/* RxRPC key management
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * 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; either version
 * 2 of the License, or (at your option) any later version.
 *
 * RxRPC keys should have a description of describing their purpose:
 *      "afs@CAMBRIDGE.REDHAT.COM>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <crypto/skcipher.h>
#include <linux/module.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/key-type.h>
#include <linux/ctype.h>
#include <linux/slab.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include <keys/rxrpc-type.h>
#include <keys/user-type.h>
#include "ar-internal.h"

static int rxrpc_vet_description_s(const char *);
static int rxrpc_preparse(struct key_preparsed_payload *);
static int rxrpc_preparse_s(struct key_preparsed_payload *);
static void rxrpc_free_preparse(struct key_preparsed_payload *);
static void rxrpc_free_preparse_s(struct key_preparsed_payload *);
static void rxrpc_destroy(struct key *);
static void rxrpc_destroy_s(struct key *);
static void rxrpc_describe(const struct key *, struct seq_file *);
static long rxrpc_read(const struct key *, char *, size_t);

/*
 * rxrpc defined keys take an arbitrary string as the description and an
 * arbitrary blob of data as the payload
 */
struct key_type key_type_rxrpc = {
        .name           = "rxrpc",
        .preparse       = rxrpc_preparse,
        .free_preparse  = rxrpc_free_preparse,
        .instantiate    = generic_key_instantiate,
        .destroy        = rxrpc_destroy,
        .describe       = rxrpc_describe,
        .read           = rxrpc_read,
};
EXPORT_SYMBOL(key_type_rxrpc);

/*
 * rxrpc server defined keys take "<serviceId>:<securityIndex>" as the
 * description and an 8-byte decryption key as the payload
 */
struct key_type key_type_rxrpc_s = {
        .name           = "rxrpc_s",
        .vet_description = rxrpc_vet_description_s,
        .preparse       = rxrpc_preparse_s,
        .free_preparse  = rxrpc_free_preparse_s,
        .instantiate    = generic_key_instantiate,
        .destroy        = rxrpc_destroy_s,
        .describe       = rxrpc_describe,
};

/*
 * Vet the description for an RxRPC server key
 */
static int rxrpc_vet_description_s(const char *desc)
{
        unsigned long num;
        char *p;

        num = simple_strtoul(desc, &p, 10);
        if (*p != ':' || num > 65535)
                return -EINVAL;
        num = simple_strtoul(p + 1, &p, 10);
        if (*p || num < 1 || num > 255)
                return -EINVAL;
        return 0;
}

/*
 * parse an RxKAD type XDR format token
 * - the caller guarantees we have at least 4 words
 */
static int rxrpc_preparse_xdr_rxkad(struct key_preparsed_payload *prep,
                                    size_t datalen,
                                    const __be32 *xdr, unsigned int toklen)
{
        struct rxrpc_key_token *token, **pptoken;
        time64_t expiry;
        size_t plen;
        u32 tktlen;

        _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 (toklen < 8 * 4 + tktlen)
                return -EKEYREJECTED;

        plen = sizeof(*token) + sizeof(*token->kad) + tktlen;
        prep->quotalen = datalen + plen;

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

        token->kad = kzalloc(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 */
        prep->payload.data[1] = (void *)((unsigned long)prep->payload.data[1] + 1);

        /* attach the data */
        for (pptoken = (struct rxrpc_key_token **)&prep->payload.data[0];
             *pptoken;
             pptoken = &(*pptoken)->next)
                continue;
        *pptoken = token;
        expiry = rxrpc_u32_to_time64(token->kad->expiry);
        if (expiry < prep->expiry)
                prep->expiry = expiry;

        _leave(" = 0");
        return 0;
}

static void rxrpc_free_krb5_principal(struct krb5_principal *princ)
{
        int loop;

        if (princ->name_parts) {
                for (loop = princ->n_name_parts - 1; loop >= 0; loop--)
                        kfree(princ->name_parts[loop]);
                kfree(princ->name_parts);
        }
        kfree(princ->realm);
}

static void rxrpc_free_krb5_tagged(struct krb5_tagged_data *td)
{
        kfree(td->data);
}

/*
 * free up an RxK5 token
 */
static void rxrpc_rxk5_free(struct rxk5_key *rxk5)
{
        int loop;

        rxrpc_free_krb5_principal(&rxk5->client);
        rxrpc_free_krb5_principal(&rxk5->server);
        rxrpc_free_krb5_tagged(&rxk5->session);

        if (rxk5->addresses) {
                for (loop = rxk5->n_addresses - 1; loop >= 0; loop--)
                        rxrpc_free_krb5_tagged(&rxk5->addresses[loop]);
                kfree(rxk5->addresses);
        }
        if (rxk5->authdata) {
                for (loop = rxk5->n_authdata - 1; loop >= 0; loop--)
                        rxrpc_free_krb5_tagged(&rxk5->authdata[loop]);
                kfree(rxk5->authdata);
        }

        kfree(rxk5->ticket);
        kfree(rxk5->ticket2);
        kfree(rxk5);
}

/*
 * extract a krb5 principal
 */
static int rxrpc_krb5_decode_principal(struct krb5_principal *princ,
                                       const __be32 **_xdr,
                                       unsigned int *_toklen)
{
        const __be32 *xdr = *_xdr;
        unsigned int toklen = *_toklen, n_parts, loop, tmp, paddedlen;

        /* there must be at least one name, and at least #names+1 length
         * words */
        if (toklen <= 12)
                return -EINVAL;

        _enter(",{%x,%x,%x},%u",
               ntohl(xdr[0]), ntohl(xdr[1]), ntohl(xdr[2]), toklen);

        n_parts = ntohl(*xdr++);
        toklen -= 4;
        if (n_parts <= 0 || n_parts > AFSTOKEN_K5_COMPONENTS_MAX)
                return -EINVAL;
        princ->n_name_parts = n_parts;

        if (toklen <= (n_parts + 1) * 4)
                return -EINVAL;

        princ->name_parts = kcalloc(n_parts, sizeof(char *), GFP_KERNEL);
        if (!princ->name_parts)
                return -ENOMEM;

        for (loop = 0; loop < n_parts; loop++) {
                if (toklen < 4)
                        return -EINVAL;
                tmp = ntohl(*xdr++);
                toklen -= 4;
                if (tmp <= 0 || tmp > AFSTOKEN_STRING_MAX)
                        return -EINVAL;
                paddedlen = (tmp + 3) & ~3;
                if (paddedlen > toklen)
                        return -EINVAL;
                princ->name_parts[loop] = kmalloc(tmp + 1, GFP_KERNEL);
                if (!princ->name_parts[loop])
                        return -ENOMEM;
                memcpy(princ->name_parts[loop], xdr, tmp);
                princ->name_parts[loop][tmp] = 0;
                toklen -= paddedlen;
                xdr += paddedlen >> 2;
        }

        if (toklen < 4)
                return -EINVAL;
        tmp = ntohl(*xdr++);
        toklen -= 4;
        if (tmp <= 0 || tmp > AFSTOKEN_K5_REALM_MAX)
                return -EINVAL;
        paddedlen = (tmp + 3) & ~3;
        if (paddedlen > toklen)
                return -EINVAL;
        princ->realm = kmalloc(tmp + 1, GFP_KERNEL);
        if (!princ->realm)
                return -ENOMEM;
        memcpy(princ->realm, xdr, tmp);
        princ->realm[tmp] = 0;
        toklen -= paddedlen;
        xdr += paddedlen >> 2;

        _debug("%s/...@%s", princ->name_parts[0], princ->realm);

        *_xdr = xdr;
        *_toklen = toklen;
        _leave(" = 0 [toklen=%u]", toklen);
        return 0;
}

/*
 * extract a piece of krb5 tagged data
 */
static int rxrpc_krb5_decode_tagged_data(struct krb5_tagged_data *td,
                                         size_t max_data_size,
                                         const __be32 **_xdr,
                                         unsigned int *_toklen)
{
        const __be32 *xdr = *_xdr;
        unsigned int toklen = *_toklen, len, paddedlen;

        /* there must be at least one tag and one length word */
        if (toklen <= 8)
                return -EINVAL;

        _enter(",%zu,{%x,%x},%u",
               max_data_size, ntohl(xdr[0]), ntohl(xdr[1]), toklen);

        td->tag = ntohl(*xdr++);
        len = ntohl(*xdr++);
        toklen -= 8;
        if (len > max_data_size)
                return -EINVAL;
        paddedlen = (len + 3) & ~3;
        if (paddedlen > toklen)
                return -EINVAL;
        td->data_len = len;

        if (len > 0) {
                td->data = kmemdup(xdr, len, GFP_KERNEL);
                if (!td->data)
                        return -ENOMEM;
                toklen -= paddedlen;
                xdr += paddedlen >> 2;
        }

        _debug("tag %x len %x", td->tag, td->data_len);

        *_xdr = xdr;
        *_toklen = toklen;
        _leave(" = 0 [toklen=%u]", toklen);
        return 0;
}

/*
 * extract an array of tagged data
 */
static int rxrpc_krb5_decode_tagged_array(struct krb5_tagged_data **_td,
                                          u8 *_n_elem,
                                          u8 max_n_elem,
                                          size_t max_elem_size,
                                          const __be32 **_xdr,
                                          unsigned int *_toklen)
{
        struct krb5_tagged_data *td;
        const __be32 *xdr = *_xdr;
        unsigned int toklen = *_toklen, n_elem, loop;
        int ret;

        /* there must be at least one count */
        if (toklen < 4)
                return -EINVAL;

        _enter(",,%u,%zu,{%x},%u",
               max_n_elem, max_elem_size, ntohl(xdr[0]), toklen);

        n_elem = ntohl(*xdr++);
        toklen -= 4;
        if (n_elem > max_n_elem)
                return -EINVAL;
        *_n_elem = n_elem;
        if (n_elem > 0) {
                if (toklen <= (n_elem + 1) * 4)
                        return -EINVAL;

                _debug("n_elem %d", n_elem);

                td = kcalloc(n_elem, sizeof(struct krb5_tagged_data),
                             GFP_KERNEL);
                if (!td)
                        return -ENOMEM;
                *_td = td;

                for (loop = 0; loop < n_elem; loop++) {
                        ret = rxrpc_krb5_decode_tagged_data(&td[loop],
                                                            max_elem_size,
                                                            &xdr, &toklen);
                        if (ret < 0)
                                return ret;
                }
        }

        *_xdr = xdr;
        *_toklen = toklen;
        _leave(" = 0 [toklen=%u]", toklen);
        return 0;
}

/*
 * extract a krb5 ticket
 */
static int rxrpc_krb5_decode_ticket(u8 **_ticket, u16 *_tktlen,
                                    const __be32 **_xdr, unsigned int *_toklen)
{
        const __be32 *xdr = *_xdr;
        unsigned int toklen = *_toklen, len, paddedlen;

        /* there must be at least one length word */
        if (toklen <= 4)
                return -EINVAL;

        _enter(",{%x},%u", ntohl(xdr[0]), toklen);

        len = ntohl(*xdr++);
        toklen -= 4;
        if (len > AFSTOKEN_K5_TIX_MAX)
                return -EINVAL;
        paddedlen = (len + 3) & ~3;
        if (paddedlen > toklen)
                return -EINVAL;
        *_tktlen = len;

        _debug("ticket len %u", len);

        if (len > 0) {
                *_ticket = kmemdup(xdr, len, GFP_KERNEL);
                if (!*_ticket)
                        return -ENOMEM;
                toklen -= paddedlen;
                xdr += paddedlen >> 2;
        }

        *_xdr = xdr;
        *_toklen = toklen;
        _leave(" = 0 [toklen=%u]", toklen);
        return 0;
}

/*
 * parse an RxK5 type XDR format token
 * - the caller guarantees we have at least 4 words
 */
static int rxrpc_preparse_xdr_rxk5(struct key_preparsed_payload *prep,
                                   size_t datalen,
                                   const __be32 *xdr, unsigned int toklen)
{
        struct rxrpc_key_token *token, **pptoken;
        struct rxk5_key *rxk5;
        const __be32 *end_xdr = xdr + (toklen >> 2);
        time64_t expiry;
        int ret;

        _enter(",{%x,%x,%x,%x},%u",
               ntohl(xdr[0]), ntohl(xdr[1]), ntohl(xdr[2]), ntohl(xdr[3]),
               toklen);

        /* reserve some payload space for this subkey - the length of the token
         * is a reasonable approximation */
        prep->quotalen = datalen + toklen;

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

        rxk5 = kzalloc(sizeof(*rxk5), GFP_KERNEL);
        if (!rxk5) {
                kfree(token);
                return -ENOMEM;
        }

        token->security_index = RXRPC_SECURITY_RXK5;
        token->k5 = rxk5;

        /* extract the principals */
        ret = rxrpc_krb5_decode_principal(&rxk5->client, &xdr, &toklen);
        if (ret < 0)
                goto error;
        ret = rxrpc_krb5_decode_principal(&rxk5->server, &xdr, &toklen);
        if (ret < 0)
                goto error;

        /* extract the session key and the encoding type (the tag field ->
         * ENCTYPE_xxx) */
        ret = rxrpc_krb5_decode_tagged_data(&rxk5->session, AFSTOKEN_DATA_MAX,
                                            &xdr, &toklen);
        if (ret < 0)
                goto error;

        if (toklen < 4 * 8 + 2 * 4)
                goto inval;
        rxk5->authtime  = be64_to_cpup((const __be64 *) xdr);
        xdr += 2;
        rxk5->starttime = be64_to_cpup((const __be64 *) xdr);
        xdr += 2;
        rxk5->endtime   = be64_to_cpup((const __be64 *) xdr);
        xdr += 2;
        rxk5->renew_till = be64_to_cpup((const __be64 *) xdr);
        xdr += 2;
        rxk5->is_skey = ntohl(*xdr++);
        rxk5->flags = ntohl(*xdr++);
        toklen -= 4 * 8 + 2 * 4;

        _debug("times: a=%llx s=%llx e=%llx rt=%llx",
               rxk5->authtime, rxk5->starttime, rxk5->endtime,
               rxk5->renew_till);
        _debug("is_skey=%x flags=%x", rxk5->is_skey, rxk5->flags);

        /* extract the permitted client addresses */
        ret = rxrpc_krb5_decode_tagged_array(&rxk5->addresses,
                                             &rxk5->n_addresses,
                                             AFSTOKEN_K5_ADDRESSES_MAX,
                                             AFSTOKEN_DATA_MAX,
                                             &xdr, &toklen);
        if (ret < 0)
                goto error;

        ASSERTCMP((end_xdr - xdr) << 2, ==, toklen);

        /* extract the tickets */
        ret = rxrpc_krb5_decode_ticket(&rxk5->ticket, &rxk5->ticket_len,
                                       &xdr, &toklen);
        if (ret < 0)
                goto error;
        ret = rxrpc_krb5_decode_ticket(&rxk5->ticket2, &rxk5->ticket2_len,
                                       &xdr, &toklen);
        if (ret < 0)
                goto error;

        ASSERTCMP((end_xdr - xdr) << 2, ==, toklen);

        /* extract the typed auth data */
        ret = rxrpc_krb5_decode_tagged_array(&rxk5->authdata,
                                             &rxk5->n_authdata,
                                             AFSTOKEN_K5_AUTHDATA_MAX,
                                             AFSTOKEN_BDATALN_MAX,
                                             &xdr, &toklen);
        if (ret < 0)
                goto error;

        ASSERTCMP((end_xdr - xdr) << 2, ==, toklen);

        if (toklen != 0)
                goto inval;

        /* attach the payload */
        for (pptoken = (struct rxrpc_key_token **)&prep->payload.data[0];
             *pptoken;
             pptoken = &(*pptoken)->next)
                continue;
        *pptoken = token;
        expiry = rxrpc_u32_to_time64(token->k5->endtime);
        if (expiry < prep->expiry)
                prep->expiry = expiry;

        _leave(" = 0");
        return 0;

inval:
        ret = -EINVAL;
error:
        rxrpc_rxk5_free(rxk5);
        kfree(token);
        _leave(" = %d", ret);
        return ret;
}

/*
 * attempt to parse the data as the XDR format
 * - the caller guarantees we have more than 7 words
 */
static int rxrpc_preparse_xdr(struct key_preparsed_payload *prep)
{
        const __be32 *xdr = prep->data, *token;
        const char *cp;
        unsigned int len, paddedlen, loop, ntoken, toklen, sec_ix;
        size_t datalen = prep->datalen;
        int ret;

        _enter(",{%x,%x,%x,%x},%zu",
               ntohl(xdr[0]), ntohl(xdr[1]), ntohl(xdr[2]), ntohl(xdr[3]),
               prep->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;
        paddedlen = (len + 3) & ~3;
        if (paddedlen > datalen)
                goto not_xdr;

        cp = (const char *) xdr;
        for (loop = 0; loop < len; loop++)
                if (!isprint(cp[loop]))
                        goto not_xdr;
        for (; loop < paddedlen; loop++)
                if (cp[loop])
                        goto not_xdr;
        _debug("cellname: [%u/%u] '%*.*s'",
               len, paddedlen, len, len, (const char *) xdr);
        datalen -= paddedlen;
        xdr += paddedlen >> 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);
                paddedlen = (toklen + 3) & ~3;
                if (toklen < 20 || toklen > datalen || paddedlen > datalen)
                        goto not_xdr;
                datalen -= paddedlen;
                xdr += paddedlen >> 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;

                _debug("TOKEN type=%u [%p-%p]", sec_ix, xdr, token);

                switch (sec_ix) {
                case RXRPC_SECURITY_RXKAD:
                        ret = rxrpc_preparse_xdr_rxkad(prep, datalen, xdr, toklen);
                        if (ret != 0)
                                goto error;
                        break;

                case RXRPC_SECURITY_RXK5:
                        ret = rxrpc_preparse_xdr_rxk5(prep, datalen, 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;
}

/*
 * Preparse an rxrpc defined key.
 *
 * Data should be of the form:
 *      OFFSET  LEN     CONTENT
 *      0       4       key interface version number
 *      4       2       security index (type)
 *      6       2       ticket length
 *      8       4       key expiry time (time_t)
 *      12      4       kvno
 *      16      8       session key
 *      24      [len]   ticket
 *
 * if no data is provided, then a no-security key is made
 */
static int rxrpc_preparse(struct key_preparsed_payload *prep)
{
        const struct rxrpc_key_data_v1 *v1;
        struct rxrpc_key_token *token, **pp;
        time64_t expiry;
        size_t plen;
        u32 kver;
        int ret;

        _enter("%zu", prep->datalen);

        /* handle a no-security key */
        if (!prep->data && prep->datalen == 0)
                return 0;

        /* determine if the XDR payload format is being used */
        if (prep->datalen > 7 * 4) {
                ret = rxrpc_preparse_xdr(prep);
                if (ret != -EPROTO)
                        return ret;
        }

        /* get the key interface version number */
        ret = -EINVAL;
        if (prep->datalen <= 4 || !prep->data)
                goto error;
        memcpy(&kver, prep->data, sizeof(kver));
        prep->data += sizeof(kver);
        prep->datalen -= sizeof(kver);

        _debug("KEY I/F VERSION: %u", kver);

        ret = -EKEYREJECTED;
        if (kver != 1)
                goto error;

        /* deal with a version 1 key */
        ret = -EINVAL;
        if (prep->datalen < sizeof(*v1))
                goto error;

        v1 = prep->data;
        if (prep->datalen != sizeof(*v1) + v1->ticket_length)
                goto error;

        _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",
               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",
                       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 (v1->security_index != RXRPC_SECURITY_RXKAD)
                goto error;

        plen = sizeof(*token->kad) + v1->ticket_length;
        prep->quotalen = plen + sizeof(*token);

        ret = -ENOMEM;
        token = kzalloc(sizeof(*token), GFP_KERNEL);
        if (!token)
                goto error;
        token->kad = kzalloc(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);

        /* count the number of tokens attached */
        prep->payload.data[1] = (void *)((unsigned long)prep->payload.data[1] + 1);

        /* attach the data */
        pp = (struct rxrpc_key_token **)&prep->payload.data[0];
        while (*pp)
                pp = &(*pp)->next;
        *pp = token;
        expiry = rxrpc_u32_to_time64(token->kad->expiry);
        if (expiry < prep->expiry)
                prep->expiry = expiry;
        token = NULL;
        ret = 0;

error_free:
        kfree(token);
error:
        return ret;
}

/*
 * Free token list.
 */
static void rxrpc_free_token_list(struct rxrpc_key_token *token)
{
        struct rxrpc_key_token *next;

        for (; token; token = next) {
                next = token->next;
                switch (token->security_index) {
                case RXRPC_SECURITY_RXKAD:
                        kfree(token->kad);
                        break;
                case RXRPC_SECURITY_RXK5:
                        if (token->k5)
                                rxrpc_rxk5_free(token->k5);
                        break;
                default:
                        pr_err("Unknown token type %x on rxrpc key\n",
                               token->security_index);
                        BUG();
                }

                kfree(token);
        }
}

/*
 * Clean up preparse data.
 */
static void rxrpc_free_preparse(struct key_preparsed_payload *prep)
{
        rxrpc_free_token_list(prep->payload.data[0]);
}

/*
 * Preparse a server secret key.
 *
 * The data should be the 8-byte secret key.
 */
static int rxrpc_preparse_s(struct key_preparsed_payload *prep)
{
        struct crypto_skcipher *ci;

        _enter("%zu", prep->datalen);

        if (prep->datalen != 8)
                return -EINVAL;

        memcpy(&prep->payload.data[2], prep->data, 8);

        ci = crypto_alloc_skcipher("pcbc(des)", 0, CRYPTO_ALG_ASYNC);
        if (IS_ERR(ci)) {
                _leave(" = %ld", PTR_ERR(ci));
                return PTR_ERR(ci);
        }

        if (crypto_skcipher_setkey(ci, prep->data, 8) < 0)
                BUG();

        prep->payload.data[0] = ci;
        _leave(" = 0");
        return 0;
}

/*
 * Clean up preparse data.
 */
static void rxrpc_free_preparse_s(struct key_preparsed_payload *prep)
{
        if (prep->payload.data[0])
                crypto_free_skcipher(prep->payload.data[0]);
}

/*
 * dispose of the data dangling from the corpse of a rxrpc key
 */
static void rxrpc_destroy(struct key *key)
{
        rxrpc_free_token_list(key->payload.data[0]);
}

/*
 * dispose of the data dangling from the corpse of a rxrpc key
 */
static void rxrpc_destroy_s(struct key *key)
{
        if (key->payload.data[0]) {
                crypto_free_skcipher(key->payload.data[0]);
                key->payload.data[0] = NULL;
        }
}

/*
 * describe the rxrpc key
 */
static void rxrpc_describe(const struct key *key, struct seq_file *m)
{
        seq_puts(m, key->description);
}

/*
 * grab the security key for a socket
 */
int rxrpc_request_key(struct rxrpc_sock *rx, char __user *optval, int optlen)
{
        struct key *key;
        char *description;

        _enter("");

        if (optlen <= 0 || optlen > PAGE_SIZE - 1)
                return -EINVAL;

        description = memdup_user_nul(optval, optlen);
        if (IS_ERR(description))
                return PTR_ERR(description);

        key = request_key(&key_type_rxrpc, description, NULL);
        if (IS_ERR(key)) {
                kfree(description);
                _leave(" = %ld", PTR_ERR(key));
                return PTR_ERR(key);
        }

        rx->key = key;
        kfree(description);
        _leave(" = 0 [key %x]", key->serial);
        return 0;
}

/*
 * grab the security keyring for a server socket
 */
int rxrpc_server_keyring(struct rxrpc_sock *rx, char __user *optval,
                         int optlen)
{
        struct key *key;
        char *description;

        _enter("");

        if (optlen <= 0 || optlen > PAGE_SIZE - 1)
                return -EINVAL;

        description = memdup_user_nul(optval, optlen);
        if (IS_ERR(description))
                return PTR_ERR(description);

        key = request_key(&key_type_keyring, description, NULL);
        if (IS_ERR(key)) {
                kfree(description);
                _leave(" = %ld", PTR_ERR(key));
                return PTR_ERR(key);
        }

        rx->securities = key;
        kfree(description);
        _leave(" = 0 [key %x]", key->serial);
        return 0;
}

/*
 * generate a server data key
 */
int rxrpc_get_server_data_key(struct rxrpc_connection *conn,
                              const void *session_key,
                              time64_t expiry,
                              u32 kvno)
{
        const struct cred *cred = current_cred();
        struct key *key;
        int ret;

        struct {
                u32 kver;
                struct rxrpc_key_data_v1 v1;
        } data;

        _enter("");

        key = key_alloc(&key_type_rxrpc, "x",
                        GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred, 0,
                        KEY_ALLOC_NOT_IN_QUOTA, NULL);
        if (IS_ERR(key)) {
                _leave(" = -ENOMEM [alloc %ld]", PTR_ERR(key));
                return -ENOMEM;
        }

        _debug("key %d", key_serial(key));

        data.kver = 1;
        data.v1.security_index = RXRPC_SECURITY_RXKAD;
        data.v1.ticket_length = 0;
        data.v1.expiry = rxrpc_time64_to_u32(expiry);
        data.v1.kvno = 0;

        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)
                goto error;

        conn->params.key = key;

        _leave(" = 0 [%d]", key_serial(key));
        return 0;

error:
        key_revoke(key);
        key_put(key);
        _leave(" = -ENOMEM [ins %d]", ret);
        return -ENOMEM;
}
EXPORT_SYMBOL(rxrpc_get_server_data_key);

/**
 * rxrpc_get_null_key - Generate a null RxRPC key
 * @keyname: The name to give the key.
 *
 * Generate a null RxRPC key that can be used to indicate anonymous security is
 * required for a particular domain.
 */
struct key *rxrpc_get_null_key(const char *keyname)
{
        const struct cred *cred = current_cred();
        struct key *key;
        int ret;

        key = key_alloc(&key_type_rxrpc, keyname,
                        GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred,
                        KEY_POS_SEARCH, KEY_ALLOC_NOT_IN_QUOTA, NULL);
        if (IS_ERR(key))
                return key;

        ret = key_instantiate_and_link(key, NULL, 0, NULL, NULL);
        if (ret < 0) {
                key_revoke(key);
                key_put(key);
                return ERR_PTR(ret);
        }

        return key;
}
EXPORT_SYMBOL(rxrpc_get_null_key);

/*
 * read the contents of an rxrpc key
 * - this returns the result in XDR form
 */
static long rxrpc_read(const struct key *key,
                       char *buffer, size_t buflen)
{
        const struct rxrpc_key_token *token;
        const struct krb5_principal *princ;
        size_t size;
        __be32 *xdr, *oldxdr;
        u32 cnlen, toksize, ntoks, tok, zero;
        u16 toksizes[AFSTOKEN_MAX];
        int loop;

        _enter("");

        /* we don't know what form we should return non-AFS keys in */
        if (memcmp(key->description, "afs@", 4) != 0)
                return -EOPNOTSUPP;
        cnlen = strlen(key->description + 4);

#define RND(X) (((X) + 3) & ~3)

        /* AFS keys we return in XDR form, so we need to work out the size of
         * the XDR */
        size = 2 * 4;   /* flags, cellname len */
        size += RND(cnlen);     /* cellname */
        size += 1 * 4;  /* token count */

        ntoks = 0;
        for (token = key->payload.data[0]; token; token = token->next) {
                toksize = 4;    /* sec index */

                switch (token->security_index) {
                case RXRPC_SECURITY_RXKAD:
                        toksize += 9 * 4;       /* viceid, kvno, key*2 + len, begin,
                                                 * end, primary, tktlen */
                        toksize += RND(token->kad->ticket_len);
                        break;

                case RXRPC_SECURITY_RXK5:
                        princ = &token->k5->client;
                        toksize += 4 + princ->n_name_parts * 4;
                        for (loop = 0; loop < princ->n_name_parts; loop++)
                                toksize += RND(strlen(princ->name_parts[loop]));
                        toksize += 4 + RND(strlen(princ->realm));

                        princ = &token->k5->server;
                        toksize += 4 + princ->n_name_parts * 4;
                        for (loop = 0; loop < princ->n_name_parts; loop++)
                                toksize += RND(strlen(princ->name_parts[loop]));
                        toksize += 4 + RND(strlen(princ->realm));

                        toksize += 8 + RND(token->k5->session.data_len);

                        toksize += 4 * 8 + 2 * 4;

                        toksize += 4 + token->k5->n_addresses * 8;
                        for (loop = 0; loop < token->k5->n_addresses; loop++)
                                toksize += RND(token->k5->addresses[loop].data_len);

                        toksize += 4 + RND(token->k5->ticket_len);
                        toksize += 4 + RND(token->k5->ticket2_len);

                        toksize += 4 + token->k5->n_authdata * 8;
                        for (loop = 0; loop < token->k5->n_authdata; loop++)
                                toksize += RND(token->k5->authdata[loop].data_len);
                        break;

                default: /* we have a ticket we can't encode */
                        BUG();
                        continue;
                }

                _debug("token[%u]: toksize=%u", ntoks, toksize);
                ASSERTCMP(toksize, <=, AFSTOKEN_LENGTH_MAX);

                toksizes[ntoks++] = toksize;
                size += toksize + 4; /* each token has a length word */
        }

#undef RND

        if (!buffer || buflen < size)
                return size;

        xdr = (__be32 *)buffer;
        zero = 0;
#define ENCODE(x)                               \
        do {                                    \
                *xdr++ = htonl(x);              \
        } while(0)
#define ENCODE_DATA(l, s)                                               \
        do {                                                            \
                u32 _l = (l);                                           \
                ENCODE(l);                                              \
                memcpy(xdr, (s), _l);                                   \
                if (_l & 3)                                             \
                        memcpy((u8 *)xdr + _l, &zero, 4 - (_l & 3));    \
                xdr += (_l + 3) >> 2;                                   \
        } while(0)
#define ENCODE64(x)                                     \
        do {                                            \
                __be64 y = cpu_to_be64(x);              \
                memcpy(xdr, &y, 8);                     \
                xdr += 8 >> 2;                          \
        } while(0)
#define ENCODE_STR(s)                           \
        do {                                    \
                const char *_s = (s);           \
                ENCODE_DATA(strlen(_s), _s);    \
        } while(0)

        ENCODE(0);                                      /* flags */
        ENCODE_DATA(cnlen, key->description + 4);       /* cellname */
        ENCODE(ntoks);

        tok = 0;
        for (token = key->payload.data[0]; token; token = token->next) {
                toksize = toksizes[tok++];
                ENCODE(toksize);
                oldxdr = xdr;
                ENCODE(token->security_index);

                switch (token->security_index) {
                case RXRPC_SECURITY_RXKAD:
                        ENCODE(token->kad->vice_id);
                        ENCODE(token->kad->kvno);
                        ENCODE_DATA(8, token->kad->session_key);
                        ENCODE(token->kad->start);
                        ENCODE(token->kad->expiry);
                        ENCODE(token->kad->primary_flag);
                        ENCODE_DATA(token->kad->ticket_len, token->kad->ticket);
                        break;

                case RXRPC_SECURITY_RXK5:
                        princ = &token->k5->client;
                        ENCODE(princ->n_name_parts);
                        for (loop = 0; loop < princ->n_name_parts; loop++)
                                ENCODE_STR(princ->name_parts[loop]);
                        ENCODE_STR(princ->realm);

                        princ = &token->k5->server;
                        ENCODE(princ->n_name_parts);
                        for (loop = 0; loop < princ->n_name_parts; loop++)
                                ENCODE_STR(princ->name_parts[loop]);
                        ENCODE_STR(princ->realm);

                        ENCODE(token->k5->session.tag);
                        ENCODE_DATA(token->k5->session.data_len,
                                    token->k5->session.data);

                        ENCODE64(token->k5->authtime);
                        ENCODE64(token->k5->starttime);
                        ENCODE64(token->k5->endtime);
                        ENCODE64(token->k5->renew_till);
                        ENCODE(token->k5->is_skey);
                        ENCODE(token->k5->flags);

                        ENCODE(token->k5->n_addresses);
                        for (loop = 0; loop < token->k5->n_addresses; loop++) {
                                ENCODE(token->k5->addresses[loop].tag);
                                ENCODE_DATA(token->k5->addresses[loop].data_len,
                                            token->k5->addresses[loop].data);
                        }

                        ENCODE_DATA(token->k5->ticket_len, token->k5->ticket);
                        ENCODE_DATA(token->k5->ticket2_len, token->k5->ticket2);

                        ENCODE(token->k5->n_authdata);
                        for (loop = 0; loop < token->k5->n_authdata; loop++) {
                                ENCODE(token->k5->authdata[loop].tag);
                                ENCODE_DATA(token->k5->authdata[loop].data_len,
                                            token->k5->authdata[loop].data);
                        }
                        break;

                default:
                        BUG();
                        break;
                }

                ASSERTCMP((unsigned long)xdr - (unsigned long)oldxdr, ==,
                          toksize);
        }

#undef ENCODE_STR
#undef ENCODE_DATA
#undef ENCODE64
#undef ENCODE

        ASSERTCMP(tok, ==, ntoks);
        ASSERTCMP((char __user *) xdr - buffer, ==, size);
        _leave(" = %zu", size);
        return size;
}