Initial

1 files changed, 401 insertions, 0 deletions

diff --git a/src/os/linux_netlink.c b/src/os/linux_netlink.c
new file mode 100644
index 0000000..899084f
--- /dev/null
+++ b/src/os/linux_netlink.c
@@ -0,0 +1,401 @@
+/* -*- Mode: C; c-basic-offset:8 ; indent-tabs-mode:t -*- */
+/*
+ * Linux usbfs backend for libusb
+ * Copyright (C) 2007-2009 Daniel Drake <dsd@gentoo.org>
+ * Copyright (c) 2001 Johannes Erdfelt <johannes@erdfelt.com>
+ * Copyright (c) 2013 Nathan Hjelm <hjelmn@mac.com>
+ * Copyright (c) 2016 Chris Dickens <christopher.a.dickens@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libusbi.h"
+#include "linux_usbfs.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <pthread.h>
+#include <string.h>
+#include <unistd.h>
+
+#ifdef HAVE_ASM_TYPES_H
+#include <asm/types.h>
+#endif
+#include <sys/socket.h>
+#include <linux/netlink.h>
+
+#define NL_GROUP_KERNEL 1
+
+#ifndef SOCK_CLOEXEC
+#define SOCK_CLOEXEC	0
+#endif
+
+#ifndef SOCK_NONBLOCK
+#define SOCK_NONBLOCK	0
+#endif
+
+static int linux_netlink_socket = -1;
+static usbi_event_t netlink_control_event = USBI_INVALID_EVENT;
+static pthread_t libusb_linux_event_thread;
+
+static void *linux_netlink_event_thread_main(void *arg);
+
+static int set_fd_cloexec_nb(int fd, int socktype)
+{
+	int flags;
+
+#if defined(FD_CLOEXEC)
+	/* Make sure the netlink socket file descriptor is marked as CLOEXEC */
+	if (!(socktype & SOCK_CLOEXEC)) {
+		flags = fcntl(fd, F_GETFD);
+		if (flags == -1) {
+			usbi_err(NULL, "failed to get netlink fd flags, errno=%d", errno);
+			return -1;
+		}
+
+		if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) == -1) {
+			usbi_err(NULL, "failed to set netlink fd flags, errno=%d", errno);
+			return -1;
+		}
+	}
+#endif
+
+	/* Make sure the netlink socket is non-blocking */
+	if (!(socktype & SOCK_NONBLOCK)) {
+		flags = fcntl(fd, F_GETFL);
+		if (flags == -1) {
+			usbi_err(NULL, "failed to get netlink fd status flags, errno=%d", errno);
+			return -1;
+		}
+
+		if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1) {
+			usbi_err(NULL, "failed to set netlink fd status flags, errno=%d", errno);
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+int linux_netlink_start_event_monitor(void)
+{
+	struct sockaddr_nl sa_nl = { .nl_family = AF_NETLINK, .nl_groups = NL_GROUP_KERNEL };
+	int socktype = SOCK_RAW | SOCK_NONBLOCK | SOCK_CLOEXEC;
+	int opt = 1;
+	int ret;
+
+	linux_netlink_socket = socket(PF_NETLINK, socktype, NETLINK_KOBJECT_UEVENT);
+	if (linux_netlink_socket == -1 && errno == EINVAL) {
+		usbi_dbg(NULL, "failed to create netlink socket of type %d, attempting SOCK_RAW", socktype);
+		socktype = SOCK_RAW;
+		linux_netlink_socket = socket(PF_NETLINK, socktype, NETLINK_KOBJECT_UEVENT);
+	}
+
+	if (linux_netlink_socket == -1) {
+		usbi_err(NULL, "failed to create netlink socket, errno=%d", errno);
+		goto err;
+	}
+
+	ret = set_fd_cloexec_nb(linux_netlink_socket, socktype);
+	if (ret == -1)
+		goto err_close_socket;
+
+	ret = bind(linux_netlink_socket, (struct sockaddr *)&sa_nl, sizeof(sa_nl));
+	if (ret == -1) {
+		usbi_err(NULL, "failed to bind netlink socket, errno=%d", errno);
+		goto err_close_socket;
+	}
+
+	ret = setsockopt(linux_netlink_socket, SOL_SOCKET, SO_PASSCRED, &opt, sizeof(opt));
+	if (ret == -1) {
+		usbi_err(NULL, "failed to set netlink socket SO_PASSCRED option, errno=%d", errno);
+		goto err_close_socket;
+	}
+
+	ret = usbi_create_event(&netlink_control_event);
+	if (ret) {
+		usbi_err(NULL, "failed to create netlink control event");
+		goto err_close_socket;
+	}
+
+	ret = pthread_create(&libusb_linux_event_thread, NULL, linux_netlink_event_thread_main, NULL);
+	if (ret != 0) {
+		usbi_err(NULL, "failed to create netlink event thread (%d)", ret);
+		goto err_destroy_event;
+	}
+
+	return LIBUSB_SUCCESS;
+
+err_destroy_event:
+	usbi_destroy_event(&netlink_control_event);
+	netlink_control_event = (usbi_event_t)USBI_INVALID_EVENT;
+err_close_socket:
+	close(linux_netlink_socket);
+	linux_netlink_socket = -1;
+err:
+	return LIBUSB_ERROR_OTHER;
+}
+
+int linux_netlink_stop_event_monitor(void)
+{
+	int ret;
+
+	assert(linux_netlink_socket != -1);
+
+	/* Signal the control event and wait for the thread to exit */
+	usbi_signal_event(&netlink_control_event);
+
+	ret = pthread_join(libusb_linux_event_thread, NULL);
+	if (ret)
+		usbi_warn(NULL, "failed to join netlink event thread (%d)", ret);
+
+	usbi_destroy_event(&netlink_control_event);
+	netlink_control_event = (usbi_event_t)USBI_INVALID_EVENT;
+
+	close(linux_netlink_socket);
+	linux_netlink_socket = -1;
+
+	return LIBUSB_SUCCESS;
+}
+
+static const char *netlink_message_parse(const char *buffer, size_t len, const char *key)
+{
+	const char *end = buffer + len;
+	size_t keylen = strlen(key);
+
+	while (buffer < end && *buffer) {
+		if (strncmp(buffer, key, keylen) == 0 && buffer[keylen] == '=')
+			return buffer + keylen + 1;
+		buffer += strlen(buffer) + 1;
+	}
+
+	return NULL;
+}
+
+/* parse parts of netlink message common to both libudev and the kernel */
+static int linux_netlink_parse(const char *buffer, size_t len, int *detached,
+	const char **sys_name, uint8_t *busnum, uint8_t *devaddr)
+{
+	const char *tmp, *slash;
+
+	errno = 0;
+
+	*sys_name = NULL;
+	*detached = 0;
+	*busnum   = 0;
+	*devaddr  = 0;
+
+	tmp = netlink_message_parse(buffer, len, "ACTION");
+	if (!tmp) {
+		return -1;
+	} else if (strcmp(tmp, "remove") == 0) {
+		*detached = 1;
+	} else if (strcmp(tmp, "add") != 0) {
+		usbi_dbg(NULL, "unknown device action %s", tmp);
+		return -1;
+	}
+
+	/* check that this is a usb message */
+	tmp = netlink_message_parse(buffer, len, "SUBSYSTEM");
+	if (!tmp || strcmp(tmp, "usb") != 0) {
+		/* not usb. ignore */
+		return -1;
+	}
+
+	/* check that this is an actual usb device */
+	tmp = netlink_message_parse(buffer, len, "DEVTYPE");
+	if (!tmp || strcmp(tmp, "usb_device") != 0) {
+		/* not usb. ignore */
+		return -1;
+	}
+
+	tmp = netlink_message_parse(buffer, len, "BUSNUM");
+	if (tmp) {
+		*busnum = (uint8_t)(strtoul(tmp, NULL, 10) & 0xff);
+		if (errno) {
+			errno = 0;
+			return -1;
+		}
+
+		tmp = netlink_message_parse(buffer, len, "DEVNUM");
+		if (NULL == tmp)
+			return -1;
+
+		*devaddr = (uint8_t)(strtoul(tmp, NULL, 10) & 0xff);
+		if (errno) {
+			errno = 0;
+			return -1;
+		}
+	} else {
+		/* no bus number. try "DEVICE" */
+		tmp = netlink_message_parse(buffer, len, "DEVICE");
+		if (!tmp) {
+			/* not usb. ignore */
+			return -1;
+		}
+
+		/* Parse a device path such as /dev/bus/usb/003/004 */
+		slash = strrchr(tmp, '/');
+		if (!slash)
+			return -1;
+
+		*busnum = (uint8_t)(strtoul(slash - 3, NULL, 10) & 0xff);
+		if (errno) {
+			errno = 0;
+			return -1;
+		}
+
+		*devaddr = (uint8_t)(strtoul(slash + 1, NULL, 10) & 0xff);
+		if (errno) {
+			errno = 0;
+			return -1;
+		}
+
+		return 0;
+	}
+
+	tmp = netlink_message_parse(buffer, len, "DEVPATH");
+	if (!tmp)
+		return -1;
+
+	slash = strrchr(tmp, '/');
+	if (slash)
+		*sys_name = slash + 1;
+
+	/* found a usb device */
+	return 0;
+}
+
+static int linux_netlink_read_message(void)
+{
+	char cred_buffer[CMSG_SPACE(sizeof(struct ucred))];
+	char msg_buffer[2048];
+	const char *sys_name = NULL;
+	uint8_t busnum, devaddr;
+	int detached, r;
+	ssize_t len;
+	struct cmsghdr *cmsg;
+	struct ucred *cred;
+	struct sockaddr_nl sa_nl;
+	struct iovec iov = { .iov_base = msg_buffer, .iov_len = sizeof(msg_buffer) };
+	struct msghdr msg = {
+		.msg_iov = &iov, .msg_iovlen = 1,
+		.msg_control = cred_buffer, .msg_controllen = sizeof(cred_buffer),
+		.msg_name = &sa_nl, .msg_namelen = sizeof(sa_nl)
+	};
+
+	/* read netlink message */
+	len = recvmsg(linux_netlink_socket, &msg, 0);
+	if (len == -1) {
+		if (errno != EAGAIN && errno != EINTR)
+			usbi_err(NULL, "error receiving message from netlink, errno=%d", errno);
+		return -1;
+	}
+
+	if (len < 32 || (msg.msg_flags & MSG_TRUNC)) {
+		usbi_err(NULL, "invalid netlink message length");
+		return -1;
+	}
+
+	if (sa_nl.nl_groups != NL_GROUP_KERNEL || sa_nl.nl_pid != 0) {
+		usbi_dbg(NULL, "ignoring netlink message from unknown group/PID (%u/%u)",
+			 (unsigned int)sa_nl.nl_groups, (unsigned int)sa_nl.nl_pid);
+		return -1;
+	}
+
+	cmsg = CMSG_FIRSTHDR(&msg);
+	if (!cmsg || cmsg->cmsg_type != SCM_CREDENTIALS) {
+		usbi_dbg(NULL, "ignoring netlink message with no sender credentials");
+		return -1;
+	}
+
+	cred = (struct ucred *)CMSG_DATA(cmsg);
+	if (cred->uid != 0) {
+		usbi_dbg(NULL, "ignoring netlink message with non-zero sender UID %u", (unsigned int)cred->uid);
+		return -1;
+	}
+
+	r = linux_netlink_parse(msg_buffer, (size_t)len, &detached, &sys_name, &busnum, &devaddr);
+	if (r)
+		return r;
+
+	usbi_dbg(NULL, "netlink hotplug found device busnum: %hhu, devaddr: %hhu, sys_name: %s, removed: %s",
+		 busnum, devaddr, sys_name, detached ? "yes" : "no");
+
+	/* signal device is available (or not) to all contexts */
+	if (detached)
+		linux_device_disconnected(busnum, devaddr);
+	else
+		linux_hotplug_enumerate(busnum, devaddr, sys_name);
+
+	return 0;
+}
+
+static void *linux_netlink_event_thread_main(void *arg)
+{
+	struct pollfd fds[] = {
+		{ .fd = USBI_EVENT_OS_HANDLE(&netlink_control_event),
+		  .events = USBI_EVENT_POLL_EVENTS },
+		{ .fd = linux_netlink_socket,
+		  .events = POLLIN },
+	};
+	int r;
+
+	UNUSED(arg);
+
+#if defined(HAVE_PTHREAD_SETNAME_NP)
+	r = pthread_setname_np(pthread_self(), "libusb_event");
+	if (r)
+		usbi_warn(NULL, "failed to set hotplug event thread name, error=%d", r);
+#endif
+
+	usbi_dbg(NULL, "netlink event thread entering");
+
+	while (1) {
+		r = poll(fds, 2, -1);
+		if (r == -1) {
+			/* check for temporary failure */
+			if (errno == EINTR)
+				continue;
+			usbi_err(NULL, "poll() failed, errno=%d", errno);
+			break;
+		}
+		if (fds[0].revents) {
+			/* activity on control event, exit */
+			break;
+		}
+		if (fds[1].revents) {
+			usbi_mutex_static_lock(&linux_hotplug_lock);
+			linux_netlink_read_message();
+			usbi_mutex_static_unlock(&linux_hotplug_lock);
+		}
+	}
+
+	usbi_dbg(NULL, "netlink event thread exiting");
+
+	return NULL;
+}
+
+void linux_netlink_hotplug_poll(void)
+{
+	int r;
+
+	usbi_mutex_static_lock(&linux_hotplug_lock);
+	do {
+		r = linux_netlink_read_message();
+	} while (r == 0);
+	usbi_mutex_static_unlock(&linux_hotplug_lock);
+}