1 /*
2  *  linux/net/sunrpc/gss_rpc_upcall.c
3  *
4  *  Copyright (C) 2012 Simo Sorce <simo@redhat.com>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  */
20 
21 #include <linux/types.h>
22 #include <linux/un.h>
23 
24 #include <linux/sunrpc/svcauth.h>
25 #include "gss_rpc_upcall.h"
26 
27 #define GSSPROXY_SOCK_PATHNAME	"/var/run/gssproxy.sock"
28 
29 #define GSSPROXY_PROGRAM	(400112u)
30 #define GSSPROXY_VERS_1		(1u)
31 
32 /*
33  * Encoding/Decoding functions
34  */
35 
36 enum {
37 	GSSX_NULL = 0,	/* Unused */
38         GSSX_INDICATE_MECHS = 1,
39         GSSX_GET_CALL_CONTEXT = 2,
40         GSSX_IMPORT_AND_CANON_NAME = 3,
41         GSSX_EXPORT_CRED = 4,
42         GSSX_IMPORT_CRED = 5,
43         GSSX_ACQUIRE_CRED = 6,
44         GSSX_STORE_CRED = 7,
45         GSSX_INIT_SEC_CONTEXT = 8,
46         GSSX_ACCEPT_SEC_CONTEXT = 9,
47         GSSX_RELEASE_HANDLE = 10,
48         GSSX_GET_MIC = 11,
49         GSSX_VERIFY = 12,
50         GSSX_WRAP = 13,
51         GSSX_UNWRAP = 14,
52         GSSX_WRAP_SIZE_LIMIT = 15,
53 };
54 
55 #define PROC(proc, name)				\
56 [GSSX_##proc] = {					\
57 	.p_proc   = GSSX_##proc,			\
58 	.p_encode = (kxdreproc_t)gssx_enc_##name,	\
59 	.p_decode = (kxdrdproc_t)gssx_dec_##name,	\
60 	.p_arglen = GSSX_ARG_##name##_sz,		\
61 	.p_replen = GSSX_RES_##name##_sz, 		\
62 	.p_statidx = GSSX_##proc,			\
63 	.p_name   = #proc,				\
64 }
65 
66 static struct rpc_procinfo gssp_procedures[] = {
67 	PROC(INDICATE_MECHS, indicate_mechs),
68         PROC(GET_CALL_CONTEXT, get_call_context),
69         PROC(IMPORT_AND_CANON_NAME, import_and_canon_name),
70         PROC(EXPORT_CRED, export_cred),
71         PROC(IMPORT_CRED, import_cred),
72         PROC(ACQUIRE_CRED, acquire_cred),
73         PROC(STORE_CRED, store_cred),
74         PROC(INIT_SEC_CONTEXT, init_sec_context),
75         PROC(ACCEPT_SEC_CONTEXT, accept_sec_context),
76         PROC(RELEASE_HANDLE, release_handle),
77         PROC(GET_MIC, get_mic),
78         PROC(VERIFY, verify),
79         PROC(WRAP, wrap),
80         PROC(UNWRAP, unwrap),
81         PROC(WRAP_SIZE_LIMIT, wrap_size_limit),
82 };
83 
84 
85 
86 /*
87  * Common transport functions
88  */
89 
90 static const struct rpc_program gssp_program;
91 
92 static int gssp_rpc_create(struct net *net, struct rpc_clnt **_clnt)
93 {
94 	static const struct sockaddr_un gssp_localaddr = {
95 		.sun_family		= AF_LOCAL,
96 		.sun_path		= GSSPROXY_SOCK_PATHNAME,
97 	};
98 	struct rpc_create_args args = {
99 		.net		= net,
100 		.protocol	= XPRT_TRANSPORT_LOCAL,
101 		.address	= (struct sockaddr *)&gssp_localaddr,
102 		.addrsize	= sizeof(gssp_localaddr),
103 		.servername	= "localhost",
104 		.program	= &gssp_program,
105 		.version	= GSSPROXY_VERS_1,
106 		.authflavor	= RPC_AUTH_NULL,
107 		/*
108 		 * Note we want connection to be done in the caller's
109 		 * filesystem namespace.  We therefore turn off the idle
110 		 * timeout, which would result in reconnections being
111 		 * done without the correct namespace:
112 		 */
113 		.flags		= RPC_CLNT_CREATE_NOPING |
114 				  RPC_CLNT_CREATE_NO_IDLE_TIMEOUT
115 	};
116 	struct rpc_clnt *clnt;
117 	int result = 0;
118 
119 	clnt = rpc_create(&args);
120 	if (IS_ERR(clnt)) {
121 		dprintk("RPC:       failed to create AF_LOCAL gssproxy "
122 				"client (errno %ld).\n", PTR_ERR(clnt));
123 		result = PTR_ERR(clnt);
124 		*_clnt = NULL;
125 		goto out;
126 	}
127 
128 	dprintk("RPC:       created new gssp local client (gssp_local_clnt: "
129 			"%p)\n", clnt);
130 	*_clnt = clnt;
131 
132 out:
133 	return result;
134 }
135 
136 void init_gssp_clnt(struct sunrpc_net *sn)
137 {
138 	mutex_init(&sn->gssp_lock);
139 	sn->gssp_clnt = NULL;
140 	init_waitqueue_head(&sn->gssp_wq);
141 }
142 
143 int set_gssp_clnt(struct net *net)
144 {
145 	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
146 	struct rpc_clnt *clnt;
147 	int ret;
148 
149 	mutex_lock(&sn->gssp_lock);
150 	ret = gssp_rpc_create(net, &clnt);
151 	if (!ret) {
152 		if (sn->gssp_clnt)
153 			rpc_shutdown_client(sn->gssp_clnt);
154 		sn->gssp_clnt = clnt;
155 	}
156 	mutex_unlock(&sn->gssp_lock);
157 	wake_up(&sn->gssp_wq);
158 	return ret;
159 }
160 
161 void clear_gssp_clnt(struct sunrpc_net *sn)
162 {
163 	mutex_lock(&sn->gssp_lock);
164 	if (sn->gssp_clnt) {
165 		rpc_shutdown_client(sn->gssp_clnt);
166 		sn->gssp_clnt = NULL;
167 	}
168 	mutex_unlock(&sn->gssp_lock);
169 }
170 
171 static struct rpc_clnt *get_gssp_clnt(struct sunrpc_net *sn)
172 {
173 	struct rpc_clnt *clnt;
174 
175 	mutex_lock(&sn->gssp_lock);
176 	clnt = sn->gssp_clnt;
177 	if (clnt)
178 		atomic_inc(&clnt->cl_count);
179 	mutex_unlock(&sn->gssp_lock);
180 	return clnt;
181 }
182 
183 static int gssp_call(struct net *net, struct rpc_message *msg)
184 {
185 	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
186 	struct rpc_clnt *clnt;
187 	int status;
188 
189 	clnt = get_gssp_clnt(sn);
190 	if (!clnt)
191 		return -EIO;
192 	status = rpc_call_sync(clnt, msg, 0);
193 	if (status < 0) {
194 		dprintk("gssp: rpc_call returned error %d\n", -status);
195 		switch (status) {
196 		case -EPROTONOSUPPORT:
197 			status = -EINVAL;
198 			break;
199 		case -ECONNREFUSED:
200 		case -ETIMEDOUT:
201 		case -ENOTCONN:
202 			status = -EAGAIN;
203 			break;
204 		case -ERESTARTSYS:
205 			if (signalled ())
206 				status = -EINTR;
207 			break;
208 		default:
209 			break;
210 		}
211 	}
212 	rpc_release_client(clnt);
213 	return status;
214 }
215 
216 static void gssp_free_receive_pages(struct gssx_arg_accept_sec_context *arg)
217 {
218 	int i;
219 
220 	for (i = 0; i < arg->npages && arg->pages[i]; i++)
221 		__free_page(arg->pages[i]);
222 }
223 
224 static int gssp_alloc_receive_pages(struct gssx_arg_accept_sec_context *arg)
225 {
226 	arg->npages = DIV_ROUND_UP(NGROUPS_MAX * 4, PAGE_SIZE);
227 	arg->pages = kzalloc(arg->npages * sizeof(struct page *), GFP_KERNEL);
228 	/*
229 	 * XXX: actual pages are allocated by xdr layer in
230 	 * xdr_partial_copy_from_skb.
231 	 */
232 	if (!arg->pages)
233 		return -ENOMEM;
234 	return 0;
235 }
236 
237 /*
238  * Public functions
239  */
240 
241 /* numbers somewhat arbitrary but large enough for current needs */
242 #define GSSX_MAX_OUT_HANDLE	128
243 #define GSSX_MAX_SRC_PRINC	256
244 #define GSSX_KMEMBUF (GSSX_max_output_handle_sz + \
245 			GSSX_max_oid_sz + \
246 			GSSX_max_princ_sz + \
247 			sizeof(struct svc_cred))
248 
249 int gssp_accept_sec_context_upcall(struct net *net,
250 				struct gssp_upcall_data *data)
251 {
252 	struct gssx_ctx ctxh = {
253 		.state = data->in_handle
254 	};
255 	struct gssx_arg_accept_sec_context arg = {
256 		.input_token = data->in_token,
257 	};
258 	struct gssx_ctx rctxh = {
259 		/*
260 		 * pass in the max length we expect for each of these
261 		 * buffers but let the xdr code kmalloc them:
262 		 */
263 		.exported_context_token.len = GSSX_max_output_handle_sz,
264 		.mech.len = GSS_OID_MAX_LEN,
265 		.src_name.display_name.len = GSSX_max_princ_sz
266 	};
267 	struct gssx_res_accept_sec_context res = {
268 		.context_handle = &rctxh,
269 		.output_token = &data->out_token
270 	};
271 	struct rpc_message msg = {
272 		.rpc_proc = &gssp_procedures[GSSX_ACCEPT_SEC_CONTEXT],
273 		.rpc_argp = &arg,
274 		.rpc_resp = &res,
275 		.rpc_cred = NULL, /* FIXME ? */
276 	};
277 	struct xdr_netobj client_name = { 0 , NULL };
278 	int ret;
279 
280 	if (data->in_handle.len != 0)
281 		arg.context_handle = &ctxh;
282 	res.output_token->len = GSSX_max_output_token_sz;
283 
284 	ret = gssp_alloc_receive_pages(&arg);
285 	if (ret)
286 		return ret;
287 
288 	/* use nfs/ for targ_name ? */
289 
290 	ret = gssp_call(net, &msg);
291 
292 	gssp_free_receive_pages(&arg);
293 
294 	/* we need to fetch all data even in case of error so
295 	 * that we can free special strctures is they have been allocated */
296 	data->major_status = res.status.major_status;
297 	data->minor_status = res.status.minor_status;
298 	if (res.context_handle) {
299 		data->out_handle = rctxh.exported_context_token;
300 		data->mech_oid.len = rctxh.mech.len;
301 		if (rctxh.mech.data)
302 			memcpy(data->mech_oid.data, rctxh.mech.data,
303 						data->mech_oid.len);
304 		client_name = rctxh.src_name.display_name;
305 	}
306 
307 	if (res.options.count == 1) {
308 		gssx_buffer *value = &res.options.data[0].value;
309 		/* Currently we only decode CREDS_VALUE, if we add
310 		 * anything else we'll have to loop and match on the
311 		 * option name */
312 		if (value->len == 1) {
313 			/* steal group info from struct svc_cred */
314 			data->creds = *(struct svc_cred *)value->data;
315 			data->found_creds = 1;
316 		}
317 		/* whether we use it or not, free data */
318 		kfree(value->data);
319 	}
320 
321 	if (res.options.count != 0) {
322 		kfree(res.options.data);
323 	}
324 
325 	/* convert to GSS_NT_HOSTBASED_SERVICE form and set into creds */
326 	if (data->found_creds && client_name.data != NULL) {
327 		char *c;
328 
329 		data->creds.cr_principal = kstrndup(client_name.data,
330 						client_name.len, GFP_KERNEL);
331 		if (data->creds.cr_principal) {
332 			/* terminate and remove realm part */
333 			c = strchr(data->creds.cr_principal, '@');
334 			if (c) {
335 				*c = '\0';
336 
337 				/* change service-hostname delimiter */
338 				c = strchr(data->creds.cr_principal, '/');
339 				if (c) *c = '@';
340 			}
341 			if (!c) {
342 				/* not a service principal */
343 				kfree(data->creds.cr_principal);
344 				data->creds.cr_principal = NULL;
345 			}
346 		}
347 	}
348 	kfree(client_name.data);
349 
350 	return ret;
351 }
352 
353 void gssp_free_upcall_data(struct gssp_upcall_data *data)
354 {
355 	kfree(data->in_handle.data);
356 	kfree(data->out_handle.data);
357 	kfree(data->out_token.data);
358 	free_svc_cred(&data->creds);
359 }
360 
361 /*
362  * Initialization stuff
363  */
364 
365 static const struct rpc_version gssp_version1 = {
366 	.number		= GSSPROXY_VERS_1,
367 	.nrprocs	= ARRAY_SIZE(gssp_procedures),
368 	.procs		= gssp_procedures,
369 };
370 
371 static const struct rpc_version *gssp_version[] = {
372 	NULL,
373 	&gssp_version1,
374 };
375 
376 static struct rpc_stat gssp_stats;
377 
378 static const struct rpc_program gssp_program = {
379 	.name		= "gssproxy",
380 	.number		= GSSPROXY_PROGRAM,
381 	.nrvers		= ARRAY_SIZE(gssp_version),
382 	.version	= gssp_version,
383 	.stats		= &gssp_stats,
384 };
385