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Message-Id: <20180718211013.14512-2-labbott@redhat.com>
Date: Wed, 18 Jul 2018 14:10:12 -0700
From: Laura Abbott <labbott@...hat.com>
To: Alexander Popov <alex.popov@...ux.com>,
Kees Cook <keescook@...omium.org>,
Mark Rutland <mark.rutland@....com>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc: Laura Abbott <labbott@...hat.com>,
kernel-hardening@...ts.openwall.com,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Will Deacon <will.deacon@....com>,
Catalin Marinas <catalin.marinas@....com>
Subject: [PATCH 1/2] arm64: Introduce current_stack_type
In preparation for enabling the stackleak plugin on arm64,
we need a way to get the bounds of the current stack.
Introduce a new primitive current_stack_type which is similar
to x86's get_stack_info. Utilize that to rework
on_accessible_stack slightly as well.
Signed-off-by: Laura Abbott <labbott@...hat.com>
---
So this did end up looking quite a bit like get_stack_info but I didn't
really see the need to integrate this more than this. I do think
actually enumerating the types makes things a bit cleaner.
---
arch/arm64/include/asm/sdei.h | 8 ++-
arch/arm64/include/asm/stacktrace.h | 94 ++++++++++++++++++++++++-----
arch/arm64/kernel/ptrace.c | 2 +-
arch/arm64/kernel/sdei.c | 21 ++++++-
4 files changed, 103 insertions(+), 22 deletions(-)
diff --git a/arch/arm64/include/asm/sdei.h b/arch/arm64/include/asm/sdei.h
index e073e6886685..34f7b203845b 100644
--- a/arch/arm64/include/asm/sdei.h
+++ b/arch/arm64/include/asm/sdei.h
@@ -40,15 +40,17 @@ asmlinkage unsigned long __sdei_handler(struct pt_regs *regs,
unsigned long sdei_arch_get_entry_point(int conduit);
#define sdei_arch_get_entry_point(x) sdei_arch_get_entry_point(x)
-bool _on_sdei_stack(unsigned long sp);
-static inline bool on_sdei_stack(unsigned long sp)
+bool _on_sdei_stack(unsigned long sp, unsigned long *, unsigned long *);
+static inline bool on_sdei_stack(unsigned long sp,
+ unsigned long *stack_low,
+ unsigned long *stack_high)
{
if (!IS_ENABLED(CONFIG_VMAP_STACK))
return false;
if (!IS_ENABLED(CONFIG_ARM_SDE_INTERFACE))
return false;
if (in_nmi())
- return _on_sdei_stack(sp);
+ return _on_sdei_stack(sp, stack_low, stack_high);
return false;
}
diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h
index 902f9edacbea..9855a0425e64 100644
--- a/arch/arm64/include/asm/stacktrace.h
+++ b/arch/arm64/include/asm/stacktrace.h
@@ -39,7 +39,9 @@ extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk);
DECLARE_PER_CPU(unsigned long *, irq_stack_ptr);
-static inline bool on_irq_stack(unsigned long sp)
+static inline bool on_irq_stack(unsigned long sp,
+ unsigned long *stack_low,
+ unsigned long *stack_high)
{
unsigned long low = (unsigned long)raw_cpu_read(irq_stack_ptr);
unsigned long high = low + IRQ_STACK_SIZE;
@@ -47,47 +49,109 @@ static inline bool on_irq_stack(unsigned long sp)
if (!low)
return false;
- return (low <= sp && sp < high);
+ if (sp < low || sp >= high)
+ return false;
+
+ if (stack_low && stack_high) {
+ *stack_low = low;
+ *stack_high = high;
+ }
+
+ return true;
}
-static inline bool on_task_stack(struct task_struct *tsk, unsigned long sp)
+static inline bool on_task_stack(struct task_struct *tsk, unsigned long sp,
+ unsigned long *stack_low,
+ unsigned long *stack_high)
{
unsigned long low = (unsigned long)task_stack_page(tsk);
unsigned long high = low + THREAD_SIZE;
- return (low <= sp && sp < high);
+ if (sp < low || sp >= high)
+ return false;
+
+ if (stack_low && stack_high) {
+ *stack_low = low;
+ *stack_high = high;
+ }
+
+ return true;
}
#ifdef CONFIG_VMAP_STACK
DECLARE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack);
-static inline bool on_overflow_stack(unsigned long sp)
+static inline bool on_overflow_stack(unsigned long sp,
+ unsigned long *stack_low,
+ unsigned long *stack_high)
{
unsigned long low = (unsigned long)raw_cpu_ptr(overflow_stack);
unsigned long high = low + OVERFLOW_STACK_SIZE;
- return (low <= sp && sp < high);
+ if (sp < low || sp >= high)
+ return false;
+
+ if (stack_low && stack_high) {
+ *stack_low = low;
+ *stack_high = high;
+ }
+
+ return true;
}
#else
-static inline bool on_overflow_stack(unsigned long sp) { return false; }
+static inline bool on_overflow_stack(unsigned long sp,
+ unsigned long *stack_low,
+ unsigned long *stack_high) { return false; }
#endif
+enum stack_type {
+ STACK_TYPE_UNKNOWN,
+ STACK_TYPE_TASK,
+ STACK_TYPE_IRQ,
+ STACK_TYPE_OVERFLOW,
+ STACK_TYPE_SDEI,
+};
+
+static inline enum stack_type current_stack_type(struct task_struct *tsk,
+ unsigned long sp,
+ unsigned long *stack_low,
+ unsigned long *stack_high)
+{
+ if (on_task_stack(tsk, sp, stack_low, stack_high))
+ return STACK_TYPE_TASK;
+ if (on_irq_stack(sp, stack_low, stack_high))
+ return STACK_TYPE_IRQ;
+ if (on_overflow_stack(sp, stack_low, stack_high))
+ return STACK_TYPE_OVERFLOW;
+ if (on_sdei_stack(sp, stack_low, stack_high))
+ return STACK_TYPE_SDEI;
+ return STACK_TYPE_UNKNOWN;
+}
+
/*
* We can only safely access per-cpu stacks from current in a non-preemptible
* context.
*/
static inline bool on_accessible_stack(struct task_struct *tsk, unsigned long sp)
{
- if (on_task_stack(tsk, sp))
+ enum stack_type type;
+ unsigned long low, high;
+
+ type = current_stack_type(tsk, sp, &low, &high);
+
+ switch (type) {
+ case STACK_TYPE_TASK:
return true;
- if (tsk != current || preemptible())
+ case STACK_TYPE_IRQ:
+ case STACK_TYPE_OVERFLOW:
+ case STACK_TYPE_SDEI:
+ if (tsk != current || preemptible())
+ return false;
+ else
+ return true;
+ case STACK_TYPE_UNKNOWN:
return false;
- if (on_irq_stack(sp))
- return true;
- if (on_overflow_stack(sp))
- return true;
- if (on_sdei_stack(sp))
- return true;
+ }
return false;
}
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 5c338ce5a7fa..a6b3a2be7561 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -132,7 +132,7 @@ static bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
{
return ((addr & ~(THREAD_SIZE - 1)) ==
(kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1))) ||
- on_irq_stack(addr);
+ on_irq_stack(addr, NULL, NULL);
}
/**
diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c
index 6b8d90d5ceae..8e18913a53fd 100644
--- a/arch/arm64/kernel/sdei.c
+++ b/arch/arm64/kernel/sdei.c
@@ -88,7 +88,9 @@ static int init_sdei_stacks(void)
return err;
}
-bool _on_sdei_stack(unsigned long sp)
+bool _on_sdei_stack(unsigned long sp,
+ unsigned long *stack_low,
+ unsigned long *stack_high)
{
unsigned long low, high;
@@ -98,13 +100,26 @@ bool _on_sdei_stack(unsigned long sp)
low = (unsigned long)raw_cpu_read(sdei_stack_critical_ptr);
high = low + SDEI_STACK_SIZE;
- if (low <= sp && sp < high)
+ if (low <= sp && sp < high) {
+ if (stack_low && stack_high) {
+ *stack_low = low;
+ *stack_high = high;
+ }
return true;
+ }
low = (unsigned long)raw_cpu_read(sdei_stack_normal_ptr);
high = low + SDEI_STACK_SIZE;
- return (low <= sp && sp < high);
+ if (low <= sp && sp < high) {
+ if (stack_low && stack_high) {
+ *stack_low = low;
+ *stack_high = high;
+ }
+ return true;
+ }
+
+ return false;
}
unsigned long sdei_arch_get_entry_point(int conduit)
--
2.17.1
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