1// SPDX-License-Identifier: GPL-2.0
  2
  3#include <linux/compat.h>
  4#include <linux/errno.h>
  5#include <linux/prctl.h>
  6#include <linux/random.h>
  7#include <linux/sched.h>
  8#include <asm/cpufeature.h>
  9#include <asm/pointer_auth.h>
 10
 11int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg)
 12{
 13	struct ptrauth_keys_user *keys = &tsk->thread.keys_user;
 14	unsigned long addr_key_mask = PR_PAC_APIAKEY | PR_PAC_APIBKEY |
 15				      PR_PAC_APDAKEY | PR_PAC_APDBKEY;
 16	unsigned long key_mask = addr_key_mask | PR_PAC_APGAKEY;
 17
 18	if (!system_supports_address_auth() && !system_supports_generic_auth())
 19		return -EINVAL;
 20
 21	if (is_compat_thread(task_thread_info(tsk)))
 22		return -EINVAL;
 23
 24	if (!arg) {
 25		ptrauth_keys_init_user(keys);
 26		return 0;
 27	}
 28
 29	if (arg & ~key_mask)
 30		return -EINVAL;
 31
 32	if (((arg & addr_key_mask) && !system_supports_address_auth()) ||
 33	    ((arg & PR_PAC_APGAKEY) && !system_supports_generic_auth()))
 34		return -EINVAL;
 35
 36	if (arg & PR_PAC_APIAKEY)
 37		get_random_bytes(&keys->apia, sizeof(keys->apia));
 38	if (arg & PR_PAC_APIBKEY)
 39		get_random_bytes(&keys->apib, sizeof(keys->apib));
 40	if (arg & PR_PAC_APDAKEY)
 41		get_random_bytes(&keys->apda, sizeof(keys->apda));
 42	if (arg & PR_PAC_APDBKEY)
 43		get_random_bytes(&keys->apdb, sizeof(keys->apdb));
 44	if (arg & PR_PAC_APGAKEY)
 45		get_random_bytes(&keys->apga, sizeof(keys->apga));
 46	ptrauth_keys_install_user(keys);
 47
 48	return 0;
 49}
 50
 51static u64 arg_to_enxx_mask(unsigned long arg)
 52{
 53	u64 sctlr_enxx_mask = 0;
 54
 55	WARN_ON(arg & ~PR_PAC_ENABLED_KEYS_MASK);
 56	if (arg & PR_PAC_APIAKEY)
 57		sctlr_enxx_mask |= SCTLR_ELx_ENIA;
 58	if (arg & PR_PAC_APIBKEY)
 59		sctlr_enxx_mask |= SCTLR_ELx_ENIB;
 60	if (arg & PR_PAC_APDAKEY)
 61		sctlr_enxx_mask |= SCTLR_ELx_ENDA;
 62	if (arg & PR_PAC_APDBKEY)
 63		sctlr_enxx_mask |= SCTLR_ELx_ENDB;
 64	return sctlr_enxx_mask;
 65}
 66
 67int ptrauth_set_enabled_keys(struct task_struct *tsk, unsigned long keys,
 68			     unsigned long enabled)
 69{
 70	u64 sctlr;
 71
 72	if (!system_supports_address_auth())
 73		return -EINVAL;
 74
 75	if (is_compat_thread(task_thread_info(tsk)))
 76		return -EINVAL;
 77
 78	if ((keys & ~PR_PAC_ENABLED_KEYS_MASK) || (enabled & ~keys))
 79		return -EINVAL;
 80
 81	preempt_disable();
 82	sctlr = tsk->thread.sctlr_user;
 83	sctlr &= ~arg_to_enxx_mask(keys);
 84	sctlr |= arg_to_enxx_mask(enabled);
 85	tsk->thread.sctlr_user = sctlr;
 86	if (tsk == current)
 87		update_sctlr_el1(sctlr);
 88	preempt_enable();
 89
 90	return 0;
 91}
 92
 93int ptrauth_get_enabled_keys(struct task_struct *tsk)
 94{
 95	int retval = 0;
 96
 97	if (!system_supports_address_auth())
 98		return -EINVAL;
 99
100	if (is_compat_thread(task_thread_info(tsk)))
101		return -EINVAL;
102
103	if (tsk->thread.sctlr_user & SCTLR_ELx_ENIA)
104		retval |= PR_PAC_APIAKEY;
105	if (tsk->thread.sctlr_user & SCTLR_ELx_ENIB)
106		retval |= PR_PAC_APIBKEY;
107	if (tsk->thread.sctlr_user & SCTLR_ELx_ENDA)
108		retval |= PR_PAC_APDAKEY;
109	if (tsk->thread.sctlr_user & SCTLR_ELx_ENDB)
110		retval |= PR_PAC_APDBKEY;
111
112	return retval;
113}