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

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
......@@ -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
......
......@@ -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
......
......@@ -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);
......@@ -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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