net/sunrpc/auth_gss/gss_krb5_unseal.c

   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
  73 static u32
  74 gss_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
 145 static u32
 146 gss_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         __be16 be16_ptr;
 159
 160         dprintk("RPC:       %s\n", __func__);
 161
 162         memcpy(&be16_ptr, (char *) ptr, 2);
 163         if (be16_to_cpu(be16_ptr) != KG2_TOK_MIC)
 164                 return GSS_S_DEFECTIVE_TOKEN;
 165
 166         flags = ptr[2];
 167         if ((!ctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) ||
 168             (ctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)))
 169                 return GSS_S_BAD_SIG;
 170
 171         if (flags & KG2_TOKEN_FLAG_SEALED) {
 172                 dprintk("%s: token has unexpected sealed flag\n", __func__);
 173                 return GSS_S_FAILURE;
 174         }
 175
 176         for (i = 3; i < 8; i++)
 177                 if (ptr[i] != 0xff)
 178                         return GSS_S_DEFECTIVE_TOKEN;
 179
 180         if (ctx->initiate) {
 181                 cksumkey = ctx->acceptor_sign;
 182                 cksum_usage = KG_USAGE_ACCEPTOR_SIGN;
 183         } else {
 184                 cksumkey = ctx->initiator_sign;
 185                 cksum_usage = KG_USAGE_INITIATOR_SIGN;
 186         }
 187
 188         if (make_checksum_v2(ctx, ptr, GSS_KRB5_TOK_HDR_LEN, message_buffer, 0,
 189                              cksumkey, cksum_usage, &cksumobj))
 190                 return GSS_S_FAILURE;
 191
 192         if (memcmp(cksumobj.data, ptr + GSS_KRB5_TOK_HDR_LEN,
 193                                 ctx->gk5e->cksumlength))
 194                 return GSS_S_BAD_SIG;
 195
 196         /* it got through unscathed.  Make sure the context is unexpired */
 197         now = get_seconds();
 198         if (now > ctx->endtime)
 199                 return GSS_S_CONTEXT_EXPIRED;
 200
 201         /*
 202          * NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss
 203          * doesn't want it checked; see page 6 of rfc 2203.
 204          */
 205
 206         return GSS_S_COMPLETE;
 207 }
 208
 209 u32
 210 gss_verify_mic_kerberos(struct gss_ctx *gss_ctx,
 211                         struct xdr_buf *message_buffer,
 212                         struct xdr_netobj *read_token)
 213 {
 214         struct krb5_ctx *ctx = gss_ctx->internal_ctx_id;
 215
 216         switch (ctx->enctype) {
 217         default:
 218                 BUG();
 219         case ENCTYPE_DES_CBC_RAW:
 220         case ENCTYPE_DES3_CBC_RAW:
 221         case ENCTYPE_ARCFOUR_HMAC:
 222                 return gss_verify_mic_v1(ctx, message_buffer, read_token);
 223         case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
 224         case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
 225                 return gss_verify_mic_v2(ctx, message_buffer, read_token);
 226         }
 227 }