xenstore_dev.c revision 279562 
1/*
2 * xenstore_dev.c
3 *
4 * Driver giving user-space access to the kernel's connection to the
5 * XenStore service.
6 *
7 * Copyright (c) 2005, Christian Limpach
8 * Copyright (c) 2005, Rusty Russell, IBM Corporation
9 *
10 * This file may be distributed separately from the Linux kernel, or
11 * incorporated into other software packages, subject to the following license:
12 *
13 * Permission is hereby granted, free of charge, to any person obtaining a copy
14 * of this source file (the "Software"), to deal in the Software without
15 * restriction, including without limitation the rights to use, copy, modify,
16 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
17 * and to permit persons to whom the Software is furnished to do so, subject to
18 * the following conditions:
19 *
20 * The above copyright notice and this permission notice shall be included in
21 * all copies or substantial portions of the Software.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
24 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
25 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
26 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
27 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
28 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
29 * IN THE SOFTWARE.
30 */
31
32
33#include <sys/cdefs.h>
34__FBSDID("$FreeBSD: stable/10/sys/xen/xenstore/xenstore_dev.c 279562 2015-03-03 10:11:58Z royger $");
35
36#include <sys/types.h>
37#include <sys/cdefs.h>
38#include <sys/errno.h>
39#include <sys/uio.h>
40#include <sys/param.h>
41#include <sys/systm.h>
42#include <sys/proc.h>
43#include <sys/kernel.h>
44#include <sys/malloc.h>
45#include <sys/conf.h>
46
47#include <xen/xen-os.h>
48
49#include <xen/hypervisor.h>
50#include <xen/xenstore/xenstorevar.h>
51#include <xen/xenstore/xenstore_internal.h>
52
53struct xs_dev_transaction {
54	LIST_ENTRY(xs_dev_transaction) list;
55	struct xs_transaction handle;
56};
57
58struct xs_dev_data {
59	/* In-progress transaction. */
60	LIST_HEAD(xdd_list_head, xs_dev_transaction) transactions;
61
62	/* Partial request. */
63	unsigned int len;
64	union {
65		struct xsd_sockmsg msg;
66		char buffer[PAGE_SIZE];
67	} u;
68
69	/* Response queue. */
70#define MASK_READ_IDX(idx) ((idx)&(PAGE_SIZE-1))
71	char read_buffer[PAGE_SIZE];
72	unsigned int read_cons, read_prod;
73};
74
75static int
76xs_dev_read(struct cdev *dev, struct uio *uio, int ioflag)
77{
78	int error;
79	struct xs_dev_data *u;
80
81	error = devfs_get_cdevpriv((void **)&u);
82	if (error != 0)
83		return (error);
84
85	while (u->read_prod == u->read_cons) {
86		error = tsleep(u, PCATCH, "xsdread", hz/10);
87		if (error && error != EWOULDBLOCK)
88			return (error);
89	}
90
91	while (uio->uio_resid > 0) {
92		if (u->read_cons == u->read_prod)
93			break;
94		error = uiomove(&u->read_buffer[MASK_READ_IDX(u->read_cons)],
95		    1, uio);
96		if (error)
97			return (error);
98		u->read_cons++;
99	}
100	return (0);
101}
102
103static void
104xs_queue_reply(struct xs_dev_data *u, char *data, unsigned int len)
105{
106	int i;
107
108	for (i = 0; i < len; i++, u->read_prod++)
109		u->read_buffer[MASK_READ_IDX(u->read_prod)] = data[i];
110
111	KASSERT((u->read_prod - u->read_cons) <= sizeof(u->read_buffer),
112	    ("xenstore reply too big"));
113
114	wakeup(u);
115}
116
117static int
118xs_dev_write(struct cdev *dev, struct uio *uio, int ioflag)
119{
120	int error;
121	struct xs_dev_data *u;
122	struct xs_dev_transaction *trans;
123	void *reply;
124	int len = uio->uio_resid;
125
126	error = devfs_get_cdevpriv((void **)&u);
127	if (error != 0)
128		return (error);
129
130	if ((len + u->len) > sizeof(u->u.buffer))
131		return (EINVAL);
132
133	error = uiomove(u->u.buffer + u->len, len, uio);
134	if (error)
135		return (error);
136
137	u->len += len;
138	if (u->len < (sizeof(u->u.msg) + u->u.msg.len))
139		return (0);
140
141	switch (u->u.msg.type) {
142	case XS_TRANSACTION_START:
143	case XS_TRANSACTION_END:
144	case XS_DIRECTORY:
145	case XS_READ:
146	case XS_GET_PERMS:
147	case XS_RELEASE:
148	case XS_GET_DOMAIN_PATH:
149	case XS_WRITE:
150	case XS_MKDIR:
151	case XS_RM:
152	case XS_SET_PERMS:
153		error = xs_dev_request_and_reply(&u->u.msg, &reply);
154		if (!error) {
155			if (u->u.msg.type == XS_TRANSACTION_START) {
156				trans = malloc(sizeof(*trans), M_XENSTORE,
157				    M_WAITOK);
158				trans->handle.id = strtoul(reply, NULL, 0);
159				LIST_INSERT_HEAD(&u->transactions, trans, list);
160			} else if (u->u.msg.type == XS_TRANSACTION_END) {
161				LIST_FOREACH(trans, &u->transactions, list)
162					if (trans->handle.id == u->u.msg.tx_id)
163						break;
164#if 0 /* XXX does this mean the list is empty? */
165				BUG_ON(&trans->list == &u->transactions);
166#endif
167				LIST_REMOVE(trans, list);
168				free(trans, M_XENSTORE);
169			}
170			xs_queue_reply(u, (char *)&u->u.msg, sizeof(u->u.msg));
171			xs_queue_reply(u, (char *)reply, u->u.msg.len);
172			free(reply, M_XENSTORE);
173		}
174		break;
175
176	default:
177		error = EINVAL;
178		break;
179	}
180
181	if (error == 0)
182		u->len = 0;
183
184	return (error);
185}
186
187static void
188xs_dev_dtor(void *arg)
189{
190	struct xs_dev_data *u = arg;
191	struct xs_dev_transaction *trans, *tmp;
192
193	LIST_FOREACH_SAFE(trans, &u->transactions, list, tmp) {
194		xs_transaction_end(trans->handle, 1);
195		LIST_REMOVE(trans, list);
196		free(trans, M_XENSTORE);
197	}
198
199	free(u, M_XENSTORE);
200}
201
202static int
203xs_dev_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
204{
205	struct xs_dev_data *u;
206	int error;
207
208	u = malloc(sizeof(*u), M_XENSTORE, M_WAITOK|M_ZERO);
209	LIST_INIT(&u->transactions);
210	error = devfs_set_cdevpriv(u, xs_dev_dtor);
211	if (error != 0)
212		free(u, M_XENSTORE);
213
214	return (error);
215}
216
217static struct cdevsw xs_dev_cdevsw = {
218	.d_version = D_VERSION,
219	.d_read = xs_dev_read,
220	.d_write = xs_dev_write,
221	.d_open = xs_dev_open,
222	.d_name = "xs_dev",
223};
224
225void
226xs_dev_init()
227{
228
229	make_dev_credf(MAKEDEV_ETERNAL, &xs_dev_cdevsw, 0, NULL,
230	    UID_ROOT, GID_WHEEL, 0400, "xen/xenstore");
231}
232