Commit 8c479c2c authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'hardened-usercopy-v4.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux 

Pull hardened usercopy updates from Kees Cook:
 "This cleans up a minor Kconfig issue and adds a kernel boot option for
  disabling hardened usercopy for distro users that may have corner-case
  performance issues (e.g. high bandwidth small-packet UDP traffic).

  Summary:

   - drop unneeded Kconfig "select BUG" (Kamal Mostafa)

   - add "hardened_usercopy=off" rare performance needs (Chris von
     Recklinghausen)"

* tag 'hardened-usercopy-v4.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  usercopy: Allow boot cmdline disabling of hardening
  usercopy: Do not select BUG with HARDENED_USERCOPY
parents 31130a16 b5cb15d9

Documentation/admin-guide/kernel-parameters.txt

+11 −0
Original line number Diff line number Diff line
@@ -816,6 +816,17 @@ 
	disable=	[IPV6]

			See Documentation/networking/ipv6.txt.



	hardened_usercopy=

                        [KNL] Under CONFIG_HARDENED_USERCOPY, whether

                        hardening is enabled for this boot. Hardened

                        usercopy checking is used to protect the kernel

                        from reading or writing beyond known memory

                        allocation boundaries as a proactive defense

                        against bounds-checking flaws in the kernel's

                        copy_to_user()/copy_from_user() interface.

                on      Perform hardened usercopy checks (default).

                off     Disable hardened usercopy checks.



	disable_radix	[PPC]

			Disable RADIX MMU mode on POWER9

include/linux/jump_label.h

+6 −0
Original line number Diff line number Diff line
@@ -299,12 +299,18 @@ struct static_key_false { 
#define DEFINE_STATIC_KEY_TRUE(name)	\

	struct static_key_true name = STATIC_KEY_TRUE_INIT



#define DEFINE_STATIC_KEY_TRUE_RO(name)	\

	struct static_key_true name __ro_after_init = STATIC_KEY_TRUE_INIT



#define DECLARE_STATIC_KEY_TRUE(name)	\

	extern struct static_key_true name



#define DEFINE_STATIC_KEY_FALSE(name)	\

	struct static_key_false name = STATIC_KEY_FALSE_INIT



#define DEFINE_STATIC_KEY_FALSE_RO(name)	\

	struct static_key_false name __ro_after_init = STATIC_KEY_FALSE_INIT



#define DECLARE_STATIC_KEY_FALSE(name)	\

	extern struct static_key_false name

mm/usercopy.c

+25 −0
Original line number Diff line number Diff line
@@ -20,6 +20,8 @@ 
#include <linux/sched/task.h>

#include <linux/sched/task_stack.h>

#include <linux/thread_info.h>

#include <linux/atomic.h>

#include <linux/jump_label.h>

#include <asm/sections.h>



/*
@@ -240,6 +242,8 @@ static inline void check_heap_object(const void *ptr, unsigned long n, 
	}

}



static DEFINE_STATIC_KEY_FALSE_RO(bypass_usercopy_checks);



/*

 * Validates that the given object is:

 * - not bogus address
@@ -248,6 +252,9 @@ static inline void check_heap_object(const void *ptr, unsigned long n, 
 */

void __check_object_size(const void *ptr, unsigned long n, bool to_user)

{

	if (static_branch_unlikely(&bypass_usercopy_checks))

		return;



	/* Skip all tests if size is zero. */

	if (!n)

		return;
@@ -279,3 +286,21 @@ void __check_object_size(const void *ptr, unsigned long n, bool to_user) 
	check_kernel_text_object((const unsigned long)ptr, n, to_user);

}

EXPORT_SYMBOL(__check_object_size);



static bool enable_checks __initdata = true;



static int __init parse_hardened_usercopy(char *str)

{

	return strtobool(str, &enable_checks);

}



__setup("hardened_usercopy=", parse_hardened_usercopy);



static int __init set_hardened_usercopy(void)

{

	if (enable_checks == false)

		static_branch_enable(&bypass_usercopy_checks);

	return 1;

}



late_initcall(set_hardened_usercopy);

security/Kconfig

+0 −1
Original line number Diff line number Diff line
@@ -153,7 +153,6 @@ config HAVE_HARDENED_USERCOPY_ALLOCATOR 
config HARDENED_USERCOPY

	bool "Harden memory copies between kernel and userspace"

	depends on HAVE_HARDENED_USERCOPY_ALLOCATOR

	select BUG

	imply STRICT_DEVMEM

	help

	  This option checks for obviously wrong memory regions when

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