1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * The ASB.1/BER parsing code is derived from ip_nat_snmp_basic.c which was in
4 * turn derived from the gxsnmp package by Gregory McLean & Jochen Friedrich
5 *
6 * Copyright (c) 2000 RP Internet (www.rpi.net.au).
7 */
8
9 #include <linux/module.h>
10 #include <linux/types.h>
11 #include <linux/kernel.h>
12 #include <linux/mm.h>
13 #include <linux/slab.h>
14 #include <linux/oid_registry.h>
15
16 #include "glob.h"
17
18 #include "asn1.h"
19 #include "connection.h"
20 #include "auth.h"
21 #include "ksmbd_spnego_negtokeninit.asn1.h"
22 #include "ksmbd_spnego_negtokentarg.asn1.h"
23
24 #define NTLMSSP_OID_LEN 10
25
26 static char NTLMSSP_OID_STR[NTLMSSP_OID_LEN] = { 0x2b, 0x06, 0x01, 0x04, 0x01,
27 0x82, 0x37, 0x02, 0x02, 0x0a };
28
29 int
30 ksmbd_decode_negTokenInit(unsigned char *security_blob, int length,
31 struct ksmbd_conn *conn)
32 {
33 return asn1_ber_decoder(&ksmbd_spnego_negtokeninit_decoder, conn,
34 security_blob, length);
35 }
36
37 int
38 ksmbd_decode_negTokenTarg(unsigned char *security_blob, int length,
39 struct ksmbd_conn *conn)
40 {
41 return asn1_ber_decoder(&ksmbd_spnego_negtokentarg_decoder, conn,
42 security_blob, length);
43 }
44
45 static int compute_asn_hdr_len_bytes(int len)
46 {
47 if (len > 0xFFFFFF)
48 return 4;
49 else if (len > 0xFFFF)
50 return 3;
51 else if (len > 0xFF)
52 return 2;
53 else if (len > 0x7F)
54 return 1;
55 else
56 return 0;
57 }
58
59 static void encode_asn_tag(char *buf, unsigned int *ofs, char tag, char seq,
60 int length)
61 {
62 int i;
63 int index = *ofs;
64 char hdr_len = compute_asn_hdr_len_bytes(length);
65 int len = length + 2 + hdr_len;
66
67 /* insert tag */
68 buf[index++] = tag;
69
70 if (!hdr_len) {
71 buf[index++] = len;
72 } else {
73 buf[index++] = 0x80 | hdr_len;
74 for (i = hdr_len - 1; i >= 0; i--)
75 buf[index++] = (len >> (i * 8)) & 0xFF;
76 }
77
78 /* insert seq */
79 len = len - (index - *ofs);
80 buf[index++] = seq;
81
82 if (!hdr_len) {
83 buf[index++] = len;
84 } else {
85 buf[index++] = 0x80 | hdr_len;
86 for (i = hdr_len - 1; i >= 0; i--)
87 buf[index++] = (len >> (i * 8)) & 0xFF;
88 }
89
90 *ofs += (index - *ofs);
91 }
92
93 int build_spnego_ntlmssp_neg_blob(unsigned char **pbuffer, u16 *buflen,
94 char *ntlm_blob, int ntlm_blob_len)
95 {
96 char *buf;
97 unsigned int ofs = 0;
98 int neg_result_len = 4 + compute_asn_hdr_len_bytes(1) * 2 + 1;
99 int oid_len = 4 + compute_asn_hdr_len_bytes(NTLMSSP_OID_LEN) * 2 +
100 NTLMSSP_OID_LEN;
101 int ntlmssp_len = 4 + compute_asn_hdr_len_bytes(ntlm_blob_len) * 2 +
102 ntlm_blob_len;
103 int total_len = 4 + compute_asn_hdr_len_bytes(neg_result_len +
104 oid_len + ntlmssp_len) * 2 +
105 neg_result_len + oid_len + ntlmssp_len;
106
107 buf = kmalloc(total_len, GFP_KERNEL);
108 if (!buf)
109 return -ENOMEM;
110
111 /* insert main gss header */
112 encode_asn_tag(buf, &ofs, 0xa1, 0x30, neg_result_len + oid_len +
113 ntlmssp_len);
114
115 /* insert neg result */
116 encode_asn_tag(buf, &ofs, 0xa0, 0x0a, 1);
117 buf[ofs++] = 1;
118
119 /* insert oid */
120 encode_asn_tag(buf, &ofs, 0xa1, 0x06, NTLMSSP_OID_LEN);
121 memcpy(buf + ofs, NTLMSSP_OID_STR, NTLMSSP_OID_LEN);
122 ofs += NTLMSSP_OID_LEN;
123
124 /* insert response token - ntlmssp blob */
125 encode_asn_tag(buf, &ofs, 0xa2, 0x04, ntlm_blob_len);
126 memcpy(buf + ofs, ntlm_blob, ntlm_blob_len);
127 ofs += ntlm_blob_len;
128
129 *pbuffer = buf;
130 *buflen = total_len;
131 return 0;
132 }
133
134 int build_spnego_ntlmssp_auth_blob(unsigned char **pbuffer, u16 *buflen,
135 int neg_result)
136 {
137 char *buf;
138 unsigned int ofs = 0;
139 int neg_result_len = 4 + compute_asn_hdr_len_bytes(1) * 2 + 1;
140 int total_len = 4 + compute_asn_hdr_len_bytes(neg_result_len) * 2 +
141 neg_result_len;
142
143 buf = kmalloc(total_len, GFP_KERNEL);
144 if (!buf)
145 return -ENOMEM;
146
147 /* insert main gss header */
148 encode_asn_tag(buf, &ofs, 0xa1, 0x30, neg_result_len);
149
150 /* insert neg result */
151 encode_asn_tag(buf, &ofs, 0xa0, 0x0a, 1);
152 if (neg_result)
153 buf[ofs++] = 2;
154 else
155 buf[ofs++] = 0;
156
157 *pbuffer = buf;
158 *buflen = total_len;
159 return 0;
160 }
161
162 int ksmbd_gssapi_this_mech(void *context, size_t hdrlen, unsigned char tag,
163 const void *value, size_t vlen)
164 {
165 enum OID oid;
166
167 oid = look_up_OID(value, vlen);
168 if (oid != OID_spnego) {
169 char buf[50];
170
171 sprint_oid(value, vlen, buf, sizeof(buf));
172 ksmbd_debug(AUTH, "Unexpected OID: %s\n", buf);
173 return -EBADMSG;
174 }
175
176 return 0;
177 }
178
179 int ksmbd_neg_token_init_mech_type(void *context, size_t hdrlen,
180 unsigned char tag, const void *value,
181 size_t vlen)
182 {
183 struct ksmbd_conn *conn = context;
184 enum OID oid;
185 int mech_type;
186
187 oid = look_up_OID(value, vlen);
188 if (oid == OID_ntlmssp) {
189 mech_type = KSMBD_AUTH_NTLMSSP;
190 } else if (oid == OID_mskrb5) {
191 mech_type = KSMBD_AUTH_MSKRB5;
192 } else if (oid == OID_krb5) {
193 mech_type = KSMBD_AUTH_KRB5;
194 } else if (oid == OID_krb5u2u) {
195 mech_type = KSMBD_AUTH_KRB5U2U;
196 } else {
197 char buf[50];
198
199 sprint_oid(value, vlen, buf, sizeof(buf));
200 ksmbd_debug(AUTH, "Unexpected OID: %s\n", buf);
201 return -EBADMSG;
202 }
203
204 conn->auth_mechs |= mech_type;
205 if (conn->preferred_auth_mech == 0)
206 conn->preferred_auth_mech = mech_type;
207
208 return 0;
209 }
210
211 static int ksmbd_neg_token_alloc(void *context, size_t hdrlen,
212 unsigned char tag, const void *value,
213 size_t vlen)
214 {
215 struct ksmbd_conn *conn = context;
216
217 if (!vlen)
218 return -EINVAL;
219
220 conn->mechToken = kmemdup_nul(value, vlen, GFP_KERNEL);
221 if (!conn->mechToken)
222 return -ENOMEM;
223
224 conn->mechTokenLen = (unsigned int)vlen;
225
226 return 0;
227 }
228
229 int ksmbd_neg_token_init_mech_token(void *context, size_t hdrlen,
230 unsigned char tag, const void *value,
231 size_t vlen)
232 {
233 return ksmbd_neg_token_alloc(context, hdrlen, tag, value, vlen);
234 }
235
236 int ksmbd_neg_token_targ_resp_token(void *context, size_t hdrlen,
237 unsigned char tag, const void *value,
238 size_t vlen)
239 {
240 return ksmbd_neg_token_alloc(context, hdrlen, tag, value, vlen);
241 }
242
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