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Commit 15385dfe authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'x86-smap-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86/smap support from Ingo Molnar:
 "This adds support for the SMAP (Supervisor Mode Access Prevention) CPU
  feature on Intel CPUs: a hardware feature that prevents unintended
  user-space data access from kernel privileged code.

  It's turned on automatically when possible.

  This, in combination with SMEP, makes it even harder to exploit kernel
  bugs such as NULL pointer dereferences."

Fix up trivial conflict in arch/x86/kernel/entry_64.S due to newly added
includes right next to each other.

* 'x86-smap-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, smep, smap: Make the switching functions one-way
  x86, suspend: On wakeup always initialize cr4 and EFER
  x86-32: Start out eflags and cr4 clean
  x86, smap: Do not abuse the [f][x]rstor_checking() functions for user space
  x86-32, smap: Add STAC/CLAC instructions to 32-bit kernel entry
  x86, smap: Reduce the SMAP overhead for signal handling
  x86, smap: A page fault due to SMAP is an oops
  x86, smap: Turn on Supervisor Mode Access Prevention
  x86, smap: Add STAC and CLAC instructions to control user space access
  x86, uaccess: Merge prototypes for clear_user/__clear_user
  x86, smap: Add a header file with macros for STAC/CLAC
  x86, alternative: Add header guards to <asm/alternative-asm.h>
  x86, alternative: Use .pushsection/.popsection
  x86, smap: Add CR4 bit for SMAP
  x86-32, mm: The WP test should be done on a kernel page
parents a57d985e b2cc2a07

Documentation/kernel-parameters.txt

+5 −1
Original line number Diff line number Diff line
@@ -1812,8 +1812,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 
			noexec=on: enable non-executable mappings (default)

			noexec=off: disable non-executable mappings



	nosmap		[X86]

			Disable SMAP (Supervisor Mode Access Prevention)

			even if it is supported by processor.



	nosmep		[X86]

			Disable SMEP (Supervisor Mode Execution Protection)

			Disable SMEP (Supervisor Mode Execution Prevention)

			even if it is supported by processor.



	noexec32	[X86-64]

arch/x86/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -1493,6 +1493,17 @@ config ARCH_RANDOM 
	  If supported, this is a high bandwidth, cryptographically

	  secure hardware random number generator.



config X86_SMAP

	def_bool y

	prompt "Supervisor Mode Access Prevention" if EXPERT

	---help---

	  Supervisor Mode Access Prevention (SMAP) is a security

	  feature in newer Intel processors.  There is a small

	  performance cost if this enabled and turned on; there is

	  also a small increase in the kernel size if this is enabled.



	  If unsure, say Y.



config EFI

	bool "EFI runtime service support"

	depends on ACPI

arch/x86/ia32/ia32_signal.c

+8 −5
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ 
#include <asm/sigframe.h>

#include <asm/sighandling.h>

#include <asm/sys_ia32.h>

#include <asm/smap.h>



#define FIX_EFLAGS	__FIX_EFLAGS
@@ -251,11 +252,12 @@ static int ia32_restore_sigcontext(struct pt_regs *regs, 


		get_user_ex(tmp, &sc->fpstate);

		buf = compat_ptr(tmp);

		err |= restore_xstate_sig(buf, 1);



		get_user_ex(*pax, &sc->ax);

	} get_user_catch(err);



	err |= restore_xstate_sig(buf, 1);



	return err;

}
@@ -506,7 +508,6 @@ int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 
		put_user_ex(sig, &frame->sig);

		put_user_ex(ptr_to_compat(&frame->info), &frame->pinfo);

		put_user_ex(ptr_to_compat(&frame->uc), &frame->puc);

		err |= copy_siginfo_to_user32(&frame->info, info);



		/* Create the ucontext.  */

		if (cpu_has_xsave)
@@ -518,9 +519,6 @@ int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 
		put_user_ex(sas_ss_flags(regs->sp),

			    &frame->uc.uc_stack.ss_flags);

		put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);

		err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, fpstate,

					     regs, set->sig[0]);

		err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));



		if (ka->sa.sa_flags & SA_RESTORER)

			restorer = ka->sa.sa_restorer;
@@ -536,6 +534,11 @@ int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 
		put_user_ex(*((u64 *)&code), (u64 __user *)frame->retcode);

	} put_user_catch(err);



	err |= copy_siginfo_to_user32(&frame->info, info);

	err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, fpstate,

				     regs, set->sig[0]);

	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));



	if (err)

		return -EFAULT;

arch/x86/ia32/ia32entry.S

+6 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <asm/segment.h>

#include <asm/irqflags.h>

#include <asm/asm.h>

#include <asm/smap.h>

#include <linux/linkage.h>

#include <linux/err.h>
@@ -146,8 +147,10 @@ ENTRY(ia32_sysenter_target) 
	SAVE_ARGS 0,1,0

 	/* no need to do an access_ok check here because rbp has been

 	   32bit zero extended */ 

	ASM_STAC

1:	movl	(%rbp),%ebp

	_ASM_EXTABLE(1b,ia32_badarg)

	ASM_CLAC

	orl     $TS_COMPAT,TI_status+THREAD_INFO(%rsp,RIP-ARGOFFSET)

	testl   $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET)

	CFI_REMEMBER_STATE
@@ -301,8 +304,10 @@ ENTRY(ia32_cstar_target) 
	/* no need to do an access_ok check here because r8 has been

	   32bit zero extended */ 

	/* hardware stack frame is complete now */	

	ASM_STAC

1:	movl	(%r8),%r9d

	_ASM_EXTABLE(1b,ia32_badarg)

	ASM_CLAC

	orl     $TS_COMPAT,TI_status+THREAD_INFO(%rsp,RIP-ARGOFFSET)

	testl   $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET)

	CFI_REMEMBER_STATE
@@ -365,6 +370,7 @@ cstar_tracesys: 
END(ia32_cstar_target)

				

ia32_badarg:

	ASM_CLAC

	movq $-EFAULT,%rax

	jmp ia32_sysret

	CFI_ENDPROC

arch/x86/include/asm/alternative-asm.h

+7 −2
Original line number Diff line number Diff line 
#ifndef _ASM_X86_ALTERNATIVE_ASM_H

#define _ASM_X86_ALTERNATIVE_ASM_H



#ifdef __ASSEMBLY__



#include <asm/asm.h>
@@ -5,10 +8,10 @@ 
#ifdef CONFIG_SMP

	.macro LOCK_PREFIX

672:	lock

	.section .smp_locks,"a"

	.pushsection .smp_locks,"a"

	.balign 4

	.long 672b - .

	.previous

	.popsection

	.endm

#else

	.macro LOCK_PREFIX
@@ -24,3 +27,5 @@ 
.endm



#endif  /*  __ASSEMBLY__  */



#endif /* _ASM_X86_ALTERNATIVE_ASM_H */