ec6e822d1a
When pointer authentication is in use, data/instruction pointers have a number of PAC bits inserted into them. The number and position of these bits depends on the configured TCR_ELx.TxSZ and whether tagging is enabled. ARMv8.3 allows tagging to differ for instruction and data pointers. For userspace debuggers to unwind the stack and/or to follow pointer chains, they need to be able to remove the PAC bits before attempting to use a pointer. This patch adds a new structure with masks describing the location of the PAC bits in userspace instruction and data pointers (i.e. those addressable via TTBR0), which userspace can query via PTRACE_GETREGSET. By clearing these bits from pointers (and replacing them with the value of bit 55), userspace can acquire the PAC-less versions. This new regset is exposed when the kernel is built with (user) pointer authentication support, and the address authentication feature is enabled. Otherwise, the regset is hidden. Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Will Deacon <will.deacon@arm.com> [will: Fix to use vabits_user instead of VA_BITS and rename macro] Signed-off-by: Will Deacon <will.deacon@arm.com>
87 lines
2.4 KiB
C
87 lines
2.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
#ifndef __ASM_POINTER_AUTH_H
|
|
#define __ASM_POINTER_AUTH_H
|
|
|
|
#include <linux/bitops.h>
|
|
#include <linux/random.h>
|
|
|
|
#include <asm/cpufeature.h>
|
|
#include <asm/memory.h>
|
|
#include <asm/sysreg.h>
|
|
|
|
#ifdef CONFIG_ARM64_PTR_AUTH
|
|
/*
|
|
* Each key is a 128-bit quantity which is split across a pair of 64-bit
|
|
* registers (Lo and Hi).
|
|
*/
|
|
struct ptrauth_key {
|
|
unsigned long lo, hi;
|
|
};
|
|
|
|
/*
|
|
* We give each process its own keys, which are shared by all threads. The keys
|
|
* are inherited upon fork(), and reinitialised upon exec*().
|
|
*/
|
|
struct ptrauth_keys {
|
|
struct ptrauth_key apia;
|
|
struct ptrauth_key apib;
|
|
struct ptrauth_key apda;
|
|
struct ptrauth_key apdb;
|
|
struct ptrauth_key apga;
|
|
};
|
|
|
|
static inline void ptrauth_keys_init(struct ptrauth_keys *keys)
|
|
{
|
|
if (system_supports_address_auth()) {
|
|
get_random_bytes(&keys->apia, sizeof(keys->apia));
|
|
get_random_bytes(&keys->apib, sizeof(keys->apib));
|
|
get_random_bytes(&keys->apda, sizeof(keys->apda));
|
|
get_random_bytes(&keys->apdb, sizeof(keys->apdb));
|
|
}
|
|
|
|
if (system_supports_generic_auth())
|
|
get_random_bytes(&keys->apga, sizeof(keys->apga));
|
|
}
|
|
|
|
#define __ptrauth_key_install(k, v) \
|
|
do { \
|
|
struct ptrauth_key __pki_v = (v); \
|
|
write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1); \
|
|
write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1); \
|
|
} while (0)
|
|
|
|
static inline void ptrauth_keys_switch(struct ptrauth_keys *keys)
|
|
{
|
|
if (system_supports_address_auth()) {
|
|
__ptrauth_key_install(APIA, keys->apia);
|
|
__ptrauth_key_install(APIB, keys->apib);
|
|
__ptrauth_key_install(APDA, keys->apda);
|
|
__ptrauth_key_install(APDB, keys->apdb);
|
|
}
|
|
|
|
if (system_supports_generic_auth())
|
|
__ptrauth_key_install(APGA, keys->apga);
|
|
}
|
|
|
|
/*
|
|
* 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_user)
|
|
|
|
#define ptrauth_thread_init_user(tsk) \
|
|
do { \
|
|
struct task_struct *__ptiu_tsk = (tsk); \
|
|
ptrauth_keys_init(&__ptiu_tsk->thread_info.keys_user); \
|
|
ptrauth_keys_switch(&__ptiu_tsk->thread_info.keys_user); \
|
|
} while (0)
|
|
|
|
#define ptrauth_thread_switch(tsk) \
|
|
ptrauth_keys_switch(&(tsk)->thread_info.keys_user)
|
|
|
|
#else /* CONFIG_ARM64_PTR_AUTH */
|
|
#define ptrauth_thread_init_user(tsk)
|
|
#define ptrauth_thread_switch(tsk)
|
|
#endif /* CONFIG_ARM64_PTR_AUTH */
|
|
|
|
#endif /* __ASM_POINTER_AUTH_H */
|