xref: /third_party/FreeBSD/sys/dev/usb/usb_parse.c (revision f9f848fa) 
1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2008-2020 Hans Petter Selasky. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#include "implementation/global_implementation.h"
29
30/*------------------------------------------------------------------------*
31 *	usb_desc_foreach
32 *
33 * This function is the safe way to iterate across the USB config
34 * descriptor. It contains several checks against invalid
35 * descriptors. If the "desc" argument passed to this function is
36 * "NULL" the first descriptor, if any, will be returned.
37 *
38 * Return values:
39 *   NULL: End of descriptors
40 *   Else: Next descriptor after "desc"
41 *------------------------------------------------------------------------*/
42struct usb_descriptor *
43usb_desc_foreach(struct usb_config_descriptor *cd,
44    struct usb_descriptor *_desc)
45{
46	uint8_t *desc_next;
47	uint8_t *start;
48	uint8_t *end;
49	uint8_t *desc;
50
51	/* be NULL safe */
52	if (cd == NULL)
53		return (NULL);
54
55	/* We assume that the "wTotalLength" has been checked. */
56	start = (uint8_t *)cd;
57	end = start + UGETW(cd->wTotalLength);
58	desc = (uint8_t *)_desc;
59
60	/* Get start of next USB descriptor. */
61	if (desc == NULL)
62		desc = start;
63	else
64		desc = desc + desc[0];
65
66	/* Check that the next USB descriptor is within the range. */
67	if ((desc < start) || (desc >= end))
68		return (NULL);		/* out of range, or EOD */
69
70	/* Check that the second next USB descriptor is within range. */
71	desc_next = desc + desc[0];
72	if ((desc_next < start) || (desc_next > end))
73		return (NULL);		/* out of range */
74
75	/* Check minimum descriptor length. */
76	if (desc[0] < 3)
77		return (NULL);		/* too short descriptor */
78
79	/* Return start of next descriptor. */
80	return ((struct usb_descriptor *)desc);
81}
82
83/*------------------------------------------------------------------------*
84 *	usb_idesc_foreach
85 *
86 * This function will iterate the interface descriptors in the config
87 * descriptor. The parse state structure should be zeroed before
88 * calling this function the first time.
89 *
90 * Return values:
91 *   NULL: End of descriptors
92 *   Else: A valid interface descriptor
93 *------------------------------------------------------------------------*/
94struct usb_interface_descriptor *
95usb_idesc_foreach(struct usb_config_descriptor *cd,
96    struct usb_idesc_parse_state *ps)
97{
98	struct usb_interface_descriptor *id;
99	uint8_t new_iface;
100
101	/* retrieve current descriptor */
102	id = (struct usb_interface_descriptor *)ps->desc;
103	/* default is to start a new interface */
104	new_iface = 1;
105
106	while (1) {
107		id = (struct usb_interface_descriptor *)
108		    usb_desc_foreach(cd, (struct usb_descriptor *)id);
109		if (id == NULL)
110			break;
111		if ((id->bDescriptorType == UDESC_INTERFACE) &&
112		    (id->bLength >= sizeof(*id))) {
113			if (ps->iface_no_last == id->bInterfaceNumber) {
114				/*
115				 * Don't allow more than 256 alternate
116				 * settings to avoid overflowing the
117				 * alternate index which is a 8-bit
118				 * variable.
119				 */
120				if (ps->iface_index_alt == 255) {
121					DPRINTF("Interface(%u) has more than 256 alternate settings\n",
122					    id->bInterfaceNumber);
123					continue;
124				}
125				new_iface = 0;
126			}
127			ps->iface_no_last = id->bInterfaceNumber;
128			break;
129		}
130	}
131
132	if (ps->desc == NULL) {
133		/* first time or zero descriptors */
134	} else if (new_iface) {
135		/* new interface */
136		ps->iface_index ++;
137		ps->iface_index_alt = 0;
138	} else {
139		/* new alternate interface */
140		ps->iface_index_alt ++;
141	}
142#if (USB_IFACE_MAX <= 0)
143#error "USB_IFACE_MAX must be defined greater than zero"
144#endif
145	/* check for too many interfaces */
146	if (ps->iface_index >= USB_IFACE_MAX) {
147		DPRINTF("Interface limit reached\n");
148		id = NULL;
149	}
150
151	/* store and return current descriptor */
152	ps->desc = (struct usb_descriptor *)id;
153	return (id);
154}
155
156/*------------------------------------------------------------------------*
157 *	usb_edesc_foreach
158 *
159 * This function will iterate all the endpoint descriptors within an
160 * interface descriptor. Starting value for the "ped" argument should
161 * be a valid interface descriptor.
162 *
163 * Return values:
164 *   NULL: End of descriptors
165 *   Else: A valid endpoint descriptor
166 *------------------------------------------------------------------------*/
167struct usb_endpoint_descriptor *
168usb_edesc_foreach(struct usb_config_descriptor *cd,
169    struct usb_endpoint_descriptor *ped)
170{
171	struct usb_descriptor *desc;
172
173	desc = ((struct usb_descriptor *)ped);
174
175	while ((desc = usb_desc_foreach(cd, desc))) {
176		if (desc->bDescriptorType == UDESC_INTERFACE) {
177			break;
178		}
179		if (desc->bDescriptorType == UDESC_ENDPOINT) {
180			if (desc->bLength < sizeof(*ped)) {
181				/* endpoint descriptor is invalid */
182				break;
183			}
184			return ((struct usb_endpoint_descriptor *)desc);
185		}
186	}
187	return (NULL);
188}
189
190/*------------------------------------------------------------------------*
191 *	usb_ed_comp_foreach
192 *
193 * This function will iterate all the endpoint companion descriptors
194 * within an endpoint descriptor in an interface descriptor. Starting
195 * value for the "ped" argument should be a valid endpoint companion
196 * descriptor.
197 *
198 * Return values:
199 *   NULL: End of descriptors
200 *   Else: A valid endpoint companion descriptor
201 *------------------------------------------------------------------------*/
202struct usb_endpoint_ss_comp_descriptor *
203usb_ed_comp_foreach(struct usb_config_descriptor *cd,
204    struct usb_endpoint_ss_comp_descriptor *ped)
205{
206	struct usb_descriptor *desc;
207
208	desc = ((struct usb_descriptor *)ped);
209
210	while ((desc = usb_desc_foreach(cd, desc))) {
211		if (desc->bDescriptorType == UDESC_INTERFACE)
212			break;
213		if (desc->bDescriptorType == UDESC_ENDPOINT)
214			break;
215		if (desc->bDescriptorType == UDESC_ENDPOINT_SS_COMP) {
216			if (desc->bLength < sizeof(*ped)) {
217				/* endpoint companion descriptor is invalid */
218				break;
219			}
220			return ((struct usb_endpoint_ss_comp_descriptor *)desc);
221		}
222	}
223	return (NULL);
224}
225
226/*------------------------------------------------------------------------*
227 *	usbd_get_no_descriptors
228 *
229 * This function will count the total number of descriptors in the
230 * configuration descriptor of type "type".
231 *------------------------------------------------------------------------*/
232uint8_t
233usbd_get_no_descriptors(struct usb_config_descriptor *cd, uint8_t type)
234{
235	struct usb_descriptor *desc = NULL;
236	uint8_t count = 0;
237
238	while ((desc = usb_desc_foreach(cd, desc))) {
239		if (desc->bDescriptorType == type) {
240			count++;
241			if (count == 0xFF)
242				break;			/* crazy */
243		}
244	}
245	return (count);
246}
247
248/*------------------------------------------------------------------------*
249 *	usbd_get_no_alts
250 *
251 * Return value:
252 *   Number of alternate settings for the given interface descriptor
253 *   pointer. If the USB descriptor is corrupt, the returned value can
254 *   be greater than the actual number of alternate settings.
255 *------------------------------------------------------------------------*/
256uint8_t
257usbd_get_no_alts(struct usb_config_descriptor *cd,
258    struct usb_interface_descriptor *id)
259{
260	struct usb_descriptor *desc;
261	uint8_t n;
262	uint8_t ifaceno;
263
264	/* Reset interface count */
265
266	n = 0;
267
268	/* Get the interface number */
269
270	ifaceno = id->bInterfaceNumber;
271
272	/* Iterate all the USB descriptors */
273
274	desc = NULL;
275	while ((desc = usb_desc_foreach(cd, desc))) {
276		if ((desc->bDescriptorType == UDESC_INTERFACE) &&
277		    (desc->bLength >= sizeof(*id))) {
278			id = (struct usb_interface_descriptor *)desc;
279			if (id->bInterfaceNumber == ifaceno) {
280				n++;
281				if (n == 0xFF)
282					break;		/* crazy */
283			}
284		}
285	}
286	return (n);
287}
288