From: Sai Praneeth Date: Tue, 31 Jan 2017 13:21:37 +0000 (+0000) Subject: x86/efi: Add support for EFI_MEMORY_ATTRIBUTES_TABLE X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=18141e89a76c58101860486fd9cc0999da2eed43;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git x86/efi: Add support for EFI_MEMORY_ATTRIBUTES_TABLE UEFI v2.6 introduces EFI_MEMORY_ATTRIBUTES_TABLE which describes memory protections that may be applied to the EFI Runtime code and data regions by the kernel. This enables the kernel to map these regions more strictly thereby increasing security. Presently, the only valid bits for the attribute field of a memory descriptor are EFI_MEMORY_RO and EFI_MEMORY_XP, hence use these bits to update the mappings in efi_pgd. The UEFI specification recommends to use this feature instead of EFI_PROPERTIES_TABLE and hence while updating EFI mappings we first check for EFI_MEMORY_ATTRIBUTES_TABLE and if it's present we update the mappings according to this table and hence disregarding EFI_PROPERTIES_TABLE even if it's published by the firmware. We consider EFI_PROPERTIES_TABLE only when EFI_MEMORY_ATTRIBUTES_TABLE is absent. Signed-off-by: Sai Praneeth Prakhya Signed-off-by: Matt Fleming Signed-off-by: Ard Biesheuvel Cc: Borislav Petkov Cc: Fenghua Yu Cc: Lee, Chun-Yi Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Ravi Shankar Cc: Ricardo Neri Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1485868902-20401-6-git-send-email-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index 2f25a363068c..a4695da42d77 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -414,10 +414,44 @@ void __init parse_efi_setup(u64 phys_addr, u32 data_len) efi_setup = phys_addr + sizeof(struct setup_data); } -void __init efi_runtime_update_mappings(void) +static int __init efi_update_mappings(efi_memory_desc_t *md, unsigned long pf) { unsigned long pfn; pgd_t *pgd = efi_pgd; + int err1, err2; + + /* Update the 1:1 mapping */ + pfn = md->phys_addr >> PAGE_SHIFT; + err1 = kernel_map_pages_in_pgd(pgd, pfn, md->phys_addr, md->num_pages, pf); + if (err1) { + pr_err("Error while updating 1:1 mapping PA 0x%llx -> VA 0x%llx!\n", + md->phys_addr, md->virt_addr); + } + + err2 = kernel_map_pages_in_pgd(pgd, pfn, md->virt_addr, md->num_pages, pf); + if (err2) { + pr_err("Error while updating VA mapping PA 0x%llx -> VA 0x%llx!\n", + md->phys_addr, md->virt_addr); + } + + return err1 || err2; +} + +static int __init efi_update_mem_attr(struct mm_struct *mm, efi_memory_desc_t *md) +{ + unsigned long pf = 0; + + if (md->attribute & EFI_MEMORY_XP) + pf |= _PAGE_NX; + + if (!(md->attribute & EFI_MEMORY_RO)) + pf |= _PAGE_RW; + + return efi_update_mappings(md, pf); +} + +void __init efi_runtime_update_mappings(void) +{ efi_memory_desc_t *md; if (efi_enabled(EFI_OLD_MEMMAP)) { @@ -426,6 +460,24 @@ void __init efi_runtime_update_mappings(void) return; } + /* + * Use the EFI Memory Attribute Table for mapping permissions if it + * exists, since it is intended to supersede EFI_PROPERTIES_TABLE. + */ + if (efi_enabled(EFI_MEM_ATTR)) { + efi_memattr_apply_permissions(NULL, efi_update_mem_attr); + return; + } + + /* + * EFI_MEMORY_ATTRIBUTES_TABLE is intended to replace + * EFI_PROPERTIES_TABLE. So, use EFI_PROPERTIES_TABLE to update + * permissions only if EFI_MEMORY_ATTRIBUTES_TABLE is not + * published by the firmware. Even if we find a buggy implementation of + * EFI_MEMORY_ATTRIBUTES_TABLE, don't fall back to + * EFI_PROPERTIES_TABLE, because of the same reason. + */ + if (!efi_enabled(EFI_NX_PE_DATA)) return; @@ -446,15 +498,7 @@ void __init efi_runtime_update_mappings(void) (md->type != EFI_RUNTIME_SERVICES_CODE)) pf |= _PAGE_RW; - /* Update the 1:1 mapping */ - pfn = md->phys_addr >> PAGE_SHIFT; - if (kernel_map_pages_in_pgd(pgd, pfn, md->phys_addr, md->num_pages, pf)) - pr_warn("Error mapping PA 0x%llx -> VA 0x%llx!\n", - md->phys_addr, md->virt_addr); - - if (kernel_map_pages_in_pgd(pgd, pfn, md->virt_addr, md->num_pages, pf)) - pr_warn("Error mapping PA 0x%llx -> VA 0x%llx!\n", - md->phys_addr, md->virt_addr); + efi_update_mappings(md, pf); } } diff --git a/drivers/firmware/efi/memattr.c b/drivers/firmware/efi/memattr.c index 402197460507..8986757eafaf 100644 --- a/drivers/firmware/efi/memattr.c +++ b/drivers/firmware/efi/memattr.c @@ -175,8 +175,11 @@ int __init efi_memattr_apply_permissions(struct mm_struct *mm, md.phys_addr + size - 1, efi_md_typeattr_format(buf, sizeof(buf), &md)); - if (valid) + if (valid) { ret = fn(mm, &md); + if (ret) + pr_err("Error updating mappings, skipping subsequent md's\n"); + } } memunmap(tbl); return ret;