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author | Vladimir Murzin <vladimir.murzin@arm.com> | 2021-03-12 20:38:10 +0300 |
---|---|---|
committer | Catalin Marinas <catalin.marinas@arm.com> | 2021-03-26 12:37:23 +0300 |
commit | 18107f8a2df6bf1c6cac8d0713f757f866d5af51 (patch) | |
tree | 0411230b8d6c259233a6aadcd0c0aaf261b86c2a /arch/arm64/include/asm/pgtable.h | |
parent | 1e28eed17697bcf343c6743f0028cc3b5dd88bf0 (diff) | |
download | linux-18107f8a2df6bf1c6cac8d0713f757f866d5af51.tar.xz |
arm64: Support execute-only permissions with Enhanced PAN
Enhanced Privileged Access Never (EPAN) allows Privileged Access Never
to be used with Execute-only mappings.
Absence of such support was a reason for 24cecc377463 ("arm64: Revert
support for execute-only user mappings"). Thus now it can be revisited
and re-enabled.
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210312173811.58284-2-vladimir.murzin@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/include/asm/pgtable.h')
-rw-r--r-- | arch/arm64/include/asm/pgtable.h | 31 |
1 files changed, 23 insertions, 8 deletions
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 47027796c2f9..0b10204e72fc 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -113,11 +113,12 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]; #define pte_dirty(pte) (pte_sw_dirty(pte) || pte_hw_dirty(pte)) #define pte_valid(pte) (!!(pte_val(pte) & PTE_VALID)) +/* + * Execute-only user mappings do not have the PTE_USER bit set. All valid + * kernel mappings have the PTE_UXN bit set. + */ #define pte_valid_not_user(pte) \ - ((pte_val(pte) & (PTE_VALID | PTE_USER)) == PTE_VALID) -#define pte_valid_user(pte) \ - ((pte_val(pte) & (PTE_VALID | PTE_USER)) == (PTE_VALID | PTE_USER)) - + ((pte_val(pte) & (PTE_VALID | PTE_USER | PTE_UXN)) == (PTE_VALID | PTE_UXN)) /* * Could the pte be present in the TLB? We must check mm_tlb_flush_pending * so that we don't erroneously return false for pages that have been @@ -130,12 +131,14 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]; (mm_tlb_flush_pending(mm) ? pte_present(pte) : pte_valid(pte)) /* - * p??_access_permitted() is true for valid user mappings (subject to the - * write permission check). PROT_NONE mappings do not have the PTE_VALID bit - * set. + * p??_access_permitted() is true for valid user mappings (PTE_USER + * bit set, subject to the write permission check). For execute-only + * mappings, like PROT_EXEC with EPAN (both PTE_USER and PTE_UXN bits + * not set) must return false. 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))) + (((pte_val(pte) & (PTE_VALID | PTE_USER)) == (PTE_VALID | PTE_USER)) && (!(write) || pte_write(pte))) #define pmd_access_permitted(pmd, write) \ (pte_access_permitted(pmd_pte(pmd), (write))) #define pud_access_permitted(pud, write) \ @@ -995,6 +998,18 @@ static inline bool arch_wants_old_prefaulted_pte(void) } #define arch_wants_old_prefaulted_pte arch_wants_old_prefaulted_pte +static inline pgprot_t arch_filter_pgprot(pgprot_t prot) +{ + if (cpus_have_const_cap(ARM64_HAS_EPAN)) + return prot; + + if (pgprot_val(prot) != pgprot_val(PAGE_EXECONLY)) + return prot; + + return PAGE_READONLY_EXEC; +} + + #endif /* !__ASSEMBLY__ */ #endif /* __ASM_PGTABLE_H */ |