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From: Jordan Niethe <jniethe5@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: ajd@linux.ibm.com, cmr@codefail.de, npiggin@gmail.com,
	naveen.n.rao@linux.ibm.com, Jordan Niethe <jniethe5@gmail.com>,
	dja@axtens.net
Subject: [PATCH v10 07/10] powerpc: Set ARCH_HAS_STRICT_MODULE_RWX
Date: Tue, 30 Mar 2021 15:51:29 +1100
Message-ID: <20210330045132.722243-8-jniethe5@gmail.com> (raw)
In-Reply-To: <20210330045132.722243-1-jniethe5@gmail.com>

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
---
 arch/powerpc/Kconfig         |  1 +
 arch/powerpc/kernel/module.c | 11 ++++++++---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 4498a27ac9db..97c0c3540bfd 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -137,6 +137,7 @@ 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 f1fb58389d58..d086f5534fac 100644
--- a/arch/powerpc/kernel/module.c
+++ b/arch/powerpc/kernel/module.c
@@ -90,7 +90,12 @@ int module_finalize(const Elf_Ehdr *hdr,
 
 void *module_alloc(unsigned long size)
 {
-	return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END, GFP_KERNEL,
-				    PAGE_KERNEL_EXEC, VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
-				    __builtin_return_address(0));
+	pgprot_t prot = PAGE_KERNEL_EXEC;
+
+	if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
+		prot = PAGE_KERNEL;
+
+	return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
+			GFP_KERNEL, prot, VM_FLUSH_RESET_PERMS,
+			NUMA_NO_NODE, __builtin_return_address(0));
 }
-- 
2.25.1


  parent reply index

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-30  4:51 [PATCH v10 00/10] powerpc: Further Strict RWX support Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 01/10] powerpc/mm: Implement set_memory() routines Jordan Niethe
2021-03-30  5:16   ` Christophe Leroy
2021-04-21  2:51     ` Jordan Niethe
2021-03-31 11:16   ` Michael Ellerman
2021-03-31 12:03     ` Christophe Leroy
2021-04-21  5:03     ` Jordan Niethe
2021-04-01  4:37   ` Aneesh Kumar K.V
2021-04-21  5:19     ` Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 02/10] powerpc/lib/code-patching: Set up Strict RWX patching earlier Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 03/10] powerpc: Always define MODULES_{VADDR,END} Jordan Niethe
2021-03-30  5:00   ` Christophe Leroy
2021-04-01 13:36   ` Christophe Leroy
2021-04-21  2:46     ` Jordan Niethe
2021-04-21  5:14       ` Christophe Leroy
2021-04-21  5:22         ` Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 04/10] powerpc/kprobes: Mark newly allocated probes as ROX Jordan Niethe
2021-03-30  5:05   ` Christophe Leroy
2021-04-21  2:39     ` Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 05/10] powerpc/bpf: Write protect JIT code Jordan Niethe
2021-03-31 10:37   ` Michael Ellerman
2021-03-31 10:39     ` Christophe Leroy
2021-04-21  2:35     ` Jordan Niethe
2021-04-21  6:51       ` Michael Ellerman
2021-03-30  4:51 ` [PATCH v10 06/10] powerpc/mm/ptdump: debugfs handler for W+X checks at runtime Jordan Niethe
2021-03-31 11:24   ` Michael Ellerman
2021-04-21  2:23     ` Jordan Niethe
2021-04-21  5:16       ` Christophe Leroy
2021-03-30  4:51 ` Jordan Niethe [this message]
2021-03-30  4:51 ` [PATCH v10 08/10] powerpc/configs: Enable STRICT_MODULE_RWX in skiroot_defconfig Jordan Niethe
2021-03-30  5:27   ` Christophe Leroy
2021-04-21  2:37     ` Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 09/10] powerpc/mm: implement set_memory_attr() Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 10/10] powerpc/32: use set_memory_attr() Jordan Niethe

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