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Systemd/src/libsystemd-network/sd-ndisc.c

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/***
This file is part of systemd.
Copyright (C) 2014 Intel Corporation. All rights reserved.
systemd 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.
systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <netinet/icmp6.h>
#include <netinet/in.h>
#include "sd-ndisc.h"
#include "alloc-util.h"
#include "fd-util.h"
#include "icmp6-util.h"
#include "in-addr-util.h"
#include "ndisc-internal.h"
#include "ndisc-router.h"
#include "socket-util.h"
#include "string-util.h"
#include "util.h"
#define NDISC_ROUTER_SOLICITATION_INTERVAL (4U * USEC_PER_SEC)
#define NDISC_MAX_ROUTER_SOLICITATIONS 3U
static void ndisc_callback(sd_ndisc *ndisc, sd_ndisc_event event, sd_ndisc_router *rt) {
assert(ndisc);
log_ndisc("Invoking callback for '%c'.", event);
if (!ndisc->callback)
return;
ndisc->callback(ndisc, event, rt, ndisc->userdata);
}
_public_ int sd_ndisc_set_callback(
sd_ndisc *nd,
sd_ndisc_callback_t callback,
void *userdata) {
assert_return(nd, -EINVAL);
nd->callback = callback;
nd->userdata = userdata;
return 0;
}
_public_ int sd_ndisc_set_ifindex(sd_ndisc *nd, int ifindex) {
assert_return(nd, -EINVAL);
assert_return(ifindex > 0, -EINVAL);
assert_return(nd->fd < 0, -EBUSY);
nd->ifindex = ifindex;
return 0;
}
_public_ int sd_ndisc_set_mac(sd_ndisc *nd, const struct ether_addr *mac_addr) {
assert_return(nd, -EINVAL);
if (mac_addr)
nd->mac_addr = *mac_addr;
else
zero(nd->mac_addr);
return 0;
}
_public_ int sd_ndisc_attach_event(sd_ndisc *nd, sd_event *event, int64_t priority) {
int r;
assert_return(nd, -EINVAL);
assert_return(nd->fd < 0, -EBUSY);
assert_return(!nd->event, -EBUSY);
if (event)
nd->event = sd_event_ref(event);
else {
r = sd_event_default(&nd->event);
if (r < 0)
return 0;
}
nd->event_priority = priority;
return 0;
}
_public_ int sd_ndisc_detach_event(sd_ndisc *nd) {
assert_return(nd, -EINVAL);
assert_return(nd->fd < 0, -EBUSY);
nd->event = sd_event_unref(nd->event);
return 0;
}
_public_ sd_event *sd_ndisc_get_event(sd_ndisc *nd) {
assert_return(nd, NULL);
return nd->event;
}
_public_ sd_ndisc *sd_ndisc_ref(sd_ndisc *nd) {
if (!nd)
return NULL;
assert(nd->n_ref > 0);
nd->n_ref++;
return nd;
}
static int ndisc_reset(sd_ndisc *nd) {
assert(nd);
nd->timeout_event_source = sd_event_source_unref(nd->timeout_event_source);
nd->recv_event_source = sd_event_source_unref(nd->recv_event_source);
nd->fd = safe_close(nd->fd);
return 0;
}
_public_ sd_ndisc *sd_ndisc_unref(sd_ndisc *nd) {
if (!nd)
return NULL;
assert(nd->n_ref > 0);
nd->n_ref--;
if (nd->n_ref > 0)
return NULL;
ndisc_reset(nd);
sd_ndisc_detach_event(nd);
return mfree(nd);
}
_public_ int sd_ndisc_new(sd_ndisc **ret) {
_cleanup_(sd_ndisc_unrefp) sd_ndisc *nd = NULL;
assert_return(ret, -EINVAL);
nd = new0(sd_ndisc, 1);
if (!nd)
return -ENOMEM;
nd->n_ref = 1;
nd->fd = -1;
*ret = nd;
nd = NULL;
return 0;
}
_public_ int sd_ndisc_get_mtu(sd_ndisc *nd, uint32_t *mtu) {
assert_return(nd, -EINVAL);
assert_return(mtu, -EINVAL);
if (nd->mtu == 0)
return -ENODATA;
*mtu = nd->mtu;
return 0;
}
_public_ int sd_ndisc_get_hop_limit(sd_ndisc *nd, uint8_t *ret) {
assert_return(nd, -EINVAL);
assert_return(ret, -EINVAL);
if (nd->hop_limit == 0)
return -ENODATA;
*ret = nd->hop_limit;
return 0;
}
static int ndisc_handle_datagram(sd_ndisc *nd, sd_ndisc_router *rt) {
int r;
assert(nd);
assert(rt);
r = ndisc_router_parse(rt);
if (r == -EBADMSG) /* Bad packet */
return 0;
if (r < 0)
return 0;
/* Update global variables we keep */
if (rt->mtu > 0)
nd->mtu = rt->mtu;
if (rt->hop_limit > 0)
nd->hop_limit = rt->hop_limit;
log_ndisc("Received Router Advertisement: flags %s preference %s lifetime %" PRIu16 " sec",
rt->flags & ND_RA_FLAG_MANAGED ? "MANAGED" : rt->flags & ND_RA_FLAG_OTHER ? "OTHER" : "none",
rt->preference == SD_NDISC_PREFERENCE_HIGH ? "high" : rt->preference == SD_NDISC_PREFERENCE_LOW ? "low" : "medium",
rt->lifetime);
ndisc_callback(nd, SD_NDISC_EVENT_ROUTER, rt);
return 0;
}
static int ndisc_recv(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
_cleanup_(sd_ndisc_router_unrefp) sd_ndisc_router *rt = NULL;
sd_ndisc *nd = userdata;
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(int)) + /* ttl */
CMSG_SPACE(sizeof(struct timeval))];
} control = {};
struct iovec iov = {};
union sockaddr_union sa = {};
struct msghdr msg = {
.msg_name = &sa.sa,
.msg_namelen = sizeof(sa),
.msg_iov = &iov,
.msg_iovlen = 1,
.msg_control = &control,
.msg_controllen = sizeof(control),
};
struct cmsghdr *cmsg;
ssize_t len, buflen;
assert(s);
assert(nd);
assert(nd->event);
buflen = next_datagram_size_fd(fd);
if (buflen < 0)
return log_ndisc_errno(buflen, "Failed to determine datagram size to read: %m");
rt = ndisc_router_new(buflen);
if (!rt)
return -ENOMEM;
iov.iov_base = NDISC_ROUTER_RAW(rt);
iov.iov_len = rt->raw_size;
len = recvmsg(fd, &msg, MSG_DONTWAIT);
if (len < 0) {
if (errno == EAGAIN || errno == EINTR)
return 0;
return log_ndisc_errno(errno, "Could not receive message from ICMPv6 socket: %m");
}
if ((size_t) len != rt->raw_size) {
log_ndisc("Packet size mismatch.");
return -EINVAL;
}
if (msg.msg_namelen == sizeof(struct sockaddr_in6) &&
sa.in6.sin6_family == AF_INET6) {
if (in_addr_is_link_local(AF_INET6, (union in_addr_union*) &sa.in6.sin6_addr) <= 0) {
_cleanup_free_ char *addr = NULL;
(void) in_addr_to_string(AF_INET6, (union in_addr_union*) &sa.in6.sin6_addr, &addr);
log_ndisc("Received RA from non-link-local address %s. Ignoring.", strna(addr));
return 0;
}
rt->address = sa.in6.sin6_addr;
} else if (msg.msg_namelen > 0) {
log_ndisc("Received invalid source address size from ICMPv6 socket: %zu bytes", (size_t) msg.msg_namelen);
return -EINVAL;
}
/* namelen == 0 only happens when running the test-suite over a socketpair */
assert(!(msg.msg_flags & MSG_CTRUNC));
assert(!(msg.msg_flags & MSG_TRUNC));
CMSG_FOREACH(cmsg, &msg) {
if (cmsg->cmsg_level == SOL_IPV6 &&
cmsg->cmsg_type == IPV6_HOPLIMIT &&
cmsg->cmsg_len == CMSG_LEN(sizeof(int))) {
int hops = *(int*) CMSG_DATA(cmsg);
if (hops != 255) {
log_ndisc("Received RA with invalid hop limit %d. Ignoring.", hops);
return 0;
}
}
if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SO_TIMESTAMP &&
cmsg->cmsg_len == CMSG_LEN(sizeof(struct timeval)))
triple_timestamp_from_realtime(&rt->timestamp, timeval_load((struct timeval*) CMSG_DATA(cmsg)));
}
if (!triple_timestamp_is_set(&rt->timestamp))
triple_timestamp_get(&rt->timestamp);
nd->timeout_event_source = sd_event_source_unref(nd->timeout_event_source);
return ndisc_handle_datagram(nd, rt);
}
static int ndisc_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
sd_ndisc *nd = userdata;
usec_t time_now, next_timeout;
int r;
assert(s);
assert(nd);
assert(nd->event);
if (nd->nd_sent >= NDISC_MAX_ROUTER_SOLICITATIONS) {
nd->timeout_event_source = sd_event_source_unref(nd->timeout_event_source);
ndisc_callback(nd, SD_NDISC_EVENT_TIMEOUT, NULL);
return 0;
}
r = icmp6_send_router_solicitation(nd->fd, &nd->mac_addr);
if (r < 0) {
log_ndisc_errno(r, "Error sending Router Solicitation: %m");
goto fail;
}
log_ndisc("Sent Router Solicitation");
nd->nd_sent++;
assert_se(sd_event_now(nd->event, clock_boottime_or_monotonic(), &time_now) >= 0);
next_timeout = time_now + NDISC_ROUTER_SOLICITATION_INTERVAL;
r = sd_event_source_set_time(nd->timeout_event_source, next_timeout);
if (r < 0) {
log_ndisc_errno(r, "Error updating timer: %m");
goto fail;
}
r = sd_event_source_set_enabled(nd->timeout_event_source, SD_EVENT_ONESHOT);
if (r < 0) {
log_ndisc_errno(r, "Error reenabling timer: %m");
goto fail;
}
return 0;
fail:
sd_ndisc_stop(nd);
return 0;
}
_public_ int sd_ndisc_stop(sd_ndisc *nd) {
assert_return(nd, -EINVAL);
if (nd->fd < 0)
return 0;
log_ndisc("Stopping IPv6 Router Solicitation client");
ndisc_reset(nd);
return 1;
}
_public_ int sd_ndisc_start(sd_ndisc *nd) {
int r;
assert_return(nd, -EINVAL);
assert_return(nd->event, -EINVAL);
assert_return(nd->ifindex > 0, -EINVAL);
if (nd->fd >= 0)
return 0;
assert(!nd->recv_event_source);
assert(!nd->timeout_event_source);
nd->fd = icmp6_bind_router_solicitation(nd->ifindex);
if (nd->fd < 0)
return nd->fd;
r = sd_event_add_io(nd->event, &nd->recv_event_source, nd->fd, EPOLLIN, ndisc_recv, nd);
if (r < 0)
goto fail;
r = sd_event_source_set_priority(nd->recv_event_source, nd->event_priority);
if (r < 0)
goto fail;
(void) sd_event_source_set_description(nd->recv_event_source, "ndisc-receive-message");
r = sd_event_add_time(nd->event, &nd->timeout_event_source, clock_boottime_or_monotonic(), 0, 0, ndisc_timeout, nd);
if (r < 0)
goto fail;
r = sd_event_source_set_priority(nd->timeout_event_source, nd->event_priority);
if (r < 0)
goto fail;
(void) sd_event_source_set_description(nd->timeout_event_source, "ndisc-timeout");
log_ndisc("Started IPv6 Router Solicitation client");
return 1;
fail:
ndisc_reset(nd);
return r;
}
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