net/route/route_helpers.c

/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2020 Alexander V. Chernikov
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_inet.h"
#include "opt_inet6.h"
#include "opt_route.h"

#include <sys/param.h>
#include <sys/jail.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/sysproto.h>
#include <sys/proc.h>
#include <sys/domain.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/rmlock.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <net/route/route_ctl.h>
#include <net/route/route_var.h>
#include <net/route/nhop_utils.h>
#include <net/route/nhop.h>
#include <net/route/nhop_var.h>
#ifdef INET
#include <netinet/in_fib.h>
#endif
#ifdef INET6
#include <netinet6/in6_fib.h>
#include <netinet6/in6_var.h>
#endif
#include <net/vnet.h>

#define	DEBUG_MOD_NAME	rt_helpers
#define	DEBUG_MAX_LEVEL	LOG_DEBUG2
#include <net/route/route_debug.h>
_DECLARE_DEBUG(LOG_INFO);

/*
 * RIB helper functions.
 */

void
rib_walk_ext_locked(struct rib_head *rnh, rib_walktree_f_t *wa_f,
    rib_walk_hook_f_t *hook_f, void *arg)
{
	if (hook_f != NULL)
		hook_f(rnh, RIB_WALK_HOOK_PRE, arg);
	rnh->rnh_walktree(&rnh->head, (walktree_f_t *)wa_f, arg);
	if (hook_f != NULL)
		hook_f(rnh, RIB_WALK_HOOK_POST, arg);
}

/*
 * Calls @wa_f with @arg for each entry in the table specified by
 * @af and @fibnum.
 *
 * @ss_t callback is called before and after the tree traversal
 *  while holding table lock.
 *
 * Table is traversed under read lock unless @wlock is set.
 */
void
rib_walk_ext_internal(struct rib_head *rnh, bool wlock, rib_walktree_f_t *wa_f,
    rib_walk_hook_f_t *hook_f, void *arg)
{
	RIB_RLOCK_TRACKER;

	if (wlock)
		RIB_WLOCK(rnh);
	else
		RIB_RLOCK(rnh);
	rib_walk_ext_locked(rnh, wa_f, hook_f, arg);
	if (wlock)
		RIB_WUNLOCK(rnh);
	else
		RIB_RUNLOCK(rnh);
}

void
rib_walk_ext(uint32_t fibnum, int family, bool wlock, rib_walktree_f_t *wa_f,
    rib_walk_hook_f_t *hook_f, void *arg)
{
	struct rib_head *rnh;

	if ((rnh = rt_tables_get_rnh(fibnum, family)) != NULL)
		rib_walk_ext_internal(rnh, wlock, wa_f, hook_f, arg);
}

/*
 * Calls @wa_f with @arg for each entry in the table specified by
 * @af and @fibnum.
 *
 * Table is traversed under read lock unless @wlock is set.
 */
void
rib_walk(uint32_t fibnum, int family, bool wlock, rib_walktree_f_t *wa_f,
    void *arg)
{

	rib_walk_ext(fibnum, family, wlock, wa_f, NULL, arg);
}

/*
 * Calls @wa_f with @arg for each entry in the table matching @prefix/@mask.
 *
 * The following flags are supported:
 *  RIB_FLAG_WLOCK: acquire exclusive lock
 *  RIB_FLAG_LOCKED: Assumes the table is already locked & skip locking
 *
 * By default, table is traversed under read lock.
 */
void
rib_walk_from(uint32_t fibnum, int family, uint32_t flags, struct sockaddr *prefix,
    struct sockaddr *mask, rib_walktree_f_t *wa_f, void *arg)
{
	RIB_RLOCK_TRACKER;
	struct rib_head *rnh = rt_tables_get_rnh(fibnum, family);

	if (rnh == NULL)
		return;

	if (flags & RIB_FLAG_WLOCK)
		RIB_WLOCK(rnh);
	else if (!(flags & RIB_FLAG_LOCKED))
		RIB_RLOCK(rnh);

	rnh->rnh_walktree_from(&rnh->head, prefix, mask, (walktree_f_t *)wa_f, arg);

	if (flags & RIB_FLAG_WLOCK)
		RIB_WUNLOCK(rnh);
	else if (!(flags & RIB_FLAG_LOCKED))
		RIB_RUNLOCK(rnh);
}

/*
 * Iterates over all existing fibs in system calling
 *  @hook_f function before/after traversing each fib.
 *  Calls @wa_f function for each element in current fib.
 * If af is not AF_UNSPEC, iterates over fibs in particular
 * address family.
 */
void
rib_foreach_table_walk(int family, bool wlock, rib_walktree_f_t *wa_f,
    rib_walk_hook_f_t *hook_f, void *arg)
{

	for (uint32_t fibnum = 0; fibnum < rt_numfibs; fibnum++) {
		/* Do we want some specific family? */
		if (family != AF_UNSPEC) {
			rib_walk_ext(fibnum, family, wlock, wa_f, hook_f, arg);
			continue;
		}

		for (int i = 1; i <= AF_MAX; i++)
			rib_walk_ext(fibnum, i, wlock, wa_f, hook_f, arg);
	}
}

/*
 * Iterates over all existing fibs in system and deletes each element
 *  for which @filter_f function returns non-zero value.
 * If @family is not AF_UNSPEC, iterates over fibs in particular
 * address family.
 */
void
rib_foreach_table_walk_del(int family, rib_filter_f_t *filter_f, void *arg)
{

	for (uint32_t fibnum = 0; fibnum < rt_numfibs; fibnum++) {
		/* Do we want some specific family? */
		if (family != AF_UNSPEC) {
			rib_walk_del(fibnum, family, filter_f, arg, 0);
			continue;
		}

		for (int i = 1; i <= AF_MAX; i++)
			rib_walk_del(fibnum, i, filter_f, arg, 0);
	}
}


/*
 * Wrapper for the control plane functions for performing af-agnostic
 *  lookups.
 * @fibnum: fib to perform the lookup.
 * @dst: sockaddr with family and addr filled in. IPv6 addresses needs to be in
 *  deembedded from.
 * @flags: fib(9) flags.
 * @flowid: flow id for path selection in multipath use case.
 *
 * Returns nhop_object or NULL.
 *
 * Requires NET_EPOCH.
 *
 */
struct nhop_object *
rib_lookup(uint32_t fibnum, const struct sockaddr *dst, uint32_t flags,
    uint32_t flowid)
{
	struct nhop_object *nh;

	nh = NULL;

	switch (dst->sa_family) {
#ifdef INET
	case AF_INET:
	{
		const struct sockaddr_in *a = (const struct sockaddr_in *)dst;
		nh = fib4_lookup(fibnum, a->sin_addr, 0, flags, flowid);
		break;
	}
#endif
#ifdef INET6
	case AF_INET6:
	{
		const struct sockaddr_in6 *a = (const struct sockaddr_in6*)dst;
		nh = fib6_lookup(fibnum, &a->sin6_addr, a->sin6_scope_id,
		    flags, flowid);
		break;
	}
#endif
	}

	return (nh);
}

#ifdef ROUTE_MPATH
static void
notify_add(struct rib_cmd_info *rc, const struct weightened_nhop *wn_src,
    route_notification_t *cb, void *cbdata) {
	rc->rc_nh_new = wn_src->nh;
	rc->rc_nh_weight = wn_src->weight;
#if DEBUG_MAX_LEVEL >= LOG_DEBUG2
	char nhbuf[NHOP_PRINT_BUFSIZE];
	FIB_NH_LOG(LOG_DEBUG2, wn_src->nh, "RTM_ADD for %s @ w=%u",
	    nhop_print_buf(wn_src->nh, nhbuf, sizeof(nhbuf)), wn_src->weight);
#endif
	cb(rc, cbdata);
}

static void
notify_del(struct rib_cmd_info *rc, const struct weightened_nhop *wn_src,
    route_notification_t *cb, void *cbdata) {
	rc->rc_nh_old = wn_src->nh;
	rc->rc_nh_weight = wn_src->weight;
#if DEBUG_MAX_LEVEL >= LOG_DEBUG2
	char nhbuf[NHOP_PRINT_BUFSIZE];
	FIB_NH_LOG(LOG_DEBUG2, wn_src->nh, "RTM_DEL for %s @ w=%u",
	    nhop_print_buf(wn_src->nh, nhbuf, sizeof(nhbuf)), wn_src->weight);
#endif
	cb(rc, cbdata);
}

static void
decompose_change_notification(struct rib_cmd_info *rc, route_notification_t *cb,
    void *cbdata)
{
	uint32_t num_old, num_new;
	const struct weightened_nhop *wn_old, *wn_new;
	struct weightened_nhop tmp = { NULL, 0 };
	uint32_t idx_old = 0, idx_new = 0;

	struct rib_cmd_info rc_del = { .rc_cmd = RTM_DELETE, .rc_rt = rc->rc_rt };
	struct rib_cmd_info rc_add = { .rc_cmd = RTM_ADD, .rc_rt = rc->rc_rt };

	if (NH_IS_NHGRP(rc->rc_nh_old)) {
		wn_old = nhgrp_get_nhops((struct nhgrp_object *)rc->rc_nh_old, &num_old);
	} else {
		tmp.nh = rc->rc_nh_old;
		tmp.weight = rc->rc_nh_weight;
		wn_old = &tmp;
		num_old = 1;
	}
	if (NH_IS_NHGRP(rc->rc_nh_new)) {
		wn_new = nhgrp_get_nhops((struct nhgrp_object *)rc->rc_nh_new, &num_new);
	} else {
		tmp.nh = rc->rc_nh_new;
		tmp.weight = rc->rc_nh_weight;
		wn_new = &tmp;
		num_new = 1;
	}
#if DEBUG_MAX_LEVEL >= LOG_DEBUG
	{
		char buf_old[NHOP_PRINT_BUFSIZE], buf_new[NHOP_PRINT_BUFSIZE];
		nhop_print_buf_any(rc->rc_nh_old, buf_old, NHOP_PRINT_BUFSIZE);
		nhop_print_buf_any(rc->rc_nh_new, buf_new, NHOP_PRINT_BUFSIZE);
		FIB_NH_LOG(LOG_DEBUG, wn_old[0].nh, "change %s -> %s", buf_old, buf_new);
	}
#endif

	/* Use the fact that each @wn array is sorted */
	/*
	 * Here we have one (or two) multipath groups and transition
	 *  between them needs to be reported to the caller, using series
	 *  of primitive (RTM_DEL, RTM_ADD) operations.
	 *
	 * Leverage the fact that each nexthop group has its nexthops sorted
	 *  by their indices.
	 * [1] -> [1, 2] = A{2}
	 * [1, 2] -> [1] = D{2}
	 * [1, 2, 4] -> [1, 3, 4] = D{2}, A{3}
	 * [1, 2] -> [3, 4] = D{1}, D{2}, A{3}, A{4]
	 */
	while ((idx_old < num_old) && (idx_new < num_new)) {
		uint32_t nh_idx_old = wn_old[idx_old].nh->nh_priv->nh_idx;
		uint32_t nh_idx_new = wn_new[idx_new].nh->nh_priv->nh_idx;

		if (nh_idx_old == nh_idx_new) {
			if (wn_old[idx_old].weight != wn_new[idx_new].weight) {
				/* Update weight by providing del/add notifications */
				notify_del(&rc_del, &wn_old[idx_old], cb, cbdata);
				notify_add(&rc_add, &wn_new[idx_new], cb, cbdata);
			}
			idx_old++;
			idx_new++;
		} else if (nh_idx_old < nh_idx_new) {
			/* [1, ~2~, 4], [1, ~3~, 4] */
			notify_del(&rc_del, &wn_old[idx_old], cb, cbdata);
			idx_old++;
		} else {
			/* nh_idx_old > nh_idx_new. */
			notify_add(&rc_add, &wn_new[idx_new], cb, cbdata);
			idx_new++;
		}
	}

	while (idx_old < num_old) {
		notify_del(&rc_del, &wn_old[idx_old], cb, cbdata);
		idx_old++;
	}

	while (idx_new < num_new) {
		notify_add(&rc_add, &wn_new[idx_new], cb, cbdata);
		idx_new++;
	}
}

/*
 * Decompose multipath cmd info @rc into a list of add/del/change
 *  single-path operations, calling @cb callback for each operation.
 * Assumes at least one of the nexthops in @rc is multipath.
 */
void
rib_decompose_notification(struct rib_cmd_info *rc, route_notification_t *cb,
    void *cbdata)
{
	const struct weightened_nhop *wn;
	uint32_t num_nhops;
	struct rib_cmd_info rc_new;

	rc_new = *rc;
	switch (rc->rc_cmd) {
	case RTM_ADD:
		if (!NH_IS_NHGRP(rc->rc_nh_new))
			return;
		wn = nhgrp_get_nhops((struct nhgrp_object *)rc->rc_nh_new, &num_nhops);
		for (uint32_t i = 0; i < num_nhops; i++) {
			notify_add(&rc_new, &wn[i], cb, cbdata);
		}
		break;
	case RTM_DELETE:
		if (!NH_IS_NHGRP(rc->rc_nh_old))
			return;
		wn = nhgrp_get_nhops((struct nhgrp_object *)rc->rc_nh_old, &num_nhops);
		for (uint32_t i = 0; i < num_nhops; i++) {
			notify_del(&rc_new, &wn[i], cb, cbdata);
		}
		break;
	case RTM_CHANGE:
		if (!NH_IS_NHGRP(rc->rc_nh_old) && !NH_IS_NHGRP(rc->rc_nh_new))
			return;
		decompose_change_notification(rc, cb, cbdata);
		break;
	}
}
#endif

#ifdef INET
/*
 * Checks if the found key in the trie contains (<=) a prefix covering
 *  @paddr/@plen.
 * Returns the most specific rtentry matching the condition or NULL.
 */
static struct rtentry *
get_inet_parent_prefix(uint32_t fibnum, struct in_addr addr, int plen)
{
	struct route_nhop_data rnd;
	struct rtentry *rt;
	struct in_addr addr4;
	uint32_t scopeid;
	int parent_plen;
	struct radix_node *rn;

	rt = fib4_lookup_rt(fibnum, addr, 0, NHR_UNLOCKED, &rnd);
	if (rt == NULL)
		return (NULL);

	rt_get_inet_prefix_plen(rt, &addr4, &parent_plen, &scopeid);
	if (parent_plen <= plen)
		return (rt);

	/*
	 * There can be multiple prefixes associated with the found key:
	 * 10.0.0.0 -> 10.0.0.0/24, 10.0.0.0/23, 10.0.0.0/22, etc.
	 * All such prefixes are linked via rn_dupedkey, from most specific
	 *  to least specific. Iterate over them to check if any of these
	 *  prefixes are wider than desired plen.
	 */
	rn = (struct radix_node *)rt;
	while ((rn = rn_nextprefix(rn)) != NULL) {
		rt = RNTORT(rn);
		rt_get_inet_prefix_plen(rt, &addr4, &parent_plen, &scopeid);
		if (parent_plen <= plen)
			return (rt);
	}

	return (NULL);
}

/*
 * Returns the most specific prefix containing (>) @paddr/plen.
 */
struct rtentry *
rt_get_inet_parent(uint32_t fibnum, struct in_addr addr, int plen)
{
	struct in_addr lookup_addr = { .s_addr = INADDR_BROADCAST };
	struct in_addr addr4 = addr;
	struct in_addr mask4;
	struct rtentry *rt;

	while (plen-- > 0) {
		/* Calculate wider mask & new key to lookup */
		mask4.s_addr = htonl(plen ? ~((1 << (32 - plen)) - 1) : 0);
		addr4.s_addr = htonl(ntohl(addr4.s_addr) & ntohl(mask4.s_addr));
		if (addr4.s_addr == lookup_addr.s_addr) {
			/* Skip lookup if the key is the same */
			continue;
		}
		lookup_addr = addr4;

		rt = get_inet_parent_prefix(fibnum, lookup_addr, plen);
		if (rt != NULL)
			return (rt);
	}

	return (NULL);
}
#endif

#ifdef INET6
/*
 * Checks if the found key in the trie contains (<=) a prefix covering
 *  @paddr/@plen.
 * Returns the most specific rtentry matching the condition or NULL.
 */
static struct rtentry *
get_inet6_parent_prefix(uint32_t fibnum, const struct in6_addr *paddr, int plen)
{
	struct route_nhop_data rnd;
	struct rtentry *rt;
	struct in6_addr addr6;
	uint32_t scopeid;
	int parent_plen;
	struct radix_node *rn;

	rt = fib6_lookup_rt(fibnum, paddr, 0, NHR_UNLOCKED, &rnd);
	if (rt == NULL)
		return (NULL);

	rt_get_inet6_prefix_plen(rt, &addr6, &parent_plen, &scopeid);
	if (parent_plen <= plen)
		return (rt);

	/*
	 * There can be multiple prefixes associated with the found key:
	 * 2001:db8:1::/64 -> 2001:db8:1::/56, 2001:db8:1::/48, etc.
	 * All such prefixes are linked via rn_dupedkey, from most specific
	 *  to least specific. Iterate over them to check if any of these
	 *  prefixes are wider than desired plen.
	 */
	rn = (struct radix_node *)rt;
	while ((rn = rn_nextprefix(rn)) != NULL) {
		rt = RNTORT(rn);
		rt_get_inet6_prefix_plen(rt, &addr6, &parent_plen, &scopeid);
		if (parent_plen <= plen)
			return (rt);
	}

	return (NULL);
}

void
ip6_writemask(struct in6_addr *addr6, uint8_t mask)
{
	uint32_t *cp;

	for (cp = (uint32_t *)addr6; mask >= 32; mask -= 32)
		*cp++ = 0xFFFFFFFF;
	if (mask > 0)
		*cp = htonl(mask ? ~((1 << (32 - mask)) - 1) : 0);
}

/*
 * Returns the most specific prefix containing (>) @paddr/plen.
 */
struct rtentry *
rt_get_inet6_parent(uint32_t fibnum, const struct in6_addr *paddr, int plen)
{
	struct in6_addr lookup_addr = in6mask128;
	struct in6_addr addr6 = *paddr;
	struct in6_addr mask6;
	struct rtentry *rt;

	while (plen-- > 0) {
		/* Calculate wider mask & new key to lookup */
		ip6_writemask(&mask6, plen);
		IN6_MASK_ADDR(&addr6, &mask6);
		if (IN6_ARE_ADDR_EQUAL(&addr6, &lookup_addr)) {
			/* Skip lookup if the key is the same */
			continue;
		}
		lookup_addr = addr6;

		rt = get_inet6_parent_prefix(fibnum, &lookup_addr, plen);
		if (rt != NULL)
			return (rt);
	}

	return (NULL);
}
#endif

/*
 * Prints rtentry @rt data in the provided @buf.
 * Example: rt/192.168.0.0/24
 */
char *
rt_print_buf(const struct rtentry *rt, char *buf, size_t bufsize)
{
#if defined(INET) || defined(INET6)
	char abuf[INET6_ADDRSTRLEN];
	uint32_t scopeid;
	int plen;
#endif

	switch (rt_get_family(rt)) {
#ifdef INET
	case AF_INET:
		{
			struct in_addr addr4;
			rt_get_inet_prefix_plen(rt, &addr4, &plen, &scopeid);
			inet_ntop(AF_INET, &addr4, abuf, sizeof(abuf));
			snprintf(buf, bufsize, "rt/%s/%d", abuf, plen);
		}
		break;
#endif
#ifdef INET6
	case AF_INET6:
		{
			struct in6_addr addr6;
			rt_get_inet6_prefix_plen(rt, &addr6, &plen, &scopeid);
			inet_ntop(AF_INET6, &addr6, abuf, sizeof(abuf));
			snprintf(buf, bufsize, "rt/%s/%d", abuf, plen);
		}
		break;
#endif
	default:
		snprintf(buf, bufsize, "rt/unknown_af#%d", rt_get_family(rt));
		break;
	}

	return (buf);
}

const char *
rib_print_cmd(int rib_cmd)
{
	switch (rib_cmd) {
	case RTM_ADD:
		return ("RTM_ADD");
	case RTM_CHANGE:
		return ("RTM_CHANGE");
	case RTM_DELETE:
		return ("RTM_DELETE");
	case RTM_GET:
		return ("RTM_GET");
	}

	return ("UNKNOWN");
}