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

Browse Source 
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
This commit is contained in:
Linus Torvalds
2012-10-01 13:59:17 -07:00
parent a57d985e37 b2cc2a074d
commit 15385dfe7e
31 changed files with 410 additions and 116 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
arch/x86/kernel/acpi/sleep.c
View File

@@ -43,17 +43,22 @@ int acpi_suspend_lowlevel(void)
header->video_mode = saved_video_mode;
header->pmode_behavior = 0;
#ifndef CONFIG_64BIT
store_gdt((struct desc_ptr *)&header->pmode_gdt);
if (rdmsr_safe(MSR_EFER, &header->pmode_efer_low,
&header->pmode_efer_high))
header->pmode_efer_low = header->pmode_efer_high = 0;
if (!rdmsr_safe(MSR_EFER,
&header->pmode_efer_low,
&header->pmode_efer_high))
header->pmode_behavior |= (1 << WAKEUP_BEHAVIOR_RESTORE_EFER);
#endif /* !CONFIG_64BIT */
header->pmode_cr0 = read_cr0();
header->pmode_cr4 = read_cr4_safe();
header->pmode_behavior = 0;
if (__this_cpu_read(cpu_info.cpuid_level) >= 0) {
header->pmode_cr4 = read_cr4();
header->pmode_behavior |= (1 << WAKEUP_BEHAVIOR_RESTORE_CR4);
}
if (!rdmsr_safe(MSR_IA32_MISC_ENABLE,
&header->pmode_misc_en_low,
&header->pmode_misc_en_high))

44
arch/x86/kernel/cpu/common.c
View File

@@ -259,23 +259,36 @@ static inline void squash_the_stupid_serial_number(struct cpuinfo_x86 *c)
}
#endif
static int disable_smep __cpuinitdata;
static __init int setup_disable_smep(char *arg)
{
disable_smep = 1;
setup_clear_cpu_cap(X86_FEATURE_SMEP);
return 1;
}
__setup("nosmep", setup_disable_smep);
static __cpuinit void setup_smep(struct cpuinfo_x86 *c)
static __always_inline void setup_smep(struct cpuinfo_x86 *c)
{
if (cpu_has(c, X86_FEATURE_SMEP)) {
if (unlikely(disable_smep)) {
setup_clear_cpu_cap(X86_FEATURE_SMEP);
clear_in_cr4(X86_CR4_SMEP);
} else
set_in_cr4(X86_CR4_SMEP);
}
if (cpu_has(c, X86_FEATURE_SMEP))
set_in_cr4(X86_CR4_SMEP);
}
static __init int setup_disable_smap(char *arg)
{
setup_clear_cpu_cap(X86_FEATURE_SMAP);
return 1;
}
__setup("nosmap", setup_disable_smap);
static __always_inline void setup_smap(struct cpuinfo_x86 *c)
{
unsigned long eflags;
/* This should have been cleared long ago */
raw_local_save_flags(eflags);
BUG_ON(eflags & X86_EFLAGS_AC);
if (cpu_has(c, X86_FEATURE_SMAP))
set_in_cr4(X86_CR4_SMAP);
}
/*
@@ -712,8 +725,6 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
c->cpu_index = 0;
filter_cpuid_features(c, false);
setup_smep(c);
if (this_cpu->c_bsp_init)
this_cpu->c_bsp_init(c);
}
@@ -798,8 +809,6 @@ static void __cpuinit generic_identify(struct cpuinfo_x86 *c)
c->phys_proc_id = c->initial_apicid;
}
setup_smep(c);
get_model_name(c); /* Default name */
detect_nopl(c);
@@ -864,6 +873,10 @@ static void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
/* Disable the PN if appropriate */
squash_the_stupid_serial_number(c);
/* Set up SMEP/SMAP */
setup_smep(c);
setup_smap(c);
/*
* The vendor-specific functions might have changed features.
* Now we do "generic changes."
@@ -1114,7 +1127,8 @@ void syscall_init(void)
/* Flags to clear on syscall */
wrmsrl(MSR_SYSCALL_MASK,
X86_EFLAGS_TF|X86_EFLAGS_DF|X86_EFLAGS_IF|X86_EFLAGS_IOPL);
X86_EFLAGS_TF|X86_EFLAGS_DF|X86_EFLAGS_IF|
X86_EFLAGS_IOPL|X86_EFLAGS_AC);
}
/*

26
arch/x86/kernel/entry_32.S
View File

@@ -57,6 +57,7 @@
#include <asm/cpufeature.h>
#include <asm/alternative-asm.h>
#include <asm/asm.h>
#include <asm/smap.h>
/* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */
#include <linux/elf-em.h>
@@ -407,7 +408,9 @@ sysenter_past_esp:
*/
cmpl $__PAGE_OFFSET-3,%ebp
jae syscall_fault
ASM_STAC
1: movl (%ebp),%ebp
ASM_CLAC
movl %ebp,PT_EBP(%esp)
_ASM_EXTABLE(1b,syscall_fault)
@@ -488,6 +491,7 @@ ENDPROC(ia32_sysenter_target)
# system call handler stub
ENTRY(system_call)
RING0_INT_FRAME # can't unwind into user space anyway
ASM_CLAC
pushl_cfi %eax # save orig_eax
SAVE_ALL
GET_THREAD_INFO(%ebp)
@@ -670,6 +674,7 @@ END(syscall_exit_work)
RING0_INT_FRAME # can't unwind into user space anyway
syscall_fault:
ASM_CLAC
GET_THREAD_INFO(%ebp)
movl $-EFAULT,PT_EAX(%esp)
jmp resume_userspace
@@ -825,6 +830,7 @@ END(interrupt)
*/
.p2align CONFIG_X86_L1_CACHE_SHIFT
common_interrupt:
ASM_CLAC
addl $-0x80,(%esp) /* Adjust vector into the [-256,-1] range */
SAVE_ALL
TRACE_IRQS_OFF
@@ -841,6 +847,7 @@ ENDPROC(common_interrupt)
#define BUILD_INTERRUPT3(name, nr, fn) \
ENTRY(name) \
RING0_INT_FRAME; \
ASM_CLAC; \
pushl_cfi $~(nr); \
SAVE_ALL; \
TRACE_IRQS_OFF \
@@ -857,6 +864,7 @@ ENDPROC(name)
ENTRY(coprocessor_error)
RING0_INT_FRAME
ASM_CLAC
pushl_cfi $0
pushl_cfi $do_coprocessor_error
jmp error_code
@@ -865,6 +873,7 @@ END(coprocessor_error)
ENTRY(simd_coprocessor_error)
RING0_INT_FRAME
ASM_CLAC
pushl_cfi $0
#ifdef CONFIG_X86_INVD_BUG
/* AMD 486 bug: invd from userspace calls exception 19 instead of #GP */
@@ -886,6 +895,7 @@ END(simd_coprocessor_error)
ENTRY(device_not_available)
RING0_INT_FRAME
ASM_CLAC
pushl_cfi $-1 # mark this as an int
pushl_cfi $do_device_not_available
jmp error_code
@@ -906,6 +916,7 @@ END(native_irq_enable_sysexit)
ENTRY(overflow)
RING0_INT_FRAME
ASM_CLAC
pushl_cfi $0
pushl_cfi $do_overflow
jmp error_code
@@ -914,6 +925,7 @@ END(overflow)
ENTRY(bounds)
RING0_INT_FRAME
ASM_CLAC
pushl_cfi $0
pushl_cfi $do_bounds
jmp error_code
@@ -922,6 +934,7 @@ END(bounds)
ENTRY(invalid_op)
RING0_INT_FRAME
ASM_CLAC
pushl_cfi $0
pushl_cfi $do_invalid_op
jmp error_code
@@ -930,6 +943,7 @@ END(invalid_op)
ENTRY(coprocessor_segment_overrun)
RING0_INT_FRAME
ASM_CLAC
pushl_cfi $0
pushl_cfi $do_coprocessor_segment_overrun
jmp error_code
@@ -938,6 +952,7 @@ END(coprocessor_segment_overrun)
ENTRY(invalid_TSS)
RING0_EC_FRAME
ASM_CLAC
pushl_cfi $do_invalid_TSS
jmp error_code
CFI_ENDPROC
@@ -945,6 +960,7 @@ END(invalid_TSS)
ENTRY(segment_not_present)
RING0_EC_FRAME
ASM_CLAC
pushl_cfi $do_segment_not_present
jmp error_code
CFI_ENDPROC
@@ -952,6 +968,7 @@ END(segment_not_present)
ENTRY(stack_segment)
RING0_EC_FRAME
ASM_CLAC
pushl_cfi $do_stack_segment
jmp error_code
CFI_ENDPROC
@@ -959,6 +976,7 @@ END(stack_segment)
ENTRY(alignment_check)
RING0_EC_FRAME
ASM_CLAC
pushl_cfi $do_alignment_check
jmp error_code
CFI_ENDPROC
@@ -966,6 +984,7 @@ END(alignment_check)
ENTRY(divide_error)
RING0_INT_FRAME
ASM_CLAC
pushl_cfi $0 # no error code
pushl_cfi $do_divide_error
jmp error_code
@@ -975,6 +994,7 @@ END(divide_error)
#ifdef CONFIG_X86_MCE
ENTRY(machine_check)
RING0_INT_FRAME
ASM_CLAC
pushl_cfi $0
pushl_cfi machine_check_vector
jmp error_code
@@ -984,6 +1004,7 @@ END(machine_check)
ENTRY(spurious_interrupt_bug)
RING0_INT_FRAME
ASM_CLAC
pushl_cfi $0
pushl_cfi $do_spurious_interrupt_bug
jmp error_code
@@ -1273,6 +1294,7 @@ return_to_handler:
ENTRY(page_fault)
RING0_EC_FRAME
ASM_CLAC
pushl_cfi $do_page_fault
ALIGN
error_code:
@@ -1345,6 +1367,7 @@ END(page_fault)
ENTRY(debug)
RING0_INT_FRAME
ASM_CLAC
cmpl $ia32_sysenter_target,(%esp)
jne debug_stack_correct
FIX_STACK 12, debug_stack_correct, debug_esp_fix_insn
@@ -1369,6 +1392,7 @@ END(debug)
*/
ENTRY(nmi)
RING0_INT_FRAME
ASM_CLAC
pushl_cfi %eax
movl %ss, %eax
cmpw $__ESPFIX_SS, %ax
@@ -1439,6 +1463,7 @@ END(nmi)
ENTRY(int3)
RING0_INT_FRAME
ASM_CLAC
pushl_cfi $-1 # mark this as an int
SAVE_ALL
TRACE_IRQS_OFF
@@ -1459,6 +1484,7 @@ END(general_protection)
#ifdef CONFIG_KVM_GUEST
ENTRY(async_page_fault)
RING0_EC_FRAME
ASM_CLAC
pushl_cfi $do_async_page_fault
jmp error_code
CFI_ENDPROC

11
arch/x86/kernel/entry_64.S
View File

@@ -57,6 +57,7 @@
#include <asm/percpu.h>
#include <asm/asm.h>
#include <asm/rcu.h>
#include <asm/smap.h>
#include <linux/err.h>
/* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */
@@ -568,7 +569,8 @@ END(ret_from_fork)
* System call entry. Up to 6 arguments in registers are supported.
*
* SYSCALL does not save anything on the stack and does not change the
* stack pointer.
* stack pointer. However, it does mask the flags register for us, so
* CLD and CLAC are not needed.
*/
/*
@@ -987,6 +989,7 @@ END(interrupt)
*/
.p2align CONFIG_X86_L1_CACHE_SHIFT
common_interrupt:
ASM_CLAC
XCPT_FRAME
addq $-0x80,(%rsp) /* Adjust vector to [-256,-1] range */
interrupt do_IRQ
@@ -1126,6 +1129,7 @@ END(common_interrupt)
*/
.macro apicinterrupt num sym do_sym
ENTRY(\sym)
ASM_CLAC
INTR_FRAME
pushq_cfi $~(\num)
.Lcommon_\sym:
@@ -1180,6 +1184,7 @@ apicinterrupt IRQ_WORK_VECTOR \
*/
.macro zeroentry sym do_sym
ENTRY(\sym)
ASM_CLAC
INTR_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
@@ -1197,6 +1202,7 @@ END(\sym)
.macro paranoidzeroentry sym do_sym
ENTRY(\sym)
ASM_CLAC
INTR_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
@@ -1215,6 +1221,7 @@ END(\sym)
#define INIT_TSS_IST(x) PER_CPU_VAR(init_tss) + (TSS_ist + ((x) - 1) * 8)
.macro paranoidzeroentry_ist sym do_sym ist
ENTRY(\sym)
ASM_CLAC
INTR_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
@@ -1234,6 +1241,7 @@ END(\sym)
.macro errorentry sym do_sym
ENTRY(\sym)
ASM_CLAC
XCPT_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
subq $ORIG_RAX-R15, %rsp
@@ -1252,6 +1260,7 @@ END(\sym)
/* error code is on the stack already */
.macro paranoiderrorentry sym do_sym
ENTRY(\sym)
ASM_CLAC
XCPT_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
subq $ORIG_RAX-R15, %rsp

31
arch/x86/kernel/head_32.S
View File

@@ -287,27 +287,28 @@ ENTRY(startup_32_smp)
leal -__PAGE_OFFSET(%ecx),%esp
default_entry:
/*
* New page tables may be in 4Mbyte page mode and may
* be using the global pages.
*
* NOTE! If we are on a 486 we may have no cr4 at all!
* So we do not try to touch it unless we really have
* some bits in it to set. This won't work if the BSP
* implements cr4 but this AP does not -- very unlikely
* but be warned! The same applies to the pse feature
* if not equally supported. --macro
*
* NOTE! We have to correct for the fact that we're
* not yet offset PAGE_OFFSET..
* Specifically, cr4 exists if and only if CPUID exists,
* which in turn exists if and only if EFLAGS.ID exists.
*/
#define cr4_bits pa(mmu_cr4_features)
movl cr4_bits,%edx
andl %edx,%edx
jz 6f
movl %cr4,%eax # Turn on paging options (PSE,PAE,..)
orl %edx,%eax
movl $X86_EFLAGS_ID,%ecx
pushl %ecx
popfl
pushfl
popl %eax
pushl $0
popfl
pushfl
popl %edx
xorl %edx,%eax
testl %ecx,%eax
jz 6f # No ID flag = no CPUID = no CR4
movl pa(mmu_cr4_features),%eax
movl %eax,%cr4
testb $X86_CR4_PAE, %al # check if PAE is enabled

24
arch/x86/kernel/signal.c
View File

@@ -114,11 +114,12 @@ int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
regs->orig_ax = -1; /* disable syscall checks */
get_user_ex(buf, &sc->fpstate);
err |= restore_xstate_sig(buf, config_enabled(CONFIG_X86_32));
get_user_ex(*pax, &sc->ax);
} get_user_catch(err);
err |= restore_xstate_sig(buf, config_enabled(CONFIG_X86_32));
return err;
}
@@ -355,7 +356,6 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
put_user_ex(sig, &frame->sig);
put_user_ex(&frame->info, &frame->pinfo);
put_user_ex(&frame->uc, &frame->puc);
err |= copy_siginfo_to_user(&frame->info, info);
/* Create the ucontext. */
if (cpu_has_xsave)
@@ -367,9 +367,6 @@ static int __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 |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
regs, set->sig[0]);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
/* Set up to return from userspace. */
restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
@@ -386,6 +383,11 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
*/
put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
} put_user_catch(err);
err |= copy_siginfo_to_user(&frame->info, info);
err |= 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;
@@ -434,8 +436,6 @@ static int __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(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
@@ -448,6 +448,9 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
}
} put_user_catch(err);
err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
if (err)
return -EFAULT;
@@ -504,9 +507,6 @@ static int x32_setup_rt_frame(int sig, struct k_sigaction *ka,
&frame->uc.uc_stack.ss_flags);
put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
put_user_ex(0, &frame->uc.uc__pad0);
err |= 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;
@@ -518,6 +518,10 @@ static int x32_setup_rt_frame(int sig, struct k_sigaction *ka,
put_user_ex(restorer, &frame->pretcode);
} put_user_catch(err);
err |= 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;

6
arch/x86/kernel/xsave.c
View File

@@ -315,7 +315,7 @@ static inline int restore_user_xstate(void __user *buf, u64 xbv, int fx_only)
if ((unsigned long)buf % 64 || fx_only) {
u64 init_bv = pcntxt_mask & ~XSTATE_FPSSE;
xrstor_state(init_xstate_buf, init_bv);
return fxrstor_checking((__force void *) buf);
return fxrstor_user(buf);
} else {
u64 init_bv = pcntxt_mask & ~xbv;
if (unlikely(init_bv))
@@ -323,9 +323,9 @@ static inline int restore_user_xstate(void __user *buf, u64 xbv, int fx_only)
return xrestore_user(buf, xbv);
}
} else if (use_fxsr()) {
return fxrstor_checking((__force void *) buf);
return fxrstor_user(buf);
} else
return frstor_checking((__force void *) buf);
return frstor_user(buf);
}
int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)