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 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/slab.h> 62 #include <linux/jiffies.h> 63 #include <linux/sunrpc/gss_krb5.h> 64 #include <linux/crypto.h> 65 66 #ifdef RPC_DEBUG 67 # define RPCDBG_FACILITY RPCDBG_AUTH 68 #endif 69 70 71 /* read_token is a mic token, and message_buffer is the data that the mic was 72 * supposedly taken over. */ 73 74 u32 75 gss_verify_mic_kerberos(struct gss_ctx *gss_ctx, 76 struct xdr_buf *message_buffer, struct xdr_netobj *read_token) 77 { 78 struct krb5_ctx *ctx = gss_ctx->internal_ctx_id; 79 int signalg; 80 int sealalg; 81 s32 checksum_type; 82 char cksumdata[16]; 83 struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata}; 84 s32 now; 85 int direction; 86 s32 seqnum; 87 unsigned char *ptr = (unsigned char *)read_token->data; 88 int bodysize; 89 u32 ret = GSS_S_DEFECTIVE_TOKEN; 90 91 dprintk("RPC: krb5_read_token\n"); 92 93 if (g_verify_token_header(&ctx->mech_used, &bodysize, &ptr, 94 read_token->len)) 95 goto out; 96 97 if ((*ptr++ != ((KG_TOK_MIC_MSG>>8)&0xff)) || 98 (*ptr++ != ( KG_TOK_MIC_MSG &0xff)) ) 99 goto out; 100 101 /* XXX sanity-check bodysize?? */ 102 103 /* get the sign and seal algorithms */ 104 105 signalg = ptr[0] + (ptr[1] << 8); 106 sealalg = ptr[2] + (ptr[3] << 8); 107 108 /* Sanity checks */ 109 110 if ((ptr[4] != 0xff) || (ptr[5] != 0xff)) 111 goto out; 112 113 if (sealalg != 0xffff) 114 goto out; 115 116 /* there are several mappings of seal algorithms to sign algorithms, 117 but few enough that we can try them all. */ 118 119 if ((ctx->sealalg == SEAL_ALG_NONE && signalg > 1) || 120 (ctx->sealalg == SEAL_ALG_1 && signalg != SGN_ALG_3) || 121 (ctx->sealalg == SEAL_ALG_DES3KD && 122 signalg != SGN_ALG_HMAC_SHA1_DES3_KD)) 123 goto out; 124 125 /* compute the checksum of the message */ 126 127 /* initialize the the cksum */ 128 switch (signalg) { 129 case SGN_ALG_DES_MAC_MD5: 130 checksum_type = CKSUMTYPE_RSA_MD5; 131 break; 132 default: 133 ret = GSS_S_DEFECTIVE_TOKEN; 134 goto out; 135 } 136 137 switch (signalg) { 138 case SGN_ALG_DES_MAC_MD5: 139 ret = make_checksum(checksum_type, ptr - 2, 8, 140 message_buffer, 0, &md5cksum); 141 if (ret) 142 goto out; 143 144 ret = krb5_encrypt(ctx->seq, NULL, md5cksum.data, 145 md5cksum.data, 16); 146 if (ret) 147 goto out; 148 149 if (memcmp(md5cksum.data + 8, ptr + 14, 8)) { 150 ret = GSS_S_BAD_SIG; 151 goto out; 152 } 153 break; 154 default: 155 ret = GSS_S_DEFECTIVE_TOKEN; 156 goto out; 157 } 158 159 /* it got through unscathed. Make sure the context is unexpired */ 160 161 now = get_seconds(); 162 163 ret = GSS_S_CONTEXT_EXPIRED; 164 if (now > ctx->endtime) 165 goto out; 166 167 /* do sequencing checks */ 168 169 ret = GSS_S_BAD_SIG; 170 if ((ret = krb5_get_seq_num(ctx->seq, ptr + 14, ptr + 6, &direction, 171 &seqnum))) 172 goto out; 173 174 if ((ctx->initiate && direction != 0xff) || 175 (!ctx->initiate && direction != 0)) 176 goto out; 177 178 ret = GSS_S_COMPLETE; 179 out: 180 return ret; 181 } 182