[thirdparty/systemd.git] / udev / lib / libudev-monitor.c

/*
 * libudev - interface to udev device information
 *
 * Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "config.h"

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <dirent.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>

#include "libudev.h"
#include "libudev-private.h"
#include "../udev.h"

struct udev_monitor {
	struct udev *udev;
	int refcount;
	int socket;
};

/**
 * udev_monitor_new_from_socket:
 * @udev: udev library context
 * @socket_path: unix socket path
 *
 * Create new udev monitor, setup and connect to a specified socket. The
 * path to a socket can point to an existing socket file, or it will be
 * created if needed. If neccessary, the permissions adjustment as well as
 * the later cleanup of the socket file, needs to be done by the caller.
 * If the socket path starts with a '@' character, an abstract namespace
 * socket will be used.
 *
 * The initial refcount is 1, and needs to be decremented to
 * release the ressources of the udev monitor.
 *
 * Returns: a new udev monitor, or #NULL, in case of an error
 **/
struct udev_monitor *udev_monitor_new_from_socket(struct udev *udev, const char *socket_path)
{
	struct udev_monitor *udev_monitor;
	struct sockaddr_un saddr;
	socklen_t addrlen;
	const int on = 1;

	if (udev == NULL)
		return NULL;
	if (socket_path == NULL)
		return NULL;
	udev_monitor = malloc(sizeof(struct udev_monitor));
	if (udev_monitor == NULL)
		return NULL;
	memset(udev_monitor, 0x00, sizeof(struct udev_monitor));
	udev_monitor->refcount = 1;
	udev_monitor->udev = udev;

	memset(&saddr, 0x00, sizeof(saddr));
	saddr.sun_family = AF_LOCAL;
	strcpy(saddr.sun_path, socket_path);
	addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path);

	/* translate leading '@' to abstract namespace */
	if (saddr.sun_path[0] == '@')
		saddr.sun_path[0] = '\0';

	udev_monitor->socket = socket(AF_LOCAL, SOCK_DGRAM, 0);
	if (udev_monitor->socket == -1) {
		log_err(udev, "error getting socket: %s\n", strerror(errno));
		free(udev_monitor);
		return NULL;
	}

	if (bind(udev_monitor->socket, (struct sockaddr *) &saddr, addrlen) < 0) {
		log_err(udev, "bind failed: %s\n", strerror(errno));
		close(udev_monitor->socket);
		free(udev_monitor);
		return NULL;
	}

	/* enable receiving of the sender credentials */
	setsockopt(udev_monitor->socket, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
	log_info(udev_monitor->udev, "udev_monitor: %p created\n", udev_monitor);

	return udev_monitor;
}

/**
 * udev_monitor_ref:
 * @udev_monitor: udev monitor
 *
 * Take a reference of a udev monitor.
 *
 * Returns: the passed udev monitor
 **/
struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
{
	if (udev_monitor == NULL)
		return NULL;
	udev_monitor->refcount++;
	return udev_monitor;
}

/**
 * udev_monitor_unref:
 * @udev_monitor: udev monitor
 *
 * Drop a reference of a udev monitor. If the refcount reaches zero,
 * the bound socket will be closed, and the ressources of the monitor
 * will be released.
 *
 **/
void udev_monitor_unref(struct udev_monitor *udev_monitor)
{
	if (udev_monitor == NULL)
		return;
	udev_monitor->refcount--;
	if (udev_monitor->refcount > 0)
		return;
	close(udev_monitor->socket);
	log_info(udev_monitor->udev, "udev_monitor: %p released\n", udev_monitor);
	free(udev_monitor);
}

/**
 * udev_monitor_get_udev:
 * @udev_monitor: udev monitor
 *
 * Retrieve the udev library context the device was created with.
 *
 * Returns: the udev library context
 **/
struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor)
{
	if (udev_monitor == NULL)
		return NULL;
	return udev_monitor->udev;
}

/**
 * udev_monitor_get_fd:
 * @udev_monitor: udev monitor
 *
 * Retrieve the socket file descriptor associated with the monitor.
 *
 * Returns: the socket file descriptor
 **/
int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
{
	if (udev_monitor == NULL)
		return -1;
	return udev_monitor->socket;
}

/**
 * udev_monitor_get_device:
 * @udev_monitor: udev monitor
 *
 * Retrieve data from the udev monitor socket, allocate a new udev
 * device, and fill in the received data, and return the device.
 *
 * Only socket connections with uid=0 are accepted. The caller
 * need to make sure, that there is data to read from the socket,
 * the call will block until the socket becomes readable.
 *
 * The initial refcount is 1, and needs to be decremented to
 * release the ressources of the udev device.
 *
 * Returns: a new udev device, or #NULL, in case of an error
 **/
struct udev_device *udev_monitor_get_device(struct udev_monitor *udev_monitor)
{
	struct udev_device *udev_device;
	struct msghdr smsg;
	struct cmsghdr *cmsg;
	struct iovec iov;
	struct ucred *cred;
	char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
	char buf[4096];
	size_t bufpos;

	if (udev_monitor == NULL)
		return NULL;
	memset(buf, 0x00, sizeof(buf));
	iov.iov_base = &buf;
	iov.iov_len = sizeof(buf);
	memset (&smsg, 0x00, sizeof(struct msghdr));
	smsg.msg_iov = &iov;
	smsg.msg_iovlen = 1;
	smsg.msg_control = cred_msg;
	smsg.msg_controllen = sizeof(cred_msg);

	if (recvmsg(udev_monitor->socket, &smsg, 0) < 0) {
		if (errno != EINTR)
			log_info(udev_monitor->udev, "unable to receive message");
		return NULL;
	}
	cmsg = CMSG_FIRSTHDR(&smsg);
	cred = (struct ucred *)CMSG_DATA (cmsg);

	if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
		log_info(udev_monitor->udev, "no sender credentials received, message ignored");
		return NULL;
	}

	if (cred->uid != 0) {
		log_info(udev_monitor->udev, "sender uid=%d, message ignored", cred->uid);
		return NULL;
	}

	/* skip header */
	bufpos = strlen(buf) + 1;
	if (bufpos < sizeof("a@/d") || bufpos >= sizeof(buf)) {
		log_info(udev_monitor->udev, "invalid message length");
		return NULL;
	}

	/* check message header */
	if (strstr(buf, "@/") == NULL) {
		log_info(udev_monitor->udev, "unrecognized message header");
		return NULL;
	}

	udev_device = device_init(udev_monitor->udev);
	if (udev_device == NULL) {
		return NULL;
	}

	while (bufpos < sizeof(buf)) {
		char *key;
		size_t keylen;

		key = &buf[bufpos];
		keylen = strlen(key);
		if (keylen == 0)
			break;
		bufpos += keylen + 1;

		if (strncmp(key, "DEVPATH=", 8) == 0) {
			udev_device->devpath = strdup(&key[8]);
		} else if (strncmp(key, "SUBSYSTEM=", 10) == 0) {
			udev_device->subsystem = strdup(&key[10]);
		} else if (strncmp(key, "DEVNAME=", 8) == 0) {
			udev_device->devname = strdup(&key[8]);
		} else if (strncmp(key, "DEVLINKS=", 9) == 0) {
			char *slink = &key[9];
			char *next = strchr(slink, ' ');

			while (next != NULL) {
				next[0] = '\0';
				name_list_add(&udev_device->link_list, slink, 0);
				slink = &next[1];
				next = strchr(slink, ' ');
			}
			if (slink[0] != '\0')
				name_list_add(&udev_device->link_list, slink, 0);
		}
		name_list_add(&udev_device->env_list, key, 0);
	}

	return udev_device;
}
Commit	Line	Data
ba6929f6 KS	1	/*
	2	* libudev - interface to udev device information
	3	*
	4	* Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
	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, see <http://www.gnu.org/licenses/>.
	18	*/
	19
	20	#include "config.h"
	21
	22	#include <stdio.h>
	23	#include <stdlib.h>
	24	#include <stddef.h>
	25	#include <unistd.h>
	26	#include <errno.h>
	27	#include <string.h>
	28	#include <dirent.h>
	29	#include <sys/stat.h>
	30	#include <sys/socket.h>
	31	#include <sys/un.h>
	32
	33	#include "libudev.h"
	34	#include "libudev-private.h"
	35	#include "../udev.h"
	36
	37	struct udev_monitor {
	38	struct udev *udev;
	39	int refcount;
	40	int socket;
	41	};
	42
7d8787b3 KS	43	/**
	44	* udev_monitor_new_from_socket:
	45	* @udev: udev library context
	46	* @socket_path: unix socket path
	47	*
	48	* Create new udev monitor, setup and connect to a specified socket. The
	49	* path to a socket can point to an existing socket file, or it will be
	50	* created if needed. If neccessary, the permissions adjustment as well as
	51	* the later cleanup of the socket file, needs to be done by the caller.
	52	* If the socket path starts with a '@' character, an abstract namespace
	53	* socket will be used.
	54	*
	55	* The initial refcount is 1, and needs to be decremented to
	56	* release the ressources of the udev monitor.
	57	*
	58	* Returns: a new udev monitor, or #NULL, in case of an error
	59	**/
ba6929f6 KS	60	struct udev_monitor udev_monitor_new_from_socket(struct udev udev, const char *socket_path)
	61	{
	62	struct udev_monitor *udev_monitor;
	63	struct sockaddr_un saddr;
	64	socklen_t addrlen;
	65	const int on = 1;
	66
	67	if (udev == NULL)
	68	return NULL;
	69	if (socket_path == NULL)
	70	return NULL;
	71	udev_monitor = malloc(sizeof(struct udev_monitor));
	72	if (udev_monitor == NULL)
	73	return NULL;
	74	memset(udev_monitor, 0x00, sizeof(struct udev_monitor));
	75	udev_monitor->refcount = 1;
	76	udev_monitor->udev = udev;
	77
	78	memset(&saddr, 0x00, sizeof(saddr));
	79	saddr.sun_family = AF_LOCAL;
	80	strcpy(saddr.sun_path, socket_path);
	81	addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path);
	82
	83	/* translate leading '@' to abstract namespace */
	84	if (saddr.sun_path[0] == '@')
	85	saddr.sun_path[0] = '\0';
	86
	87	udev_monitor->socket = socket(AF_LOCAL, SOCK_DGRAM, 0);
	88	if (udev_monitor->socket == -1) {
	89	log_err(udev, "error getting socket: %s\n", strerror(errno));
	90	free(udev_monitor);
	91	return NULL;
	92	}
	93
	94	if (bind(udev_monitor->socket, (struct sockaddr *) &saddr, addrlen) < 0) {
	95	log_err(udev, "bind failed: %s\n", strerror(errno));
	96	close(udev_monitor->socket);
	97	free(udev_monitor);
	98	return NULL;
	99	}
	100
	101	/* enable receiving of the sender credentials */
	102	setsockopt(udev_monitor->socket, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
	103	log_info(udev_monitor->udev, "udev_monitor: %p created\n", udev_monitor);
	104
	105	return udev_monitor;
	106	}
	107
7d8787b3 KS	108	/**
	109	* udev_monitor_ref:
	110	* @udev_monitor: udev monitor
	111	*
	112	* Take a reference of a udev monitor.
	113	*
	114	* Returns: the passed udev monitor
	115	**/
ba6929f6 KS	116	struct udev_monitor udev_monitor_ref(struct udev_monitor udev_monitor)
	117	{
	118	if (udev_monitor == NULL)
	119	return NULL;
	120	udev_monitor->refcount++;
	121	return udev_monitor;
	122	}
	123
7d8787b3 KS	124	/**
	125	* udev_monitor_unref:
	126	* @udev_monitor: udev monitor
	127	*
	128	* Drop a reference of a udev monitor. If the refcount reaches zero,
	129	* the bound socket will be closed, and the ressources of the monitor
	130	* will be released.
	131	*
	132	**/
ba6929f6 KS	133	void udev_monitor_unref(struct udev_monitor *udev_monitor)
	134	{
	135	if (udev_monitor == NULL)
	136	return;
	137	udev_monitor->refcount--;
	138	if (udev_monitor->refcount > 0)
	139	return;
	140	close(udev_monitor->socket);
	141	log_info(udev_monitor->udev, "udev_monitor: %p released\n", udev_monitor);
	142	free(udev_monitor);
	143	}
	144
7d8787b3 KS	145	/**
	146	* udev_monitor_get_udev:
	147	* @udev_monitor: udev monitor
	148	*
	149	* Retrieve the udev library context the device was created with.
	150	*
	151	* Returns: the udev library context
	152	**/
ba6929f6 KS	153	struct udev udev_monitor_get_udev(struct udev_monitor udev_monitor)
	154	{
	155	if (udev_monitor == NULL)
	156	return NULL;
	157	return udev_monitor->udev;
	158	}
	159
7d8787b3 KS	160	/**
	161	* udev_monitor_get_fd:
	162	* @udev_monitor: udev monitor
	163	*
	164	* Retrieve the socket file descriptor associated with the monitor.
	165	*
	166	* Returns: the socket file descriptor
	167	**/
ba6929f6 KS	168	int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
	169	{
	170	if (udev_monitor == NULL)
	171	return -1;
	172	return udev_monitor->socket;
	173	}
	174
7d8787b3 KS	175	/**
	176	* udev_monitor_get_device:
	177	* @udev_monitor: udev monitor
	178	*
	179	* Retrieve data from the udev monitor socket, allocate a new udev
	180	* device, and fill in the received data, and return the device.
	181	*
	182	* Only socket connections with uid=0 are accepted. The caller
	183	* need to make sure, that there is data to read from the socket,
	184	* the call will block until the socket becomes readable.
	185	*
	186	* The initial refcount is 1, and needs to be decremented to
	187	* release the ressources of the udev device.
	188	*
	189	* Returns: a new udev device, or #NULL, in case of an error
	190	**/
ba6929f6 KS	191	struct udev_device udev_monitor_get_device(struct udev_monitor udev_monitor)
	192	{
	193	struct udev_device *udev_device;
	194	struct msghdr smsg;
	195	struct cmsghdr *cmsg;
	196	struct iovec iov;
	197	struct ucred *cred;
	198	char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
	199	char buf[4096];
	200	size_t bufpos;
	201
	202	if (udev_monitor == NULL)
	203	return NULL;
	204	memset(buf, 0x00, sizeof(buf));
	205	iov.iov_base = &buf;
	206	iov.iov_len = sizeof(buf);
	207	memset (&smsg, 0x00, sizeof(struct msghdr));
	208	smsg.msg_iov = &iov;
	209	smsg.msg_iovlen = 1;
	210	smsg.msg_control = cred_msg;
	211	smsg.msg_controllen = sizeof(cred_msg);
	212
	213	if (recvmsg(udev_monitor->socket, &smsg, 0) < 0) {
	214	if (errno != EINTR)
	215	log_info(udev_monitor->udev, "unable to receive message");
	216	return NULL;
	217	}
	218	cmsg = CMSG_FIRSTHDR(&smsg);
	219	cred = (struct ucred *)CMSG_DATA (cmsg);
	220
	221	if (cmsg == NULL \|\| cmsg->cmsg_type != SCM_CREDENTIALS) {
	222	log_info(udev_monitor->udev, "no sender credentials received, message ignored");
	223	return NULL;
	224	}
	225
	226	if (cred->uid != 0) {
	227	log_info(udev_monitor->udev, "sender uid=%d, message ignored", cred->uid);
	228	return NULL;
	229	}
	230
	231	/* skip header */
	232	bufpos = strlen(buf) + 1;
	233	if (bufpos < sizeof("a@/d") \|\| bufpos >= sizeof(buf)) {
	234	log_info(udev_monitor->udev, "invalid message length");
	235	return NULL;
	236	}
	237
	238	/* check message header */
	239	if (strstr(buf, "@/") == NULL) {
	240	log_info(udev_monitor->udev, "unrecognized message header");
	241	return NULL;
	242	}
	243
	244	udev_device = device_init(udev_monitor->udev);
	245	if (udev_device == NULL) {
	246	return NULL;
	247	}
	248
	249	while (bufpos < sizeof(buf)) {
	250	char *key;
	251	size_t keylen;
	252
	253	key = &buf[bufpos];
	254	keylen = strlen(key);
255	if (keylen == 0)
256	break;
257	bufpos += keylen + 1;
258
259	if (strncmp(key, "DEVPATH=", 8) == 0) {
260	udev_device->devpath = strdup(&key[8]);
261	} else if (strncmp(key, "SUBSYSTEM=", 10) == 0) {
262	udev_device->subsystem = strdup(&key[10]);
263	} else if (strncmp(key, "DEVNAME=", 8) == 0) {
264	udev_device->devname = strdup(&key[8]);
265	} else if (strncmp(key, "DEVLINKS=", 9) == 0) {
266	char *slink = &key[9];
267	char *next = strchr(slink, ' ');
268
269	while (next != NULL) {
270	next[0] = '\0';
271	name_list_add(&udev_device->link_list, slink, 0);
272	slink = &next[1];
273	next = strchr(slink, ' ');
274	}
275	if (slink[0] != '\0')
276	name_list_add(&udev_device->link_list, slink, 0);
277	}
278	name_list_add(&udev_device->env_list, key, 0);
279	}
280
281	return udev_device;
282	}