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>,
Dave Martin <Dave.Martin@arm.com>,
Weijiang Yang <weijiang.yang@intel.com>,
Pengfei Xu <pengfei.xu@intel.com>,
Haitao Huang <haitao.huang@intel.com>,
Rick P Edgecombe <rick.p.edgecombe@intel.com>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>,
Michael Kerrisk <mtk.manpages@gmail.com>
Subject: [PATCH v29 06/32] x86/cet: Add control-protection fault handler
Date: Fri, 20 Aug 2021 11:11:35 -0700 [thread overview]
Message-ID: <20210820181201.31490-7-yu-cheng.yu@intel.com> (raw)
In-Reply-To: <20210820181201.31490-1-yu-cheng.yu@intel.com>
A control-protection fault is triggered when a control-flow transfer
attempt violates Shadow Stack or Indirect Branch Tracking constraints.
For example, the return address for a RET instruction differs from the copy
on the shadow stack; or an indirect JMP instruction, without the NOTRACK
prefix, arrives at a non-ENDBR opcode.
The control-protection fault handler works in a similar way as the general
protection fault handler. It provides the si_code SEGV_CPERR to the signal
handler.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
---
v29:
- Remove pr_emerg() since it is followed by die().
- Change boot_cpu_has() to cpu_feature_enabled().
v25:
- Change CONFIG_X86_CET to CONFIG_X86_SHADOW_STACK.
- Change X86_FEATURE_CET to X86_FEATURE_SHSTK.
---
arch/x86/include/asm/idtentry.h | 4 ++
arch/x86/kernel/idt.c | 4 ++
arch/x86/kernel/signal_compat.c | 2 +-
arch/x86/kernel/traps.c | 62 ++++++++++++++++++++++++++++++
include/uapi/asm-generic/siginfo.h | 3 +-
5 files changed, 73 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index 1345088e9902..a90791433152 100644
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -562,6 +562,10 @@ DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_SS, exc_stack_segment);
DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_GP, exc_general_protection);
DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_AC, exc_alignment_check);
+#ifdef CONFIG_X86_SHADOW_STACK
+DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_CP, exc_control_protection);
+#endif
+
/* Raw exception entries which need extra work */
DECLARE_IDTENTRY_RAW(X86_TRAP_UD, exc_invalid_op);
DECLARE_IDTENTRY_RAW(X86_TRAP_BP, exc_int3);
diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
index df0fa695bb09..9f1bdaabc246 100644
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c
@@ -113,6 +113,10 @@ static const __initconst struct idt_data def_idts[] = {
#elif defined(CONFIG_X86_32)
SYSG(IA32_SYSCALL_VECTOR, entry_INT80_32),
#endif
+
+#ifdef CONFIG_X86_SHADOW_STACK
+ INTG(X86_TRAP_CP, asm_exc_control_protection),
+#endif
};
/*
diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
index 06743ec054d2..049ea3dcc6cb 100644
--- a/arch/x86/kernel/signal_compat.c
+++ b/arch/x86/kernel/signal_compat.c
@@ -27,7 +27,7 @@ static inline void signal_compat_build_tests(void)
*/
BUILD_BUG_ON(NSIGILL != 11);
BUILD_BUG_ON(NSIGFPE != 15);
- BUILD_BUG_ON(NSIGSEGV != 9);
+ BUILD_BUG_ON(NSIGSEGV != 10);
BUILD_BUG_ON(NSIGBUS != 5);
BUILD_BUG_ON(NSIGTRAP != 6);
BUILD_BUG_ON(NSIGCHLD != 6);
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index a58800973aed..b64192314a6d 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -39,6 +39,7 @@
#include <linux/io.h>
#include <linux/hardirq.h>
#include <linux/atomic.h>
+#include <linux/nospec.h>
#include <asm/stacktrace.h>
#include <asm/processor.h>
@@ -607,6 +608,67 @@ DEFINE_IDTENTRY_ERRORCODE(exc_general_protection)
cond_local_irq_disable(regs);
}
+#ifdef CONFIG_X86_SHADOW_STACK
+static const char * const control_protection_err[] = {
+ "unknown",
+ "near-ret",
+ "far-ret/iret",
+ "endbranch",
+ "rstorssp",
+ "setssbsy",
+ "unknown",
+};
+
+static DEFINE_RATELIMIT_STATE(cpf_rate, DEFAULT_RATELIMIT_INTERVAL,
+ DEFAULT_RATELIMIT_BURST);
+
+/*
+ * When a control protection exception occurs, send a signal to the responsible
+ * application. Currently, control protection is only enabled for user mode.
+ * This exception should not come from kernel mode.
+ */
+DEFINE_IDTENTRY_ERRORCODE(exc_control_protection)
+{
+ struct task_struct *tsk;
+
+ if (!user_mode(regs)) {
+ die("kernel control protection fault", regs, error_code);
+ panic("Unexpected kernel control protection fault. Machine halted.");
+ }
+
+ cond_local_irq_enable(regs);
+
+ if (!cpu_feature_enabled(X86_FEATURE_SHSTK))
+ WARN_ONCE(1, "Control protection fault with CET support disabled\n");
+
+ tsk = current;
+ tsk->thread.error_code = error_code;
+ tsk->thread.trap_nr = X86_TRAP_CP;
+
+ /*
+ * Ratelimit to prevent log spamming.
+ */
+ if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
+ __ratelimit(&cpf_rate)) {
+ unsigned long ssp;
+ int cpf_type;
+
+ cpf_type = array_index_nospec(error_code, ARRAY_SIZE(control_protection_err));
+
+ rdmsrl(MSR_IA32_PL3_SSP, ssp);
+ pr_emerg("%s[%d] control protection ip:%lx sp:%lx ssp:%lx error:%lx(%s)",
+ tsk->comm, task_pid_nr(tsk),
+ regs->ip, regs->sp, ssp, error_code,
+ control_protection_err[cpf_type]);
+ print_vma_addr(KERN_CONT " in ", regs->ip);
+ pr_cont("\n");
+ }
+
+ force_sig_fault(SIGSEGV, SEGV_CPERR, (void __user *)0);
+ cond_local_irq_disable(regs);
+}
+#endif
+
static bool do_int3(struct pt_regs *regs)
{
int res;
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 5a3c221f4c9d..a1a153ea3cc3 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -235,7 +235,8 @@ typedef struct siginfo {
#define SEGV_ADIPERR 7 /* Precise MCD exception */
#define SEGV_MTEAERR 8 /* Asynchronous ARM MTE error */
#define SEGV_MTESERR 9 /* Synchronous ARM MTE exception */
-#define NSIGSEGV 9
+#define SEGV_CPERR 10 /* Control protection fault */
+#define NSIGSEGV 10
/*
* SIGBUS si_codes
--
2.21.0
next prev parent reply other threads:[~2021-08-20 18:18 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-20 18:11 [PATCH v29 00/32] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 01/32] Documentation/x86: Add CET description Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 02/32] x86/cet/shstk: Add Kconfig option for Shadow Stack Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 03/32] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 04/32] x86/cpufeatures: Introduce CPU setup and option parsing for CET Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 05/32] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states Yu-cheng Yu
2021-08-20 18:11 ` Yu-cheng Yu [this message]
2021-08-20 18:11 ` [PATCH v29 07/32] x86/mm: Remove _PAGE_DIRTY from kernel RO pages Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 08/32] x86/mm: Move pmd_write(), pud_write() up in the file Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 09/32] x86/mm: Introduce _PAGE_COW Yu-cheng Yu
2021-08-21 19:20 ` Edgecombe, Rick P
2021-08-22 2:59 ` Edgecombe, Rick P
2021-08-20 18:11 ` [PATCH v29 10/32] drm/i915/gvt: Change _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 11/32] x86/mm: Update pte_modify for _PAGE_COW Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 12/32] x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for transition from _PAGE_DIRTY to _PAGE_COW Yu-cheng Yu
2021-08-26 10:42 ` Borislav Petkov
2021-08-20 18:11 ` [PATCH v29 13/32] mm: Move VM_UFFD_MINOR_BIT from 37 to 38 Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 14/32] mm: Introduce VM_SHADOW_STACK for shadow stack memory Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 15/32] x86/mm: Shadow Stack page fault error checking Yu-cheng Yu
2021-08-26 10:55 ` Borislav Petkov
2021-08-20 18:11 ` [PATCH v29 16/32] x86/mm: Update maybe_mkwrite() for shadow stack Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 17/32] mm: Fixup places that call pte_mkwrite() directly Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 18/32] mm: Add guard pages around a shadow stack Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 19/32] mm/mmap: Add shadow stack pages to memory accounting Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 20/32] mm: Update can_follow_write_pte() for shadow stack Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 21/32] mm/mprotect: Exclude shadow stack from preserve_write Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 22/32] mm: Re-introduce vm_flags to do_mmap() Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 23/32] x86/cet/shstk: Add user-mode shadow stack support Yu-cheng Yu
2021-08-26 16:25 ` Borislav Petkov
2021-08-27 18:10 ` Yu, Yu-cheng
2021-08-27 18:21 ` Borislav Petkov
2021-08-27 18:37 ` Yu, Yu-cheng
2021-08-27 18:46 ` Borislav Petkov
2021-08-27 20:25 ` Dave Hansen
2021-09-01 13:00 ` Borislav Petkov
2021-09-01 15:24 ` Dave Hansen
2021-08-20 18:11 ` [PATCH v29 24/32] x86/process: Change copy_thread() argument 'arg' to 'stack_size' Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 25/32] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2021-08-26 16:50 ` Borislav Petkov
2021-08-26 17:22 ` H.J. Lu
2021-08-26 17:28 ` Borislav Petkov
2021-08-26 17:33 ` Yu, Yu-cheng
2021-08-26 17:25 ` Yu, Yu-cheng
2021-08-20 18:11 ` [PATCH v29 26/32] x86/cet/shstk: Introduce shadow stack token setup/verify routines Yu-cheng Yu
2021-08-26 17:21 ` Borislav Petkov
2021-08-20 18:11 ` [PATCH v29 27/32] x86/cet/shstk: Handle signals for shadow stack Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 28/32] ELF: Introduce arch_setup_elf_property() Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 29/32] x86/cet/shstk: Add arch_prctl functions for shadow stack Yu-cheng Yu
2021-08-20 18:11 ` [PATCH v29 30/32] mm: Move arch_calc_vm_prot_bits() to arch/x86/include/asm/mman.h Yu-cheng Yu
2021-08-20 18:12 ` [PATCH v29 31/32] mm: Update arch_validate_flags() to test vma anonymous Yu-cheng Yu
2021-08-20 18:12 ` [PATCH v29 32/32] mm: Introduce PROT_SHADOW_STACK for shadow stack Yu-cheng Yu
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