gss_krb5_mech.c

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/*
 *  linux/net/sunrpc/gss_krb5_mech.c
 *
 *  Copyright (c) 2001-2008 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Andy Adamson <[email protected]>
 *  J. Bruce Fields <[email protected]>
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. Neither the name of the University nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <linux/err.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/sunrpc/auth.h>
#include <linux/sunrpc/gss_krb5.h>
#include <linux/sunrpc/xdr.h>
#include <linux/crypto.h>
#include <linux/sunrpc/gss_krb5_enctypes.h>

#ifdef RPC_DEBUG
# define RPCDBG_FACILITY    RPCDBG_AUTH
#endif

static struct gss_api_mech gss_kerberos_mech;   /* forward declaration */

static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
    /*
     * DES (All DES enctypes are mapped to the same gss functionality)
     */
    {
      .etype = ENCTYPE_DES_CBC_RAW,
      .ctype = CKSUMTYPE_RSA_MD5,
      .name = "des-cbc-crc",
      .encrypt_name = "cbc(des)",
      .cksum_name = "md5",
      .encrypt = krb5_encrypt,
      .decrypt = krb5_decrypt,
      .mk_key = NULL,
      .signalg = SGN_ALG_DES_MAC_MD5,
      .sealalg = SEAL_ALG_DES,
      .keybytes = 7,
      .keylength = 8,
      .blocksize = 8,
      .conflen = 8,
      .cksumlength = 8,
      .keyed_cksum = 0,
    },
    /*
     * RC4-HMAC
     */
    {
      .etype = ENCTYPE_ARCFOUR_HMAC,
      .ctype = CKSUMTYPE_HMAC_MD5_ARCFOUR,
      .name = "rc4-hmac",
      .encrypt_name = "ecb(arc4)",
      .cksum_name = "hmac(md5)",
      .encrypt = krb5_encrypt,
      .decrypt = krb5_decrypt,
      .mk_key = NULL,
      .signalg = SGN_ALG_HMAC_MD5,
      .sealalg = SEAL_ALG_MICROSOFT_RC4,
      .keybytes = 16,
      .keylength = 16,
      .blocksize = 1,
      .conflen = 8,
      .cksumlength = 8,
      .keyed_cksum = 1,
    },
    /*
     * 3DES
     */
    {
      .etype = ENCTYPE_DES3_CBC_RAW,
      .ctype = CKSUMTYPE_HMAC_SHA1_DES3,
      .name = "des3-hmac-sha1",
      .encrypt_name = "cbc(des3_ede)",
      .cksum_name = "hmac(sha1)",
      .encrypt = krb5_encrypt,
      .decrypt = krb5_decrypt,
      .mk_key = gss_krb5_des3_make_key,
      .signalg = SGN_ALG_HMAC_SHA1_DES3_KD,
      .sealalg = SEAL_ALG_DES3KD,
      .keybytes = 21,
      .keylength = 24,
      .blocksize = 8,
      .conflen = 8,
      .cksumlength = 20,
      .keyed_cksum = 1,
    },
    /*
     * AES128
     */
    {
      .etype = ENCTYPE_AES128_CTS_HMAC_SHA1_96,
      .ctype = CKSUMTYPE_HMAC_SHA1_96_AES128,
      .name = "aes128-cts",
      .encrypt_name = "cts(cbc(aes))",
      .cksum_name = "hmac(sha1)",
      .encrypt = krb5_encrypt,
      .decrypt = krb5_decrypt,
      .mk_key = gss_krb5_aes_make_key,
      .encrypt_v2 = gss_krb5_aes_encrypt,
      .decrypt_v2 = gss_krb5_aes_decrypt,
      .signalg = -1,
      .sealalg = -1,
      .keybytes = 16,
      .keylength = 16,
      .blocksize = 16,
      .conflen = 16,
      .cksumlength = 12,
      .keyed_cksum = 1,
    },
    /*
     * AES256
     */
    {
      .etype = ENCTYPE_AES256_CTS_HMAC_SHA1_96,
      .ctype = CKSUMTYPE_HMAC_SHA1_96_AES256,
      .name = "aes256-cts",
      .encrypt_name = "cts(cbc(aes))",
      .cksum_name = "hmac(sha1)",
      .encrypt = krb5_encrypt,
      .decrypt = krb5_decrypt,
      .mk_key = gss_krb5_aes_make_key,
      .encrypt_v2 = gss_krb5_aes_encrypt,
      .decrypt_v2 = gss_krb5_aes_decrypt,
      .signalg = -1,
      .sealalg = -1,
      .keybytes = 32,
      .keylength = 32,
      .blocksize = 16,
      .conflen = 16,
      .cksumlength = 12,
      .keyed_cksum = 1,
    },
};

static const int num_supported_enctypes =
    ARRAY_SIZE(supported_gss_krb5_enctypes);

static int
supported_gss_krb5_enctype(int etype)
{
    int i;
    for (i = 0; i < num_supported_enctypes; i++)
        if (supported_gss_krb5_enctypes[i].etype == etype)
            return 1;
    return 0;
}

static const struct gss_krb5_enctype *
get_gss_krb5_enctype(int etype)
{
    int i;
    for (i = 0; i < num_supported_enctypes; i++)
        if (supported_gss_krb5_enctypes[i].etype == etype)
            return &supported_gss_krb5_enctypes[i];
    return NULL;
}

static const void *
simple_get_bytes(const void *p, const void *end, void *res, int len)
{
    const void *q = (const void *)((const char *)p + len);
    if (unlikely(q > end || q < p))
        return ERR_PTR(-EFAULT);
    memcpy(res, p, len);
    return q;
}

static const void *
simple_get_netobj(const void *p, const void *end, struct xdr_netobj *res)
{
    const void *q;
    unsigned int len;

    p = simple_get_bytes(p, end, &len, sizeof(len));
    if (IS_ERR(p))
        return p;
    q = (const void *)((const char *)p + len);
    if (unlikely(q > end || q < p))
        return ERR_PTR(-EFAULT);
    res->data = kmemdup(p, len, GFP_NOFS);
    if (unlikely(res->data == NULL))
        return ERR_PTR(-ENOMEM);
    res->len = len;
    return q;
}

static inline const void *
get_key(const void *p, const void *end,
    struct krb5_ctx *ctx, struct crypto_blkcipher **res)
{
    struct xdr_netobj   key;
    int         alg;

    p = simple_get_bytes(p, end, &alg, sizeof(alg));
    if (IS_ERR(p))
        goto out_err;

    switch (alg) {
    case ENCTYPE_DES_CBC_CRC:
    case ENCTYPE_DES_CBC_MD4:
    case ENCTYPE_DES_CBC_MD5:
        /* Map all these key types to ENCTYPE_DES_CBC_RAW */
        alg = ENCTYPE_DES_CBC_RAW;
        break;
    }

    if (!supported_gss_krb5_enctype(alg)) {
        printk(KERN_WARNING "gss_kerberos_mech: unsupported "
            "encryption key algorithm %d\n", alg);
        p = ERR_PTR(-EINVAL);
        goto out_err;
    }
    p = simple_get_netobj(p, end, &key);
    if (IS_ERR(p))
        goto out_err;

    *res = crypto_alloc_blkcipher(ctx->gk5e->encrypt_name, 0,
                            CRYPTO_ALG_ASYNC);
    if (IS_ERR(*res)) {
        printk(KERN_WARNING "gss_kerberos_mech: unable to initialize "
            "crypto algorithm %s\n", ctx->gk5e->encrypt_name);
        *res = NULL;
        goto out_err_free_key;
    }
    if (crypto_blkcipher_setkey(*res, key.data, key.len)) {
        printk(KERN_WARNING "gss_kerberos_mech: error setting key for "
            "crypto algorithm %s\n", ctx->gk5e->encrypt_name);
        goto out_err_free_tfm;
    }

    kfree(key.data);
    return p;

out_err_free_tfm:
    crypto_free_blkcipher(*res);
out_err_free_key:
    kfree(key.data);
    p = ERR_PTR(-EINVAL);
out_err:
    return p;
}

static int
gss_import_v1_context(const void *p, const void *end, struct krb5_ctx *ctx)
{
    int tmp;

    p = simple_get_bytes(p, end, &ctx->initiate, sizeof(ctx->initiate));
    if (IS_ERR(p))
        goto out_err;

    /* Old format supports only DES!  Any other enctype uses new format */
    ctx->enctype = ENCTYPE_DES_CBC_RAW;

    ctx->gk5e = get_gss_krb5_enctype(ctx->enctype);
    if (ctx->gk5e == NULL) {
        p = ERR_PTR(-EINVAL);
        goto out_err;
    }

    /* The downcall format was designed before we completely understood
     * the uses of the context fields; so it includes some stuff we
     * just give some minimal sanity-checking, and some we ignore
     * completely (like the next twenty bytes): */
    if (unlikely(p + 20 > end || p + 20 < p)) {
        p = ERR_PTR(-EFAULT);
        goto out_err;
    }
    p += 20;
    p = simple_get_bytes(p, end, &tmp, sizeof(tmp));
    if (IS_ERR(p))
        goto out_err;
    if (tmp != SGN_ALG_DES_MAC_MD5) {
        p = ERR_PTR(-ENOSYS);
        goto out_err;
    }
    p = simple_get_bytes(p, end, &tmp, sizeof(tmp));
    if (IS_ERR(p))
        goto out_err;
    if (tmp != SEAL_ALG_DES) {
        p = ERR_PTR(-ENOSYS);
        goto out_err;
    }
    p = simple_get_bytes(p, end, &ctx->endtime, sizeof(ctx->endtime));
    if (IS_ERR(p))
        goto out_err;
    p = simple_get_bytes(p, end, &ctx->seq_send, sizeof(ctx->seq_send));
    if (IS_ERR(p))
        goto out_err;
    p = simple_get_netobj(p, end, &ctx->mech_used);
    if (IS_ERR(p))
        goto out_err;
    p = get_key(p, end, ctx, &ctx->enc);
    if (IS_ERR(p))
        goto out_err_free_mech;
    p = get_key(p, end, ctx, &ctx->seq);
    if (IS_ERR(p))
        goto out_err_free_key1;
    if (p != end) {
        p = ERR_PTR(-EFAULT);
        goto out_err_free_key2;
    }

    return 0;

out_err_free_key2:
    crypto_free_blkcipher(ctx->seq);
out_err_free_key1:
    crypto_free_blkcipher(ctx->enc);
out_err_free_mech:
    kfree(ctx->mech_used.data);
out_err:
    return PTR_ERR(p);
}

static struct crypto_blkcipher *
context_v2_alloc_cipher(struct krb5_ctx *ctx, const char *cname, u8 *key)
{
    struct crypto_blkcipher *cp;

    cp = crypto_alloc_blkcipher(cname, 0, CRYPTO_ALG_ASYNC);
    if (IS_ERR(cp)) {
        dprintk("gss_kerberos_mech: unable to initialize "
            "crypto algorithm %s\n", cname);
        return NULL;
    }
    if (crypto_blkcipher_setkey(cp, key, ctx->gk5e->keylength)) {
        dprintk("gss_kerberos_mech: error setting key for "
            "crypto algorithm %s\n", cname);
        crypto_free_blkcipher(cp);
        return NULL;
    }
    return cp;
}

static inline void
set_cdata(u8 cdata[GSS_KRB5_K5CLENGTH], u32 usage, u8 seed)
{
    cdata[0] = (usage>>24)&0xff;
    cdata[1] = (usage>>16)&0xff;
    cdata[2] = (usage>>8)&0xff;
    cdata[3] = usage&0xff;
    cdata[4] = seed;
}

static int
context_derive_keys_des3(struct krb5_ctx *ctx, gfp_t gfp_mask)
{
    struct xdr_netobj c, keyin, keyout;
    u8 cdata[GSS_KRB5_K5CLENGTH];
    u32 err;

    c.len = GSS_KRB5_K5CLENGTH;
    c.data = cdata;

    keyin.data = ctx->Ksess;
    keyin.len = ctx->gk5e->keylength;
    keyout.len = ctx->gk5e->keylength;

    /* seq uses the raw key */
    ctx->seq = context_v2_alloc_cipher(ctx, ctx->gk5e->encrypt_name,
                       ctx->Ksess);
    if (ctx->seq == NULL)
        goto out_err;

    ctx->enc = context_v2_alloc_cipher(ctx, ctx->gk5e->encrypt_name,
                       ctx->Ksess);
    if (ctx->enc == NULL)
        goto out_free_seq;

    /* derive cksum */
    set_cdata(cdata, KG_USAGE_SIGN, KEY_USAGE_SEED_CHECKSUM);
    keyout.data = ctx->cksum;
    err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask);
    if (err) {
        dprintk("%s: Error %d deriving cksum key\n",
            __func__, err);
        goto out_free_enc;
    }

    return 0;

out_free_enc:
    crypto_free_blkcipher(ctx->enc);
out_free_seq:
    crypto_free_blkcipher(ctx->seq);
out_err:
    return -EINVAL;
}

/*
 * Note that RC4 depends on deriving keys using the sequence
 * number or the checksum of a token.  Therefore, the final keys
 * cannot be calculated until the token is being constructed!
 */
static int
context_derive_keys_rc4(struct krb5_ctx *ctx)
{
    struct crypto_hash *hmac;
    char sigkeyconstant[] = "signaturekey";
    int slen = strlen(sigkeyconstant) + 1;  /* include null terminator */
    struct hash_desc desc;
    struct scatterlist sg[1];
    int err;

    dprintk("RPC:       %s: entered\n", __func__);
    /*
     * derive cksum (aka Ksign) key
     */
    hmac = crypto_alloc_hash(ctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
    if (IS_ERR(hmac)) {
        dprintk("%s: error %ld allocating hash '%s'\n",
            __func__, PTR_ERR(hmac), ctx->gk5e->cksum_name);
        err = PTR_ERR(hmac);
        goto out_err;
    }

    err = crypto_hash_setkey(hmac, ctx->Ksess, ctx->gk5e->keylength);
    if (err)
        goto out_err_free_hmac;

    sg_init_table(sg, 1);
    sg_set_buf(sg, sigkeyconstant, slen);

    desc.tfm = hmac;
    desc.flags = 0;

    err = crypto_hash_init(&desc);
    if (err)
        goto out_err_free_hmac;

    err = crypto_hash_digest(&desc, sg, slen, ctx->cksum);
    if (err)
        goto out_err_free_hmac;
    /*
     * allocate hash, and blkciphers for data and seqnum encryption
     */
    ctx->enc = crypto_alloc_blkcipher(ctx->gk5e->encrypt_name, 0,
                      CRYPTO_ALG_ASYNC);
    if (IS_ERR(ctx->enc)) {
        err = PTR_ERR(ctx->enc);
        goto out_err_free_hmac;
    }

    ctx->seq = crypto_alloc_blkcipher(ctx->gk5e->encrypt_name, 0,
                      CRYPTO_ALG_ASYNC);
    if (IS_ERR(ctx->seq)) {
        crypto_free_blkcipher(ctx->enc);
        err = PTR_ERR(ctx->seq);
        goto out_err_free_hmac;
    }

    dprintk("RPC:       %s: returning success\n", __func__);

    err = 0;

out_err_free_hmac:
    crypto_free_hash(hmac);
out_err:
    dprintk("RPC:       %s: returning %d\n", __func__, err);
    return err;
}

static int
context_derive_keys_new(struct krb5_ctx *ctx, gfp_t gfp_mask)
{
    struct xdr_netobj c, keyin, keyout;
    u8 cdata[GSS_KRB5_K5CLENGTH];
    u32 err;

    c.len = GSS_KRB5_K5CLENGTH;
    c.data = cdata;

    keyin.data = ctx->Ksess;
    keyin.len = ctx->gk5e->keylength;
    keyout.len = ctx->gk5e->keylength;

    /* initiator seal encryption */
    set_cdata(cdata, KG_USAGE_INITIATOR_SEAL, KEY_USAGE_SEED_ENCRYPTION);
    keyout.data = ctx->initiator_seal;
    err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask);
    if (err) {
        dprintk("%s: Error %d deriving initiator_seal key\n",
            __func__, err);
        goto out_err;
    }
    ctx->initiator_enc = context_v2_alloc_cipher(ctx,
                             ctx->gk5e->encrypt_name,
                             ctx->initiator_seal);
    if (ctx->initiator_enc == NULL)
        goto out_err;

    /* acceptor seal encryption */
    set_cdata(cdata, KG_USAGE_ACCEPTOR_SEAL, KEY_USAGE_SEED_ENCRYPTION);
    keyout.data = ctx->acceptor_seal;
    err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask);
    if (err) {
        dprintk("%s: Error %d deriving acceptor_seal key\n",
            __func__, err);
        goto out_free_initiator_enc;
    }
    ctx->acceptor_enc = context_v2_alloc_cipher(ctx,
                            ctx->gk5e->encrypt_name,
                            ctx->acceptor_seal);
    if (ctx->acceptor_enc == NULL)
        goto out_free_initiator_enc;

    /* initiator sign checksum */
    set_cdata(cdata, KG_USAGE_INITIATOR_SIGN, KEY_USAGE_SEED_CHECKSUM);
    keyout.data = ctx->initiator_sign;
    err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask);
    if (err) {
        dprintk("%s: Error %d deriving initiator_sign key\n",
            __func__, err);
        goto out_free_acceptor_enc;
    }

    /* acceptor sign checksum */
    set_cdata(cdata, KG_USAGE_ACCEPTOR_SIGN, KEY_USAGE_SEED_CHECKSUM);
    keyout.data = ctx->acceptor_sign;
    err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask);
    if (err) {
        dprintk("%s: Error %d deriving acceptor_sign key\n",
            __func__, err);
        goto out_free_acceptor_enc;
    }

    /* initiator seal integrity */
    set_cdata(cdata, KG_USAGE_INITIATOR_SEAL, KEY_USAGE_SEED_INTEGRITY);
    keyout.data = ctx->initiator_integ;
    err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask);
    if (err) {
        dprintk("%s: Error %d deriving initiator_integ key\n",
            __func__, err);
        goto out_free_acceptor_enc;
    }

    /* acceptor seal integrity */
    set_cdata(cdata, KG_USAGE_ACCEPTOR_SEAL, KEY_USAGE_SEED_INTEGRITY);
    keyout.data = ctx->acceptor_integ;
    err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask);
    if (err) {
        dprintk("%s: Error %d deriving acceptor_integ key\n",
            __func__, err);
        goto out_free_acceptor_enc;
    }

    switch (ctx->enctype) {
    case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
    case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
        ctx->initiator_enc_aux =
            context_v2_alloc_cipher(ctx, "cbc(aes)",
                        ctx->initiator_seal);
        if (ctx->initiator_enc_aux == NULL)
            goto out_free_acceptor_enc;
        ctx->acceptor_enc_aux =
            context_v2_alloc_cipher(ctx, "cbc(aes)",
                        ctx->acceptor_seal);
        if (ctx->acceptor_enc_aux == NULL) {
            crypto_free_blkcipher(ctx->initiator_enc_aux);
            goto out_free_acceptor_enc;
        }
    }

    return 0;

out_free_acceptor_enc:
    crypto_free_blkcipher(ctx->acceptor_enc);
out_free_initiator_enc:
    crypto_free_blkcipher(ctx->initiator_enc);
out_err:
    return -EINVAL;
}

static int
gss_import_v2_context(const void *p, const void *end, struct krb5_ctx *ctx,
        gfp_t gfp_mask)
{
    int keylen;

    p = simple_get_bytes(p, end, &ctx->flags, sizeof(ctx->flags));
    if (IS_ERR(p))
        goto out_err;
    ctx->initiate = ctx->flags & KRB5_CTX_FLAG_INITIATOR;

    p = simple_get_bytes(p, end, &ctx->endtime, sizeof(ctx->endtime));
    if (IS_ERR(p))
        goto out_err;
    p = simple_get_bytes(p, end, &ctx->seq_send64, sizeof(ctx->seq_send64));
    if (IS_ERR(p))
        goto out_err;
    /* set seq_send for use by "older" enctypes */
    ctx->seq_send = ctx->seq_send64;
    if (ctx->seq_send64 != ctx->seq_send) {
        dprintk("%s: seq_send64 %lx, seq_send %x overflow?\n", __func__,
            (unsigned long)ctx->seq_send64, ctx->seq_send);
        p = ERR_PTR(-EINVAL);
        goto out_err;
    }
    p = simple_get_bytes(p, end, &ctx->enctype, sizeof(ctx->enctype));
    if (IS_ERR(p))
        goto out_err;
    /* Map ENCTYPE_DES3_CBC_SHA1 to ENCTYPE_DES3_CBC_RAW */
    if (ctx->enctype == ENCTYPE_DES3_CBC_SHA1)
        ctx->enctype = ENCTYPE_DES3_CBC_RAW;
    ctx->gk5e = get_gss_krb5_enctype(ctx->enctype);
    if (ctx->gk5e == NULL) {
        dprintk("gss_kerberos_mech: unsupported krb5 enctype %u\n",
            ctx->enctype);
        p = ERR_PTR(-EINVAL);
        goto out_err;
    }
    keylen = ctx->gk5e->keylength;

    p = simple_get_bytes(p, end, ctx->Ksess, keylen);
    if (IS_ERR(p))
        goto out_err;

    if (p != end) {
        p = ERR_PTR(-EINVAL);
        goto out_err;
    }

    ctx->mech_used.data = kmemdup(gss_kerberos_mech.gm_oid.data,
                      gss_kerberos_mech.gm_oid.len, gfp_mask);
    if (unlikely(ctx->mech_used.data == NULL)) {
        p = ERR_PTR(-ENOMEM);
        goto out_err;
    }
    ctx->mech_used.len = gss_kerberos_mech.gm_oid.len;

    switch (ctx->enctype) {
    case ENCTYPE_DES3_CBC_RAW:
        return context_derive_keys_des3(ctx, gfp_mask);
    case ENCTYPE_ARCFOUR_HMAC:
        return context_derive_keys_rc4(ctx);
    case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
    case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
        return context_derive_keys_new(ctx, gfp_mask);
    default:
        return -EINVAL;
    }

out_err:
    return PTR_ERR(p);
}

static int
gss_import_sec_context_kerberos(const void *p, size_t len,
                struct gss_ctx *ctx_id,
                gfp_t gfp_mask)
{
    const void *end = (const void *)((const char *)p + len);
    struct  krb5_ctx *ctx;
    int ret;

    ctx = kzalloc(sizeof(*ctx), gfp_mask);
    if (ctx == NULL)
        return -ENOMEM;

    if (len == 85)
        ret = gss_import_v1_context(p, end, ctx);
    else
        ret = gss_import_v2_context(p, end, ctx, gfp_mask);

    if (ret == 0)
        ctx_id->internal_ctx_id = ctx;
    else
        kfree(ctx);

    dprintk("RPC:       %s: returning %d\n", __func__, ret);
    return ret;
}

static void
gss_delete_sec_context_kerberos(void *internal_ctx) {
    struct krb5_ctx *kctx = internal_ctx;

    crypto_free_blkcipher(kctx->seq);
    crypto_free_blkcipher(kctx->enc);
    crypto_free_blkcipher(kctx->acceptor_enc);
    crypto_free_blkcipher(kctx->initiator_enc);
    crypto_free_blkcipher(kctx->acceptor_enc_aux);
    crypto_free_blkcipher(kctx->initiator_enc_aux);
    kfree(kctx->mech_used.data);
    kfree(kctx);
}

static const struct gss_api_ops gss_kerberos_ops = {
    .gss_import_sec_context = gss_import_sec_context_kerberos,
    .gss_get_mic        = gss_get_mic_kerberos,
    .gss_verify_mic     = gss_verify_mic_kerberos,
    .gss_wrap       = gss_wrap_kerberos,
    .gss_unwrap     = gss_unwrap_kerberos,
    .gss_delete_sec_context = gss_delete_sec_context_kerberos,
};

static struct pf_desc gss_kerberos_pfs[] = {
    [0] = {
        .pseudoflavor = RPC_AUTH_GSS_KRB5,
        .service = RPC_GSS_SVC_NONE,
        .name = "krb5",
    },
    [1] = {
        .pseudoflavor = RPC_AUTH_GSS_KRB5I,
        .service = RPC_GSS_SVC_INTEGRITY,
        .name = "krb5i",
    },
    [2] = {
        .pseudoflavor = RPC_AUTH_GSS_KRB5P,
        .service = RPC_GSS_SVC_PRIVACY,
        .name = "krb5p",
    },
};

MODULE_ALIAS("rpc-auth-gss-krb5");
MODULE_ALIAS("rpc-auth-gss-krb5i");
MODULE_ALIAS("rpc-auth-gss-krb5p");
MODULE_ALIAS("rpc-auth-gss-390003");
MODULE_ALIAS("rpc-auth-gss-390004");
MODULE_ALIAS("rpc-auth-gss-390005");

static struct gss_api_mech gss_kerberos_mech = {
    .gm_name    = "krb5",
    .gm_owner   = THIS_MODULE,
    .gm_oid     = {9, (void *)"\x2a\x86\x48\x86\xf7\x12\x01\x02\x02"},
    .gm_ops     = &gss_kerberos_ops,
    .gm_pf_num  = ARRAY_SIZE(gss_kerberos_pfs),
    .gm_pfs     = gss_kerberos_pfs,
    .gm_upcall_enctypes = KRB5_SUPPORTED_ENCTYPES,
};

static int __init init_kerberos_module(void)
{
    int status;

    status = gss_mech_register(&gss_kerberos_mech);
    if (status)
        printk("Failed to register kerberos gss mechanism!\n");
    return status;
}

static void __exit cleanup_kerberos_module(void)
{
    gss_mech_unregister(&gss_kerberos_mech);
}

MODULE_LICENSE("GPL");
module_init(init_kerberos_module);
module_exit(cleanup_kerberos_module);