Messages in this thread Patch in this message | | | Subject | Re: [PATCH 1/4] arm64: module: create module allocations without exec permissions | From | Ard Biesheuvel <> | Date | Tue, 28 May 2019 08:24:50 +0200 |
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On 5/28/19 7:35 AM, Anshuman Khandual wrote: > > > On 05/23/2019 03:52 PM, Ard Biesheuvel wrote: >> Now that the core code manages the executable permissions of code >> regions of modules explicitly, it is no longer necessary to create > > I guess the permission transition for various module sections happen > through module_enable_[ro|nx]() after allocating via module_alloc(). >
Indeed.
>> the module vmalloc regions with RWX permissions, and we can create >> them with RW- permissions instead, which is preferred from a >> security perspective. > > Makes sense. Will this be followed in all architectures now ? >
I am not sure if every architecture implements module_enable_[ro|nx](), but if they do, they should probably apply this change as well.
>> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@arm.com> >> --- >> arch/arm64/kernel/module.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c >> index 2e4e3915b4d0..88f0ed31d9aa 100644 >> --- a/arch/arm64/kernel/module.c >> +++ b/arch/arm64/kernel/module.c >> @@ -41,7 +41,7 @@ void *module_alloc(unsigned long size) >> >> p = __vmalloc_node_range(size, MODULE_ALIGN, module_alloc_base, >> module_alloc_base + MODULES_VSIZE, >> - gfp_mask, PAGE_KERNEL_EXEC, 0, >> + gfp_mask, PAGE_KERNEL, 0, >> NUMA_NO_NODE, __builtin_return_address(0)); >> >> if (!p && IS_ENABLED(CONFIG_ARM64_MODULE_PLTS) && >> @@ -57,7 +57,7 @@ void *module_alloc(unsigned long size) >> */ >> p = __vmalloc_node_range(size, MODULE_ALIGN, module_alloc_base, >> module_alloc_base + SZ_4G, GFP_KERNEL, >> - PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE, >> + PAGE_KERNEL, 0, NUMA_NO_NODE, >> __builtin_return_address(0)); >> >> if (p && (kasan_module_alloc(p, size) < 0)) { >> > > Which just makes sure that PTE_PXN never gets dropped while creating > these mappings. >
Not sure what you mean. Is there a question here?
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