arm64: mask PAC bits of __builtin_return_address
Functions like vmap() record how much memory has been allocated by their callers, and callers are identified using __builtin_return_address(). Once the kernel is using pointer-auth the return address will be signed. This means it will not match any kernel symbol, and will vary between threads even for the same caller. The output of /proc/vmallocinfo in this case may look like, 0x(____ptrval____)-0x(____ptrval____) 20480 0x86e28000100e7c60 pages=4 vmalloc N0=4 0x(____ptrval____)-0x(____ptrval____) 20480 0x86e28000100e7c60 pages=4 vmalloc N0=4 0x(____ptrval____)-0x(____ptrval____) 20480 0xc5c78000100e7c60 pages=4 vmalloc N0=4 The above three 64bit values should be the same symbol name and not different LR values. Use the pre-processor to add logic to clear the PAC to __builtin_return_address() callers. This patch adds a new file asm/compiler.h and is transitively included via include/compiler_types.h on the compiler command line so it is guaranteed to be loaded and the users of this macro will not find a wrong version. Helper macros ptrauth_kernel_pac_mask/ptrauth_clear_pac are created for this purpose and added in this file. Existing macro ptrauth_user_pac_mask moved from asm/pointer_auth.h. Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> Reviewed-by: James Morse <james.morse@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
parent
2832158233
commit
689eae42af
|
@ -118,6 +118,7 @@ config ARM64
|
||||||
select HAVE_ALIGNED_STRUCT_PAGE if SLUB
|
select HAVE_ALIGNED_STRUCT_PAGE if SLUB
|
||||||
select HAVE_ARCH_AUDITSYSCALL
|
select HAVE_ARCH_AUDITSYSCALL
|
||||||
select HAVE_ARCH_BITREVERSE
|
select HAVE_ARCH_BITREVERSE
|
||||||
|
select HAVE_ARCH_COMPILER_H
|
||||||
select HAVE_ARCH_HUGE_VMAP
|
select HAVE_ARCH_HUGE_VMAP
|
||||||
select HAVE_ARCH_JUMP_LABEL
|
select HAVE_ARCH_JUMP_LABEL
|
||||||
select HAVE_ARCH_JUMP_LABEL_RELATIVE
|
select HAVE_ARCH_JUMP_LABEL_RELATIVE
|
||||||
|
|
24
arch/arm64/include/asm/compiler.h
Normal file
24
arch/arm64/include/asm/compiler.h
Normal file
|
@ -0,0 +1,24 @@
|
||||||
|
/* SPDX-License-Identifier: GPL-2.0 */
|
||||||
|
#ifndef __ASM_COMPILER_H
|
||||||
|
#define __ASM_COMPILER_H
|
||||||
|
|
||||||
|
#if defined(CONFIG_ARM64_PTR_AUTH)
|
||||||
|
|
||||||
|
/*
|
||||||
|
* The EL0/EL1 pointer bits used by a pointer authentication code.
|
||||||
|
* This is dependent on TBI0/TBI1 being enabled, or bits 63:56 would also apply.
|
||||||
|
*/
|
||||||
|
#define ptrauth_user_pac_mask() GENMASK_ULL(54, vabits_actual)
|
||||||
|
#define ptrauth_kernel_pac_mask() GENMASK_ULL(63, vabits_actual)
|
||||||
|
|
||||||
|
/* Valid for EL0 TTBR0 and EL1 TTBR1 instruction pointers */
|
||||||
|
#define ptrauth_clear_pac(ptr) \
|
||||||
|
((ptr & BIT_ULL(55)) ? (ptr | ptrauth_kernel_pac_mask()) : \
|
||||||
|
(ptr & ~ptrauth_user_pac_mask()))
|
||||||
|
|
||||||
|
#define __builtin_return_address(val) \
|
||||||
|
(void *)(ptrauth_clear_pac((unsigned long)__builtin_return_address(val)))
|
||||||
|
|
||||||
|
#endif /* CONFIG_ARM64_PTR_AUTH */
|
||||||
|
|
||||||
|
#endif /* __ASM_COMPILER_H */
|
|
@ -68,16 +68,9 @@ static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kerne
|
||||||
|
|
||||||
extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
|
extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
|
||||||
|
|
||||||
/*
|
|
||||||
* The EL0 pointer bits used by a pointer authentication code.
|
|
||||||
* This is dependent on TBI0 being enabled, or bits 63:56 would also apply.
|
|
||||||
*/
|
|
||||||
#define ptrauth_user_pac_mask() GENMASK(54, vabits_actual)
|
|
||||||
|
|
||||||
/* Only valid for EL0 TTBR0 instruction pointers */
|
|
||||||
static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
|
static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
|
||||||
{
|
{
|
||||||
return ptr & ~ptrauth_user_pac_mask();
|
return ptrauth_clear_pac(ptr);
|
||||||
}
|
}
|
||||||
|
|
||||||
#define ptrauth_thread_init_user(tsk) \
|
#define ptrauth_thread_init_user(tsk) \
|
||||||
|
|
Loading…
Reference in a new issue