| /* -*- 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 <linux/netlink.h> |
| #include <sys/socket.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("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("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("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) |
| { |
| 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("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("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); |
| } |