From: Alexandre Chartre <alexandre.chartre@oracle.com>
To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
hpa@zytor.com, x86@kernel.org, dave.hansen@linux.intel.com,
luto@kernel.org, peterz@infradead.org,
linux-kernel@vger.kernel.org, thomas.lendacky@amd.com,
jroedel@suse.de
Cc: konrad.wilk@oracle.com, jan.setjeeilers@oracle.com,
junaids@google.com, oweisse@google.com, rppt@linux.vnet.ibm.com,
graf@amazon.de, mgross@linux.intel.com, kuzuno@gmail.com,
alexandre.chartre@oracle.com
Subject: [RFC][PATCH v2 13/21] x86/pti: Execute syscall functions on the kernel stack
Date: Mon, 16 Nov 2020 15:47:49 +0100 [thread overview]
Message-ID: <20201116144757.1920077-14-alexandre.chartre@oracle.com> (raw)
In-Reply-To: <20201116144757.1920077-1-alexandre.chartre@oracle.com>
During a syscall, the kernel is entered and it switches the stack
to the PTI stack which is mapped both in the kernel and in the
user page-table. When executing the syscall function, switch to
the kernel stack (which is mapped only in the kernel page-table)
so that no kernel data leak to the userland through the stack.
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
---
arch/x86/entry/common.c | 11 ++++++++++-
arch/x86/entry/entry_64.S | 1 +
arch/x86/include/asm/irq_stack.h | 3 +++
3 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 7ee15a12c115..1aba02ecb806 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -56,10 +56,19 @@ __visible noinstr void return_from_fork(struct pt_regs *regs,
static __always_inline void run_syscall(sys_call_ptr_t sysfunc,
struct pt_regs *regs)
{
+ unsigned long stack;
+
if (!sysfunc)
return;
- regs->ax = sysfunc(regs);
+ if (!pti_enabled()) {
+ regs->ax = sysfunc(regs);
+ return;
+ }
+
+ stack = (unsigned long)task_top_of_kernel_stack(current);
+ regs->ax = asm_call_syscall_on_stack((void *)(stack - 8),
+ sysfunc, regs);
}
#ifdef CONFIG_X86_64
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 29beab46bedd..6b88a0eb8975 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -771,6 +771,7 @@ SYM_FUNC_START(asm_call_on_stack_2)
SYM_FUNC_START(asm_call_on_stack_3)
SYM_INNER_LABEL(asm_call_sysvec_on_stack, SYM_L_GLOBAL)
SYM_INNER_LABEL(asm_call_irq_on_stack, SYM_L_GLOBAL)
+SYM_INNER_LABEL(asm_call_syscall_on_stack, SYM_L_GLOBAL)
/*
* Save the frame pointer unconditionally. This allows the ORC
* unwinder to handle the stack switch.
diff --git a/arch/x86/include/asm/irq_stack.h b/arch/x86/include/asm/irq_stack.h
index 359427216336..108d9da7c01c 100644
--- a/arch/x86/include/asm/irq_stack.h
+++ b/arch/x86/include/asm/irq_stack.h
@@ -5,6 +5,7 @@
#include <linux/ptrace.h>
#include <asm/processor.h>
+#include <asm/syscall.h>
#ifdef CONFIG_X86_64
static __always_inline bool irqstack_active(void)
@@ -25,6 +26,8 @@ void asm_call_sysvec_on_stack(void *sp, void (*func)(struct pt_regs *regs),
struct pt_regs *regs);
void asm_call_irq_on_stack(void *sp, void (*func)(struct irq_desc *desc),
struct irq_desc *desc);
+long asm_call_syscall_on_stack(void *sp, sys_call_ptr_t func,
+ struct pt_regs *regs);
static __always_inline void __run_on_irqstack(void (*func)(void))
{
--
2.18.4
next prev parent reply other threads:[~2020-11-16 14:47 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-16 14:47 [RFC][PATCH v2 00/21] x86/pti: Defer CR3 switch to C code Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 01/21] x86/syscall: Add wrapper for invoking syscall function Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 02/21] x86/entry: Update asm_call_on_stack to support more function arguments Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 03/21] x86/entry: Consolidate IST entry from userspace Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 04/21] x86/sev-es: Define a setup stack function for the VC idtentry Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 05/21] x86/entry: Implement ret_from_fork body with C code Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 06/21] x86/pti: Provide C variants of PTI switch CR3 macros Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 07/21] x86/entry: Fill ESPFIX stack using C code Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 08/21] x86/pti: Introduce per-task PTI trampoline stack Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 09/21] x86/pti: Function to clone page-table entries from a specified mm Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 10/21] x86/pti: Function to map per-cpu page-table entry Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 11/21] x86/pti: Extend PTI user mappings Alexandre Chartre
2020-11-16 19:48 ` Andy Lutomirski
2020-11-16 20:21 ` Alexandre Chartre
2020-11-16 23:06 ` Andy Lutomirski
2020-11-17 8:42 ` Alexandre Chartre
2020-11-17 15:49 ` Andy Lutomirski
2020-11-19 19:15 ` Thomas Gleixner
2020-11-16 14:47 ` [RFC][PATCH v2 12/21] x86/pti: Use PTI stack instead of trampoline stack Alexandre Chartre
2020-11-16 16:57 ` Andy Lutomirski
2020-11-16 18:10 ` Alexandre Chartre
2020-11-16 18:34 ` Andy Lutomirski
2020-11-16 19:37 ` Alexandre Chartre
2020-11-17 15:09 ` Alexandre Chartre
2020-11-17 15:52 ` Andy Lutomirski
2020-11-17 17:01 ` Alexandre Chartre
2020-11-19 1:49 ` Andy Lutomirski
2020-11-19 8:05 ` Alexandre Chartre
2020-11-19 12:06 ` Alexandre Chartre
2020-11-19 16:06 ` Andy Lutomirski
2020-11-19 17:02 ` Alexandre Chartre
2020-11-16 21:24 ` David Laight
2020-11-17 8:27 ` Alexandre Chartre
2020-11-19 19:10 ` Thomas Gleixner
2020-11-19 19:55 ` Alexandre Chartre
2020-11-19 21:20 ` Thomas Gleixner
2020-11-24 7:20 ` [x86/pti] 5da9e742d1: PANIC:double_fault kernel test robot
2020-11-16 14:47 ` Alexandre Chartre [this message]
2020-11-16 14:47 ` [RFC][PATCH v2 14/21] x86/pti: Execute IDT handlers on the kernel stack Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 15/21] x86/pti: Execute IDT handlers with error code " Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 16/21] x86/pti: Execute system vector handlers " Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 17/21] x86/pti: Execute page fault handler " Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 18/21] x86/pti: Execute NMI " Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 19/21] x86/pti: Defer CR3 switch to C code for IST entries Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 20/21] x86/pti: Defer CR3 switch to C code for non-IST and syscall entries Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 21/21] x86/pti: Use a different stack canary with the user and kernel page-table Alexandre Chartre
2020-11-16 16:56 ` Andy Lutomirski
2020-11-16 18:34 ` Alexandre Chartre
2020-11-16 20:17 ` [RFC][PATCH v2 00/21] x86/pti: Defer CR3 switch to C code Borislav Petkov
2020-11-17 7:56 ` Alexandre Chartre
2020-11-17 16:55 ` Borislav Petkov
2020-11-17 18:12 ` Alexandre Chartre
2020-11-17 18:28 ` Borislav Petkov
2020-11-17 19:02 ` Alexandre Chartre
2020-11-17 21:23 ` Borislav Petkov
2020-11-18 7:08 ` Alexandre Chartre
2020-11-17 21:26 ` Borislav Petkov
2020-11-18 7:41 ` Alexandre Chartre
2020-11-18 9:30 ` David Laight
2020-11-18 10:29 ` Alexandre Chartre
2020-11-18 13:22 ` David Laight
2020-11-18 17:15 ` Alexandre Chartre
2020-11-18 11:29 ` Borislav Petkov
2020-11-18 19:37 ` Alexandre Chartre
2020-11-16 20:24 ` Borislav Petkov
2020-11-17 8:19 ` Alexandre Chartre
2020-11-17 17:07 ` Borislav Petkov
2020-11-17 18:24 ` Alexandre Chartre
2020-11-19 19:32 ` Thomas Gleixner
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