* [PATCH v13 1/8] powerpc/mm: Implement set_memory() routines
2021-05-10 1:18 [PATCH v13 0/8] powerpc: Further Strict RWX support Jordan Niethe
@ 2021-05-10 1:18 ` Jordan Niethe
2021-05-13 2:08 ` Jordan Niethe
2021-05-10 1:18 ` [PATCH v13 2/8] powerpc/lib/code-patching: Set up Strict RWX patching earlier Jordan Niethe
` (6 subsequent siblings)
7 siblings, 1 reply; 13+ messages in thread
From: Jordan Niethe @ 2021-05-10 1:18 UTC (permalink / raw)
To: linuxppc-dev
Cc: ajd, cmr, npiggin, aneesh.kumar, naveen.n.rao, Jordan Niethe, dja
From: Russell Currey <ruscur@russell.cc>
The set_memory_{ro/rw/nx/x}() functions are required for
STRICT_MODULE_RWX, and are generally useful primitives to have. This
implementation is designed to be generic across powerpc's many MMUs.
It's possible that this could be optimised to be faster for specific
MMUs.
This implementation does not handle cases where the caller is attempting
to change the mapping of the page it is executing from, or if another
CPU is concurrently using the page being altered. These cases likely
shouldn't happen, but a more complex implementation with MMU-specific code
could safely handle them.
On hash, the linear mapping is not kept in the linux pagetable, so this
will not change the protection if used on that range. Currently these
functions are not used on the linear map so just WARN for now.
apply_to_existing_page_range() does not work on huge pages so for now
disallow changing the protection of huge pages.
Reviewed-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[jpn: - Allow set memory functions to be used without Strict RWX
- Hash: Disallow certain regions
- Have change_page_attr() take function pointers to manipulate ptes
- Radix: Add ptesync after set_pte_at()]
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
---
v10: WARN if trying to change the hash linear map
v11: - Update copywrite dates
- Allow set memory functions to be used without Strict RWX
- Hash: Disallow certain regions and add comment explaining why
- Have change_page_attr() take function pointers to manipulate ptes
- Clarify change_page_attr()'s comment
- Radix: Add ptesync after set_pte_at()
v12: - change_page_attr() back to taking an action value
- disallow operating on huge pages
---
arch/powerpc/Kconfig | 1 +
arch/powerpc/include/asm/set_memory.h | 32 +++++++++
arch/powerpc/mm/Makefile | 2 +-
arch/powerpc/mm/pageattr.c | 100 ++++++++++++++++++++++++++
4 files changed, 134 insertions(+), 1 deletion(-)
create mode 100644 arch/powerpc/include/asm/set_memory.h
create mode 100644 arch/powerpc/mm/pageattr.c
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 3f863dd21374..cce0a137b046 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -138,6 +138,7 @@ config PPC
select ARCH_HAS_MEMBARRIER_CALLBACKS
select ARCH_HAS_MEMBARRIER_SYNC_CORE
select ARCH_HAS_SCALED_CPUTIME if VIRT_CPU_ACCOUNTING_NATIVE && PPC_BOOK3S_64
+ select ARCH_HAS_SET_MEMORY
select ARCH_HAS_STRICT_KERNEL_RWX if ((PPC_BOOK3S_64 || PPC32) && !HIBERNATION)
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_HAS_UACCESS_FLUSHCACHE
diff --git a/arch/powerpc/include/asm/set_memory.h b/arch/powerpc/include/asm/set_memory.h
new file mode 100644
index 000000000000..64011ea444b4
--- /dev/null
+++ b/arch/powerpc/include/asm/set_memory.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_POWERPC_SET_MEMORY_H
+#define _ASM_POWERPC_SET_MEMORY_H
+
+#define SET_MEMORY_RO 0
+#define SET_MEMORY_RW 1
+#define SET_MEMORY_NX 2
+#define SET_MEMORY_X 3
+
+int change_memory_attr(unsigned long addr, int numpages, long action);
+
+static inline int set_memory_ro(unsigned long addr, int numpages)
+{
+ return change_memory_attr(addr, numpages, SET_MEMORY_RO);
+}
+
+static inline int set_memory_rw(unsigned long addr, int numpages)
+{
+ return change_memory_attr(addr, numpages, SET_MEMORY_RW);
+}
+
+static inline int set_memory_nx(unsigned long addr, int numpages)
+{
+ return change_memory_attr(addr, numpages, SET_MEMORY_NX);
+}
+
+static inline int set_memory_x(unsigned long addr, int numpages)
+{
+ return change_memory_attr(addr, numpages, SET_MEMORY_X);
+}
+
+#endif
diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile
index c3df3a8501d4..9142cf1fb0d5 100644
--- a/arch/powerpc/mm/Makefile
+++ b/arch/powerpc/mm/Makefile
@@ -5,7 +5,7 @@
ccflags-$(CONFIG_PPC64) := $(NO_MINIMAL_TOC)
-obj-y := fault.o mem.o pgtable.o mmap.o maccess.o \
+obj-y := fault.o mem.o pgtable.o mmap.o maccess.o pageattr.o \
init_$(BITS).o pgtable_$(BITS).o \
pgtable-frag.o ioremap.o ioremap_$(BITS).o \
init-common.o mmu_context.o drmem.o \
diff --git a/arch/powerpc/mm/pageattr.c b/arch/powerpc/mm/pageattr.c
new file mode 100644
index 000000000000..acfdde78e0fb
--- /dev/null
+++ b/arch/powerpc/mm/pageattr.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * MMU-generic set_memory implementation for powerpc
+ *
+ * Copyright 2019-2021, IBM Corporation.
+ */
+
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <linux/set_memory.h>
+
+#include <asm/mmu.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+
+
+/*
+ * Updates the attributes of a page in three steps:
+ *
+ * 1. invalidate the page table entry
+ * 2. flush the TLB
+ * 3. install the new entry with the updated attributes
+ *
+ * Invalidating the pte means there are situations where this will not work
+ * when in theory it should.
+ * For example:
+ * - removing write from page whilst it is being executed
+ * - setting a page read-only whilst it is being read by another CPU
+ *
+ */
+static int change_page_attr(pte_t *ptep, unsigned long addr, void *data)
+{
+ long action = (long)data;
+ pte_t pte;
+
+ spin_lock(&init_mm.page_table_lock);
+
+ /* invalidate the PTE so it's safe to modify */
+ pte = ptep_get_and_clear(&init_mm, addr, ptep);
+ flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
+
+ /* modify the PTE bits as desired, then apply */
+ switch (action) {
+ case SET_MEMORY_RO:
+ pte = pte_wrprotect(pte);
+ break;
+ case SET_MEMORY_RW:
+ pte = pte_mkwrite(pte_mkdirty(pte));
+ break;
+ case SET_MEMORY_NX:
+ pte = pte_exprotect(pte);
+ break;
+ case SET_MEMORY_X:
+ pte = pte_mkexec(pte);
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ break;
+ }
+
+ set_pte_at(&init_mm, addr, ptep, pte);
+
+ /* See ptesync comment in radix__set_pte_at() */
+ if (radix_enabled())
+ asm volatile("ptesync": : :"memory");
+ spin_unlock(&init_mm.page_table_lock);
+
+ return 0;
+}
+
+int change_memory_attr(unsigned long addr, int numpages, long action)
+{
+ unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE);
+ unsigned long size = numpages * PAGE_SIZE;
+
+ if (!numpages)
+ return 0;
+
+ if (WARN_ON_ONCE(is_vm_area_hugepages((void *)addr)))
+ return -EINVAL;
+
+#ifdef CONFIG_PPC_BOOK3S_64
+ /*
+ * On hash, the linear mapping is not in the Linux page table so
+ * apply_to_existing_page_range() will have no effect. If in the future
+ * the set_memory_* functions are used on the linear map this will need
+ * to be updated.
+ */
+ if (!radix_enabled()) {
+ int region = get_region_id(addr);
+
+ if (WARN_ON_ONCE(region != VMALLOC_REGION_ID && region != IO_REGION_ID))
+ return -EINVAL;
+ }
+#endif
+
+ return apply_to_existing_page_range(&init_mm, start, size,
+ change_page_attr, (void *)action);
+}
--
2.25.1
^ permalink raw reply related [flat|nested] 13+ messages in thread* Re: [PATCH v13 1/8] powerpc/mm: Implement set_memory() routines
2021-05-10 1:18 ` [PATCH v13 1/8] powerpc/mm: Implement set_memory() routines Jordan Niethe
@ 2021-05-13 2:08 ` Jordan Niethe
0 siblings, 0 replies; 13+ messages in thread
From: Jordan Niethe @ 2021-05-13 2:08 UTC (permalink / raw)
To: linuxppc-dev
Cc: ajd, cmr, Nicholas Piggin, Aneesh Kumar K.V, naveen.n.rao, Daniel Axtens
On Mon, May 10, 2021 at 11:18 AM Jordan Niethe <jniethe5@gmail.com> wrote:
>
> From: Russell Currey <ruscur@russell.cc>
>
> The set_memory_{ro/rw/nx/x}() functions are required for
> STRICT_MODULE_RWX, and are generally useful primitives to have. This
> implementation is designed to be generic across powerpc's many MMUs.
> It's possible that this could be optimised to be faster for specific
> MMUs.
>
> This implementation does not handle cases where the caller is attempting
> to change the mapping of the page it is executing from, or if another
> CPU is concurrently using the page being altered. These cases likely
> shouldn't happen, but a more complex implementation with MMU-specific code
> could safely handle them.
>
> On hash, the linear mapping is not kept in the linux pagetable, so this
> will not change the protection if used on that range. Currently these
> functions are not used on the linear map so just WARN for now.
>
> apply_to_existing_page_range() does not work on huge pages so for now
> disallow changing the protection of huge pages.
>
> Reviewed-by: Daniel Axtens <dja@axtens.net>
> Signed-off-by: Russell Currey <ruscur@russell.cc>
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> [jpn: - Allow set memory functions to be used without Strict RWX
> - Hash: Disallow certain regions
> - Have change_page_attr() take function pointers to manipulate ptes
> - Radix: Add ptesync after set_pte_at()]
> Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
> ---
> v10: WARN if trying to change the hash linear map
> v11: - Update copywrite dates
> - Allow set memory functions to be used without Strict RWX
> - Hash: Disallow certain regions and add comment explaining why
> - Have change_page_attr() take function pointers to manipulate ptes
> - Clarify change_page_attr()'s comment
> - Radix: Add ptesync after set_pte_at()
> v12: - change_page_attr() back to taking an action value
> - disallow operating on huge pages
> ---
> arch/powerpc/Kconfig | 1 +
> arch/powerpc/include/asm/set_memory.h | 32 +++++++++
> arch/powerpc/mm/Makefile | 2 +-
> arch/powerpc/mm/pageattr.c | 100 ++++++++++++++++++++++++++
> 4 files changed, 134 insertions(+), 1 deletion(-)
> create mode 100644 arch/powerpc/include/asm/set_memory.h
> create mode 100644 arch/powerpc/mm/pageattr.c
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 3f863dd21374..cce0a137b046 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -138,6 +138,7 @@ config PPC
> select ARCH_HAS_MEMBARRIER_CALLBACKS
> select ARCH_HAS_MEMBARRIER_SYNC_CORE
> select ARCH_HAS_SCALED_CPUTIME if VIRT_CPU_ACCOUNTING_NATIVE && PPC_BOOK3S_64
> + select ARCH_HAS_SET_MEMORY
> select ARCH_HAS_STRICT_KERNEL_RWX if ((PPC_BOOK3S_64 || PPC32) && !HIBERNATION)
> select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
> select ARCH_HAS_UACCESS_FLUSHCACHE
> diff --git a/arch/powerpc/include/asm/set_memory.h b/arch/powerpc/include/asm/set_memory.h
> new file mode 100644
> index 000000000000..64011ea444b4
> --- /dev/null
> +++ b/arch/powerpc/include/asm/set_memory.h
> @@ -0,0 +1,32 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_POWERPC_SET_MEMORY_H
> +#define _ASM_POWERPC_SET_MEMORY_H
> +
> +#define SET_MEMORY_RO 0
> +#define SET_MEMORY_RW 1
> +#define SET_MEMORY_NX 2
> +#define SET_MEMORY_X 3
> +
> +int change_memory_attr(unsigned long addr, int numpages, long action);
> +
> +static inline int set_memory_ro(unsigned long addr, int numpages)
> +{
> + return change_memory_attr(addr, numpages, SET_MEMORY_RO);
> +}
> +
> +static inline int set_memory_rw(unsigned long addr, int numpages)
> +{
> + return change_memory_attr(addr, numpages, SET_MEMORY_RW);
> +}
> +
> +static inline int set_memory_nx(unsigned long addr, int numpages)
> +{
> + return change_memory_attr(addr, numpages, SET_MEMORY_NX);
> +}
> +
> +static inline int set_memory_x(unsigned long addr, int numpages)
> +{
> + return change_memory_attr(addr, numpages, SET_MEMORY_X);
> +}
> +
> +#endif
> diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile
> index c3df3a8501d4..9142cf1fb0d5 100644
> --- a/arch/powerpc/mm/Makefile
> +++ b/arch/powerpc/mm/Makefile
> @@ -5,7 +5,7 @@
>
> ccflags-$(CONFIG_PPC64) := $(NO_MINIMAL_TOC)
>
> -obj-y := fault.o mem.o pgtable.o mmap.o maccess.o \
> +obj-y := fault.o mem.o pgtable.o mmap.o maccess.o pageattr.o \
> init_$(BITS).o pgtable_$(BITS).o \
> pgtable-frag.o ioremap.o ioremap_$(BITS).o \
> init-common.o mmu_context.o drmem.o \
> diff --git a/arch/powerpc/mm/pageattr.c b/arch/powerpc/mm/pageattr.c
> new file mode 100644
> index 000000000000..acfdde78e0fb
> --- /dev/null
> +++ b/arch/powerpc/mm/pageattr.c
> @@ -0,0 +1,100 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * MMU-generic set_memory implementation for powerpc
> + *
> + * Copyright 2019-2021, IBM Corporation.
> + */
> +
> +#include <linux/mm.h>
> +#include <linux/vmalloc.h>
> +#include <linux/set_memory.h>
> +
> +#include <asm/mmu.h>
> +#include <asm/page.h>
> +#include <asm/pgtable.h>
> +
> +
> +/*
> + * Updates the attributes of a page in three steps:
> + *
> + * 1. invalidate the page table entry
> + * 2. flush the TLB
> + * 3. install the new entry with the updated attributes
> + *
> + * Invalidating the pte means there are situations where this will not work
> + * when in theory it should.
> + * For example:
> + * - removing write from page whilst it is being executed
> + * - setting a page read-only whilst it is being read by another CPU
> + *
> + */
> +static int change_page_attr(pte_t *ptep, unsigned long addr, void *data)
> +{
> + long action = (long)data;
> + pte_t pte;
> +
> + spin_lock(&init_mm.page_table_lock);
> +
> + /* invalidate the PTE so it's safe to modify */
> + pte = ptep_get_and_clear(&init_mm, addr, ptep);
> + flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
> +
> + /* modify the PTE bits as desired, then apply */
> + switch (action) {
> + case SET_MEMORY_RO:
> + pte = pte_wrprotect(pte);
> + break;
> + case SET_MEMORY_RW:
> + pte = pte_mkwrite(pte_mkdirty(pte));
> + break;
> + case SET_MEMORY_NX:
> + pte = pte_exprotect(pte);
> + break;
> + case SET_MEMORY_X:
> + pte = pte_mkexec(pte);
> + break;
> + default:
> + WARN_ON_ONCE(1);
> + break;
> + }
> +
> + set_pte_at(&init_mm, addr, ptep, pte);
> +
> + /* See ptesync comment in radix__set_pte_at() */
> + if (radix_enabled())
> + asm volatile("ptesync": : :"memory");
> + spin_unlock(&init_mm.page_table_lock);
> +
> + return 0;
> +}
> +
> +int change_memory_attr(unsigned long addr, int numpages, long action)
> +{
> + unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE);
> + unsigned long size = numpages * PAGE_SIZE;
> +
> + if (!numpages)
> + return 0;
> +
> + if (WARN_ON_ONCE(is_vm_area_hugepages((void *)addr)))
> + return -EINVAL;
I think this test actually needs to be something like
if (WARN_ON_ONCE(is_vmalloc_or_module_addr((void *)addr) &&
is_vm_area_hugepages((void *)addr)))
> +
> +#ifdef CONFIG_PPC_BOOK3S_64
> + /*
> + * On hash, the linear mapping is not in the Linux page table so
> + * apply_to_existing_page_range() will have no effect. If in the future
> + * the set_memory_* functions are used on the linear map this will need
> + * to be updated.
> + */
> + if (!radix_enabled()) {
> + int region = get_region_id(addr);
> +
> + if (WARN_ON_ONCE(region != VMALLOC_REGION_ID && region != IO_REGION_ID))
> + return -EINVAL;
> + }
> +#endif
> +
> + return apply_to_existing_page_range(&init_mm, start, size,
> + change_page_attr, (void *)action);
> +}
> --
> 2.25.1
>
^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH v13 2/8] powerpc/lib/code-patching: Set up Strict RWX patching earlier
2021-05-10 1:18 [PATCH v13 0/8] powerpc: Further Strict RWX support Jordan Niethe
2021-05-10 1:18 ` [PATCH v13 1/8] powerpc/mm: Implement set_memory() routines Jordan Niethe
@ 2021-05-10 1:18 ` Jordan Niethe
2021-05-10 1:18 ` [PATCH v13 3/8] powerpc/kprobes: Mark newly allocated probes as ROX Jordan Niethe
` (5 subsequent siblings)
7 siblings, 0 replies; 13+ messages in thread
From: Jordan Niethe @ 2021-05-10 1:18 UTC (permalink / raw)
To: linuxppc-dev
Cc: ajd, cmr, npiggin, aneesh.kumar, naveen.n.rao, Jordan Niethe, dja
setup_text_poke_area() is a late init call so it runs before
mark_rodata_ro() and after the init calls. This lets all the init code
patching simply write to their locations. In the future, kprobes is
going to allocate its instruction pages RO which means they will need
setup_text__poke_area() to have been already called for their code
patching. However, init_kprobes() (which allocates and patches some
instruction pages) is an early init call so it happens before
setup_text__poke_area().
start_kernel() calls poking_init() before any of the init calls. On
powerpc, poking_init() is currently a nop. setup_text_poke_area() relies
on kernel virtual memory, cpu hotplug and per_cpu_areas being setup.
setup_per_cpu_areas(), boot_cpu_hotplug_init() and mm_init() are called
before poking_init().
Turn setup_text_poke_area() into poking_init().
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
---
v9: New to series
---
arch/powerpc/lib/code-patching.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index 870b30d9be2f..15296207e1ba 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -70,14 +70,11 @@ static int text_area_cpu_down(unsigned int cpu)
}
/*
- * Run as a late init call. This allows all the boot time patching to be done
- * simply by patching the code, and then we're called here prior to
- * mark_rodata_ro(), which happens after all init calls are run. Although
- * BUG_ON() is rude, in this case it should only happen if ENOMEM, and we judge
- * it as being preferable to a kernel that will crash later when someone tries
- * to use patch_instruction().
+ * Although BUG_ON() is rude, in this case it should only happen if ENOMEM, and
+ * we judge it as being preferable to a kernel that will crash later when
+ * someone tries to use patch_instruction().
*/
-static int __init setup_text_poke_area(void)
+int __init poking_init(void)
{
BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
"powerpc/text_poke:online", text_area_cpu_up,
@@ -85,7 +82,6 @@ static int __init setup_text_poke_area(void)
return 0;
}
-late_initcall(setup_text_poke_area);
/*
* This can be called for kernel text or a module.
--
2.25.1
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCH v13 3/8] powerpc/kprobes: Mark newly allocated probes as ROX
2021-05-10 1:18 [PATCH v13 0/8] powerpc: Further Strict RWX support Jordan Niethe
2021-05-10 1:18 ` [PATCH v13 1/8] powerpc/mm: Implement set_memory() routines Jordan Niethe
2021-05-10 1:18 ` [PATCH v13 2/8] powerpc/lib/code-patching: Set up Strict RWX patching earlier Jordan Niethe
@ 2021-05-10 1:18 ` Jordan Niethe
2021-05-14 5:48 ` Christophe Leroy
2021-05-10 1:18 ` [PATCH v13 4/8] powerpc/bpf: Remove bpf_jit_free() Jordan Niethe
` (4 subsequent siblings)
7 siblings, 1 reply; 13+ messages in thread
From: Jordan Niethe @ 2021-05-10 1:18 UTC (permalink / raw)
To: linuxppc-dev
Cc: ajd, cmr, npiggin, aneesh.kumar, naveen.n.rao, Jordan Niethe, dja
From: Russell Currey <ruscur@russell.cc>
Add the arch specific insn page allocator for powerpc. This allocates
ROX pages if STRICT_KERNEL_RWX is enabled. These pages are only written
to with patch_instruction() which is able to write RO pages.
Reviewed-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[jpn: Reword commit message, switch to __vmalloc_node_range()]
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
---
v9: - vmalloc_exec() no longer exists
- Set the page to RW before freeing it
v10: - use __vmalloc_node_range()
v11: - Neaten up
v12: - Switch from __vmalloc_node_range() to module_alloc()
v13: Use strict_kernel_rwx_enabled()
---
arch/powerpc/kernel/kprobes.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 01ab2163659e..b517f3e6e7c5 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -19,11 +19,13 @@
#include <linux/extable.h>
#include <linux/kdebug.h>
#include <linux/slab.h>
+#include <linux/moduleloader.h>
#include <asm/code-patching.h>
#include <asm/cacheflush.h>
#include <asm/sstep.h>
#include <asm/sections.h>
#include <asm/inst.h>
+#include <asm/set_memory.h>
#include <linux/uaccess.h>
DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
@@ -103,6 +105,21 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
return addr;
}
+void *alloc_insn_page(void)
+{
+ void *page;
+
+ page = module_alloc(PAGE_SIZE);
+ if (!page)
+ return NULL;
+
+ if (strict_kernel_rwx_enabled()) {
+ set_memory_ro((unsigned long)page, 1);
+ set_memory_x((unsigned long)page, 1);
+ }
+ return page;
+}
+
int arch_prepare_kprobe(struct kprobe *p)
{
int ret = 0;
--
2.25.1
^ permalink raw reply related [flat|nested] 13+ messages in thread* Re: [PATCH v13 3/8] powerpc/kprobes: Mark newly allocated probes as ROX
2021-05-10 1:18 ` [PATCH v13 3/8] powerpc/kprobes: Mark newly allocated probes as ROX Jordan Niethe
@ 2021-05-14 5:48 ` Christophe Leroy
0 siblings, 0 replies; 13+ messages in thread
From: Christophe Leroy @ 2021-05-14 5:48 UTC (permalink / raw)
To: Jordan Niethe, linuxppc-dev
Cc: ajd, npiggin, cmr, aneesh.kumar, naveen.n.rao, dja
Le 10/05/2021 à 03:18, Jordan Niethe a écrit :
> From: Russell Currey <ruscur@russell.cc>
>
> Add the arch specific insn page allocator for powerpc. This allocates
> ROX pages if STRICT_KERNEL_RWX is enabled. These pages are only written
> to with patch_instruction() which is able to write RO pages.
>
> Reviewed-by: Daniel Axtens <dja@axtens.net>
> Signed-off-by: Russell Currey <ruscur@russell.cc>
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> [jpn: Reword commit message, switch to __vmalloc_node_range()]
> Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
> ---
> v9: - vmalloc_exec() no longer exists
> - Set the page to RW before freeing it
> v10: - use __vmalloc_node_range()
> v11: - Neaten up
> v12: - Switch from __vmalloc_node_range() to module_alloc()
> v13: Use strict_kernel_rwx_enabled()
> ---
> arch/powerpc/kernel/kprobes.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
> index 01ab2163659e..b517f3e6e7c5 100644
> --- a/arch/powerpc/kernel/kprobes.c
> +++ b/arch/powerpc/kernel/kprobes.c
> @@ -19,11 +19,13 @@
> #include <linux/extable.h>
> #include <linux/kdebug.h>
> #include <linux/slab.h>
> +#include <linux/moduleloader.h>
> #include <asm/code-patching.h>
> #include <asm/cacheflush.h>
> #include <asm/sstep.h>
> #include <asm/sections.h>
> #include <asm/inst.h>
> +#include <asm/set_memory.h>
> #include <linux/uaccess.h>
>
> DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
> @@ -103,6 +105,21 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
> return addr;
> }
>
> +void *alloc_insn_page(void)
> +{
> + void *page;
> +
> + page = module_alloc(PAGE_SIZE);
> + if (!page)
> + return NULL;
> +
> + if (strict_kernel_rwx_enabled()) {
I'm not sure this is OK.
I think we need to make a new helper strict_module_rwx_enabled() because I don't think we want to
call that when CONFIG_STRICT_MODULE_RWX is not selected.
> + set_memory_ro((unsigned long)page, 1);
> + set_memory_x((unsigned long)page, 1);
> + }
> + return page;
> +}
> +
> int arch_prepare_kprobe(struct kprobe *p)
> {
> int ret = 0;
>
^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH v13 4/8] powerpc/bpf: Remove bpf_jit_free()
2021-05-10 1:18 [PATCH v13 0/8] powerpc: Further Strict RWX support Jordan Niethe
` (2 preceding siblings ...)
2021-05-10 1:18 ` [PATCH v13 3/8] powerpc/kprobes: Mark newly allocated probes as ROX Jordan Niethe
@ 2021-05-10 1:18 ` Jordan Niethe
2021-05-10 1:18 ` [PATCH v13 5/8] powerpc/bpf: Write protect JIT code Jordan Niethe
` (3 subsequent siblings)
7 siblings, 0 replies; 13+ messages in thread
From: Jordan Niethe @ 2021-05-10 1:18 UTC (permalink / raw)
To: linuxppc-dev
Cc: ajd, cmr, npiggin, aneesh.kumar, naveen.n.rao, Jordan Niethe, dja
Commit 74451e66d516 ("bpf: make jited programs visible in traces") added
a default bpf_jit_free() implementation. Powerpc did not use the default
bpf_jit_free() as powerpc did not set the images read-only. The default
bpf_jit_free() called bpf_jit_binary_unlock_ro() is why it could not be
used for powerpc.
Commit d53d2f78cead ("bpf: Use vmalloc special flag") moved keeping
track of read-only memory to vmalloc. This included removing
bpf_jit_binary_unlock_ro(). Therefore there is no reason powerpc needs
its own bpf_jit_free(). Remove it.
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
---
v11: New to series
---
arch/powerpc/net/bpf_jit_comp.c | 12 ------------
1 file changed, 12 deletions(-)
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index 798ac4350a82..6c8c268e4fe8 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -257,15 +257,3 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
return fp;
}
-
-/* Overriding bpf_jit_free() as we don't set images read-only. */
-void bpf_jit_free(struct bpf_prog *fp)
-{
- unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK;
- struct bpf_binary_header *bpf_hdr = (void *)addr;
-
- if (fp->jited)
- bpf_jit_binary_free(bpf_hdr);
-
- bpf_prog_unlock_free(fp);
-}
--
2.25.1
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCH v13 5/8] powerpc/bpf: Write protect JIT code
2021-05-10 1:18 [PATCH v13 0/8] powerpc: Further Strict RWX support Jordan Niethe
` (3 preceding siblings ...)
2021-05-10 1:18 ` [PATCH v13 4/8] powerpc/bpf: Remove bpf_jit_free() Jordan Niethe
@ 2021-05-10 1:18 ` Jordan Niethe
2021-05-10 1:18 ` [PATCH v13 6/8] powerpc: Set ARCH_HAS_STRICT_MODULE_RWX Jordan Niethe
` (2 subsequent siblings)
7 siblings, 0 replies; 13+ messages in thread
From: Jordan Niethe @ 2021-05-10 1:18 UTC (permalink / raw)
To: linuxppc-dev
Cc: ajd, cmr, npiggin, aneesh.kumar, naveen.n.rao, Jordan Niethe, dja
Add the necessary call to bpf_jit_binary_lock_ro() to remove write and
add exec permissions to the JIT image after it has finished being
written.
Without CONFIG_STRICT_MODULE_RWX the image will be writable and
executable until the call to bpf_jit_binary_lock_ro().
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
---
v10: New to series
v11: Remove CONFIG_STRICT_MODULE_RWX conditional
---
arch/powerpc/net/bpf_jit_comp.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index 6c8c268e4fe8..53aefee3fe70 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -237,6 +237,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
fp->jited_len = alloclen;
bpf_flush_icache(bpf_hdr, (u8 *)bpf_hdr + (bpf_hdr->pages * PAGE_SIZE));
+ bpf_jit_binary_lock_ro(bpf_hdr);
if (!fp->is_func || extra_pass) {
bpf_prog_fill_jited_linfo(fp, addrs);
out_addrs:
--
2.25.1
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCH v13 6/8] powerpc: Set ARCH_HAS_STRICT_MODULE_RWX
2021-05-10 1:18 [PATCH v13 0/8] powerpc: Further Strict RWX support Jordan Niethe
` (4 preceding siblings ...)
2021-05-10 1:18 ` [PATCH v13 5/8] powerpc/bpf: Write protect JIT code Jordan Niethe
@ 2021-05-10 1:18 ` Jordan Niethe
2021-05-14 5:50 ` Christophe Leroy
2021-05-10 1:18 ` [PATCH v13 7/8] powerpc/mm: implement set_memory_attr() Jordan Niethe
2021-05-10 1:18 ` [PATCH v13 8/8] powerpc/32: use set_memory_attr() Jordan Niethe
7 siblings, 1 reply; 13+ messages in thread
From: Jordan Niethe @ 2021-05-10 1:18 UTC (permalink / raw)
To: linuxppc-dev
Cc: ajd, cmr, npiggin, aneesh.kumar, naveen.n.rao, Jordan Niethe, dja
From: Russell Currey <ruscur@russell.cc>
To enable strict module RWX on powerpc, set:
CONFIG_STRICT_MODULE_RWX=y
You should also have CONFIG_STRICT_KERNEL_RWX=y set to have any real
security benefit.
ARCH_HAS_STRICT_MODULE_RWX is set to require ARCH_HAS_STRICT_KERNEL_RWX.
This is due to a quirk in arch/Kconfig and arch/powerpc/Kconfig that
makes STRICT_MODULE_RWX *on by default* in configurations where
STRICT_KERNEL_RWX is *unavailable*.
Since this doesn't make much sense, and module RWX without kernel RWX
doesn't make much sense, having the same dependencies as kernel RWX
works around this problem.
With STRICT_MODULE_RWX, now make module_alloc() allocate pages with
KERNEL_PAGE protection rather than KERNEL_PAGE_EXEC.
Book32s/32 processors with a hash mmu (i.e. 604 core) can not set memory
protection on a page by page basis so do not enable.
Signed-off-by: Russell Currey <ruscur@russell.cc>
[jpn: - predicate on !PPC_BOOK3S_604
- make module_alloc() use PAGE_KERNEL protection]
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
---
v10: - Predicate on !PPC_BOOK3S_604
- Make module_alloc() use PAGE_KERNEL protection
v11: - Neaten up
v13: Use strict_kernel_rwx_enabled()
---
arch/powerpc/Kconfig | 1 +
arch/powerpc/kernel/module.c | 4 +++-
2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index cce0a137b046..cb5d9d862c35 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -140,6 +140,7 @@ config PPC
select ARCH_HAS_SCALED_CPUTIME if VIRT_CPU_ACCOUNTING_NATIVE && PPC_BOOK3S_64
select ARCH_HAS_SET_MEMORY
select ARCH_HAS_STRICT_KERNEL_RWX if ((PPC_BOOK3S_64 || PPC32) && !HIBERNATION)
+ select ARCH_HAS_STRICT_MODULE_RWX if ARCH_HAS_STRICT_KERNEL_RWX && !PPC_BOOK3S_604
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_HAS_UACCESS_FLUSHCACHE
select ARCH_HAS_COPY_MC if PPC64
diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c
index 3f35c8d20be7..f24004635ed5 100644
--- a/arch/powerpc/kernel/module.c
+++ b/arch/powerpc/kernel/module.c
@@ -92,12 +92,14 @@ int module_finalize(const Elf_Ehdr *hdr,
static __always_inline void *
__module_alloc(unsigned long size, unsigned long start, unsigned long end)
{
+ pgprot_t prot = strict_kernel_rwx_enabled() ? PAGE_KERNEL : PAGE_KERNEL_EXEC;
+
/*
* Don't do huge page allocations for modules yet until more testing
* is done. STRICT_MODULE_RWX may require extra work to support this
* too.
*/
- return __vmalloc_node_range(size, 1, start, end, GFP_KERNEL, PAGE_KERNEL_EXEC,
+ return __vmalloc_node_range(size, 1, start, end, GFP_KERNEL, prot,
VM_FLUSH_RESET_PERMS | VM_NO_HUGE_VMAP,
NUMA_NO_NODE, __builtin_return_address(0));
}
--
2.25.1
^ permalink raw reply related [flat|nested] 13+ messages in thread* Re: [PATCH v13 6/8] powerpc: Set ARCH_HAS_STRICT_MODULE_RWX
2021-05-10 1:18 ` [PATCH v13 6/8] powerpc: Set ARCH_HAS_STRICT_MODULE_RWX Jordan Niethe
@ 2021-05-14 5:50 ` Christophe Leroy
2021-05-17 1:28 ` Jordan Niethe
0 siblings, 1 reply; 13+ messages in thread
From: Christophe Leroy @ 2021-05-14 5:50 UTC (permalink / raw)
To: Jordan Niethe, linuxppc-dev
Cc: ajd, npiggin, cmr, aneesh.kumar, naveen.n.rao, dja
Le 10/05/2021 à 03:18, Jordan Niethe a écrit :
> From: Russell Currey <ruscur@russell.cc>
>
> To enable strict module RWX on powerpc, set:
>
> CONFIG_STRICT_MODULE_RWX=y
>
> You should also have CONFIG_STRICT_KERNEL_RWX=y set to have any real
> security benefit.
>
> ARCH_HAS_STRICT_MODULE_RWX is set to require ARCH_HAS_STRICT_KERNEL_RWX.
> This is due to a quirk in arch/Kconfig and arch/powerpc/Kconfig that
> makes STRICT_MODULE_RWX *on by default* in configurations where
> STRICT_KERNEL_RWX is *unavailable*.
>
> Since this doesn't make much sense, and module RWX without kernel RWX
> doesn't make much sense, having the same dependencies as kernel RWX
> works around this problem.
>
> With STRICT_MODULE_RWX, now make module_alloc() allocate pages with
> KERNEL_PAGE protection rather than KERNEL_PAGE_EXEC.
>
> Book32s/32 processors with a hash mmu (i.e. 604 core) can not set memory
> protection on a page by page basis so do not enable.
>
> Signed-off-by: Russell Currey <ruscur@russell.cc>
> [jpn: - predicate on !PPC_BOOK3S_604
> - make module_alloc() use PAGE_KERNEL protection]
> Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
> ---
> v10: - Predicate on !PPC_BOOK3S_604
> - Make module_alloc() use PAGE_KERNEL protection
> v11: - Neaten up
> v13: Use strict_kernel_rwx_enabled()
> ---
> arch/powerpc/Kconfig | 1 +
> arch/powerpc/kernel/module.c | 4 +++-
> 2 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index cce0a137b046..cb5d9d862c35 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -140,6 +140,7 @@ config PPC
> select ARCH_HAS_SCALED_CPUTIME if VIRT_CPU_ACCOUNTING_NATIVE && PPC_BOOK3S_64
> select ARCH_HAS_SET_MEMORY
> select ARCH_HAS_STRICT_KERNEL_RWX if ((PPC_BOOK3S_64 || PPC32) && !HIBERNATION)
> + select ARCH_HAS_STRICT_MODULE_RWX if ARCH_HAS_STRICT_KERNEL_RWX && !PPC_BOOK3S_604
> select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
> select ARCH_HAS_UACCESS_FLUSHCACHE
> select ARCH_HAS_COPY_MC if PPC64
> diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c
> index 3f35c8d20be7..f24004635ed5 100644
> --- a/arch/powerpc/kernel/module.c
> +++ b/arch/powerpc/kernel/module.c
> @@ -92,12 +92,14 @@ int module_finalize(const Elf_Ehdr *hdr,
> static __always_inline void *
> __module_alloc(unsigned long size, unsigned long start, unsigned long end)
> {
> + pgprot_t prot = strict_kernel_rwx_enabled() ? PAGE_KERNEL : PAGE_KERNEL_EXEC;
> +
I'm not sure this is OK.
I think we need to make a new helper strict_module_rwx_enabled() because I don't think we want
PAGE_KERNEL here when CONFIG_STRICT_MODULE_RWX is not selected.
> /*
> * Don't do huge page allocations for modules yet until more testing
> * is done. STRICT_MODULE_RWX may require extra work to support this
> * too.
> */
> - return __vmalloc_node_range(size, 1, start, end, GFP_KERNEL, PAGE_KERNEL_EXEC,
> + return __vmalloc_node_range(size, 1, start, end, GFP_KERNEL, prot,
> VM_FLUSH_RESET_PERMS | VM_NO_HUGE_VMAP,
> NUMA_NO_NODE, __builtin_return_address(0));
> }
>
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [PATCH v13 6/8] powerpc: Set ARCH_HAS_STRICT_MODULE_RWX
2021-05-14 5:50 ` Christophe Leroy
@ 2021-05-17 1:28 ` Jordan Niethe
0 siblings, 0 replies; 13+ messages in thread
From: Jordan Niethe @ 2021-05-17 1:28 UTC (permalink / raw)
To: Christophe Leroy
Cc: ajd, Nicholas Piggin, cmr, Aneesh Kumar K.V, naveen.n.rao,
linuxppc-dev, Daniel Axtens
On Fri, May 14, 2021 at 3:50 PM Christophe Leroy
<christophe.leroy@csgroup.eu> wrote:
>
>
>
> Le 10/05/2021 à 03:18, Jordan Niethe a écrit :
> > From: Russell Currey <ruscur@russell.cc>
> >
> > To enable strict module RWX on powerpc, set:
> >
> > CONFIG_STRICT_MODULE_RWX=y
> >
> > You should also have CONFIG_STRICT_KERNEL_RWX=y set to have any real
> > security benefit.
> >
> > ARCH_HAS_STRICT_MODULE_RWX is set to require ARCH_HAS_STRICT_KERNEL_RWX.
> > This is due to a quirk in arch/Kconfig and arch/powerpc/Kconfig that
> > makes STRICT_MODULE_RWX *on by default* in configurations where
> > STRICT_KERNEL_RWX is *unavailable*.
> >
> > Since this doesn't make much sense, and module RWX without kernel RWX
> > doesn't make much sense, having the same dependencies as kernel RWX
> > works around this problem.
> >
> > With STRICT_MODULE_RWX, now make module_alloc() allocate pages with
> > KERNEL_PAGE protection rather than KERNEL_PAGE_EXEC.
> >
> > Book32s/32 processors with a hash mmu (i.e. 604 core) can not set memory
> > protection on a page by page basis so do not enable.
> >
> > Signed-off-by: Russell Currey <ruscur@russell.cc>
> > [jpn: - predicate on !PPC_BOOK3S_604
> > - make module_alloc() use PAGE_KERNEL protection]
> > Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
> > ---
> > v10: - Predicate on !PPC_BOOK3S_604
> > - Make module_alloc() use PAGE_KERNEL protection
> > v11: - Neaten up
> > v13: Use strict_kernel_rwx_enabled()
> > ---
> > arch/powerpc/Kconfig | 1 +
> > arch/powerpc/kernel/module.c | 4 +++-
> > 2 files changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> > index cce0a137b046..cb5d9d862c35 100644
> > --- a/arch/powerpc/Kconfig
> > +++ b/arch/powerpc/Kconfig
> > @@ -140,6 +140,7 @@ config PPC
> > select ARCH_HAS_SCALED_CPUTIME if VIRT_CPU_ACCOUNTING_NATIVE && PPC_BOOK3S_64
> > select ARCH_HAS_SET_MEMORY
> > select ARCH_HAS_STRICT_KERNEL_RWX if ((PPC_BOOK3S_64 || PPC32) && !HIBERNATION)
> > + select ARCH_HAS_STRICT_MODULE_RWX if ARCH_HAS_STRICT_KERNEL_RWX && !PPC_BOOK3S_604
> > select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
> > select ARCH_HAS_UACCESS_FLUSHCACHE
> > select ARCH_HAS_COPY_MC if PPC64
> > diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c
> > index 3f35c8d20be7..f24004635ed5 100644
> > --- a/arch/powerpc/kernel/module.c
> > +++ b/arch/powerpc/kernel/module.c
> > @@ -92,12 +92,14 @@ int module_finalize(const Elf_Ehdr *hdr,
> > static __always_inline void *
> > __module_alloc(unsigned long size, unsigned long start, unsigned long end)
> > {
> > + pgprot_t prot = strict_kernel_rwx_enabled() ? PAGE_KERNEL : PAGE_KERNEL_EXEC;
> > +
>
> I'm not sure this is OK.
>
> I think we need to make a new helper strict_module_rwx_enabled() because I don't think we want
> PAGE_KERNEL here when CONFIG_STRICT_MODULE_RWX is not selected.
Yeah that seems like the right thing to do. I'll send a new version.
>
>
> > /*
> > * Don't do huge page allocations for modules yet until more testing
> > * is done. STRICT_MODULE_RWX may require extra work to support this
> > * too.
> > */
> > - return __vmalloc_node_range(size, 1, start, end, GFP_KERNEL, PAGE_KERNEL_EXEC,
> > + return __vmalloc_node_range(size, 1, start, end, GFP_KERNEL, prot,
> > VM_FLUSH_RESET_PERMS | VM_NO_HUGE_VMAP,
> > NUMA_NO_NODE, __builtin_return_address(0));
> > }
> >
^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH v13 7/8] powerpc/mm: implement set_memory_attr()
2021-05-10 1:18 [PATCH v13 0/8] powerpc: Further Strict RWX support Jordan Niethe
` (5 preceding siblings ...)
2021-05-10 1:18 ` [PATCH v13 6/8] powerpc: Set ARCH_HAS_STRICT_MODULE_RWX Jordan Niethe
@ 2021-05-10 1:18 ` Jordan Niethe
2021-05-10 1:18 ` [PATCH v13 8/8] powerpc/32: use set_memory_attr() Jordan Niethe
7 siblings, 0 replies; 13+ messages in thread
From: Jordan Niethe @ 2021-05-10 1:18 UTC (permalink / raw)
To: linuxppc-dev
Cc: ajd, cmr, kbuild test robot, npiggin, aneesh.kumar, naveen.n.rao,
Jordan Niethe, dja
From: Christophe Leroy <christophe.leroy@csgroup.eu>
In addition to the set_memory_xx() functions which allows to change
the memory attributes of not (yet) used memory regions, implement a
set_memory_attr() function to:
- set the final memory protection after init on currently used
kernel regions.
- enable/disable kernel memory regions in the scope of DEBUG_PAGEALLOC.
Unlike the set_memory_xx() which can act in three step as the regions
are unused, this function must modify 'on the fly' as the kernel is
executing from them. At the moment only PPC32 will use it and changing
page attributes on the fly is not an issue.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reported-by: kbuild test robot <lkp@intel.com>
[ruscur: cast "data" to unsigned long instead of int]
Signed-off-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
---
arch/powerpc/include/asm/set_memory.h | 2 ++
arch/powerpc/mm/pageattr.c | 33 +++++++++++++++++++++++++++
2 files changed, 35 insertions(+)
diff --git a/arch/powerpc/include/asm/set_memory.h b/arch/powerpc/include/asm/set_memory.h
index 64011ea444b4..b040094f7920 100644
--- a/arch/powerpc/include/asm/set_memory.h
+++ b/arch/powerpc/include/asm/set_memory.h
@@ -29,4 +29,6 @@ static inline int set_memory_x(unsigned long addr, int numpages)
return change_memory_attr(addr, numpages, SET_MEMORY_X);
}
+int set_memory_attr(unsigned long addr, int numpages, pgprot_t prot);
+
#endif
diff --git a/arch/powerpc/mm/pageattr.c b/arch/powerpc/mm/pageattr.c
index acfdde78e0fb..7dee30cd6b48 100644
--- a/arch/powerpc/mm/pageattr.c
+++ b/arch/powerpc/mm/pageattr.c
@@ -98,3 +98,36 @@ int change_memory_attr(unsigned long addr, int numpages, long action)
return apply_to_existing_page_range(&init_mm, start, size,
change_page_attr, (void *)action);
}
+
+/*
+ * Set the attributes of a page:
+ *
+ * This function is used by PPC32 at the end of init to set final kernel memory
+ * protection. It includes changing the maping of the page it is executing from
+ * and data pages it is using.
+ */
+static int set_page_attr(pte_t *ptep, unsigned long addr, void *data)
+{
+ pgprot_t prot = __pgprot((unsigned long)data);
+
+ spin_lock(&init_mm.page_table_lock);
+
+ set_pte_at(&init_mm, addr, ptep, pte_modify(*ptep, prot));
+ flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
+
+ spin_unlock(&init_mm.page_table_lock);
+
+ return 0;
+}
+
+int set_memory_attr(unsigned long addr, int numpages, pgprot_t prot)
+{
+ unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE);
+ unsigned long sz = numpages * PAGE_SIZE;
+
+ if (numpages <= 0)
+ return 0;
+
+ return apply_to_existing_page_range(&init_mm, start, sz, set_page_attr,
+ (void *)pgprot_val(prot));
+}
--
2.25.1
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCH v13 8/8] powerpc/32: use set_memory_attr()
2021-05-10 1:18 [PATCH v13 0/8] powerpc: Further Strict RWX support Jordan Niethe
` (6 preceding siblings ...)
2021-05-10 1:18 ` [PATCH v13 7/8] powerpc/mm: implement set_memory_attr() Jordan Niethe
@ 2021-05-10 1:18 ` Jordan Niethe
7 siblings, 0 replies; 13+ messages in thread
From: Jordan Niethe @ 2021-05-10 1:18 UTC (permalink / raw)
To: linuxppc-dev
Cc: ajd, cmr, npiggin, aneesh.kumar, naveen.n.rao, Jordan Niethe, dja
From: Christophe Leroy <christophe.leroy@csgroup.eu>
Use set_memory_attr() instead of the PPC32 specific change_page_attr()
change_page_attr() was checking that the address was not mapped by
blocks and was handling highmem, but that's unneeded because the
affected pages can't be in highmem and block mapping verification
is already done by the callers.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[ruscur: rebase on powerpc/merge with Christophe's new patches]
Signed-off-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
---
arch/powerpc/mm/pgtable_32.c | 60 ++++++------------------------------
1 file changed, 10 insertions(+), 50 deletions(-)
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index e0ec67a16887..dcf5ecca19d9 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -23,6 +23,7 @@
#include <linux/highmem.h>
#include <linux/memblock.h>
#include <linux/slab.h>
+#include <linux/set_memory.h>
#include <asm/pgalloc.h>
#include <asm/fixmap.h>
@@ -132,64 +133,20 @@ void __init mapin_ram(void)
}
}
-static int __change_page_attr_noflush(struct page *page, pgprot_t prot)
-{
- pte_t *kpte;
- unsigned long address;
-
- BUG_ON(PageHighMem(page));
- address = (unsigned long)page_address(page);
-
- if (v_block_mapped(address))
- return 0;
- kpte = virt_to_kpte(address);
- if (!kpte)
- return -EINVAL;
- __set_pte_at(&init_mm, address, kpte, mk_pte(page, prot), 0);
-
- return 0;
-}
-
-/*
- * Change the page attributes of an page in the linear mapping.
- *
- * THIS DOES NOTHING WITH BAT MAPPINGS, DEBUG USE ONLY
- */
-static int change_page_attr(struct page *page, int numpages, pgprot_t prot)
-{
- int i, err = 0;
- unsigned long flags;
- struct page *start = page;
-
- local_irq_save(flags);
- for (i = 0; i < numpages; i++, page++) {
- err = __change_page_attr_noflush(page, prot);
- if (err)
- break;
- }
- wmb();
- local_irq_restore(flags);
- flush_tlb_kernel_range((unsigned long)page_address(start),
- (unsigned long)page_address(page));
- return err;
-}
-
void mark_initmem_nx(void)
{
- struct page *page = virt_to_page(_sinittext);
unsigned long numpages = PFN_UP((unsigned long)_einittext) -
PFN_DOWN((unsigned long)_sinittext);
if (v_block_mapped((unsigned long)_sinittext))
mmu_mark_initmem_nx();
else
- change_page_attr(page, numpages, PAGE_KERNEL);
+ set_memory_attr((unsigned long)_sinittext, numpages, PAGE_KERNEL);
}
#ifdef CONFIG_STRICT_KERNEL_RWX
void mark_rodata_ro(void)
{
- struct page *page;
unsigned long numpages;
if (v_block_mapped((unsigned long)_stext + 1)) {
@@ -198,20 +155,18 @@ void mark_rodata_ro(void)
return;
}
- page = virt_to_page(_stext);
numpages = PFN_UP((unsigned long)_etext) -
PFN_DOWN((unsigned long)_stext);
- change_page_attr(page, numpages, PAGE_KERNEL_ROX);
+ set_memory_attr((unsigned long)_stext, numpages, PAGE_KERNEL_ROX);
/*
* mark .rodata as read only. Use __init_begin rather than __end_rodata
* to cover NOTES and EXCEPTION_TABLE.
*/
- page = virt_to_page(__start_rodata);
numpages = PFN_UP((unsigned long)__init_begin) -
PFN_DOWN((unsigned long)__start_rodata);
- change_page_attr(page, numpages, PAGE_KERNEL_RO);
+ set_memory_attr((unsigned long)__start_rodata, numpages, PAGE_KERNEL_RO);
// mark_initmem_nx() should have already run by now
ptdump_check_wx();
@@ -221,9 +176,14 @@ void mark_rodata_ro(void)
#ifdef CONFIG_DEBUG_PAGEALLOC
void __kernel_map_pages(struct page *page, int numpages, int enable)
{
+ unsigned long addr = (unsigned long)page_address(page);
+
if (PageHighMem(page))
return;
- change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0));
+ if (enable)
+ set_memory_attr(addr, numpages, PAGE_KERNEL);
+ else
+ set_memory_attr(addr, numpages, __pgprot(0));
}
#endif /* CONFIG_DEBUG_PAGEALLOC */
--
2.25.1
^ permalink raw reply related [flat|nested] 13+ messages in thread