1 /*
2  *  linux/net/sunrpc/gss_krb5_seal.c
3  *
4  *  Adapted from MIT Kerberos 5-1.2.1 lib/gssapi/krb5/k5seal.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  *  J. Bruce Fields	<bfields@umich.edu>
11  */
12 
13 /*
14  * Copyright 1993 by OpenVision Technologies, Inc.
15  *
16  * Permission to use, copy, modify, distribute, and sell this software
17  * and its documentation for any purpose is hereby granted without fee,
18  * provided that the above copyright notice appears in all copies and
19  * that both that copyright notice and this permission notice appear in
20  * supporting documentation, and that the name of OpenVision not be used
21  * in advertising or publicity pertaining to distribution of the software
22  * without specific, written prior permission. OpenVision makes no
23  * representations about the suitability of this software for any
24  * purpose.  It is provided "as is" without express or implied warranty.
25  *
26  * OPENVISION DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
27  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
28  * EVENT SHALL OPENVISION BE LIABLE FOR ANY SPECIAL, INDIRECT OR
29  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
30  * USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
31  * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
32  * PERFORMANCE OF THIS SOFTWARE.
33  */
34 
35 /*
36  * Copyright (C) 1998 by the FundsXpress, INC.
37  *
38  * All rights reserved.
39  *
40  * Export of this software from the United States of America may require
41  * a specific license from the United States Government.  It is the
42  * responsibility of any person or organization contemplating export to
43  * obtain such a license before exporting.
44  *
45  * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
46  * distribute this software and its documentation for any purpose and
47  * without fee is hereby granted, provided that the above copyright
48  * notice appear in all copies and that both that copyright notice and
49  * this permission notice appear in supporting documentation, and that
50  * the name of FundsXpress. not be used in advertising or publicity pertaining
51  * to distribution of the software without specific, written prior
52  * permission.  FundsXpress makes no representations about the suitability of
53  * this software for any purpose.  It is provided "as is" without express
54  * or implied warranty.
55  *
56  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
57  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
58  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
59  */
60 
61 #include <linux/types.h>
62 #include <linux/jiffies.h>
63 #include <linux/sunrpc/gss_krb5.h>
64 #include <linux/random.h>
65 #include <linux/crypto.h>
66 #include <linux/atomic.h>
67 
68 #include "gss_krb5_internal.h"
69 
70 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
71 # define RPCDBG_FACILITY        RPCDBG_AUTH
72 #endif
73 
74 static void *
75 setup_token_v2(struct krb5_ctx *ctx, struct xdr_netobj *token)
76 {
77 	u16 *ptr;
78 	void *krb5_hdr;
79 	u8 *p, flags = 0x00;
80 
81 	if ((ctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0)
82 		flags |= 0x01;
83 	if (ctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY)
84 		flags |= 0x04;
85 
86 	/* Per rfc 4121, sec 4.2.6.1, there is no header,
87 	 * just start the token.
88 	 */
89 	krb5_hdr = (u16 *)token->data;
90 	ptr = krb5_hdr;
91 
92 	*ptr++ = KG2_TOK_MIC;
93 	p = (u8 *)ptr;
94 	*p++ = flags;
95 	*p++ = 0xff;
96 	ptr = (u16 *)p;
97 	*ptr++ = 0xffff;
98 	*ptr = 0xffff;
99 
100 	token->len = GSS_KRB5_TOK_HDR_LEN + ctx->gk5e->cksumlength;
101 	return krb5_hdr;
102 }
103 
104 u32
105 gss_krb5_get_mic_v2(struct krb5_ctx *ctx, struct xdr_buf *text,
106 		    struct xdr_netobj *token)
107 {
108 	struct crypto_ahash *tfm = ctx->initiate ?
109 				   ctx->initiator_sign : ctx->acceptor_sign;
110 	struct xdr_netobj cksumobj = {
111 		.len =	ctx->gk5e->cksumlength,
112 	};
113 	__be64 seq_send_be64;
114 	void *krb5_hdr;
115 	time64_t now;
116 
117 	dprintk("RPC:       %s\n", __func__);
118 
119 	krb5_hdr = setup_token_v2(ctx, token);
120 
121 	/* Set up the sequence number. Now 64-bits in clear
122 	 * text and w/o direction indicator */
123 	seq_send_be64 = cpu_to_be64(atomic64_fetch_inc(&ctx->seq_send64));
124 	memcpy(krb5_hdr + 8, (char *) &seq_send_be64, 8);
125 
126 	cksumobj.data = krb5_hdr + GSS_KRB5_TOK_HDR_LEN;
127 	if (gss_krb5_checksum(tfm, krb5_hdr, GSS_KRB5_TOK_HDR_LEN,
128 			      text, 0, &cksumobj))
129 		return GSS_S_FAILURE;
130 
131 	now = ktime_get_real_seconds();
132 	return (ctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
133 }
134