picnoir
/
Systemd
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity
Systemd/src/libsystemd-network/sd-ndisc.c

721 lines
21 KiB
C
Raw Blame History

/***
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 <netinet/ip6.h>
#include <stdbool.h>
#include <string.h>
#include <sys/ioctl.h>
#include "sd-ndisc.h"
#include "alloc-util.h"
#include "async.h"
#include "icmp6-util.h"
#include "in-addr-util.h"
#include "list.h"
#include "socket-util.h"
#include "string-util.h"
#define NDISC_ROUTER_SOLICITATION_INTERVAL 4 * USEC_PER_SEC
#define NDISC_MAX_ROUTER_SOLICITATIONS 3
enum NDiscState {
NDISC_STATE_IDLE,
NDISC_STATE_SOLICITATION_SENT,
NDISC_STATE_ADVERTISMENT_LISTEN,
_NDISC_STATE_MAX,
_NDISC_STATE_INVALID = -1,
};
#define IP6_MIN_MTU (unsigned)1280
#define ICMP6_RECV_SIZE (IP6_MIN_MTU - sizeof(struct ip6_hdr))
#define NDISC_OPT_LEN_UNITS 8
#define ND_RA_FLAG_PREF 0x18
#define ND_RA_FLAG_PREF_LOW 0x03
#define ND_RA_FLAG_PREF_MEDIUM 0x0
#define ND_RA_FLAG_PREF_HIGH 0x1
#define ND_RA_FLAG_PREF_INVALID 0x2
typedef struct NDiscPrefix NDiscPrefix;
struct NDiscPrefix {
unsigned n_ref;
sd_ndisc *nd;
LIST_FIELDS(NDiscPrefix, prefixes);
uint8_t len;
usec_t valid_until;
struct in6_addr addr;
};
struct sd_ndisc {
unsigned n_ref;
enum NDiscState state;
sd_event *event;
int event_priority;
int index;
struct ether_addr mac_addr;
uint32_t mtu;
LIST_HEAD(NDiscPrefix, prefixes);
int fd;
sd_event_source *recv;
sd_event_source *timeout;
int nd_sent;
sd_ndisc_router_callback_t router_callback;
sd_ndisc_prefix_autonomous_callback_t prefix_autonomous_callback;
sd_ndisc_prefix_onlink_callback_t prefix_onlink_callback;
sd_ndisc_callback_t callback;
void *userdata;
};
#define log_ndisc(p, fmt, ...) log_internal(LOG_DEBUG, 0, __FILE__, __LINE__, __func__, "NDisc CLIENT: " fmt, ##__VA_ARGS__)
static NDiscPrefix *ndisc_prefix_unref(NDiscPrefix *prefix) {
if (!prefix)
return NULL;
assert(prefix->n_ref > 0);
prefix->n_ref--;
if (prefix->n_ref > 0)
return NULL;
if (prefix->nd)
LIST_REMOVE(prefixes, prefix->nd->prefixes, prefix);
free(prefix);
return NULL;
}
static int ndisc_prefix_new(sd_ndisc *nd, NDiscPrefix **ret) {
_cleanup_free_ NDiscPrefix *prefix = NULL;
assert(ret);
prefix = new0(NDiscPrefix, 1);
if (!prefix)
return -ENOMEM;
prefix->n_ref = 1;
LIST_INIT(prefixes, prefix);
prefix->nd = nd;
*ret = prefix;
prefix = NULL;
return 0;
}
int sd_ndisc_set_callback(sd_ndisc *nd,
sd_ndisc_router_callback_t router_callback,
sd_ndisc_prefix_onlink_callback_t prefix_onlink_callback,
sd_ndisc_prefix_autonomous_callback_t prefix_autonomous_callback,
sd_ndisc_callback_t callback,
void *userdata) {
assert(nd);
nd->router_callback = router_callback;
nd->prefix_onlink_callback = prefix_onlink_callback;
nd->prefix_autonomous_callback = prefix_autonomous_callback;
nd->callback = callback;
nd->userdata = userdata;
return 0;
}
int sd_ndisc_set_index(sd_ndisc *nd, int interface_index) {
assert(nd);
assert(interface_index >= -1);
nd->index = interface_index;
return 0;
}
int sd_ndisc_set_mac(sd_ndisc *nd, const struct ether_addr *mac_addr) {
assert(nd);
if (mac_addr)
memcpy(&nd->mac_addr, mac_addr, sizeof(nd->mac_addr));
else
zero(nd->mac_addr);
return 0;
}
int sd_ndisc_attach_event(sd_ndisc *nd, sd_event *event, int priority) {
int r;
assert_return(nd, -EINVAL);
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;
}
int sd_ndisc_detach_event(sd_ndisc *nd) {
assert_return(nd, -EINVAL);
nd->event = sd_event_unref(nd->event);
return 0;
}
sd_event *sd_ndisc_get_event(sd_ndisc *nd) {
assert(nd);
return nd->event;
}
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_init(sd_ndisc *nd) {
assert(nd);
nd->recv = sd_event_source_unref(nd->recv);
nd->fd = asynchronous_close(nd->fd);
nd->timeout = sd_event_source_unref(nd->timeout);
return 0;
}
sd_ndisc *sd_ndisc_unref(sd_ndisc *nd) {
NDiscPrefix *prefix, *p;
if (!nd)
return NULL;
assert(nd->n_ref > 0);
nd->n_ref--;
if (nd->n_ref > 0)
return NULL;
ndisc_init(nd);
sd_ndisc_detach_event(nd);
LIST_FOREACH_SAFE(prefixes, prefix, p, nd->prefixes)
prefix = ndisc_prefix_unref(prefix);
free(nd);
return NULL;
}
int sd_ndisc_new(sd_ndisc **ret) {
_cleanup_(sd_ndisc_unrefp) sd_ndisc *nd = NULL;
assert(ret);
nd = new0(sd_ndisc, 1);
if (!nd)
return -ENOMEM;
nd->n_ref = 1;
nd->index = -1;
nd->fd = -1;
LIST_HEAD_INIT(nd->prefixes);
*ret = nd;
nd = NULL;
return 0;
}
int sd_ndisc_get_mtu(sd_ndisc *nd, uint32_t *mtu) {
assert_return(nd, -EINVAL);
assert_return(mtu, -EINVAL);
if (nd->mtu == 0)
return -ENOMSG;
*mtu = nd->mtu;
return 0;
}
static int prefix_match(const struct in6_addr *prefix, uint8_t prefixlen,
const struct in6_addr *addr,
uint8_t addr_prefixlen) {
uint8_t bytes, mask, len;
assert_return(prefix, -EINVAL);
assert_return(addr, -EINVAL);
len = MIN(prefixlen, addr_prefixlen);
bytes = len / 8;
mask = 0xff << (8 - len % 8);
if (memcmp(prefix, addr, bytes) != 0 ||
(prefix->s6_addr[bytes] & mask) != (addr->s6_addr[bytes] & mask))
return -EADDRNOTAVAIL;
return 0;
}
static int ndisc_prefix_match(sd_ndisc *nd, const struct in6_addr *addr,
uint8_t addr_len, NDiscPrefix **result) {
NDiscPrefix *prefix, *p;
usec_t time_now;
int r;
assert(nd);
r = sd_event_now(nd->event, clock_boottime_or_monotonic(), &time_now);
if (r < 0)
return r;
LIST_FOREACH_SAFE(prefixes, prefix, p, nd->prefixes) {
if (prefix->valid_until < time_now) {
prefix = ndisc_prefix_unref(prefix);
continue;
}
if (prefix_match(&prefix->addr, prefix->len, addr, addr_len) >= 0) {
*result = prefix;
return 0;
}
}
return -EADDRNOTAVAIL;
}
static int ndisc_prefix_update(sd_ndisc *nd, ssize_t len,
const struct nd_opt_prefix_info *prefix_opt) {
NDiscPrefix *prefix;
uint32_t lifetime_valid, lifetime_preferred;
usec_t time_now;
char time_string[FORMAT_TIMESPAN_MAX];
int r;
assert(nd);
assert(prefix_opt);
if (len < prefix_opt->nd_opt_pi_len)
return -ENOMSG;
if (!(prefix_opt->nd_opt_pi_flags_reserved & (ND_OPT_PI_FLAG_ONLINK | ND_OPT_PI_FLAG_AUTO)))
return 0;
if (in_addr_is_link_local(AF_INET6, (const union in_addr_union *) &prefix_opt->nd_opt_pi_prefix) > 0)
return 0;
lifetime_valid = be32toh(prefix_opt->nd_opt_pi_valid_time);
lifetime_preferred = be32toh(prefix_opt->nd_opt_pi_preferred_time);
if (lifetime_valid < lifetime_preferred)
return 0;
r = ndisc_prefix_match(nd, &prefix_opt->nd_opt_pi_prefix,
prefix_opt->nd_opt_pi_prefix_len, &prefix);
if (r < 0 && r != -EADDRNOTAVAIL)
return r;
/* if router advertisment prefix valid timeout is zero, the timeout
callback will be called immediately to clean up the prefix */
if (r == -EADDRNOTAVAIL) {
r = ndisc_prefix_new(nd, &prefix);
if (r < 0)
return r;
prefix->len = prefix_opt->nd_opt_pi_prefix_len;
memcpy(&prefix->addr, &prefix_opt->nd_opt_pi_prefix,
sizeof(prefix->addr));
log_ndisc(nd, "New prefix "SD_NDISC_ADDRESS_FORMAT_STR"/%d lifetime %d expires in %s",
SD_NDISC_ADDRESS_FORMAT_VAL(prefix->addr),
prefix->len, lifetime_valid,
format_timespan(time_string, FORMAT_TIMESPAN_MAX, lifetime_valid * USEC_PER_SEC, USEC_PER_SEC));
LIST_PREPEND(prefixes, nd->prefixes, prefix);
} else {
if (prefix->len != prefix_opt->nd_opt_pi_prefix_len) {
uint8_t prefixlen;
prefixlen = MIN(prefix->len, prefix_opt->nd_opt_pi_prefix_len);
log_ndisc(nd, "Prefix length mismatch %d/%d using %d",
prefix->len,
prefix_opt->nd_opt_pi_prefix_len,
prefixlen);
prefix->len = prefixlen;
}
log_ndisc(nd, "Update prefix "SD_NDISC_ADDRESS_FORMAT_STR"/%d lifetime %d expires in %s",
SD_NDISC_ADDRESS_FORMAT_VAL(prefix->addr),
prefix->len, lifetime_valid,
format_timespan(time_string, FORMAT_TIMESPAN_MAX, lifetime_valid * USEC_PER_SEC, USEC_PER_SEC));
}
r = sd_event_now(nd->event, clock_boottime_or_monotonic(), &time_now);
if (r < 0)
return r;
prefix->valid_until = time_now + lifetime_valid * USEC_PER_SEC;
if ((prefix_opt->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_ONLINK) && nd->prefix_onlink_callback)
nd->prefix_onlink_callback(nd, &prefix->addr, prefix->len, prefix->valid_until, nd->userdata);
if ((prefix_opt->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_AUTO) && nd->prefix_autonomous_callback)
nd->prefix_autonomous_callback(nd, &prefix->addr, prefix->len, lifetime_preferred, lifetime_valid,
nd->userdata);
return 0;
}
static int ndisc_ra_parse(sd_ndisc *nd, struct nd_router_advert *ra, ssize_t len) {
void *opt;
struct nd_opt_hdr *opt_hdr;
assert_return(nd, -EINVAL);
assert_return(ra, -EINVAL);
len -= sizeof(*ra);
if (len < NDISC_OPT_LEN_UNITS) {
log_ndisc(nd, "Router Advertisement below minimum length");
return -ENOMSG;
}
opt = ra + 1;
opt_hdr = opt;
while (len != 0 && len >= opt_hdr->nd_opt_len * NDISC_OPT_LEN_UNITS) {
struct nd_opt_mtu *opt_mtu;
uint32_t mtu;
struct nd_opt_prefix_info *opt_prefix;
if (opt_hdr->nd_opt_len == 0)
return -ENOMSG;
switch (opt_hdr->nd_opt_type) {
case ND_OPT_MTU:
opt_mtu = opt;
mtu = be32toh(opt_mtu->nd_opt_mtu_mtu);
if (mtu != nd->mtu) {
nd->mtu = MAX(mtu, IP6_MIN_MTU);
log_ndisc(nd, "Router Advertisement link MTU %d using %d",
mtu, nd->mtu);
}
break;
case ND_OPT_PREFIX_INFORMATION:
opt_prefix = opt;
ndisc_prefix_update(nd, len, opt_prefix);
break;
}
len -= opt_hdr->nd_opt_len * NDISC_OPT_LEN_UNITS;
opt = (void *)((char *)opt +
opt_hdr->nd_opt_len * NDISC_OPT_LEN_UNITS);
opt_hdr = opt;
}
if (len > 0)
log_ndisc(nd, "Router Advertisement contains %zd bytes of trailing garbage", len);
return 0;
}
static int ndisc_router_advertisment_recv(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
_cleanup_free_ struct nd_router_advert *ra = NULL;
sd_ndisc *nd = userdata;
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_LEN(sizeof(int))];
} 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;
struct in6_addr *gw;
unsigned lifetime;
ssize_t len;
int r, pref, stateful, buflen = 0;
assert(s);
assert(nd);
assert(nd->event);
r = ioctl(fd, FIONREAD, &buflen);
if (r < 0)
return -errno;
else if (buflen < 0)
/* This really should not happen */
return -EIO;
iov.iov_len = buflen;
ra = malloc(iov.iov_len);
if (!ra)
return -ENOMEM;
iov.iov_base = ra;
len = recvmsg(fd, &msg, 0);
if (len < 0) {
if (errno == EAGAIN || errno == EINTR)
return 0;
log_ndisc(nd, "Could not receive message from ICMPv6 socket: %m");
return -errno;
} else if ((size_t)len < sizeof(struct nd_router_advert)) {
return 0;
} else if (msg.msg_namelen == 0)
gw = NULL; /* only happens when running the test-suite over a socketpair */
else if (msg.msg_namelen != sizeof(sa.in6)) {
log_ndisc(nd, "Received invalid source address size from ICMPv6 socket: %zu bytes", (size_t)msg.msg_namelen);
return 0;
} else
gw = &sa.in6.sin6_addr;
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(nd, "Received RA with invalid hop limit %d. Ignoring.", hops);
return 0;
}
break;
}
}
if (gw && !in_addr_is_link_local(AF_INET6, (const union in_addr_union*) gw)) {
_cleanup_free_ char *addr = NULL;
(void)in_addr_to_string(AF_INET6, (const union in_addr_union*) gw, &addr);
log_ndisc(nd, "Received RA from non-link-local address %s. Ignoring.", strna(addr));
return 0;
}
if (ra->nd_ra_type != ND_ROUTER_ADVERT)
return 0;
if (ra->nd_ra_code != 0)
return 0;
nd->timeout = sd_event_source_unref(nd->timeout);
nd->state = NDISC_STATE_ADVERTISMENT_LISTEN;
stateful = ra->nd_ra_flags_reserved & (ND_RA_FLAG_MANAGED | ND_RA_FLAG_OTHER);
pref = (ra->nd_ra_flags_reserved & ND_RA_FLAG_PREF) >> 3;
switch (pref) {
case ND_RA_FLAG_PREF_LOW:
case ND_RA_FLAG_PREF_HIGH:
break;
default:
pref = ND_RA_FLAG_PREF_MEDIUM;
break;
}
lifetime = be16toh(ra->nd_ra_router_lifetime);
log_ndisc(nd, "Received Router Advertisement: flags %s preference %s lifetime %u sec",
stateful & ND_RA_FLAG_MANAGED ? "MANAGED" : stateful & ND_RA_FLAG_OTHER ? "OTHER" : "none",
pref == ND_RA_FLAG_PREF_HIGH ? "high" : pref == ND_RA_FLAG_PREF_LOW ? "low" : "medium",
lifetime);
r = ndisc_ra_parse(nd, ra, len);
if (r < 0) {
log_ndisc(nd, "Could not parse Router Advertisement: %s", strerror(-r));
return 0;
}
if (nd->router_callback)
nd->router_callback(nd, stateful, gw, lifetime, pref, nd->userdata);
return 0;
}
static int ndisc_router_solicitation_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
sd_ndisc *nd = userdata;
uint64_t time_now, next_timeout;
int r;
assert(s);
assert(nd);
assert(nd->event);
nd->timeout = sd_event_source_unref(nd->timeout);
if (nd->nd_sent >= NDISC_MAX_ROUTER_SOLICITATIONS) {
if (nd->callback)
nd->callback(nd, SD_NDISC_EVENT_TIMEOUT, nd->userdata);
nd->state = NDISC_STATE_ADVERTISMENT_LISTEN;
} else {
r = icmp6_send_router_solicitation(nd->fd, &nd->mac_addr);
if (r < 0)
log_ndisc(nd, "Error sending Router Solicitation");
else {
nd->state = NDISC_STATE_SOLICITATION_SENT;
log_ndisc(nd, "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_add_time(nd->event, &nd->timeout, clock_boottime_or_monotonic(),
next_timeout, 0,
ndisc_router_solicitation_timeout, nd);
if (r < 0) {
/* we cannot continue if we are unable to rearm the timer */
sd_ndisc_stop(nd);
return 0;
}
r = sd_event_source_set_priority(nd->timeout, nd->event_priority);
if (r < 0)
return 0;
r = sd_event_source_set_description(nd->timeout, "ndisc-timeout");
if (r < 0)
return 0;
}
return 0;
}
int sd_ndisc_stop(sd_ndisc *nd) {
assert_return(nd, -EINVAL);
assert_return(nd->event, -EINVAL);
log_ndisc(client, "Stop NDisc");
ndisc_init(nd);
nd->state = NDISC_STATE_IDLE;
if (nd->callback)
nd->callback(nd, SD_NDISC_EVENT_STOP, nd->userdata);
return 0;
}
int sd_ndisc_router_discovery_start(sd_ndisc *nd) {
int r;
assert(nd);
assert(nd->event);
if (nd->state != NDISC_STATE_IDLE)
return -EBUSY;
if (nd->index < 1)
return -EINVAL;
r = icmp6_bind_router_solicitation(nd->index);
if (r < 0)
return r;
nd->fd = r;
r = sd_event_add_io(nd->event, &nd->recv, nd->fd, EPOLLIN,
ndisc_router_advertisment_recv, nd);
if (r < 0)
goto error;
r = sd_event_source_set_priority(nd->recv, nd->event_priority);
if (r < 0)
goto error;
r = sd_event_source_set_description(nd->recv, "ndisc-receive-message");
if (r < 0)
goto error;
r = sd_event_add_time(nd->event, &nd->timeout, clock_boottime_or_monotonic(),
0, 0, ndisc_router_solicitation_timeout, nd);
if (r < 0)
goto error;
r = sd_event_source_set_priority(nd->timeout, nd->event_priority);
if (r < 0)
goto error;
r = sd_event_source_set_description(nd->timeout, "ndisc-timeout");
error:
if (r < 0)
ndisc_init(nd);
else
log_ndisc(client, "Start Router Solicitation");
return r;
}
Reference in New Issue View Git Blame Copy Permalink