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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Cache manager security.
3 *
4 * Copyright (C) 2025 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells ([email protected])
6 */
7
8#include <linux/slab.h>
9#include <crypto/krb5.h>
10#include "internal.h"
11#include "afs_cm.h"
12#include "afs_fs.h"
13#include "protocol_yfs.h"
14#define RXRPC_TRACE_ONLY_DEFINE_ENUMS
15#include <trace/events/rxrpc.h>
16
17#define RXGK_SERVER_ENC_TOKEN 1036U // 0x40c
18#define xdr_round_up(x) (round_up((x), sizeof(__be32)))
19#define xdr_len_object(x) (4 + round_up((x), sizeof(__be32)))
20
21#ifdef CONFIG_RXGK
22static int afs_create_yfs_cm_token(struct sk_buff *challenge,
23 struct afs_server *server);
24#endif
25
26/*
27 * Respond to an RxGK challenge, adding appdata.
28 */
29static int afs_respond_to_challenge(struct sk_buff *challenge)
30{
31#ifdef CONFIG_RXGK
32 struct krb5_buffer appdata = {};
33 struct afs_server *server;
34#endif
35 struct rxrpc_peer *peer;
36 unsigned long peer_data;
37 u16 service_id;
38 u8 security_index;
39
40 rxrpc_kernel_query_challenge(challenge, &peer, &peer_data,
41 &service_id, &security_index);
42
43 _enter("%u,%u", service_id, security_index);
44
45 switch (service_id) {
46 /* We don't send CM_SERVICE RPCs, so don't expect a challenge
47 * therefrom.
48 */
49 case FS_SERVICE:
50 case VL_SERVICE:
51 case YFS_FS_SERVICE:
52 case YFS_VL_SERVICE:
53 break;
54 default:
55 pr_warn("Can't respond to unknown challenge %u:%u",
56 service_id, security_index);
57 return rxrpc_kernel_reject_challenge(challenge, RX_USER_ABORT, -EPROTO,
58 afs_abort_unsupported_sec_class);
59 }
60
61 switch (security_index) {
62#ifdef CONFIG_RXKAD
63 case RXRPC_SECURITY_RXKAD:
64 return rxkad_kernel_respond_to_challenge(challenge);
65#endif
66
67#ifdef CONFIG_RXGK
68 case RXRPC_SECURITY_RXGK:
69 return rxgk_kernel_respond_to_challenge(challenge, &appdata);
70
71 case RXRPC_SECURITY_YFS_RXGK:
72 switch (service_id) {
73 case FS_SERVICE:
74 case YFS_FS_SERVICE:
75 server = (struct afs_server *)peer_data;
76 if (!server->cm_rxgk_appdata.data) {
77 mutex_lock(&server->cm_token_lock);
78 if (!server->cm_rxgk_appdata.data)
79 afs_create_yfs_cm_token(challenge, server);
80 mutex_unlock(&server->cm_token_lock);
81 }
82 if (server->cm_rxgk_appdata.data)
83 appdata = server->cm_rxgk_appdata;
84 break;
85 }
86 return rxgk_kernel_respond_to_challenge(challenge, &appdata);
87#endif
88
89 default:
90 return rxrpc_kernel_reject_challenge(challenge, RX_USER_ABORT, -EPROTO,
91 afs_abort_unsupported_sec_class);
92 }
93}
94
95/*
96 * Process the OOB message queue, processing challenge packets.
97 */
98void afs_process_oob_queue(struct work_struct *work)
99{
100 struct afs_net *net = container_of(work, struct afs_net, rx_oob_work);
101 struct sk_buff *oob;
102 enum rxrpc_oob_type type;
103
104 while (READ_ONCE(net->live) &&
105 (oob = rxrpc_kernel_dequeue_oob(net->socket, &type))) {
106 switch (type) {
107 case RXRPC_OOB_CHALLENGE:
108 afs_respond_to_challenge(oob);
109 break;
110 }
111 rxrpc_kernel_free_oob(oob);
112 }
113}
114
115#ifdef CONFIG_RXGK
116/*
117 * Create a securities keyring for the cache manager and attach a key to it for
118 * the RxGK tokens we want to use to secure the callback connection back from
119 * the fileserver.
120 */
121int afs_create_token_key(struct afs_net *net, struct socket *socket)
122{
123 const struct krb5_enctype *krb5;
124 struct key *ring;
125 key_ref_t key;
126 char K0[32], *desc;
127 int ret;
128
129 ring = keyring_alloc("kafs",
130 GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(),
131 KEY_POS_SEARCH | KEY_POS_WRITE |
132 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH,
133 KEY_ALLOC_NOT_IN_QUOTA,
134 NULL, NULL);
135 if (IS_ERR(ring))
136 return PTR_ERR(ring);
137
138 ret = rxrpc_sock_set_security_keyring(socket->sk, ring);
139 if (ret < 0)
140 goto out;
141
142 ret = -ENOPKG;
143 krb5 = crypto_krb5_find_enctype(KRB5_ENCTYPE_AES128_CTS_HMAC_SHA1_96);
144 if (!krb5)
145 goto out;
146
147 if (WARN_ON_ONCE(krb5->key_len > sizeof(K0)))
148 goto out;
149
150 ret = -ENOMEM;
151 desc = kasprintf(GFP_KERNEL, "%u:%u:%u:%u",
152 YFS_CM_SERVICE, RXRPC_SECURITY_YFS_RXGK, 1, krb5->etype);
153 if (!desc)
154 goto out;
155
156 wait_for_random_bytes();
157 get_random_bytes(K0, krb5->key_len);
158
159 key = key_create(make_key_ref(ring, true),
160 "rxrpc_s", desc,
161 K0, krb5->key_len,
162 KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH | KEY_USR_VIEW,
163 KEY_ALLOC_NOT_IN_QUOTA);
164 kfree(desc);
165 if (IS_ERR(key)) {
166 ret = PTR_ERR(key);
167 goto out;
168 }
169
170 net->fs_cm_token_key = key_ref_to_ptr(key);
171 ret = 0;
172out:
173 key_put(ring);
174 return ret;
175}
176
177/*
178 * Create an YFS RxGK GSS token to use as a ticket to the specified fileserver.
179 */
180static int afs_create_yfs_cm_token(struct sk_buff *challenge,
181 struct afs_server *server)
182{
183 const struct krb5_enctype *conn_krb5, *token_krb5;
184 const struct krb5_buffer *token_key;
185 struct crypto_aead *aead;
186 struct scatterlist sg;
187 struct afs_net *net = server->cell->net;
188 const struct key *key = net->fs_cm_token_key;
189 size_t keysize, uuidsize, authsize, toksize, encsize, contsize, adatasize, offset;
190 __be32 caps[1] = {
191 [0] = htonl(AFS_CAP_ERROR_TRANSLATION),
192 };
193 __be32 *xdr;
194 void *appdata, *K0, *encbase;
195 u32 enctype;
196 int ret;
197
198 if (!key)
199 return -ENOKEY;
200
201 /* Assume that the fileserver is happy to use the same encoding type as
202 * we were told to use by the token obtained by the user.
203 */
204 enctype = rxgk_kernel_query_challenge(challenge);
205
206 conn_krb5 = crypto_krb5_find_enctype(enctype);
207 if (!conn_krb5)
208 return -ENOPKG;
209 token_krb5 = key->payload.data[0];
210 token_key = (const struct krb5_buffer *)&key->payload.data[2];
211
212 /* struct rxgk_key {
213 * afs_uint32 enctype;
214 * opaque key<>;
215 * };
216 */
217 keysize = 4 + xdr_len_object(conn_krb5->key_len);
218
219 /* struct RXGK_AuthName {
220 * afs_int32 kind;
221 * opaque data<AUTHDATAMAX>;
222 * opaque display<AUTHPRINTABLEMAX>;
223 * };
224 */
225 uuidsize = sizeof(server->uuid);
226 authsize = 4 + xdr_len_object(uuidsize) + xdr_len_object(0);
227
228 /* struct RXGK_Token {
229 * rxgk_key K0;
230 * RXGK_Level level;
231 * rxgkTime starttime;
232 * afs_int32 lifetime;
233 * afs_int32 bytelife;
234 * rxgkTime expirationtime;
235 * struct RXGK_AuthName identities<>;
236 * };
237 */
238 toksize = keysize + 8 + 4 + 4 + 8 + xdr_len_object(authsize);
239
240 offset = 0;
241 encsize = crypto_krb5_how_much_buffer(token_krb5, KRB5_ENCRYPT_MODE, toksize, &offset);
242
243 /* struct RXGK_TokenContainer {
244 * afs_int32 kvno;
245 * afs_int32 enctype;
246 * opaque encrypted_token<>;
247 * };
248 */
249 contsize = 4 + 4 + xdr_len_object(encsize);
250
251 /* struct YFSAppData {
252 * opr_uuid initiatorUuid;
253 * opr_uuid acceptorUuid;
254 * Capabilities caps;
255 * afs_int32 enctype;
256 * opaque callbackKey<>;
257 * opaque callbackToken<>;
258 * };
259 */
260 adatasize = 16 + 16 +
261 xdr_len_object(sizeof(caps)) +
262 4 +
263 xdr_len_object(conn_krb5->key_len) +
264 xdr_len_object(contsize);
265
266 ret = -ENOMEM;
267 appdata = kzalloc(adatasize, GFP_KERNEL);
268 if (!appdata)
269 goto out;
270 xdr = appdata;
271
272 memcpy(xdr, &net->uuid, 16); /* appdata.initiatorUuid */
273 xdr += 16 / 4;
274 memcpy(xdr, &server->uuid, 16); /* appdata.acceptorUuid */
275 xdr += 16 / 4;
276 *xdr++ = htonl(ARRAY_SIZE(caps)); /* appdata.caps.len */
277 memcpy(xdr, &caps, sizeof(caps)); /* appdata.caps */
278 xdr += ARRAY_SIZE(caps);
279 *xdr++ = htonl(conn_krb5->etype); /* appdata.enctype */
280
281 *xdr++ = htonl(conn_krb5->key_len); /* appdata.callbackKey.len */
282 K0 = xdr;
283 get_random_bytes(K0, conn_krb5->key_len); /* appdata.callbackKey.data */
284 xdr += xdr_round_up(conn_krb5->key_len) / 4;
285
286 *xdr++ = htonl(contsize); /* appdata.callbackToken.len */
287 *xdr++ = htonl(1); /* cont.kvno */
288 *xdr++ = htonl(token_krb5->etype); /* cont.enctype */
289 *xdr++ = htonl(encsize); /* cont.encrypted_token.len */
290
291 encbase = xdr;
292 xdr += offset / 4;
293 *xdr++ = htonl(conn_krb5->etype); /* token.K0.enctype */
294 *xdr++ = htonl(conn_krb5->key_len); /* token.K0.key.len */
295 memcpy(xdr, K0, conn_krb5->key_len); /* token.K0.key.data */
296 xdr += xdr_round_up(conn_krb5->key_len) / 4;
297
298 *xdr++ = htonl(RXRPC_SECURITY_ENCRYPT); /* token.level */
299 *xdr++ = htonl(0); /* token.starttime */
300 *xdr++ = htonl(0); /* " */
301 *xdr++ = htonl(0); /* token.lifetime */
302 *xdr++ = htonl(0); /* token.bytelife */
303 *xdr++ = htonl(0); /* token.expirationtime */
304 *xdr++ = htonl(0); /* " */
305 *xdr++ = htonl(1); /* token.identities.count */
306 *xdr++ = htonl(0); /* token.identities[0].kind */
307 *xdr++ = htonl(uuidsize); /* token.identities[0].data.len */
308 memcpy(xdr, &server->uuid, uuidsize);
309 xdr += xdr_round_up(uuidsize) / 4;
310 *xdr++ = htonl(0); /* token.identities[0].display.len */
311
312 xdr = encbase + xdr_round_up(encsize);
313
314 if ((unsigned long)xdr - (unsigned long)appdata != adatasize)
315 pr_err("Appdata size incorrect %lx != %zx\n",
316 (unsigned long)xdr - (unsigned long)appdata, adatasize);
317
318 aead = crypto_krb5_prepare_encryption(token_krb5, token_key, RXGK_SERVER_ENC_TOKEN,
319 GFP_KERNEL);
320 if (IS_ERR(aead)) {
321 ret = PTR_ERR(aead);
322 goto out_token;
323 }
324
325 sg_init_one(&sg, encbase, encsize);
326 ret = crypto_krb5_encrypt(token_krb5, aead, &sg, 1, encsize, offset, toksize, false);
327 if (ret < 0)
328 goto out_aead;
329
330 server->cm_rxgk_appdata.len = adatasize;
331 server->cm_rxgk_appdata.data = appdata;
332 appdata = NULL;
333
334out_aead:
335 crypto_free_aead(aead);
336out_token:
337 kfree(appdata);
338out:
339 return ret;
340}
341#endif /* CONFIG_RXGK */