diff options
| author | Mark Rutland <mark.rutland@arm.com> | 2022-04-27 18:31:27 +0100 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2022-05-08 01:33:09 -0700 |
| commit | 8111e67dee9ff774712cff8e34fba465c8361960 (patch) | |
| tree | f7939bb13d63ab03d22651a35e73b17a703d212a /kernel/stackleak.c | |
| parent | f171d695f3adfd8093272fa5776ef4a2c6b9cf08 (diff) | |
stackleak: add on/off stack variants
The stackleak_erase() code dynamically handles being on a task stack or
another stack. In most cases, this is a fixed property of the caller,
which the caller is aware of, as an architecture might always return
using the task stack, or might always return using a trampoline stack.
This patch adds stackleak_erase_on_task_stack() and
stackleak_erase_off_task_stack() functions which callers can use to
avoid on_thread_stack() check and associated redundant work when the
calling stack is known. The existing stackleak_erase() is retained as a
safe default.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Alexander Popov <alex.popov@linux.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220427173128.2603085-13-mark.rutland@arm.com
Diffstat (limited to 'kernel/stackleak.c')
| -rw-r--r-- | kernel/stackleak.c | 35 |
1 files changed, 32 insertions, 3 deletions
diff --git a/kernel/stackleak.c b/kernel/stackleak.c index afd54b8e10b8..c2c33d2202e9 100644 --- a/kernel/stackleak.c +++ b/kernel/stackleak.c @@ -70,7 +70,7 @@ late_initcall(stackleak_sysctls_init); #define skip_erasing() false #endif /* CONFIG_STACKLEAK_RUNTIME_DISABLE */ -static __always_inline void __stackleak_erase(void) +static __always_inline void __stackleak_erase(bool on_task_stack) { const unsigned long task_stack_low = stackleak_task_low_bound(current); const unsigned long task_stack_high = stackleak_task_high_bound(current); @@ -96,7 +96,7 @@ static __always_inline void __stackleak_erase(void) * function has a fixed-size stack frame, and the current stack pointer * doesn't change while we write poison. */ - if (on_thread_stack()) + if (on_task_stack) erase_high = current_stack_pointer; else erase_high = task_stack_high; @@ -110,12 +110,41 @@ static __always_inline void __stackleak_erase(void) current->lowest_stack = task_stack_high; } +/* + * Erase and poison the portion of the task stack used since the last erase. + * Can be called from the task stack or an entry stack when the task stack is + * no longer in use. + */ asmlinkage void noinstr stackleak_erase(void) { if (skip_erasing()) return; - __stackleak_erase(); + __stackleak_erase(on_thread_stack()); +} + +/* + * Erase and poison the portion of the task stack used since the last erase. + * Can only be called from the task stack. + */ +asmlinkage void noinstr stackleak_erase_on_task_stack(void) +{ + if (skip_erasing()) + return; + + __stackleak_erase(true); +} + +/* + * Erase and poison the portion of the task stack used since the last erase. + * Can only be called from a stack other than the task stack. + */ +asmlinkage void noinstr stackleak_erase_off_task_stack(void) +{ + if (skip_erasing()) + return; + + __stackleak_erase(false); } void __used __no_caller_saved_registers noinstr stackleak_track_stack(void) |