
> [kees: update for a05e54c103b0b8 "ARM: 8031/2: change fixmap ..."]
> [kees: fixed highmem usage, thanks to Laura Abbott and Rob Herring]
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Cc: Laura Abbott <lauraa@codeaurora.org>
> Cc: Rob Herring <robh@kernel.org>
> ---
>  arch/arm/include/asm/fixmap.h  | 27 +++++++++------------------
>  arch/arm/include/asm/highmem.h |  1 -
>  arch/arm/mm/highmem.c          | 15 ++++++++-------
>  arch/arm/mm/init.c             |  2 +-
>  arch/arm/mm/mmu.c              |  6 +++---
>  5 files changed, 21 insertions(+), 30 deletions(-)
>
> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
> index 74124b0d0d79..a7add6f9315d 100644
> --- a/arch/arm/include/asm/fixmap.h
> +++ b/arch/arm/include/asm/fixmap.h
> @@ -2,27 +2,18 @@
>  #define _ASM_FIXMAP_H
>
>  #define FIXADDR_START          0xffc00000UL
> -#define FIXADDR_TOP            0xffe00000UL
> -#define FIXADDR_SIZE           (FIXADDR_TOP - FIXADDR_START)
> +#define FIXADDR_END            0xffe00000UL
> +#define FIXADDR_TOP            (FIXADDR_END - PAGE_SIZE)
>
> -#define FIX_KMAP_NR_PTES       (FIXADDR_SIZE >> PAGE_SHIFT)
> +#include <asm/kmap_types.h>
>
> -#define __fix_to_virt(x)       (FIXADDR_START + ((x) << PAGE_SHIFT))
> -#define __virt_to_fix(x)       (((x) - FIXADDR_START) >> PAGE_SHIFT)
> +enum fixed_addresses {
> +       FIX_KMAP_BEGIN,
> +       FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * NR_CPUS) - 1,
>
> -extern void __this_fixmap_does_not_exist(void);
> +       __end_of_fixed_addresses
> +};
>
> -static inline unsigned long fix_to_virt(const unsigned int idx)
> -{
> -       if (idx >= FIX_KMAP_NR_PTES)
> -               __this_fixmap_does_not_exist();
> -       return __fix_to_virt(idx);
> -}
> -
> -static inline unsigned int virt_to_fix(const unsigned long vaddr)
> -{
> -       BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
> -       return __virt_to_fix(vaddr);
> -}
> +#include <asm-generic/fixmap.h>
>
>  #endif
> diff --git a/arch/arm/include/asm/highmem.h b/arch/arm/include/asm/highmem.h
> index 535579511ed0..91b99abe7a95 100644
> --- a/arch/arm/include/asm/highmem.h
> +++ b/arch/arm/include/asm/highmem.h
> @@ -18,7 +18,6 @@
>         } while (0)
>
>  extern pte_t *pkmap_page_table;
> -extern pte_t *fixmap_page_table;
>
>  extern void *kmap_high(struct page *page);
>  extern void kunmap_high(struct page *page);
> diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
> index 45aeaaca9052..f87e0b89b738 100644
> --- a/arch/arm/mm/highmem.c
> +++ b/arch/arm/mm/highmem.c
> @@ -18,19 +18,20 @@
>  #include <asm/tlbflush.h>
>  #include "mm.h"
>
> -pte_t *fixmap_page_table;
> -
>  static inline void set_fixmap_pte(int idx, pte_t pte)
>  {
>         unsigned long vaddr = __fix_to_virt(idx);
> -       set_pte_ext(fixmap_page_table + idx, pte, 0);
> +       pte_t *ppte = pte_offset_kernel(pmd_off_k(FIXADDR_START), vaddr);
> +
> +       set_pte_ext(ppte, pte, 0);
>         local_flush_tlb_kernel_page(vaddr);
>  }
>
>  static inline pte_t get_fixmap_pte(unsigned long vaddr)
>  {
> -       unsigned long idx = __virt_to_fix(vaddr);
> -       return *(fixmap_page_table + idx);
> +       pte_t *ppte = pte_offset_kernel(pmd_off_k(FIXADDR_START), vaddr);
> +
> +       return *ppte;
>  }
>
>  void *kmap(struct page *page)
> @@ -84,7 +85,7 @@ void *kmap_atomic(struct page *page)
>          * With debugging enabled, kunmap_atomic forces that entry to 0.
>          * Make sure it was indeed properly unmapped.
>          */
> -       BUG_ON(!pte_none(*(fixmap_page_table + idx)));
> +       BUG_ON(!pte_none(*get_fixmap_pte(vaddr)));
>  #endif

Buildbot noticed that with CONFIG_DEBUG_HIGHMEM, this and the next
instance shouldn't have the leading "*" in front of the get_fixmap_pte
call. I've fixed that in my tree.

>         /*
>          * When debugging is off, kunmap_atomic leaves the previous mapping
> @@ -134,7 +135,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
>         idx = type + KM_TYPE_NR * smp_processor_id();
>         vaddr = __fix_to_virt(idx);
>  #ifdef CONFIG_DEBUG_HIGHMEM
> -       BUG_ON(!pte_none(*(fixmap_page_table + idx)));
> +       BUG_ON(!pte_none(*get_fixmap_pte(vaddr)));
>  #endif

Here too, as above.

-Kees

>         set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
>
> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index 659c75d808dc..ad82c05bfc3a 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -570,7 +570,7 @@ void __init mem_init(void)
>                         MLK(DTCM_OFFSET, (unsigned long) dtcm_end),
>                         MLK(ITCM_OFFSET, (unsigned long) itcm_end),
>  #endif
> -                       MLK(FIXADDR_START, FIXADDR_TOP),
> +                       MLK(FIXADDR_START, FIXADDR_END),
>                         MLM(VMALLOC_START, VMALLOC_END),
>                         MLM(PAGE_OFFSET, (unsigned long)high_memory),
>  #ifdef CONFIG_HIGHMEM
> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> index 8348ed6b2efe..7fa0966cd15f 100644
> --- a/arch/arm/mm/mmu.c
> +++ b/arch/arm/mm/mmu.c
> @@ -1326,10 +1326,10 @@ static void __init kmap_init(void)
>  #ifdef CONFIG_HIGHMEM
>         pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE),
>                 PKMAP_BASE, _PAGE_KERNEL_TABLE);
> -
> -       fixmap_page_table = early_pte_alloc(pmd_off_k(FIXADDR_START),
> -               FIXADDR_START, _PAGE_KERNEL_TABLE);
>  #endif
> +
> +       early_pte_alloc(pmd_off_k(FIXADDR_START), FIXADDR_START,
> +                       _PAGE_KERNEL_TABLE);
>  }
>
>  static void __init map_lowmem(void)
> --
> 1.9.1
>



-- 
Kees Cook
Chrome OS Security

^ permalink raw reply	[flat|nested] 30+ messages in thread
* [PATCH v3 1/7] arm: use generic fixmap.h
@ 2014-08-12 19:38     ` Kees Cook
  0 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 19:38 UTC (permalink / raw)
  To: linux-arm-kernel

On Tue, Aug 12, 2014 at 11:24 AM, Kees Cook <keescook@chromium.org> wrote:
> From: Mark Salter <msalter@redhat.com>
>
> ARM is different from other architectures in that fixmap pages are indexed
> with a positive offset from FIXADDR_START.  Other architectures index with
> a negative offset from FIXADDR_TOP.  In order to use the generic fixmap.h
> definitions, this patch redefines FIXADDR_TOP to be inclusive of the
> useable range.  That is, FIXADDR_TOP is the virtual address of the topmost
> fixed page.  The newly defined FIXADDR_END is the first virtual address
> past the fixed mappings.
>
> Signed-off-by: Mark Salter <msalter@redhat.com>
> Reviewed-by: Doug Anderson <dianders@chromium.org>
> [kees: update for a05e54c103b0b8 "ARM: 8031/2: change fixmap ..."]
> [kees: fixed highmem usage, thanks to Laura Abbott and Rob Herring]
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Cc: Laura Abbott <lauraa@codeaurora.org>
> Cc: Rob Herring <robh@kernel.org>
> ---
>  arch/arm/include/asm/fixmap.h  | 27 +++++++++------------------
>  arch/arm/include/asm/highmem.h |  1 -
>  arch/arm/mm/highmem.c          | 15 ++++++++-------
>  arch/arm/mm/init.c             |  2 +-
>  arch/arm/mm/mmu.c              |  6 +++---
>  5 files changed, 21 insertions(+), 30 deletions(-)
>
> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
> index 74124b0d0d79..a7add6f9315d 100644
> --- a/arch/arm/include/asm/fixmap.h
> +++ b/arch/arm/include/asm/fixmap.h
> @@ -2,27 +2,18 @@
>  #define _ASM_FIXMAP_H
>
>  #define FIXADDR_START          0xffc00000UL
> -#define FIXADDR_TOP            0xffe00000UL
> -#define FIXADDR_SIZE           (FIXADDR_TOP - FIXADDR_START)
> +#define FIXADDR_END            0xffe00000UL
> +#define FIXADDR_TOP            (FIXADDR_END - PAGE_SIZE)
>
> -#define FIX_KMAP_NR_PTES       (FIXADDR_SIZE >> PAGE_SHIFT)
> +#include <asm/kmap_types.h>
>
> -#define __fix_to_virt(x)       (FIXADDR_START + ((x) << PAGE_SHIFT))
> -#define __virt_to_fix(x)       (((x) - FIXADDR_START) >> PAGE_SHIFT)
> +enum fixed_addresses {
> +       FIX_KMAP_BEGIN,
> +       FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * NR_CPUS) - 1,
>
> -extern void __this_fixmap_does_not_exist(void);
> +       __end_of_fixed_addresses
> +};
>
> -static inline unsigned long fix_to_virt(const unsigned int idx)
> -{
> -       if (idx >= FIX_KMAP_NR_PTES)
> -               __this_fixmap_does_not_exist();
> -       return __fix_to_virt(idx);
> -}
> -
> -static inline unsigned int virt_to_fix(const unsigned long vaddr)
> -{
> -       BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
> -       return __virt_to_fix(vaddr);
> -}
> +#include <asm-generic/fixmap.h>
>
>  #endif
> diff --git a/arch/arm/include/asm/highmem.h b/arch/arm/include/asm/highmem.h
> index 535579511ed0..91b99abe7a95 100644
> --- a/arch/arm/include/asm/highmem.h
> +++ b/arch/arm/include/asm/highmem.h
> @@ -18,7 +18,6 @@
>         } while (0)
>
>  extern pte_t *pkmap_page_table;
> -extern pte_t *fixmap_page_table;
>
>  extern void *kmap_high(struct page *page);
>  extern void kunmap_high(struct page *page);
> diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
> index 45aeaaca9052..f87e0b89b738 100644
> --- a/arch/arm/mm/highmem.c
> +++ b/arch/arm/mm/highmem.c
> @@ -18,19 +18,20 @@
>  #include <asm/tlbflush.h>
>  #include "mm.h"
>
> -pte_t *fixmap_page_table;
> -
>  static inline void set_fixmap_pte(int idx, pte_t pte)
>  {
>         unsigned long vaddr = __fix_to_virt(idx);
> -       set_pte_ext(fixmap_page_table + idx, pte, 0);
> +       pte_t *ppte = pte_offset_kernel(pmd_off_k(FIXADDR_START), vaddr);
> +
> +       set_pte_ext(ppte, pte, 0);
>         local_flush_tlb_kernel_page(vaddr);
>  }
>
>  static inline pte_t get_fixmap_pte(unsigned long vaddr)
>  {
> -       unsigned long idx = __virt_to_fix(vaddr);
> -       return *(fixmap_page_table + idx);
> +       pte_t *ppte = pte_offset_kernel(pmd_off_k(FIXADDR_START), vaddr);
> +
> +       return *ppte;
>  }
>
>  void *kmap(struct page *page)
> @@ -84,7 +85,7 @@ void *kmap_atomic(struct page *page)
>          * With debugging enabled, kunmap_atomic forces that entry to 0.
>          * Make sure it was indeed properly unmapped.
>          */
> -       BUG_ON(!pte_none(*(fixmap_page_table + idx)));
> +       BUG_ON(!pte_none(*get_fixmap_pte(vaddr)));
>  #endif

Buildbot noticed that with CONFIG_DEBUG_HIGHMEM, this and the next
instance shouldn't have the leading "*" in front of the get_fixmap_pte
call. I've fixed that in my tree.

>         /*
>          * When debugging is off, kunmap_atomic leaves the previous mapping
> @@ -134,7 +135,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
>         idx = type + KM_TYPE_NR * smp_processor_id();
>         vaddr = __fix_to_virt(idx);
>  #ifdef CONFIG_DEBUG_HIGHMEM
> -       BUG_ON(!pte_none(*(fixmap_page_table + idx)));
> +       BUG_ON(!pte_none(*get_fixmap_pte(vaddr)));
>  #endif

Here too, as above.

-Kees

>         set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
>
> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index 659c75d808dc..ad82c05bfc3a 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -570,7 +570,7 @@ void __init mem_init(void)
>                         MLK(DTCM_OFFSET, (unsigned long) dtcm_end),
>                         MLK(ITCM_OFFSET, (unsigned long) itcm_end),
>  #endif
> -                       MLK(FIXADDR_START, FIXADDR_TOP),
> +                       MLK(FIXADDR_START, FIXADDR_END),
>                         MLM(VMALLOC_START, VMALLOC_END),
>                         MLM(PAGE_OFFSET, (unsigned long)high_memory),
>  #ifdef CONFIG_HIGHMEM
> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> index 8348ed6b2efe..7fa0966cd15f 100644
> --- a/arch/arm/mm/mmu.c
> +++ b/arch/arm/mm/mmu.c
> @@ -1326,10 +1326,10 @@ static void __init kmap_init(void)
>  #ifdef CONFIG_HIGHMEM
>         pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE),
>                 PKMAP_BASE, _PAGE_KERNEL_TABLE);
> -
> -       fixmap_page_table = early_pte_alloc(pmd_off_k(FIXADDR_START),
> -               FIXADDR_START, _PAGE_KERNEL_TABLE);
>  #endif
> +
> +       early_pte_alloc(pmd_off_k(FIXADDR_START), FIXADDR_START,
> +                       _PAGE_KERNEL_TABLE);
>  }
>
>  static void __init map_lowmem(void)
> --
> 1.9.1
>



-- 
Kees Cook
Chrome OS Security

^ permalink raw reply	[flat|nested] 30+ messages in thread
* Re: [PATCH v3 5/7] arm: kgdb: Handle read-only text / modules
  2014-08-12 19:38     ` Stephen Boyd
@ 2014-08-12 19:40       ` Kees Cook
  -1 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 19:40 UTC (permalink / raw)
  To: Stephen Boyd
  Cc: LKML, Nicolas Pitre, Rob Herring, Laura Abbott, Liu hua,
	Catalin Marinas, Tomasz Figa, Jason Wessel, Will Deacon,
	Doug Anderson, Leif Lindholm, Doug Anderson, Rabin Vincent,
	Nikolay Borisov, Mark Salter, Russell King - ARM Linux,
	linux-arm-kernel

On Tue, Aug 12, 2014 at 12:38 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
> On 08/12/14 11:24, Kees Cook wrote:
>> @@ -244,6 +248,32 @@ void kgdb_arch_exit(void)
>>       unregister_die_notifier(&kgdb_notifier);
>>  }
>>
>> +int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
>> +{
>> +     int err;
>> +
>> +     /* patch_text() only supports int-sized breakpoints */
>> +     if (sizeof(int) != BREAK_INSTR_SIZE)
>> +             return -EINVAL;
>
> Could this be a BUILD_BUG_ON too?

Ah yes, good call. I'll adjust that.

Thanks!

-Kees

-- 
Kees Cook
Chrome OS Security

^ permalink raw reply	[flat|nested] 30+ messages in thread
* [PATCH v3 5/7] arm: kgdb: Handle read-only text / modules
@ 2014-08-12 19:40       ` Kees Cook
  0 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 19:40 UTC (permalink / raw)
  To: linux-arm-kernel

On Tue, Aug 12, 2014 at 12:38 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
> On 08/12/14 11:24, Kees Cook wrote:
>> @@ -244,6 +248,32 @@ void kgdb_arch_exit(void)
>>       unregister_die_notifier(&kgdb_notifier);
>>  }
>>
>> +int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
>> +{
>> +     int err;
>> +
>> +     /* patch_text() only supports int-sized breakpoints */
>> +     if (sizeof(int) != BREAK_INSTR_SIZE)
>> +             return -EINVAL;
>
> Could this be a BUILD_BUG_ON too?

Ah yes, good call. I'll adjust that.

Thanks!

-Kees

-- 
Kees Cook
Chrome OS Security

^ permalink raw reply	[flat|nested] 30+ messages in thread
* Re: [PATCH v3 3/7] arm: use fixmap for text patching when text is RO
  2014-08-12 18:24   ` Kees Cook
@ 2014-08-12 21:39     ` Stephen Boyd
  -1 siblings, 0 replies; 30+ messages in thread
From: Stephen Boyd @ 2014-08-12 21:39 UTC (permalink / raw)
  To: Kees Cook
  Cc: linux-kernel, Nicolas Pitre, Rob Herring, Laura Abbott, Liu hua,
	Catalin Marinas, Tomasz Figa, Jason Wessel, Will Deacon,
	Leif Lindholm, Doug Anderson, Rabin Vincent, Nikolay Borisov,
	Mark Salter, Russell King - ARM Linux, linux-arm-kernel

On 08/12/14 11:24, Kees Cook wrote:
> diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
> index 07314af47733..03dd4e39c833 100644
> --- a/arch/arm/kernel/patch.c
> +++ b/arch/arm/kernel/patch.c
> @@ -13,21 +16,69 @@ struct patch {
>  	unsigned int insn;
>  };
>  
> -void __kprobes __patch_text(void *addr, unsigned int insn)
> +static DEFINE_SPINLOCK(patch_lock);
> +
> +static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
> +{
> +	unsigned int uintaddr = (uintptr_t) addr;
> +	bool module = !core_kernel_text(uintaddr);
> +	struct page *page;
> +
> +	if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
> +		page = vmalloc_to_page(addr);
> +	else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
> +		page = virt_to_page(addr);
> +	else
> +		return addr;
> +
> +	if (flags)
> +		spin_lock_irqsave(&patch_lock, *flags);
> +
> +	set_fixmap(fixmap, page_to_phys(page));
> +
> +	return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
> +}
> +
> +static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
> +{
> +	clear_fixmap(fixmap);
> +
> +	if (flags)
> +		spin_unlock_irqrestore(&patch_lock, *flags);
> +}

Has the kbuildbot complained about this one yet?

  CHECK  arch/arm/kernel/patch.c
  arch/arm/kernel/patch.c:47:39: warning: context imbalance in
'patch_unmap' - unexpected unlock

I guess we're going to ignore it.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation


^ permalink raw reply	[flat|nested] 30+ messages in thread
* [PATCH v3 3/7] arm: use fixmap for text patching when text is RO
@ 2014-08-12 21:39     ` Stephen Boyd
  0 siblings, 0 replies; 30+ messages in thread
From: Stephen Boyd @ 2014-08-12 21:39 UTC (permalink / raw)
  To: linux-arm-kernel

On 08/12/14 11:24, Kees Cook wrote:
> diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
> index 07314af47733..03dd4e39c833 100644
> --- a/arch/arm/kernel/patch.c
> +++ b/arch/arm/kernel/patch.c
> @@ -13,21 +16,69 @@ struct patch {
>  	unsigned int insn;
>  };
>  
> -void __kprobes __patch_text(void *addr, unsigned int insn)
> +static DEFINE_SPINLOCK(patch_lock);
> +
> +static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
> +{
> +	unsigned int uintaddr = (uintptr_t) addr;
> +	bool module = !core_kernel_text(uintaddr);
> +	struct page *page;
> +
> +	if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
> +		page = vmalloc_to_page(addr);
> +	else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
> +		page = virt_to_page(addr);
> +	else
> +		return addr;
> +
> +	if (flags)
> +		spin_lock_irqsave(&patch_lock, *flags);
> +
> +	set_fixmap(fixmap, page_to_phys(page));
> +
> +	return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
> +}
> +
> +static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
> +{
> +	clear_fixmap(fixmap);
> +
> +	if (flags)
> +		spin_unlock_irqrestore(&patch_lock, *flags);
> +}

Has the kbuildbot complained about this one yet?

  CHECK  arch/arm/kernel/patch.c
  arch/arm/kernel/patch.c:47:39: warning: context imbalance in
'patch_unmap' - unexpected unlock

I guess we're going to ignore it.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

^ permalink raw reply	[flat|nested] 30+ messages in thread
* Re: [PATCH v3 3/7] arm: use fixmap for text patching when text is RO
  2014-08-12 21:39     ` Stephen Boyd
@ 2014-08-12 21:47       ` Kees Cook
  -1 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 21:47 UTC (permalink / raw)
  To: Stephen Boyd
  Cc: LKML, Nicolas Pitre, Rob Herring, Laura Abbott, Liu hua,
	Catalin Marinas, Tomasz Figa, Jason Wessel, Will Deacon,
	Leif Lindholm, Doug Anderson, Rabin Vincent, Nikolay Borisov,
	Mark Salter, Russell King - ARM Linux, linux-arm-kernel

On Tue, Aug 12, 2014 at 2:39 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
> On 08/12/14 11:24, Kees Cook wrote:
>> diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
>> index 07314af47733..03dd4e39c833 100644
>> --- a/arch/arm/kernel/patch.c
>> +++ b/arch/arm/kernel/patch.c
>> @@ -13,21 +16,69 @@ struct patch {
>>       unsigned int insn;
>>  };
>>
>> -void __kprobes __patch_text(void *addr, unsigned int insn)
>> +static DEFINE_SPINLOCK(patch_lock);
>> +
>> +static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
>> +{
>> +     unsigned int uintaddr = (uintptr_t) addr;
>> +     bool module = !core_kernel_text(uintaddr);
>> +     struct page *page;
>> +
>> +     if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
>> +             page = vmalloc_to_page(addr);
>> +     else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
>> +             page = virt_to_page(addr);
>> +     else
>> +             return addr;
>> +
>> +     if (flags)
>> +             spin_lock_irqsave(&patch_lock, *flags);
>> +
>> +     set_fixmap(fixmap, page_to_phys(page));
>> +
>> +     return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
>> +}
>> +
>> +static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
>> +{
>> +     clear_fixmap(fixmap);
>> +
>> +     if (flags)
>> +             spin_unlock_irqrestore(&patch_lock, *flags);
>> +}
>
> Has the kbuildbot complained about this one yet?
>
>   CHECK  arch/arm/kernel/patch.c
>   arch/arm/kernel/patch.c:47:39: warning: context imbalance in
> 'patch_unmap' - unexpected unlock
>
> I guess we're going to ignore it.

No, nothing yet from buildbot, let me do a sparse run -- I think we
can just add annotation and we'll be okay.

-Kees

-- 
Kees Cook
Chrome OS Security

^ permalink raw reply	[flat|nested] 30+ messages in thread
* [PATCH v3 3/7] arm: use fixmap for text patching when text is RO
@ 2014-08-12 21:47       ` Kees Cook
  0 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-12 21:47 UTC (permalink / raw)
  To: linux-arm-kernel

On Tue, Aug 12, 2014 at 2:39 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
> On 08/12/14 11:24, Kees Cook wrote:
>> diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
>> index 07314af47733..03dd4e39c833 100644
>> --- a/arch/arm/kernel/patch.c
>> +++ b/arch/arm/kernel/patch.c
>> @@ -13,21 +16,69 @@ struct patch {
>>       unsigned int insn;
>>  };
>>
>> -void __kprobes __patch_text(void *addr, unsigned int insn)
>> +static DEFINE_SPINLOCK(patch_lock);
>> +
>> +static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
>> +{
>> +     unsigned int uintaddr = (uintptr_t) addr;
>> +     bool module = !core_kernel_text(uintaddr);
>> +     struct page *page;
>> +
>> +     if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
>> +             page = vmalloc_to_page(addr);
>> +     else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
>> +             page = virt_to_page(addr);
>> +     else
>> +             return addr;
>> +
>> +     if (flags)
>> +             spin_lock_irqsave(&patch_lock, *flags);
>> +
>> +     set_fixmap(fixmap, page_to_phys(page));
>> +
>> +     return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
>> +}
>> +
>> +static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
>> +{
>> +     clear_fixmap(fixmap);
>> +
>> +     if (flags)
>> +             spin_unlock_irqrestore(&patch_lock, *flags);
>> +}
>
> Has the kbuildbot complained about this one yet?
>
>   CHECK  arch/arm/kernel/patch.c
>   arch/arm/kernel/patch.c:47:39: warning: context imbalance in
> 'patch_unmap' - unexpected unlock
>
> I guess we're going to ignore it.

No, nothing yet from buildbot, let me do a sparse run -- I think we
can just add annotation and we'll be okay.

-Kees

-- 
Kees Cook
Chrome OS Security

^ permalink raw reply	[flat|nested] 30+ messages in thread
* Re: [PATCH v3 3/7] arm: use fixmap for text patching when text is RO
  2014-08-12 21:47       ` Kees Cook
@ 2014-08-13  0:27         ` Stephen Boyd
  -1 siblings, 0 replies; 30+ messages in thread
From: Stephen Boyd @ 2014-08-13  0:27 UTC (permalink / raw)
  To: Kees Cook
  Cc: LKML, Nicolas Pitre, Rob Herring, Laura Abbott, Liu hua,
	Catalin Marinas, Tomasz Figa, Jason Wessel, Will Deacon,
	Leif Lindholm, Doug Anderson, Rabin Vincent, Nikolay Borisov,
	Mark Salter, Russell King - ARM Linux, linux-arm-kernel

On 08/12/14 14:47, Kees Cook wrote:
> On Tue, Aug 12, 2014 at 2:39 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
>> On 08/12/14 11:24, Kees Cook wrote:
>>> diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
>>> index 07314af47733..03dd4e39c833 100644
>>> --- a/arch/arm/kernel/patch.c
>>> +++ b/arch/arm/kernel/patch.c
>>> @@ -13,21 +16,69 @@ struct patch {
>>>       unsigned int insn;
>>>  };
>>>
>>> -void __kprobes __patch_text(void *addr, unsigned int insn)
>>> +static DEFINE_SPINLOCK(patch_lock);
>>> +
>>> +static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
>>> +{
>>> +     unsigned int uintaddr = (uintptr_t) addr;
>>> +     bool module = !core_kernel_text(uintaddr);
>>> +     struct page *page;
>>> +
>>> +     if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
>>> +             page = vmalloc_to_page(addr);
>>> +     else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
>>> +             page = virt_to_page(addr);
>>> +     else
>>> +             return addr;
>>> +
>>> +     if (flags)
>>> +             spin_lock_irqsave(&patch_lock, *flags);
>>> +
>>> +     set_fixmap(fixmap, page_to_phys(page));
>>> +
>>> +     return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
>>> +}
>>> +
>>> +static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
>>> +{
>>> +     clear_fixmap(fixmap);
>>> +
>>> +     if (flags)
>>> +             spin_unlock_irqrestore(&patch_lock, *flags);
>>> +}
>> Has the kbuildbot complained about this one yet?
>>
>>   CHECK  arch/arm/kernel/patch.c
>>   arch/arm/kernel/patch.c:47:39: warning: context imbalance in
>> 'patch_unmap' - unexpected unlock
>>
>> I guess we're going to ignore it.
> No, nothing yet from buildbot, let me do a sparse run -- I think we
> can just add annotation and we'll be okay.
>
>

Ok. I tried to move code around but sparse still complains because of
conditional locking.

---8<---

diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
index 03dd4e39c833..f6d4de3826a0 100644
--- a/arch/arm/kernel/patch.c
+++ b/arch/arm/kernel/patch.c
@@ -18,33 +18,17 @@ struct patch {
 
 static DEFINE_SPINLOCK(patch_lock);
 
-static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
+static struct page __kprobes *patch_page(void *addr)
 {
 	unsigned int uintaddr = (uintptr_t) addr;
 	bool module = !core_kernel_text(uintaddr);
-	struct page *page;
 
 	if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
-		page = vmalloc_to_page(addr);
+		return vmalloc_to_page(addr);
 	else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
-		page = virt_to_page(addr);
-	else
-		return addr;
+		return virt_to_page(addr);
 
-	if (flags)
-		spin_lock_irqsave(&patch_lock, *flags);
-
-	set_fixmap(fixmap, page_to_phys(page));
-
-	return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
-}
-
-static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
-{
-	clear_fixmap(fixmap);
-
-	if (flags)
-		spin_unlock_irqrestore(&patch_lock, *flags);
+	return NULL;
 }
 
 void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
@@ -54,10 +38,18 @@ void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
 	bool twopage = false;
 	unsigned long flags;
 	void *waddr = addr;
+	struct page *page = NULL;
 	int size;
 
-	if (remap)
-		waddr = patch_map(addr, FIX_TEXT_POKE0, &flags);
+	if (remap) {
+		page = patch_page(addr);
+		if (page) {
+			spin_lock_irqsave(&patch_lock, flags);
+			set_fixmap(FIX_TEXT_POKE0, page_to_phys(page));
+			waddr = (void *)(__fix_to_virt(FIX_TEXT_POKE0) +
+				(uintaddr & ~PAGE_MASK));
+		}
+	}
 
 	if (thumb2 && __opcode_is_thumb16(insn)) {
 		*(u16 *)waddr = __opcode_to_mem_thumb16(insn);
@@ -69,15 +61,25 @@ void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
 		u16 *addrh1 = waddr + 2;
 
 		twopage = (uintaddr & ~PAGE_MASK) == PAGE_SIZE - 2;
-		if (twopage && remap)
-			addrh1 = patch_map(addr + 2, FIX_TEXT_POKE1, NULL);
+		if (twopage && remap) {
+			struct page *page2;
+
+			page2 = patch_page(addr + 2);
+			if (page2) {
+				set_fixmap(FIX_TEXT_POKE1, page_to_phys(page));
+				addrh1 = (u16 *)(__fix_to_virt(FIX_TEXT_POKE1) +
+						(uintaddr & ~PAGE_MASK));
+			} else {
+				addrh1 = addr + 2;
+			}
+		}
 
 		*addrh0 = __opcode_to_mem_thumb16(first);
 		*addrh1 = __opcode_to_mem_thumb16(second);
 
 		if (twopage && addrh1 != addr + 2) {
 			flush_kernel_vmap_range(addrh1, 2);
-			patch_unmap(FIX_TEXT_POKE1, NULL);
+			clear_fixmap(FIX_TEXT_POKE1);
 		}
 
 		size = sizeof(u32);
@@ -91,9 +93,10 @@ void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
 		size = sizeof(u32);
 	}
 
-	if (waddr != addr) {
+	if (page) {
 		flush_kernel_vmap_range(waddr, twopage ? size / 2 : size);
-		patch_unmap(FIX_TEXT_POKE0, &flags);
+		clear_fixmap(FIX_TEXT_POKE0);
+		spin_unlock_irqrestore(&patch_lock, flags);
 	}
 
 	flush_icache_range((uintptr_t)(addr),

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation


^ permalink raw reply related	[flat|nested] 30+ messages in thread
* [PATCH v3 3/7] arm: use fixmap for text patching when text is RO
@ 2014-08-13  0:27         ` Stephen Boyd
  0 siblings, 0 replies; 30+ messages in thread
From: Stephen Boyd @ 2014-08-13  0:27 UTC (permalink / raw)
  To: linux-arm-kernel

On 08/12/14 14:47, Kees Cook wrote:
> On Tue, Aug 12, 2014 at 2:39 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
>> On 08/12/14 11:24, Kees Cook wrote:
>>> diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
>>> index 07314af47733..03dd4e39c833 100644
>>> --- a/arch/arm/kernel/patch.c
>>> +++ b/arch/arm/kernel/patch.c
>>> @@ -13,21 +16,69 @@ struct patch {
>>>       unsigned int insn;
>>>  };
>>>
>>> -void __kprobes __patch_text(void *addr, unsigned int insn)
>>> +static DEFINE_SPINLOCK(patch_lock);
>>> +
>>> +static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
>>> +{
>>> +     unsigned int uintaddr = (uintptr_t) addr;
>>> +     bool module = !core_kernel_text(uintaddr);
>>> +     struct page *page;
>>> +
>>> +     if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
>>> +             page = vmalloc_to_page(addr);
>>> +     else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
>>> +             page = virt_to_page(addr);
>>> +     else
>>> +             return addr;
>>> +
>>> +     if (flags)
>>> +             spin_lock_irqsave(&patch_lock, *flags);
>>> +
>>> +     set_fixmap(fixmap, page_to_phys(page));
>>> +
>>> +     return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
>>> +}
>>> +
>>> +static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
>>> +{
>>> +     clear_fixmap(fixmap);
>>> +
>>> +     if (flags)
>>> +             spin_unlock_irqrestore(&patch_lock, *flags);
>>> +}
>> Has the kbuildbot complained about this one yet?
>>
>>   CHECK  arch/arm/kernel/patch.c
>>   arch/arm/kernel/patch.c:47:39: warning: context imbalance in
>> 'patch_unmap' - unexpected unlock
>>
>> I guess we're going to ignore it.
> No, nothing yet from buildbot, let me do a sparse run -- I think we
> can just add annotation and we'll be okay.
>
>

Ok. I tried to move code around but sparse still complains because of
conditional locking.

---8<---

diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
index 03dd4e39c833..f6d4de3826a0 100644
--- a/arch/arm/kernel/patch.c
+++ b/arch/arm/kernel/patch.c
@@ -18,33 +18,17 @@ struct patch {
 
 static DEFINE_SPINLOCK(patch_lock);
 
-static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
+static struct page __kprobes *patch_page(void *addr)
 {
 	unsigned int uintaddr = (uintptr_t) addr;
 	bool module = !core_kernel_text(uintaddr);
-	struct page *page;
 
 	if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
-		page = vmalloc_to_page(addr);
+		return vmalloc_to_page(addr);
 	else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
-		page = virt_to_page(addr);
-	else
-		return addr;
+		return virt_to_page(addr);
 
-	if (flags)
-		spin_lock_irqsave(&patch_lock, *flags);
-
-	set_fixmap(fixmap, page_to_phys(page));
-
-	return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
-}
-
-static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
-{
-	clear_fixmap(fixmap);
-
-	if (flags)
-		spin_unlock_irqrestore(&patch_lock, *flags);
+	return NULL;
 }
 
 void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
@@ -54,10 +38,18 @@ void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
 	bool twopage = false;
 	unsigned long flags;
 	void *waddr = addr;
+	struct page *page = NULL;
 	int size;
 
-	if (remap)
-		waddr = patch_map(addr, FIX_TEXT_POKE0, &flags);
+	if (remap) {
+		page = patch_page(addr);
+		if (page) {
+			spin_lock_irqsave(&patch_lock, flags);
+			set_fixmap(FIX_TEXT_POKE0, page_to_phys(page));
+			waddr = (void *)(__fix_to_virt(FIX_TEXT_POKE0) +
+				(uintaddr & ~PAGE_MASK));
+		}
+	}
 
 	if (thumb2 && __opcode_is_thumb16(insn)) {
 		*(u16 *)waddr = __opcode_to_mem_thumb16(insn);
@@ -69,15 +61,25 @@ void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
 		u16 *addrh1 = waddr + 2;
 
 		twopage = (uintaddr & ~PAGE_MASK) == PAGE_SIZE - 2;
-		if (twopage && remap)
-			addrh1 = patch_map(addr + 2, FIX_TEXT_POKE1, NULL);
+		if (twopage && remap) {
+			struct page *page2;
+
+			page2 = patch_page(addr + 2);
+			if (page2) {
+				set_fixmap(FIX_TEXT_POKE1, page_to_phys(page));
+				addrh1 = (u16 *)(__fix_to_virt(FIX_TEXT_POKE1) +
+						(uintaddr & ~PAGE_MASK));
+			} else {
+				addrh1 = addr + 2;
+			}
+		}
 
 		*addrh0 = __opcode_to_mem_thumb16(first);
 		*addrh1 = __opcode_to_mem_thumb16(second);
 
 		if (twopage && addrh1 != addr + 2) {
 			flush_kernel_vmap_range(addrh1, 2);
-			patch_unmap(FIX_TEXT_POKE1, NULL);
+			clear_fixmap(FIX_TEXT_POKE1);
 		}
 
 		size = sizeof(u32);
@@ -91,9 +93,10 @@ void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
 		size = sizeof(u32);
 	}
 
-	if (waddr != addr) {
+	if (page) {
 		flush_kernel_vmap_range(waddr, twopage ? size / 2 : size);
-		patch_unmap(FIX_TEXT_POKE0, &flags);
+		clear_fixmap(FIX_TEXT_POKE0);
+		spin_unlock_irqrestore(&patch_lock, flags);
 	}
 
 	flush_icache_range((uintptr_t)(addr),

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

^ permalink raw reply related	[flat|nested] 30+ messages in thread
* Re: [PATCH v3 3/7] arm: use fixmap for text patching when text is RO
  2014-08-13  0:27         ` Stephen Boyd
@ 2014-08-13  2:39           ` Kees Cook
  -1 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-13  2:39 UTC (permalink / raw)
  To: Stephen Boyd
  Cc: LKML, Nicolas Pitre, Rob Herring, Laura Abbott, Liu hua,
	Catalin Marinas, Tomasz Figa, Jason Wessel, Will Deacon,
	Leif Lindholm, Doug Anderson, Rabin Vincent, Nikolay Borisov,
	Mark Salter, Russell King - ARM Linux, linux-arm-kernel

On Tue, Aug 12, 2014 at 5:27 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
> On 08/12/14 14:47, Kees Cook wrote:
>> On Tue, Aug 12, 2014 at 2:39 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
>>> On 08/12/14 11:24, Kees Cook wrote:
>>>> diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
>>>> index 07314af47733..03dd4e39c833 100644
>>>> --- a/arch/arm/kernel/patch.c
>>>> +++ b/arch/arm/kernel/patch.c
>>>> @@ -13,21 +16,69 @@ struct patch {
>>>>       unsigned int insn;
>>>>  };
>>>>
>>>> -void __kprobes __patch_text(void *addr, unsigned int insn)
>>>> +static DEFINE_SPINLOCK(patch_lock);
>>>> +
>>>> +static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
>>>> +{
>>>> +     unsigned int uintaddr = (uintptr_t) addr;
>>>> +     bool module = !core_kernel_text(uintaddr);
>>>> +     struct page *page;
>>>> +
>>>> +     if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
>>>> +             page = vmalloc_to_page(addr);
>>>> +     else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
>>>> +             page = virt_to_page(addr);
>>>> +     else
>>>> +             return addr;
>>>> +
>>>> +     if (flags)
>>>> +             spin_lock_irqsave(&patch_lock, *flags);
>>>> +
>>>> +     set_fixmap(fixmap, page_to_phys(page));
>>>> +
>>>> +     return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
>>>> +}
>>>> +
>>>> +static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
>>>> +{
>>>> +     clear_fixmap(fixmap);
>>>> +
>>>> +     if (flags)
>>>> +             spin_unlock_irqrestore(&patch_lock, *flags);
>>>> +}
>>> Has the kbuildbot complained about this one yet?
>>>
>>>   CHECK  arch/arm/kernel/patch.c
>>>   arch/arm/kernel/patch.c:47:39: warning: context imbalance in
>>> 'patch_unmap' - unexpected unlock
>>>
>>> I guess we're going to ignore it.
>> No, nothing yet from buildbot, let me do a sparse run -- I think we
>> can just add annotation and we'll be okay.
>>
>>
>
> Ok. I tried to move code around but sparse still complains because of
> conditional locking.

Oh, sorry! I should have mentioned I fixed this already. It just
requires some declarations. Here's how it looks now:

https://git.kernel.org/cgit/linux/kernel/git/kees/linux.git/commit/?h=arm/ro-nx&id=847a4a489d31b76797e7c7a78cd3e98c7948df4b

+static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
+ __acquires(&patch_lock)
+{
...
+ if (flags)
+ spin_lock_irqsave(&patch_lock, *flags);
+ else
+ __acquire(&patch_lock);

etc.

Thanks for poking at this!

-Kees

>
> ---8<---
>
> diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
> index 03dd4e39c833..f6d4de3826a0 100644
> --- a/arch/arm/kernel/patch.c
> +++ b/arch/arm/kernel/patch.c
> @@ -18,33 +18,17 @@ struct patch {
>
>  static DEFINE_SPINLOCK(patch_lock);
>
> -static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
> +static struct page __kprobes *patch_page(void *addr)
>  {
>         unsigned int uintaddr = (uintptr_t) addr;
>         bool module = !core_kernel_text(uintaddr);
> -       struct page *page;
>
>         if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
> -               page = vmalloc_to_page(addr);
> +               return vmalloc_to_page(addr);
>         else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
> -               page = virt_to_page(addr);
> -       else
> -               return addr;
> +               return virt_to_page(addr);
>
> -       if (flags)
> -               spin_lock_irqsave(&patch_lock, *flags);
> -
> -       set_fixmap(fixmap, page_to_phys(page));
> -
> -       return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
> -}
> -
> -static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
> -{
> -       clear_fixmap(fixmap);
> -
> -       if (flags)
> -               spin_unlock_irqrestore(&patch_lock, *flags);
> +       return NULL;
>  }
>
>  void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
> @@ -54,10 +38,18 @@ void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
>         bool twopage = false;
>         unsigned long flags;
>         void *waddr = addr;
> +       struct page *page = NULL;
>         int size;
>
> -       if (remap)
> -               waddr = patch_map(addr, FIX_TEXT_POKE0, &flags);
> +       if (remap) {
> +               page = patch_page(addr);
> +               if (page) {
> +                       spin_lock_irqsave(&patch_lock, flags);
> +                       set_fixmap(FIX_TEXT_POKE0, page_to_phys(page));
> +                       waddr = (void *)(__fix_to_virt(FIX_TEXT_POKE0) +
> +                               (uintaddr & ~PAGE_MASK));
> +               }
> +       }
>
>         if (thumb2 && __opcode_is_thumb16(insn)) {
>                 *(u16 *)waddr = __opcode_to_mem_thumb16(insn);
> @@ -69,15 +61,25 @@ void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
>                 u16 *addrh1 = waddr + 2;
>
>                 twopage = (uintaddr & ~PAGE_MASK) == PAGE_SIZE - 2;
> -               if (twopage && remap)
> -                       addrh1 = patch_map(addr + 2, FIX_TEXT_POKE1, NULL);
> +               if (twopage && remap) {
> +                       struct page *page2;
> +
> +                       page2 = patch_page(addr + 2);
> +                       if (page2) {
> +                               set_fixmap(FIX_TEXT_POKE1, page_to_phys(page));
> +                               addrh1 = (u16 *)(__fix_to_virt(FIX_TEXT_POKE1) +
> +                                               (uintaddr & ~PAGE_MASK));
> +                       } else {
> +                               addrh1 = addr + 2;
> +                       }
> +               }
>
>                 *addrh0 = __opcode_to_mem_thumb16(first);
>                 *addrh1 = __opcode_to_mem_thumb16(second);
>
>                 if (twopage && addrh1 != addr + 2) {
>                         flush_kernel_vmap_range(addrh1, 2);
> -                       patch_unmap(FIX_TEXT_POKE1, NULL);
> +                       clear_fixmap(FIX_TEXT_POKE1);
>                 }
>
>                 size = sizeof(u32);
> @@ -91,9 +93,10 @@ void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
>                 size = sizeof(u32);
>         }
>
> -       if (waddr != addr) {
> +       if (page) {
>                 flush_kernel_vmap_range(waddr, twopage ? size / 2 : size);
> -               patch_unmap(FIX_TEXT_POKE0, &flags);
> +               clear_fixmap(FIX_TEXT_POKE0);
> +               spin_unlock_irqrestore(&patch_lock, flags);
>         }
>
>         flush_icache_range((uintptr_t)(addr),
>
> --
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> hosted by The Linux Foundation
>



-- 
Kees Cook
Chrome OS Security

^ permalink raw reply	[flat|nested] 30+ messages in thread
* [PATCH v3 3/7] arm: use fixmap for text patching when text is RO
@ 2014-08-13  2:39           ` Kees Cook
  0 siblings, 0 replies; 30+ messages in thread
From: Kees Cook @ 2014-08-13  2:39 UTC (permalink / raw)
  To: linux-arm-kernel

On Tue, Aug 12, 2014 at 5:27 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
> On 08/12/14 14:47, Kees Cook wrote:
>> On Tue, Aug 12, 2014 at 2:39 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
>>> On 08/12/14 11:24, Kees Cook wrote:
>>>> diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
>>>> index 07314af47733..03dd4e39c833 100644
>>>> --- a/arch/arm/kernel/patch.c
>>>> +++ b/arch/arm/kernel/patch.c
>>>> @@ -13,21 +16,69 @@ struct patch {
>>>>       unsigned int insn;
>>>>  };
>>>>
>>>> -void __kprobes __patch_text(void *addr, unsigned int insn)
>>>> +static DEFINE_SPINLOCK(patch_lock);
>>>> +
>>>> +static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
>>>> +{
>>>> +     unsigned int uintaddr = (uintptr_t) addr;
>>>> +     bool module = !core_kernel_text(uintaddr);
>>>> +     struct page *page;
>>>> +
>>>> +     if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
>>>> +             page = vmalloc_to_page(addr);
>>>> +     else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
>>>> +             page = virt_to_page(addr);
>>>> +     else
>>>> +             return addr;
>>>> +
>>>> +     if (flags)
>>>> +             spin_lock_irqsave(&patch_lock, *flags);
>>>> +
>>>> +     set_fixmap(fixmap, page_to_phys(page));
>>>> +
>>>> +     return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
>>>> +}
>>>> +
>>>> +static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
>>>> +{
>>>> +     clear_fixmap(fixmap);
>>>> +
>>>> +     if (flags)
>>>> +             spin_unlock_irqrestore(&patch_lock, *flags);
>>>> +}
>>> Has the kbuildbot complained about this one yet?
>>>
>>>   CHECK  arch/arm/kernel/patch.c
>>>   arch/arm/kernel/patch.c:47:39: warning: context imbalance in
>>> 'patch_unmap' - unexpected unlock
>>>
>>> I guess we're going to ignore it.
>> No, nothing yet from buildbot, let me do a sparse run -- I think we
>> can just add annotation and we'll be okay.
>>
>>
>
> Ok. I tried to move code around but sparse still complains because of
> conditional locking.

Oh, sorry! I should have mentioned I fixed this already. It just
requires some declarations. Here's how it looks now:

https://git.kernel.org/cgit/linux/kernel/git/kees/linux.git/commit/?h=arm/ro-nx&id=847a4a489d31b76797e7c7a78cd3e98c7948df4b

+static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
+ __acquires(&patch_lock)
+{
...
+ if (flags)
+ spin_lock_irqsave(&patch_lock, *flags);
+ else
+ __acquire(&patch_lock);

etc.

Thanks for poking at this!

-Kees

>
> ---8<---
>
> diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
> index 03dd4e39c833..f6d4de3826a0 100644
> --- a/arch/arm/kernel/patch.c
> +++ b/arch/arm/kernel/patch.c
> @@ -18,33 +18,17 @@ struct patch {
>
>  static DEFINE_SPINLOCK(patch_lock);
>
> -static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
> +static struct page __kprobes *patch_page(void *addr)
>  {
>         unsigned int uintaddr = (uintptr_t) addr;
>         bool module = !core_kernel_text(uintaddr);
> -       struct page *page;
>
>         if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
> -               page = vmalloc_to_page(addr);
> +               return vmalloc_to_page(addr);
>         else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
> -               page = virt_to_page(addr);
> -       else
> -               return addr;
> +               return virt_to_page(addr);
>
> -       if (flags)
> -               spin_lock_irqsave(&patch_lock, *flags);
> -
> -       set_fixmap(fixmap, page_to_phys(page));
> -
> -       return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
> -}
> -
> -static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
> -{
> -       clear_fixmap(fixmap);
> -
> -       if (flags)
> -               spin_unlock_irqrestore(&patch_lock, *flags);
> +       return NULL;
>  }
>
>  void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
> @@ -54,10 +38,18 @@ void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
>         bool twopage = false;
>         unsigned long flags;
>         void *waddr = addr;
> +       struct page *page = NULL;
>         int size;
>
> -       if (remap)
> -               waddr = patch_map(addr, FIX_TEXT_POKE0, &flags);
> +       if (remap) {
> +               page = patch_page(addr);
> +               if (page) {
> +                       spin_lock_irqsave(&patch_lock, flags);
> +                       set_fixmap(FIX_TEXT_POKE0, page_to_phys(page));
> +                       waddr = (void *)(__fix_to_virt(FIX_TEXT_POKE0) +
> +                               (uintaddr & ~PAGE_MASK));
> +               }
> +       }
>
>         if (thumb2 && __opcode_is_thumb16(insn)) {
>                 *(u16 *)waddr = __opcode_to_mem_thumb16(insn);
> @@ -69,15 +61,25 @@ void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
>                 u16 *addrh1 = waddr + 2;
>
>                 twopage = (uintaddr & ~PAGE_MASK) == PAGE_SIZE - 2;
> -               if (twopage && remap)
> -                       addrh1 = patch_map(addr + 2, FIX_TEXT_POKE1, NULL);
> +               if (twopage && remap) {
> +                       struct page *page2;
> +
> +                       page2 = patch_page(addr + 2);
> +                       if (page2) {
> +                               set_fixmap(FIX_TEXT_POKE1, page_to_phys(page));
> +                               addrh1 = (u16 *)(__fix_to_virt(FIX_TEXT_POKE1) +
> +                                               (uintaddr & ~PAGE_MASK));
> +                       } else {
> +                               addrh1 = addr + 2;
> +                       }
> +               }
>
>                 *addrh0 = __opcode_to_mem_thumb16(first);
>                 *addrh1 = __opcode_to_mem_thumb16(second);
>
>                 if (twopage && addrh1 != addr + 2) {
>                         flush_kernel_vmap_range(addrh1, 2);
> -                       patch_unmap(FIX_TEXT_POKE1, NULL);
> +                       clear_fixmap(FIX_TEXT_POKE1);
>                 }
>
>                 size = sizeof(u32);
> @@ -91,9 +93,10 @@ void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
>                 size = sizeof(u32);
>         }
>
> -       if (waddr != addr) {
> +       if (page) {
>                 flush_kernel_vmap_range(waddr, twopage ? size / 2 : size);
> -               patch_unmap(FIX_TEXT_POKE0, &flags);
> +               clear_fixmap(FIX_TEXT_POKE0);
> +               spin_unlock_irqrestore(&patch_lock, flags);
>         }
>
>         flush_icache_range((uintptr_t)(addr),
>
> --
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> hosted by The Linux Foundation
>



-- 
Kees Cook
Chrome OS Security

^ permalink raw reply	[flat|nested] 30+ messages in thread
end of thread, other threads:[~2014-08-13  2:39 UTC | newest]

Thread overview: 30+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-08-12 18:24 [PATCH v3 0/7] arm: support CONFIG_RODATA Kees Cook
2014-08-12 18:24 ` Kees Cook
2014-08-12 18:24 ` [PATCH v3 1/7] arm: use generic fixmap.h Kees Cook
2014-08-12 18:24   ` Kees Cook
2014-08-12 19:38   ` Kees Cook
2014-08-12 19:38     ` Kees Cook
2014-08-12 18:24 ` [PATCH v3 2/7] arm: fixmap: implement __set_fixmap() Kees Cook
2014-08-12 18:24   ` Kees Cook
2014-08-12 18:24 ` [PATCH v3 3/7] arm: use fixmap for text patching when text is RO Kees Cook
2014-08-12 18:24   ` Kees Cook
2014-08-12 21:39   ` Stephen Boyd
2014-08-12 21:39     ` Stephen Boyd
2014-08-12 21:47     ` Kees Cook
2014-08-12 21:47       ` Kees Cook
2014-08-13  0:27       ` Stephen Boyd
2014-08-13  0:27         ` Stephen Boyd
2014-08-13  2:39         ` Kees Cook
2014-08-13  2:39           ` Kees Cook
2014-08-12 18:24 ` [PATCH v3 4/7] ARM: kexec: Make .text R/W in machine_kexec Kees Cook
2014-08-12 18:24   ` Kees Cook
2014-08-12 18:24 ` [PATCH v3 5/7] arm: kgdb: Handle read-only text / modules Kees Cook
2014-08-12 18:24   ` Kees Cook
2014-08-12 19:38   ` Stephen Boyd
2014-08-12 19:38     ` Stephen Boyd
2014-08-12 19:40     ` Kees Cook
2014-08-12 19:40       ` Kees Cook
2014-08-12 18:24 ` [PATCH v3 6/7] ARM: mm: allow non-text sections to be non-executable Kees Cook
2014-08-12 18:24   ` Kees Cook
2014-08-12 18:24 ` [PATCH v3 7/7] ARM: mm: allow text and rodata sections to be read-only Kees Cook
2014-08-12 18:24   ` Kees Cook

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