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 <crypto/algapi.h> 61 #include <linux/types.h> 62 #include <linux/jiffies.h> 63 #include <linux/sunrpc/gss_krb5.h> 64 #include <linux/crypto.h> 65 66 #include "gss_krb5_internal.h" 67 68 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) 69 # define RPCDBG_FACILITY RPCDBG_AUTH 70 #endif 71 72 73 #if defined(CONFIG_RPCSEC_GSS_KRB5_SIMPLIFIED) 74 /* read_token is a mic token, and message_buffer is the data that the mic was 75 * supposedly taken over. */ 76 u32 77 gss_krb5_verify_mic_v1(struct krb5_ctx *ctx, struct xdr_buf *message_buffer, 78 struct xdr_netobj *read_token) 79 { 80 int signalg; 81 int sealalg; 82 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN]; 83 struct xdr_netobj md5cksum = {.len = sizeof(cksumdata), 84 .data = cksumdata}; 85 s32 now; 86 int direction; 87 u32 seqnum; 88 unsigned char *ptr = (unsigned char *)read_token->data; 89 int bodysize; 90 u8 *cksumkey; 91 92 dprintk("RPC: krb5_read_token\n"); 93 94 if (g_verify_token_header(&ctx->mech_used, &bodysize, &ptr, 95 read_token->len)) 96 return GSS_S_DEFECTIVE_TOKEN; 97 98 if ((ptr[0] != ((KG_TOK_MIC_MSG >> 8) & 0xff)) || 99 (ptr[1] != (KG_TOK_MIC_MSG & 0xff))) 100 return GSS_S_DEFECTIVE_TOKEN; 101 102 /* XXX sanity-check bodysize?? */ 103 104 signalg = ptr[2] + (ptr[3] << 8); 105 if (signalg != ctx->gk5e->signalg) 106 return GSS_S_DEFECTIVE_TOKEN; 107 108 sealalg = ptr[4] + (ptr[5] << 8); 109 if (sealalg != SEAL_ALG_NONE) 110 return GSS_S_DEFECTIVE_TOKEN; 111 112 if ((ptr[6] != 0xff) || (ptr[7] != 0xff)) 113 return GSS_S_DEFECTIVE_TOKEN; 114 115 if (ctx->gk5e->keyed_cksum) 116 cksumkey = ctx->cksum; 117 else 118 cksumkey = NULL; 119 120 if (make_checksum(ctx, ptr, 8, message_buffer, 0, 121 cksumkey, KG_USAGE_SIGN, &md5cksum)) 122 return GSS_S_FAILURE; 123 124 if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN, 125 ctx->gk5e->cksumlength)) 126 return GSS_S_BAD_SIG; 127 128 /* it got through unscathed. Make sure the context is unexpired */ 129 130 now = ktime_get_real_seconds(); 131 132 if (now > ctx->endtime) 133 return GSS_S_CONTEXT_EXPIRED; 134 135 /* do sequencing checks */ 136 137 if (krb5_get_seq_num(ctx, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8, 138 &direction, &seqnum)) 139 return GSS_S_FAILURE; 140 141 if ((ctx->initiate && direction != 0xff) || 142 (!ctx->initiate && direction != 0)) 143 return GSS_S_BAD_SIG; 144 145 return GSS_S_COMPLETE; 146 } 147 #endif 148 149 u32 150 gss_krb5_verify_mic_v2(struct krb5_ctx *ctx, struct xdr_buf *message_buffer, 151 struct xdr_netobj *read_token) 152 { 153 struct crypto_ahash *tfm = ctx->initiate ? 154 ctx->acceptor_sign : ctx->initiator_sign; 155 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN]; 156 struct xdr_netobj cksumobj = { 157 .len = ctx->gk5e->cksumlength, 158 .data = cksumdata, 159 }; 160 u8 *ptr = read_token->data; 161 __be16 be16_ptr; 162 time64_t now; 163 u8 flags; 164 int i; 165 166 dprintk("RPC: %s\n", __func__); 167 168 memcpy(&be16_ptr, (char *) ptr, 2); 169 if (be16_to_cpu(be16_ptr) != KG2_TOK_MIC) 170 return GSS_S_DEFECTIVE_TOKEN; 171 172 flags = ptr[2]; 173 if ((!ctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) || 174 (ctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR))) 175 return GSS_S_BAD_SIG; 176 177 if (flags & KG2_TOKEN_FLAG_SEALED) { 178 dprintk("%s: token has unexpected sealed flag\n", __func__); 179 return GSS_S_FAILURE; 180 } 181 182 for (i = 3; i < 8; i++) 183 if (ptr[i] != 0xff) 184 return GSS_S_DEFECTIVE_TOKEN; 185 186 if (gss_krb5_checksum(tfm, ptr, GSS_KRB5_TOK_HDR_LEN, 187 message_buffer, 0, &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 = ktime_get_real_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