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We currently enable ptrauth for userspace, but do not use it within the kernel. We're going to enable it for the kernel, and will need to manage a separate set of ptrauth keys for the kernel. We currently keep all 5 keys in struct ptrauth_keys. However, as the kernel will only need to use 1 key, it is a bit wasteful to allocate a whole ptrauth_keys struct for every thread. Therefore, a subsequent patch will define a separate struct, with only 1 key, for the kernel. In preparation for that, rename the existing struct (and associated macros and functions) to reflect that they are specific to userspace. Acked-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> [Amit: Re-positioned the patch to reduce the diff] Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
98 lines
2.7 KiB
C
98 lines
2.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_POINTER_AUTH_H
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#define __ASM_POINTER_AUTH_H
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#include <linux/bitops.h>
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#include <linux/random.h>
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#include <asm/cpufeature.h>
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#include <asm/memory.h>
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#include <asm/sysreg.h>
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#ifdef CONFIG_ARM64_PTR_AUTH
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/*
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* Each key is a 128-bit quantity which is split across a pair of 64-bit
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* registers (Lo and Hi).
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*/
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struct ptrauth_key {
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unsigned long lo, hi;
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};
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/*
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* We give each process its own keys, which are shared by all threads. The keys
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* are inherited upon fork(), and reinitialised upon exec*().
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*/
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struct ptrauth_keys_user {
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struct ptrauth_key apia;
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struct ptrauth_key apib;
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struct ptrauth_key apda;
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struct ptrauth_key apdb;
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struct ptrauth_key apga;
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};
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static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
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{
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if (system_supports_address_auth()) {
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get_random_bytes(&keys->apia, sizeof(keys->apia));
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get_random_bytes(&keys->apib, sizeof(keys->apib));
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get_random_bytes(&keys->apda, sizeof(keys->apda));
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get_random_bytes(&keys->apdb, sizeof(keys->apdb));
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}
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if (system_supports_generic_auth())
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get_random_bytes(&keys->apga, sizeof(keys->apga));
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}
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#define __ptrauth_key_install(k, v) \
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do { \
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struct ptrauth_key __pki_v = (v); \
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write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1); \
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write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1); \
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} while (0)
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static inline void ptrauth_keys_switch_user(struct ptrauth_keys_user *keys)
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{
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if (system_supports_address_auth()) {
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__ptrauth_key_install(APIA, keys->apia);
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__ptrauth_key_install(APIB, keys->apib);
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__ptrauth_key_install(APDA, keys->apda);
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__ptrauth_key_install(APDB, keys->apdb);
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}
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if (system_supports_generic_auth())
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__ptrauth_key_install(APGA, keys->apga);
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}
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extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
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/*
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* The EL0 pointer bits used by a pointer authentication code.
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* This is dependent on TBI0 being enabled, or bits 63:56 would also apply.
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*/
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#define ptrauth_user_pac_mask() GENMASK(54, vabits_actual)
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/* Only valid for EL0 TTBR0 instruction pointers */
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static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
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{
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return ptr & ~ptrauth_user_pac_mask();
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}
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#define ptrauth_thread_init_user(tsk) \
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do { \
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struct task_struct *__ptiu_tsk = (tsk); \
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ptrauth_keys_init_user(&__ptiu_tsk->thread.keys_user); \
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ptrauth_keys_switch_user(&__ptiu_tsk->thread.keys_user); \
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} while (0)
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#define ptrauth_thread_switch(tsk) \
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ptrauth_keys_switch_user(&(tsk)->thread.keys_user)
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#else /* CONFIG_ARM64_PTR_AUTH */
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#define ptrauth_prctl_reset_keys(tsk, arg) (-EINVAL)
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#define ptrauth_strip_insn_pac(lr) (lr)
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#define ptrauth_thread_init_user(tsk)
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#define ptrauth_thread_switch(tsk)
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#endif /* CONFIG_ARM64_PTR_AUTH */
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#endif /* __ASM_POINTER_AUTH_H */
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