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; 158 159 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 } 206 207 u32 208 gss_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