diff options
Diffstat (limited to 'src/udev/udev-ctrl.c')
| -rw-r--r-- | src/udev/udev-ctrl.c | 393 |
1 files changed, 393 insertions, 0 deletions
diff --git a/src/udev/udev-ctrl.c b/src/udev/udev-ctrl.c new file mode 100644 index 0000000..48355aa --- /dev/null +++ b/src/udev/udev-ctrl.c @@ -0,0 +1,393 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later + * + * libudev - interface to udev device information + * + * 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. + */ + +#include <errno.h> +#include <poll.h> +#include <stddef.h> +#include <stdlib.h> +#include <string.h> +#include <sys/un.h> +#include <unistd.h> + +#include "sd-event.h" + +#include "alloc-util.h" +#include "errno-util.h" +#include "fd-util.h" +#include "format-util.h" +#include "io-util.h" +#include "socket-util.h" +#include "strxcpyx.h" +#include "udev-ctrl.h" +#include "util.h" + +/* wire protocol magic must match */ +#define UDEV_CTRL_MAGIC 0xdead1dea + +struct udev_ctrl_msg_wire { + char version[16]; + unsigned magic; + enum udev_ctrl_msg_type type; + union udev_ctrl_msg_value value; +}; + +struct udev_ctrl { + unsigned n_ref; + int sock; + int sock_connect; + union sockaddr_union saddr; + socklen_t addrlen; + bool bound:1; + bool cleanup_socket:1; + bool connected:1; + bool maybe_disconnected:1; + sd_event *event; + sd_event_source *event_source; + sd_event_source *event_source_connect; + udev_ctrl_handler_t callback; + void *userdata; +}; + +int udev_ctrl_new_from_fd(struct udev_ctrl **ret, int fd) { + _cleanup_close_ int sock = -1; + struct udev_ctrl *uctrl; + + assert(ret); + + if (fd < 0) { + sock = socket(AF_LOCAL, SOCK_SEQPACKET|SOCK_NONBLOCK|SOCK_CLOEXEC, 0); + if (sock < 0) + return log_error_errno(errno, "Failed to create socket: %m"); + } + + uctrl = new(struct udev_ctrl, 1); + if (!uctrl) + return -ENOMEM; + + *uctrl = (struct udev_ctrl) { + .n_ref = 1, + .sock = fd >= 0 ? fd : TAKE_FD(sock), + .sock_connect = -1, + .bound = fd >= 0, + }; + + uctrl->saddr.un = (struct sockaddr_un) { + .sun_family = AF_UNIX, + .sun_path = "/run/udev/control", + }; + + uctrl->addrlen = SOCKADDR_UN_LEN(uctrl->saddr.un); + + *ret = TAKE_PTR(uctrl); + return 0; +} + +int udev_ctrl_enable_receiving(struct udev_ctrl *uctrl) { + int r; + + assert(uctrl); + + if (uctrl->bound) + return 0; + + r = bind(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen); + if (r < 0 && errno == EADDRINUSE) { + (void) sockaddr_un_unlink(&uctrl->saddr.un); + r = bind(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen); + } + + if (r < 0) + return log_error_errno(errno, "Failed to bind udev control socket: %m"); + + if (listen(uctrl->sock, 0) < 0) + return log_error_errno(errno, "Failed to listen udev control socket: %m"); + + uctrl->bound = true; + uctrl->cleanup_socket = true; + + return 0; +} + +static void udev_ctrl_disconnect(struct udev_ctrl *uctrl) { + if (!uctrl) + return; + + uctrl->event_source_connect = sd_event_source_unref(uctrl->event_source_connect); + uctrl->sock_connect = safe_close(uctrl->sock_connect); +} + +static struct udev_ctrl *udev_ctrl_free(struct udev_ctrl *uctrl) { + assert(uctrl); + + udev_ctrl_disconnect(uctrl); + + sd_event_source_unref(uctrl->event_source); + safe_close(uctrl->sock); + + sd_event_unref(uctrl->event); + return mfree(uctrl); +} + +DEFINE_TRIVIAL_REF_UNREF_FUNC(struct udev_ctrl, udev_ctrl, udev_ctrl_free); + +int udev_ctrl_cleanup(struct udev_ctrl *uctrl) { + if (!uctrl) + return 0; + if (uctrl->cleanup_socket) + sockaddr_un_unlink(&uctrl->saddr.un); + return 0; +} + +int udev_ctrl_attach_event(struct udev_ctrl *uctrl, sd_event *event) { + int r; + + assert_return(uctrl, -EINVAL); + assert_return(!uctrl->event, -EBUSY); + + if (event) + uctrl->event = sd_event_ref(event); + else { + r = sd_event_default(&uctrl->event); + if (r < 0) + return r; + } + + return 0; +} + +sd_event_source *udev_ctrl_get_event_source(struct udev_ctrl *uctrl) { + assert(uctrl); + + return uctrl->event_source; +} + +static void udev_ctrl_disconnect_and_listen_again(struct udev_ctrl *uctrl) { + udev_ctrl_disconnect(uctrl); + udev_ctrl_unref(uctrl); + (void) sd_event_source_set_enabled(uctrl->event_source, SD_EVENT_ON); +} + +DEFINE_TRIVIAL_CLEANUP_FUNC(struct udev_ctrl *, udev_ctrl_disconnect_and_listen_again); + +static int udev_ctrl_connection_event_handler(sd_event_source *s, int fd, uint32_t revents, void *userdata) { + _cleanup_(udev_ctrl_disconnect_and_listen_againp) struct udev_ctrl *uctrl = NULL; + struct udev_ctrl_msg_wire msg_wire; + struct iovec iov = IOVEC_MAKE(&msg_wire, sizeof(struct udev_ctrl_msg_wire)); + CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct ucred))) control; + struct msghdr smsg = { + .msg_iov = &iov, + .msg_iovlen = 1, + .msg_control = &control, + .msg_controllen = sizeof(control), + }; + struct cmsghdr *cmsg; + struct ucred *cred; + ssize_t size; + + assert(userdata); + + /* When UDEV_CTRL_EXIT is received, manager unref udev_ctrl object. + * To avoid the object freed, let's increment the refcount. */ + uctrl = udev_ctrl_ref(userdata); + + size = next_datagram_size_fd(fd); + if (size < 0) + return log_error_errno(size, "Failed to get size of message: %m"); + if (size == 0) + return 0; /* Client disconnects? */ + + size = recvmsg_safe(fd, &smsg, 0); + if (size == -EINTR) + return 0; + if (size < 0) + return log_error_errno(size, "Failed to receive ctrl message: %m"); + + cmsg_close_all(&smsg); + + cmsg = CMSG_FIRSTHDR(&smsg); + + if (!cmsg || cmsg->cmsg_type != SCM_CREDENTIALS) { + log_error("No sender credentials received, ignoring message"); + return 0; + } + + cred = (struct ucred *) CMSG_DATA(cmsg); + + if (cred->uid != 0) { + log_error("Invalid sender uid "UID_FMT", ignoring message", cred->uid); + return 0; + } + + if (msg_wire.magic != UDEV_CTRL_MAGIC) { + log_error("Message magic 0x%08x doesn't match, ignoring message", msg_wire.magic); + return 0; + } + + if (msg_wire.type == _UDEV_CTRL_END_MESSAGES) + return 0; + + if (uctrl->callback) + (void) uctrl->callback(uctrl, msg_wire.type, &msg_wire.value, uctrl->userdata); + + /* Do not disconnect and wait for next message. */ + uctrl = udev_ctrl_unref(uctrl); + return 0; +} + +static int udev_ctrl_event_handler(sd_event_source *s, int fd, uint32_t revents, void *userdata) { + struct udev_ctrl *uctrl = userdata; + _cleanup_close_ int sock = -1; + struct ucred ucred; + int r; + + assert(uctrl); + + sock = accept4(fd, NULL, NULL, SOCK_CLOEXEC|SOCK_NONBLOCK); + if (sock < 0) { + if (ERRNO_IS_ACCEPT_AGAIN(errno)) + return 0; + + return log_error_errno(errno, "Failed to accept ctrl connection: %m"); + } + + /* check peer credential of connection */ + r = getpeercred(sock, &ucred); + if (r < 0) { + log_error_errno(r, "Failed to receive credentials of ctrl connection: %m"); + return 0; + } + + if (ucred.uid > 0) { + log_error("Invalid sender uid "UID_FMT", closing connection", ucred.uid); + return 0; + } + + /* enable receiving of the sender credentials in the messages */ + r = setsockopt_int(sock, SOL_SOCKET, SO_PASSCRED, true); + if (r < 0) + log_warning_errno(r, "Failed to set SO_PASSCRED, ignoring: %m"); + + r = sd_event_add_io(uctrl->event, &uctrl->event_source_connect, sock, EPOLLIN, udev_ctrl_connection_event_handler, uctrl); + if (r < 0) { + log_error_errno(r, "Failed to create event source for udev control connection: %m"); + return 0; + } + + (void) sd_event_source_set_description(uctrl->event_source_connect, "udev-ctrl-connection"); + + /* Do not accept multiple connection. */ + (void) sd_event_source_set_enabled(uctrl->event_source, SD_EVENT_OFF); + + uctrl->sock_connect = TAKE_FD(sock); + return 0; +} + +int udev_ctrl_start(struct udev_ctrl *uctrl, udev_ctrl_handler_t callback, void *userdata) { + int r; + + assert(uctrl); + + if (!uctrl->event) { + r = udev_ctrl_attach_event(uctrl, NULL); + if (r < 0) + return r; + } + + r = udev_ctrl_enable_receiving(uctrl); + if (r < 0) + return r; + + uctrl->callback = callback; + uctrl->userdata = userdata; + + r = sd_event_add_io(uctrl->event, &uctrl->event_source, uctrl->sock, EPOLLIN, udev_ctrl_event_handler, uctrl); + if (r < 0) + return r; + + (void) sd_event_source_set_description(uctrl->event_source, "udev-ctrl"); + + return 0; +} + +int udev_ctrl_send(struct udev_ctrl *uctrl, enum udev_ctrl_msg_type type, int intval, const char *buf) { + struct udev_ctrl_msg_wire ctrl_msg_wire = { + .version = "udev-" STRINGIFY(PROJECT_VERSION), + .magic = UDEV_CTRL_MAGIC, + .type = type, + }; + + if (uctrl->maybe_disconnected) + return -ENOANO; /* to distinguish this from other errors. */ + + if (buf) + strscpy(ctrl_msg_wire.value.buf, sizeof(ctrl_msg_wire.value.buf), buf); + else + ctrl_msg_wire.value.intval = intval; + + if (!uctrl->connected) { + if (connect(uctrl->sock, &uctrl->saddr.sa, uctrl->addrlen) < 0) + return -errno; + uctrl->connected = true; + } + + if (send(uctrl->sock, &ctrl_msg_wire, sizeof(ctrl_msg_wire), 0) < 0) + return -errno; + + if (type == UDEV_CTRL_EXIT) + uctrl->maybe_disconnected = true; + + return 0; +} + +int udev_ctrl_wait(struct udev_ctrl *uctrl, usec_t timeout) { + _cleanup_(sd_event_source_unrefp) sd_event_source *source_io = NULL, *source_timeout = NULL; + int r; + + assert(uctrl); + + if (uctrl->sock < 0) + return 0; + if (!uctrl->connected) + return 0; + + if (!uctrl->maybe_disconnected) { + r = udev_ctrl_send(uctrl, _UDEV_CTRL_END_MESSAGES, 0, NULL); + if (r < 0) + return r; + } + + if (timeout == 0) + return 0; + + if (!uctrl->event) { + r = udev_ctrl_attach_event(uctrl, NULL); + if (r < 0) + return r; + } + + r = sd_event_add_io(uctrl->event, &source_io, uctrl->sock, EPOLLIN, NULL, INT_TO_PTR(0)); + if (r < 0) + return r; + + (void) sd_event_source_set_description(source_io, "udev-ctrl-wait-io"); + + if (timeout != USEC_INFINITY) { + r = sd_event_add_time_relative( + uctrl->event, &source_timeout, clock_boottime_or_monotonic(), + timeout, + 0, NULL, INT_TO_PTR(-ETIMEDOUT)); + if (r < 0) + return r; + + (void) sd_event_source_set_description(source_timeout, "udev-ctrl-wait-timeout"); + } + + return sd_event_loop(uctrl->event); +} |