--- /dev/null
+/* -*- 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 <config.h>
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+#ifdef HAVE_ASM_TYPES_H
+#include <asm/types.h>
+#endif
+
+#include <sys/socket.h>
+#include <linux/netlink.h>
+
+#include "libusbi.h"
+#include "linux_usbfs.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 int netlink_control_pipe[2] = { -1, -1 };
+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 (%d)", errno);
+ return -1;
+ }
+
+ if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) == -1) {
+ usbi_err(NULL, "failed to set netlink fd flags (%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 (%d)", errno);
+ return -1;
+ }
+
+ if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1) {
+ usbi_err(NULL, "failed to set netlink fd status flags (%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("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 (%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 (%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 (%d)", errno);
+ goto err_close_socket;
+ }
+
+ ret = usbi_pipe(netlink_control_pipe);
+ if (ret) {
+ usbi_err(NULL, "failed to create netlink control pipe");
+ 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_close_pipe;
+ }
+
+ return LIBUSB_SUCCESS;
+
+err_close_pipe:
+ close(netlink_control_pipe[0]);
+ close(netlink_control_pipe[1]);
+ netlink_control_pipe[0] = -1;
+ netlink_control_pipe[1] = -1;
+err_close_socket:
+ close(linux_netlink_socket);
+ linux_netlink_socket = -1;
+err:
+ return LIBUSB_ERROR_OTHER;
+}
+
+int linux_netlink_stop_event_monitor(void)
+{
+ char dummy = 1;
+ ssize_t r;
+
+ assert(linux_netlink_socket != -1);
+
+ /* Write some dummy data to the control pipe and
+ * wait for the thread to exit */
+ r = write(netlink_control_pipe[1], &dummy, sizeof(dummy));
+ if (r <= 0)
+ usbi_warn(NULL, "netlink control pipe signal failed");
+
+ pthread_join(libusb_linux_event_thread, NULL);
+
+ close(linux_netlink_socket);
+ linux_netlink_socket = -1;
+
+ /* close and reset control pipe */
+ close(netlink_control_pipe[0]);
+ close(netlink_control_pipe[1]);
+ netlink_control_pipe[0] = -1;
+ netlink_control_pipe[1] = -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("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 (%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("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("ignoring netlink message with no sender credentials");
+ return -1;
+ }
+
+ cred = (struct ucred *)CMSG_DATA(cmsg);
+ if (cred->uid != 0) {
+ usbi_dbg("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("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)
+{
+ char dummy;
+ int r;
+ ssize_t nb;
+ struct pollfd fds[] = {
+ { .fd = netlink_control_pipe[0],
+ .events = POLLIN },
+ { .fd = linux_netlink_socket,
+ .events = POLLIN },
+ };
+
+ UNUSED(arg);
+
+ usbi_dbg("netlink event thread entering");
+
+ while ((r = poll(fds, 2, -1)) >= 0 || errno == EINTR) {
+ if (r < 0) {
+ /* temporary failure */
+ continue;
+ }
+ if (fds[0].revents & POLLIN) {
+ /* activity on control pipe, read the byte and exit */
+ nb = read(netlink_control_pipe[0], &dummy, sizeof(dummy));
+ if (nb <= 0)
+ usbi_warn(NULL, "netlink control pipe read failed");
+ break;
+ }
+ if (fds[1].revents & POLLIN) {
+ usbi_mutex_static_lock(&linux_hotplug_lock);
+ linux_netlink_read_message();
+ usbi_mutex_static_unlock(&linux_hotplug_lock);
+ }
+ }
+
+ usbi_dbg("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);
+}
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