// SPDX-License-Identifier: GPL-2.0-or-later
/* RxRPC key management
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * RxRPC keys should have a description of describing their purpose:
 *      "afs@example.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_preparse(struct key_preparsed_payload *);
static void rxrpc_free_preparse(struct key_preparsed_payload *);
static void rxrpc_destroy(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",
        .flags          = KEY_TYPE_NET_DOMAIN,
        .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);

/*
 * 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;
}

/*
 * 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, *p;
        const char *cp;
        unsigned int len, paddedlen, loop, ntoken, toklen, sec_ix;
        size_t datalen = prep->datalen;
        int ret, ret2;

        _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 */
        p = xdr;
        loop = ntoken;
        do {
                if (datalen < 8)
                        goto not_xdr;
                toklen = ntohl(*p++);
                sec_ix = ntohl(*p);
                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;
                p += 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
         */
        ret = -EPROTONOSUPPORT;
        do {
                toklen = ntohl(*xdr++);
                token = xdr;
                xdr += (toklen + 3) / 4;

                sec_ix = ntohl(*token++);
                toklen -= 4;

                _debug("TOKEN type=%x len=%x", sec_ix, toklen);

                switch (sec_ix) {
                case RXRPC_SECURITY_RXKAD:
                        ret2 = rxrpc_preparse_xdr_rxkad(prep, datalen, token, toklen);
                        break;
                default:
                        ret2 = -EPROTONOSUPPORT;
                        break;
                }

                switch (ret2) {
                case 0:
                        ret = 0;
                        break;
                case -EPROTONOSUPPORT:
                        break;
                case -ENOPKG:
                        if (ret != 0)
                                ret = -ENOPKG;
                        break;
                default:
                        ret = ret2;
                        goto error;
                }

        } while (--ntoken > 0);

error:
        _leave(" = %d", ret);
        return ret;

not_xdr:
        _leave(" = -EPROTO");
        return -EPROTO;
}

/*
 * 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;
                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]);
}

/*
 * 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]);
}

/*
 * describe the rxrpc key
 */
static void rxrpc_describe(const struct key *key, struct seq_file *m)
{
        const struct rxrpc_key_token *token;
        const char *sep = ": ";

        seq_puts(m, key->description);

        for (token = key->payload.data[0]; token; token = token->next) {
                seq_puts(m, sep);

                switch (token->security_index) {
                case RXRPC_SECURITY_RXKAD:
                        seq_puts(m, "ka");
                        break;
                default: /* we have a ticket we can't encode */
                        seq_printf(m, "%u", token->security_index);
                        break;
                }

                sep = " ";
        }
}

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

        _enter("");

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

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

        key = request_key_net(&key_type_rxrpc, description, sock_net(&rx->sk), 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;
}

/*
 * 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;
        size_t size;
        __be32 *xdr, *oldxdr;
        u32 cnlen, toksize, ntoks, tok, zero;
        u16 toksizes[AFSTOKEN_MAX];

        _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 += 8 * 4;       /* viceid, kvno, key*2, begin,
                                                 * end, primary, tktlen */
                        if (!token->no_leak_key)
                                toksize += RND(token->kad->ticket_len);
                        break;

                default: /* we have a ticket we can't encode */
                        pr_err("Unsupported key token type (%u)\n",
                               token->security_index);
                        return -ENOPKG;
                }

                _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 ENCODE_BYTES(l, s)                                              \
        do {                                                            \
                u32 _l = (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_BYTES(8, token->kad->session_key);
                        ENCODE(token->kad->start);
                        ENCODE(token->kad->expiry);
                        ENCODE(token->kad->primary_flag);
                        if (token->no_leak_key)
                                ENCODE(0);
                        else
                                ENCODE_DATA(token->kad->ticket_len, token->kad->ticket);
                        break;

                default:
                        pr_err("Unsupported key token type (%u)\n",
                               token->security_index);
                        return -ENOPKG;
                }

                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;
}