bird/sysdep/bsd/krt-sock.c
Ondrej Zajicek c429d4a4ba Restrict export of device routes to the kernel protocol.
In usual configuration, such export is already restricted
with the aid of the direct protocol but there are some
races that can circumvent it. This makes it harder to
break kernel device routes. Also adds an option to
disable this restriction.
2010-04-04 15:41:31 +02:00

699 lines
14 KiB
C

/*
* BIRD -- Unix Routing Table Syncing
*
* (c) 2004 Ondrej Filip <feela@network.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#include <stdio.h>
#include <ctype.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <net/route.h>
#include <net/if.h>
#include <net/if_dl.h>
#undef LOCAL_DEBUG
#include "nest/bird.h"
#include "nest/iface.h"
#include "nest/route.h"
#include "nest/protocol.h"
#include "nest/iface.h"
#include "lib/timer.h"
#include "lib/unix.h"
#include "lib/krt.h"
#include "lib/string.h"
#include "lib/socket.h"
int rt_sock = 0;
int
krt_capable(rte *e)
{
rta *a = e->attrs;
return
a->cast == RTC_UNICAST &&
(a->dest == RTD_ROUTER
|| a->dest == RTD_DEVICE
#ifdef RTF_REJECT
|| a->dest == RTD_UNREACHABLE
#endif
#ifdef RTF_BLACKHOLE
|| a->dest == RTD_BLACKHOLE
#endif
);
}
#define ROUNDUP(a) \
((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
#define NEXTADDR(w, u) \
if (msg.rtm.rtm_addrs & (w)) {\
l = ROUNDUP(((struct sockaddr *)&(u))->sa_len);\
memmove(body, &(u), l); body += l;}
#define GETADDR(p, F) \
bzero(p, sizeof(*p));\
if ((addrs & (F)) && ((struct sockaddr *)body)->sa_len) {\
unsigned int l = ROUNDUP(((struct sockaddr *)body)->sa_len);\
memcpy(p, body, (l > sizeof(*p) ? sizeof(*p) : l));\
body += l;}
static void
krt_sock_send(int cmd, rte *e)
{
net *net = e->net;
rta *a = e->attrs;
static int msg_seq;
struct iface *j, *i = a->iface;
int l;
struct ks_msg msg;
char *body = (char *)msg.buf;
sockaddr gate, mask, dst;
ip_addr gw;
DBG("krt-sock: send %I/%d via %I\n", net->n.prefix, net->n.pxlen, a->gw);
bzero(&msg,sizeof (struct rt_msghdr));
msg.rtm.rtm_version = RTM_VERSION;
msg.rtm.rtm_type = cmd;
msg.rtm.rtm_seq = msg_seq++;
msg.rtm.rtm_addrs = RTA_DST;
msg.rtm.rtm_flags = RTF_UP | RTF_PROTO1;
if (net->n.pxlen == MAX_PREFIX_LENGTH)
{
msg.rtm.rtm_flags |= RTF_HOST;
}
else
{
msg.rtm.rtm_addrs |= RTA_NETMASK;
}
#ifdef RTF_REJECT
if(a->dest == RTD_UNREACHABLE)
msg.rtm.rtm_flags |= RTF_REJECT;
#endif
#ifdef RTF_BLACKHOLE
if(a->dest == RTD_BLACKHOLE)
msg.rtm.rtm_flags |= RTF_BLACKHOLE;
#endif
/* This is really very nasty, but I'm not able
* to add "(reject|blackhole)" route without
* gateway set
*/
if(!i)
{
i = HEAD(iface_list);
WALK_LIST(j, iface_list)
{
if (j->flags & IF_LOOPBACK)
{
i = j;
break;
}
}
}
gw = a->gw;
#ifdef IPV6
/* Embed interface ID to link-local address */
if (ipa_has_link_scope(gw))
_I0(gw) = 0xfe800000 | (i->index & 0x0000ffff);
#endif
fill_in_sockaddr(&dst, net->n.prefix, 0);
fill_in_sockaddr(&mask, ipa_mkmask(net->n.pxlen), 0);
fill_in_sockaddr(&gate, gw, 0);
switch (a->dest)
{
case RTD_ROUTER:
msg.rtm.rtm_flags |= RTF_GATEWAY;
msg.rtm.rtm_addrs |= RTA_GATEWAY;
break;
#ifdef RTF_REJECT
case RTD_UNREACHABLE:
#endif
#ifdef RTF_BLACKHOLE
case RTD_BLACKHOLE:
#endif
case RTD_DEVICE:
if(i)
{
#ifdef RTF_CLONING
if (cmd == RTM_ADD && (i->flags & IF_MULTIACCESS) != IF_MULTIACCESS) /* PTP */
msg.rtm.rtm_flags |= RTF_CLONING;
#endif
if(!i->addr) {
log(L_ERR "KRT: interface %s has no IP addess", i->name);
return;
}
fill_in_sockaddr(&gate, i->addr->ip, 0);
msg.rtm.rtm_addrs |= RTA_GATEWAY;
}
break;
default:
bug("krt-sock: unknown flags, but not filtered");
}
msg.rtm.rtm_index = i->index;
NEXTADDR(RTA_DST, dst);
NEXTADDR(RTA_GATEWAY, gate);
NEXTADDR(RTA_NETMASK, mask);
l = body - (char *)&msg;
msg.rtm.rtm_msglen = l;
if ((l = write(rt_sock, (char *)&msg, l)) < 0) {
log(L_ERR "KRT: Error sending route %I/%d to kernel", net->n.prefix, net->n.pxlen);
}
}
void
krt_set_notify(struct krt_proto *p UNUSED, net *net, rte *new, rte *old)
{
if (old)
{
DBG("krt_remove_route(%I/%d)\n", net->n.prefix, net->n.pxlen);
krt_sock_send(RTM_DELETE, old);
}
if (new)
{
DBG("krt_add_route(%I/%d)\n", net->n.prefix, net->n.pxlen);
krt_sock_send(RTM_ADD, new);
}
}
static int
krt_set_hook(sock *sk, int size UNUSED)
{
struct ks_msg msg;
int l = read(sk->fd, (char *)&msg, sizeof(msg));
if(l <= 0)
log(L_ERR "krt-sock: read failed");
else
krt_read_msg((struct proto *)sk->data, &msg, 0);
return 0;
}
void
krt_set_start(struct krt_proto *x, int first UNUSED)
{
sock *sk_rt;
static int ks_open_tried = 0;
if (ks_open_tried)
return;
ks_open_tried = 1;
DBG("KRT: Opening kernel socket\n");
if( (rt_sock = socket(PF_ROUTE, SOCK_RAW, AF_UNSPEC)) < 0)
die("Cannot open kernel socket for routes");
sk_rt = sk_new(krt_pool);
sk_rt->type = SK_MAGIC;
sk_rt->rx_hook = krt_set_hook;
sk_rt->fd = rt_sock;
sk_rt->data = x;
if (sk_open(sk_rt))
bug("krt-sock: sk_open failed");
}
#define SKIP(ARG...) do { DBG("KRT: Ignoring route - " ARG); return; } while(0)
static void
krt_read_rt(struct ks_msg *msg, struct krt_proto *p, int scan)
{
rta a;
rte *e;
net *net;
sockaddr dst, gate, mask;
ip_addr idst, igate, imask;
void *body = (char *)msg->buf;
int new = (msg->rtm.rtm_type == RTM_ADD);
int src;
char *errmsg = "KRT: Invalid route received";
int flags = msg->rtm.rtm_flags;
int addrs = msg->rtm.rtm_addrs;
if (!(flags & RTF_UP) && scan)
SKIP("not up in scan\n");
if (!(flags & RTF_DONE) && !scan)
SKIP("not done in async\n");
if (flags & RTF_LLINFO)
SKIP("link-local\n");
GETADDR(&dst, RTA_DST);
GETADDR(&gate, RTA_GATEWAY);
GETADDR(&mask, RTA_NETMASK);
if (sa_family_check(&dst))
get_sockaddr(&dst, &idst, NULL, 0);
else
SKIP("invalid DST");
/* We will check later whether we have valid gateway addr */
if (sa_family_check(&gate))
get_sockaddr(&gate, &igate, NULL, 0);
else
igate = IPA_NONE;
/* We do not test family for RTA_NETMASK, because BSD sends us
some strange values, but interpreting them as IPv4/IPv6 works */
get_sockaddr(&mask, &imask, NULL, 0);
int c = ipa_classify_net(idst);
if ((c < 0) || !(c & IADDR_HOST) || ((c & IADDR_SCOPE_MASK) <= SCOPE_LINK))
SKIP("strange class/scope\n");
int pxlen = (flags & RTF_HOST) ? MAX_PREFIX_LENGTH : ipa_mklen(imask);
if (pxlen < 0)
{ log(L_ERR "%s (%I) - netmask %I", errmsg, idst, imask); return; }
if ((flags & RTF_GATEWAY) && ipa_zero(igate))
{ log(L_ERR "%s (%I/%d) - missing gateway", errmsg, idst, pxlen); return; }
u32 self_mask = RTF_PROTO1;
u32 alien_mask = RTF_STATIC | RTF_PROTO1;
#ifdef RTF_PROTO2
alien_mask |= RTF_PROTO2;
#endif
#ifdef RTF_PROTO3
alien_mask |= RTF_PROTO3;
#endif
if (flags & (RTF_DYNAMIC | RTF_MODIFIED))
src = KRT_SRC_REDIRECT;
else if (flags & self_mask)
{
if (!scan)
SKIP("echo\n");
src = KRT_SRC_BIRD;
}
else if (flags & alien_mask)
src = KRT_SRC_ALIEN;
else
src = KRT_SRC_KERNEL;
net = net_get(p->p.table, idst, pxlen);
bzero(&a, sizeof(a));
a.proto = &p->p;
a.source = RTS_INHERIT;
a.scope = SCOPE_UNIVERSE;
a.cast = RTC_UNICAST;
a.flags = a.aflags = 0;
a.from = IPA_NONE;
a.gw = IPA_NONE;
a.iface = NULL;
a.eattrs = NULL;
/* reject/blackhole routes have also set RTF_GATEWAY,
we wil check them first. */
#ifdef RTF_REJECT
if(flags & RTF_REJECT) {
a.dest = RTD_UNREACHABLE;
goto done;
}
#endif
#ifdef RTF_BLACKHOLE
if(flags & RTF_BLACKHOLE) {
a.dest = RTD_BLACKHOLE;
goto done;
}
#endif
a.iface = if_find_by_index(msg->rtm.rtm_index);
if (!a.iface)
{
log(L_ERR "KRT: Received route %I/%d with unknown ifindex %u",
net->n.prefix, net->n.pxlen, msg->rtm.rtm_index);
return;
}
if (flags & RTF_GATEWAY)
{
neighbor *ng;
a.dest = RTD_ROUTER;
a.gw = igate;
#ifdef IPV6
/* Clean up embedded interface ID returned in link-local address */
if (ipa_has_link_scope(a.gw))
_I0(a.gw) = 0xfe800000;
#endif
ng = neigh_find2(&p->p, &a.gw, a.iface, 0);
if (!ng || (ng->scope == SCOPE_HOST))
{
log(L_ERR "KRT: Received route %I/%d with strange next-hop %I",
net->n.prefix, net->n.pxlen, a.gw);
return;
}
}
else
a.dest = RTD_DEVICE;
done:
e = rte_get_temp(&a);
e->net = net;
e->u.krt.src = src;
/* These are probably too Linux-specific */
e->u.krt.proto = 0;
e->u.krt.type = 0;
e->u.krt.metric = 0;
if (scan)
krt_got_route(p, e);
else
krt_got_route_async(p, e, new);
}
static void
krt_read_ifinfo(struct ks_msg *msg)
{
struct if_msghdr *ifm = (struct if_msghdr *)&msg->rtm;
void *body = (void *)(ifm + 1);
struct sockaddr_dl *dl = NULL;
unsigned int i;
struct iface *iface = NULL, f;
char *ifname = "(none)";
int fl = ifm->ifm_flags;
for(i = 1; i!=0; i <<= 1)
{
if((i & ifm->ifm_addrs) && (i == RTA_IFP))
{
if( i == RTA_IFP)
{
dl = (struct sockaddr_dl *)body;
break;
}
body += ROUNDUP(((struct sockaddr *)&(body))->sa_len);\
}
}
if(dl && (dl->sdl_family != AF_LINK))
{
log("Ignoring strange IFINFO");
return;
}
if(dl) ifname = dl->sdl_data;
iface = if_find_by_index(ifm->ifm_index);
if(!iface)
{
/* New interface */
if(!dl) return; /* No interface name, ignoring */
DBG("New interface \"%s\" found", ifname);
bzero(&f, sizeof(f));
f.index = ifm->ifm_index;
strncpy(f.name, ifname, sizeof(f.name) -1);
}
else
{
memcpy(&f, iface, sizeof(struct iface));
}
f.mtu = ifm->ifm_data.ifi_mtu;
f.flags = 0;
if (fl & IFF_UP)
f.flags |= IF_LINK_UP;
if (fl & IFF_LOOPBACK) /* Loopback */
f.flags |= IF_MULTIACCESS | IF_LOOPBACK | IF_IGNORE;
else if (fl & IFF_POINTOPOINT) /* PtP */
f.flags |= IF_MULTICAST;
else if (fl & IFF_BROADCAST) /* Broadcast */
f.flags |= IF_MULTIACCESS | IF_BROADCAST | IF_MULTICAST;
else
f.flags |= IF_MULTIACCESS; /* NBMA */
if((!iface) || memcmp(&f, iface, sizeof(struct iface)))
if_update(&f); /* Just if something happens */
}
static void
krt_read_addr(struct ks_msg *msg)
{
struct ifa_msghdr *ifam = (struct ifa_msghdr *)&msg->rtm;
void *body = (void *)(ifam + 1);
sockaddr addr, mask, brd;
struct iface *iface = NULL;
struct ifa ifa;
struct sockaddr null;
ip_addr iaddr, imask, ibrd;
int addrs = ifam->ifam_addrs;
int scope, masklen = -1;
int new = (ifam->ifam_type == RTM_NEWADDR);
/* Strange messages with zero (invalid) ifindex appear on OpenBSD */
if (ifam->ifam_index == 0)
return;
if(!(iface = if_find_by_index(ifam->ifam_index)))
{
log(L_ERR "KIF: Received address message for unknown interface %d", ifam->ifam_index);
return;
}
GETADDR (&null, RTA_DST);
GETADDR (&null, RTA_GATEWAY);
GETADDR (&mask, RTA_NETMASK);
GETADDR (&null, RTA_GENMASK);
GETADDR (&null, RTA_IFP);
GETADDR (&addr, RTA_IFA);
GETADDR (&null, RTA_AUTHOR);
GETADDR (&brd, RTA_BRD);
/* Some other family address */
if (!sa_family_check(&addr))
return;
get_sockaddr(&addr, &iaddr, NULL, 0);
get_sockaddr(&mask, &imask, NULL, 0);
get_sockaddr(&brd, &ibrd, NULL, 0);
if ((masklen = ipa_mklen(imask)) < 0)
{
log("Invalid masklen");
return;
}
bzero(&ifa, sizeof(ifa));
ifa.iface = iface;
memcpy(&ifa.ip, &iaddr, sizeof(ip_addr));
ifa.pxlen = masklen;
memcpy(&ifa.brd, &ibrd, sizeof(ip_addr));
scope = ipa_classify(ifa.ip);
if (scope < 0)
{
log(L_ERR "KIF: Invalid interface address %I for %s", ifa.ip, iface->name);
return;
}
ifa.scope = scope & IADDR_SCOPE_MASK;
#ifdef IPV6
/* Clean up embedded interface ID returned in link-local address */
if (ipa_has_link_scope(ifa.ip))
_I0(ifa.ip) = 0xfe800000;
#endif
if (iface->flags & IF_MULTIACCESS)
ifa.prefix = ipa_and(ifa.ip, ipa_mkmask(masklen));
else /* PtP iface */
{
ifa.flags |= IA_UNNUMBERED;
ifa.prefix = ifa.opposite = ifa.brd;
}
if (new)
ifa_update(&ifa);
else
ifa_delete(&ifa);
}
void
krt_read_msg(struct proto *p, struct ks_msg *msg, int scan)
{
switch (msg->rtm.rtm_type)
{
case RTM_GET:
if(!scan) return;
case RTM_ADD:
case RTM_DELETE:
krt_read_rt(msg, (struct krt_proto *)p, scan);
break;
case RTM_IFINFO:
krt_read_ifinfo(msg);
break;
case RTM_NEWADDR:
case RTM_DELADDR:
krt_read_addr(msg);
break;
default:
break;
}
}
void
krt_scan_construct(struct krt_config *c UNUSED)
{
}
void
krt_scan_preconfig(struct config *c UNUSED)
{
}
void
krt_scan_postconfig(struct krt_config *c UNUSED)
{
}
void
krt_scan_start(struct krt_proto *x, int first UNUSED)
{
init_list(&x->scan.temp_ifs);
}
void
krt_scan_shutdown(struct krt_proto *x UNUSED, int last UNUSED)
{
}
static void
krt_sysctl_scan(struct proto *p, pool *pool, byte **buf, size_t *bl, int cmd)
{
byte *next;
int mib[6], on;
size_t obl, needed;
struct ks_msg *m;
mib[0] = CTL_NET;
mib[1] = PF_ROUTE;
mib[2] = 0;
mib[3] = BIRD_PF;
mib[4] = cmd;
mib[5] = 0;
if (sysctl(mib, 6 , NULL , &needed, NULL, 0) < 0)
{
die("RT scan...");
}
obl = *bl;
while (needed > *bl) *bl *= 2;
while (needed < (*bl/2)) *bl /= 2;
if ((obl!=*bl) || !*buf)
{
if (*buf) mb_free(*buf);
if ((*buf = mb_alloc(pool, *bl)) == NULL) die("RT scan buf alloc");
}
on = needed;
if (sysctl(mib, 6 , *buf, &needed, NULL, 0) < 0)
{
if (on != needed) return; /* The buffer size changed since last sysctl */
die("RT scan 2");
}
for (next = *buf; next < (*buf + needed); next += m->rtm.rtm_msglen)
{
m = (struct ks_msg *)next;
krt_read_msg(p, m, 1);
}
}
static byte *krt_buffer = NULL;
static byte *kif_buffer = NULL;
static size_t krt_buflen = 32768;
static size_t kif_buflen = 4096;
void
krt_scan_fire(struct krt_proto *p)
{
krt_sysctl_scan((struct proto *)p, p->krt_pool, &krt_buffer, &krt_buflen, NET_RT_DUMP);
}
void
krt_if_scan(struct kif_proto *p)
{
struct proto *P = (struct proto *)p;
if_start_update();
krt_sysctl_scan(P, P->pool, &kif_buffer, &kif_buflen, NET_RT_IFLIST);
if_end_update();
}
void
krt_set_construct(struct krt_config *c UNUSED)
{
}
void
krt_set_shutdown(struct krt_proto *x UNUSED, int last UNUSED)
{
mb_free(krt_buffer);
krt_buffer = NULL;
}
void
krt_if_io_init(void)
{
}
void
krt_if_construct(struct kif_config *c UNUSED)
{
}
void
krt_if_start(struct kif_proto *p UNUSED)
{
}
void
krt_if_shutdown(struct kif_proto *p UNUSED)
{
mb_free(kif_buffer);
kif_buffer = NULL;
}