Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 8018307a authored by Borislav Petkov's avatar Borislav Petkov Committed by Greg Kroah-Hartman
Browse files

x86/kaiser: Check boottime cmdline params 




AMD (and possibly other vendors) are not affected by the leak
KAISER is protecting against.

Keep the "nopti" for traditional reasons and add pti=<on|off|auto>
like upstream.

Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 50624dd1

Documentation/kernel-parameters.txt

+6 −0
Original line number Diff line number Diff line
@@ -3327,6 +3327,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 
	pt.		[PARIDE]

			See Documentation/blockdev/paride.txt.



	pti=		[X86_64]

			Control KAISER user/kernel address space isolation:

			on - enable

			off - disable

			auto - default setting



	pty.legacy_count=

			[KNL] Number of legacy pty's. Overwrites compiled-in

			default number.

arch/x86/mm/kaiser.c

+41 −18
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <asm/pgtable.h>

#include <asm/pgalloc.h>

#include <asm/desc.h>

#include <asm/cmdline.h>



int kaiser_enabled __read_mostly = 1;

EXPORT_SYMBOL(kaiser_enabled);	/* for inlined TLB flush functions */
@@ -263,6 +264,43 @@ static void __init kaiser_init_all_pgds(void) 
	WARN_ON(__ret);							\

} while (0)



void __init kaiser_check_boottime_disable(void)

{

	bool enable = true;

	char arg[5];

	int ret;



	ret = cmdline_find_option(boot_command_line, "pti", arg, sizeof(arg));

	if (ret > 0) {

		if (!strncmp(arg, "on", 2))

			goto enable;



		if (!strncmp(arg, "off", 3))

			goto disable;



		if (!strncmp(arg, "auto", 4))

			goto skip;

	}



	if (cmdline_find_option_bool(boot_command_line, "nopti"))

		goto disable;



skip:

	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)

		goto disable;



enable:

	if (enable)

		setup_force_cpu_cap(X86_FEATURE_KAISER);



	return;



disable:

	pr_info("Kernel/User page tables isolation: disabled\n");

	kaiser_enabled = 0;

	setup_clear_cpu_cap(X86_FEATURE_KAISER);

}



/*

 * If anything in here fails, we will likely die on one of the

 * first kernel->user transitions and init will die.  But, we
@@ -274,12 +312,10 @@ void __init kaiser_init(void) 
{

	int cpu;



	if (!kaiser_enabled) {

		setup_clear_cpu_cap(X86_FEATURE_KAISER);

		return;

	}

	kaiser_check_boottime_disable();



	setup_force_cpu_cap(X86_FEATURE_KAISER);

	if (!kaiser_enabled)

		return;



	kaiser_init_all_pgds();
@@ -423,16 +459,3 @@ void kaiser_flush_tlb_on_return_to_user(void) 
			X86_CR3_PCID_USER_FLUSH | KAISER_SHADOW_PGD_OFFSET);

}

EXPORT_SYMBOL(kaiser_flush_tlb_on_return_to_user);
 


static int __init x86_nokaiser_setup(char *s)

{

	/* nopti doesn't accept parameters */

	if (s)

		return -EINVAL;



	kaiser_enabled = 0;

	pr_info("Kernel/User page tables isolation: disabled\n");



	return 0;

}

early_param("nopti", x86_nokaiser_setup);