// SPDX-License-Identifier: GPL-2.0

#include <linux/compat.h>
#include <linux/errno.h>
#include <linux/prctl.h>
#include <linux/random.h>
#include <linux/sched.h>
#include <asm/cpufeature.h>
#include <asm/pointer_auth.h>

int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg)
{
        struct ptrauth_keys_user *keys = &tsk->thread.keys_user;
        unsigned long addr_key_mask = PR_PAC_APIAKEY | PR_PAC_APIBKEY |
                                      PR_PAC_APDAKEY | PR_PAC_APDBKEY;
        unsigned long key_mask = addr_key_mask | PR_PAC_APGAKEY;

        if (!system_supports_address_auth() && !system_supports_generic_auth())
                return -EINVAL;

        if (is_compat_thread(task_thread_info(tsk)))
                return -EINVAL;

        if (!arg) {
                ptrauth_keys_init_user(keys);
                return 0;
        }

        if (arg & ~key_mask)
                return -EINVAL;

        if (((arg & addr_key_mask) && !system_supports_address_auth()) ||
            ((arg & PR_PAC_APGAKEY) && !system_supports_generic_auth()))
                return -EINVAL;

        if (arg & PR_PAC_APIAKEY)
                get_random_bytes(&keys->apia, sizeof(keys->apia));
        if (arg & PR_PAC_APIBKEY)
                get_random_bytes(&keys->apib, sizeof(keys->apib));
        if (arg & PR_PAC_APDAKEY)
                get_random_bytes(&keys->apda, sizeof(keys->apda));
        if (arg & PR_PAC_APDBKEY)
                get_random_bytes(&keys->apdb, sizeof(keys->apdb));
        if (arg & PR_PAC_APGAKEY)
                get_random_bytes(&keys->apga, sizeof(keys->apga));
        ptrauth_keys_install_user(keys);

        return 0;
}

static u64 arg_to_enxx_mask(unsigned long arg)
{
        u64 sctlr_enxx_mask = 0;

        WARN_ON(arg & ~PR_PAC_ENABLED_KEYS_MASK);
        if (arg & PR_PAC_APIAKEY)
                sctlr_enxx_mask |= SCTLR_ELx_ENIA;
        if (arg & PR_PAC_APIBKEY)
                sctlr_enxx_mask |= SCTLR_ELx_ENIB;
        if (arg & PR_PAC_APDAKEY)
                sctlr_enxx_mask |= SCTLR_ELx_ENDA;
        if (arg & PR_PAC_APDBKEY)
                sctlr_enxx_mask |= SCTLR_ELx_ENDB;
        return sctlr_enxx_mask;
}

int ptrauth_set_enabled_keys(struct task_struct *tsk, unsigned long keys,
                             unsigned long enabled)
{
        u64 sctlr;

        if (!system_supports_address_auth())
                return -EINVAL;

        if (is_compat_thread(task_thread_info(tsk)))
                return -EINVAL;

        if ((keys & ~PR_PAC_ENABLED_KEYS_MASK) || (enabled & ~keys))
                return -EINVAL;

        preempt_disable();
        sctlr = tsk->thread.sctlr_user;
        sctlr &= ~arg_to_enxx_mask(keys);
        sctlr |= arg_to_enxx_mask(enabled);
        tsk->thread.sctlr_user = sctlr;
        if (tsk == current)
                update_sctlr_el1(sctlr);
        preempt_enable();

        return 0;
}

int ptrauth_get_enabled_keys(struct task_struct *tsk)
{
        int retval = 0;

        if (!system_supports_address_auth())
                return -EINVAL;

        if (is_compat_thread(task_thread_info(tsk)))
                return -EINVAL;

        if (tsk->thread.sctlr_user & SCTLR_ELx_ENIA)
                retval |= PR_PAC_APIAKEY;
        if (tsk->thread.sctlr_user & SCTLR_ELx_ENIB)
                retval |= PR_PAC_APIBKEY;
        if (tsk->thread.sctlr_user & SCTLR_ELx_ENDA)
                retval |= PR_PAC_APDAKEY;
        if (tsk->thread.sctlr_user & SCTLR_ELx_ENDB)
                retval |= PR_PAC_APDBKEY;

        return retval;
}