mirrors
/
linux-stable
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Releases Wiki Activity

x86: Introduce userspace API for shadow stack 

Add three new arch_prctl() handles:

 - ARCH_SHSTK_ENABLE/DISABLE enables or disables the specified
   feature. Returns 0 on success or a negative value on error.

 - ARCH_SHSTK_LOCK prevents future disabling or enabling of the
   specified feature. Returns 0 on success or a negative value
   on error.

The features are handled per-thread and inherited over fork(2)/clone(2),
but reset on exec().

Co-developed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Tested-by: Pengfei Xu <pengfei.xu@intel.com>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/all/20230613001108.3040476-27-rick.p.edgecombe%40intel.com
This commit is contained in:
Rick Edgecombe 2023-06-12 17:10:52 -07:00 committed by Dave Hansen
parent 6ee836687a
commit 98cfa46309
6 changed files with 85 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/x86/include/asm/processor.h
View File

@ -28,6 +28,7 @@ struct vm86;
#include <asm/unwind_hints.h>
#include <asm/vmxfeatures.h>
#include <asm/vdso/processor.h>
#include <asm/shstk.h>
#include <linux/personality.h>
#include <linux/cache.h>
@ -475,6 +476,11 @@ struct thread_struct {
*/
u32 pkru;
#ifdef CONFIG_X86_USER_SHADOW_STACK
unsigned long features;
unsigned long features_locked;
#endif
/* Floating point and extended processor state */
struct fpu fpu;
/*

21
arch/x86/include/asm/shstk.h Normal file
View File

@ -0,0 +1,21 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_SHSTK_H
#define _ASM_X86_SHSTK_H
#ifndef __ASSEMBLY__
#include <linux/types.h>
struct task_struct;
#ifdef CONFIG_X86_USER_SHADOW_STACK
long shstk_prctl(struct task_struct *task, int option, unsigned long features);
void reset_thread_features(void);
#else
static inline long shstk_prctl(struct task_struct *task, int option,
unsigned long arg2) { return -EINVAL; }
static inline void reset_thread_features(void) {}
#endif /* CONFIG_X86_USER_SHADOW_STACK */
#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_SHSTK_H */

6
arch/x86/include/uapi/asm/prctl.h
View File

@ -23,9 +23,15 @@
#define ARCH_MAP_VDSO_32 0x2002
#define ARCH_MAP_VDSO_64 0x2003
/* Don't use 0x3001-0x3004 because of old glibcs */
#define ARCH_GET_UNTAG_MASK 0x4001
#define ARCH_ENABLE_TAGGED_ADDR 0x4002
#define ARCH_GET_MAX_TAG_BITS 0x4003
#define ARCH_FORCE_TAGGED_SVA 0x4004
#define ARCH_SHSTK_ENABLE 0x5001
#define ARCH_SHSTK_DISABLE 0x5002
#define ARCH_SHSTK_LOCK 0x5003
#endif /* _ASM_X86_PRCTL_H */

2
arch/x86/kernel/Makefile
View File

@ -147,6 +147,8 @@ obj-$(CONFIG_CALL_THUNKS) += callthunks.o
obj-$(CONFIG_X86_CET) += cet.o
obj-$(CONFIG_X86_USER_SHADOW_STACK) += shstk.o
###
# 64 bit specific files
ifeq ($(CONFIG_X86_64),y)

6
arch/x86/kernel/process_64.c
View File

@ -515,6 +515,8 @@ start_thread_common(struct pt_regs *regs, unsigned long new_ip,
load_gs_index(__USER_DS);
}
reset_thread_features();
loadsegment(fs, 0);
loadsegment(es, _ds);
loadsegment(ds, _ds);
@ -894,6 +896,10 @@ long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2)
else
return put_user(LAM_U57_BITS, (unsigned long __user *)arg2);
#endif
case ARCH_SHSTK_ENABLE:
case ARCH_SHSTK_DISABLE:
case ARCH_SHSTK_LOCK:
return shstk_prctl(task, option, arg2);
default:
ret = -EINVAL;
break;

44
arch/x86/kernel/shstk.c Normal file
View File

@ -0,0 +1,44 @@
// SPDX-License-Identifier: GPL-2.0
/*
* shstk.c - Intel shadow stack support
*
* Copyright (c) 2021, Intel Corporation.
* Yu-cheng Yu <yu-cheng.yu@intel.com>
*/
#include <linux/sched.h>
#include <linux/bitops.h>
#include <asm/prctl.h>
void reset_thread_features(void)
{
current->thread.features = 0;
current->thread.features_locked = 0;
}
long shstk_prctl(struct task_struct *task, int option, unsigned long features)
{
if (option == ARCH_SHSTK_LOCK) {
task->thread.features_locked |= features;
return 0;
}
/* Don't allow via ptrace */
if (task != current)
return -EINVAL;
/* Do not allow to change locked features */
if (features & task->thread.features_locked)
return -EPERM;
/* Only support enabling/disabling one feature at a time. */
if (hweight_long(features) > 1)
return -EINVAL;
if (option == ARCH_SHSTK_DISABLE) {
return -EINVAL;
}
/* Handle ARCH_SHSTK_ENABLE */
return -EINVAL;
}