diff --git a/README.md b/README.md index c1809bc..8dd86fc 100644 --- a/README.md +++ b/README.md @@ -224,9 +224,6 @@ Kernel space: - Enable the kernel page allocator to randomize free lists to limit some data exfiltration and ROP attacks, especially during the early boot process. -- Enable kernel page table isolation on x86_64 and ARM64 CPUs to increase - KASLR effectiveness and also mitigate the Meltdown CPU vulnerability. - - Enable randomization of the kernel stack offset on syscall entries to harden against memory corruption attacks. diff --git a/etc/default/grub.d/40_cpu_mitigations.cfg#security-misc-shared b/etc/default/grub.d/40_cpu_mitigations.cfg#security-misc-shared index 10f3af0..7df65d0 100644 --- a/etc/default/grub.d/40_cpu_mitigations.cfg#security-misc-shared +++ b/etc/default/grub.d/40_cpu_mitigations.cfg#security-misc-shared @@ -83,17 +83,18 @@ GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX spectre_bhi=on" ## Meltdown: ## Mitigate Spectre Variant 3 using kernel page table isolation (PTI). -## Force enable PTI of user and kernel address spaces on all cores. -## Mitigations for X86_64 CPUs are done in /etc/default/grub.d/40_kernel_hardening.cfg using "pti=on". -## Currently affects ARM64 CPUs. +## Enables kernel PTI to harden against kernel ASLR (KASLR) bypasses. +## Force enables PTI of user and kernel address spaces on all ARM cores. +## Currently affects AMD, ARM64, and Intel CPUs. ## ## https://en.wikipedia.org/wiki/Meltdown_(security_vulnerability) ## https://en.wikipedia.org/wiki/Kernel_page-table_isolation ## ## KSPP=yes -## KSPP sets CONFIG_UNMAP_KERNEL_AT_EL0=y. +## KSPP sets the second kernel parameter, CONFIG_MITIGATION_PAGE_TABLE_ISOLATION=y, and CONFIG_UNMAP_KERNEL_AT_EL0=y. ## GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX kpti=1" +GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX pti=on" ## Speculative Store Bypass (SSB): ## Mitigate Spectre Variant 4 by disabling speculative store bypass system-wide. diff --git a/etc/default/grub.d/40_kernel_hardening.cfg#security-misc-shared b/etc/default/grub.d/40_kernel_hardening.cfg#security-misc-shared index 7f9cabe..861c986 100644 --- a/etc/default/grub.d/40_kernel_hardening.cfg#security-misc-shared +++ b/etc/default/grub.d/40_kernel_hardening.cfg#security-misc-shared @@ -86,18 +86,6 @@ GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX init_on_free=1" ## GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX page_alloc.shuffle=1" -## Enable kernel page table isolation to harden against kernel ASLR (KASLR) bypasses. -## Mitigates the Meltdown (Spectre Variant 3) CPU vulnerability. -## Mitigations for ARM64 CPUs are done in /etc/default/grub.d/40_cpu_mitigations.cfg using "kpti=1". -## -## https://en.wikipedia.org/wiki/Meltdown_(security_vulnerability) -## https://en.wikipedia.org/wiki/Kernel_page-table_isolation -## -## KSPP=yes -## KSPP sets the kernel parameter and CONFIG_MITIGATION_PAGE_TABLE_ISOLATION=y. -## -GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX pti=on" - ## Enable randomization of the kernel stack offset on syscall entries. ## Hardens against memory corruption attacks due to increased entropy. ## Limits attacks relying on deterministic stack addresses or cross-syscall address exposure.