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 14/21] x86/pti: Execute IDT handlers on the kernel stack
Date: Mon, 16 Nov 2020 15:47:50 +0100 [thread overview]
Message-ID: <20201116144757.1920077-15-alexandre.chartre@oracle.com> (raw)
In-Reply-To: <20201116144757.1920077-1-alexandre.chartre@oracle.com>
After an interrupt/exception in userland, 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 interrupt
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.
For now, only changes IDT handlers which have no argument other
than the pt_regs registers.
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
---
arch/x86/include/asm/idtentry.h | 43 +++++++++++++++++++++++++++++++--
arch/x86/kernel/cpu/mce/core.c | 2 +-
arch/x86/kernel/traps.c | 4 +--
3 files changed, 44 insertions(+), 5 deletions(-)
diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index 4b4aca2b1420..3595a31947b3 100644
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -10,10 +10,49 @@
#include <linux/hardirq.h>
#include <asm/irq_stack.h>
+#include <asm/pti.h>
bool idtentry_enter_nmi(struct pt_regs *regs);
void idtentry_exit_nmi(struct pt_regs *regs, bool irq_state);
+/*
+ * The CALL_ON_STACK_* macro call the specified function either directly
+ * if no stack is provided, or on the specified stack.
+ */
+#define CALL_ON_STACK_1(stack, func, arg1) \
+ ((stack) ? \
+ asm_call_on_stack_1(stack, \
+ (void (*)(void))(func), (void *)(arg1)) : \
+ func(arg1))
+
+/*
+ * Functions to return the top of the kernel stack if we are using the
+ * user page-table (and thus not running with the kernel stack). If we
+ * are using the kernel page-table (and so already using the kernel
+ * stack) when it returns NULL.
+ */
+static __always_inline void *pti_kernel_stack(struct pt_regs *regs)
+{
+ unsigned long stack;
+
+ if (pti_enabled() && user_mode(regs)) {
+ stack = (unsigned long)task_top_of_kernel_stack(current);
+ return (void *)(stack - 8);
+ } else {
+ return NULL;
+ }
+}
+
+/*
+ * Wrappers to run an IDT handler on the kernel stack if we are not
+ * already using this stack.
+ */
+static __always_inline
+void run_idt(void (*func)(struct pt_regs *), struct pt_regs *regs)
+{
+ CALL_ON_STACK_1(pti_kernel_stack(regs), func, regs);
+}
+
/**
* DECLARE_IDTENTRY - Declare functions for simple IDT entry points
* No error code pushed by hardware
@@ -55,7 +94,7 @@ __visible noinstr void func(struct pt_regs *regs) \
irqentry_state_t state = irqentry_enter(regs); \
\
instrumentation_begin(); \
- __##func (regs); \
+ run_idt(__##func, regs); \
instrumentation_end(); \
irqentry_exit(regs, state); \
} \
@@ -271,7 +310,7 @@ __visible noinstr void func(struct pt_regs *regs) \
instrumentation_begin(); \
__irq_enter_raw(); \
kvm_set_cpu_l1tf_flush_l1d(); \
- __##func (regs); \
+ run_idt(__##func, regs); \
__irq_exit_raw(); \
instrumentation_end(); \
irqentry_exit(regs, state); \
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 4102b866e7c0..9407c3cd9355 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -2035,7 +2035,7 @@ DEFINE_IDTENTRY_MCE_USER(exc_machine_check)
unsigned long dr7;
dr7 = local_db_save();
- exc_machine_check_user(regs);
+ run_idt(exc_machine_check_user, regs);
local_db_restore(dr7);
}
#else
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 09b22a611d99..5161385b3670 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -257,7 +257,7 @@ DEFINE_IDTENTRY_RAW(exc_invalid_op)
state = irqentry_enter(regs);
instrumentation_begin();
- handle_invalid_op(regs);
+ run_idt(handle_invalid_op, regs);
instrumentation_end();
irqentry_exit(regs, state);
}
@@ -647,7 +647,7 @@ DEFINE_IDTENTRY_RAW(exc_int3)
if (user_mode(regs)) {
irqentry_enter_from_user_mode(regs);
instrumentation_begin();
- do_int3_user(regs);
+ run_idt(do_int3_user, regs);
instrumentation_end();
irqentry_exit_to_user_mode(regs);
} else {
--
2.18.4
next prev parent reply other threads:[~2020-11-16 14:48 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 ` [RFC][PATCH v2 13/21] x86/pti: Execute syscall functions on the kernel stack Alexandre Chartre
2020-11-16 14:47 ` Alexandre Chartre [this message]
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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