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// SPDX-License-Identifier: BSD-3-Clause
/*
* linux/net/sunrpc/gss_krb5_mech.c
*
* Copyright (c) 2001-2008 The Regents of the University of Michigan.
* All rights reserved.
*
* Andy Adamson <andros@umich.edu>
* J. Bruce Fields <bfields@umich.edu>
*/
#include <crypto/hash.h>
#include <crypto/skcipher.h>
#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 <kunit/visibility.h>
#include "auth_gss_internal.h"
#include "gss_krb5_internal.h"
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
# define RPCDBG_FACILITY RPCDBG_AUTH
#endif
static struct gss_api_mech gss_kerberos_mech;
static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
#if defined(CONFIG_RPCSEC_GSS_KRB5_ENCTYPES_AES_SHA1)
/*
* AES-128 with SHA-1 (RFC 3962)
*/
{
.etype = ENCTYPE_AES128_CTS_HMAC_SHA1_96,
.ctype = CKSUMTYPE_HMAC_SHA1_96_AES128,
.name = "aes128-cts",
.encrypt_name = "cts(cbc(aes))",
.aux_cipher = "cbc(aes)",
.cksum_name = "hmac(sha1)",
.derive_key = krb5_derive_key_v2,
.encrypt = gss_krb5_aes_encrypt,
.decrypt = gss_krb5_aes_decrypt,
.get_mic = gss_krb5_get_mic_v2,
.verify_mic = gss_krb5_verify_mic_v2,
.wrap = gss_krb5_wrap_v2,
.unwrap = gss_krb5_unwrap_v2,
.signalg = -1,
.sealalg = -1,
.keybytes = 16,
.keylength = BITS2OCTETS(128),
.Kc_length = BITS2OCTETS(128),
.Ke_length = BITS2OCTETS(128),
.Ki_length = BITS2OCTETS(128),
.cksumlength = BITS2OCTETS(96),
.keyed_cksum = 1,
},
/*
* AES-256 with SHA-1 (RFC 3962)
*/
{
.etype = ENCTYPE_AES256_CTS_HMAC_SHA1_96,
.ctype = CKSUMTYPE_HMAC_SHA1_96_AES256,
.name = "aes256-cts",
.encrypt_name = "cts(cbc(aes))",
.aux_cipher = "cbc(aes)",
.cksum_name = "hmac(sha1)",
.derive_key = krb5_derive_key_v2,
.encrypt = gss_krb5_aes_encrypt,
.decrypt = gss_krb5_aes_decrypt,
.get_mic = gss_krb5_get_mic_v2,
.verify_mic = gss_krb5_verify_mic_v2,
.wrap = gss_krb5_wrap_v2,
.unwrap = gss_krb5_unwrap_v2,
.signalg = -1,
.sealalg = -1,
.keybytes = 32,
.keylength = BITS2OCTETS(256),
.Kc_length = BITS2OCTETS(256),
.Ke_length = BITS2OCTETS(256),
.Ki_length = BITS2OCTETS(256),
.cksumlength = BITS2OCTETS(96),
.keyed_cksum = 1,
},
#endif
#if defined(CONFIG_RPCSEC_GSS_KRB5_ENCTYPES_CAMELLIA)
/*
* Camellia-128 with CMAC (RFC 6803)
*/
{
.etype = ENCTYPE_CAMELLIA128_CTS_CMAC,
.ctype = CKSUMTYPE_CMAC_CAMELLIA128,
.name = "camellia128-cts-cmac",
.encrypt_name = "cts(cbc(camellia))",
.aux_cipher = "cbc(camellia)",
.cksum_name = "cmac(camellia)",
.cksumlength = BITS2OCTETS(128),
.keyed_cksum = 1,
.keylength = BITS2OCTETS(128),
.Kc_length = BITS2OCTETS(128),
.Ke_length = BITS2OCTETS(128),
.Ki_length = BITS2OCTETS(128),
.derive_key = krb5_kdf_feedback_cmac,
.encrypt = gss_krb5_aes_encrypt,
.decrypt = gss_krb5_aes_decrypt,
.get_mic = gss_krb5_get_mic_v2,
.verify_mic = gss_krb5_verify_mic_v2,
.wrap = gss_krb5_wrap_v2,
.unwrap = gss_krb5_unwrap_v2,
},
/*
* Camellia-256 with CMAC (RFC 6803)
*/
{
.etype = ENCTYPE_CAMELLIA256_CTS_CMAC,
.ctype = CKSUMTYPE_CMAC_CAMELLIA256,
.name = "camellia256-cts-cmac",
.encrypt_name = "cts(cbc(camellia))",
.aux_cipher = "cbc(camellia)",
.cksum_name = "cmac(camellia)",
.cksumlength = BITS2OCTETS(128),
.keyed_cksum = 1,
.keylength = BITS2OCTETS(256),
.Kc_length = BITS2OCTETS(256),
.Ke_length = BITS2OCTETS(256),
.Ki_length = BITS2OCTETS(256),
.derive_key = krb5_kdf_feedback_cmac,
.encrypt = gss_krb5_aes_encrypt,
.decrypt = gss_krb5_aes_decrypt,
.get_mic = gss_krb5_get_mic_v2,
.verify_mic = gss_krb5_verify_mic_v2,
.wrap = gss_krb5_wrap_v2,
.unwrap = gss_krb5_unwrap_v2,
},
#endif
#if defined(CONFIG_RPCSEC_GSS_KRB5_ENCTYPES_AES_SHA2)
/*
* AES-128 with SHA-256 (RFC 8009)
*/
{
.etype = ENCTYPE_AES128_CTS_HMAC_SHA256_128,
.ctype = CKSUMTYPE_HMAC_SHA256_128_AES128,
.name = "aes128-cts-hmac-sha256-128",
.encrypt_name = "cts(cbc(aes))",
.aux_cipher = "cbc(aes)",
.cksum_name = "hmac(sha256)",
.cksumlength = BITS2OCTETS(128),
.keyed_cksum = 1,
.keylength = BITS2OCTETS(128),
.Kc_length = BITS2OCTETS(128),
.Ke_length = BITS2OCTETS(128),
.Ki_length = BITS2OCTETS(128),
.derive_key = krb5_kdf_hmac_sha2,
.encrypt = krb5_etm_encrypt,
.decrypt = krb5_etm_decrypt,
.get_mic = gss_krb5_get_mic_v2,
.verify_mic = gss_krb5_verify_mic_v2,
.wrap = gss_krb5_wrap_v2,
.unwrap = gss_krb5_unwrap_v2,
},
/*
* AES-256 with SHA-384 (RFC 8009)
*/
{
.etype = ENCTYPE_AES256_CTS_HMAC_SHA384_192,
.ctype = CKSUMTYPE_HMAC_SHA384_192_AES256,
.name = "aes256-cts-hmac-sha384-192",
.encrypt_name = "cts(cbc(aes))",
.aux_cipher = "cbc(aes)",
.cksum_name = "hmac(sha384)",
.cksumlength = BITS2OCTETS(192),
.keyed_cksum = 1,
.keylength = BITS2OCTETS(256),
.Kc_length = BITS2OCTETS(192),
.Ke_length = BITS2OCTETS(256),
.Ki_length = BITS2OCTETS(192),
.derive_key = krb5_kdf_hmac_sha2,
.encrypt = krb5_etm_encrypt,
.decrypt = krb5_etm_decrypt,
.get_mic = gss_krb5_get_mic_v2,
.verify_mic = gss_krb5_verify_mic_v2,
.wrap = gss_krb5_wrap_v2,
.unwrap = gss_krb5_unwrap_v2,
},
#endif
};
/*
* The list of advertised enctypes is specified in order of most
* preferred to least.
*/
static char gss_krb5_enctype_priority_list[64];
static void gss_krb5_prepare_enctype_priority_list(void)
{
static const u32 gss_krb5_enctypes[] = {
#if defined(CONFIG_RPCSEC_GSS_KRB5_ENCTYPES_AES_SHA2)
ENCTYPE_AES256_CTS_HMAC_SHA384_192,
ENCTYPE_AES128_CTS_HMAC_SHA256_128,
#endif
#if defined(CONFIG_RPCSEC_GSS_KRB5_ENCTYPES_CAMELLIA)
ENCTYPE_CAMELLIA256_CTS_CMAC,
ENCTYPE_CAMELLIA128_CTS_CMAC,
#endif
#if defined(CONFIG_RPCSEC_GSS_KRB5_ENCTYPES_AES_SHA1)
ENCTYPE_AES256_CTS_HMAC_SHA1_96,
ENCTYPE_AES128_CTS_HMAC_SHA1_96,
#endif
};
size_t total, i;
char buf[16];
char *sep;
int n;
sep = "";
gss_krb5_enctype_priority_list[0] = '\0';
for (total = 0, i = 0; i < ARRAY_SIZE(gss_krb5_enctypes); i++) {
n = sprintf(buf, "%s%u", sep, gss_krb5_enctypes[i]);
if (n < 0)
break;
if (total + n >= sizeof(gss_krb5_enctype_priority_list))
break;
strcat(gss_krb5_enctype_priority_list, buf);
sep = ",";
total += n;
}
}
/**
* gss_krb5_lookup_enctype - Retrieve profile information for a given enctype
* @etype: ENCTYPE value
*
* Returns a pointer to a gss_krb5_enctype structure, or NULL if no
* matching etype is found.
*/
VISIBLE_IF_KUNIT
const struct gss_krb5_enctype *gss_krb5_lookup_enctype(u32 etype)
{
size_t i;
for (i = 0; i < ARRAY_SIZE(supported_gss_krb5_enctypes); i++)
if (supported_gss_krb5_enctypes[i].etype == etype)
return &supported_gss_krb5_enctypes[i];
return NULL;
}
EXPORT_SYMBOL_IF_KUNIT(gss_krb5_lookup_enctype);
static struct crypto_sync_skcipher *
gss_krb5_alloc_cipher_v2(const char *cname, const struct xdr_netobj *key)
{
struct crypto_sync_skcipher *tfm;
tfm = crypto_alloc_sync_skcipher(cname, 0, 0);
if (IS_ERR(tfm))
return NULL;
if (crypto_sync_skcipher_setkey(tfm, key->data, key->len)) {
crypto_free_sync_skcipher(tfm);
return NULL;
}
return tfm;
}
static struct crypto_ahash *
gss_krb5_alloc_hash_v2(struct krb5_ctx *kctx, const struct xdr_netobj *key)
{
struct crypto_ahash *tfm;
tfm = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(tfm))
return NULL;
if (crypto_ahash_setkey(tfm, key->data, key->len)) {
crypto_free_ahash(tfm);
return NULL;
}
return tfm;
}
static int
gss_krb5_import_ctx_v2(struct krb5_ctx *ctx, gfp_t gfp_mask)
{
struct xdr_netobj keyin = {
.len = ctx->gk5e->keylength,
.data = ctx->Ksess,
};
struct xdr_netobj keyout;
int ret = -EINVAL;
keyout.data = kmalloc(GSS_KRB5_MAX_KEYLEN, gfp_mask);
if (!keyout.data)
return -ENOMEM;
/* initiator seal encryption */
keyout.len = ctx->gk5e->Ke_length;
if (krb5_derive_key(ctx, &keyin, &keyout, KG_USAGE_INITIATOR_SEAL,
KEY_USAGE_SEED_ENCRYPTION, gfp_mask))
goto out;
ctx->initiator_enc = gss_krb5_alloc_cipher_v2(ctx->gk5e->encrypt_name,
&keyout);
if (ctx->initiator_enc == NULL)
goto out;
if (ctx->gk5e->aux_cipher) {
ctx->initiator_enc_aux =
gss_krb5_alloc_cipher_v2(ctx->gk5e->aux_cipher,
&keyout);
if (ctx->initiator_enc_aux == NULL)
goto out_free;
}
/* acceptor seal encryption */
if (krb5_derive_key(ctx, &keyin, &keyout, KG_USAGE_ACCEPTOR_SEAL,
KEY_USAGE_SEED_ENCRYPTION, gfp_mask))
goto out_free;
ctx->acceptor_enc = gss_krb5_alloc_cipher_v2(ctx->gk5e->encrypt_name,
&keyout);
if (ctx->acceptor_enc == NULL)
goto out_free;
if (ctx->gk5e->aux_cipher) {
ctx->acceptor_enc_aux =
gss_krb5_alloc_cipher_v2(ctx->gk5e->aux_cipher,
&keyout);
if (ctx->acceptor_enc_aux == NULL)
goto out_free;
}
/* initiator sign checksum */
keyout.len = ctx->gk5e->Kc_length;
if (krb5_derive_key(ctx, &keyin, &keyout, KG_USAGE_INITIATOR_SIGN,
KEY_USAGE_SEED_CHECKSUM, gfp_mask))
goto out_free;
ctx->initiator_sign = gss_krb5_alloc_hash_v2(ctx, &keyout);
if (ctx->initiator_sign == NULL)
goto out_free;
/* acceptor sign checksum */
if (krb5_derive_key(ctx, &keyin, &keyout, KG_USAGE_ACCEPTOR_SIGN,
KEY_USAGE_SEED_CHECKSUM, gfp_mask))
goto out_free;
ctx->acceptor_sign = gss_krb5_alloc_hash_v2(ctx, &keyout);
if (ctx->acceptor_sign == NULL)
goto out_free;
/* initiator seal integrity */
keyout.len = ctx->gk5e->Ki_length;
if (krb5_derive_key(ctx, &keyin, &keyout, KG_USAGE_INITIATOR_SEAL,
KEY_USAGE_SEED_INTEGRITY, gfp_mask))
goto out_free;
ctx->initiator_integ = gss_krb5_alloc_hash_v2(ctx, &keyout);
if (ctx->initiator_integ == NULL)
goto out_free;
/* acceptor seal integrity */
if (krb5_derive_key(ctx, &keyin, &keyout, KG_USAGE_ACCEPTOR_SEAL,
KEY_USAGE_SEED_INTEGRITY, gfp_mask))
goto out_free;
ctx->acceptor_integ = gss_krb5_alloc_hash_v2(ctx, &keyout);
if (ctx->acceptor_integ == NULL)
goto out_free;
ret = 0;
out:
kfree_sensitive(keyout.data);
return ret;
out_free:
crypto_free_ahash(ctx->acceptor_integ);
crypto_free_ahash(ctx->initiator_integ);
crypto_free_ahash(ctx->acceptor_sign);
crypto_free_ahash(ctx->initiator_sign);
crypto_free_sync_skcipher(ctx->acceptor_enc_aux);
crypto_free_sync_skcipher(ctx->acceptor_enc);
crypto_free_sync_skcipher(ctx->initiator_enc_aux);
crypto_free_sync_skcipher(ctx->initiator_enc);
goto out;
}
static int
gss_import_v2_context(const void *p, const void *end, struct krb5_ctx *ctx,
gfp_t gfp_mask)
{
u64 seq_send64;
int keylen;
u32 time32;
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, &time32, sizeof(time32));
if (IS_ERR(p))
goto out_err;
/* unsigned 32-bit time overflows in year 2106 */
ctx->endtime = (time64_t)time32;
p = simple_get_bytes(p, end, &seq_send64, sizeof(seq_send64));
if (IS_ERR(p))
goto out_err;
atomic64_set(&ctx->seq_send64, seq_send64);
/* set seq_send for use by "older" enctypes */
atomic_set(&ctx->seq_send, seq_send64);
if (seq_send64 != atomic_read(&ctx->seq_send)) {
dprintk("%s: seq_send64 %llx, seq_send %x overflow?\n", __func__,
seq_send64, atomic_read(&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;
ctx->gk5e = gss_krb5_lookup_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;
return gss_krb5_import_ctx_v2(ctx, gfp_mask);
out_err:
return PTR_ERR(p);
}
static int
gss_krb5_import_sec_context(const void *p, size_t len, struct gss_ctx *ctx_id,
time64_t *endtime, 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;
ret = gss_import_v2_context(p, end, ctx, gfp_mask);
memzero_explicit(&ctx->Ksess, sizeof(ctx->Ksess));
if (ret) {
kfree(ctx);
return ret;
}
ctx_id->internal_ctx_id = ctx;
if (endtime)
*endtime = ctx->endtime;
return 0;
}
static void
gss_krb5_delete_sec_context(void *internal_ctx)
{
struct krb5_ctx *kctx = internal_ctx;
crypto_free_sync_skcipher(kctx->seq);
crypto_free_sync_skcipher(kctx->enc);
crypto_free_sync_skcipher(kctx->acceptor_enc);
crypto_free_sync_skcipher(kctx->initiator_enc);
crypto_free_sync_skcipher(kctx->acceptor_enc_aux);
crypto_free_sync_skcipher(kctx->initiator_enc_aux);
crypto_free_ahash(kctx->acceptor_sign);
crypto_free_ahash(kctx->initiator_sign);
crypto_free_ahash(kctx->acceptor_integ);
crypto_free_ahash(kctx->initiator_integ);
kfree(kctx->mech_used.data);
kfree(kctx);
}
/**
* gss_krb5_get_mic - get_mic for the Kerberos GSS mechanism
* @gctx: GSS context
* @text: plaintext to checksum
* @token: buffer into which to write the computed checksum
*
* Return values:
* %GSS_S_COMPLETE - success, and @token is filled in
* %GSS_S_FAILURE - checksum could not be generated
* %GSS_S_CONTEXT_EXPIRED - Kerberos context is no longer valid
*/
static u32 gss_krb5_get_mic(struct gss_ctx *gctx, struct xdr_buf *text,
struct xdr_netobj *token)
{
struct krb5_ctx *kctx = gctx->internal_ctx_id;
return kctx->gk5e->get_mic(kctx, text, token);
}
/**
* gss_krb5_verify_mic - verify_mic for the Kerberos GSS mechanism
* @gctx: GSS context
* @message_buffer: plaintext to check
* @read_token: received checksum to check
*
* Return values:
* %GSS_S_COMPLETE - computed and received checksums match
* %GSS_S_DEFECTIVE_TOKEN - received checksum is not valid
* %GSS_S_BAD_SIG - computed and received checksums do not match
* %GSS_S_FAILURE - received checksum could not be checked
* %GSS_S_CONTEXT_EXPIRED - Kerberos context is no longer valid
*/
static u32 gss_krb5_verify_mic(struct gss_ctx *gctx,
struct xdr_buf *message_buffer,
struct xdr_netobj *read_token)
{
struct krb5_ctx *kctx = gctx->internal_ctx_id;
return kctx->gk5e->verify_mic(kctx, message_buffer, read_token);
}
/**
* gss_krb5_wrap - gss_wrap for the Kerberos GSS mechanism
* @gctx: initialized GSS context
* @offset: byte offset in @buf to start writing the cipher text
* @buf: OUT: send buffer
* @pages: plaintext to wrap
*
* Return values:
* %GSS_S_COMPLETE - success, @buf has been updated
* %GSS_S_FAILURE - @buf could not be wrapped
* %GSS_S_CONTEXT_EXPIRED - Kerberos context is no longer valid
*/
static u32 gss_krb5_wrap(struct gss_ctx *gctx, int offset,
struct xdr_buf *buf, struct page **pages)
{
struct krb5_ctx *kctx = gctx->internal_ctx_id;
return kctx->gk5e->wrap(kctx, offset, buf, pages);
}
/**
* gss_krb5_unwrap - gss_unwrap for the Kerberos GSS mechanism
* @gctx: initialized GSS context
* @offset: starting byte offset into @buf
* @len: size of ciphertext to unwrap
* @buf: ciphertext to unwrap
*
* Return values:
* %GSS_S_COMPLETE - success, @buf has been updated
* %GSS_S_DEFECTIVE_TOKEN - received blob is not valid
* %GSS_S_BAD_SIG - computed and received checksums do not match
* %GSS_S_FAILURE - @buf could not be unwrapped
* %GSS_S_CONTEXT_EXPIRED - Kerberos context is no longer valid
*/
static u32 gss_krb5_unwrap(struct gss_ctx *gctx, int offset,
int len, struct xdr_buf *buf)
{
struct krb5_ctx *kctx = gctx->internal_ctx_id;
return kctx->gk5e->unwrap(kctx, offset, len, buf,
&gctx->slack, &gctx->align);
}
static const struct gss_api_ops gss_kerberos_ops = {
.gss_import_sec_context = gss_krb5_import_sec_context,
.gss_get_mic = gss_krb5_get_mic,
.gss_verify_mic = gss_krb5_verify_mic,
.gss_wrap = gss_krb5_wrap,
.gss_unwrap = gss_krb5_unwrap,
.gss_delete_sec_context = gss_krb5_delete_sec_context,
};
static struct pf_desc gss_kerberos_pfs[] = {
[0] = {
.pseudoflavor = RPC_AUTH_GSS_KRB5,
.qop = GSS_C_QOP_DEFAULT,
.service = RPC_GSS_SVC_NONE,
.name = "krb5",
},
[1] = {
.pseudoflavor = RPC_AUTH_GSS_KRB5I,
.qop = GSS_C_QOP_DEFAULT,
.service = RPC_GSS_SVC_INTEGRITY,
.name = "krb5i",
.datatouch = true,
},
[2] = {
.pseudoflavor = RPC_AUTH_GSS_KRB5P,
.qop = GSS_C_QOP_DEFAULT,
.service = RPC_GSS_SVC_PRIVACY,
.name = "krb5p",
.datatouch = true,
},
};
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");
MODULE_ALIAS("rpc-auth-gss-1.2.840.113554.1.2.2");
static struct gss_api_mech gss_kerberos_mech = {
.gm_name = "krb5",
.gm_owner = THIS_MODULE,
.gm_oid = { 9, "\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 = gss_krb5_enctype_priority_list,
};
static int __init init_kerberos_module(void)
{
int status;
gss_krb5_prepare_enctype_priority_list();
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_DESCRIPTION("Sun RPC Kerberos 5 module");
MODULE_LICENSE("GPL");
module_init(init_kerberos_module);
module_exit(cleanup_kerberos_module);