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 /* message_buffer is an input if toktype is MIC and an output if it is WRAP: 72 * If toktype is MIC: read_token is a mic token, and message_buffer is the 73 * data that the mic was supposedly taken over. 74 * If toktype is WRAP: read_token is a wrap token, and message_buffer is used 75 * to return the decrypted data. 76 */ 77 78 /* XXX will need to change prototype and/or just split into a separate function 79 * when we add privacy (because read_token will be in pages too). */ 80 u32 81 krb5_read_token(struct krb5_ctx *ctx, 82 struct xdr_netobj *read_token, 83 struct xdr_buf *message_buffer, 84 int *qop_state, int toktype) 85 { 86 int signalg; 87 int sealalg; 88 s32 checksum_type; 89 struct xdr_netobj md5cksum = {.len = 0, .data = NULL}; 90 s32 now; 91 int direction; 92 s32 seqnum; 93 unsigned char *ptr = (unsigned char *)read_token->data; 94 int bodysize; 95 u32 ret = GSS_S_DEFECTIVE_TOKEN; 96 97 dprintk("RPC: krb5_read_token\n"); 98 99 if (g_verify_token_header(&ctx->mech_used, &bodysize, &ptr, 100 read_token->len)) 101 goto out; 102 103 if ((*ptr++ != ((toktype>>8)&0xff)) || (*ptr++ != (toktype&0xff))) 104 goto out; 105 106 /* XXX sanity-check bodysize?? */ 107 108 if (toktype == KG_TOK_WRAP_MSG) { 109 /* XXX gone */ 110 goto out; 111 } 112 113 /* get the sign and seal algorithms */ 114 115 signalg = ptr[0] + (ptr[1] << 8); 116 sealalg = ptr[2] + (ptr[3] << 8); 117 118 /* Sanity checks */ 119 120 if ((ptr[4] != 0xff) || (ptr[5] != 0xff)) 121 goto out; 122 123 if (((toktype != KG_TOK_WRAP_MSG) && (sealalg != 0xffff)) || 124 ((toktype == KG_TOK_WRAP_MSG) && (sealalg == 0xffff))) 125 goto out; 126 127 /* in the current spec, there is only one valid seal algorithm per 128 key type, so a simple comparison is ok */ 129 130 if ((toktype == KG_TOK_WRAP_MSG) && !(sealalg == ctx->sealalg)) 131 goto out; 132 133 /* there are several mappings of seal algorithms to sign algorithms, 134 but few enough that we can try them all. */ 135 136 if ((ctx->sealalg == SEAL_ALG_NONE && signalg > 1) || 137 (ctx->sealalg == SEAL_ALG_1 && signalg != SGN_ALG_3) || 138 (ctx->sealalg == SEAL_ALG_DES3KD && 139 signalg != SGN_ALG_HMAC_SHA1_DES3_KD)) 140 goto out; 141 142 /* compute the checksum of the message */ 143 144 /* initialize the the cksum */ 145 switch (signalg) { 146 case SGN_ALG_DES_MAC_MD5: 147 checksum_type = CKSUMTYPE_RSA_MD5; 148 break; 149 default: 150 ret = GSS_S_DEFECTIVE_TOKEN; 151 goto out; 152 } 153 154 switch (signalg) { 155 case SGN_ALG_DES_MAC_MD5: 156 ret = make_checksum(checksum_type, ptr - 2, 8, 157 message_buffer, &md5cksum); 158 if (ret) 159 goto out; 160 161 ret = krb5_encrypt(ctx->seq, NULL, md5cksum.data, 162 md5cksum.data, 16); 163 if (ret) 164 goto out; 165 166 if (memcmp(md5cksum.data + 8, ptr + 14, 8)) { 167 ret = GSS_S_BAD_SIG; 168 goto out; 169 } 170 break; 171 default: 172 ret = GSS_S_DEFECTIVE_TOKEN; 173 goto out; 174 } 175 176 /* it got through unscathed. Make sure the context is unexpired */ 177 178 if (qop_state) 179 *qop_state = GSS_C_QOP_DEFAULT; 180 181 now = get_seconds(); 182 183 ret = GSS_S_CONTEXT_EXPIRED; 184 if (now > ctx->endtime) 185 goto out; 186 187 /* do sequencing checks */ 188 189 ret = GSS_S_BAD_SIG; 190 if ((ret = krb5_get_seq_num(ctx->seq, ptr + 14, ptr + 6, &direction, 191 &seqnum))) 192 goto out; 193 194 if ((ctx->initiate && direction != 0xff) || 195 (!ctx->initiate && direction != 0)) 196 goto out; 197 198 ret = GSS_S_COMPLETE; 199 out: 200 if (md5cksum.data) kfree(md5cksum.data); 201 return ret; 202 } 203