Messages in this thread Patch in this message | | | Date | Tue, 17 Mar 2020 14:57:21 -0000 | From | "tip-bot2 for Thomas Hellstrom" <> | Subject | [tip: x86/mm] x86: Don't let pgprot_modify() change the page encryption bit |
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The following commit has been merged into the x86/mm branch of tip:
Commit-ID: 6db73f17c5f155dbcfd5e48e621c706270b84df0 Gitweb: https://git.kernel.org/tip/6db73f17c5f155dbcfd5e48e621c706270b84df0 Author: Thomas Hellstrom <thellstrom@vmware.com> AuthorDate: Wed, 04 Mar 2020 12:45:26 +01:00 Committer: Borislav Petkov <bp@suse.de> CommitterDate: Tue, 17 Mar 2020 11:48:31 +01:00
x86: Don't let pgprot_modify() change the page encryption bit
When SEV or SME is enabled and active, vm_get_page_prot() typically returns with the encryption bit set. This means that users of pgprot_modify(, vm_get_page_prot()) (mprotect_fixup(), do_mmap()) end up with a value of vma->vm_pg_prot that is not consistent with the intended protection of the PTEs.
This is also important for fault handlers that rely on the VMA vm_page_prot to set the page protection. Fix this by not allowing pgprot_modify() to change the encryption bit, similar to how it's done for PAT bits.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lkml.kernel.org/r/20200304114527.3636-2-thomas_os@shipmail.org --- arch/x86/include/asm/pgtable.h | 7 +++++-- arch/x86/include/asm/pgtable_types.h | 2 +- 2 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 7e11866..64a03f2 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -627,12 +627,15 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot) return __pmd(val); } -/* mprotect needs to preserve PAT bits when updating vm_page_prot */ +/* + * mprotect needs to preserve PAT and encryption bits when updating + * vm_page_prot + */ #define pgprot_modify pgprot_modify static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot) { pgprotval_t preservebits = pgprot_val(oldprot) & _PAGE_CHG_MASK; - pgprotval_t addbits = pgprot_val(newprot); + pgprotval_t addbits = pgprot_val(newprot) & ~_PAGE_CHG_MASK; return __pgprot(preservebits | addbits); } diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h index 0239998..65c2ecd 100644 --- a/arch/x86/include/asm/pgtable_types.h +++ b/arch/x86/include/asm/pgtable_types.h @@ -118,7 +118,7 @@ */ #define _PAGE_CHG_MASK (PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT | \ _PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY | \ - _PAGE_SOFT_DIRTY | _PAGE_DEVMAP) + _PAGE_SOFT_DIRTY | _PAGE_DEVMAP | _PAGE_ENC) #define _HPAGE_CHG_MASK (_PAGE_CHG_MASK | _PAGE_PSE) /*
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