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
  64 #include "gss_krb5_internal.h"
  65
  66 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
  67 # define RPCDBG_FACILITY        RPCDBG_AUTH
  68 #endif
  69
  70 u32
  71 gss_krb5_verify_mic_v2(struct krb5_ctx *ctx, struct xdr_buf *message_buffer,
  72                        struct xdr_netobj *read_token)
  73 {
  74         struct crypto_ahash *tfm = ctx->initiate ?
  75                                    ctx->acceptor_sign : ctx->initiator_sign;
  76         char cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
  77         struct xdr_netobj cksumobj = {
  78                 .len    = ctx->gk5e->cksumlength,
  79                 .data   = cksumdata,
  80         };
  81         u8 *ptr = read_token->data;
  82         __be16 be16_ptr;
  83         time64_t now;
  84         u8 flags;
  85         int i;
  86
  87         dprintk("RPC:       %s\n", __func__);
  88
  89         memcpy(&be16_ptr, (char *) ptr, 2);
  90         if (be16_to_cpu(be16_ptr) != KG2_TOK_MIC)
  91                 return GSS_S_DEFECTIVE_TOKEN;
  92
  93         flags = ptr[2];
  94         if ((!ctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) ||
  95             (ctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)))
  96                 return GSS_S_BAD_SIG;
  97
  98         if (flags & KG2_TOKEN_FLAG_SEALED) {
  99                 dprintk("%s: token has unexpected sealed flag\n", __func__);
 100                 return GSS_S_FAILURE;
 101         }
 102
 103         for (i = 3; i < 8; i++)
 104                 if (ptr[i] != 0xff)
 105                         return GSS_S_DEFECTIVE_TOKEN;
 106
 107         if (gss_krb5_checksum(tfm, ptr, GSS_KRB5_TOK_HDR_LEN,
 108                               message_buffer, 0, &cksumobj))
 109                 return GSS_S_FAILURE;
 110
 111         if (memcmp(cksumobj.data, ptr + GSS_KRB5_TOK_HDR_LEN,
 112                                 ctx->gk5e->cksumlength))
 113                 return GSS_S_BAD_SIG;
 114
 115         /* it got through unscathed.  Make sure the context is unexpired */
 116         now = ktime_get_real_seconds();
 117         if (now > ctx->endtime)
 118                 return GSS_S_CONTEXT_EXPIRED;
 119
 120         /*
 121          * NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss
 122          * doesn't want it checked; see page 6 of rfc 2203.
 123          */
 124
 125         return GSS_S_COMPLETE;
 126 }