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bird/sysdep/linux/netlink/netlink.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

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/*
* BIRD -- Linux Netlink Interface
*
* (c) 1999--2000 Martin Mares <mj@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#include <stdio.h>
#include <fcntl.h>
#include <net/if.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <errno.h>
#undef LOCAL_DEBUG
#include "nest/bird.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/socket.h"
#include "lib/string.h"
#include "conf/conf.h"
#include <asm/types.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#ifndef MSG_TRUNC /* Hack: Several versions of glibc miss this one :( */
#define MSG_TRUNC 0x20
#endif
/*
* Synchronous Netlink interface
*/
struct nl_sock
{
int fd;
u32 seq;
byte *rx_buffer; /* Receive buffer */
struct nlmsghdr *last_hdr; /* Recently received packet */
unsigned int last_size;
};
#define NL_RX_SIZE 8192
static struct nl_sock nl_scan = {.fd = -1}; /* Netlink socket for synchronous scan */
static struct nl_sock nl_req = {.fd = -1}; /* Netlink socket for requests */
static void
nl_open_sock(struct nl_sock *nl)
{
if (nl->fd < 0)
{
nl->fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
if (nl->fd < 0)
die("Unable to open rtnetlink socket: %m");
nl->seq = now;
nl->rx_buffer = xmalloc(NL_RX_SIZE);
nl->last_hdr = NULL;
nl->last_size = 0;
}
}
static void
nl_open(void)
{
nl_open_sock(&nl_scan);
nl_open_sock(&nl_req);
}
static void
nl_send(struct nl_sock *nl, struct nlmsghdr *nh)
{
struct sockaddr_nl sa;
memset(&sa, 0, sizeof(sa));
sa.nl_family = AF_NETLINK;
nh->nlmsg_pid = 0;
nh->nlmsg_seq = ++(nl->seq);
if (sendto(nl->fd, nh, nh->nlmsg_len, 0, (struct sockaddr *)&sa, sizeof(sa)) < 0)
die("rtnetlink sendto: %m");
nl->last_hdr = NULL;
}
static void
nl_request_dump(int cmd)
{
struct {
struct nlmsghdr nh;
struct rtgenmsg g;
} req;
req.nh.nlmsg_type = cmd;
req.nh.nlmsg_len = sizeof(req);
req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
req.g.rtgen_family = BIRD_PF;
nl_send(&nl_scan, &req.nh);
}
static struct nlmsghdr *
nl_get_reply(struct nl_sock *nl)
{
for(;;)
{
if (!nl->last_hdr)
{
struct iovec iov = { nl->rx_buffer, NL_RX_SIZE };
struct sockaddr_nl sa;
struct msghdr m = { (struct sockaddr *) &sa, sizeof(sa), &iov, 1, NULL, 0, 0 };
int x = recvmsg(nl->fd, &m, 0);
if (x < 0)
die("nl_get_reply: %m");
if (sa.nl_pid) /* It isn't from the kernel */
{
DBG("Non-kernel packet\n");
continue;
}
nl->last_size = x;
nl->last_hdr = (void *) nl->rx_buffer;
if (m.msg_flags & MSG_TRUNC)
bug("nl_get_reply: got truncated reply which should be impossible");
}
if (NLMSG_OK(nl->last_hdr, nl->last_size))
{
struct nlmsghdr *h = nl->last_hdr;
nl->last_hdr = NLMSG_NEXT(h, nl->last_size);
if (h->nlmsg_seq != nl->seq)
{
log(L_WARN "nl_get_reply: Ignoring out of sequence netlink packet (%x != %x)",
h->nlmsg_seq, nl->seq);
continue;
}
return h;
}
if (nl->last_size)
log(L_WARN "nl_get_reply: Found packet remnant of size %d", nl->last_size);
nl->last_hdr = NULL;
}
}
static struct rate_limit rl_netlink_err;
static int
nl_error(struct nlmsghdr *h)
{
struct nlmsgerr *e;
int ec;
if (h->nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr)))
{
log(L_WARN "Netlink: Truncated error message received");
return ENOBUFS;
}
e = (struct nlmsgerr *) NLMSG_DATA(h);
ec = -e->error;
if (ec)
log_rl(&rl_netlink_err, L_WARN "Netlink: %s", strerror(ec));
return ec;
}
static struct nlmsghdr *
nl_get_scan(void)
{
struct nlmsghdr *h = nl_get_reply(&nl_scan);
if (h->nlmsg_type == NLMSG_DONE)
return NULL;
if (h->nlmsg_type == NLMSG_ERROR)
{
nl_error(h);
return NULL;
}
return h;
}
static int
nl_exchange(struct nlmsghdr *pkt)
{
struct nlmsghdr *h;
nl_send(&nl_req, pkt);
for(;;)
{
h = nl_get_reply(&nl_req);
if (h->nlmsg_type == NLMSG_ERROR)
break;
log(L_WARN "nl_exchange: Unexpected reply received");
}
return nl_error(h);
}
/*
* Netlink attributes
*/
static int nl_attr_len;
static void *
nl_checkin(struct nlmsghdr *h, int lsize)
{
nl_attr_len = h->nlmsg_len - NLMSG_LENGTH(lsize);
if (nl_attr_len < 0)
{
log(L_ERR "nl_checkin: underrun by %d bytes", -nl_attr_len);
return NULL;
}
return NLMSG_DATA(h);
}
static int
nl_parse_attrs(struct rtattr *a, struct rtattr **k, int ksize)
{
int max = ksize / sizeof(struct rtattr *);
bzero(k, ksize);
while (RTA_OK(a, nl_attr_len))
{
if (a->rta_type < max)
k[a->rta_type] = a;
a = RTA_NEXT(a, nl_attr_len);
}
if (nl_attr_len)
{
log(L_ERR "nl_parse_attrs: remnant of size %d", nl_attr_len);
return 0;
}
else
return 1;
}
static void
nl_add_attr_u32(struct nlmsghdr *h, unsigned maxsize, int code, u32 data)
{
unsigned len = RTA_LENGTH(4);
struct rtattr *a;
if (NLMSG_ALIGN(h->nlmsg_len) + len > maxsize)
bug("nl_add_attr32: packet buffer overflow");
a = (struct rtattr *)((char *)h + NLMSG_ALIGN(h->nlmsg_len));
a->rta_type = code;
a->rta_len = len;
memcpy(RTA_DATA(a), &data, 4);
h->nlmsg_len = NLMSG_ALIGN(h->nlmsg_len) + len;
}
static void
nl_add_attr_ipa(struct nlmsghdr *h, unsigned maxsize, int code, ip_addr ipa)
{
unsigned len = RTA_LENGTH(sizeof(ipa));
struct rtattr *a;
if (NLMSG_ALIGN(h->nlmsg_len) + len > maxsize)
bug("nl_add_attr_ipa: packet buffer overflow");
a = (struct rtattr *)((char *)h + NLMSG_ALIGN(h->nlmsg_len));
a->rta_type = code;
a->rta_len = len;
ipa_hton(ipa);
memcpy(RTA_DATA(a), &ipa, sizeof(ipa));
h->nlmsg_len = NLMSG_ALIGN(h->nlmsg_len) + len;
}
/*
* Scanning of interfaces
*/
static void
nl_parse_link(struct nlmsghdr *h, int scan)
{
struct ifinfomsg *i;
struct rtattr *a[IFLA_WIRELESS+1];
int new = h->nlmsg_type == RTM_NEWLINK;
struct iface f;
struct iface *ifi;
char *name;
u32 mtu;
unsigned int fl;
if (!(i = nl_checkin(h, sizeof(*i))) || !nl_parse_attrs(IFLA_RTA(i), a, sizeof(a)))
return;
if (!a[IFLA_IFNAME] || RTA_PAYLOAD(a[IFLA_IFNAME]) < 2 ||
!a[IFLA_MTU] || RTA_PAYLOAD(a[IFLA_MTU]) != 4)
{
if (scan || !a[IFLA_WIRELESS])
log(L_ERR "nl_parse_link: Malformed message received");
return;
}
name = RTA_DATA(a[IFLA_IFNAME]);
memcpy(&mtu, RTA_DATA(a[IFLA_MTU]), sizeof(u32));
ifi = if_find_by_index(i->ifi_index);
if (!new)
{
DBG("KIF: IF%d(%s) goes down\n", i->ifi_index, name);
if (ifi && !scan)
{
memcpy(&f, ifi, sizeof(struct iface));
f.flags |= IF_ADMIN_DOWN;
if_update(&f);
}
}
else
{
DBG("KIF: IF%d(%s) goes up (mtu=%d,flg=%x)\n", i->ifi_index, name, mtu, i->ifi_flags);
if (ifi)
memcpy(&f, ifi, sizeof(f));
else
{
bzero(&f, sizeof(f));
f.index = i->ifi_index;
}
strncpy(f.name, RTA_DATA(a[IFLA_IFNAME]), sizeof(f.name)-1);
f.mtu = mtu;
f.flags = 0;
fl = i->ifi_flags;
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_update(&f);
}
}
static void
nl_parse_addr(struct nlmsghdr *h)
{
struct ifaddrmsg *i;
struct rtattr *a[IFA_ANYCAST+1];
int new = h->nlmsg_type == RTM_NEWADDR;
struct ifa ifa;
struct iface *ifi;
int scope;
if (!(i = nl_checkin(h, sizeof(*i))) || !nl_parse_attrs(IFA_RTA(i), a, sizeof(a)))
return;
if (i->ifa_family != BIRD_AF)
return;
if (!a[IFA_ADDRESS] || RTA_PAYLOAD(a[IFA_ADDRESS]) != sizeof(ip_addr)
#ifdef IPV6
|| a[IFA_LOCAL] && RTA_PAYLOAD(a[IFA_LOCAL]) != sizeof(ip_addr)
#else
|| !a[IFA_LOCAL] || RTA_PAYLOAD(a[IFA_LOCAL]) != sizeof(ip_addr)
|| (a[IFA_BROADCAST] && RTA_PAYLOAD(a[IFA_BROADCAST]) != sizeof(ip_addr))
#endif
)
{
log(L_ERR "nl_parse_addr: Malformed message received");
return;
}
ifi = if_find_by_index(i->ifa_index);
if (!ifi)
{
log(L_ERR "KIF: Received address message for unknown interface %d", i->ifa_index);
return;
}
bzero(&ifa, sizeof(ifa));
ifa.iface = ifi;
if (i->ifa_flags & IFA_F_SECONDARY)
ifa.flags |= IA_SECONDARY;
/* IFA_LOCAL can be unset for IPv6 interfaces */
memcpy(&ifa.ip, RTA_DATA(a[IFA_LOCAL] ? : a[IFA_ADDRESS]), sizeof(ifa.ip));
ipa_ntoh(ifa.ip);
ifa.pxlen = i->ifa_prefixlen;
if (i->ifa_prefixlen > BITS_PER_IP_ADDRESS ||
i->ifa_prefixlen == BITS_PER_IP_ADDRESS - 1)
{
log(L_ERR "KIF: Invalid prefix length for interface %s: %d", ifi->name, i->ifa_prefixlen);
new = 0;
}
if (i->ifa_prefixlen == BITS_PER_IP_ADDRESS)
{
ifa.flags |= IA_UNNUMBERED;
memcpy(&ifa.opposite, RTA_DATA(a[IFA_ADDRESS]), sizeof(ifa.opposite));
ipa_ntoh(ifa.opposite);
ifa.prefix = ifa.brd = ifa.opposite;
}
else
{
ip_addr netmask = ipa_mkmask(ifa.pxlen);
ifa.prefix = ipa_and(ifa.ip, netmask);
ifa.brd = ipa_or(ifa.ip, ipa_not(netmask));
#ifndef IPV6
if (i->ifa_prefixlen == BITS_PER_IP_ADDRESS - 2)
ifa.opposite = ipa_opposite(ifa.ip, i->ifa_prefixlen);
if ((ifi->flags & IF_BROADCAST) && a[IFA_BROADCAST])
{
ip_addr xbrd;
memcpy(&xbrd, RTA_DATA(a[IFA_BROADCAST]), sizeof(xbrd));
ipa_ntoh(xbrd);
if (ipa_equal(xbrd, ifa.prefix) || ipa_equal(xbrd, ifa.brd))
ifa.brd = xbrd;
else if (ifi->flags & IF_TMP_DOWN) /* Complain only during the first scan */
log(L_ERR "KIF: Invalid broadcast address %I for %s", xbrd, ifi->name);
}
#endif
}
scope = ipa_classify(ifa.ip);
if (scope < 0)
{
log(L_ERR "KIF: Invalid interface address %I for %s", ifa.ip, ifi->name);
return;
}
ifa.scope = scope & IADDR_SCOPE_MASK;
DBG("KIF: IF%d(%s): %s IPA %I, flg %x, net %I/%d, brd %I, opp %I\n",
ifi->index, ifi->name,
new ? "added" : "removed",
ifa.ip, ifa.flags, ifa.prefix, ifa.pxlen, ifa.brd, ifa.opposite);
if (new)
ifa_update(&ifa);
else
ifa_delete(&ifa);
}
void
krt_if_scan(struct kif_proto *p UNUSED)
{
struct nlmsghdr *h;
if_start_update();
nl_request_dump(RTM_GETLINK);
while (h = nl_get_scan())
if (h->nlmsg_type == RTM_NEWLINK || h->nlmsg_type == RTM_DELLINK)
nl_parse_link(h, 1);
else
log(L_DEBUG "nl_scan_ifaces: Unknown packet received (type=%d)", h->nlmsg_type);
nl_request_dump(RTM_GETADDR);
while (h = nl_get_scan())
if (h->nlmsg_type == RTM_NEWADDR || h->nlmsg_type == RTM_DELADDR)
nl_parse_addr(h);
else
log(L_DEBUG "nl_scan_ifaces: Unknown packet received (type=%d)", h->nlmsg_type);
if_end_update();
}
/*
* Routes
*/
static struct krt_proto *nl_table_map[NL_NUM_TABLES];
int
krt_capable(rte *e)
{
rta *a = e->attrs;
if (a->cast != RTC_UNICAST)
return 0;
switch (a->dest)
{
case RTD_ROUTER:
if (ipa_has_link_scope(a->gw) && (a->iface == NULL))
return 0;
case RTD_DEVICE:
case RTD_BLACKHOLE:
case RTD_UNREACHABLE:
case RTD_PROHIBIT:
break;
default:
return 0;
}
return 1;
}
static void
nl_send_route(struct krt_proto *p, rte *e, int new)
{
net *net = e->net;
rta *a = e->attrs;
struct {
struct nlmsghdr h;
struct rtmsg r;
char buf[128];
} r;
DBG("nl_send_route(%I/%d,new=%d)\n", net->n.prefix, net->n.pxlen, new);
bzero(&r.h, sizeof(r.h));
bzero(&r.r, sizeof(r.r));
r.h.nlmsg_type = new ? RTM_NEWROUTE : RTM_DELROUTE;
r.h.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
r.h.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | (new ? NLM_F_CREATE|NLM_F_EXCL : 0);
r.r.rtm_family = BIRD_AF;
r.r.rtm_dst_len = net->n.pxlen;
r.r.rtm_tos = 0;
r.r.rtm_table = KRT_CF->scan.table_id;
r.r.rtm_protocol = RTPROT_BIRD;
r.r.rtm_scope = RT_SCOPE_UNIVERSE;
nl_add_attr_ipa(&r.h, sizeof(r), RTA_DST, net->n.prefix);
switch (a->dest)
{
case RTD_ROUTER:
r.r.rtm_type = RTN_UNICAST;
nl_add_attr_ipa(&r.h, sizeof(r), RTA_GATEWAY, a->gw);
/* a->iface != NULL checked in krt_capable() */
if (ipa_has_link_scope(a->gw))
nl_add_attr_u32(&r.h, sizeof(r), RTA_OIF, a->iface->index);
break;
case RTD_DEVICE:
if (!a->iface)
return;
r.r.rtm_type = RTN_UNICAST;
nl_add_attr_u32(&r.h, sizeof(r), RTA_OIF, a->iface->index);
break;
case RTD_BLACKHOLE:
r.r.rtm_type = RTN_BLACKHOLE;
break;
case RTD_UNREACHABLE:
r.r.rtm_type = RTN_UNREACHABLE;
break;
case RTD_PROHIBIT:
r.r.rtm_type = RTN_PROHIBIT;
break;
default:
bug("krt_capable inconsistent with nl_send_route");
}
nl_exchange(&r.h);
}
void
krt_set_notify(struct krt_proto *p, net *n UNUSED, rte *new, rte *old)
{
if (old)
nl_send_route(p, old, 0);
if (new)
nl_send_route(p, new, 1);
}
#define SKIP(ARG...) do { DBG("KRT: Ignoring route - " ARG); return; } while(0)
static void
nl_parse_route(struct nlmsghdr *h, int scan)
{
struct krt_proto *p;
struct rtmsg *i;
struct rtattr *a[RTA_CACHEINFO+1];
int new = h->nlmsg_type == RTM_NEWROUTE;
ip_addr dst;
rta ra;
rte *e;
net *net;
u32 oif;
int src;
if (!(i = nl_checkin(h, sizeof(*i))) || !nl_parse_attrs(RTM_RTA(i), a, sizeof(a)))
return;
if (i->rtm_family != BIRD_AF)
return;
if ((a[RTA_DST] && RTA_PAYLOAD(a[RTA_DST]) != sizeof(ip_addr)) ||
(a[RTA_OIF] && RTA_PAYLOAD(a[RTA_OIF]) != 4) ||
(a[RTA_PRIORITY] && RTA_PAYLOAD(a[RTA_PRIORITY]) != 4) ||
#ifdef IPV6
(a[RTA_IIF] && RTA_PAYLOAD(a[RTA_IIF]) != 4) ||
#endif
(a[RTA_GATEWAY] && RTA_PAYLOAD(a[RTA_GATEWAY]) != sizeof(ip_addr)))
{
log(L_ERR "KRT: Malformed message received");
return;
}
if (a[RTA_DST])
{
memcpy(&dst, RTA_DATA(a[RTA_DST]), sizeof(dst));
ipa_ntoh(dst);
}
else
dst = IPA_NONE;
if (a[RTA_OIF])
memcpy(&oif, RTA_DATA(a[RTA_OIF]), sizeof(oif));
else
oif = ~0;
DBG("KRT: Got %I/%d, type=%d, oif=%d, table=%d, prid=%d, proto=%s\n", dst, i->rtm_dst_len, i->rtm_type, oif, i->rtm_table, i->rtm_protocol, p->p.name);
p = nl_table_map[i->rtm_table]; /* Do we know this table? */
if (!p)
SKIP("unknown table %d", i->rtm_table);
#ifdef IPV6
if (a[RTA_IIF])
SKIP("IIF set\n");
#else
if (i->rtm_tos != 0) /* We don't support TOS */
SKIP("TOS %02x\n", i->rtm_tos);
#endif
if (scan && !new)
SKIP("RTM_DELROUTE in scan\n");
int c = ipa_classify_net(dst);
if ((c < 0) || !(c & IADDR_HOST) || ((c & IADDR_SCOPE_MASK) <= SCOPE_LINK))
SKIP("strange class/scope\n");
// ignore rtm_scope, it is not a real scope
// if (i->rtm_scope != RT_SCOPE_UNIVERSE)
// SKIP("scope %u\n", i->rtm_scope);
switch (i->rtm_protocol)
{
case RTPROT_UNSPEC:
SKIP("proto unspec\n");
case RTPROT_REDIRECT:
src = KRT_SRC_REDIRECT;
break;
case RTPROT_KERNEL:
src = KRT_SRC_KERNEL;
return;
case RTPROT_BIRD:
if (!scan)
SKIP("echo\n");
src = KRT_SRC_BIRD;
break;
case RTPROT_BOOT:
default:
src = KRT_SRC_ALIEN;
}
net = net_get(p->p.table, dst, i->rtm_dst_len);
ra.proto = &p->p;
ra.source = RTS_INHERIT;
ra.scope = SCOPE_UNIVERSE;
ra.cast = RTC_UNICAST;
ra.flags = ra.aflags = 0;
ra.from = IPA_NONE;
ra.gw = IPA_NONE;
ra.iface = NULL;
ra.eattrs = NULL;
switch (i->rtm_type)
{
case RTN_UNICAST:
ra.iface = if_find_by_index(oif);
if (!ra.iface)
{
log(L_ERR "KRT: Received route %I/%d with unknown ifindex %u",
net->n.prefix, net->n.pxlen, oif);
return;
}
if (a[RTA_GATEWAY])
{
neighbor *ng;
ra.dest = RTD_ROUTER;
memcpy(&ra.gw, RTA_DATA(a[RTA_GATEWAY]), sizeof(ra.gw));
ipa_ntoh(ra.gw);
ng = neigh_find2(&p->p, &ra.gw, ra.iface,
(i->rtm_flags & RTNH_F_ONLINK) ? NEF_ONLINK : 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, ra.gw);
return;
}
}
else
{
ra.dest = RTD_DEVICE;
/*
* In Linux IPv6, 'native' device routes have proto
* RTPROT_BOOT and not RTPROT_KERNEL (which they have in
* IPv4 and which is expected). We cannot distinguish
* 'native' and user defined device routes, so we ignore all
* such device routes and for consistency, we have the same
* behavior in IPv4. Anyway, users should use RTPROT_STATIC
* for their 'alien' routes.
*/
if (i->rtm_protocol == RTPROT_BOOT)
src = KRT_SRC_KERNEL;
}
break;
case RTN_BLACKHOLE:
ra.dest = RTD_BLACKHOLE;
break;
case RTN_UNREACHABLE:
ra.dest = RTD_UNREACHABLE;
break;
case RTN_PROHIBIT:
ra.dest = RTD_PROHIBIT;
break;
/* FIXME: What about RTN_THROW? */
default:
SKIP("type %d\n", i->rtm_type);
return;
}
e = rte_get_temp(&ra);
e->net = net;
e->u.krt.src = src;
e->u.krt.proto = i->rtm_protocol;
e->u.krt.type = i->rtm_type;
if (a[RTA_PRIORITY])
memcpy(&e->u.krt.metric, RTA_DATA(a[RTA_PRIORITY]), sizeof(e->u.krt.metric));
else
e->u.krt.metric = 0;
if (scan)
krt_got_route(p, e);
else
krt_got_route_async(p, e, new);
}
void
krt_scan_fire(struct krt_proto *p UNUSED) /* CONFIG_ALL_TABLES_AT_ONCE => p is NULL */
{
struct nlmsghdr *h;
nl_request_dump(RTM_GETROUTE);
while (h = nl_get_scan())
if (h->nlmsg_type == RTM_NEWROUTE || h->nlmsg_type == RTM_DELROUTE)
nl_parse_route(h, 1);
else
log(L_DEBUG "nl_scan_fire: Unknown packet received (type=%d)", h->nlmsg_type);
}
/*
* Asynchronous Netlink interface
*/
static sock *nl_async_sk; /* BIRD socket for asynchronous notifications */
static byte *nl_async_rx_buffer; /* Receive buffer */
static void
nl_async_msg(struct nlmsghdr *h)
{
switch (h->nlmsg_type)
{
case RTM_NEWROUTE:
case RTM_DELROUTE:
DBG("KRT: Received async route notification (%d)\n", h->nlmsg_type);
nl_parse_route(h, 0);
break;
case RTM_NEWLINK:
case RTM_DELLINK:
DBG("KRT: Received async link notification (%d)\n", h->nlmsg_type);
nl_parse_link(h, 0);
break;
case RTM_NEWADDR:
case RTM_DELADDR:
DBG("KRT: Received async address notification (%d)\n", h->nlmsg_type);
nl_parse_addr(h);
break;
default:
DBG("KRT: Received unknown async notification (%d)\n", h->nlmsg_type);
}
}
static int
nl_async_hook(sock *sk, int size UNUSED)
{
struct iovec iov = { nl_async_rx_buffer, NL_RX_SIZE };
struct sockaddr_nl sa;
struct msghdr m = { (struct sockaddr *) &sa, sizeof(sa), &iov, 1, NULL, 0, 0 };
struct nlmsghdr *h;
int x;
unsigned int len;
x = recvmsg(sk->fd, &m, 0);
if (x < 0)
{
if (errno == ENOBUFS)
{
/*
* Netlink reports some packets have been thrown away.
* One day we might react to it by asking for route table
* scan in near future.
*/
return 1; /* More data are likely to be ready */
}
else if (errno != EWOULDBLOCK)
log(L_ERR "Netlink recvmsg: %m");
return 0;
}
if (sa.nl_pid) /* It isn't from the kernel */
{
DBG("Non-kernel packet\n");
return 1;
}
h = (void *) nl_async_rx_buffer;
len = x;
if (m.msg_flags & MSG_TRUNC)
{
log(L_WARN "Netlink got truncated asynchronous message");
return 1;
}
while (NLMSG_OK(h, len))
{
nl_async_msg(h);
h = NLMSG_NEXT(h, len);
}
if (len)
log(L_WARN "nl_async_hook: Found packet remnant of size %d", len);
return 1;
}
static void
nl_open_async(void)
{
sock *sk;
struct sockaddr_nl sa;
int fd;
static int nl_open_tried = 0;
if (nl_open_tried)
return;
nl_open_tried = 1;
DBG("KRT: Opening async netlink socket\n");
fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
if (fd < 0)
{
log(L_ERR "Unable to open asynchronous rtnetlink socket: %m");
return;
}
bzero(&sa, sizeof(sa));
sa.nl_family = AF_NETLINK;
#ifdef IPV6
sa.nl_groups = RTMGRP_LINK | RTMGRP_IPV6_IFADDR | RTMGRP_IPV6_ROUTE;
#else
sa.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR | RTMGRP_IPV4_ROUTE;
#endif
if (bind(fd, (struct sockaddr *) &sa, sizeof(sa)) < 0)
{
log(L_ERR "Unable to bind asynchronous rtnetlink socket: %m");
return;
}
sk = nl_async_sk = sk_new(krt_pool);
sk->type = SK_MAGIC;
sk->rx_hook = nl_async_hook;
sk->fd = fd;
if (sk_open(sk))
bug("Netlink: sk_open failed");
if (!nl_async_rx_buffer)
nl_async_rx_buffer = xmalloc(NL_RX_SIZE);
}
/*
* Interface to the UNIX krt module
*/
static u8 nl_cf_table[(NL_NUM_TABLES+7) / 8];
void
krt_scan_preconfig(struct config *c UNUSED)
{
bzero(&nl_cf_table, sizeof(nl_cf_table));
}
void
krt_scan_postconfig(struct krt_config *x)
{
int id = x->scan.table_id;
if (nl_cf_table[id/8] & (1 << (id%8)))
cf_error("Multiple kernel syncers defined for table #%d", id);
nl_cf_table[id/8] |= (1 << (id%8));
}
void
krt_scan_construct(struct krt_config *x)
{
#ifndef IPV6
x->scan.table_id = RT_TABLE_MAIN;
#else
x->scan.table_id = 254;
#endif
}
void
krt_scan_start(struct krt_proto *p, int first)
{
init_list(&p->scan.temp_ifs);
nl_table_map[KRT_CF->scan.table_id] = p;
if (first)
{
nl_open();
nl_open_async();
}
}
void
krt_scan_shutdown(struct krt_proto *p UNUSED, int last UNUSED)
{
}
void
krt_if_start(struct kif_proto *p UNUSED)
{
nl_open();
nl_open_async();
}
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