mirror of
https://github.com/torvalds/linux
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d2e0d8f974
In the next patch, we will start reading sctlr_user from mte_update_sctlr_user and subsequently writing a new value based on the task's TCF setting and potentially the per-CPU TCF preference. This means that we need to be careful to disable preemption around any code sequences that read from sctlr_user and subsequently write to sctlr_user and/or SCTLR_EL1, so that we don't end up writing a stale value (based on the previous CPU's TCF preference) to either of them. We currently have four such sequences, in the prctl handlers for PR_SET_TAGGED_ADDR_CTRL and PR_PAC_SET_ENABLED_KEYS, as well as in the task initialization code that resets the prctl settings. Change the prctl handlers to disable preemption in the handlers themselves rather than the functions that they call, and change the task initialization code to call the respective prctl handlers instead of setting sctlr_user directly. As a result of this change, we no longer need the helper function set_task_sctlr_el1, nor does its behavior make sense any more, so remove it. Signed-off-by: Peter Collingbourne <pcc@google.com> Link: https://linux-review.googlesource.com/id/Ic0e8a0c00bb47d786c1e8011df0b7fe99bee4bb5 Link: https://lore.kernel.org/r/20210727205300.2554659-4-pcc@google.com Acked-by: Will Deacon <will@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
153 lines
4.5 KiB
C
153 lines
4.5 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/prctl.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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#define PR_PAC_ENABLED_KEYS_MASK \
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(PR_PAC_APIAKEY | PR_PAC_APIBKEY | PR_PAC_APDAKEY | PR_PAC_APDBKEY)
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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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#define __ptrauth_key_install_nosync(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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#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
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struct ptrauth_keys_kernel {
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struct ptrauth_key apia;
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};
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static __always_inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *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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}
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static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kernel *keys)
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{
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if (!system_supports_address_auth())
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return;
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__ptrauth_key_install_nosync(APIA, keys->apia);
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isb();
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}
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#endif /* CONFIG_ARM64_PTR_AUTH_KERNEL */
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static inline void ptrauth_keys_install_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_nosync(APIB, keys->apib);
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__ptrauth_key_install_nosync(APDA, keys->apda);
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__ptrauth_key_install_nosync(APDB, keys->apdb);
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}
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if (system_supports_generic_auth())
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__ptrauth_key_install_nosync(APGA, keys->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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ptrauth_keys_install_user(keys);
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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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extern int ptrauth_set_enabled_keys(struct task_struct *tsk, unsigned long keys,
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unsigned long enabled);
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extern int ptrauth_get_enabled_keys(struct task_struct *tsk);
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static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
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{
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return ptrauth_clear_pac(ptr);
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}
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static __always_inline void ptrauth_enable(void)
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{
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if (!system_supports_address_auth())
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return;
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sysreg_clear_set(sctlr_el1, 0, (SCTLR_ELx_ENIA | SCTLR_ELx_ENIB |
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SCTLR_ELx_ENDA | SCTLR_ELx_ENDB));
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isb();
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}
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#define ptrauth_suspend_exit() \
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ptrauth_keys_install_user(¤t->thread.keys_user)
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#define ptrauth_thread_init_user() \
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do { \
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ptrauth_keys_init_user(¤t->thread.keys_user); \
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\
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/* enable all keys */ \
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if (system_supports_address_auth()) \
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ptrauth_set_enabled_keys(current, \
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PR_PAC_ENABLED_KEYS_MASK, \
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PR_PAC_ENABLED_KEYS_MASK); \
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} while (0)
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#define ptrauth_thread_switch_user(tsk) \
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ptrauth_keys_install_user(&(tsk)->thread.keys_user)
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#else /* CONFIG_ARM64_PTR_AUTH */
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#define ptrauth_enable()
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#define ptrauth_prctl_reset_keys(tsk, arg) (-EINVAL)
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#define ptrauth_set_enabled_keys(tsk, keys, enabled) (-EINVAL)
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#define ptrauth_get_enabled_keys(tsk) (-EINVAL)
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#define ptrauth_strip_insn_pac(lr) (lr)
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#define ptrauth_suspend_exit()
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#define ptrauth_thread_init_user()
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#define ptrauth_thread_switch_user(tsk)
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#endif /* CONFIG_ARM64_PTR_AUTH */
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#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
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#define ptrauth_thread_init_kernel(tsk) \
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ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
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#define ptrauth_thread_switch_kernel(tsk) \
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ptrauth_keys_switch_kernel(&(tsk)->thread.keys_kernel)
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#else
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#define ptrauth_thread_init_kernel(tsk)
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#define ptrauth_thread_switch_kernel(tsk)
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#endif /* CONFIG_ARM64_PTR_AUTH_KERNEL */
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#endif /* __ASM_POINTER_AUTH_H */
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