gss_krb5_seal.c

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/*
 *  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    <[email protected]>
 *  J. Bruce Fields <[email protected]>
 */

/*
 * 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
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 * USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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 * 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/random.h>
#include <linux/crypto.h>

#ifdef RPC_DEBUG
# define RPCDBG_FACILITY        RPCDBG_AUTH
#endif

DEFINE_SPINLOCK(krb5_seq_lock);

static char *
setup_token(struct krb5_ctx *ctx, struct xdr_netobj *token)
{
    __be16 *ptr, *krb5_hdr;
    int body_size = GSS_KRB5_TOK_HDR_LEN + ctx->gk5e->cksumlength;

    token->len = g_token_size(&ctx->mech_used, body_size);

    ptr = (__be16 *)token->data;
    g_make_token_header(&ctx->mech_used, body_size, (unsigned char **)&ptr);

    /* ptr now at start of header described in rfc 1964, section 1.2.1: */
    krb5_hdr = ptr;
    *ptr++ = KG_TOK_MIC_MSG;
    *ptr++ = cpu_to_le16(ctx->gk5e->signalg);
    *ptr++ = SEAL_ALG_NONE;
    *ptr++ = 0xffff;

    return (char *)krb5_hdr;
}

static void *
setup_token_v2(struct krb5_ctx *ctx, struct xdr_netobj *token)
{
    __be16 *ptr, *krb5_hdr;
    u8 *p, flags = 0x00;

    if ((ctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0)
        flags |= 0x01;
    if (ctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY)
        flags |= 0x04;

    /* Per rfc 4121, sec 4.2.6.1, there is no header,
     * just start the token */
    krb5_hdr = ptr = (__be16 *)token->data;

    *ptr++ = KG2_TOK_MIC;
    p = (u8 *)ptr;
    *p++ = flags;
    *p++ = 0xff;
    ptr = (__be16 *)p;
    *ptr++ = 0xffff;
    *ptr++ = 0xffff;

    token->len = GSS_KRB5_TOK_HDR_LEN + ctx->gk5e->cksumlength;
    return krb5_hdr;
}

static u32
gss_get_mic_v1(struct krb5_ctx *ctx, struct xdr_buf *text,
        struct xdr_netobj *token)
{
    char            cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
    struct xdr_netobj   md5cksum = {.len = sizeof(cksumdata),
                        .data = cksumdata};
    void            *ptr;
    s32         now;
    u32         seq_send;
    u8          *cksumkey;

    dprintk("RPC:       %s\n", __func__);
    BUG_ON(ctx == NULL);

    now = get_seconds();

    ptr = setup_token(ctx, token);

    if (ctx->gk5e->keyed_cksum)
        cksumkey = ctx->cksum;
    else
        cksumkey = NULL;

    if (make_checksum(ctx, ptr, 8, text, 0, cksumkey,
              KG_USAGE_SIGN, &md5cksum))
        return GSS_S_FAILURE;

    memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len);

    spin_lock(&krb5_seq_lock);
    seq_send = ctx->seq_send++;
    spin_unlock(&krb5_seq_lock);

    if (krb5_make_seq_num(ctx, ctx->seq, ctx->initiate ? 0 : 0xff,
                  seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8))
        return GSS_S_FAILURE;

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

static u32
gss_get_mic_v2(struct krb5_ctx *ctx, struct xdr_buf *text,
        struct xdr_netobj *token)
{
    char cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
    struct xdr_netobj cksumobj = { .len = sizeof(cksumdata),
                       .data = cksumdata};
    void *krb5_hdr;
    s32 now;
    u64 seq_send;
    u8 *cksumkey;
    unsigned int cksum_usage;

    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 */
    spin_lock(&krb5_seq_lock);
    seq_send = ctx->seq_send64++;
    spin_unlock(&krb5_seq_lock);
    *((u64 *)(krb5_hdr + 8)) = cpu_to_be64(seq_send);

    if (ctx->initiate) {
        cksumkey = ctx->initiator_sign;
        cksum_usage = KG_USAGE_INITIATOR_SIGN;
    } else {
        cksumkey = ctx->acceptor_sign;
        cksum_usage = KG_USAGE_ACCEPTOR_SIGN;
    }

    if (make_checksum_v2(ctx, krb5_hdr, GSS_KRB5_TOK_HDR_LEN,
                 text, 0, cksumkey, cksum_usage, &cksumobj))
        return GSS_S_FAILURE;

    memcpy(krb5_hdr + GSS_KRB5_TOK_HDR_LEN, cksumobj.data, cksumobj.len);

    now = get_seconds();

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

u32
gss_get_mic_kerberos(struct gss_ctx *gss_ctx, struct xdr_buf *text,
             struct xdr_netobj *token)
{
    struct krb5_ctx     *ctx = gss_ctx->internal_ctx_id;

    switch (ctx->enctype) {
    default:
        BUG();
    case ENCTYPE_DES_CBC_RAW:
    case ENCTYPE_DES3_CBC_RAW:
    case ENCTYPE_ARCFOUR_HMAC:
        return gss_get_mic_v1(ctx, text, token);
    case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
    case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
        return gss_get_mic_v2(ctx, text, token);
    }
}