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1 /*
2  *  linux/net/sunrpc/gss_krb5_seqnum.c
3  *
4  *  Adapted from MIT Kerberos 5-1.2.1 lib/gssapi/krb5/util_seqnum.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 #include <crypto/skcipher.h>
35 #include <linux/types.h>
36 #include <linux/sunrpc/gss_krb5.h>
37 
38 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
39 # define RPCDBG_FACILITY        RPCDBG_AUTH
40 #endif
41 
42 static s32
krb5_make_rc4_seq_num(struct krb5_ctx * kctx,int direction,s32 seqnum,unsigned char * cksum,unsigned char * buf)43 krb5_make_rc4_seq_num(struct krb5_ctx *kctx, int direction, s32 seqnum,
44 		      unsigned char *cksum, unsigned char *buf)
45 {
46 	struct crypto_skcipher *cipher;
47 	unsigned char plain[8];
48 	s32 code;
49 
50 	dprintk("RPC:       %s:\n", __func__);
51 	cipher = crypto_alloc_skcipher(kctx->gk5e->encrypt_name, 0,
52 				       CRYPTO_ALG_ASYNC);
53 	if (IS_ERR(cipher))
54 		return PTR_ERR(cipher);
55 
56 	plain[0] = (unsigned char) ((seqnum >> 24) & 0xff);
57 	plain[1] = (unsigned char) ((seqnum >> 16) & 0xff);
58 	plain[2] = (unsigned char) ((seqnum >> 8) & 0xff);
59 	plain[3] = (unsigned char) ((seqnum >> 0) & 0xff);
60 	plain[4] = direction;
61 	plain[5] = direction;
62 	plain[6] = direction;
63 	plain[7] = direction;
64 
65 	code = krb5_rc4_setup_seq_key(kctx, cipher, cksum);
66 	if (code)
67 		goto out;
68 
69 	code = krb5_encrypt(cipher, cksum, plain, buf, 8);
70 out:
71 	crypto_free_skcipher(cipher);
72 	return code;
73 }
74 s32
krb5_make_seq_num(struct krb5_ctx * kctx,struct crypto_skcipher * key,int direction,u32 seqnum,unsigned char * cksum,unsigned char * buf)75 krb5_make_seq_num(struct krb5_ctx *kctx,
76 		struct crypto_skcipher *key,
77 		int direction,
78 		u32 seqnum,
79 		unsigned char *cksum, unsigned char *buf)
80 {
81 	unsigned char plain[8];
82 
83 	if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC)
84 		return krb5_make_rc4_seq_num(kctx, direction, seqnum,
85 					     cksum, buf);
86 
87 	plain[0] = (unsigned char) (seqnum & 0xff);
88 	plain[1] = (unsigned char) ((seqnum >> 8) & 0xff);
89 	plain[2] = (unsigned char) ((seqnum >> 16) & 0xff);
90 	plain[3] = (unsigned char) ((seqnum >> 24) & 0xff);
91 
92 	plain[4] = direction;
93 	plain[5] = direction;
94 	plain[6] = direction;
95 	plain[7] = direction;
96 
97 	return krb5_encrypt(key, cksum, plain, buf, 8);
98 }
99 
100 static s32
krb5_get_rc4_seq_num(struct krb5_ctx * kctx,unsigned char * cksum,unsigned char * buf,int * direction,s32 * seqnum)101 krb5_get_rc4_seq_num(struct krb5_ctx *kctx, unsigned char *cksum,
102 		     unsigned char *buf, int *direction, s32 *seqnum)
103 {
104 	struct crypto_skcipher *cipher;
105 	unsigned char plain[8];
106 	s32 code;
107 
108 	dprintk("RPC:       %s:\n", __func__);
109 	cipher = crypto_alloc_skcipher(kctx->gk5e->encrypt_name, 0,
110 				       CRYPTO_ALG_ASYNC);
111 	if (IS_ERR(cipher))
112 		return PTR_ERR(cipher);
113 
114 	code = krb5_rc4_setup_seq_key(kctx, cipher, cksum);
115 	if (code)
116 		goto out;
117 
118 	code = krb5_decrypt(cipher, cksum, buf, plain, 8);
119 	if (code)
120 		goto out;
121 
122 	if ((plain[4] != plain[5]) || (plain[4] != plain[6])
123 				   || (plain[4] != plain[7])) {
124 		code = (s32)KG_BAD_SEQ;
125 		goto out;
126 	}
127 
128 	*direction = plain[4];
129 
130 	*seqnum = ((plain[0] << 24) | (plain[1] << 16) |
131 					(plain[2] << 8) | (plain[3]));
132 out:
133 	crypto_free_skcipher(cipher);
134 	return code;
135 }
136 
137 s32
krb5_get_seq_num(struct krb5_ctx * kctx,unsigned char * cksum,unsigned char * buf,int * direction,u32 * seqnum)138 krb5_get_seq_num(struct krb5_ctx *kctx,
139 	       unsigned char *cksum,
140 	       unsigned char *buf,
141 	       int *direction, u32 *seqnum)
142 {
143 	s32 code;
144 	unsigned char plain[8];
145 	struct crypto_skcipher *key = kctx->seq;
146 
147 	dprintk("RPC:       krb5_get_seq_num:\n");
148 
149 	if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC)
150 		return krb5_get_rc4_seq_num(kctx, cksum, buf,
151 					    direction, seqnum);
152 
153 	if ((code = krb5_decrypt(key, cksum, buf, plain, 8)))
154 		return code;
155 
156 	if ((plain[4] != plain[5]) || (plain[4] != plain[6]) ||
157 	    (plain[4] != plain[7]))
158 		return (s32)KG_BAD_SEQ;
159 
160 	*direction = plain[4];
161 
162 	*seqnum = ((plain[0]) |
163 		   (plain[1] << 8) | (plain[2] << 16) | (plain[3] << 24));
164 
165 	return 0;
166 }
167