/*
 *  linux/net/sunrpc/gss_krb5_seal.c
 *
 *  Adapted from MIT Kerberos 5-1.2.1 lib/gssapi/krb5/k5seal.c
 *
 *  Copyright (c) 2000-2008 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Andy Adamson        <andros@umich.edu>
 *  J. Bruce Fields     <bfields@umich.edu>
 */

/*
 * Copyright 1993 by OpenVision Technologies, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appears in all copies and
 * that both that copyright notice and this permission notice appear in
 * supporting documentation, and that the name of OpenVision not be used
 * in advertising or publicity pertaining to distribution of the software
 * without specific, written prior permission. OpenVision makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 *
 * OPENVISION DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL OPENVISION BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
 * USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
 * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * Copyright (C) 1998 by the FundsXpress, INC.
 *
 * All rights reserved.
 *
 * Export of this software from the United States of America may require
 * a specific license from the United States Government.  It is the
 * responsibility of any person or organization contemplating export to
 * obtain such a license before exporting.
 *
 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
 * distribute this software and its documentation for any purpose and
 * without fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright notice and
 * this permission notice appear in supporting documentation, and that
 * the name of FundsXpress. not be used in advertising or publicity pertaining
 * to distribution of the software without specific, written prior
 * permission.  FundsXpress makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is" without express
 * or implied warranty.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include <linux/types.h>
#include <linux/jiffies.h>
#include <linux/sunrpc/gss_krb5.h>
#include <linux/atomic.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>

#include "gss_krb5_internal.h"

#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
# define RPCDBG_FACILITY        RPCDBG_AUTH
#endif

static void *
setup_token_v2(struct krb5_ctx *ctx, struct xdr_netobj *token)
{
        u16 *ptr;
        void *krb5_hdr;
        u8 *p, flags = 0x00;

        if (!ctx->initiate)
                flags |= KG2_TOKEN_FLAG_SENTBYACCEPTOR;
        if (ctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY)
                flags |= KG2_TOKEN_FLAG_ACCEPTORSUBKEY;

        /* Per rfc 4121, sec 4.2.6.1, there is no header,
         * just start the token.
         */
        krb5_hdr = (u16 *)token->data;
        ptr = krb5_hdr;

        *ptr++ = KG2_TOK_MIC;
        p = (u8 *)ptr;
        *p++ = flags;
        *p++ = 0xff;
        ptr = (u16 *)p;
        *ptr++ = 0xffff;
        *ptr = 0xffff;

        token->len = GSS_KRB5_TOK_HDR_LEN + ctx->krb5e->cksum_len;
        return krb5_hdr;
}

u32
gss_krb5_get_mic_v2(struct krb5_ctx *ctx, struct xdr_buf *text,
                    struct xdr_netobj *token)
{
        const struct krb5_enctype *krb5 = ctx->krb5e;
        struct crypto_shash *shash = ctx->initiate ?
                ctx->initiator_sign_shash : ctx->acceptor_sign_shash;
        unsigned int cksum_len = krb5->cksum_len;
        struct scatterlist sg_head[XDR_BUF_TO_SG_NENTS];
        struct scatterlist *sg_overflow;
        __be64 seq_send_be64;
        void *krb5_hdr;
        time64_t now;
        ssize_t ret;
        int nsg;

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

        krb5_hdr = setup_token_v2(ctx, token);

        /* Set up the sequence number. Now 64-bits in clear
         * text and w/o direction indicator */
        seq_send_be64 = cpu_to_be64(atomic64_fetch_inc(&ctx->seq_send64));
        memcpy(krb5_hdr + 8, (char *) &seq_send_be64, 8);

        /*
         * The checksum is written directly into the token buffer.
         * This is safe: crypto_krb5_get_mic uses shash (software
         * hash), so the scatterlist is never DMA-mapped.
         */
        nsg = gss_krb5_mic_build_sg(text,
                                    krb5_hdr + GSS_KRB5_TOK_HDR_LEN,
                                    cksum_len, krb5_hdr,
                                    sg_head, &sg_overflow);
        if (nsg < 0)
                return GSS_S_FAILURE;

        ret = crypto_krb5_get_mic(krb5, shash, NULL, sg_head, nsg,
                                  cksum_len + text->len +
                                        GSS_KRB5_TOK_HDR_LEN,
                                  cksum_len,
                                  text->len + GSS_KRB5_TOK_HDR_LEN);
        kfree(sg_overflow);
        if (ret < 0)
                return GSS_S_FAILURE;

        now = ktime_get_real_seconds();
        return (ctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
}