From: Borislav Petkov Date: Thu, 27 Jan 2022 11:56:25 +0000 (+0100) Subject: x86/cpu: Remove "noexec" X-Git-Tag: v6.6.17~6984^2~8 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=76ea0025a214cdf0d2c204f4c21cbffa9fb57c32;p=platform%2Fkernel%2Flinux-rpi.git x86/cpu: Remove "noexec" It doesn't make any sense to disable non-executable mappings - security-wise or else. So rip out that switch and move the remaining code into setup.c and delete setup_nx.c Signed-off-by: Borislav Petkov Reviewed-by: Lai Jiangshan Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20220127115626.14179-6-bp@alien8.de --- diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 39ac2c1..a2299b2 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3456,11 +3456,6 @@ noexec [IA-64] - noexec [X86] - On X86-32 available only on PAE configured kernels. - noexec=on: enable non-executable mappings (default) - noexec=off: disable non-executable mappings - nosmap [PPC] Disable SMAP (Supervisor Mode Access Prevention) even if it is supported by processor. diff --git a/Documentation/x86/x86_64/boot-options.rst b/Documentation/x86/x86_64/boot-options.rst index 07aa000..fb6030a 100644 --- a/Documentation/x86/x86_64/boot-options.rst +++ b/Documentation/x86/x86_64/boot-options.rst @@ -157,15 +157,6 @@ Rebooting newer BIOS, or newer board) using this option will ignore the built-in quirk table, and use the generic default reboot actions. -Non Executable Mappings -======================= - - noexec=on|off - on - Enable(default) - off - Disable - NUMA ==== diff --git a/arch/x86/include/asm/proto.h b/arch/x86/include/asm/proto.h index feed36d..0f899c8 100644 --- a/arch/x86/include/asm/proto.h +++ b/arch/x86/include/asm/proto.h @@ -35,7 +35,6 @@ void xen_entry_INT80_compat(void); #endif void x86_configure_nx(void); -void x86_report_nx(void); extern int reboot_force; diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index c95b9ac..249981b 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -756,6 +756,30 @@ dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p) return 0; } +void x86_configure_nx(void) +{ + if (boot_cpu_has(X86_FEATURE_NX)) + __supported_pte_mask |= _PAGE_NX; + else + __supported_pte_mask &= ~_PAGE_NX; +} + +static void __init x86_report_nx(void) +{ + if (!boot_cpu_has(X86_FEATURE_NX)) { + printk(KERN_NOTICE "Notice: NX (Execute Disable) protection " + "missing in CPU!\n"); + } else { +#if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE) + printk(KERN_INFO "NX (Execute Disable) protection: active\n"); +#else + /* 32bit non-PAE kernel, NX cannot be used */ + printk(KERN_NOTICE "Notice: NX (Execute Disable) protection " + "cannot be enabled: non-PAE kernel!\n"); +#endif + } +} + /* * Determine if we were loaded by an EFI loader. If so, then we have also been * passed the efi memmap, systab, etc., so we should use these data structures @@ -896,9 +920,7 @@ void __init setup_arch(char **cmdline_p) /* * x86_configure_nx() is called before parse_early_param() to detect * whether hardware doesn't support NX (so that the early EHCI debug - * console setup can safely call set_fixmap()). It may then be called - * again from within noexec_setup() during parsing early parameters - * to honor the respective command line option. + * console setup can safely call set_fixmap()). */ x86_configure_nx(); diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile index fe3d306..d957dc1 100644 --- a/arch/x86/mm/Makefile +++ b/arch/x86/mm/Makefile @@ -20,13 +20,12 @@ CFLAGS_REMOVE_mem_encrypt_identity.o = -pg endif obj-y := init.o init_$(BITS).o fault.o ioremap.o extable.o mmap.o \ - pgtable.o physaddr.o setup_nx.o tlb.o cpu_entry_area.o maccess.o + pgtable.o physaddr.o tlb.o cpu_entry_area.o maccess.o obj-y += pat/ # Make sure __phys_addr has no stackprotector CFLAGS_physaddr.o := -fno-stack-protector -CFLAGS_setup_nx.o := -fno-stack-protector CFLAGS_mem_encrypt_identity.o := -fno-stack-protector CFLAGS_fault.o := -I $(srctree)/$(src)/../include/asm/trace diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 96d34eb..d2e484e 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -110,7 +110,6 @@ int force_personality32; /* * noexec32=on|off * Control non executable heap for 32bit processes. - * To control the stack too use noexec=off * * on PROT_READ does not imply PROT_EXEC for 32-bit processes (default) * off PROT_READ implies PROT_EXEC diff --git a/arch/x86/mm/setup_nx.c b/arch/x86/mm/setup_nx.c deleted file mode 100644 index ed5667f..0000000 --- a/arch/x86/mm/setup_nx.c +++ /dev/null @@ -1,62 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -#include -#include -#include -#include - -#include -#include - -static int disable_nx; - -/* - * noexec = on|off - * - * Control non-executable mappings for processes. - * - * on Enable - * off Disable - */ -static int __init noexec_setup(char *str) -{ - if (!str) - return -EINVAL; - if (!strncmp(str, "on", 2)) { - disable_nx = 0; - } else if (!strncmp(str, "off", 3)) { - disable_nx = 1; - } - x86_configure_nx(); - return 0; -} -early_param("noexec", noexec_setup); - -void x86_configure_nx(void) -{ - if (boot_cpu_has(X86_FEATURE_NX) && !disable_nx) - __supported_pte_mask |= _PAGE_NX; - else - __supported_pte_mask &= ~_PAGE_NX; -} - -void __init x86_report_nx(void) -{ - if (!boot_cpu_has(X86_FEATURE_NX)) { - printk(KERN_NOTICE "Notice: NX (Execute Disable) protection " - "missing in CPU!\n"); - } else { -#if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE) - if (disable_nx) { - printk(KERN_INFO "NX (Execute Disable) protection: " - "disabled by kernel command line option\n"); - } else { - printk(KERN_INFO "NX (Execute Disable) protection: " - "active\n"); - } -#else - /* 32bit non-PAE kernel, NX cannot be used */ - printk(KERN_NOTICE "Notice: NX (Execute Disable) protection " - "cannot be enabled: non-PAE kernel!\n"); -#endif - } -}