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bird/nest/rt-dev.c
Maria Matejka f0507f05ce Route sources have an explicit owner
This commit prevents use-after-free of routes belonging to protocols
which have been already destroyed, delaying also all the protocols'
shutdown until all of their routes have been finally propagated through
all the pipes down to the appropriate exports.

The use-after-free was somehow hypothetic yet theoretically possible in
rare conditions, when one BGP protocol authors a lot of routes and the
user deletes that protocol by reconfiguring in the same time as next hop
update is requested, causing rte_better() to be called on a
not-yet-pruned network prefix while the owner protocol has been already
freed.

In parallel execution environments, this would happen an inter-thread
use-after-free, causing possible heisenbugs or other nasty problems.
2021-11-22 19:05:44 +01:00

199 lines
4.8 KiB
C

/*
* BIRD -- Direct Device Routes
*
* (c) 1998--2000 Martin Mares <mj@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
/**
* DOC: Direct
*
* The Direct protocol works by converting all ifa_notify() events it receives
* to rte_update() calls for the corresponding network.
*/
#undef LOCAL_DEBUG
#include "nest/bird.h"
#include "nest/iface.h"
#include "nest/protocol.h"
#include "nest/route.h"
#include "nest/rt-dev.h"
#include "conf/conf.h"
#include "lib/resource.h"
#include "lib/string.h"
static void
dev_ifa_notify(struct proto *P, uint flags, struct ifa *ad)
{
struct rt_dev_proto *p = (void *) P;
struct rt_dev_config *cf = (void *) P->cf;
struct channel *c;
net_addr *net = &ad->prefix;
if (!EMPTY_LIST(cf->iface_list) &&
!iface_patt_find(&cf->iface_list, ad->iface, ad))
/* Empty list is automatically treated as "*" */
return;
if (ad->flags & IA_SECONDARY)
return;
if (ad->scope <= SCOPE_LINK)
return;
if (ad->prefix.type == NET_IP4)
c = p->ip4_channel;
else if (ad->prefix.type == NET_IP6)
c = p->ip6_channel;
else
return;
if (!c)
return;
/* For IPv6 SADR, replace regular prefix with SADR prefix */
if (c->net_type == NET_IP6_SADR)
{
net = alloca(sizeof(net_addr_ip6_sadr));
net_fill_ip6_sadr(net, net6_prefix(&ad->prefix), net6_pxlen(&ad->prefix), IP6_NONE, 0);
}
if (flags & IF_CHANGE_DOWN)
{
DBG("dev_if_notify: %s:%I going down\n", ad->iface->name, ad->ip);
/* Use iface ID as local source ID */
struct rte_src *src = rt_get_source(P, ad->iface->index);
rte_update(c, net, NULL, src);
rt_unlock_source(src);
}
else if (flags & IF_CHANGE_UP)
{
DBG("dev_if_notify: %s:%I going up\n", ad->iface->name, ad->ip);
if (cf->check_link && !(ad->iface->flags & IF_LINK_UP))
return;
/* Use iface ID as local source ID */
struct rte_src *src = rt_get_source(P, ad->iface->index);
rta a0 = {
.pref = c->preference,
.source = RTS_DEVICE,
.scope = SCOPE_UNIVERSE,
.dest = RTD_UNICAST,
.nh.iface = ad->iface,
};
rte e0 = {
.attrs = rta_lookup(&a0),
.src = src,
};
rte_update(c, net, &e0, src);
rt_unlock_source(src);
}
}
static void
dev_if_notify(struct proto *p, uint c, struct iface *iface)
{
struct rt_dev_config *cf = (void *) p->cf;
if (c & (IF_CHANGE_UP | IF_CHANGE_DOWN))
return;
if ((c & IF_CHANGE_LINK) && cf->check_link)
{
uint ac = (iface->flags & IF_LINK_UP) ? IF_CHANGE_UP : IF_CHANGE_DOWN;
struct ifa *a;
WALK_LIST(a, iface->addrs)
dev_ifa_notify(p, ac, a);
}
}
static void
dev_postconfig(struct proto_config *CF)
{
struct rt_dev_config *cf = (void *) CF;
struct channel_config *ip4, *ip6, *ip6_sadr;
ip4 = proto_cf_find_channel(CF, NET_IP4);
ip6 = proto_cf_find_channel(CF, NET_IP6);
ip6_sadr = proto_cf_find_channel(CF, NET_IP6_SADR);
if (ip6 && ip6_sadr)
cf_error("Both ipv6 and ipv6-sadr channels");
cf->ip4_channel = ip4;
cf->ip6_channel = ip6 ?: ip6_sadr;
}
static struct proto *
dev_init(struct proto_config *CF)
{
struct proto *P = proto_new(CF);
struct rt_dev_proto *p = (void *) P;
struct rt_dev_config *cf = (void *) CF;
proto_configure_channel(P, &p->ip4_channel, cf->ip4_channel);
proto_configure_channel(P, &p->ip6_channel, cf->ip6_channel);
P->if_notify = dev_if_notify;
P->ifa_notify = dev_ifa_notify;
return P;
}
static int
dev_reconfigure(struct proto *P, struct proto_config *CF)
{
struct rt_dev_proto *p = (void *) P;
struct rt_dev_config *o = (void *) P->cf;
struct rt_dev_config *n = (void *) CF;
if (!iface_patts_equal(&o->iface_list, &n->iface_list, NULL) ||
(o->check_link != n->check_link))
return 0;
return
proto_configure_channel(P, &p->ip4_channel, n->ip4_channel) &&
proto_configure_channel(P, &p->ip6_channel, n->ip6_channel);
return 1;
}
static void
dev_copy_config(struct proto_config *dest, struct proto_config *src)
{
struct rt_dev_config *d = (void *) dest;
struct rt_dev_config *s = (void *) src;
/*
* We copy iface_list as ifaces can be shared by more direct protocols.
* Copy suffices to be is shallow, because new nodes can be added, but
* old nodes cannot be modified (although they contain internal lists).
*/
cfg_copy_list(&d->iface_list, &s->iface_list, sizeof(struct iface_patt));
d->check_link = s->check_link;
}
struct protocol proto_device = {
.name = "Direct",
.template = "direct%d",
.class = PROTOCOL_DIRECT,
.preference = DEF_PREF_DIRECT,
.channel_mask = NB_IP | NB_IP6_SADR,
.proto_size = sizeof(struct rt_dev_proto),
.config_size = sizeof(struct rt_dev_config),
.postconfig = dev_postconfig,
.init = dev_init,
.reconfigure = dev_reconfigure,
.copy_config = dev_copy_config
};