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 #if defined(CONFIG_RPCSEC_GSS_KRB5_SIMPLIFIED)
75 
76 static void *
77 setup_token(struct krb5_ctx *ctx, struct xdr_netobj *token)
78 {
79 	u16 *ptr;
80 	void *krb5_hdr;
81 	int body_size = GSS_KRB5_TOK_HDR_LEN + ctx->gk5e->cksumlength;
82 
83 	token->len = g_token_size(&ctx->mech_used, body_size);
84 
85 	ptr = (u16 *)token->data;
86 	g_make_token_header(&ctx->mech_used, body_size, (unsigned char **)&ptr);
87 
88 	/* ptr now at start of header described in rfc 1964, section 1.2.1: */
89 	krb5_hdr = ptr;
90 	*ptr++ = KG_TOK_MIC_MSG;
91 	/*
92 	 * signalg is stored as if it were converted from LE to host endian, even
93 	 * though it's an opaque pair of bytes according to the RFC.
94 	 */
95 	*ptr++ = (__force u16)cpu_to_le16(ctx->gk5e->signalg);
96 	*ptr++ = SEAL_ALG_NONE;
97 	*ptr = 0xffff;
98 
99 	return krb5_hdr;
100 }
101 
102 u32
103 gss_krb5_get_mic_v1(struct krb5_ctx *ctx, struct xdr_buf *text,
104 		    struct xdr_netobj *token)
105 {
106 	char			cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
107 	struct xdr_netobj	md5cksum = {.len = sizeof(cksumdata),
108 					    .data = cksumdata};
109 	void			*ptr;
110 	time64_t		now;
111 	u32			seq_send;
112 	u8			*cksumkey;
113 
114 	dprintk("RPC:       %s\n", __func__);
115 	BUG_ON(ctx == NULL);
116 
117 	now = ktime_get_real_seconds();
118 
119 	ptr = setup_token(ctx, token);
120 
121 	if (ctx->gk5e->keyed_cksum)
122 		cksumkey = ctx->cksum;
123 	else
124 		cksumkey = NULL;
125 
126 	if (make_checksum(ctx, ptr, 8, text, 0, cksumkey,
127 			  KG_USAGE_SIGN, &md5cksum))
128 		return GSS_S_FAILURE;
129 
130 	memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len);
131 
132 	seq_send = atomic_fetch_inc(&ctx->seq_send);
133 
134 	if (krb5_make_seq_num(ctx, ctx->seq, ctx->initiate ? 0 : 0xff,
135 			      seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8))
136 		return GSS_S_FAILURE;
137 
138 	return (ctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
139 }
140 
141 #endif
142 
143 static void *
144 setup_token_v2(struct krb5_ctx *ctx, struct xdr_netobj *token)
145 {
146 	u16 *ptr;
147 	void *krb5_hdr;
148 	u8 *p, flags = 0x00;
149 
150 	if ((ctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0)
151 		flags |= 0x01;
152 	if (ctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY)
153 		flags |= 0x04;
154 
155 	/* Per rfc 4121, sec 4.2.6.1, there is no header,
156 	 * just start the token.
157 	 */
158 	krb5_hdr = (u16 *)token->data;
159 	ptr = krb5_hdr;
160 
161 	*ptr++ = KG2_TOK_MIC;
162 	p = (u8 *)ptr;
163 	*p++ = flags;
164 	*p++ = 0xff;
165 	ptr = (u16 *)p;
166 	*ptr++ = 0xffff;
167 	*ptr = 0xffff;
168 
169 	token->len = GSS_KRB5_TOK_HDR_LEN + ctx->gk5e->cksumlength;
170 	return krb5_hdr;
171 }
172 
173 u32
174 gss_krb5_get_mic_v2(struct krb5_ctx *ctx, struct xdr_buf *text,
175 		    struct xdr_netobj *token)
176 {
177 	struct crypto_ahash *tfm = ctx->initiate ?
178 				   ctx->initiator_sign : ctx->acceptor_sign;
179 	struct xdr_netobj cksumobj = {
180 		.len =	ctx->gk5e->cksumlength,
181 	};
182 	__be64 seq_send_be64;
183 	void *krb5_hdr;
184 	time64_t now;
185 
186 	dprintk("RPC:       %s\n", __func__);
187 
188 	krb5_hdr = setup_token_v2(ctx, token);
189 
190 	/* Set up the sequence number. Now 64-bits in clear
191 	 * text and w/o direction indicator */
192 	seq_send_be64 = cpu_to_be64(atomic64_fetch_inc(&ctx->seq_send64));
193 	memcpy(krb5_hdr + 8, (char *) &seq_send_be64, 8);
194 
195 	cksumobj.data = krb5_hdr + GSS_KRB5_TOK_HDR_LEN;
196 	if (gss_krb5_checksum(tfm, krb5_hdr, GSS_KRB5_TOK_HDR_LEN,
197 			      text, 0, &cksumobj))
198 		return GSS_S_FAILURE;
199 
200 	now = ktime_get_real_seconds();
201 	return (ctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
202 }
203