Atmosphere/exosphere/src/smc_user.c

/*
 * Copyright (c) 2018 Atmosphère-NX
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include <stdbool.h>
#include <stdint.h>
#include <string.h>

#include "utils.h"
#include "arm.h"
#include "configitem.h"
#include "gcm.h"
#include "masterkey.h"
#include "smc_api.h"
#include "smc_user.h"
#include "se.h"
#include "fuse.h"
#include "sealedkeys.h"
#include "userpage.h"
#include "titlekey.h"
#include "exocfg.h"

/* Globals. */
static bool g_crypt_aes_done = false;
static bool g_exp_mod_done = false;

static uint8_t g_imported_exponents[4][0x100];

static uint8_t g_rsausecase_to_cryptousecase[5] = {1, 2, 3, 5, 6};

static bool is_user_keyslot_valid(unsigned int keyslot) {
    switch (exosphere_get_target_firmware()) {
        case EXOSPHERE_TARGET_FIRMWARE_100:
        case EXOSPHERE_TARGET_FIRMWARE_200:
        case EXOSPHERE_TARGET_FIRMWARE_300:
        case EXOSPHERE_TARGET_FIRMWARE_400:
        case EXOSPHERE_TARGET_FIRMWARE_500:
            return keyslot <= 3;
        case EXOSPHERE_TARGET_FIRMWARE_600:
        case EXOSPHERE_TARGET_FIRMWARE_620:
        default:
            return keyslot <= 5;
    }
}

void set_exp_mod_done(bool done) {
    g_exp_mod_done = done;
}

bool get_exp_mod_done(void) {
    return g_exp_mod_done;
}

uint32_t exp_mod_done_handler(void) {
    set_exp_mod_done(true);

    se_trigger_interrupt();

    return 0;
}

uint32_t user_exp_mod(smc_args_t *args) {
    uint8_t modulus[0x100];
    uint8_t exponent[0x100];
    uint8_t input[0x100];

    upage_ref_t page_ref;

    /* Validate size. */
    if (args->X[4] == 0 || args->X[4] > 0x100 || (args->X[4] & 3) != 0) {
        return 2;
    }

    size_t exponent_size = (size_t)args->X[4];

    void *user_input = (void *)args->X[1];
    void *user_exponent = (void *)args->X[2];
    void *user_modulus = (void *)args->X[3];

    /* Copy user data into secure memory. */
    if (upage_init(&page_ref, user_input) == 0) {
        return 2;
    }
    if (user_copy_to_secure(&page_ref, input, user_input, 0x100) == 0) {
        return 2;
    }
    if (user_copy_to_secure(&page_ref, exponent, user_exponent, exponent_size) == 0) {
        return 2;
    }
    if (user_copy_to_secure(&page_ref, modulus, user_modulus, 0x100) == 0) {
        return 2;
    }

    set_exp_mod_done(false);
    /* Hardcode RSA keyslot 0. */
    set_rsa_keyslot(0, modulus, 0x100, exponent, exponent_size);
    se_exp_mod(0, input, 0x100, exp_mod_done_handler);

    return 0;
}

uint32_t user_get_random_bytes(smc_args_t *args) {
    uint8_t random_bytes[0x40];
    if (args->X[1] > 0x38) {
        return 2;
    }

    size_t size = (size_t)args->X[1];

    flush_dcache_range(random_bytes, random_bytes + size);
    se_generate_random(KEYSLOT_SWITCH_RNGKEY, random_bytes, size);
    flush_dcache_range(random_bytes, random_bytes + size);

    if (size != 0) {
        memcpy(&args->X[1], random_bytes, size);
    }
    return 0;
}

uint32_t user_generate_aes_kek(smc_args_t *args) {
    uint64_t wrapped_kek[2];
    uint8_t kek_source[0x10];
    uint64_t kek[2];
    uint64_t sealed_kek[2];

    wrapped_kek[0] = args->X[1];
    wrapped_kek[1] = args->X[2];

    unsigned int master_key_rev = (unsigned int)args->X[3];

    if (master_key_rev > 0) {
        master_key_rev -= 1; /* GenerateAesKek offsets by one. */
    }

    if (master_key_rev >= MASTERKEY_REVISION_MAX || master_key_rev > mkey_get_revision()) {
        return 2;
    }

    uint64_t packed_options = args->X[4];
    if (packed_options > 0xFF) {
        return 2;
    }

    /* Switched the output based on how the system was booted. */
    uint8_t mask_id = (uint8_t)((packed_options >> 1) & 3);

    /* Switches the output based on how it will be used. */
    uint8_t usecase = (uint8_t)((packed_options >> 5) & (exosphere_get_target_firmware() >= EXOSPHERE_TARGET_FIRMWARE_500 ? 7 : 3));

    /* Switched the output based on whether it should be console unique. */
    bool is_personalized = (int)(packed_options & 1);

    bool is_recovery_boot = configitem_is_recovery_boot();
    
    /* 5.0.0+ Bounds checking. */
    if (exosphere_get_target_firmware() >= EXOSPHERE_TARGET_FIRMWARE_500) {
        if (is_personalized) {
            if (master_key_rev >= MASTERKEY_REVISION_MAX || (MASTERKEY_REVISION_300 <= master_key_rev && master_key_rev < MASTERKEY_REVISION_400_410)) {
                return 2;
            }
            if (mask_id > 3 || usecase >= CRYPTOUSECASE_MAX_5X) {
                return 2;
            }
        } else {
            if (usecase >= CRYPTOUSECASE_UNK6) {
                return 2;
            }
            if (usecase == CRYPTOUSECASE_UNK5 && mask_id >= 4) {
                return 2;
            }
        }
    }

    /* Mask 2 is only allowed when booted from recovery. */
    if (mask_id == 2 && !is_recovery_boot) {
        return 2;
    }
    /* Mask 1 is only allowed when booted normally. */
    if (mask_id == 1 && is_recovery_boot) {
        return 2;
    }

    /* Masks 0, 3 are allowed all the time. */

    const uint8_t kek_seeds[7][0x10] = {
        {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
        {0xA2, 0xAB, 0xBF, 0x9C, 0x92, 0x2F, 0xBB, 0xE3, 0x78, 0x79, 0x9B, 0xC0, 0xCC, 0xEA, 0xA5, 0x74},
        {0x57, 0xE2, 0xD9, 0x45, 0xE4, 0x92, 0xF4, 0xFD, 0xC3, 0xF9, 0x86, 0x38, 0x89, 0x78, 0x9F, 0x3C},
        {0xE5, 0x4D, 0x9A, 0x02, 0xF0, 0x4F, 0x5F, 0xA8, 0xAD, 0x76, 0x0A, 0xF6, 0x32, 0x95, 0x59, 0xBB},
        /* 5.0.0+ KEK seeds. */
        {0x59, 0xD9, 0x31, 0xF4, 0xA7, 0x97, 0xB8, 0x14, 0x40, 0xD6, 0xA2, 0x60, 0x2B, 0xED, 0x15, 0x31},
        {0xFD, 0x6A, 0x25, 0xE5, 0xD8, 0x38, 0x7F, 0x91, 0x49, 0xDA, 0xF8, 0x59, 0xA8, 0x28, 0xE6, 0x75},
        {0x89, 0x96, 0x43, 0x9A, 0x7C, 0xD5, 0x59, 0x55, 0x24, 0xD5, 0x24, 0x18, 0xAB, 0x6C, 0x04, 0x61}
    };
    const uint8_t kek_masks[4][0x10] = {
        {0x4D, 0x87, 0x09, 0x86, 0xC4, 0x5D, 0x20, 0x72, 0x2F, 0xBA, 0x10, 0x53, 0xDA, 0x92, 0xE8, 0xA9},
        {0x25, 0x03, 0x31, 0xFB, 0x25, 0x26, 0x0B, 0x79, 0x8C, 0x80, 0xD2, 0x69, 0x98, 0xE2, 0x22, 0x77},
        {0x76, 0x14, 0x1D, 0x34, 0x93, 0x2D, 0xE1, 0x84, 0x24, 0x7B, 0x66, 0x65, 0x55, 0x04, 0x65, 0x81},
        {0xAF, 0x3D, 0xB7, 0xF3, 0x08, 0xA2, 0xD8, 0xA2, 0x08, 0xCA, 0x18, 0xA8, 0x69, 0x46, 0xC9, 0x0B}
    };

    /* Create kek source. */
    for (unsigned int i = 0; i < 0x10; i++) {
        kek_source[i] = kek_seeds[usecase][i] ^ kek_masks[mask_id][i];
    }

    unsigned int keyslot;
    if (is_personalized) {
        /* Behavior changed in 4.0.0, and in 5.0.0. */
        if (exosphere_get_target_firmware() >= EXOSPHERE_TARGET_FIRMWARE_500) {
            keyslot = devkey_get_keyslot(master_key_rev);
        } else if (exosphere_get_target_firmware() == EXOSPHERE_TARGET_FIRMWARE_400) {
            if (master_key_rev >= 1) {
                keyslot = KEYSLOT_SWITCH_DEVICEKEY; /* New device key, 4.x. */
            } else {
                keyslot = KEYSLOT_SWITCH_4XOLDDEVICEKEY; /* Old device key, 4.x. */
            }
        } else {
            keyslot = KEYSLOT_SWITCH_DEVICEKEY;
        }
    } else {
        keyslot = mkey_get_keyslot(master_key_rev);
    }

    /* Derive kek. */
    decrypt_data_into_keyslot(KEYSLOT_SWITCH_TEMPKEY, keyslot, kek_source, 0x10);
    se_aes_ecb_decrypt_block(KEYSLOT_SWITCH_TEMPKEY, kek, 0x10, wrapped_kek, 0x10);


    /* Seal kek. */
    seal_key(sealed_kek, 0x10, kek, 0x10, usecase);

    args->X[1] = sealed_kek[0];
    args->X[2] = sealed_kek[1];

    return 0;
}

uint32_t user_load_aes_key(smc_args_t *args) {
    uint64_t sealed_kek[2];
    uint64_t wrapped_key[2];

    uint32_t keyslot = (uint32_t)args->X[1];
    if (!is_user_keyslot_valid(keyslot)) {
        return 2;
    }

    /* Copy keydata */
    sealed_kek[0] = args->X[2];
    sealed_kek[1] = args->X[3];
    wrapped_key[0] = args->X[4];
    wrapped_key[1] = args->X[5];

    /* Unseal the kek. */
    unseal_key(KEYSLOT_SWITCH_TEMPKEY, sealed_kek, 0x10, CRYPTOUSECASE_AES);

    /* Unwrap the key. */
    decrypt_data_into_keyslot(keyslot, KEYSLOT_SWITCH_TEMPKEY, wrapped_key, 0x10);
    return 0;
}


void set_crypt_aes_done(bool done) {
    g_crypt_aes_done = done;
}

bool get_crypt_aes_done(void) {
    return g_crypt_aes_done;
}

uint32_t crypt_aes_done_handler(void) {
    se_check_for_error();

    set_crypt_aes_done(true);

    se_trigger_interrupt();

    return 0;
}

uint32_t user_crypt_aes(smc_args_t *args) {
    uint32_t keyslot = args->X[1] & 3;
    uint32_t mode = (args->X[1] >> 4) & 3;
    
    if (exosphere_get_target_firmware() >= EXOSPHERE_TARGET_FIRMWARE_600) {
        keyslot = args->X[1] & 7;
    }

    uint64_t iv_ctr[2];
    iv_ctr[0] = args->X[2];
    iv_ctr[1] = args->X[3];

    uint32_t in_ll_paddr = (uint32_t)(args->X[4]);
    uint32_t out_ll_paddr = (uint32_t)(args->X[5]);

    size_t size = args->X[6];
    if (!is_user_keyslot_valid(keyslot) || size & 0xF) {
        return 2;
    }

    if (exosphere_get_target_firmware() >= EXOSPHERE_TARGET_FIRMWARE_500) {
        /* Disallow dma lists outside of safe range. */
        if (in_ll_paddr - 0x80000000 >= 0x3FF7F5) {
            return 2;
        }
        if (out_ll_paddr - 0x80000000 >= 0x3FF7F5) {
            return 2;
        }
    }

    set_crypt_aes_done(false);

    uint64_t result = 0;
    switch (mode) {
        case 0: /* CBC Encryption */
            se_aes_cbc_encrypt_insecure(keyslot, out_ll_paddr, in_ll_paddr, size, iv_ctr, crypt_aes_done_handler);
            result = 0;
            break;
        case 1: /* CBC Decryption */
            se_aes_cbc_decrypt_insecure(keyslot, out_ll_paddr, in_ll_paddr, size, iv_ctr, crypt_aes_done_handler);
            result = 0;
            break;
        case 2: /* CTR "Encryption" */
            se_aes_ctr_crypt_insecure(keyslot, out_ll_paddr, in_ll_paddr, size, iv_ctr, crypt_aes_done_handler);
            result = 0;
            break;
        case 3:
        default:
            result = 1;
            break;
    }

    return result;
}

uint32_t user_generate_specific_aes_key(smc_args_t *args) {
    uint64_t wrapped_key[2];
    uint8_t key[0x10];
    unsigned int master_key_rev;
    bool should_mask;

    wrapped_key[0] = args->X[1];
    wrapped_key[1] = args->X[2];

    master_key_rev = (unsigned int)args->X[3];
    if (master_key_rev > 0) {
        master_key_rev -= 1;
    }
    if (exosphere_get_target_firmware() < EXOSPHERE_TARGET_FIRMWARE_400) {
        master_key_rev = 0;
    }

    if (master_key_rev >= MASTERKEY_REVISION_MAX) {
        return 2;
    }

    if (args->X[4] > 1) {
        return 2;
    }
    should_mask = args->X[4] != 0;

    unsigned int keyslot;

    /* Behavior changed in 5.0.0. */
    if (exosphere_get_target_firmware() >= EXOSPHERE_TARGET_FIRMWARE_500) {
        keyslot = devkey_get_keyslot(master_key_rev);
    } else if (exosphere_get_target_firmware() == EXOSPHERE_TARGET_FIRMWARE_400) {
        if (master_key_rev >= 1) {
            keyslot = KEYSLOT_SWITCH_DEVICEKEY; /* New device key, 4.x. */
        } else {
            keyslot = KEYSLOT_SWITCH_4XOLDDEVICEKEY; /* Old device key, 4.x. */
        }
    } else {
        keyslot = KEYSLOT_SWITCH_DEVICEKEY;
    }

    if (fuse_get_bootrom_patch_version() < 0x7F) {
        /* On dev units, use a fixed "all-zeroes" seed. */
        /* Yes, this data really is all-zero in actual TrustZone .rodata. */
        uint8_t dev_specific_aes_key_source[0x10] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
        uint8_t dev_specific_aes_key_ctr[0x10] = {0x3C, 0xD5, 0x92, 0xEC, 0x68, 0x31, 0x4A, 0x06, 0xD4, 0x1B, 0x0C, 0xD9, 0xF6, 0x2E, 0xD9, 0xE9};
        uint8_t dev_specific_aes_key_mask[0x10] = {0xAC, 0xCA, 0x9A, 0xCA, 0xFF, 0x2E, 0xB9, 0x22, 0xCC, 0x1F, 0x4F, 0xAD, 0xDD, 0x77, 0x21, 0x1E};

        flush_dcache_range(key, key + 0x10);
        se_aes_ctr_crypt(keyslot, key, 0x10, dev_specific_aes_key_source, 0x10, dev_specific_aes_key_ctr, 0x10);
        flush_dcache_range(key, key + 0x10);

        if (should_mask) {
            for (unsigned int i = 0; i < 0x10; i++) {
                key[i] ^= dev_specific_aes_key_mask[i];
            }
        }
    } else {
        /* On retail, standard kek->key decryption. */
        uint8_t retail_specific_aes_key_source[0x10] = {0xE2, 0xD6, 0xB8, 0x7A, 0x11, 0x9C, 0xB8, 0x80, 0xE8, 0x22, 0x88, 0x8A, 0x46, 0xFB, 0xA1, 0x95};
        decrypt_data_into_keyslot(KEYSLOT_SWITCH_TEMPKEY, keyslot, retail_specific_aes_key_source, 0x10);
        se_aes_ecb_decrypt_block(KEYSLOT_SWITCH_TEMPKEY, key, 0x10, wrapped_key, 0x10);
    }


    args->X[1] = read64le(key, 0);
    args->X[2] = read64le(key, 8);
    return 0;
}

uint32_t user_compute_cmac(smc_args_t *args) {
    uint32_t keyslot = (uint32_t)args->X[1];
    void *user_address = (void *)args->X[2];
    size_t size = (size_t)args->X[3];

    uint8_t user_data[0x400];
    uint64_t result_cmac[2];
    upage_ref_t page_ref;

    /* Validate keyslot and size. */
    if (!is_user_keyslot_valid(keyslot) || args->X[3] > 0x400) {
        return 2;
    }

    if (upage_init(&page_ref, user_address) == 0 || user_copy_to_secure(&page_ref, user_data, user_address, size) == 0) {
        return 2;
    }

    flush_dcache_range(user_data, user_data + size);

    se_compute_aes_128_cmac(keyslot, result_cmac, 0x10, user_data, size);

    /* Copy CMAC out. */
    args->X[1] = result_cmac[0];
    args->X[2] = result_cmac[1];

    return 0;
}

uint32_t user_load_rsa_oaep_key(smc_args_t *args) {
    uint64_t sealed_kek[2];
    uint64_t wrapped_key[2];
    bool is_personalized;

    uint8_t user_data[0x400];
    void *user_address;
    size_t size;
    upage_ref_t page_ref;

    /* This function no longer exists in 5.x+. */
    if (exosphere_get_target_firmware() >= EXOSPHERE_TARGET_FIRMWARE_500) {
        generic_panic();
    }

    /* Copy keydata */
    sealed_kek[0] = args->X[1];
    sealed_kek[1] = args->X[2];
    if (args->X[3] > 1) {
        return 2;
    }
    is_personalized = args->X[3] != 0;
    user_address = (void *)args->X[4];
    size = (size_t)args->X[5];
    wrapped_key[0] = args->X[6];
    wrapped_key[1] = args->X[7];

    if (is_personalized && size != 0x240) {
        return 2;
    }
    if (!is_personalized && (size != 0x220 || fuse_get_bootrom_patch_version() >= 0x7F)) {
        return 2;
    }

    if (upage_init(&page_ref, user_address) == 0 || user_copy_to_secure(&page_ref, user_data, user_address, size) == 0) {
        return 2;
    }

    flush_dcache_range(user_data, user_data + size);

    /* Ensure that our private key is 0x100 bytes. */
    if (gcm_decrypt_key(user_data, size, user_data, size, sealed_kek, 0x10, wrapped_key, 0x10, CRYPTOUSECASE_RSAOAEP, is_personalized, NULL) < 0x100) {
        return 2;
    }

    memcpy(g_imported_exponents[0], user_data, 0x100);
    return 0;
}

uint32_t user_decrypt_rsa_private_key(smc_args_t *args) {
    uint64_t sealed_kek[2];
    uint64_t wrapped_key[2];
    bool is_personalized;

    uint8_t user_data[0x400];
    void *user_address;
    size_t size;
    upage_ref_t page_ref;

    /* This function no longer exists in 5.x+. */
    if (exosphere_get_target_firmware() >= EXOSPHERE_TARGET_FIRMWARE_500) {
        generic_panic();
    }

    /* Copy keydata */
    sealed_kek[0] = args->X[1];
    sealed_kek[1] = args->X[2];
    if (args->X[3] > 1) {
        return 2;
    }
    is_personalized = args->X[3] != 0;
    user_address = (void *)args->X[4];
    size = (size_t)args->X[5];
    wrapped_key[0] = args->X[6];
    wrapped_key[1] = args->X[7];

    if (size > 0x240) {
        return 2;
    }

    if (is_personalized && size < 0x31) {
        return 2;
    }
    if (!is_personalized && (size < 0x11 || fuse_get_bootrom_patch_version() >= 0x7F)) {
        return 2;
    }

    if (upage_init(&page_ref, user_address) == 0 || user_copy_to_secure(&page_ref, user_data, user_address, size) == 0) {
        return 2;
    }

    flush_dcache_range(user_data, user_data + size);

    size_t out_size;

    if ((out_size = gcm_decrypt_key(user_data, size, user_data, size, sealed_kek, 0x10, wrapped_key, 0x10, CRYPTOUSECASE_RSAPRIVATE, is_personalized, NULL)) == 0) {
        return 2;
    }

    if (secure_copy_to_user(&page_ref, user_address, user_data, size) == 0) {
        return 2;
    }

    args->X[1] = out_size;
    return 0;
}

uint32_t user_load_secure_exp_mod_key(smc_args_t *args) {
    uint64_t sealed_kek[2];
    uint64_t wrapped_key[2];
    bool is_personalized;

    uint8_t user_data[0x400];
    void *user_address;
    size_t size;
    upage_ref_t page_ref;

    /* This function no longer exists in 5.x+. */
    if (exosphere_get_target_firmware() >= EXOSPHERE_TARGET_FIRMWARE_500) {
        generic_panic();
    }

    /* Copy keydata */
    sealed_kek[0] = args->X[1];
    sealed_kek[1] = args->X[2];
    if (args->X[3] > 1) {
        return 2;
    }
    is_personalized = args->X[3] != 0;
    user_address = (void *)args->X[4];
    size = (size_t)args->X[5];
    wrapped_key[0] = args->X[6];
    wrapped_key[1] = args->X[7];

    if (is_personalized && size != 0x130) {
        return 2;
    }
    if (!is_personalized && (size != 0x110 || fuse_get_bootrom_patch_version() >= 0x7F)) {
        return 2;
    }

    if (upage_init(&page_ref, user_address) == 0 || user_copy_to_secure(&page_ref, user_data, user_address, size) == 0) {
        return 2;
    }

    flush_dcache_range(user_data, user_data + size);

    size_t out_size;

    /* Ensure that our key is non-zero bytes. */
    if ((out_size = gcm_decrypt_key(user_data, size, user_data, size, sealed_kek, 0x10, wrapped_key, 0x10, CRYPTOUSECASE_SECUREEXPMOD, is_personalized, NULL)) == 0) {
        return 2;
    }

    /* Copy key to global. */
    if (out_size <= 0x100) {
        memcpy(g_imported_exponents[1], user_data, out_size);
    } else {
        memcpy(g_imported_exponents[1], user_data, 0x100);
    }

    return 0;
}

uint32_t user_secure_exp_mod(smc_args_t *args) {
    uint8_t modulus[0x100];
    uint8_t input[0x100];

    upage_ref_t page_ref;

    void *user_input = (void *)args->X[1];
    void *user_modulus = (void *)args->X[2];

    unsigned int exponent_id = 1;
    if (exosphere_get_target_firmware() >= EXOSPHERE_TARGET_FIRMWARE_500) {
        switch (args->X[3]) {
            case 0:
                exponent_id = 1;
                break;
            case 1:
                exponent_id = 2;
                break;
            case 2:
                exponent_id = 3;
                break;
            default:
                return 2;
        }
    }

    /* Copy user data into secure memory. */
    if (upage_init(&page_ref, user_input) == 0) {
        return 2;
    }
    if (user_copy_to_secure(&page_ref, input, user_input, 0x100) == 0) {
        return 2;
    }
    if (user_copy_to_secure(&page_ref, modulus, user_modulus, 0x100) == 0) {
        return 2;
    }

    set_exp_mod_done(false);
    /* Hardcode RSA keyslot 0. */
    set_rsa_keyslot(0, modulus, 0x100, g_imported_exponents[exponent_id], 0x100);
    se_exp_mod(0, input, 0x100, exp_mod_done_handler);

    return 0;
}

uint32_t user_unwrap_rsa_oaep_wrapped_titlekey(smc_args_t *args) {
    uint8_t modulus[0x100];
    uint8_t wrapped_key[0x100];

    upage_ref_t page_ref;

    void *user_wrapped_key = (void *)args->X[1];
    void *user_modulus = (void *)args->X[2];
    unsigned int option = (unsigned int)args->X[7];
    unsigned int master_key_rev;
    unsigned int titlekey_type;
    if (exosphere_get_target_firmware() >= EXOSPHERE_TARGET_FIRMWARE_600) {
        master_key_rev = option & 0x3F;
        titlekey_type = (option >> 6) & 1;
    } else {
        master_key_rev = option;
        titlekey_type = 0;
    }

    if(master_key_rev > 0) {
        master_key_rev -= 1;
    }

    if (exosphere_get_target_firmware() >= EXOSPHERE_TARGET_FIRMWARE_300) {
        if (master_key_rev >= MASTERKEY_REVISION_MAX) {
            return 2;
        }
    } else {
        master_key_rev = 0;
    }

    /* Copy user data into secure memory. */
    if (upage_init(&page_ref, user_wrapped_key) == 0) {
        return 2;
    }
    if (user_copy_to_secure(&page_ref, wrapped_key, user_wrapped_key, 0x100) == 0) {
        return 2;
    }
    if (user_copy_to_secure(&page_ref, modulus, user_modulus, 0x100) == 0) {
        return 2;
    }

    set_exp_mod_done(false);

    /* Expected label_hash occupies args->X[3] to args->X[6]. */
    tkey_set_expected_label_hash(&args->X[3]);

    tkey_set_master_key_rev(master_key_rev);
    tkey_set_type(titlekey_type);

    /* Hardcode RSA keyslot 0. */
    set_rsa_keyslot(0, modulus, 0x100, g_imported_exponents[0], 0x100);
    se_exp_mod(0, wrapped_key, 0x100, exp_mod_done_handler);

    return 0;

}

uint32_t user_load_titlekey(smc_args_t *args) {
    uint64_t sealed_titlekey[2];

    uint32_t keyslot = (uint32_t)args->X[1];
    if (!is_user_keyslot_valid(keyslot)) {
        return 2;
    }

    /* Copy keydata */
    sealed_titlekey[0] = args->X[2];
    sealed_titlekey[1] = args->X[3];

    /* Unseal the key. */
    unseal_titlekey(keyslot, sealed_titlekey, 0x10);
    return 0;

}

uint32_t user_unwrap_aes_wrapped_titlekey(smc_args_t *args) {
    uint64_t aes_wrapped_titlekey[2];
    uint8_t titlekey[0x10];
    uint64_t sealed_titlekey[2];

    aes_wrapped_titlekey[0] = args->X[1];
    aes_wrapped_titlekey[1] = args->X[2];
    unsigned int master_key_rev = (unsigned int)args->X[3];

    if (master_key_rev > 0) {
        master_key_rev -= 1;
    }
    if (exosphere_get_target_firmware() >= EXOSPHERE_TARGET_FIRMWARE_300) {
        if (master_key_rev >= MASTERKEY_REVISION_MAX) {
            return 2;
        }
    } else {
        master_key_rev = 0;
    }

    tkey_set_master_key_rev(master_key_rev);
    tkey_set_type(0);

    tkey_aes_unwrap(titlekey, 0x10, aes_wrapped_titlekey, 0x10);
    seal_titlekey(sealed_titlekey, 0x10, titlekey, 0x10);

    args->X[1] = sealed_titlekey[0];
    args->X[2] = sealed_titlekey[1];

    return 0; /* FIXME: what should we return there */
}


uint32_t user_encrypt_rsa_key_for_import(smc_args_t *args) {
    uint64_t in_sealed_kek[2];
    uint64_t out_sealed_kek[2];
    uint64_t in_wrapped_key[2];
    uint64_t out_wrapped_key[2];
    uint8_t usecase;

    uint8_t user_data[0x400];
    void *user_address;
    void *user_in_kek;
    void *user_out_kek;
    void *user_in_key;
    void *user_out_key;
    size_t size;
    upage_ref_t page_ref;

    /* Copy keydata */
    user_in_kek = (void *)args->X[1];
    user_out_kek = (void *)args->X[2];
    usecase = args->X[3] & 7;
    user_address = (void *)args->X[4];
    size = (size_t)args->X[5];
    user_in_key = (void *)args->X[6];
    user_out_key = (void *)args->X[7];

    if (usecase > CRYPTOUSECASE_RSAIMPORT) {
        return 2;
    } 
    if (usecase == 0) {
        if (size < 0x31 || size > 0x240) {
            return 2;
        }
    } else if (size < 0x130 || size > 0x240) {
        return 2;
    }

    if (upage_init(&page_ref, user_address) == 0
     || user_copy_to_secure(&page_ref, user_data, user_address, size) == 0
     || user_copy_to_secure(&page_ref, in_sealed_kek, user_in_kek, 0x10) == 0
     || user_copy_to_secure(&page_ref, out_sealed_kek, user_out_kek, 0x10) == 0
     || user_copy_to_secure(&page_ref, in_wrapped_key, user_in_key, 0x10) == 0
     || user_copy_to_secure(&page_ref, out_wrapped_key, user_out_key, 0x10) == 0) {
        return 2;
    }

    flush_dcache_range(user_data, user_data + size);

    size_t out_size;

    uint8_t device_id_high;

    if ((out_size = gcm_decrypt_key(user_data, size, user_data, size, in_sealed_kek, 0x10, in_wrapped_key, 0x10, CRYPTOUSECASE_RSAIMPORT, true, &device_id_high)) == 0) {
        return 2;
    }

    gcm_encrypt_key(user_data, size, user_data, size - 0x30, out_sealed_kek, 0x10, out_wrapped_key, 0x10, g_rsausecase_to_cryptousecase[usecase], device_id_high);

    if (secure_copy_to_user(&page_ref, user_address, user_data, size) == 0) {
        return 2;
    } 

    return 0;
}

uint32_t user_decrypt_or_import_rsa_key(smc_args_t *args) {
    uint64_t sealed_kek[2];
    uint64_t wrapped_key[2];
    uint8_t usecase;

    uint8_t user_data[0x400];
    void *user_address;
    size_t size;
    upage_ref_t page_ref;

    /* This function only exists in 5.x+. */
    if (exosphere_get_target_firmware() < EXOSPHERE_TARGET_FIRMWARE_500) {
        generic_panic();
    }

    /* Copy keydata */
    sealed_kek[0] = args->X[1];
    sealed_kek[1] = args->X[2];
    usecase = args->X[3] & 7;
    user_address = (void *)args->X[4];
    size = (size_t)args->X[5];
    wrapped_key[0] = args->X[6];
    wrapped_key[1] = args->X[7];

    if (usecase > CRYPTOUSECASE_RSAIMPORT) {
        return 2;
    } 
    if (usecase == 0) {
        if (size < 0x31 || size > 0x240) {
            return 2;
        }
    } else if (size < 0x130 || size > 0x240) {
        return 2;
    }

    if (upage_init(&page_ref, user_address) == 0 || user_copy_to_secure(&page_ref, user_data, user_address, size) == 0) {
        return 2;
    }

    flush_dcache_range(user_data, user_data + size);

    size_t out_size;

    if ((out_size = gcm_decrypt_key(user_data, size, user_data, size, sealed_kek, 0x10, wrapped_key, 0x10, g_rsausecase_to_cryptousecase[usecase], true, NULL)) == 0) {
        return 2;
    }

    unsigned int exponent_id;

    switch (usecase) {
        case 0:
            if (secure_copy_to_user(&page_ref, user_address, user_data, size) == 0) {
                return 2;
            } 
            return 0;
        case 1:
            exponent_id = 1;
            break;
        case 2:
            exponent_id = 0;
            break;
        case 3:
            exponent_id = 2;
            break;
        case 4:
            exponent_id = 3;
            break;
        default:
            generic_panic();
    }

    /* Copy key to global. */
    memcpy(g_imported_exponents[exponent_id], user_data, 0x100);
    return 0;

}