trusted.c

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/*
 * Copyright (C) 2010 IBM Corporation
 *
 * Author:
 * David Safford <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 2 of the License.
 *
 * See Documentation/security/keys-trusted-encrypted.txt
 */

#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/parser.h>
#include <linux/string.h>
#include <linux/err.h>
#include <keys/user-type.h>
#include <keys/trusted-type.h>
#include <linux/key-type.h>
#include <linux/rcupdate.h>
#include <linux/crypto.h>
#include <crypto/hash.h>
#include <crypto/sha.h>
#include <linux/capability.h>
#include <linux/tpm.h>
#include <linux/tpm_command.h>

#include "trusted.h"

static const char hmac_alg[] = "hmac(sha1)";
static const char hash_alg[] = "sha1";

struct sdesc {
    struct shash_desc shash;
    char ctx[];
};

static struct crypto_shash *hashalg;
static struct crypto_shash *hmacalg;

static struct sdesc *init_sdesc(struct crypto_shash *alg)
{
    struct sdesc *sdesc;
    int size;

    size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
    sdesc = kmalloc(size, GFP_KERNEL);
    if (!sdesc)
        return ERR_PTR(-ENOMEM);
    sdesc->shash.tfm = alg;
    sdesc->shash.flags = 0x0;
    return sdesc;
}

static int TSS_sha1(const unsigned char *data, unsigned int datalen,
            unsigned char *digest)
{
    struct sdesc *sdesc;
    int ret;

    sdesc = init_sdesc(hashalg);
    if (IS_ERR(sdesc)) {
        pr_info("trusted_key: can't alloc %s\n", hash_alg);
        return PTR_ERR(sdesc);
    }

    ret = crypto_shash_digest(&sdesc->shash, data, datalen, digest);
    kfree(sdesc);
    return ret;
}

static int TSS_rawhmac(unsigned char *digest, const unsigned char *key,
               unsigned int keylen, ...)
{
    struct sdesc *sdesc;
    va_list argp;
    unsigned int dlen;
    unsigned char *data;
    int ret;

    sdesc = init_sdesc(hmacalg);
    if (IS_ERR(sdesc)) {
        pr_info("trusted_key: can't alloc %s\n", hmac_alg);
        return PTR_ERR(sdesc);
    }

    ret = crypto_shash_setkey(hmacalg, key, keylen);
    if (ret < 0)
        goto out;
    ret = crypto_shash_init(&sdesc->shash);
    if (ret < 0)
        goto out;

    va_start(argp, keylen);
    for (;;) {
        dlen = va_arg(argp, unsigned int);
        if (dlen == 0)
            break;
        data = va_arg(argp, unsigned char *);
        if (data == NULL) {
            ret = -EINVAL;
            break;
        }
        ret = crypto_shash_update(&sdesc->shash, data, dlen);
        if (ret < 0)
            break;
    }
    va_end(argp);
    if (!ret)
        ret = crypto_shash_final(&sdesc->shash, digest);
out:
    kfree(sdesc);
    return ret;
}

/*
 * calculate authorization info fields to send to TPM
 */
static int TSS_authhmac(unsigned char *digest, const unsigned char *key,
            unsigned int keylen, unsigned char *h1,
            unsigned char *h2, unsigned char h3, ...)
{
    unsigned char paramdigest[SHA1_DIGEST_SIZE];
    struct sdesc *sdesc;
    unsigned int dlen;
    unsigned char *data;
    unsigned char c;
    int ret;
    va_list argp;

    sdesc = init_sdesc(hashalg);
    if (IS_ERR(sdesc)) {
        pr_info("trusted_key: can't alloc %s\n", hash_alg);
        return PTR_ERR(sdesc);
    }

    c = h3;
    ret = crypto_shash_init(&sdesc->shash);
    if (ret < 0)
        goto out;
    va_start(argp, h3);
    for (;;) {
        dlen = va_arg(argp, unsigned int);
        if (dlen == 0)
            break;
        data = va_arg(argp, unsigned char *);
        if (!data) {
            ret = -EINVAL;
            break;
        }
        ret = crypto_shash_update(&sdesc->shash, data, dlen);
        if (ret < 0)
            break;
    }
    va_end(argp);
    if (!ret)
        ret = crypto_shash_final(&sdesc->shash, paramdigest);
    if (!ret)
        ret = TSS_rawhmac(digest, key, keylen, SHA1_DIGEST_SIZE,
                  paramdigest, TPM_NONCE_SIZE, h1,
                  TPM_NONCE_SIZE, h2, 1, &c, 0, 0);
out:
    kfree(sdesc);
    return ret;
}

/*
 * verify the AUTH1_COMMAND (Seal) result from TPM
 */
static int TSS_checkhmac1(unsigned char *buffer,
              const uint32_t command,
              const unsigned char *ononce,
              const unsigned char *key,
              unsigned int keylen, ...)
{
    uint32_t bufsize;
    uint16_t tag;
    uint32_t ordinal;
    uint32_t result;
    unsigned char *enonce;
    unsigned char *continueflag;
    unsigned char *authdata;
    unsigned char testhmac[SHA1_DIGEST_SIZE];
    unsigned char paramdigest[SHA1_DIGEST_SIZE];
    struct sdesc *sdesc;
    unsigned int dlen;
    unsigned int dpos;
    va_list argp;
    int ret;

    bufsize = LOAD32(buffer, TPM_SIZE_OFFSET);
    tag = LOAD16(buffer, 0);
    ordinal = command;
    result = LOAD32N(buffer, TPM_RETURN_OFFSET);
    if (tag == TPM_TAG_RSP_COMMAND)
        return 0;
    if (tag != TPM_TAG_RSP_AUTH1_COMMAND)
        return -EINVAL;
    authdata = buffer + bufsize - SHA1_DIGEST_SIZE;
    continueflag = authdata - 1;
    enonce = continueflag - TPM_NONCE_SIZE;

    sdesc = init_sdesc(hashalg);
    if (IS_ERR(sdesc)) {
        pr_info("trusted_key: can't alloc %s\n", hash_alg);
        return PTR_ERR(sdesc);
    }
    ret = crypto_shash_init(&sdesc->shash);
    if (ret < 0)
        goto out;
    ret = crypto_shash_update(&sdesc->shash, (const u8 *)&result,
                  sizeof result);
    if (ret < 0)
        goto out;
    ret = crypto_shash_update(&sdesc->shash, (const u8 *)&ordinal,
                  sizeof ordinal);
    if (ret < 0)
        goto out;
    va_start(argp, keylen);
    for (;;) {
        dlen = va_arg(argp, unsigned int);
        if (dlen == 0)
            break;
        dpos = va_arg(argp, unsigned int);
        ret = crypto_shash_update(&sdesc->shash, buffer + dpos, dlen);
        if (ret < 0)
            break;
    }
    va_end(argp);
    if (!ret)
        ret = crypto_shash_final(&sdesc->shash, paramdigest);
    if (ret < 0)
        goto out;

    ret = TSS_rawhmac(testhmac, key, keylen, SHA1_DIGEST_SIZE, paramdigest,
              TPM_NONCE_SIZE, enonce, TPM_NONCE_SIZE, ononce,
              1, continueflag, 0, 0);
    if (ret < 0)
        goto out;

    if (memcmp(testhmac, authdata, SHA1_DIGEST_SIZE))
        ret = -EINVAL;
out:
    kfree(sdesc);
    return ret;
}

/*
 * verify the AUTH2_COMMAND (unseal) result from TPM
 */
static int TSS_checkhmac2(unsigned char *buffer,
              const uint32_t command,
              const unsigned char *ononce,
              const unsigned char *key1,
              unsigned int keylen1,
              const unsigned char *key2,
              unsigned int keylen2, ...)
{
    uint32_t bufsize;
    uint16_t tag;
    uint32_t ordinal;
    uint32_t result;
    unsigned char *enonce1;
    unsigned char *continueflag1;
    unsigned char *authdata1;
    unsigned char *enonce2;
    unsigned char *continueflag2;
    unsigned char *authdata2;
    unsigned char testhmac1[SHA1_DIGEST_SIZE];
    unsigned char testhmac2[SHA1_DIGEST_SIZE];
    unsigned char paramdigest[SHA1_DIGEST_SIZE];
    struct sdesc *sdesc;
    unsigned int dlen;
    unsigned int dpos;
    va_list argp;
    int ret;

    bufsize = LOAD32(buffer, TPM_SIZE_OFFSET);
    tag = LOAD16(buffer, 0);
    ordinal = command;
    result = LOAD32N(buffer, TPM_RETURN_OFFSET);

    if (tag == TPM_TAG_RSP_COMMAND)
        return 0;
    if (tag != TPM_TAG_RSP_AUTH2_COMMAND)
        return -EINVAL;
    authdata1 = buffer + bufsize - (SHA1_DIGEST_SIZE + 1
            + SHA1_DIGEST_SIZE + SHA1_DIGEST_SIZE);
    authdata2 = buffer + bufsize - (SHA1_DIGEST_SIZE);
    continueflag1 = authdata1 - 1;
    continueflag2 = authdata2 - 1;
    enonce1 = continueflag1 - TPM_NONCE_SIZE;
    enonce2 = continueflag2 - TPM_NONCE_SIZE;

    sdesc = init_sdesc(hashalg);
    if (IS_ERR(sdesc)) {
        pr_info("trusted_key: can't alloc %s\n", hash_alg);
        return PTR_ERR(sdesc);
    }
    ret = crypto_shash_init(&sdesc->shash);
    if (ret < 0)
        goto out;
    ret = crypto_shash_update(&sdesc->shash, (const u8 *)&result,
                  sizeof result);
    if (ret < 0)
        goto out;
    ret = crypto_shash_update(&sdesc->shash, (const u8 *)&ordinal,
                  sizeof ordinal);
    if (ret < 0)
        goto out;

    va_start(argp, keylen2);
    for (;;) {
        dlen = va_arg(argp, unsigned int);
        if (dlen == 0)
            break;
        dpos = va_arg(argp, unsigned int);
        ret = crypto_shash_update(&sdesc->shash, buffer + dpos, dlen);
        if (ret < 0)
            break;
    }
    va_end(argp);
    if (!ret)
        ret = crypto_shash_final(&sdesc->shash, paramdigest);
    if (ret < 0)
        goto out;

    ret = TSS_rawhmac(testhmac1, key1, keylen1, SHA1_DIGEST_SIZE,
              paramdigest, TPM_NONCE_SIZE, enonce1,
              TPM_NONCE_SIZE, ononce, 1, continueflag1, 0, 0);
    if (ret < 0)
        goto out;
    if (memcmp(testhmac1, authdata1, SHA1_DIGEST_SIZE)) {
        ret = -EINVAL;
        goto out;
    }
    ret = TSS_rawhmac(testhmac2, key2, keylen2, SHA1_DIGEST_SIZE,
              paramdigest, TPM_NONCE_SIZE, enonce2,
              TPM_NONCE_SIZE, ononce, 1, continueflag2, 0, 0);
    if (ret < 0)
        goto out;
    if (memcmp(testhmac2, authdata2, SHA1_DIGEST_SIZE))
        ret = -EINVAL;
out:
    kfree(sdesc);
    return ret;
}

/*
 * For key specific tpm requests, we will generate and send our
 * own TPM command packets using the drivers send function.
 */
static int trusted_tpm_send(const u32 chip_num, unsigned char *cmd,
                size_t buflen)
{
    int rc;

    dump_tpm_buf(cmd);
    rc = tpm_send(chip_num, cmd, buflen);
    dump_tpm_buf(cmd);
    if (rc > 0)
        /* Can't return positive return codes values to keyctl */
        rc = -EPERM;
    return rc;
}

/*
 * Lock a trusted key, by extending a selected PCR.
 *
 * Prevents a trusted key that is sealed to PCRs from being accessed.
 * This uses the tpm driver's extend function.
 */
static int pcrlock(const int pcrnum)
{
    unsigned char hash[SHA1_DIGEST_SIZE];
    int ret;

    if (!capable(CAP_SYS_ADMIN))
        return -EPERM;
    ret = tpm_get_random(TPM_ANY_NUM, hash, SHA1_DIGEST_SIZE);
    if (ret != SHA1_DIGEST_SIZE)
        return ret;
    return tpm_pcr_extend(TPM_ANY_NUM, pcrnum, hash) ? -EINVAL : 0;
}

/*
 * Create an object specific authorisation protocol (OSAP) session
 */
static int osap(struct tpm_buf *tb, struct osapsess *s,
        const unsigned char *key, uint16_t type, uint32_t handle)
{
    unsigned char enonce[TPM_NONCE_SIZE];
    unsigned char ononce[TPM_NONCE_SIZE];
    int ret;

    ret = tpm_get_random(TPM_ANY_NUM, ononce, TPM_NONCE_SIZE);
    if (ret != TPM_NONCE_SIZE)
        return ret;

    INIT_BUF(tb);
    store16(tb, TPM_TAG_RQU_COMMAND);
    store32(tb, TPM_OSAP_SIZE);
    store32(tb, TPM_ORD_OSAP);
    store16(tb, type);
    store32(tb, handle);
    storebytes(tb, ononce, TPM_NONCE_SIZE);

    ret = trusted_tpm_send(TPM_ANY_NUM, tb->data, MAX_BUF_SIZE);
    if (ret < 0)
        return ret;

    s->handle = LOAD32(tb->data, TPM_DATA_OFFSET);
    memcpy(s->enonce, &(tb->data[TPM_DATA_OFFSET + sizeof(uint32_t)]),
           TPM_NONCE_SIZE);
    memcpy(enonce, &(tb->data[TPM_DATA_OFFSET + sizeof(uint32_t) +
                  TPM_NONCE_SIZE]), TPM_NONCE_SIZE);
    return TSS_rawhmac(s->secret, key, SHA1_DIGEST_SIZE, TPM_NONCE_SIZE,
               enonce, TPM_NONCE_SIZE, ononce, 0, 0);
}

/*
 * Create an object independent authorisation protocol (oiap) session
 */
static int oiap(struct tpm_buf *tb, uint32_t *handle, unsigned char *nonce)
{
    int ret;

    INIT_BUF(tb);
    store16(tb, TPM_TAG_RQU_COMMAND);
    store32(tb, TPM_OIAP_SIZE);
    store32(tb, TPM_ORD_OIAP);
    ret = trusted_tpm_send(TPM_ANY_NUM, tb->data, MAX_BUF_SIZE);
    if (ret < 0)
        return ret;

    *handle = LOAD32(tb->data, TPM_DATA_OFFSET);
    memcpy(nonce, &tb->data[TPM_DATA_OFFSET + sizeof(uint32_t)],
           TPM_NONCE_SIZE);
    return 0;
}

struct tpm_digests {
    unsigned char encauth[SHA1_DIGEST_SIZE];
    unsigned char pubauth[SHA1_DIGEST_SIZE];
    unsigned char xorwork[SHA1_DIGEST_SIZE * 2];
    unsigned char xorhash[SHA1_DIGEST_SIZE];
    unsigned char nonceodd[TPM_NONCE_SIZE];
};

/*
 * Have the TPM seal(encrypt) the trusted key, possibly based on
 * Platform Configuration Registers (PCRs). AUTH1 for sealing key.
 */
static int tpm_seal(struct tpm_buf *tb, uint16_t keytype,
            uint32_t keyhandle, const unsigned char *keyauth,
            const unsigned char *data, uint32_t datalen,
            unsigned char *blob, uint32_t *bloblen,
            const unsigned char *blobauth,
            const unsigned char *pcrinfo, uint32_t pcrinfosize)
{
    struct osapsess sess;
    struct tpm_digests *td;
    unsigned char cont;
    uint32_t ordinal;
    uint32_t pcrsize;
    uint32_t datsize;
    int sealinfosize;
    int encdatasize;
    int storedsize;
    int ret;
    int i;

    /* alloc some work space for all the hashes */
    td = kmalloc(sizeof *td, GFP_KERNEL);
    if (!td)
        return -ENOMEM;

    /* get session for sealing key */
    ret = osap(tb, &sess, keyauth, keytype, keyhandle);
    if (ret < 0)
        goto out;
    dump_sess(&sess);

    /* calculate encrypted authorization value */
    memcpy(td->xorwork, sess.secret, SHA1_DIGEST_SIZE);
    memcpy(td->xorwork + SHA1_DIGEST_SIZE, sess.enonce, SHA1_DIGEST_SIZE);
    ret = TSS_sha1(td->xorwork, SHA1_DIGEST_SIZE * 2, td->xorhash);
    if (ret < 0)
        goto out;

    ret = tpm_get_random(TPM_ANY_NUM, td->nonceodd, TPM_NONCE_SIZE);
    if (ret != TPM_NONCE_SIZE)
        goto out;
    ordinal = htonl(TPM_ORD_SEAL);
    datsize = htonl(datalen);
    pcrsize = htonl(pcrinfosize);
    cont = 0;

    /* encrypt data authorization key */
    for (i = 0; i < SHA1_DIGEST_SIZE; ++i)
        td->encauth[i] = td->xorhash[i] ^ blobauth[i];

    /* calculate authorization HMAC value */
    if (pcrinfosize == 0) {
        /* no pcr info specified */
        ret = TSS_authhmac(td->pubauth, sess.secret, SHA1_DIGEST_SIZE,
                   sess.enonce, td->nonceodd, cont,
                   sizeof(uint32_t), &ordinal, SHA1_DIGEST_SIZE,
                   td->encauth, sizeof(uint32_t), &pcrsize,
                   sizeof(uint32_t), &datsize, datalen, data, 0,
                   0);
    } else {
        /* pcr info specified */
        ret = TSS_authhmac(td->pubauth, sess.secret, SHA1_DIGEST_SIZE,
                   sess.enonce, td->nonceodd, cont,
                   sizeof(uint32_t), &ordinal, SHA1_DIGEST_SIZE,
                   td->encauth, sizeof(uint32_t), &pcrsize,
                   pcrinfosize, pcrinfo, sizeof(uint32_t),
                   &datsize, datalen, data, 0, 0);
    }
    if (ret < 0)
        goto out;

    /* build and send the TPM request packet */
    INIT_BUF(tb);
    store16(tb, TPM_TAG_RQU_AUTH1_COMMAND);
    store32(tb, TPM_SEAL_SIZE + pcrinfosize + datalen);
    store32(tb, TPM_ORD_SEAL);
    store32(tb, keyhandle);
    storebytes(tb, td->encauth, SHA1_DIGEST_SIZE);
    store32(tb, pcrinfosize);
    storebytes(tb, pcrinfo, pcrinfosize);
    store32(tb, datalen);
    storebytes(tb, data, datalen);
    store32(tb, sess.handle);
    storebytes(tb, td->nonceodd, TPM_NONCE_SIZE);
    store8(tb, cont);
    storebytes(tb, td->pubauth, SHA1_DIGEST_SIZE);

    ret = trusted_tpm_send(TPM_ANY_NUM, tb->data, MAX_BUF_SIZE);
    if (ret < 0)
        goto out;

    /* calculate the size of the returned Blob */
    sealinfosize = LOAD32(tb->data, TPM_DATA_OFFSET + sizeof(uint32_t));
    encdatasize = LOAD32(tb->data, TPM_DATA_OFFSET + sizeof(uint32_t) +
                 sizeof(uint32_t) + sealinfosize);
    storedsize = sizeof(uint32_t) + sizeof(uint32_t) + sealinfosize +
        sizeof(uint32_t) + encdatasize;

    /* check the HMAC in the response */
    ret = TSS_checkhmac1(tb->data, ordinal, td->nonceodd, sess.secret,
                 SHA1_DIGEST_SIZE, storedsize, TPM_DATA_OFFSET, 0,
                 0);

    /* copy the returned blob to caller */
    if (!ret) {
        memcpy(blob, tb->data + TPM_DATA_OFFSET, storedsize);
        *bloblen = storedsize;
    }
out:
    kfree(td);
    return ret;
}

/*
 * use the AUTH2_COMMAND form of unseal, to authorize both key and blob
 */
static int tpm_unseal(struct tpm_buf *tb,
              uint32_t keyhandle, const unsigned char *keyauth,
              const unsigned char *blob, int bloblen,
              const unsigned char *blobauth,
              unsigned char *data, unsigned int *datalen)
{
    unsigned char nonceodd[TPM_NONCE_SIZE];
    unsigned char enonce1[TPM_NONCE_SIZE];
    unsigned char enonce2[TPM_NONCE_SIZE];
    unsigned char authdata1[SHA1_DIGEST_SIZE];
    unsigned char authdata2[SHA1_DIGEST_SIZE];
    uint32_t authhandle1 = 0;
    uint32_t authhandle2 = 0;
    unsigned char cont = 0;
    uint32_t ordinal;
    uint32_t keyhndl;
    int ret;

    /* sessions for unsealing key and data */
    ret = oiap(tb, &authhandle1, enonce1);
    if (ret < 0) {
        pr_info("trusted_key: oiap failed (%d)\n", ret);
        return ret;
    }
    ret = oiap(tb, &authhandle2, enonce2);
    if (ret < 0) {
        pr_info("trusted_key: oiap failed (%d)\n", ret);
        return ret;
    }

    ordinal = htonl(TPM_ORD_UNSEAL);
    keyhndl = htonl(SRKHANDLE);
    ret = tpm_get_random(TPM_ANY_NUM, nonceodd, TPM_NONCE_SIZE);
    if (ret != TPM_NONCE_SIZE) {
        pr_info("trusted_key: tpm_get_random failed (%d)\n", ret);
        return ret;
    }
    ret = TSS_authhmac(authdata1, keyauth, TPM_NONCE_SIZE,
               enonce1, nonceodd, cont, sizeof(uint32_t),
               &ordinal, bloblen, blob, 0, 0);
    if (ret < 0)
        return ret;
    ret = TSS_authhmac(authdata2, blobauth, TPM_NONCE_SIZE,
               enonce2, nonceodd, cont, sizeof(uint32_t),
               &ordinal, bloblen, blob, 0, 0);
    if (ret < 0)
        return ret;

    /* build and send TPM request packet */
    INIT_BUF(tb);
    store16(tb, TPM_TAG_RQU_AUTH2_COMMAND);
    store32(tb, TPM_UNSEAL_SIZE + bloblen);
    store32(tb, TPM_ORD_UNSEAL);
    store32(tb, keyhandle);
    storebytes(tb, blob, bloblen);
    store32(tb, authhandle1);
    storebytes(tb, nonceodd, TPM_NONCE_SIZE);
    store8(tb, cont);
    storebytes(tb, authdata1, SHA1_DIGEST_SIZE);
    store32(tb, authhandle2);
    storebytes(tb, nonceodd, TPM_NONCE_SIZE);
    store8(tb, cont);
    storebytes(tb, authdata2, SHA1_DIGEST_SIZE);

    ret = trusted_tpm_send(TPM_ANY_NUM, tb->data, MAX_BUF_SIZE);
    if (ret < 0) {
        pr_info("trusted_key: authhmac failed (%d)\n", ret);
        return ret;
    }

    *datalen = LOAD32(tb->data, TPM_DATA_OFFSET);
    ret = TSS_checkhmac2(tb->data, ordinal, nonceodd,
                 keyauth, SHA1_DIGEST_SIZE,
                 blobauth, SHA1_DIGEST_SIZE,
                 sizeof(uint32_t), TPM_DATA_OFFSET,
                 *datalen, TPM_DATA_OFFSET + sizeof(uint32_t), 0,
                 0);
    if (ret < 0) {
        pr_info("trusted_key: TSS_checkhmac2 failed (%d)\n", ret);
        return ret;
    }
    memcpy(data, tb->data + TPM_DATA_OFFSET + sizeof(uint32_t), *datalen);
    return 0;
}

/*
 * Have the TPM seal(encrypt) the symmetric key
 */
static int key_seal(struct trusted_key_payload *p,
            struct trusted_key_options *o)
{
    struct tpm_buf *tb;
    int ret;

    tb = kzalloc(sizeof *tb, GFP_KERNEL);
    if (!tb)
        return -ENOMEM;

    /* include migratable flag at end of sealed key */
    p->key[p->key_len] = p->migratable;

    ret = tpm_seal(tb, o->keytype, o->keyhandle, o->keyauth,
               p->key, p->key_len + 1, p->blob, &p->blob_len,
               o->blobauth, o->pcrinfo, o->pcrinfo_len);
    if (ret < 0)
        pr_info("trusted_key: srkseal failed (%d)\n", ret);

    kfree(tb);
    return ret;
}

/*
 * Have the TPM unseal(decrypt) the symmetric key
 */
static int key_unseal(struct trusted_key_payload *p,
              struct trusted_key_options *o)
{
    struct tpm_buf *tb;
    int ret;

    tb = kzalloc(sizeof *tb, GFP_KERNEL);
    if (!tb)
        return -ENOMEM;

    ret = tpm_unseal(tb, o->keyhandle, o->keyauth, p->blob, p->blob_len,
             o->blobauth, p->key, &p->key_len);
    if (ret < 0)
        pr_info("trusted_key: srkunseal failed (%d)\n", ret);
    else
        /* pull migratable flag out of sealed key */
        p->migratable = p->key[--p->key_len];

    kfree(tb);
    return ret;
}

enum {
    Opt_err = -1,
    Opt_new, Opt_load, Opt_update,
    Opt_keyhandle, Opt_keyauth, Opt_blobauth,
    Opt_pcrinfo, Opt_pcrlock, Opt_migratable
};

static const match_table_t key_tokens = {
    {Opt_new, "new"},
    {Opt_load, "load"},
    {Opt_update, "update"},
    {Opt_keyhandle, "keyhandle=%s"},
    {Opt_keyauth, "keyauth=%s"},
    {Opt_blobauth, "blobauth=%s"},
    {Opt_pcrinfo, "pcrinfo=%s"},
    {Opt_pcrlock, "pcrlock=%s"},
    {Opt_migratable, "migratable=%s"},
    {Opt_err, NULL}
};

/* can have zero or more token= options */
static int getoptions(char *c, struct trusted_key_payload *pay,
              struct trusted_key_options *opt)
{
    substring_t args[MAX_OPT_ARGS];
    char *p = c;
    int token;
    int res;
    unsigned long handle;
    unsigned long lock;

    while ((p = strsep(&c, " \t"))) {
        if (*p == '\0' || *p == ' ' || *p == '\t')
            continue;
        token = match_token(p, key_tokens, args);

        switch (token) {
        case Opt_pcrinfo:
            opt->pcrinfo_len = strlen(args[0].from) / 2;
            if (opt->pcrinfo_len > MAX_PCRINFO_SIZE)
                return -EINVAL;
            res = hex2bin(opt->pcrinfo, args[0].from,
                      opt->pcrinfo_len);
            if (res < 0)
                return -EINVAL;
            break;
        case Opt_keyhandle:
            res = strict_strtoul(args[0].from, 16, &handle);
            if (res < 0)
                return -EINVAL;
            opt->keytype = SEAL_keytype;
            opt->keyhandle = handle;
            break;
        case Opt_keyauth:
            if (strlen(args[0].from) != 2 * SHA1_DIGEST_SIZE)
                return -EINVAL;
            res = hex2bin(opt->keyauth, args[0].from,
                      SHA1_DIGEST_SIZE);
            if (res < 0)
                return -EINVAL;
            break;
        case Opt_blobauth:
            if (strlen(args[0].from) != 2 * SHA1_DIGEST_SIZE)
                return -EINVAL;
            res = hex2bin(opt->blobauth, args[0].from,
                      SHA1_DIGEST_SIZE);
            if (res < 0)
                return -EINVAL;
            break;
        case Opt_migratable:
            if (*args[0].from == '0')
                pay->migratable = 0;
            else
                return -EINVAL;
            break;
        case Opt_pcrlock:
            res = strict_strtoul(args[0].from, 10, &lock);
            if (res < 0)
                return -EINVAL;
            opt->pcrlock = lock;
            break;
        default:
            return -EINVAL;
        }
    }
    return 0;
}

/*
 * datablob_parse - parse the keyctl data and fill in the
 *          payload and options structures
 *
 * On success returns 0, otherwise -EINVAL.
 */
static int datablob_parse(char *datablob, struct trusted_key_payload *p,
              struct trusted_key_options *o)
{
    substring_t args[MAX_OPT_ARGS];
    long keylen;
    int ret = -EINVAL;
    int key_cmd;
    char *c;

    /* main command */
    c = strsep(&datablob, " \t");
    if (!c)
        return -EINVAL;
    key_cmd = match_token(c, key_tokens, args);
    switch (key_cmd) {
    case Opt_new:
        /* first argument is key size */
        c = strsep(&datablob, " \t");
        if (!c)
            return -EINVAL;
        ret = strict_strtol(c, 10, &keylen);
        if (ret < 0 || keylen < MIN_KEY_SIZE || keylen > MAX_KEY_SIZE)
            return -EINVAL;
        p->key_len = keylen;
        ret = getoptions(datablob, p, o);
        if (ret < 0)
            return ret;
        ret = Opt_new;
        break;
    case Opt_load:
        /* first argument is sealed blob */
        c = strsep(&datablob, " \t");
        if (!c)
            return -EINVAL;
        p->blob_len = strlen(c) / 2;
        if (p->blob_len > MAX_BLOB_SIZE)
            return -EINVAL;
        ret = hex2bin(p->blob, c, p->blob_len);
        if (ret < 0)
            return -EINVAL;
        ret = getoptions(datablob, p, o);
        if (ret < 0)
            return ret;
        ret = Opt_load;
        break;
    case Opt_update:
        /* all arguments are options */
        ret = getoptions(datablob, p, o);
        if (ret < 0)
            return ret;
        ret = Opt_update;
        break;
    case Opt_err:
        return -EINVAL;
        break;
    }
    return ret;
}

static struct trusted_key_options *trusted_options_alloc(void)
{
    struct trusted_key_options *options;

    options = kzalloc(sizeof *options, GFP_KERNEL);
    if (options) {
        /* set any non-zero defaults */
        options->keytype = SRK_keytype;
        options->keyhandle = SRKHANDLE;
    }
    return options;
}

static struct trusted_key_payload *trusted_payload_alloc(struct key *key)
{
    struct trusted_key_payload *p = NULL;
    int ret;

    ret = key_payload_reserve(key, sizeof *p);
    if (ret < 0)
        return p;
    p = kzalloc(sizeof *p, GFP_KERNEL);
    if (p)
        p->migratable = 1; /* migratable by default */
    return p;
}

/*
 * trusted_instantiate - create a new trusted key
 *
 * Unseal an existing trusted blob or, for a new key, get a
 * random key, then seal and create a trusted key-type key,
 * adding it to the specified keyring.
 *
 * On success, return 0. Otherwise return errno.
 */
static int trusted_instantiate(struct key *key,
                   struct key_preparsed_payload *prep)
{
    struct trusted_key_payload *payload = NULL;
    struct trusted_key_options *options = NULL;
    size_t datalen = prep->datalen;
    char *datablob;
    int ret = 0;
    int key_cmd;
    size_t key_len;

    if (datalen <= 0 || datalen > 32767 || !prep->data)
        return -EINVAL;

    datablob = kmalloc(datalen + 1, GFP_KERNEL);
    if (!datablob)
        return -ENOMEM;
    memcpy(datablob, prep->data, datalen);
    datablob[datalen] = '\0';

    options = trusted_options_alloc();
    if (!options) {
        ret = -ENOMEM;
        goto out;
    }
    payload = trusted_payload_alloc(key);
    if (!payload) {
        ret = -ENOMEM;
        goto out;
    }

    key_cmd = datablob_parse(datablob, payload, options);
    if (key_cmd < 0) {
        ret = key_cmd;
        goto out;
    }

    dump_payload(payload);
    dump_options(options);

    switch (key_cmd) {
    case Opt_load:
        ret = key_unseal(payload, options);
        dump_payload(payload);
        dump_options(options);
        if (ret < 0)
            pr_info("trusted_key: key_unseal failed (%d)\n", ret);
        break;
    case Opt_new:
        key_len = payload->key_len;
        ret = tpm_get_random(TPM_ANY_NUM, payload->key, key_len);
        if (ret != key_len) {
            pr_info("trusted_key: key_create failed (%d)\n", ret);
            goto out;
        }
        ret = key_seal(payload, options);
        if (ret < 0)
            pr_info("trusted_key: key_seal failed (%d)\n", ret);
        break;
    default:
        ret = -EINVAL;
        goto out;
    }
    if (!ret && options->pcrlock)
        ret = pcrlock(options->pcrlock);
out:
    kfree(datablob);
    kfree(options);
    if (!ret)
        rcu_assign_keypointer(key, payload);
    else
        kfree(payload);
    return ret;
}

static void trusted_rcu_free(struct rcu_head *rcu)
{
    struct trusted_key_payload *p;

    p = container_of(rcu, struct trusted_key_payload, rcu);
    memset(p->key, 0, p->key_len);
    kfree(p);
}

/*
 * trusted_update - reseal an existing key with new PCR values
 */
static int trusted_update(struct key *key, struct key_preparsed_payload *prep)
{
    struct trusted_key_payload *p = key->payload.data;
    struct trusted_key_payload *new_p;
    struct trusted_key_options *new_o;
    size_t datalen = prep->datalen;
    char *datablob;
    int ret = 0;

    if (!p->migratable)
        return -EPERM;
    if (datalen <= 0 || datalen > 32767 || !prep->data)
        return -EINVAL;

    datablob = kmalloc(datalen + 1, GFP_KERNEL);
    if (!datablob)
        return -ENOMEM;
    new_o = trusted_options_alloc();
    if (!new_o) {
        ret = -ENOMEM;
        goto out;
    }
    new_p = trusted_payload_alloc(key);
    if (!new_p) {
        ret = -ENOMEM;
        goto out;
    }

    memcpy(datablob, prep->data, datalen);
    datablob[datalen] = '\0';
    ret = datablob_parse(datablob, new_p, new_o);
    if (ret != Opt_update) {
        ret = -EINVAL;
        kfree(new_p);
        goto out;
    }
    /* copy old key values, and reseal with new pcrs */
    new_p->migratable = p->migratable;
    new_p->key_len = p->key_len;
    memcpy(new_p->key, p->key, p->key_len);
    dump_payload(p);
    dump_payload(new_p);

    ret = key_seal(new_p, new_o);
    if (ret < 0) {
        pr_info("trusted_key: key_seal failed (%d)\n", ret);
        kfree(new_p);
        goto out;
    }
    if (new_o->pcrlock) {
        ret = pcrlock(new_o->pcrlock);
        if (ret < 0) {
            pr_info("trusted_key: pcrlock failed (%d)\n", ret);
            kfree(new_p);
            goto out;
        }
    }
    rcu_assign_keypointer(key, new_p);
    call_rcu(&p->rcu, trusted_rcu_free);
out:
    kfree(datablob);
    kfree(new_o);
    return ret;
}

/*
 * trusted_read - copy the sealed blob data to userspace in hex.
 * On success, return to userspace the trusted key datablob size.
 */
static long trusted_read(const struct key *key, char __user *buffer,
             size_t buflen)
{
    struct trusted_key_payload *p;
    char *ascii_buf;
    char *bufp;
    int i;

    p = rcu_dereference_key(key);
    if (!p)
        return -EINVAL;
    if (!buffer || buflen <= 0)
        return 2 * p->blob_len;
    ascii_buf = kmalloc(2 * p->blob_len, GFP_KERNEL);
    if (!ascii_buf)
        return -ENOMEM;

    bufp = ascii_buf;
    for (i = 0; i < p->blob_len; i++)
        bufp = hex_byte_pack(bufp, p->blob[i]);
    if ((copy_to_user(buffer, ascii_buf, 2 * p->blob_len)) != 0) {
        kfree(ascii_buf);
        return -EFAULT;
    }
    kfree(ascii_buf);
    return 2 * p->blob_len;
}

/*
 * trusted_destroy - before freeing the key, clear the decrypted data
 */
static void trusted_destroy(struct key *key)
{
    struct trusted_key_payload *p = key->payload.data;

    if (!p)
        return;
    memset(p->key, 0, p->key_len);
    kfree(key->payload.data);
}

struct key_type key_type_trusted = {
    .name = "trusted",
    .instantiate = trusted_instantiate,
    .update = trusted_update,
    .match = user_match,
    .destroy = trusted_destroy,
    .describe = user_describe,
    .read = trusted_read,
};

EXPORT_SYMBOL_GPL(key_type_trusted);

static void trusted_shash_release(void)
{
    if (hashalg)
        crypto_free_shash(hashalg);
    if (hmacalg)
        crypto_free_shash(hmacalg);
}

static int __init trusted_shash_alloc(void)
{
    int ret;

    hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC);
    if (IS_ERR(hmacalg)) {
        pr_info("trusted_key: could not allocate crypto %s\n",
            hmac_alg);
        return PTR_ERR(hmacalg);
    }

    hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC);
    if (IS_ERR(hashalg)) {
        pr_info("trusted_key: could not allocate crypto %s\n",
            hash_alg);
        ret = PTR_ERR(hashalg);
        goto hashalg_fail;
    }

    return 0;

hashalg_fail:
    crypto_free_shash(hmacalg);
    return ret;
}

static int __init init_trusted(void)
{
    int ret;

    ret = trusted_shash_alloc();
    if (ret < 0)
        return ret;
    ret = register_key_type(&key_type_trusted);
    if (ret < 0)
        trusted_shash_release();
    return ret;
}

static void __exit cleanup_trusted(void)
{
    trusted_shash_release();
    unregister_key_type(&key_type_trusted);
}

late_initcall(init_trusted);
module_exit(cleanup_trusted);

MODULE_LICENSE("GPL");