diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index 9336516430a1..166b1ed9a9c0 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -6,6 +6,7 @@ #include #include #include +#include #include #include #include @@ -149,6 +150,61 @@ static __always_inline long syscall_enter_from_user_mode_work(struct pt_regs *re return syscall; } +/** + * enter_from_user_mode_randomize_stack - Establish state and add stack randomization + * before invoking syscall_enter_from_user_mode_work() + * @regs: Pointer to currents pt_regs + * + * Invoked from architecture specific syscall entry code with interrupts + * disabled. The calling code has to be non-instrumentable. When the function + * returns all state is correct, interrupts are still disabled and the + * subsequent functions can be instrumented. + * + * Implemented as a macro so that the stack randomization is effective + * throughout the function in which it is invoked. An inline would only make it + * effective in the scope of the inline function. + */ +#define enter_from_user_mode_randomize_stack(regs) \ +do { \ + enter_from_user_mode(regs); \ + instrumentation_begin(); \ + add_random_kstack_offset_irqsoff(); \ + instrumentation_end(); \ +} while (0) + +/** + * syscall_enter_from_user_mode_randomize_stack - Establish state and check and handle work + * before invoking a syscall + * @regs: Pointer to currents pt_regs + * @syscall: The syscall number + * + * Invoked from architecture specific syscall entry code with interrupts + * disabled. The calling code has to be non-instrumentable. When the + * function returns all state is correct, interrupts are enabled and the + * subsequent functions can be instrumented. + * + * This is the combination of enter_from_user_mode_randomize_stack() and + * syscall_enter_from_user_mode_work() to be used when there is no + * architecture specific work to be done between the two. + * + * Returns: The original or a modified syscall number. See + * syscall_enter_from_user_mode_work() for further explanation. + * + * Implemented as a macro to make stack randomization effective in the calling + * scope. + */ +#define syscall_enter_from_user_mode_randomize_stack(regs, syscall) \ +({ \ + enter_from_user_mode_randomize_stack(regs); \ + \ + instrumentation_begin(); \ + local_irq_enable(); \ + long _ret = syscall_enter_from_user_mode_work(regs, syscall); \ + instrumentation_end(); \ + \ + _ret; \ +}) + /** * syscall_enter_from_user_mode - Establish state and check and handle work * before invoking a syscall