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56cd007ab8
systemd/src/libsystemd-network/sd-ipv4ll.c
Patrik Flykt 56cd007ab8 sd-ipv4ll: Add reference counting for IPv4LL 
Similar to DHCP, the IPv4LL library user can decide to free the LL
client any time the callback is called. Guard against freeing the
LL client in the callback by introducing proper reference counting.

Also update code using the IPv4LL library to properly handle a
returned NULL from the notify and stop functions if the IPv4LL
client was freed.
2014-04-11 10:53:52 +03:00

628 lines
18 KiB
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/***
This file is part of systemd.
Copyright (C) 2014 Axis Communications AB. 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 <stdlib.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <arpa/inet.h>
#include "util.h"
#include "siphash24.h"
#include "list.h"
#include "refcnt.h"
#include "ipv4ll-internal.h"
#include "sd-ipv4ll.h"
/* Constants from the RFC */
#define PROBE_WAIT 1
#define PROBE_NUM 3
#define PROBE_MIN 1
#define PROBE_MAX 2
#define ANNOUNCE_WAIT 2
#define ANNOUNCE_NUM 2
#define ANNOUNCE_INTERVAL 2
#define MAX_CONFLICTS 10
#define RATE_LIMIT_INTERVAL 60
#define DEFEND_INTERVAL 10
#define IPV4LL_NETWORK 0xA9FE0000L
#define IPV4LL_NETMASK 0xFFFF0000L
typedef enum IPv4LLTrigger{
IPV4LL_TRIGGER_NULL,
IPV4LL_TRIGGER_PACKET,
IPV4LL_TRIGGER_TIMEOUT,
_IPV4LL_TRIGGER_MAX,
_IPV4LL_TRIGGER_INVALID = -1
} IPv4LLTrigger;
typedef enum IPv4LLState {
IPV4LL_STATE_INIT,
IPV4LL_STATE_WAITING_PROBE,
IPV4LL_STATE_PROBING,
IPV4LL_STATE_WAITING_ANNOUNCE,
IPV4LL_STATE_ANNOUNCING,
IPV4LL_STATE_RUNNING,
_IPV4LL_STATE_MAX,
_IPV4LL_STATE_INVALID = -1
} IPv4LLState;
struct sd_ipv4ll {
RefCount n_ref;
IPv4LLState state;
int index;
int fd;
union sockaddr_union link;
int iteration;
int conflict;
sd_event_source *receive_message;
sd_event_source *timer;
usec_t next_wakeup;
usec_t defend_window;
int next_wakeup_valid;
be32_t address;
struct random_data *random_data;
char *random_data_state;
/* External */
be32_t claimed_address;
struct ether_addr mac_addr;
sd_event *event;
int event_priority;
sd_ipv4ll_cb_t cb;
void* userdata;
};
static void ipv4ll_run_state_machine(sd_ipv4ll *ll, IPv4LLTrigger trigger, void *trigger_data);
static void ipv4ll_set_state(sd_ipv4ll *ll, IPv4LLState st, int reset_counter) {
assert(ll);
assert(st < _IPV4LL_STATE_MAX);
if (st == ll->state && !reset_counter) {
ll->iteration++;
} else {
ll->state = st;
ll->iteration = 0;
}
}
static sd_ipv4ll *ipv4ll_client_notify(sd_ipv4ll *ll, int event) {
assert(ll);
if (ll->cb) {
ll = sd_ipv4ll_ref(ll);
ll->cb(ll, event, ll->userdata);
ll = sd_ipv4ll_unref(ll);
}
return ll;
}
static sd_ipv4ll *ipv4ll_stop(sd_ipv4ll *ll, int event) {
assert(ll);
ll->receive_message = sd_event_source_unref(ll->receive_message);
ll->fd = safe_close(ll->fd);
ll->timer = sd_event_source_unref(ll->timer);
log_ipv4ll(ll, "STOPPED");
ll = ipv4ll_client_notify(ll, event);
if (ll) {
ll->claimed_address = 0;
ipv4ll_set_state (ll, IPV4LL_STATE_INIT, 1);
}
return ll;
}
static int ipv4ll_pick_address(sd_ipv4ll *ll, be32_t *address) {
be32_t addr;
int r;
int32_t random;
assert(ll);
assert(address);
assert(ll->random_data);
do {
r = random_r(ll->random_data, &random);
if (r < 0)
return r;
addr = htonl((random & 0x0000FFFF) | IPV4LL_NETWORK);
} while (addr == ll->address ||
(ntohl(addr) & IPV4LL_NETMASK) != IPV4LL_NETWORK ||
(ntohl(addr) & 0x0000FF00) == 0x0000 ||
(ntohl(addr) & 0x0000FF00) == 0xFF00);
*address = addr;
return 0;
}
static int ipv4ll_timer(sd_event_source *s, uint64_t usec, void *userdata) {
sd_ipv4ll *ll = (sd_ipv4ll*)userdata;
assert(ll);
ll->next_wakeup_valid = 0;
ipv4ll_run_state_machine(ll, IPV4LL_TRIGGER_TIMEOUT, NULL);
return 0;
}
static void ipv4ll_set_next_wakeup(sd_ipv4ll *ll, int sec, int random_sec) {
usec_t next_timeout = 0;
usec_t time_now = 0;
assert(sec >= 0);
assert(random_sec >= 0);
assert(ll);
next_timeout = sec * USEC_PER_SEC;
if (random_sec)
next_timeout += random_u32() % (random_sec * USEC_PER_SEC);
if (sd_event_now(ll->event, CLOCK_MONOTONIC, &time_now) < 0)
time_now = now(CLOCK_MONOTONIC);
ll->next_wakeup = time_now + next_timeout;
ll->next_wakeup_valid = 1;
}
static bool ipv4ll_arp_conflict (sd_ipv4ll *ll, struct ether_arp *arp) {
assert(ll);
assert(arp);
if (memcmp(arp->arp_spa, &ll->address, sizeof(ll->address)) == 0 &&
memcmp(arp->arp_sha, &ll->mac_addr, ETH_ALEN) != 0)
return true;
return false;
}
static bool ipv4ll_arp_probe_conflict (sd_ipv4ll *ll, struct ether_arp *arp) {
assert(ll);
assert(arp);
if (ipv4ll_arp_conflict(ll, arp))
return true;
if (memcmp(arp->arp_tpa, &ll->address, sizeof(ll->address)) == 0 &&
memcmp(arp->arp_sha, &ll->mac_addr, ETH_ALEN))
return true;
return false;
}
static void ipv4ll_run_state_machine(sd_ipv4ll *ll, IPv4LLTrigger trigger, void *trigger_data) {
struct ether_arp out_packet;
int out_packet_ready = 0;
int r = 0;
assert(ll);
assert(trigger < _IPV4LL_TRIGGER_MAX);
if (ll->state == IPV4LL_STATE_INIT) {
log_ipv4ll(ll, "PROBE");
ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_PROBE, 1);
ipv4ll_set_next_wakeup(ll, 0, PROBE_WAIT);
} else if ((ll->state == IPV4LL_STATE_WAITING_PROBE && trigger == IPV4LL_TRIGGER_TIMEOUT) ||
(ll->state == IPV4LL_STATE_PROBING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration < PROBE_NUM-2)) {
/* Send a probe */
arp_packet_probe(&out_packet, ll->address, &ll->mac_addr);
out_packet_ready = 1;
ipv4ll_set_state(ll, IPV4LL_STATE_PROBING, 0);
ipv4ll_set_next_wakeup(ll, PROBE_MIN, (PROBE_MAX-PROBE_MIN));
} else if (ll->state == IPV4LL_STATE_PROBING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration >= PROBE_NUM-2) {
/* Send the last probe */
arp_packet_probe(&out_packet, ll->address, &ll->mac_addr);
out_packet_ready = 1;
ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_ANNOUNCE, 1);
ipv4ll_set_next_wakeup(ll, ANNOUNCE_WAIT, 0);
} else if ((ll->state == IPV4LL_STATE_WAITING_ANNOUNCE && trigger == IPV4LL_TRIGGER_TIMEOUT) ||
(ll->state == IPV4LL_STATE_ANNOUNCING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration < ANNOUNCE_NUM-1)) {
/* Send announcement packet */
arp_packet_announcement(&out_packet, ll->address, &ll->mac_addr);
out_packet_ready = 1;
ipv4ll_set_state(ll, IPV4LL_STATE_ANNOUNCING, 0);
ipv4ll_set_next_wakeup(ll, ANNOUNCE_INTERVAL, 0);
if (ll->iteration == 0) {
log_ipv4ll(ll, "ANNOUNCE");
ll->claimed_address = ll->address;
ll = ipv4ll_client_notify(ll, IPV4LL_EVENT_BIND);
if (!ll)
goto out;
ll->conflict = 0;
}
} else if ((ll->state == IPV4LL_STATE_ANNOUNCING && trigger == IPV4LL_TRIGGER_TIMEOUT &&
ll->iteration >= ANNOUNCE_NUM-1)) {
ipv4ll_set_state(ll, IPV4LL_STATE_RUNNING, 0);
ll->next_wakeup_valid = 0;
} else if (trigger == IPV4LL_TRIGGER_PACKET) {
int conflicted = 0;
usec_t time_now;
struct ether_arp* in_packet = (struct ether_arp*)trigger_data;
assert(in_packet);
if (IN_SET(ll->state, IPV4LL_STATE_ANNOUNCING, IPV4LL_STATE_RUNNING)) {
if (ipv4ll_arp_conflict(ll, in_packet)) {
r = sd_event_now(ll->event, CLOCK_MONOTONIC, &time_now);
if (r < 0)
goto out;
/* Defend address */
if (time_now > ll->defend_window) {
ll->defend_window = time_now + DEFEND_INTERVAL * USEC_PER_SEC;
arp_packet_announcement(&out_packet, ll->address, &ll->mac_addr);
out_packet_ready = 1;
} else
conflicted = 1;
}
} else if (IN_SET(ll->state, IPV4LL_STATE_WAITING_PROBE,
IPV4LL_STATE_PROBING,
IPV4LL_STATE_WAITING_ANNOUNCE)) {
conflicted = ipv4ll_arp_probe_conflict(ll, in_packet);
}
if (conflicted) {
log_ipv4ll(ll, "CONFLICT");
ll = ipv4ll_client_notify(ll, IPV4LL_EVENT_CONFLICT);
if (!ll)
goto out;
ll->claimed_address = 0;
/* Pick a new address */
r = ipv4ll_pick_address(ll, &ll->address);
if (r < 0)
goto out;
ll->conflict++;
ll->defend_window = 0;
ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_PROBE, 1);
if (ll->conflict >= MAX_CONFLICTS) {
log_ipv4ll(ll, "MAX_CONFLICTS");
ipv4ll_set_next_wakeup(ll, RATE_LIMIT_INTERVAL, PROBE_WAIT);
} else
ipv4ll_set_next_wakeup(ll, 0, PROBE_WAIT);
}
}
if (out_packet_ready) {
r = arp_network_send_raw_socket(ll->fd, &ll->link, &out_packet);
if (r < 0) {
log_ipv4ll(ll, "failed to send arp packet out");
goto out;
}
}
if (ll->next_wakeup_valid) {
ll->timer = sd_event_source_unref(ll->timer);
r = sd_event_add_time(ll->event, &ll->timer, CLOCK_MONOTONIC,
ll->next_wakeup, 0, ipv4ll_timer, ll);
if (r < 0)
goto out;
r = sd_event_source_set_priority(ll->timer, ll->event_priority);
if (r < 0)
goto out;
}
out:
if (r < 0 && ll)
ipv4ll_stop(ll, r);
}
static int ipv4ll_receive_message(sd_event_source *s, int fd,
uint32_t revents, void *userdata) {
int r;
struct ether_arp arp;
sd_ipv4ll *ll = (sd_ipv4ll*)userdata;
assert(ll);
r = read(fd, &arp, sizeof(struct ether_arp));
if (r < (int) sizeof(struct ether_arp))
return 0;
r = arp_packet_verify_headers(&arp);
if (r < 0)
return 0;
ipv4ll_run_state_machine(ll, IPV4LL_TRIGGER_PACKET, &arp);
return 0;
}
int sd_ipv4ll_set_index(sd_ipv4ll *ll, int interface_index) {
assert_return(ll, -EINVAL);
assert_return(interface_index >= -1, -EINVAL);
assert_return(ll->state == IPV4LL_STATE_INIT, -EBUSY);
ll->index = interface_index;
return 0;
}
int sd_ipv4ll_set_mac(sd_ipv4ll *ll, const struct ether_addr *addr) {
bool need_restart = false;
assert_return(ll, -EINVAL);
assert_return(addr, -EINVAL);
if (memcmp(&ll->mac_addr, addr, ETH_ALEN) == 0)
return 0;
if (ll->state != IPV4LL_STATE_INIT) {
log_ipv4ll(ll, "Changing MAC address on running IPv4LL "
"client, restarting");
ll = ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
need_restart = true;
}
if (!ll)
return 0;
memcpy(&ll->mac_addr, addr, ETH_ALEN);
if (need_restart)
sd_ipv4ll_start(ll);
return 0;
}
int sd_ipv4ll_detach_event(sd_ipv4ll *ll) {
assert_return(ll, -EINVAL);
ll->event = sd_event_unref(ll->event);
return 0;
}
int sd_ipv4ll_attach_event(sd_ipv4ll *ll, sd_event *event, int priority) {
int r;
assert_return(ll, -EINVAL);
assert_return(!ll->event, -EBUSY);
if (event)
ll->event = sd_event_ref(event);
else {
r = sd_event_default(&ll->event);
if (r < 0) {
ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
return r;
}
}
ll->event_priority = priority;
return 0;
}
int sd_ipv4ll_set_callback(sd_ipv4ll *ll, sd_ipv4ll_cb_t cb, void *userdata) {
assert_return(ll, -EINVAL);
ll->cb = cb;
ll->userdata = userdata;
return 0;
}
int sd_ipv4ll_get_address(sd_ipv4ll *ll, struct in_addr *address){
assert_return(ll, -EINVAL);
assert_return(address, -EINVAL);
if (ll->claimed_address == 0) {
return -ENOENT;
}
address->s_addr = ll->claimed_address;
return 0;
}
int sd_ipv4ll_set_address_seed (sd_ipv4ll *ll, uint8_t seed[8]) {
unsigned int entropy = *seed;
int r;
assert_return(ll, -EINVAL);
free(ll->random_data);
free(ll->random_data_state);
ll->random_data = new0(struct random_data, 1);
ll->random_data_state = new0(char, 128);
if (!ll->random_data || !ll->random_data_state) {
r = -ENOMEM;
goto error;
}
r = initstate_r((unsigned int)entropy, ll->random_data_state, 128, ll->random_data);
if (r < 0)
goto error;
error:
if (r < 0){
free(ll->random_data);
free(ll->random_data_state);
ll->random_data = NULL;
ll->random_data_state = NULL;
}
return r;
}
bool sd_ipv4ll_is_running(sd_ipv4ll *ll) {
assert_return(ll, -EINVAL);
return ll->state != IPV4LL_STATE_INIT;
}
#define HASH_KEY SD_ID128_MAKE(df,04,22,98,3f,ad,14,52,f9,87,2e,d1,9c,70,e2,f2)
int sd_ipv4ll_start (sd_ipv4ll *ll) {
int r;
assert_return(ll, -EINVAL);
assert_return(ll->event, -EINVAL);
assert_return(ll->index > 0, -EINVAL);
assert_return(ll->state == IPV4LL_STATE_INIT, -EBUSY);
r = arp_network_bind_raw_socket(ll->index, &ll->link);
if (r < 0)
goto out;
ll->fd = r;
ll->conflict = 0;
ll->defend_window = 0;
ll->claimed_address = 0;
if (!ll->random_data) {
uint8_t seed[8];
/* Fallback to mac */
siphash24(seed, &ll->mac_addr.ether_addr_octet,
ETH_ALEN, HASH_KEY.bytes);
r = sd_ipv4ll_set_address_seed(ll, seed);
if (r < 0)
goto out;
}
if (ll->address == 0) {
r = ipv4ll_pick_address(ll, &ll->address);
if (r < 0)
goto out;
}
ipv4ll_set_state (ll, IPV4LL_STATE_INIT, 1);
r = sd_event_add_io(ll->event, &ll->receive_message, ll->fd,
EPOLLIN, ipv4ll_receive_message, ll);
if (r < 0)
goto out;
r = sd_event_source_set_priority(ll->receive_message, ll->event_priority);
if (r < 0)
goto out;
r = sd_event_add_time(ll->event,
&ll->timer,
CLOCK_MONOTONIC,
now(CLOCK_MONOTONIC), 0,
ipv4ll_timer, ll);
if (r < 0)
goto out;
r = sd_event_source_set_priority(ll->timer, ll->event_priority);
out:
if (r < 0)
ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
return 0;
}
int sd_ipv4ll_stop(sd_ipv4ll *ll) {
ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
return 0;
}
sd_ipv4ll *sd_ipv4ll_ref(sd_ipv4ll *ll) {
if (ll)
assert_se(REFCNT_INC(ll->n_ref) >= 2);
return ll;
}
sd_ipv4ll *sd_ipv4ll_unref(sd_ipv4ll *ll) {
if (ll && REFCNT_DEC(ll->n_ref) <= 0) {
ll->receive_message =
sd_event_source_unref(ll->receive_message);
ll->fd = safe_close(ll->fd);
ll->timer = sd_event_source_unref(ll->timer);
sd_ipv4ll_detach_event(ll);
free(ll->random_data);
free(ll->random_data_state);
free(ll);
return NULL;
}
return ll;
}
DEFINE_TRIVIAL_CLEANUP_FUNC(sd_ipv4ll*, sd_ipv4ll_unref);
#define _cleanup_ipv4ll_free_ _cleanup_(sd_ipv4ll_unrefp)
int sd_ipv4ll_new(sd_ipv4ll **ret) {
_cleanup_ipv4ll_free_ sd_ipv4ll *ll = NULL;
assert_return(ret, -EINVAL);
ll = new0(sd_ipv4ll, 1);
if (!ll)
return -ENOMEM;
ll->n_ref = REFCNT_INIT;
ll->state = IPV4LL_STATE_INIT;
ll->index = -1;
ll->fd = -1;
*ret = ll;
ll = NULL;
return 0;
}
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