root/lib/libfido2/src/credman.c 
/*
 * Copyright (c) 2019-2021 Yubico AB. All rights reserved.
 * Use of this source code is governed by a BSD-style
 * license that can be found in the LICENSE file.
 */

#include <openssl/sha.h>

#include "fido.h"
#include "fido/credman.h"
#include "fido/es256.h"

#define CMD_CRED_METADATA       0x01
#define CMD_RP_BEGIN            0x02
#define CMD_RP_NEXT             0x03
#define CMD_RK_BEGIN            0x04
#define CMD_RK_NEXT             0x05
#define CMD_DELETE_CRED         0x06
#define CMD_UPDATE_CRED         0x07

static int
credman_grow_array(void **ptr, size_t *n_alloc, size_t *n_rx, size_t n,
    size_t size)
{
        void *new_ptr;

#ifdef FIDO_FUZZ
        if (n > UINT8_MAX) {
                fido_log_debug("%s: n > UINT8_MAX", __func__);
                return (-1);
        }
#endif

        if (n < *n_alloc)
                return (0);

        /* sanity check */
        if (*n_rx > 0 || *n_rx > *n_alloc || n < *n_alloc) {
                fido_log_debug("%s: n=%zu, n_rx=%zu, n_alloc=%zu", __func__, n,
                    *n_rx, *n_alloc);
                return (-1);
        }

        if ((new_ptr = recallocarray(*ptr, *n_alloc, n, size)) == NULL)
                return (-1);

        *ptr = new_ptr;
        *n_alloc = n;

        return (0);
}

static int
credman_prepare_hmac(uint8_t cmd, const void *body, cbor_item_t **param,
    fido_blob_t *hmac_data)
{
        cbor_item_t *param_cbor[3];
        const fido_cred_t *cred;
        size_t n;
        int ok = -1;

        memset(&param_cbor, 0, sizeof(param_cbor));

        if (body == NULL)
                return (fido_blob_set(hmac_data, &cmd, sizeof(cmd)));

        switch (cmd) {
        case CMD_RK_BEGIN:
                n = 1;
                if ((param_cbor[0] = fido_blob_encode(body)) == NULL) {
                        fido_log_debug("%s: cbor encode", __func__);
                        goto fail;
                }
                break;
        case CMD_DELETE_CRED:
                n = 2;
                if ((param_cbor[1] = cbor_encode_pubkey(body)) == NULL) {
                        fido_log_debug("%s: cbor encode", __func__);
                        goto fail;
                }
                break;
        case CMD_UPDATE_CRED:
                n = 3;
                cred = body;
                param_cbor[1] = cbor_encode_pubkey(&cred->attcred.id);
                param_cbor[2] = cbor_encode_user_entity(&cred->user);
                if (param_cbor[1] == NULL || param_cbor[2] == NULL) {
                        fido_log_debug("%s: cbor encode", __func__);
                        goto fail;
                }
                break;
        default:
                fido_log_debug("%s: unknown cmd=0x%02x", __func__, cmd);
                return (-1);
        }

        if ((*param = cbor_flatten_vector(param_cbor, n)) == NULL) {
                fido_log_debug("%s: cbor_flatten_vector", __func__);
                goto fail;
        }
        if (cbor_build_frame(cmd, param_cbor, n, hmac_data) < 0) {
                fido_log_debug("%s: cbor_build_frame", __func__);
                goto fail;
        }

        ok = 0;
fail:
        cbor_vector_free(param_cbor, nitems(param_cbor));

        return (ok);
}

static int
credman_tx(fido_dev_t *dev, uint8_t subcmd, const void *param, const char *pin,
    const char *rp_id, fido_opt_t uv, int *ms)
{
        fido_blob_t      f;
        fido_blob_t     *ecdh = NULL;
        fido_blob_t      hmac;
        es256_pk_t      *pk = NULL;
        cbor_item_t     *argv[4];
        const uint8_t    cmd = CTAP_CBOR_CRED_MGMT_PRE;
        int              r = FIDO_ERR_INTERNAL;

        memset(&f, 0, sizeof(f));
        memset(&hmac, 0, sizeof(hmac));
        memset(&argv, 0, sizeof(argv));

        if (fido_dev_is_fido2(dev) == false) {
                fido_log_debug("%s: fido_dev_is_fido2", __func__);
                r = FIDO_ERR_INVALID_COMMAND;
                goto fail;
        }

        /* subCommand */
        if ((argv[0] = cbor_build_uint8(subcmd)) == NULL) {
                fido_log_debug("%s: cbor encode", __func__);
                goto fail;
        }

        /* pinProtocol, pinAuth */
        if (pin != NULL || uv == FIDO_OPT_TRUE) {
                if (credman_prepare_hmac(subcmd, param, &argv[1], &hmac) < 0) {
                        fido_log_debug("%s: credman_prepare_hmac", __func__);
                        goto fail;
                }
                if ((r = fido_do_ecdh(dev, &pk, &ecdh, ms)) != FIDO_OK) {
                        fido_log_debug("%s: fido_do_ecdh", __func__);
                        goto fail;
                }
                if ((r = cbor_add_uv_params(dev, cmd, &hmac, pk, ecdh, pin,
                    rp_id, &argv[3], &argv[2], ms)) != FIDO_OK) {
                        fido_log_debug("%s: cbor_add_uv_params", __func__);
                        goto fail;
                }
        }

        /* framing and transmission */
        if (cbor_build_frame(cmd, argv, nitems(argv), &f) < 0 ||
            fido_tx(dev, CTAP_CMD_CBOR, f.ptr, f.len, ms) < 0) {
                fido_log_debug("%s: fido_tx", __func__);
                r = FIDO_ERR_TX;
                goto fail;
        }

        r = FIDO_OK;
fail:
        es256_pk_free(&pk);
        fido_blob_free(&ecdh);
        cbor_vector_free(argv, nitems(argv));
        free(f.ptr);
        free(hmac.ptr);

        return (r);
}

static int
credman_parse_metadata(const cbor_item_t *key, const cbor_item_t *val,
    void *arg)
{
        fido_credman_metadata_t *metadata = arg;

        if (cbor_isa_uint(key) == false ||
            cbor_int_get_width(key) != CBOR_INT_8) {
                fido_log_debug("%s: cbor type", __func__);
                return (0); /* ignore */
        }

        switch (cbor_get_uint8(key)) {
        case 1:
                return (cbor_decode_uint64(val, &metadata->rk_existing));
        case 2:
                return (cbor_decode_uint64(val, &metadata->rk_remaining));
        default:
                fido_log_debug("%s: cbor type", __func__);
                return (0); /* ignore */
        }
}

static int
credman_rx_metadata(fido_dev_t *dev, fido_credman_metadata_t *metadata, int *ms)
{
        unsigned char   reply[FIDO_MAXMSG];
        int             reply_len;
        int             r;

        memset(metadata, 0, sizeof(*metadata));

        if ((reply_len = fido_rx(dev, CTAP_CMD_CBOR, &reply, sizeof(reply),
            ms)) < 0) {
                fido_log_debug("%s: fido_rx", __func__);
                return (FIDO_ERR_RX);
        }

        if ((r = cbor_parse_reply(reply, (size_t)reply_len, metadata,
            credman_parse_metadata)) != FIDO_OK) {
                fido_log_debug("%s: credman_parse_metadata", __func__);
                return (r);
        }

        return (FIDO_OK);
}

static int
credman_get_metadata_wait(fido_dev_t *dev, fido_credman_metadata_t *metadata,
    const char *pin, int *ms)
{
        int r;

        if ((r = credman_tx(dev, CMD_CRED_METADATA, NULL, pin, NULL,
            FIDO_OPT_TRUE, ms)) != FIDO_OK ||
            (r = credman_rx_metadata(dev, metadata, ms)) != FIDO_OK)
                return (r);

        return (FIDO_OK);
}

int
fido_credman_get_dev_metadata(fido_dev_t *dev, fido_credman_metadata_t *metadata,
    const char *pin)
{
        int ms = dev->timeout_ms;

        return (credman_get_metadata_wait(dev, metadata, pin, &ms));
}

static int
credman_parse_rk(const cbor_item_t *key, const cbor_item_t *val, void *arg)
{
        fido_cred_t     *cred = arg;
        uint64_t         prot;

        if (cbor_isa_uint(key) == false ||
            cbor_int_get_width(key) != CBOR_INT_8) {
                fido_log_debug("%s: cbor type", __func__);
                return (0); /* ignore */
        }

        switch (cbor_get_uint8(key)) {
        case 6:
                return (cbor_decode_user(val, &cred->user));
        case 7:
                return (cbor_decode_cred_id(val, &cred->attcred.id));
        case 8:
                if (cbor_decode_pubkey(val, &cred->attcred.type,
                    &cred->attcred.pubkey) < 0)
                        return (-1);
                cred->type = cred->attcred.type; /* XXX */
                return (0);
        case 10:
                if (cbor_decode_uint64(val, &prot) < 0 || prot > INT_MAX ||
                    fido_cred_set_prot(cred, (int)prot) != FIDO_OK)
                        return (-1);
                return (0);
        case 11:
                return (fido_blob_decode(val, &cred->largeblob_key));
        default:
                fido_log_debug("%s: cbor type", __func__);
                return (0); /* ignore */
        }
}

static void
credman_reset_rk(fido_credman_rk_t *rk)
{
        for (size_t i = 0; i < rk->n_alloc; i++) {
                fido_cred_reset_tx(&rk->ptr[i]);
                fido_cred_reset_rx(&rk->ptr[i]);
        }

        free(rk->ptr);
        rk->ptr = NULL;
        memset(rk, 0, sizeof(*rk));
}

static int
credman_parse_rk_count(const cbor_item_t *key, const cbor_item_t *val,
    void *arg)
{
        fido_credman_rk_t *rk = arg;
        uint64_t n;

        /* totalCredentials */
        if (cbor_isa_uint(key) == false ||
            cbor_int_get_width(key) != CBOR_INT_8 ||
            cbor_get_uint8(key) != 9) {
                fido_log_debug("%s: cbor_type", __func__);
                return (0); /* ignore */
        }

        if (cbor_decode_uint64(val, &n) < 0 || n > SIZE_MAX) {
                fido_log_debug("%s: cbor_decode_uint64", __func__);
                return (-1);
        }

        if (credman_grow_array((void **)&rk->ptr, &rk->n_alloc, &rk->n_rx,
            (size_t)n, sizeof(*rk->ptr)) < 0) {
                fido_log_debug("%s: credman_grow_array", __func__);
                return (-1);
        }

        return (0);
}

static int
credman_rx_rk(fido_dev_t *dev, fido_credman_rk_t *rk, int *ms)
{
        unsigned char   reply[FIDO_MAXMSG];
        int             reply_len;
        int             r;

        credman_reset_rk(rk);

        if ((reply_len = fido_rx(dev, CTAP_CMD_CBOR, &reply, sizeof(reply),
            ms)) < 0) {
                fido_log_debug("%s: fido_rx", __func__);
                return (FIDO_ERR_RX);
        }

        /* adjust as needed */
        if ((r = cbor_parse_reply(reply, (size_t)reply_len, rk,
            credman_parse_rk_count)) != FIDO_OK) {
                fido_log_debug("%s: credman_parse_rk_count", __func__);
                return (r);
        }

        if (rk->n_alloc == 0) {
                fido_log_debug("%s: n_alloc=0", __func__);
                return (FIDO_OK);
        }

        /* parse the first rk */
        if ((r = cbor_parse_reply(reply, (size_t)reply_len, &rk->ptr[0],
            credman_parse_rk)) != FIDO_OK) {
                fido_log_debug("%s: credman_parse_rk", __func__);
                return (r);
        }

        rk->n_rx++;

        return (FIDO_OK);
}

static int
credman_rx_next_rk(fido_dev_t *dev, fido_credman_rk_t *rk, int *ms)
{
        unsigned char   reply[FIDO_MAXMSG];
        int             reply_len;
        int             r;

        if ((reply_len = fido_rx(dev, CTAP_CMD_CBOR, &reply, sizeof(reply),
            ms)) < 0) {
                fido_log_debug("%s: fido_rx", __func__);
                return (FIDO_ERR_RX);
        }

        /* sanity check */
        if (rk->n_rx >= rk->n_alloc) {
                fido_log_debug("%s: n_rx=%zu, n_alloc=%zu", __func__, rk->n_rx,
                    rk->n_alloc);
                return (FIDO_ERR_INTERNAL);
        }

        if ((r = cbor_parse_reply(reply, (size_t)reply_len, &rk->ptr[rk->n_rx],
            credman_parse_rk)) != FIDO_OK) {
                fido_log_debug("%s: credman_parse_rk", __func__);
                return (r);
        }

        return (FIDO_OK);
}

static int
credman_get_rk_wait(fido_dev_t *dev, const char *rp_id, fido_credman_rk_t *rk,
    const char *pin, int *ms)
{
        fido_blob_t     rp_dgst;
        uint8_t         dgst[SHA256_DIGEST_LENGTH];
        int             r;

        if (SHA256((const unsigned char *)rp_id, strlen(rp_id), dgst) != dgst) {
                fido_log_debug("%s: sha256", __func__);
                return (FIDO_ERR_INTERNAL);
        }

        rp_dgst.ptr = dgst;
        rp_dgst.len = sizeof(dgst);

        if ((r = credman_tx(dev, CMD_RK_BEGIN, &rp_dgst, pin, rp_id,
            FIDO_OPT_TRUE, ms)) != FIDO_OK ||
            (r = credman_rx_rk(dev, rk, ms)) != FIDO_OK)
                return (r);

        while (rk->n_rx < rk->n_alloc) {
                if ((r = credman_tx(dev, CMD_RK_NEXT, NULL, NULL, NULL,
                    FIDO_OPT_FALSE, ms)) != FIDO_OK ||
                    (r = credman_rx_next_rk(dev, rk, ms)) != FIDO_OK)
                        return (r);
                rk->n_rx++;
        }

        return (FIDO_OK);
}

int
fido_credman_get_dev_rk(fido_dev_t *dev, const char *rp_id,
    fido_credman_rk_t *rk, const char *pin)
{
        int ms = dev->timeout_ms;

        return (credman_get_rk_wait(dev, rp_id, rk, pin, &ms));
}

static int
credman_del_rk_wait(fido_dev_t *dev, const unsigned char *cred_id,
    size_t cred_id_len, const char *pin, int *ms)
{
        fido_blob_t cred;
        int r;

        memset(&cred, 0, sizeof(cred));

        if (fido_blob_set(&cred, cred_id, cred_id_len) < 0)
                return (FIDO_ERR_INVALID_ARGUMENT);

        if ((r = credman_tx(dev, CMD_DELETE_CRED, &cred, pin, NULL,
            FIDO_OPT_TRUE, ms)) != FIDO_OK ||
            (r = fido_rx_cbor_status(dev, ms)) != FIDO_OK)
                goto fail;

        r = FIDO_OK;
fail:
        free(cred.ptr);

        return (r);
}

int
fido_credman_del_dev_rk(fido_dev_t *dev, const unsigned char *cred_id,
    size_t cred_id_len, const char *pin)
{
        int ms = dev->timeout_ms;

        return (credman_del_rk_wait(dev, cred_id, cred_id_len, pin, &ms));
}

static int
credman_parse_rp(const cbor_item_t *key, const cbor_item_t *val, void *arg)
{
        struct fido_credman_single_rp *rp = arg;

        if (cbor_isa_uint(key) == false ||
            cbor_int_get_width(key) != CBOR_INT_8) {
                fido_log_debug("%s: cbor type", __func__);
                return (0); /* ignore */
        }

        switch (cbor_get_uint8(key)) {
        case 3:
                return (cbor_decode_rp_entity(val, &rp->rp_entity));
        case 4:
                return (fido_blob_decode(val, &rp->rp_id_hash));
        default:
                fido_log_debug("%s: cbor type", __func__);
                return (0); /* ignore */
        }
}

static void
credman_reset_rp(fido_credman_rp_t *rp)
{
        for (size_t i = 0; i < rp->n_alloc; i++) {
                free(rp->ptr[i].rp_entity.id);
                free(rp->ptr[i].rp_entity.name);
                rp->ptr[i].rp_entity.id = NULL;
                rp->ptr[i].rp_entity.name = NULL;
                fido_blob_reset(&rp->ptr[i].rp_id_hash);
        }

        free(rp->ptr);
        rp->ptr = NULL;
        memset(rp, 0, sizeof(*rp));
}

static int
credman_parse_rp_count(const cbor_item_t *key, const cbor_item_t *val,
    void *arg)
{
        fido_credman_rp_t *rp = arg;
        uint64_t n;

        /* totalRPs */
        if (cbor_isa_uint(key) == false ||
            cbor_int_get_width(key) != CBOR_INT_8 ||
            cbor_get_uint8(key) != 5) {
                fido_log_debug("%s: cbor_type", __func__);
                return (0); /* ignore */
        }

        if (cbor_decode_uint64(val, &n) < 0 || n > SIZE_MAX) {
                fido_log_debug("%s: cbor_decode_uint64", __func__);
                return (-1);
        }

        if (credman_grow_array((void **)&rp->ptr, &rp->n_alloc, &rp->n_rx,
            (size_t)n, sizeof(*rp->ptr)) < 0) {
                fido_log_debug("%s: credman_grow_array", __func__);
                return (-1);
        }

        return (0);
}

static int
credman_rx_rp(fido_dev_t *dev, fido_credman_rp_t *rp, int *ms)
{
        unsigned char   reply[FIDO_MAXMSG];
        int             reply_len;
        int             r;

        credman_reset_rp(rp);

        if ((reply_len = fido_rx(dev, CTAP_CMD_CBOR, &reply, sizeof(reply),
            ms)) < 0) {
                fido_log_debug("%s: fido_rx", __func__);
                return (FIDO_ERR_RX);
        }

        /* adjust as needed */
        if ((r = cbor_parse_reply(reply, (size_t)reply_len, rp,
            credman_parse_rp_count)) != FIDO_OK) {
                fido_log_debug("%s: credman_parse_rp_count", __func__);
                return (r);
        }

        if (rp->n_alloc == 0) {
                fido_log_debug("%s: n_alloc=0", __func__);
                return (FIDO_OK);
        }

        /* parse the first rp */
        if ((r = cbor_parse_reply(reply, (size_t)reply_len, &rp->ptr[0],
            credman_parse_rp)) != FIDO_OK) {
                fido_log_debug("%s: credman_parse_rp", __func__);
                return (r);
        }

        rp->n_rx++;

        return (FIDO_OK);
}

static int
credman_rx_next_rp(fido_dev_t *dev, fido_credman_rp_t *rp, int *ms)
{
        unsigned char   reply[FIDO_MAXMSG];
        int             reply_len;
        int             r;

        if ((reply_len = fido_rx(dev, CTAP_CMD_CBOR, &reply, sizeof(reply),
            ms)) < 0) {
                fido_log_debug("%s: fido_rx", __func__);
                return (FIDO_ERR_RX);
        }

        /* sanity check */
        if (rp->n_rx >= rp->n_alloc) {
                fido_log_debug("%s: n_rx=%zu, n_alloc=%zu", __func__, rp->n_rx,
                    rp->n_alloc);
                return (FIDO_ERR_INTERNAL);
        }

        if ((r = cbor_parse_reply(reply, (size_t)reply_len, &rp->ptr[rp->n_rx],
            credman_parse_rp)) != FIDO_OK) {
                fido_log_debug("%s: credman_parse_rp", __func__);
                return (r);
        }

        return (FIDO_OK);
}

static int
credman_get_rp_wait(fido_dev_t *dev, fido_credman_rp_t *rp, const char *pin,
    int *ms)
{
        int r;

        if ((r = credman_tx(dev, CMD_RP_BEGIN, NULL, pin, NULL,
            FIDO_OPT_TRUE, ms)) != FIDO_OK ||
            (r = credman_rx_rp(dev, rp, ms)) != FIDO_OK)
                return (r);

        while (rp->n_rx < rp->n_alloc) {
                if ((r = credman_tx(dev, CMD_RP_NEXT, NULL, NULL, NULL,
                    FIDO_OPT_FALSE, ms)) != FIDO_OK ||
                    (r = credman_rx_next_rp(dev, rp, ms)) != FIDO_OK)
                        return (r);
                rp->n_rx++;
        }

        return (FIDO_OK);
}

int
fido_credman_get_dev_rp(fido_dev_t *dev, fido_credman_rp_t *rp, const char *pin)
{
        int ms = dev->timeout_ms;

        return (credman_get_rp_wait(dev, rp, pin, &ms));
}

static int
credman_set_dev_rk_wait(fido_dev_t *dev, fido_cred_t *cred, const char *pin,
    int *ms)
{
        int r;

        if ((r = credman_tx(dev, CMD_UPDATE_CRED, cred, pin, NULL,
            FIDO_OPT_TRUE, ms)) != FIDO_OK ||
            (r = fido_rx_cbor_status(dev, ms)) != FIDO_OK)
                return (r);

        return (FIDO_OK);
}

int
fido_credman_set_dev_rk(fido_dev_t *dev, fido_cred_t *cred, const char *pin)
{
        int ms = dev->timeout_ms;

        return (credman_set_dev_rk_wait(dev, cred, pin, &ms));
}

fido_credman_rk_t *
fido_credman_rk_new(void)
{
        return (calloc(1, sizeof(fido_credman_rk_t)));
}

void
fido_credman_rk_free(fido_credman_rk_t **rk_p)
{
        fido_credman_rk_t *rk;

        if (rk_p == NULL || (rk = *rk_p) == NULL)
                return;

        credman_reset_rk(rk);
        free(rk);
        *rk_p = NULL;
}

size_t
fido_credman_rk_count(const fido_credman_rk_t *rk)
{
        return (rk->n_rx);
}

const fido_cred_t *
fido_credman_rk(const fido_credman_rk_t *rk, size_t idx)
{
        if (idx >= rk->n_alloc)
                return (NULL);

        return (&rk->ptr[idx]);
}

fido_credman_metadata_t *
fido_credman_metadata_new(void)
{
        return (calloc(1, sizeof(fido_credman_metadata_t)));
}

void
fido_credman_metadata_free(fido_credman_metadata_t **metadata_p)
{
        fido_credman_metadata_t *metadata;

        if (metadata_p == NULL || (metadata = *metadata_p) == NULL)
                return;

        free(metadata);
        *metadata_p = NULL;
}

uint64_t
fido_credman_rk_existing(const fido_credman_metadata_t *metadata)
{
        return (metadata->rk_existing);
}

uint64_t
fido_credman_rk_remaining(const fido_credman_metadata_t *metadata)
{
        return (metadata->rk_remaining);
}

fido_credman_rp_t *
fido_credman_rp_new(void)
{
        return (calloc(1, sizeof(fido_credman_rp_t)));
}

void
fido_credman_rp_free(fido_credman_rp_t **rp_p)
{
        fido_credman_rp_t *rp;

        if (rp_p == NULL || (rp = *rp_p) == NULL)
                return;

        credman_reset_rp(rp);
        free(rp);
        *rp_p = NULL;
}

size_t
fido_credman_rp_count(const fido_credman_rp_t *rp)
{
        return (rp->n_rx);
}

const char *
fido_credman_rp_id(const fido_credman_rp_t *rp, size_t idx)
{
        if (idx >= rp->n_alloc)
                return (NULL);

        return (rp->ptr[idx].rp_entity.id);
}

const char *
fido_credman_rp_name(const fido_credman_rp_t *rp, size_t idx)
{
        if (idx >= rp->n_alloc)
                return (NULL);

        return (rp->ptr[idx].rp_entity.name);
}

size_t
fido_credman_rp_id_hash_len(const fido_credman_rp_t *rp, size_t idx)
{
        if (idx >= rp->n_alloc)
                return (0);

        return (rp->ptr[idx].rp_id_hash.len);
}

const unsigned char *
fido_credman_rp_id_hash_ptr(const fido_credman_rp_t *rp, size_t idx)
{
        if (idx >= rp->n_alloc)
                return (NULL);

        return (rp->ptr[idx].rp_id_hash.ptr);
}