From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
linux-mm@kvack.org, linux-arch@vger.kernel.org,
linux-api@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Andy Lutomirski <luto@kernel.org>,
Balbir Singh <bsingharora@gmail.com>,
Borislav Petkov <bp@alien8.de>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Eugene Syromiatnikov <esyr@redhat.com>,
Florian Weimer <fweimer@redhat.com>,
"H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
Jonathan Corbet <corbet@lwn.net>,
Kees Cook <keescook@chromium.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Nadav Amit <nadav.amit@gmail.com>,
Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
Peter Zijlstra <peterz@infradead.org>,
Randy Dunlap <rdunlap@infradead.org>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
Dave Martin <Dave.Martin@arm.com>,
Weijiang Yang <weijiang.yang@intel.com>,
Pengfei Xu <pengfei.xu@intel.com>,
Haitao Huang <haitao.huang@intel.com>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [PATCH v27 26/31] x86/cet/shstk: Handle signals for shadow stack
Date: Fri, 21 May 2021 15:12:06 -0700 [thread overview]
Message-ID: <20210521221211.29077-27-yu-cheng.yu@intel.com> (raw)
In-Reply-To: <20210521221211.29077-1-yu-cheng.yu@intel.com>
A signal handler (if not changing ucontext) returns to the restorer, and
the restorer calls sigreturn. Thus, when setting up a signal frame, the
kernel:
- installs a shadow stack restore token pointing to the current shadow
stack address, and
- installs the restorer address below the restore token.
In sigreturn, the restore token is verified and shadow stack pointer is
restored.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
---
v27:
- Eliminate saving shadow stack pointer to signal context.
v25:
- Update commit log/comments for the sc_ext struct.
- Use restorer address already calculated.
- Change CONFIG_X86_CET to CONFIG_X86_SHADOW_STACK.
- Change X86_FEATURE_CET to X86_FEATURE_SHSTK.
- Eliminate writing to MSR_IA32_U_CET for shadow stack.
- Change wrmsrl() to wrmsrl_safe() and handle error.
arch/x86/ia32/ia32_signal.c | 25 +++++++++++++++++-----
arch/x86/include/asm/cet.h | 4 ++++
arch/x86/kernel/shstk.c | 42 +++++++++++++++++++++++++++++++++++++
arch/x86/kernel/signal.c | 13 ++++++++++++
4 files changed, 79 insertions(+), 5 deletions(-)
diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index 5e3d9b7fd5fb..d7a30bc98e66 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -35,6 +35,7 @@
#include <asm/sigframe.h>
#include <asm/sighandling.h>
#include <asm/smap.h>
+#include <asm/cet.h>
static inline void reload_segments(struct sigcontext_32 *sc)
{
@@ -113,6 +114,10 @@ COMPAT_SYSCALL_DEFINE0(sigreturn)
if (ia32_restore_sigcontext(regs, &frame->sc))
goto badframe;
+
+ if (restore_signal_shadow_stack())
+ goto badframe;
+
return regs->ax;
badframe:
@@ -138,6 +143,9 @@ COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))
goto badframe;
+ if (restore_signal_shadow_stack())
+ goto badframe;
+
if (compat_restore_altstack(&frame->uc.uc_stack))
goto badframe;
@@ -262,6 +270,9 @@ int ia32_setup_frame(int sig, struct ksignal *ksig,
restorer = &frame->retcode;
}
+ if (setup_signal_shadow_stack(1, restorer))
+ return -EFAULT;
+
if (!user_access_begin(frame, sizeof(*frame)))
return -EFAULT;
@@ -319,6 +330,15 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
+ if (ksig->ka.sa.sa_flags & SA_RESTORER)
+ restorer = ksig->ka.sa.sa_restorer;
+ else
+ restorer = current->mm->context.vdso +
+ vdso_image_32.sym___kernel_rt_sigreturn;
+
+ if (setup_signal_shadow_stack(1, restorer))
+ return -EFAULT;
+
if (!user_access_begin(frame, sizeof(*frame)))
return -EFAULT;
@@ -334,11 +354,6 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
unsafe_put_user(0, &frame->uc.uc_link, Efault);
unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
- if (ksig->ka.sa.sa_flags & SA_RESTORER)
- restorer = ksig->ka.sa.sa_restorer;
- else
- restorer = current->mm->context.vdso +
- vdso_image_32.sym___kernel_rt_sigreturn;
unsafe_put_user(ptr_to_compat(restorer), &frame->pretcode, Efault);
/*
diff --git a/arch/x86/include/asm/cet.h b/arch/x86/include/asm/cet.h
index aa533700ba31..2f7940d68ce3 100644
--- a/arch/x86/include/asm/cet.h
+++ b/arch/x86/include/asm/cet.h
@@ -24,6 +24,8 @@ void shstk_disable(void);
int shstk_setup_rstor_token(bool ia32, unsigned long restorer,
unsigned long *new_ssp);
int shstk_check_rstor_token(bool ia32, unsigned long *new_ssp);
+int setup_signal_shadow_stack(int ia32, void __user *restorer);
+int restore_signal_shadow_stack(void);
#else
static inline int shstk_setup(void) { return 0; }
static inline int shstk_alloc_thread_stack(struct task_struct *p,
@@ -35,6 +37,8 @@ static inline int shstk_setup_rstor_token(bool ia32, unsigned long restorer,
unsigned long *new_ssp) { return 0; }
static inline int shstk_check_rstor_token(bool ia32,
unsigned long *new_ssp) { return 0; }
+static inline int setup_signal_shadow_stack(int ia32, void __user *restorer) { return 0; }
+static inline int restore_signal_shadow_stack(void) { return 0; }
#endif
#endif /* __ASSEMBLY__ */
diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c
index 61ec300c1a97..5ef5e99afd75 100644
--- a/arch/x86/kernel/shstk.c
+++ b/arch/x86/kernel/shstk.c
@@ -314,3 +314,45 @@ int shstk_check_rstor_token(bool proc32, unsigned long *new_ssp)
return 0;
}
+
+int setup_signal_shadow_stack(int ia32, void __user *restorer)
+{
+ struct thread_shstk *shstk = ¤t->thread.shstk;
+ unsigned long new_ssp;
+ int err;
+
+ if (!cpu_feature_enabled(X86_FEATURE_SHSTK) || !shstk->size)
+ return 0;
+
+ err = shstk_setup_rstor_token(ia32, (unsigned long)restorer,
+ &new_ssp);
+ if (err)
+ return err;
+
+ start_update_msrs();
+ err = wrmsrl_safe(MSR_IA32_PL3_SSP, new_ssp);
+ end_update_msrs();
+
+ return err;
+}
+
+int restore_signal_shadow_stack(void)
+{
+ struct thread_shstk *shstk = ¤t->thread.shstk;
+ int ia32 = in_ia32_syscall();
+ unsigned long new_ssp;
+ int err;
+
+ if (!cpu_feature_enabled(X86_FEATURE_SHSTK) || !shstk->size)
+ return 0;
+
+ err = shstk_check_rstor_token(ia32, &new_ssp);
+ if (err)
+ return err;
+
+ start_update_msrs();
+ err = wrmsrl_safe(MSR_IA32_PL3_SSP, new_ssp);
+ end_update_msrs();
+
+ return err;
+}
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index a06cb107c0e8..4d42debbb5ef 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -46,6 +46,7 @@
#include <asm/syscall.h>
#include <asm/sigframe.h>
#include <asm/signal.h>
+#include <asm/cet.h>
#ifdef CONFIG_X86_64
/*
@@ -450,6 +451,9 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig,
frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
uc_flags = frame_uc_flags(regs);
+ if (setup_signal_shadow_stack(0, ksig->ka.sa.sa_restorer))
+ return -EFAULT;
+
if (!user_access_begin(frame, sizeof(*frame)))
return -EFAULT;
@@ -555,6 +559,9 @@ static int x32_setup_rt_frame(struct ksignal *ksig,
uc_flags = frame_uc_flags(regs);
+ if (setup_signal_shadow_stack(0, ksig->ka.sa.sa_restorer))
+ return -EFAULT;
+
if (!user_access_begin(frame, sizeof(*frame)))
return -EFAULT;
@@ -653,6 +660,9 @@ SYSCALL_DEFINE0(rt_sigreturn)
if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
goto badframe;
+ if (restore_signal_shadow_stack())
+ goto badframe;
+
if (restore_altstack(&frame->uc.uc_stack))
goto badframe;
@@ -856,6 +866,9 @@ COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn)
if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
goto badframe;
+ if (restore_signal_shadow_stack())
+ goto badframe;
+
if (compat_restore_altstack(&frame->uc.uc_stack))
goto badframe;
--
2.21.0
next prev parent reply other threads:[~2021-05-21 22:13 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-21 22:11 [PATCH v27 00/31] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 01/31] Documentation/x86: Add CET description Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 02/31] x86/cet/shstk: Add Kconfig option for Shadow Stack Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 03/31] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 04/31] x86/cpufeatures: Introduce CPU setup and option parsing for CET Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 05/31] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 06/31] x86/cet: Add control-protection fault handler Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 07/31] x86/mm: Remove _PAGE_DIRTY from kernel RO pages Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 08/31] x86/mm: Move pmd_write(), pud_write() up in the file Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 09/31] x86/mm: Introduce _PAGE_COW Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 10/31] drm/i915/gvt: Change _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 11/31] x86/mm: Update pte_modify for _PAGE_COW Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 12/31] x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for transition from _PAGE_DIRTY to _PAGE_COW Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 13/31] mm: Move VM_UFFD_MINOR_BIT from 37 to 38 Yu-cheng Yu
2021-05-21 22:25 ` Axel Rasmussen
2021-05-22 1:58 ` Yu, Yu-cheng
2021-05-21 22:11 ` [PATCH v27 14/31] mm: Introduce VM_SHADOW_STACK for shadow stack memory Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 15/31] x86/mm: Shadow Stack page fault error checking Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 16/31] x86/mm: Update maybe_mkwrite() for shadow stack Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 17/31] mm: Fixup places that call pte_mkwrite() directly Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 18/31] mm: Add guard pages around a shadow stack Yu-cheng Yu
2021-05-21 22:11 ` [PATCH v27 19/31] mm/mmap: Add shadow stack pages to memory accounting Yu-cheng Yu
2021-05-21 22:12 ` [PATCH v27 20/31] mm: Update can_follow_write_pte() for shadow stack Yu-cheng Yu
2021-05-21 22:12 ` [PATCH v27 21/31] mm/mprotect: Exclude shadow stack from preserve_write Yu-cheng Yu
2021-05-21 22:12 ` [PATCH v27 22/31] mm: Re-introduce vm_flags to do_mmap() Yu-cheng Yu
2021-05-21 22:12 ` [PATCH v27 23/31] x86/cet/shstk: Add user-mode shadow stack support Yu-cheng Yu
2021-07-19 18:23 ` Edgecombe, Rick P
2021-07-20 17:13 ` Yu, Yu-cheng
2021-05-21 22:12 ` [PATCH v27 24/31] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2021-05-22 23:39 ` Andy Lutomirski
2021-05-25 15:04 ` Yu, Yu-cheng
2021-07-21 18:14 ` John Allen
2021-07-21 18:28 ` Florian Weimer
2021-07-21 18:34 ` Yu, Yu-cheng
2021-07-28 21:34 ` John Allen
2021-07-21 18:37 ` Dave Hansen
2021-07-21 20:14 ` H.J. Lu
2021-05-21 22:12 ` [PATCH v27 25/31] x86/cet/shstk: Introduce shadow stack token setup/verify routines Yu-cheng Yu
2021-05-21 22:12 ` Yu-cheng Yu [this message]
2021-05-21 22:12 ` [PATCH v27 27/31] ELF: Introduce arch_setup_elf_property() Yu-cheng Yu
2021-05-25 10:54 ` Catalin Marinas
2021-05-21 22:12 ` [PATCH v27 28/31] x86/cet/shstk: Add arch_prctl functions for shadow stack Yu-cheng Yu
2021-05-21 22:12 ` [PATCH v27 29/31] mm: Move arch_calc_vm_prot_bits() to arch/x86/include/asm/mman.h Yu-cheng Yu
2021-05-21 22:12 ` [PATCH v27 30/31] mm: Update arch_validate_flags() to test vma anonymous Yu-cheng Yu
2021-05-25 11:00 ` Catalin Marinas
2021-05-25 15:03 ` Yu, Yu-cheng
2021-05-21 22:12 ` [PATCH v27 31/31] mm: Introduce PROT_SHADOW_STACK for shadow stack Yu-cheng Yu
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