1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *  linux/net/sunrpc/gss_rpc_upcall.c
4  *
5  *  Copyright (C) 2012 Simo Sorce <simo@redhat.com>
6  */
7 
8 #include <linux/types.h>
9 #include <linux/un.h>
10 
11 #include <linux/sunrpc/svcauth.h>
12 #include "gss_rpc_upcall.h"
13 
14 #define GSSPROXY_SOCK_PATHNAME	"/var/run/gssproxy.sock"
15 
16 #define GSSPROXY_PROGRAM	(400112u)
17 #define GSSPROXY_VERS_1		(1u)
18 
19 /*
20  * Encoding/Decoding functions
21  */
22 
23 enum {
24 	GSSX_NULL = 0,	/* Unused */
25         GSSX_INDICATE_MECHS = 1,
26         GSSX_GET_CALL_CONTEXT = 2,
27         GSSX_IMPORT_AND_CANON_NAME = 3,
28         GSSX_EXPORT_CRED = 4,
29         GSSX_IMPORT_CRED = 5,
30         GSSX_ACQUIRE_CRED = 6,
31         GSSX_STORE_CRED = 7,
32         GSSX_INIT_SEC_CONTEXT = 8,
33         GSSX_ACCEPT_SEC_CONTEXT = 9,
34         GSSX_RELEASE_HANDLE = 10,
35         GSSX_GET_MIC = 11,
36         GSSX_VERIFY = 12,
37         GSSX_WRAP = 13,
38         GSSX_UNWRAP = 14,
39         GSSX_WRAP_SIZE_LIMIT = 15,
40 };
41 
42 #define PROC(proc, name)				\
43 [GSSX_##proc] = {					\
44 	.p_proc   = GSSX_##proc,			\
45 	.p_encode = gssx_enc_##name,	\
46 	.p_decode = gssx_dec_##name,	\
47 	.p_arglen = GSSX_ARG_##name##_sz,		\
48 	.p_replen = GSSX_RES_##name##_sz, 		\
49 	.p_statidx = GSSX_##proc,			\
50 	.p_name   = #proc,				\
51 }
52 
53 static const struct rpc_procinfo gssp_procedures[] = {
54 	PROC(INDICATE_MECHS, indicate_mechs),
55         PROC(GET_CALL_CONTEXT, get_call_context),
56         PROC(IMPORT_AND_CANON_NAME, import_and_canon_name),
57         PROC(EXPORT_CRED, export_cred),
58         PROC(IMPORT_CRED, import_cred),
59         PROC(ACQUIRE_CRED, acquire_cred),
60         PROC(STORE_CRED, store_cred),
61         PROC(INIT_SEC_CONTEXT, init_sec_context),
62         PROC(ACCEPT_SEC_CONTEXT, accept_sec_context),
63         PROC(RELEASE_HANDLE, release_handle),
64         PROC(GET_MIC, get_mic),
65         PROC(VERIFY, verify),
66         PROC(WRAP, wrap),
67         PROC(UNWRAP, unwrap),
68         PROC(WRAP_SIZE_LIMIT, wrap_size_limit),
69 };
70 
71 
72 
73 /*
74  * Common transport functions
75  */
76 
77 static const struct rpc_program gssp_program;
78 
79 static int gssp_rpc_create(struct net *net, struct rpc_clnt **_clnt)
80 {
81 	static const struct sockaddr_un gssp_localaddr = {
82 		.sun_family		= AF_LOCAL,
83 		.sun_path		= GSSPROXY_SOCK_PATHNAME,
84 	};
85 	struct rpc_create_args args = {
86 		.net		= net,
87 		.protocol	= XPRT_TRANSPORT_LOCAL,
88 		.address	= (struct sockaddr *)&gssp_localaddr,
89 		.addrsize	= sizeof(gssp_localaddr),
90 		.servername	= "localhost",
91 		.program	= &gssp_program,
92 		.version	= GSSPROXY_VERS_1,
93 		.authflavor	= RPC_AUTH_NULL,
94 		/*
95 		 * Note we want connection to be done in the caller's
96 		 * filesystem namespace.  We therefore turn off the idle
97 		 * timeout, which would result in reconnections being
98 		 * done without the correct namespace:
99 		 */
100 		.flags		= RPC_CLNT_CREATE_NOPING |
101 				  RPC_CLNT_CREATE_NO_IDLE_TIMEOUT
102 	};
103 	struct rpc_clnt *clnt;
104 	int result = 0;
105 
106 	clnt = rpc_create(&args);
107 	if (IS_ERR(clnt)) {
108 		dprintk("RPC:       failed to create AF_LOCAL gssproxy "
109 				"client (errno %ld).\n", PTR_ERR(clnt));
110 		result = PTR_ERR(clnt);
111 		*_clnt = NULL;
112 		goto out;
113 	}
114 
115 	dprintk("RPC:       created new gssp local client (gssp_local_clnt: "
116 			"%p)\n", clnt);
117 	*_clnt = clnt;
118 
119 out:
120 	return result;
121 }
122 
123 void init_gssp_clnt(struct sunrpc_net *sn)
124 {
125 	mutex_init(&sn->gssp_lock);
126 	sn->gssp_clnt = NULL;
127 }
128 
129 int set_gssp_clnt(struct net *net)
130 {
131 	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
132 	struct rpc_clnt *clnt;
133 	int ret;
134 
135 	mutex_lock(&sn->gssp_lock);
136 	ret = gssp_rpc_create(net, &clnt);
137 	if (!ret) {
138 		if (sn->gssp_clnt)
139 			rpc_shutdown_client(sn->gssp_clnt);
140 		sn->gssp_clnt = clnt;
141 	}
142 	mutex_unlock(&sn->gssp_lock);
143 	return ret;
144 }
145 
146 void clear_gssp_clnt(struct sunrpc_net *sn)
147 {
148 	mutex_lock(&sn->gssp_lock);
149 	if (sn->gssp_clnt) {
150 		rpc_shutdown_client(sn->gssp_clnt);
151 		sn->gssp_clnt = NULL;
152 	}
153 	mutex_unlock(&sn->gssp_lock);
154 }
155 
156 static struct rpc_clnt *get_gssp_clnt(struct sunrpc_net *sn)
157 {
158 	struct rpc_clnt *clnt;
159 
160 	mutex_lock(&sn->gssp_lock);
161 	clnt = sn->gssp_clnt;
162 	if (clnt)
163 		atomic_inc(&clnt->cl_count);
164 	mutex_unlock(&sn->gssp_lock);
165 	return clnt;
166 }
167 
168 static int gssp_call(struct net *net, struct rpc_message *msg)
169 {
170 	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
171 	struct rpc_clnt *clnt;
172 	int status;
173 
174 	clnt = get_gssp_clnt(sn);
175 	if (!clnt)
176 		return -EIO;
177 	status = rpc_call_sync(clnt, msg, 0);
178 	if (status < 0) {
179 		dprintk("gssp: rpc_call returned error %d\n", -status);
180 		switch (status) {
181 		case -EPROTONOSUPPORT:
182 			status = -EINVAL;
183 			break;
184 		case -ECONNREFUSED:
185 		case -ETIMEDOUT:
186 		case -ENOTCONN:
187 			status = -EAGAIN;
188 			break;
189 		case -ERESTARTSYS:
190 			if (signalled ())
191 				status = -EINTR;
192 			break;
193 		default:
194 			break;
195 		}
196 	}
197 	rpc_release_client(clnt);
198 	return status;
199 }
200 
201 static void gssp_free_receive_pages(struct gssx_arg_accept_sec_context *arg)
202 {
203 	int i;
204 
205 	for (i = 0; i < arg->npages && arg->pages[i]; i++)
206 		__free_page(arg->pages[i]);
207 
208 	kfree(arg->pages);
209 }
210 
211 static int gssp_alloc_receive_pages(struct gssx_arg_accept_sec_context *arg)
212 {
213 	arg->npages = DIV_ROUND_UP(NGROUPS_MAX * 4, PAGE_SIZE);
214 	arg->pages = kcalloc(arg->npages, sizeof(struct page *), GFP_KERNEL);
215 	/*
216 	 * XXX: actual pages are allocated by xdr layer in
217 	 * xdr_partial_copy_from_skb.
218 	 */
219 	if (!arg->pages)
220 		return -ENOMEM;
221 	return 0;
222 }
223 
224 static char *gssp_stringify(struct xdr_netobj *netobj)
225 {
226 	return kstrndup(netobj->data, netobj->len, GFP_KERNEL);
227 }
228 
229 static void gssp_hostbased_service(char **principal)
230 {
231 	char *c;
232 
233 	if (!*principal)
234 		return;
235 
236 	/* terminate and remove realm part */
237 	c = strchr(*principal, '@');
238 	if (c) {
239 		*c = '\0';
240 
241 		/* change service-hostname delimiter */
242 		c = strchr(*principal, '/');
243 		if (c)
244 			*c = '@';
245 	}
246 	if (!c) {
247 		/* not a service principal */
248 		kfree(*principal);
249 		*principal = NULL;
250 	}
251 }
252 
253 /*
254  * Public functions
255  */
256 
257 /* numbers somewhat arbitrary but large enough for current needs */
258 #define GSSX_MAX_OUT_HANDLE	128
259 #define GSSX_MAX_SRC_PRINC	256
260 #define GSSX_KMEMBUF (GSSX_max_output_handle_sz + \
261 			GSSX_max_oid_sz + \
262 			GSSX_max_princ_sz + \
263 			sizeof(struct svc_cred))
264 
265 int gssp_accept_sec_context_upcall(struct net *net,
266 				struct gssp_upcall_data *data)
267 {
268 	struct gssx_ctx ctxh = {
269 		.state = data->in_handle
270 	};
271 	struct gssx_arg_accept_sec_context arg = {
272 		.input_token = data->in_token,
273 	};
274 	struct gssx_ctx rctxh = {
275 		/*
276 		 * pass in the max length we expect for each of these
277 		 * buffers but let the xdr code kmalloc them:
278 		 */
279 		.exported_context_token.len = GSSX_max_output_handle_sz,
280 		.mech.len = GSS_OID_MAX_LEN,
281 		.targ_name.display_name.len = GSSX_max_princ_sz,
282 		.src_name.display_name.len = GSSX_max_princ_sz
283 	};
284 	struct gssx_res_accept_sec_context res = {
285 		.context_handle = &rctxh,
286 		.output_token = &data->out_token
287 	};
288 	struct rpc_message msg = {
289 		.rpc_proc = &gssp_procedures[GSSX_ACCEPT_SEC_CONTEXT],
290 		.rpc_argp = &arg,
291 		.rpc_resp = &res,
292 		.rpc_cred = NULL, /* FIXME ? */
293 	};
294 	struct xdr_netobj client_name = { 0 , NULL };
295 	struct xdr_netobj target_name = { 0, NULL };
296 	int ret;
297 
298 	if (data->in_handle.len != 0)
299 		arg.context_handle = &ctxh;
300 	res.output_token->len = GSSX_max_output_token_sz;
301 
302 	ret = gssp_alloc_receive_pages(&arg);
303 	if (ret)
304 		return ret;
305 
306 	ret = gssp_call(net, &msg);
307 
308 	gssp_free_receive_pages(&arg);
309 
310 	/* we need to fetch all data even in case of error so
311 	 * that we can free special strctures is they have been allocated */
312 	data->major_status = res.status.major_status;
313 	data->minor_status = res.status.minor_status;
314 	if (res.context_handle) {
315 		data->out_handle = rctxh.exported_context_token;
316 		data->mech_oid.len = rctxh.mech.len;
317 		if (rctxh.mech.data) {
318 			memcpy(data->mech_oid.data, rctxh.mech.data,
319 						data->mech_oid.len);
320 			kfree(rctxh.mech.data);
321 		}
322 		client_name = rctxh.src_name.display_name;
323 		target_name = rctxh.targ_name.display_name;
324 	}
325 
326 	if (res.options.count == 1) {
327 		gssx_buffer *value = &res.options.data[0].value;
328 		/* Currently we only decode CREDS_VALUE, if we add
329 		 * anything else we'll have to loop and match on the
330 		 * option name */
331 		if (value->len == 1) {
332 			/* steal group info from struct svc_cred */
333 			data->creds = *(struct svc_cred *)value->data;
334 			data->found_creds = 1;
335 		}
336 		/* whether we use it or not, free data */
337 		kfree(value->data);
338 	}
339 
340 	if (res.options.count != 0) {
341 		kfree(res.options.data);
342 	}
343 
344 	/* convert to GSS_NT_HOSTBASED_SERVICE form and set into creds */
345 	if (data->found_creds) {
346 		if (client_name.data) {
347 			data->creds.cr_raw_principal =
348 					gssp_stringify(&client_name);
349 			data->creds.cr_principal =
350 					gssp_stringify(&client_name);
351 			gssp_hostbased_service(&data->creds.cr_principal);
352 		}
353 		if (target_name.data) {
354 			data->creds.cr_targ_princ =
355 					gssp_stringify(&target_name);
356 			gssp_hostbased_service(&data->creds.cr_targ_princ);
357 		}
358 	}
359 	kfree(client_name.data);
360 	kfree(target_name.data);
361 
362 	return ret;
363 }
364 
365 void gssp_free_upcall_data(struct gssp_upcall_data *data)
366 {
367 	kfree(data->in_handle.data);
368 	kfree(data->out_handle.data);
369 	kfree(data->out_token.data);
370 	free_svc_cred(&data->creds);
371 }
372 
373 /*
374  * Initialization stuff
375  */
376 static unsigned int gssp_version1_counts[ARRAY_SIZE(gssp_procedures)];
377 static const struct rpc_version gssp_version1 = {
378 	.number		= GSSPROXY_VERS_1,
379 	.nrprocs	= ARRAY_SIZE(gssp_procedures),
380 	.procs		= gssp_procedures,
381 	.counts		= gssp_version1_counts,
382 };
383 
384 static const struct rpc_version *gssp_version[] = {
385 	NULL,
386 	&gssp_version1,
387 };
388 
389 static struct rpc_stat gssp_stats;
390 
391 static const struct rpc_program gssp_program = {
392 	.name		= "gssproxy",
393 	.number		= GSSPROXY_PROGRAM,
394 	.nrvers		= ARRAY_SIZE(gssp_version),
395 	.version	= gssp_version,
396 	.stats		= &gssp_stats,
397 };
398