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arm64: Implement arch-specific pte_access_permitted()

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commit 6218f96c58 upstream.

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.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Catalin Marinas 2017-10-26 18:36:47 +01:00 committed by Greg Kroah-Hartman
parent c35be33486
commit ecc3c4795b
1 changed files with 14 additions and 0 deletions
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14
arch/arm64/include/asm/pgtable.h
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@ -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);