Re: [PATCH v14 3/9] powerpc/modules: Make module_alloc() Strict Module RWX aware
From: Christophe Leroy <hidden>
Date: 2021-05-17 06:38:20
Le 17/05/2021 à 05:28, Jordan Niethe a écrit :
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Make module_alloc() use PAGE_KERNEL protections instead of PAGE_KERNEL_EXEX if Strict Module RWX is enabled. Signed-off-by: Jordan Niethe <redacted> --- v14: - Split out from powerpc: Set ARCH_HAS_STRICT_MODULE_RWX - Add and use strict_module_rwx_enabled() helper --- arch/powerpc/include/asm/mmu.h | 5 +++++ arch/powerpc/kernel/module.c | 4 +++- 2 files changed, 8 insertions(+), 1 deletion(-)diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h index 607168b1aef4..7710bf0cbf8a 100644 --- a/arch/powerpc/include/asm/mmu.h +++ b/arch/powerpc/include/asm/mmu.h@@ -357,6 +357,11 @@ static inline bool strict_kernel_rwx_enabled(void) return false; } #endif + +static inline bool strict_module_rwx_enabled(void) +{ + return IS_ENABLED(CONFIG_STRICT_MODULE_RWX) && strict_kernel_rwx_enabled(); +}
Looking at arch/Kconfig, I have the feeling that it is possible to select CONFIG_STRICT_MODULE_RWX without selecting CONFIG_STRICT_KERNEL_RWX. In that case, strict_kernel_rwx_enabled() will return false.
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#endif /* !__ASSEMBLY__ */ /* The kernel use the constants below to index in the page sizes array.diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c index 3f35c8d20be7..ed04a3ba66fe 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_module_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)); }