/*
 * (C) Copyright 2013
 * Reinhard Pfau, Guntermann & Drunck GmbH, reinhard.pfau@gdsys.cc
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */

#include <common.h>
#include <malloc.h>
#include <fs.h>
#include <i2c.h>
#include <mmc.h>
#include <tpm.h>
#include <u-boot/sha1.h>
#include <asm/byteorder.h>
#include <asm/unaligned.h>
#include <pca9698.h>

#include "hre.h"

/* other constants */
enum {
        ESDHC_BOOT_IMAGE_SIG_OFS        = 0x40,
        ESDHC_BOOT_IMAGE_SIZE_OFS       = 0x48,
        ESDHC_BOOT_IMAGE_ADDR_OFS       = 0x50,
        ESDHC_BOOT_IMAGE_TARGET_OFS     = 0x58,
        ESDHC_BOOT_IMAGE_ENTRY_OFS      = 0x60,
};

enum {
        I2C_SOC_0 = 0,
        I2C_SOC_1 = 1,
};

enum access_mode {
        HREG_NONE       = 0,
        HREG_RD         = 1,
        HREG_WR         = 2,
        HREG_RDWR       = 3,
};

/* register constants */
enum {
        FIX_HREG_DEVICE_ID_HASH = 0,
        FIX_HREG_UNUSED1        = 1,
        FIX_HREG_UNUSED2        = 2,
        FIX_HREG_VENDOR         = 3,
        COUNT_FIX_HREGS
};

static struct h_reg pcr_hregs[24];
static struct h_reg fix_hregs[COUNT_FIX_HREGS];
static struct h_reg var_hregs[8];

/* hre opcodes */
enum {
        /* opcodes w/o data */
        HRE_NOP         = 0x00,
        HRE_SYNC        = HRE_NOP,
        HRE_CHECK0      = 0x01,
        /* opcodes w/o data, w/ sync dst */
        /* opcodes w/ data */
        HRE_LOAD        = 0x81,
        /* opcodes w/data, w/sync dst */
        HRE_XOR         = 0xC1,
        HRE_AND         = 0xC2,
        HRE_OR          = 0xC3,
        HRE_EXTEND      = 0xC4,
        HRE_LOADKEY     = 0xC5,
};

/* hre errors */
enum {
        HRE_E_OK        = 0,
        HRE_E_TPM_FAILURE,
        HRE_E_INVALID_HREG,
};

static uint64_t device_id;
static uint64_t device_cl;
static uint64_t device_type;

static uint32_t platform_key_handle;

static uint32_t hre_tpm_err;
static int hre_err = HRE_E_OK;

#define IS_PCR_HREG(spec) ((spec) & 0x20)
#define IS_FIX_HREG(spec) (((spec) & 0x38) == 0x08)
#define IS_VAR_HREG(spec) (((spec) & 0x38) == 0x10)
#define HREG_IDX(spec) ((spec) & (IS_PCR_HREG(spec) ? 0x1f : 0x7))

static const uint8_t vendor[] = "Guntermann & Drunck";

/**
 * @brief get the size of a given (TPM) NV area
 * @param index NV index of the area to get size for
 * @param size  pointer to the size
 * @return 0 on success, != 0 on error
 */
static int get_tpm_nv_size(uint32_t index, uint32_t *size)
{
        uint32_t err;
        uint8_t info[72];
        uint8_t *ptr;
        uint16_t v16;

        err = tpm_get_capability(TPM_CAP_NV_INDEX, index,
                info, sizeof(info));
        if (err) {
                printf("tpm_get_capability(CAP_NV_INDEX, %08x) failed: %u\n",
                       index, err);
                return 1;
        }

        /* skip tag and nvIndex */
        ptr = info + 6;
        /* skip 2 pcr info fields */
        v16 = get_unaligned_be16(ptr);
        ptr += 2 + v16 + 1 + 20;
        v16 = get_unaligned_be16(ptr);
        ptr += 2 + v16 + 1 + 20;
        /* skip permission and flags */
        ptr += 6 + 3;

        *size = get_unaligned_be32(ptr);
        return 0;
}

/**
 * @brief search for a key by usage auth and pub key hash.
 * @param auth  usage auth of the key to search for
 * @param pubkey_digest (SHA1) hash of the pub key structure of the key
 * @param[out] handle   the handle of the key iff found
 * @return 0 if key was found in TPM; != 0 if not.
 */
static int find_key(const uint8_t auth[20], const uint8_t pubkey_digest[20],
                uint32_t *handle)
{
        uint16_t key_count;
        uint32_t key_handles[10];
        uint8_t buf[288];
        uint8_t *ptr;
        uint32_t err;
        uint8_t digest[20];
        size_t buf_len;
        unsigned int i;

        /* fetch list of already loaded keys in the TPM */
        err = tpm_get_capability(TPM_CAP_HANDLE, TPM_RT_KEY, buf, sizeof(buf));
        if (err)
                return -1;
        key_count = get_unaligned_be16(buf);
        ptr = buf + 2;
        for (i = 0; i < key_count; ++i, ptr += 4)
                key_handles[i] = get_unaligned_be32(ptr);

        /* now search a(/ the) key which we can access with the given auth */
        for (i = 0; i < key_count; ++i) {
                buf_len = sizeof(buf);
                err = tpm_get_pub_key_oiap(key_handles[i], auth, buf, &buf_len);
                if (err && err != TPM_AUTHFAIL)
                        return -1;
                if (err)
                        continue;
                sha1_csum(buf, buf_len, digest);
                if (!memcmp(digest, pubkey_digest, 20)) {
                        *handle = key_handles[i];
                        return 0;
                }
        }
        return 1;
}

/**
 * @brief read CCDM common data from TPM NV
 * @return 0 if CCDM common data was found and read, !=0 if something failed.
 */
static int read_common_data(void)
{
        uint32_t size = 0;
        uint32_t err;
        uint8_t buf[256];
        sha1_context ctx;

        if (get_tpm_nv_size(NV_COMMON_DATA_INDEX, &size) ||
            size < NV_COMMON_DATA_MIN_SIZE)
                return 1;
        err = tpm_nv_read_value(NV_COMMON_DATA_INDEX,
                buf, min(sizeof(buf), size));
        if (err) {
                printf("tpm_nv_read_value() failed: %u\n", err);
                return 1;
        }

        device_id = get_unaligned_be64(buf);
        device_cl = get_unaligned_be64(buf + 8);
        device_type = get_unaligned_be64(buf + 16);

        sha1_starts(&ctx);
        sha1_update(&ctx, buf, 24);
        sha1_finish(&ctx, fix_hregs[FIX_HREG_DEVICE_ID_HASH].digest);
        fix_hregs[FIX_HREG_DEVICE_ID_HASH].valid = true;

        platform_key_handle = get_unaligned_be32(buf + 24);

        return 0;
}

/**
 * @brief get pointer to  hash register by specification
 * @param spec  specification of a hash register
 * @return pointer to hash register or NULL if @a spec does not qualify a
 * valid hash register; NULL else.
 */
static struct h_reg *get_hreg(uint8_t spec)
{
        uint8_t idx;

        idx = HREG_IDX(spec);
        if (IS_FIX_HREG(spec)) {
                if (idx < ARRAY_SIZE(fix_hregs))
                        return fix_hregs + idx;
                hre_err = HRE_E_INVALID_HREG;
        } else if (IS_PCR_HREG(spec)) {
                if (idx < ARRAY_SIZE(pcr_hregs))
                        return pcr_hregs + idx;
                hre_err = HRE_E_INVALID_HREG;
        } else if (IS_VAR_HREG(spec)) {
                if (idx < ARRAY_SIZE(var_hregs))
                        return var_hregs + idx;
                hre_err = HRE_E_INVALID_HREG;
        }
        return NULL;
}

/**
 * @brief get pointer of a hash register by specification and usage.
 * @param spec  specification of a hash register
 * @param mode  access mode (read or write or read/write)
 * @return pointer to hash register if found and valid; NULL else.
 *
 * This func uses @a get_reg() to determine the hash register for a given spec.
 * If a register is found it is validated according to the desired access mode.
 * The value of automatic registers (PCR register and fixed registers) is
 * loaded or computed on read access.
 */
static struct h_reg *access_hreg(uint8_t spec, enum access_mode mode)
{
        struct h_reg *result;

        result = get_hreg(spec);
        if (!result)
                return NULL;

        if (mode & HREG_WR) {
                if (IS_FIX_HREG(spec)) {
                        hre_err = HRE_E_INVALID_HREG;
                        return NULL;
                }
        }
        if (mode & HREG_RD) {
                if (!result->valid) {
                        if (IS_PCR_HREG(spec)) {
                                hre_tpm_err = tpm_pcr_read(HREG_IDX(spec),
                                        result->digest, 20);
                                result->valid = (hre_tpm_err == TPM_SUCCESS);
                        } else if (IS_FIX_HREG(spec)) {
                                switch (HREG_IDX(spec)) {
                                case FIX_HREG_DEVICE_ID_HASH:
                                        read_common_data();
                                        break;
                                case FIX_HREG_VENDOR:
                                        memcpy(result->digest, vendor, 20);
                                        result->valid = true;
                                        break;
                                }
                        } else {
                                result->valid = true;
                        }
                }
                if (!result->valid) {
                        hre_err = HRE_E_INVALID_HREG;
                        return NULL;
                }
        }

        return result;
}

static void *compute_and(void *_dst, const void *_src, size_t n)
{
        uint8_t *dst = _dst;
        const uint8_t *src = _src;
        size_t i;

        for (i = n; i-- > 0; )
                *dst++ &= *src++;

        return _dst;
}

static void *compute_or(void *_dst, const void *_src, size_t n)
{
        uint8_t *dst = _dst;
        const uint8_t *src = _src;
        size_t i;

        for (i = n; i-- > 0; )
                *dst++ |= *src++;

        return _dst;
}

static void *compute_xor(void *_dst, const void *_src, size_t n)
{
        uint8_t *dst = _dst;
        const uint8_t *src = _src;
        size_t i;

        for (i = n; i-- > 0; )
                *dst++ ^= *src++;

        return _dst;
}

static void *compute_extend(void *_dst, const void *_src, size_t n)
{
        uint8_t digest[20];
        sha1_context ctx;

        sha1_starts(&ctx);
        sha1_update(&ctx, _dst, n);
        sha1_update(&ctx, _src, n);
        sha1_finish(&ctx, digest);
        memcpy(_dst, digest, min(n, sizeof(digest)));

        return _dst;
}

static int hre_op_loadkey(struct h_reg *src_reg, struct h_reg *dst_reg,
                const void *key, size_t key_size)
{
        uint32_t parent_handle;
        uint32_t key_handle;

        if (!src_reg || !dst_reg || !src_reg->valid || !dst_reg->valid)
                return -1;
        if (find_key(src_reg->digest, dst_reg->digest, &parent_handle))
                return -1;
        hre_tpm_err = tpm_load_key2_oiap(parent_handle, key, key_size,
                src_reg->digest, &key_handle);
        if (hre_tpm_err) {
                hre_err = HRE_E_TPM_FAILURE;
                return -1;
        }

        return 0;
}

/**
 * @brief executes the next opcode on the hash register engine.
 * @param[in,out] ip    pointer to the opcode (instruction pointer)
 * @param[in,out] code_size     (remaining) size of the code
 * @return new instruction pointer on success, NULL on error.
 */
static const uint8_t *hre_execute_op(const uint8_t **ip, size_t *code_size)
{
        bool dst_modified = false;
        uint32_t ins;
        uint8_t opcode;
        uint8_t src_spec;
        uint8_t dst_spec;
        uint16_t data_size;
        struct h_reg *src_reg, *dst_reg;
        uint8_t buf[20];
        const uint8_t *src_buf, *data;
        uint8_t *ptr;
        int i;
        void * (*bin_func)(void *, const void *, size_t);

        if (*code_size < 4)
                return NULL;

        ins = get_unaligned_be32(*ip);
        opcode = **ip;
        data = *ip + 4;
        src_spec = (ins >> 18) & 0x3f;
        dst_spec = (ins >> 12) & 0x3f;
        data_size = (ins & 0x7ff);

        debug("HRE: ins=%08x (op=%02x, s=%02x, d=%02x, L=%d)\n", ins,
              opcode, src_spec, dst_spec, data_size);

        if ((opcode & 0x80) && (data_size + 4) > *code_size)
                return NULL;

        src_reg = access_hreg(src_spec, HREG_RD);
        if (hre_err || hre_tpm_err)
                return NULL;
        dst_reg = access_hreg(dst_spec, (opcode & 0x40) ? HREG_RDWR : HREG_WR);
        if (hre_err || hre_tpm_err)
                return NULL;

        switch (opcode) {
        case HRE_NOP:
                goto end;
        case HRE_CHECK0:
                if (src_reg) {
                        for (i = 0; i < 20; ++i) {
                                if (src_reg->digest[i])
                                        return NULL;
                        }
                }
                break;
        case HRE_LOAD:
                bin_func = memcpy;
                goto do_bin_func;
        case HRE_XOR:
                bin_func = compute_xor;
                goto do_bin_func;
        case HRE_AND:
                bin_func = compute_and;
                goto do_bin_func;
        case HRE_OR:
                bin_func = compute_or;
                goto do_bin_func;
        case HRE_EXTEND:
                bin_func = compute_extend;
do_bin_func:
                if (!dst_reg)
                        return NULL;
                if (src_reg) {
                        src_buf = src_reg->digest;
                } else {
                        if (!data_size) {
                                memset(buf, 0, 20);
                                src_buf = buf;
                        } else if (data_size == 1) {
                                memset(buf, *data, 20);
                                src_buf = buf;
                        } else if (data_size >= 20) {
                                src_buf = data;
                        } else {
                                src_buf = buf;
                                for (ptr = (uint8_t *)src_buf, i = 20; i > 0;
                                        i -= data_size, ptr += data_size)
                                        memcpy(ptr, data,
                                               min_t(size_t, i, data_size));
                        }
                }
                bin_func(dst_reg->digest, src_buf, 20);
                dst_reg->valid = true;
                dst_modified = true;
                break;
        case HRE_LOADKEY:
                if (hre_op_loadkey(src_reg, dst_reg, data, data_size))
                        return NULL;
                break;
        default:
                return NULL;
        }

        if (dst_reg && dst_modified && IS_PCR_HREG(dst_spec)) {
                hre_tpm_err = tpm_extend(HREG_IDX(dst_spec), dst_reg->digest,
                        dst_reg->digest);
                if (hre_tpm_err) {
                        hre_err = HRE_E_TPM_FAILURE;
                        return NULL;
                }
        }
end:
        *ip += 4;
        *code_size -= 4;
        if (opcode & 0x80) {
                *ip += data_size;
                *code_size -= data_size;
        }

        return *ip;
}

/**
 * @brief runs a program on the hash register engine.
 * @param code          pointer to the (HRE) code.
 * @param code_size     size of the code (in bytes).
 * @return 0 on success, != 0 on failure.
 */
int hre_run_program(const uint8_t *code, size_t code_size)
{
        size_t code_left;
        const uint8_t *ip = code;

        code_left = code_size;
        hre_tpm_err = 0;
        hre_err = HRE_E_OK;
        while (code_left > 0)
                if (!hre_execute_op(&ip, &code_left))
                        return -1;

        return hre_err;
}

int hre_verify_program(struct key_program *prg)
{
        uint32_t crc;

        crc = crc32(0, prg->code, prg->code_size);

        if (crc != prg->code_crc) {
                printf("HRC crc mismatch: %08x != %08x\n",
                       crc, prg->code_crc);
                return 1;
        }
        return 0;
}