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1 /*
2  *  linux/net/sunrpc/gss_spkm3_seal.c
3  *
4  *  Copyright (c) 2003 The Regents of the University of Michigan.
5  *  All rights reserved.
6  *
7  *  Andy Adamson <andros@umich.edu>
8  *
9  *  Redistribution and use in source and binary forms, with or without
10  *  modification, are permitted provided that the following conditions
11  *  are met:
12  *
13  *  1. Redistributions of source code must retain the above copyright
14  *     notice, this list of conditions and the following disclaimer.
15  *  2. Redistributions in binary form must reproduce the above copyright
16  *     notice, this list of conditions and the following disclaimer in the
17  *     documentation and/or other materials provided with the distribution.
18  *  3. Neither the name of the University nor the names of its
19  *     contributors may be used to endorse or promote products derived
20  *     from this software without specific prior written permission.
21  *
22  *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
23  *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
24  *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
25  *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
27  *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
28  *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
29  *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
30  *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
31  *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
32  *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33  *
34  */
35 
36 #include <linux/types.h>
37 #include <linux/slab.h>
38 #include <linux/jiffies.h>
39 #include <linux/sunrpc/gss_spkm3.h>
40 #include <linux/random.h>
41 #include <linux/crypto.h>
42 #include <linux/pagemap.h>
43 #include <linux/scatterlist.h>
44 #include <linux/sunrpc/xdr.h>
45 
46 #ifdef RPC_DEBUG
47 # define RPCDBG_FACILITY        RPCDBG_AUTH
48 #endif
49 
50 const struct xdr_netobj hmac_md5_oid = { 8, "\x2B\x06\x01\x05\x05\x08\x01\x01"};
51 const struct xdr_netobj cast5_cbc_oid = {9, "\x2A\x86\x48\x86\xF6\x7D\x07\x42\x0A"};
52 
53 /*
54  * spkm3_make_token()
55  *
56  * Only SPKM_MIC_TOK with md5 intg-alg is supported
57  */
58 
59 u32
spkm3_make_token(struct spkm3_ctx * ctx,struct xdr_buf * text,struct xdr_netobj * token,int toktype)60 spkm3_make_token(struct spkm3_ctx *ctx,
61 		   struct xdr_buf * text, struct xdr_netobj * token,
62 		   int toktype)
63 {
64 	s32			checksum_type;
65 	char			tokhdrbuf[25];
66 	char			cksumdata[16];
67 	struct xdr_netobj	md5cksum = {.len = 0, .data = cksumdata};
68 	struct xdr_netobj	mic_hdr = {.len = 0, .data = tokhdrbuf};
69 	int			tokenlen = 0;
70 	unsigned char		*ptr;
71 	s32			now;
72 	int			ctxelen = 0, ctxzbit = 0;
73 	int			md5elen = 0, md5zbit = 0;
74 
75 	now = jiffies;
76 
77 	if (ctx->ctx_id.len != 16) {
78 		dprintk("RPC:       spkm3_make_token BAD ctx_id.len %d\n",
79 				ctx->ctx_id.len);
80 		goto out_err;
81 	}
82 
83 	if (!g_OID_equal(&ctx->intg_alg, &hmac_md5_oid)) {
84 		dprintk("RPC:       gss_spkm3_seal: unsupported I-ALG "
85 				"algorithm.  only support hmac-md5 I-ALG.\n");
86 		goto out_err;
87 	} else
88 		checksum_type = CKSUMTYPE_HMAC_MD5;
89 
90 	if (!g_OID_equal(&ctx->conf_alg, &cast5_cbc_oid)) {
91 		dprintk("RPC:       gss_spkm3_seal: unsupported C-ALG "
92 				"algorithm\n");
93 		goto out_err;
94 	}
95 
96 	if (toktype == SPKM_MIC_TOK) {
97 		/* Calculate checksum over the mic-header */
98 		asn1_bitstring_len(&ctx->ctx_id, &ctxelen, &ctxzbit);
99 		spkm3_mic_header(&mic_hdr.data, &mic_hdr.len, ctx->ctx_id.data,
100 				ctxelen, ctxzbit);
101 		if (make_spkm3_checksum(checksum_type, &ctx->derived_integ_key,
102 					(char *)mic_hdr.data, mic_hdr.len,
103 					text, 0, &md5cksum))
104 			goto out_err;
105 
106 		asn1_bitstring_len(&md5cksum, &md5elen, &md5zbit);
107 		tokenlen = 10 + ctxelen + 1 + md5elen + 1;
108 
109 		/* Create token header using generic routines */
110 		token->len = g_token_size(&ctx->mech_used, tokenlen + 2);
111 
112 		ptr = token->data;
113 		g_make_token_header(&ctx->mech_used, tokenlen + 2, &ptr);
114 
115 		spkm3_make_mic_token(&ptr, tokenlen, &mic_hdr, &md5cksum, md5elen, md5zbit);
116 	} else if (toktype == SPKM_WRAP_TOK) { /* Not Supported */
117 		dprintk("RPC:       gss_spkm3_seal: SPKM_WRAP_TOK "
118 				"not supported\n");
119 		goto out_err;
120 	}
121 
122 	/* XXX need to implement sequence numbers, and ctx->expired */
123 
124 	return  GSS_S_COMPLETE;
125 out_err:
126 	token->data = NULL;
127 	token->len = 0;
128 	return GSS_S_FAILURE;
129 }
130 
131 static int
spkm3_checksummer(struct scatterlist * sg,void * data)132 spkm3_checksummer(struct scatterlist *sg, void *data)
133 {
134 	struct hash_desc *desc = data;
135 
136 	return crypto_hash_update(desc, sg, sg->length);
137 }
138 
139 /* checksum the plaintext data and hdrlen bytes of the token header */
140 s32
make_spkm3_checksum(s32 cksumtype,struct xdr_netobj * key,char * header,unsigned int hdrlen,struct xdr_buf * body,unsigned int body_offset,struct xdr_netobj * cksum)141 make_spkm3_checksum(s32 cksumtype, struct xdr_netobj *key, char *header,
142 		    unsigned int hdrlen, struct xdr_buf *body,
143 		    unsigned int body_offset, struct xdr_netobj *cksum)
144 {
145 	char				*cksumname;
146 	struct hash_desc		desc; /* XXX add to ctx? */
147 	struct scatterlist		sg[1];
148 	int err;
149 
150 	switch (cksumtype) {
151 		case CKSUMTYPE_HMAC_MD5:
152 			cksumname = "hmac(md5)";
153 			break;
154 		default:
155 			dprintk("RPC:       spkm3_make_checksum:"
156 					" unsupported checksum %d", cksumtype);
157 			return GSS_S_FAILURE;
158 	}
159 
160 	if (key->data == NULL || key->len <= 0) return GSS_S_FAILURE;
161 
162 	desc.tfm = crypto_alloc_hash(cksumname, 0, CRYPTO_ALG_ASYNC);
163 	if (IS_ERR(desc.tfm))
164 		return GSS_S_FAILURE;
165 	cksum->len = crypto_hash_digestsize(desc.tfm);
166 	desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
167 
168 	err = crypto_hash_setkey(desc.tfm, key->data, key->len);
169 	if (err)
170 		goto out;
171 
172 	err = crypto_hash_init(&desc);
173 	if (err)
174 		goto out;
175 
176 	sg_init_one(sg, header, hdrlen);
177 	crypto_hash_update(&desc, sg, sg->length);
178 
179 	xdr_process_buf(body, body_offset, body->len - body_offset,
180 			spkm3_checksummer, &desc);
181 	crypto_hash_final(&desc, cksum->data);
182 
183 out:
184 	crypto_free_hash(desc.tfm);
185 
186 	return err ? GSS_S_FAILURE : 0;
187 }
188