LXR linux/net/sunrpc/auth_gss/gss_krb5

   1/*
   2 *  linux/net/sunrpc/gss_krb5_unseal.c
   3 *
   4 *  Adapted from MIT Kerberos 5-1.2.1 lib/gssapi/krb5/k5unseal.c
   5 *
   6 *  Copyright (c) 2000-2008 The Regents of the University of Michigan.
   7 *  All rights reserved.
   8 *
   9 *  Andy Adamson   <andros@umich.edu>
  10 */
  11
  12/*
  13 * Copyright 1993 by OpenVision Technologies, Inc.
  14 *
  15 * Permission to use, copy, modify, distribute, and sell this software
  16 * and its documentation for any purpose is hereby granted without fee,
  17 * provided that the above copyright notice appears in all copies and
  18 * that both that copyright notice and this permission notice appear in
  19 * supporting documentation, and that the name of OpenVision not be used
  20 * in advertising or publicity pertaining to distribution of the software
  21 * without specific, written prior permission. OpenVision makes no
  22 * representations about the suitability of this software for any
  23 * purpose.  It is provided "as is" without express or implied warranty.
  24 *
  25 * OPENVISION DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  26 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  27 * EVENT SHALL OPENVISION BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  28 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
  29 * USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
  30 * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  31 * PERFORMANCE OF THIS SOFTWARE.
  32 */
  33
  34/*
  35 * Copyright (C) 1998 by the FundsXpress, INC.
  36 *
  37 * All rights reserved.
  38 *
  39 * Export of this software from the United States of America may require
  40 * a specific license from the United States Government.  It is the
  41 * responsibility of any person or organization contemplating export to
  42 * obtain such a license before exporting.
  43 *
  44 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
  45 * distribute this software and its documentation for any purpose and
  46 * without fee is hereby granted, provided that the above copyright
  47 * notice appear in all copies and that both that copyright notice and
  48 * this permission notice appear in supporting documentation, and that
  49 * the name of FundsXpress. not be used in advertising or publicity pertaining
  50 * to distribution of the software without specific, written prior
  51 * permission.  FundsXpress makes no representations about the suitability of
  52 * this software for any purpose.  It is provided "as is" without express
  53 * or implied warranty.
  54 *
  55 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  56 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  57 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  58 */
  59
  60#include <linux/types.h>
  61#include <linux/jiffies.h>
  62#include <linux/sunrpc/gss_krb5.h>
  63#include <linux/crypto.h>
  64
  65#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
  66# define RPCDBG_FACILITY        RPCDBG_AUTH
  67#endif
  68
  69
  70/* read_token is a mic token, and message_buffer is the data that the mic was
  71 * supposedly taken over. */
  72
  73static u32
  74gss_verify_mic_v1(struct krb5_ctx *ctx,
  75                struct xdr_buf *message_buffer, struct xdr_netobj *read_token)
  76{
  77        int                     signalg;
  78        int                     sealalg;
  79        char                    cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
  80        struct xdr_netobj       md5cksum = {.len = sizeof(cksumdata),
  81                                            .data = cksumdata};
  82        s32                     now;
  83        int                     direction;
  84        u32                     seqnum;
  85        unsigned char           *ptr = (unsigned char *)read_token->data;
  86        int                     bodysize;
  87        u8                      *cksumkey;
  88
  89        dprintk("RPC:       krb5_read_token\n");
  90
  91        if (g_verify_token_header(&ctx->mech_used, &bodysize, &ptr,
  92                                        read_token->len))
  93                return GSS_S_DEFECTIVE_TOKEN;
  94
  95        if ((ptr[0] != ((KG_TOK_MIC_MSG >> 8) & 0xff)) ||
  96            (ptr[1] !=  (KG_TOK_MIC_MSG & 0xff)))
  97                return GSS_S_DEFECTIVE_TOKEN;
  98
  99        /* XXX sanity-check bodysize?? */
 100
 101        signalg = ptr[2] + (ptr[3] << 8);
 102        if (signalg != ctx->gk5e->signalg)
 103                return GSS_S_DEFECTIVE_TOKEN;
 104
 105        sealalg = ptr[4] + (ptr[5] << 8);
 106        if (sealalg != SEAL_ALG_NONE)
 107                return GSS_S_DEFECTIVE_TOKEN;
 108
 109        if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
 110                return GSS_S_DEFECTIVE_TOKEN;
 111
 112        if (ctx->gk5e->keyed_cksum)
 113                cksumkey = ctx->cksum;
 114        else
 115                cksumkey = NULL;
 116
 117        if (make_checksum(ctx, ptr, 8, message_buffer, 0,
 118                          cksumkey, KG_USAGE_SIGN, &md5cksum))
 119                return GSS_S_FAILURE;
 120
 121        if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN,
 122                                        ctx->gk5e->cksumlength))
 123                return GSS_S_BAD_SIG;
 124
 125        /* it got through unscathed.  Make sure the context is unexpired */
 126
 127        now = get_seconds();
 128
 129        if (now > ctx->endtime)
 130                return GSS_S_CONTEXT_EXPIRED;
 131
 132        /* do sequencing checks */
 133
 134        if (krb5_get_seq_num(ctx, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8,
 135                             &direction, &seqnum))
 136                return GSS_S_FAILURE;
 137
 138        if ((ctx->initiate && direction != 0xff) ||
 139            (!ctx->initiate && direction != 0))
 140                return GSS_S_BAD_SIG;
 141
 142        return GSS_S_COMPLETE;
 143}
 144
 145static u32
 146gss_verify_mic_v2(struct krb5_ctx *ctx,
 147                struct xdr_buf *message_buffer, struct xdr_netobj *read_token)
 148{
 149        char cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
 150        struct xdr_netobj cksumobj = {.len = sizeof(cksumdata),
 151                                      .data = cksumdata};
 152        s32 now;
 153        u8 *ptr = read_token->data;
 154        u8 *cksumkey;
 155        u8 flags;
 156        int i;
 157        unsigned int cksum_usage;
 158
 159        dprintk("RPC:       %s\n", __func__);
 160
 161        if (be16_to_cpu(*((__be16 *)ptr)) != KG2_TOK_MIC)
 162                return GSS_S_DEFECTIVE_TOKEN;
 163
 164        flags = ptr[2];
 165        if ((!ctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) ||
 166            (ctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)))
 167                return GSS_S_BAD_SIG;
 168
 169        if (flags & KG2_TOKEN_FLAG_SEALED) {
 170                dprintk("%s: token has unexpected sealed flag\n", __func__);
 171                return GSS_S_FAILURE;
 172        }
 173
 174        for (i = 3; i < 8; i++)
 175                if (ptr[i] != 0xff)
 176                        return GSS_S_DEFECTIVE_TOKEN;
 177
 178        if (ctx->initiate) {
 179                cksumkey = ctx->acceptor_sign;
 180                cksum_usage = KG_USAGE_ACCEPTOR_SIGN;
 181        } else {
 182                cksumkey = ctx->initiator_sign;
 183                cksum_usage = KG_USAGE_INITIATOR_SIGN;
 184        }
 185
 186        if (make_checksum_v2(ctx, ptr, GSS_KRB5_TOK_HDR_LEN, message_buffer, 0,
 187                             cksumkey, cksum_usage, &cksumobj))
 188                return GSS_S_FAILURE;
 189
 190        if (memcmp(cksumobj.data, ptr + GSS_KRB5_TOK_HDR_LEN,
 191                                ctx->gk5e->cksumlength))
 192                return GSS_S_BAD_SIG;
 193
 194        /* it got through unscathed.  Make sure the context is unexpired */
 195        now = get_seconds();
 196        if (now > ctx->endtime)
 197                return GSS_S_CONTEXT_EXPIRED;
 198
 199        /*
 200         * NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss
 201         * doesn't want it checked; see page 6 of rfc 2203.
 202         */
 203
 204        return GSS_S_COMPLETE;
 205}
 206
 207u32
 208gss_verify_mic_kerberos(struct gss_ctx *gss_ctx,
 209                        struct xdr_buf *message_buffer,
 210                        struct xdr_netobj *read_token)
 211{
 212        struct krb5_ctx *ctx = gss_ctx->internal_ctx_id;
 213
 214        switch (ctx->enctype) {
 215        default:
 216                BUG();
 217        case ENCTYPE_DES_CBC_RAW:
 218        case ENCTYPE_DES3_CBC_RAW:
 219        case ENCTYPE_ARCFOUR_HMAC:
 220                return gss_verify_mic_v1(ctx, message_buffer, read_token);
 221        case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
 222        case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
 223                return gss_verify_mic_v2(ctx, message_buffer, read_token);
 224        }
 225}
 226
 227