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/*
* Zebra Policy Based Routing (PBR) interaction with the kernel using
* netlink.
* Copyright (C) 2018 Cumulus Networks, Inc.
*
* This file is part of FRR.
*
* FRR is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2, or (at your option) any
* later version.
*
* FRR 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
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with FRR; see the file COPYING. If not, write to the Free
* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA.
*/
#include <zebra.h>
#ifdef HAVE_NETLINK
#include "if.h"
#include "prefix.h"
#include "vrf.h"
#include <linux/fib_rules.h>
#include "zebra/zserv.h"
#include "zebra/zebra_ns.h"
#include "zebra/zebra_vrf.h"
#include "zebra/rt.h"
#include "zebra/interface.h"
#include "zebra/debug.h"
#include "zebra/rtadv.h"
#include "zebra/kernel_netlink.h"
#include "zebra/rule_netlink.h"
#include "zebra/zebra_pbr.h"
/* definitions */
/* static function declarations */
/* Private functions */
/* Install or uninstall specified rule for a specific interface.
* Form netlink message and ship it. Currently, notify status after
* waiting for netlink status.
*/
static int netlink_rule_update(int cmd, struct zebra_pbr_rule *rule)
{
int family;
int bytelen;
struct {
struct nlmsghdr n;
struct fib_rule_hdr frh;
char buf[NL_PKT_BUF_SIZE];
} req;
struct zebra_ns *zns = zebra_ns_lookup(NS_DEFAULT);
struct sockaddr_nl snl;
char buf1[PREFIX_STRLEN];
char buf2[PREFIX_STRLEN];
memset(&req, 0, sizeof(req) - NL_PKT_BUF_SIZE);
family = PREFIX_FAMILY(&rule->filter.src_ip);
bytelen = (family == AF_INET ? 4 : 16);
req.n.nlmsg_type = cmd;
req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
req.n.nlmsg_flags = NLM_F_REQUEST;
req.n.nlmsg_pid = zns->netlink_cmd.snl.nl_pid;
req.frh.family = family;
req.frh.action = FR_ACT_TO_TBL;
/* rule's pref # */
addattr32(&req.n, sizeof(req), FRA_PRIORITY, rule->priority);
/* interface on which applied */
if (rule->ifp)
addattr_l(&req.n, sizeof(req), FRA_IFNAME, rule->ifp->name,
strlen(rule->ifp->name) + 1);
/* source IP, if specified */
if (IS_RULE_FILTERING_ON_SRC_IP(rule)) {
req.frh.src_len = rule->filter.src_ip.prefixlen;
addattr_l(&req.n, sizeof(req), FRA_SRC,
&rule->filter.src_ip.u.prefix, bytelen);
}
/* destination IP, if specified */
if (IS_RULE_FILTERING_ON_DST_IP(rule)) {
req.frh.dst_len = rule->filter.dst_ip.prefixlen;
addattr_l(&req.n, sizeof(req), FRA_DST,
&rule->filter.dst_ip.u.prefix, bytelen);
}
/* Route table to use to forward, if filter criteria matches. */
if (rule->action.table < 256)
req.frh.table = rule->action.table;
else {
req.frh.table = RT_TABLE_UNSPEC;
addattr32(&req.n, sizeof(req), FRA_TABLE,
rule->action.table);
}
if (IS_ZEBRA_DEBUG_KERNEL)
zlog_debug(
"Tx %s family %s IF %s(%u) Pref %u Src %s Dst %s Table %u",
nl_msg_type_to_str(cmd), nl_family_to_str(family),
rule->ifp ? rule->ifp->name : "Unknown",
rule->ifp ? rule->ifp->ifindex : 0, rule->priority,
prefix2str(&rule->filter.src_ip, buf1, sizeof(buf1)),
prefix2str(&rule->filter.dst_ip, buf2, sizeof(buf2)),
rule->action.table);
/* Ship off the message.
* Note: Currently, netlink_talk() is a blocking call which returns
* back the status.
*/
memset(&snl, 0, sizeof(snl));
snl.nl_family = AF_NETLINK;
return netlink_talk(netlink_talk_filter, &req.n,
&zns->netlink_cmd, zns, 0);
}
/* Public functions */
/*
* Install specified rule for a specific interface. The preference is what
* goes in the rule to denote relative ordering; it may or may not be the
* same as the rule's user-defined sequence number.
*/
void kernel_add_pbr_rule(struct zebra_pbr_rule *rule)
{
int ret = 0;
ret = netlink_rule_update(RTM_NEWRULE, rule);
kernel_pbr_rule_add_del_status(rule,
(!ret) ? SOUTHBOUND_INSTALL_SUCCESS
: SOUTHBOUND_INSTALL_FAILURE);
}
/*
* Uninstall specified rule for a specific interface.
*/
void kernel_del_pbr_rule(struct zebra_pbr_rule *rule)
{
int ret = 0;
ret = netlink_rule_update(RTM_DELRULE, rule);
kernel_pbr_rule_add_del_status(rule,
(!ret) ? SOUTHBOUND_DELETE_SUCCESS
: SOUTHBOUND_DELETE_FAILURE);
}
/*
* Handle netlink notification informing a rule add or delete.
* Handling of an ADD is TBD.
* DELs are notified up, if other attributes indicate it may be a
* notification of interest. The expectation is that if this corresponds
* to a PBR rule added by FRR, it will be readded.
*/
int netlink_rule_change(struct sockaddr_nl *snl, struct nlmsghdr *h,
ns_id_t ns_id, int startup)
{
struct zebra_ns *zns;
struct fib_rule_hdr *frh;
struct rtattr *tb[FRA_MAX + 1];
int len;
char *ifname;
struct zebra_pbr_rule rule;
char buf1[PREFIX_STRLEN];
char buf2[PREFIX_STRLEN];
/* Basic validation followed by extracting attributes. */
if (h->nlmsg_type != RTM_NEWRULE && h->nlmsg_type != RTM_DELRULE)
return 0;
/* TBD */
if (h->nlmsg_type == RTM_NEWRULE)
return 0;
len = h->nlmsg_len - NLMSG_LENGTH(sizeof(struct fib_rule_hdr));
if (len < 0)
return -1;
frh = NLMSG_DATA(h);
if (frh->family != AF_INET && frh->family != AF_INET6)
return 0;
if (frh->action != FR_ACT_TO_TBL)
return 0;
memset(tb, 0, sizeof(tb));
netlink_parse_rtattr(tb, FRA_MAX, RTM_RTA(frh), len);
/* TBD: We don't care about rules not specifying an IIF. */
if (tb[FRA_IFNAME] == NULL)
return 0;
/* If we don't know the interface, we don't care. */
ifname = (char *)RTA_DATA(tb[FRA_IFNAME]);
zns = zebra_ns_lookup(ns_id);
rule.ifp = if_lookup_by_name_per_ns(zns, ifname);
if (!rule.ifp)
return 0;
memset(&rule, 0, sizeof(rule));
if (tb[FRA_PRIORITY])
rule.priority = *(uint32_t *)RTA_DATA(tb[FRA_PRIORITY]);
if (tb[FRA_SRC]) {
if (frh->family == AF_INET)
memcpy(&rule.filter.src_ip.u.prefix4,
RTA_DATA(tb[FRA_SRC]), 4);
else
memcpy(&rule.filter.src_ip.u.prefix6,
RTA_DATA(tb[FRA_SRC]), 16);
rule.filter.src_ip.prefixlen = frh->src_len;
rule.filter.filter_bm |= PBR_FILTER_SRC_IP;
}
if (tb[FRA_DST]) {
if (frh->family == AF_INET)
memcpy(&rule.filter.dst_ip.u.prefix4,
RTA_DATA(tb[FRA_DST]), 4);
else
memcpy(&rule.filter.dst_ip.u.prefix6,
RTA_DATA(tb[FRA_DST]), 16);
rule.filter.dst_ip.prefixlen = frh->dst_len;
rule.filter.filter_bm |= PBR_FILTER_DST_IP;
}
if (tb[FRA_TABLE])
rule.action.table = *(uint32_t *)RTA_DATA(tb[FRA_TABLE]);
else
rule.action.table = frh->table;
if (IS_ZEBRA_DEBUG_KERNEL)
zlog_debug(
"Rx %s family %s IF %s(%u) Pref %u Src %s Dst %s Table %u",
nl_msg_type_to_str(h->nlmsg_type),
nl_family_to_str(frh->family), rule.ifp->name,
rule.ifp->ifindex, rule.priority,
prefix2str(&rule.filter.src_ip, buf1, sizeof(buf1)),
prefix2str(&rule.filter.dst_ip, buf2, sizeof(buf2)),
rule.action.table);
return kernel_pbr_rule_del(&rule);
}
/*
* Get to know existing PBR rules in the kernel - typically called at startup.
* TBD.
*/
int netlink_rules_read(struct zebra_ns *zns)
{
return 0;
}
#endif /* HAVE_NETLINK */
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