arm64: Implement arch-specific pte_access_permitted() (6218f96c) · Commits · 戴 / test

The generic pte_access_permitted() implementation only checks for pte_present() (together with the write permission where applicable). However, for both kernel ptes and PROT_NONE mappings pte_present() also returns true on arm64 even though such mappings are not user accessible. Additionally, arm64 now supports execute-only user permission (PROT_EXEC) which is implemented by clearing the PTE_USER bit. With this patch the arm64 implementation of pte_access_permitted() checks for the PTE_VALID and PTE_USER bits together with writable access if applicable. Cc: <stable@vger.kernel.org> Reported-by:

Al Viro <viro@zeniv.linux.org.uk> Signed-off-by:

Catalin Marinas <catalin.marinas@arm.com> Signed-off-by:

Will Deacon <will.deacon@arm.com>

arch/arm64/include/asm/pgtable.h

+14 −0

Original line number	Diff line number	Diff line
		@@ -98,6 +98,8 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
		((pte_val(pte) & (PTE_VALID \| PTE_USER \| PTE_UXN)) == (PTE_VALID \| PTE_UXN))
		#define pte_valid_young(pte) \
		((pte_val(pte) & (PTE_VALID \| PTE_AF)) == (PTE_VALID \| PTE_AF))
		#define pte_valid_user(pte) \
		((pte_val(pte) & (PTE_VALID \| PTE_USER)) == (PTE_VALID \| PTE_USER))

		/*
		* Could the pte be present in the TLB? We must check mm_tlb_flush_pending
		@@ -107,6 +109,18 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
		#define pte_accessible(mm, pte) \
		(mm_tlb_flush_pending(mm) ? pte_present(pte) : pte_valid_young(pte))

		/*
		* p??_access_permitted() is true for valid user mappings (subject to the
		* write permission check) other than user execute-only which do not have the
		* PTE_USER bit set. PROT_NONE mappings do not have the PTE_VALID bit set.
		*/
		#define pte_access_permitted(pte, write) \
		(pte_valid_user(pte) && (!(write) \|\| pte_write(pte)))
		#define pmd_access_permitted(pmd, write) \
		(pte_access_permitted(pmd_pte(pmd), (write)))
		#define pud_access_permitted(pud, write) \
		(pte_access_permitted(pud_pte(pud), (write)))

		static inline pte_t clear_pte_bit(pte_t pte, pgprot_t prot)
		{
		pte_val(pte) &= ~pgprot_val(prot);

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