[PATCH v5 14/25] arm64: mte: Validate the PROT_MTE request via arch_validate_flags()
From: Catalin Marinas <catalin.marinas@arm.com>
Date: 2020-06-24 17:53:25
Also in:
linux-arch, linux-mm
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
Make use of the newly introduced arch_validate_flags() hook to sanity-check the PROT_MTE request passed to mmap() and mprotect(). If the mapping does not support MTE, these syscalls will return -EINVAL. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> --- arch/arm64/include/asm/mman.h | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/mman.h b/arch/arm64/include/asm/mman.h
index b01051be7750..e3e28f7daf62 100644
--- a/arch/arm64/include/asm/mman.h
+++ b/arch/arm64/include/asm/mman.h@@ -49,8 +49,10 @@ static inline pgprot_t arch_vm_get_page_prot(unsigned long vm_flags) * register (1) as VM_MTE in the vma->vm_flags and (2) as * VM_MTE_ALLOWED. Note that the latter can only be set during the * mmap() call since mprotect() does not accept MAP_* flags. + * Checking for VM_MTE only is sufficient since arch_validate_flags() + * does not permit (VM_MTE & !VM_MTE_ALLOWED). */ - if ((vm_flags & VM_MTE) && (vm_flags & VM_MTE_ALLOWED)) + if (vm_flags & VM_MTE) prot |= PTE_ATTRINDX(MT_NORMAL_TAGGED); return __pgprot(prot);
@@ -72,4 +74,14 @@ static inline bool arch_validate_prot(unsigned long prot, } #define arch_validate_prot(prot, addr) arch_validate_prot(prot, addr) +static inline bool arch_validate_flags(unsigned long vm_flags) +{ + if (!system_supports_mte()) + return true; + + /* only allow VM_MTE if VM_MTE_ALLOWED has been set previously */ + return !(vm_flags & VM_MTE) || (vm_flags & VM_MTE_ALLOWED); +} +#define arch_validate_flags(vm_flags) arch_validate_flags(vm_flags) + #endif /* ! __ASM_MMAN_H__ */
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