RxRPC: Allow key payloads to be passed in XDR form

Allow add_key() and KEYCTL_INSTANTIATE to accept key payloads in XDR form as
described by openafs-1.4.10/src/auth/afs_token.xg.  This provides a way of
passing kaserver, Kerberos 4, Kerberos 5 and GSSAPI keys from userspace, and
allows for future expansion.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/keys/rxrpc-type.h b/include/keys/rxrpc-type.h
index 7609365..c0d9121 100644 (file)
--- a/include/keys/rxrpc-type.h
+++ b/include/keys/rxrpc-type.h
@@ -21,4 +21,59 @@ extern struct key_type key_type_rxrpc;
 
 extern struct key *rxrpc_get_null_key(const char *);
 
+/*
+ * RxRPC key for Kerberos IV (type-2 security)
+ */
+struct rxkad_key {
+       u32     vice_id;
+       u32     start;                  /* time at which ticket starts */
+       u32     expiry;                 /* time at which ticket expires */
+       u32     kvno;                   /* key version number */
+       u8      primary_flag;           /* T if key for primary cell for this user */
+       u16     ticket_len;             /* length of ticket[] */
+       u8      session_key[8];         /* DES session key */
+       u8      ticket[0];              /* the encrypted ticket */
+};
+
+/*
+ * list of tokens attached to an rxrpc key
+ */
+struct rxrpc_key_token {
+       u16     security_index;         /* RxRPC header security index */
+       struct rxrpc_key_token *next;   /* the next token in the list */
+       union {
+               struct rxkad_key *kad;
+       };
+};
+
+/*
+ * structure of raw payloads passed to add_key() or instantiate key
+ */
+struct rxrpc_key_data_v1 {
+       u32             kif_version;            /* 1 */
+       u16             security_index;
+       u16             ticket_length;
+       u32             expiry;                 /* time_t */
+       u32             kvno;
+       u8              session_key[8];
+       u8              ticket[0];
+};
+
+/*
+ * AF_RXRPC key payload derived from XDR format
+ * - based on openafs-1.4.10/src/auth/afs_token.xg
+ */
+#define AFSTOKEN_LENGTH_MAX            16384   /* max payload size */
+#define AFSTOKEN_CELL_MAX              64      /* max cellname length */
+#define AFSTOKEN_MAX                   8       /* max tokens per payload */
+#define AFSTOKEN_RK_TIX_MAX            12000   /* max RxKAD ticket size */
+#define AFSTOKEN_GK_KEY_MAX            64      /* max GSSAPI key size */
+#define AFSTOKEN_GK_TOKEN_MAX          16384   /* max GSSAPI token size */
+#define AFSTOKEN_K5_COMPONENTS_MAX     16      /* max K5 components */
+#define AFSTOKEN_K5_NAME_MAX           128     /* max K5 name length */
+#define AFSTOKEN_K5_REALM_MAX          64      /* max K5 realm name length */
+#define AFSTOKEN_K5_TIX_MAX            16384   /* max K5 ticket size */
+#define AFSTOKEN_K5_ADDRESSES_MAX      16      /* max K5 addresses */
+#define AFSTOKEN_K5_AUTHDATA_MAX       16      /* max K5 pieces of auth data */
+
 #endif /* _KEYS_RXRPC_TYPE_H */

diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 3e7318c..46c6d88 100644 (file)
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -402,22 +402,6 @@ struct rxrpc_call {
 };
 
 /*
- * RxRPC key for Kerberos (type-2 security)
- */
-struct rxkad_key {
-       u16     security_index;         /* RxRPC header security index */
-       u16     ticket_len;             /* length of ticket[] */
-       u32     expiry;                 /* time at which expires */
-       u32     kvno;                   /* key version number */
-       u8      session_key[8];         /* DES session key */
-       u8      ticket[0];              /* the encrypted ticket */
-};
-
-struct rxrpc_key_payload {
-       struct rxkad_key k;
-};
-
-/*
  * locally abort an RxRPC call
  */
 static inline void rxrpc_abort_call(struct rxrpc_call *call, u32 abort_code)

diff --git a/net/rxrpc/ar-key.c b/net/rxrpc/ar-key.c
index b3d10e7..a3a7acb 100644 (file)
--- a/net/rxrpc/ar-key.c
+++ b/net/rxrpc/ar-key.c
@@ -17,6 +17,7 @@
 #include <linux/skbuff.h>
 #include <linux/key-type.h>
 #include <linux/crypto.h>
+#include <linux/ctype.h>
 #include <net/sock.h>
 #include <net/af_rxrpc.h>
 #include <keys/rxrpc-type.h>
@@ -55,6 +56,202 @@ struct key_type key_type_rxrpc_s = {
 };
 
 /*
+ * parse an RxKAD type XDR format token
+ * - the caller guarantees we have at least 4 words
+ */
+static int rxrpc_instantiate_xdr_rxkad(struct key *key, const __be32 *xdr,
+                                      unsigned toklen)
+{
+       struct rxrpc_key_token *token;
+       size_t plen;
+       u32 tktlen;
+       int ret;
+
+       _enter(",{%x,%x,%x,%x},%u",
+              ntohl(xdr[0]), ntohl(xdr[1]), ntohl(xdr[2]), ntohl(xdr[3]),
+              toklen);
+
+       if (toklen <= 8 * 4)
+               return -EKEYREJECTED;
+       tktlen = ntohl(xdr[7]);
+       _debug("tktlen: %x", tktlen);
+       if (tktlen > AFSTOKEN_RK_TIX_MAX)
+               return -EKEYREJECTED;
+       if (8 * 4 + tktlen != toklen)
+               return -EKEYREJECTED;
+
+       plen = sizeof(*token) + sizeof(*token->kad) + tktlen;
+       ret = key_payload_reserve(key, key->datalen + plen);
+       if (ret < 0)
+               return ret;
+
+       plen -= sizeof(*token);
+       token = kmalloc(sizeof(*token), GFP_KERNEL);
+       if (!token)
+               return -ENOMEM;
+
+       token->kad = kmalloc(plen, GFP_KERNEL);
+       if (!token->kad) {
+               kfree(token);
+               return -ENOMEM;
+       }
+
+       token->security_index   = RXRPC_SECURITY_RXKAD;
+       token->kad->ticket_len  = tktlen;
+       token->kad->vice_id     = ntohl(xdr[0]);
+       token->kad->kvno        = ntohl(xdr[1]);
+       token->kad->start       = ntohl(xdr[4]);
+       token->kad->expiry      = ntohl(xdr[5]);
+       token->kad->primary_flag = ntohl(xdr[6]);
+       memcpy(&token->kad->session_key, &xdr[2], 8);
+       memcpy(&token->kad->ticket, &xdr[8], tktlen);
+
+       _debug("SCIX: %u", token->security_index);
+       _debug("TLEN: %u", token->kad->ticket_len);
+       _debug("EXPY: %x", token->kad->expiry);
+       _debug("KVNO: %u", token->kad->kvno);
+       _debug("PRIM: %u", token->kad->primary_flag);
+       _debug("SKEY: %02x%02x%02x%02x%02x%02x%02x%02x",
+              token->kad->session_key[0], token->kad->session_key[1],
+              token->kad->session_key[2], token->kad->session_key[3],
+              token->kad->session_key[4], token->kad->session_key[5],
+              token->kad->session_key[6], token->kad->session_key[7]);
+       if (token->kad->ticket_len >= 8)
+               _debug("TCKT: %02x%02x%02x%02x%02x%02x%02x%02x",
+                      token->kad->ticket[0], token->kad->ticket[1],
+                      token->kad->ticket[2], token->kad->ticket[3],
+                      token->kad->ticket[4], token->kad->ticket[5],
+                      token->kad->ticket[6], token->kad->ticket[7]);
+
+       /* count the number of tokens attached */
+       key->type_data.x[0]++;
+
+       /* attach the data */
+       token->next = key->payload.data;
+       key->payload.data = token;
+       if (token->kad->expiry < key->expiry)
+               key->expiry = token->kad->expiry;
+
+       _leave(" = 0");
+       return 0;
+}
+
+/*
+ * attempt to parse the data as the XDR format
+ * - the caller guarantees we have more than 7 words
+ */
+static int rxrpc_instantiate_xdr(struct key *key, const void *data, size_t datalen)
+{
+       const __be32 *xdr = data, *token;
+       const char *cp;
+       unsigned len, tmp, loop, ntoken, toklen, sec_ix;
+       int ret;
+
+       _enter(",{%x,%x,%x,%x},%zu",
+              ntohl(xdr[0]), ntohl(xdr[1]), ntohl(xdr[2]), ntohl(xdr[3]),
+              datalen);
+
+       if (datalen > AFSTOKEN_LENGTH_MAX)
+               goto not_xdr;
+
+       /* XDR is an array of __be32's */
+       if (datalen & 3)
+               goto not_xdr;
+
+       /* the flags should be 0 (the setpag bit must be handled by
+        * userspace) */
+       if (ntohl(*xdr++) != 0)
+               goto not_xdr;
+       datalen -= 4;
+
+       /* check the cell name */
+       len = ntohl(*xdr++);
+       if (len < 1 || len > AFSTOKEN_CELL_MAX)
+               goto not_xdr;
+       datalen -= 4;
+       tmp = (len + 3) & ~3;
+       if (tmp > datalen)
+               goto not_xdr;
+
+       cp = (const char *) xdr;
+       for (loop = 0; loop < len; loop++)
+               if (!isprint(cp[loop]))
+                       goto not_xdr;
+       if (len < tmp)
+               for (; loop < tmp; loop++)
+                       if (cp[loop])
+                               goto not_xdr;
+       _debug("cellname: [%u/%u] '%*.*s'",
+              len, tmp, len, len, (const char *) xdr);
+       datalen -= tmp;
+       xdr += tmp >> 2;
+
+       /* get the token count */
+       if (datalen < 12)
+               goto not_xdr;
+       ntoken = ntohl(*xdr++);
+       datalen -= 4;
+       _debug("ntoken: %x", ntoken);
+       if (ntoken < 1 || ntoken > AFSTOKEN_MAX)
+               goto not_xdr;
+
+       /* check each token wrapper */
+       token = xdr;
+       loop = ntoken;
+       do {
+               if (datalen < 8)
+                       goto not_xdr;
+               toklen = ntohl(*xdr++);
+               sec_ix = ntohl(*xdr);
+               datalen -= 4;
+               _debug("token: [%x/%zx] %x", toklen, datalen, sec_ix);
+               if (toklen < 20 || toklen > datalen)
+                       goto not_xdr;
+               datalen -= (toklen + 3) & ~3;
+               xdr += (toklen + 3) >> 2;
+
+       } while (--loop > 0);
+
+       _debug("remainder: %zu", datalen);
+       if (datalen != 0)
+               goto not_xdr;
+
+       /* okay: we're going to assume it's valid XDR format
+        * - we ignore the cellname, relying on the key to be correctly named
+        */
+       do {
+               xdr = token;
+               toklen = ntohl(*xdr++);
+               token = xdr + ((toklen + 3) >> 2);
+               sec_ix = ntohl(*xdr++);
+               toklen -= 4;
+
+               switch (sec_ix) {
+               case RXRPC_SECURITY_RXKAD:
+                       ret = rxrpc_instantiate_xdr_rxkad(key, xdr, toklen);
+                       if (ret != 0)
+                               goto error;
+                       break;
+
+               default:
+                       ret = -EPROTONOSUPPORT;
+                       goto error;
+               }
+
+       } while (--ntoken > 0);
+
+       _leave(" = 0");
+       return 0;
+
+not_xdr:
+       _leave(" = -EPROTO");
+       return -EPROTO;
+error:
+       _leave(" = %d", ret);
+       return ret;
+}
+
+/*
  * instantiate an rxrpc defined key
  * data should be of the form:
  *     OFFSET  LEN     CONTENT
@@ -70,8 +267,8 @@ struct key_type key_type_rxrpc_s = {
  */
 static int rxrpc_instantiate(struct key *key, const void *data, size_t datalen)
 {
-       const struct rxkad_key *tsec;
-       struct rxrpc_key_payload *upayload;
+       const struct rxrpc_key_data_v1 *v1;
+       struct rxrpc_key_token *token, **pp;
        size_t plen;
        u32 kver;
        int ret;
@@ -82,6 +279,13 @@ static int rxrpc_instantiate(struct key *key, const void *data, size_t datalen)
        if (!data && datalen == 0)
                return 0;
 
+       /* determine if the XDR payload format is being used */
+       if (datalen > 7 * 4) {
+               ret = rxrpc_instantiate_xdr(key, data, datalen);
+               if (ret != -EPROTO)
+                       return ret;
+       }
+
        /* get the key interface version number */
        ret = -EINVAL;
        if (datalen <= 4 || !data)
@@ -98,53 +302,67 @@ static int rxrpc_instantiate(struct key *key, const void *data, size_t datalen)
 
        /* deal with a version 1 key */
        ret = -EINVAL;
-       if (datalen < sizeof(*tsec))
+       if (datalen < sizeof(*v1))
                goto error;
 
-       tsec = data;
-       if (datalen != sizeof(*tsec) + tsec->ticket_len)
+       v1 = data;
+       if (datalen != sizeof(*v1) + v1->ticket_length)
                goto error;
 
-       _debug("SCIX: %u", tsec->security_index);
-       _debug("TLEN: %u", tsec->ticket_len);
-       _debug("EXPY: %x", tsec->expiry);
-       _debug("KVNO: %u", tsec->kvno);
+       _debug("SCIX: %u", v1->security_index);
+       _debug("TLEN: %u", v1->ticket_length);
+       _debug("EXPY: %x", v1->expiry);
+       _debug("KVNO: %u", v1->kvno);
        _debug("SKEY: %02x%02x%02x%02x%02x%02x%02x%02x",
-              tsec->session_key[0], tsec->session_key[1],
-              tsec->session_key[2], tsec->session_key[3],
-              tsec->session_key[4], tsec->session_key[5],
-              tsec->session_key[6], tsec->session_key[7]);
-       if (tsec->ticket_len >= 8)
+              v1->session_key[0], v1->session_key[1],
+              v1->session_key[2], v1->session_key[3],
+              v1->session_key[4], v1->session_key[5],
+              v1->session_key[6], v1->session_key[7]);
+       if (v1->ticket_length >= 8)
                _debug("TCKT: %02x%02x%02x%02x%02x%02x%02x%02x",
-                      tsec->ticket[0], tsec->ticket[1],
-                      tsec->ticket[2], tsec->ticket[3],
-                      tsec->ticket[4], tsec->ticket[5],
-                      tsec->ticket[6], tsec->ticket[7]);
+                      v1->ticket[0], v1->ticket[1],
+                      v1->ticket[2], v1->ticket[3],
+                      v1->ticket[4], v1->ticket[5],
+                      v1->ticket[6], v1->ticket[7]);
 
        ret = -EPROTONOSUPPORT;
-       if (tsec->security_index != RXRPC_SECURITY_RXKAD)
+       if (v1->security_index != RXRPC_SECURITY_RXKAD)
                goto error;
 
-       key->type_data.x[0] = tsec->security_index;
-
-       plen = sizeof(*upayload) + tsec->ticket_len;
-       ret = key_payload_reserve(key, plen);
+       plen = sizeof(*token->kad) + v1->ticket_length;
+       ret = key_payload_reserve(key, plen + sizeof(*token));
        if (ret < 0)
                goto error;
 
        ret = -ENOMEM;
-       upayload = kmalloc(plen, GFP_KERNEL);
-       if (!upayload)
+       token = kmalloc(sizeof(*token), GFP_KERNEL);
+       if (!token)
                goto error;
+       token->kad = kmalloc(plen, GFP_KERNEL);
+       if (!token->kad)
+               goto error_free;
+
+       token->security_index           = RXRPC_SECURITY_RXKAD;
+       token->kad->ticket_len          = v1->ticket_length;
+       token->kad->expiry              = v1->expiry;
+       token->kad->kvno                = v1->kvno;
+       memcpy(&token->kad->session_key, &v1->session_key, 8);
+       memcpy(&token->kad->ticket, v1->ticket, v1->ticket_length);
 
        /* attach the data */
-       memcpy(&upayload->k, tsec, sizeof(*tsec));
-       memcpy(&upayload->k.ticket, (void *)tsec + sizeof(*tsec),
-              tsec->ticket_len);
-       key->payload.data = upayload;
-       key->expiry = tsec->expiry;
+       key->type_data.x[0]++;
+
+       pp = (struct rxrpc_key_token **)&key->payload.data;
+       while (*pp)
+               pp = &(*pp)->next;
+       *pp = token;
+       if (token->kad->expiry < key->expiry)
+               key->expiry = token->kad->expiry;
+       token = NULL;
        ret = 0;
 
+error_free:
+       kfree(token);
 error:
        return ret;
 }
@@ -184,7 +402,22 @@ static int rxrpc_instantiate_s(struct key *key, const void *data,
  */
 static void rxrpc_destroy(struct key *key)
 {
-       kfree(key->payload.data);
+       struct rxrpc_key_token *token;
+
+       while ((token = key->payload.data)) {
+               key->payload.data = token->next;
+               switch (token->security_index) {
+               case RXRPC_SECURITY_RXKAD:
+                       kfree(token->kad);
+                       break;
+               default:
+                       printk(KERN_ERR "Unknown token type %x on rxrpc key\n",
+                              token->security_index);
+                       BUG();
+               }
+
+               kfree(token);
+       }
 }
 
 /*
@@ -293,7 +526,7 @@ int rxrpc_get_server_data_key(struct rxrpc_connection *conn,
 
        struct {
                u32 kver;
-               struct rxkad_key tsec;
+               struct rxrpc_key_data_v1 v1;
        } data;
 
        _enter("");
@@ -308,13 +541,12 @@ int rxrpc_get_server_data_key(struct rxrpc_connection *conn,
        _debug("key %d", key_serial(key));
 
        data.kver = 1;
-       data.tsec.security_index = RXRPC_SECURITY_RXKAD;
-       data.tsec.ticket_len = 0;
-       data.tsec.expiry = expiry;
-       data.tsec.kvno = 0;
+       data.v1.security_index = RXRPC_SECURITY_RXKAD;
+       data.v1.ticket_length = 0;
+       data.v1.expiry = expiry;
+       data.v1.kvno = 0;
 
-       memcpy(&data.tsec.session_key, session_key,
-              sizeof(data.tsec.session_key));
+       memcpy(&data.v1.session_key, session_key, sizeof(data.v1.session_key));
 
        ret = key_instantiate_and_link(key, &data, sizeof(data), NULL, NULL);
        if (ret < 0)

diff --git a/net/rxrpc/ar-security.c b/net/rxrpc/ar-security.c
index dc62920..49b3cc3 100644 (file)
--- a/net/rxrpc/ar-security.c
+++ b/net/rxrpc/ar-security.c
@@ -16,6 +16,7 @@
 #include <linux/crypto.h>
 #include <net/sock.h>
 #include <net/af_rxrpc.h>
+#include <keys/rxrpc-type.h>
 #include "ar-internal.h"
 
 static LIST_HEAD(rxrpc_security_methods);
@@ -122,6 +123,7 @@ EXPORT_SYMBOL_GPL(rxrpc_unregister_security);
  */
 int rxrpc_init_client_conn_security(struct rxrpc_connection *conn)
 {
+       struct rxrpc_key_token *token;
        struct rxrpc_security *sec;
        struct key *key = conn->key;
        int ret;
@@ -135,7 +137,11 @@ int rxrpc_init_client_conn_security(struct rxrpc_connection *conn)
        if (ret < 0)
                return ret;
 
-       sec = rxrpc_security_lookup(key->type_data.x[0]);
+       if (!key->payload.data)
+               return -EKEYREJECTED;
+       token = key->payload.data;
+
+       sec = rxrpc_security_lookup(token->security_index);
        if (!sec)
                return -EKEYREJECTED;
        conn->security = sec;

diff --git a/net/rxrpc/rxkad.c b/net/rxrpc/rxkad.c
index acec762..713ac59 100644 (file)
--- a/net/rxrpc/rxkad.c
+++ b/net/rxrpc/rxkad.c
@@ -18,6 +18,7 @@
 #include <linux/ctype.h>
 #include <net/sock.h>
 #include <net/af_rxrpc.h>
+#include <keys/rxrpc-type.h>
 #define rxrpc_debug rxkad_debug
 #include "ar-internal.h"
 
@@ -59,14 +60,14 @@ static DEFINE_MUTEX(rxkad_ci_mutex);
  */
 static int rxkad_init_connection_security(struct rxrpc_connection *conn)
 {
-       struct rxrpc_key_payload *payload;
        struct crypto_blkcipher *ci;
+       struct rxrpc_key_token *token;
        int ret;
 
        _enter("{%d},{%x}", conn->debug_id, key_serial(conn->key));
 
-       payload = conn->key->payload.data;
-       conn->security_ix = payload->k.security_index;
+       token = conn->key->payload.data;
+       conn->security_ix = token->security_index;
 
        ci = crypto_alloc_blkcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC);
        if (IS_ERR(ci)) {
@@ -75,8 +76,8 @@ static int rxkad_init_connection_security(struct rxrpc_connection *conn)
                goto error;
        }
 
-       if (crypto_blkcipher_setkey(ci, payload->k.session_key,
-                                   sizeof(payload->k.session_key)) < 0)
+       if (crypto_blkcipher_setkey(ci, token->kad->session_key,
+                                   sizeof(token->kad->session_key)) < 0)
                BUG();
 
        switch (conn->security_level) {
@@ -110,7 +111,7 @@ error:
  */
 static void rxkad_prime_packet_security(struct rxrpc_connection *conn)
 {
-       struct rxrpc_key_payload *payload;
+       struct rxrpc_key_token *token;
        struct blkcipher_desc desc;
        struct scatterlist sg[2];
        struct rxrpc_crypt iv;
@@ -123,8 +124,8 @@ static void rxkad_prime_packet_security(struct rxrpc_connection *conn)
        if (!conn->key)
                return;
 
-       payload = conn->key->payload.data;
-       memcpy(&iv, payload->k.session_key, sizeof(iv));
+       token = conn->key->payload.data;
+       memcpy(&iv, token->kad->session_key, sizeof(iv));
 
        desc.tfm = conn->cipher;
        desc.info = iv.x;
@@ -197,7 +198,7 @@ static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call,
                                        u32 data_size,
                                        void *sechdr)
 {
-       const struct rxrpc_key_payload *payload;
+       const struct rxrpc_key_token *token;
        struct rxkad_level2_hdr rxkhdr
                __attribute__((aligned(8))); /* must be all on one page */
        struct rxrpc_skb_priv *sp;
@@ -219,8 +220,8 @@ static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call,
        rxkhdr.checksum = 0;
 
        /* encrypt from the session key */
-       payload = call->conn->key->payload.data;
-       memcpy(&iv, payload->k.session_key, sizeof(iv));
+       token = call->conn->key->payload.data;
+       memcpy(&iv, token->kad->session_key, sizeof(iv));
        desc.tfm = call->conn->cipher;
        desc.info = iv.x;
        desc.flags = 0;
@@ -400,7 +401,7 @@ static int rxkad_verify_packet_encrypt(const struct rxrpc_call *call,
                                       struct sk_buff *skb,
                                       u32 *_abort_code)
 {
-       const struct rxrpc_key_payload *payload;
+       const struct rxrpc_key_token *token;
        struct rxkad_level2_hdr sechdr;
        struct rxrpc_skb_priv *sp;
        struct blkcipher_desc desc;
@@ -431,8 +432,8 @@ static int rxkad_verify_packet_encrypt(const struct rxrpc_call *call,
        skb_to_sgvec(skb, sg, 0, skb->len);
 
        /* decrypt from the session key */
-       payload = call->conn->key->payload.data;
-       memcpy(&iv, payload->k.session_key, sizeof(iv));
+       token = call->conn->key->payload.data;
+       memcpy(&iv, token->kad->session_key, sizeof(iv));
        desc.tfm = call->conn->cipher;
        desc.info = iv.x;
        desc.flags = 0;
@@ -737,7 +738,7 @@ static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
                                      struct sk_buff *skb,
                                      u32 *_abort_code)
 {
-       const struct rxrpc_key_payload *payload;
+       const struct rxrpc_key_token *token;
        struct rxkad_challenge challenge;
        struct rxkad_response resp
                __attribute__((aligned(8))); /* must be aligned for crypto */
@@ -778,7 +779,7 @@ static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
        if (conn->security_level < min_level)
                goto protocol_error;
 
-       payload = conn->key->payload.data;
+       token = conn->key->payload.data;
 
        /* build the response packet */
        memset(&resp, 0, sizeof(resp));
@@ -797,13 +798,13 @@ static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
                (conn->channels[3] ? conn->channels[3]->call_id : 0);
        resp.encrypted.inc_nonce = htonl(nonce + 1);
        resp.encrypted.level = htonl(conn->security_level);
-       resp.kvno = htonl(payload->k.kvno);
-       resp.ticket_len = htonl(payload->k.ticket_len);
+       resp.kvno = htonl(token->kad->kvno);
+       resp.ticket_len = htonl(token->kad->ticket_len);
 
        /* calculate the response checksum and then do the encryption */
        rxkad_calc_response_checksum(&resp);
-       rxkad_encrypt_response(conn, &resp, &payload->k);
-       return rxkad_send_response(conn, &sp->hdr, &resp, &payload->k);
+       rxkad_encrypt_response(conn, &resp, token->kad);
+       return rxkad_send_response(conn, &sp->hdr, &resp, token->kad);
 
 protocol_error:
        *_abort_code = abort_code;