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linux/net/ipv4/fib_semantics.c
Ido Schimmel 1fa3314c14 ipv4: Centralize TOS matching 
The TOS field in the IPv4 flow information structure ('flowi4_tos') is
matched by the kernel against the TOS selector in IPv4 rules and routes.
The field is initialized differently by different call sites. Some treat
it as DSCP (RFC 2474) and initialize all six DSCP bits, some treat it as
RFC 1349 TOS and initialize it using RT_TOS() and some treat it as RFC
791 TOS and initialize it using IPTOS_RT_MASK.

What is common to all these call sites is that they all initialize the
lower three DSCP bits, which fits the TOS definition in the initial IPv4
specification (RFC 791).

Therefore, the kernel only allows configuring IPv4 FIB rules that match
on the lower three DSCP bits which are always guaranteed to be
initialized by all call sites:

 # ip -4 rule add tos 0x1c table 100
 # ip -4 rule add tos 0x3c table 100
 Error: Invalid tos.

While this works, it is unlikely to be very useful. RFC 791 that
initially defined the TOS and IP precedence fields was updated by RFC
2474 over twenty five years ago where these fields were replaced by a
single six bits DSCP field.

Extending FIB rules to match on DSCP can be done by adding a new DSCP
selector while maintaining the existing semantics of the TOS selector
for applications that rely on that.

A prerequisite for allowing FIB rules to match on DSCP is to adjust all
the call sites to initialize the high order DSCP bits and remove their
masking along the path to the core where the field is matched on.

However, making this change alone will result in a behavior change. For
example, a forwarded IPv4 packet with a DS field of 0xfc will no longer
match a FIB rule that was configured with 'tos 0x1c'.

This behavior change can be avoided by masking the upper three DSCP bits
in 'flowi4_tos' before comparing it against the TOS selectors in FIB
rules and routes.

Implement the above by adding a new function that checks whether a given
DSCP value matches the one specified in the IPv4 flow information
structure and invoke it from the three places that currently match on
'flowi4_tos'.

Use RT_TOS() for the masking of 'flowi4_tos' instead of IPTOS_RT_MASK
since the latter is not uAPI and we should be able to remove it at some
point.

Include <linux/ip.h> in <linux/in_route.h> since the former defines
IPTOS_TOS_MASK which is used in the definition of RT_TOS() in
<linux/in_route.h>.

No regressions in FIB tests:

 # ./fib_tests.sh
 [...]
 Tests passed: 218
 Tests failed:   0

And FIB rule tests:

 # ./fib_rule_tests.sh
 [...]
 Tests passed: 116
 Tests failed:   0

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2024-08-20 14:57:08 +02:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* IPv4 Forwarding Information Base: semantics.
*
* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
*/
#include <linux/uaccess.h>
#include <linux/bitops.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/jiffies.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/errno.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/inetdevice.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/proc_fs.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/netlink.h>
#include <linux/hash.h>
#include <linux/nospec.h>
#include <net/arp.h>
#include <net/inet_dscp.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <net/route.h>
#include <net/tcp.h>
#include <net/sock.h>
#include <net/ip_fib.h>
#include <net/ip6_fib.h>
#include <net/nexthop.h>
#include <net/netlink.h>
#include <net/rtnh.h>
#include <net/lwtunnel.h>
#include <net/fib_notifier.h>
#include <net/addrconf.h>
#include "fib_lookup.h"
static DEFINE_SPINLOCK(fib_info_lock);
static struct hlist_head *fib_info_hash;
static struct hlist_head *fib_info_laddrhash;
static unsigned int fib_info_hash_size;
static unsigned int fib_info_hash_bits;
static unsigned int fib_info_cnt;
#define DEVINDEX_HASHBITS 8
#define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
/* for_nexthops and change_nexthops only used when nexthop object
* is not set in a fib_info. The logic within can reference fib_nh.
*/
#ifdef CONFIG_IP_ROUTE_MULTIPATH
#define for_nexthops(fi) { \
int nhsel; const struct fib_nh *nh; \
for (nhsel = 0, nh = (fi)->fib_nh; \
nhsel < fib_info_num_path((fi)); \
nh++, nhsel++)
#define change_nexthops(fi) { \
int nhsel; struct fib_nh *nexthop_nh; \
for (nhsel = 0, nexthop_nh = (struct fib_nh *)((fi)->fib_nh); \
nhsel < fib_info_num_path((fi)); \
nexthop_nh++, nhsel++)
#else /* CONFIG_IP_ROUTE_MULTIPATH */
/* Hope, that gcc will optimize it to get rid of dummy loop */
#define for_nexthops(fi) { \
int nhsel; const struct fib_nh *nh = (fi)->fib_nh; \
for (nhsel = 0; nhsel < 1; nhsel++)
#define change_nexthops(fi) { \
int nhsel; \
struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh); \
for (nhsel = 0; nhsel < 1; nhsel++)
#endif /* CONFIG_IP_ROUTE_MULTIPATH */
#define endfor_nexthops(fi) }
const struct fib_prop fib_props[RTN_MAX + 1] = {
[RTN_UNSPEC] = {
.error = 0,
.scope = RT_SCOPE_NOWHERE,
},
[RTN_UNICAST] = {
.error = 0,
.scope = RT_SCOPE_UNIVERSE,
},
[RTN_LOCAL] = {
.error = 0,
.scope = RT_SCOPE_HOST,
},
[RTN_BROADCAST] = {
.error = 0,
.scope = RT_SCOPE_LINK,
},
[RTN_ANYCAST] = {
.error = 0,
.scope = RT_SCOPE_LINK,
},
[RTN_MULTICAST] = {
.error = 0,
.scope = RT_SCOPE_UNIVERSE,
},
[RTN_BLACKHOLE] = {
.error = -EINVAL,
.scope = RT_SCOPE_UNIVERSE,
},
[RTN_UNREACHABLE] = {
.error = -EHOSTUNREACH,
.scope = RT_SCOPE_UNIVERSE,
},
[RTN_PROHIBIT] = {
.error = -EACCES,
.scope = RT_SCOPE_UNIVERSE,
},
[RTN_THROW] = {
.error = -EAGAIN,
.scope = RT_SCOPE_UNIVERSE,
},
[RTN_NAT] = {
.error = -EINVAL,
.scope = RT_SCOPE_NOWHERE,
},
[RTN_XRESOLVE] = {
.error = -EINVAL,
.scope = RT_SCOPE_NOWHERE,
},
};
static void rt_fibinfo_free(struct rtable __rcu **rtp)
{
struct rtable *rt = rcu_dereference_protected(*rtp, 1);
if (!rt)
return;
/* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
* because we waited an RCU grace period before calling
* free_fib_info_rcu()
*/
dst_dev_put(&rt->dst);
dst_release_immediate(&rt->dst);
}
static void free_nh_exceptions(struct fib_nh_common *nhc)
{
struct fnhe_hash_bucket *hash;
int i;
hash = rcu_dereference_protected(nhc->nhc_exceptions, 1);
if (!hash)
return;
for (i = 0; i < FNHE_HASH_SIZE; i++) {
struct fib_nh_exception *fnhe;
fnhe = rcu_dereference_protected(hash[i].chain, 1);
while (fnhe) {
struct fib_nh_exception *next;
next = rcu_dereference_protected(fnhe->fnhe_next, 1);
rt_fibinfo_free(&fnhe->fnhe_rth_input);
rt_fibinfo_free(&fnhe->fnhe_rth_output);
kfree(fnhe);
fnhe = next;
}
}
kfree(hash);
}
static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
{
int cpu;
if (!rtp)
return;
for_each_possible_cpu(cpu) {
struct rtable *rt;
rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
if (rt) {
dst_dev_put(&rt->dst);
dst_release_immediate(&rt->dst);
}
}
free_percpu(rtp);
}
void fib_nh_common_release(struct fib_nh_common *nhc)
{
netdev_put(nhc->nhc_dev, &nhc->nhc_dev_tracker);
lwtstate_put(nhc->nhc_lwtstate);
rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
rt_fibinfo_free(&nhc->nhc_rth_input);
free_nh_exceptions(nhc);
}
EXPORT_SYMBOL_GPL(fib_nh_common_release);
void fib_nh_release(struct net *net, struct fib_nh *fib_nh)
{
#ifdef CONFIG_IP_ROUTE_CLASSID
if (fib_nh->nh_tclassid)
atomic_dec(&net->ipv4.fib_num_tclassid_users);
#endif
fib_nh_common_release(&fib_nh->nh_common);
}
/* Release a nexthop info record */
static void free_fib_info_rcu(struct rcu_head *head)
{
struct fib_info *fi = container_of(head, struct fib_info, rcu);
if (fi->nh) {
nexthop_put(fi->nh);
} else {
change_nexthops(fi) {
fib_nh_release(fi->fib_net, nexthop_nh);
} endfor_nexthops(fi);
}
ip_fib_metrics_put(fi->fib_metrics);
kfree(fi);
}
void free_fib_info(struct fib_info *fi)
{
if (fi->fib_dead == 0) {
pr_warn("Freeing alive fib_info %p\n", fi);
return;
}
call_rcu_hurry(&fi->rcu, free_fib_info_rcu);
}
EXPORT_SYMBOL_GPL(free_fib_info);
void fib_release_info(struct fib_info *fi)
{
spin_lock_bh(&fib_info_lock);
if (fi && refcount_dec_and_test(&fi->fib_treeref)) {
hlist_del(&fi->fib_hash);
/* Paired with READ_ONCE() in fib_create_info(). */
WRITE_ONCE(fib_info_cnt, fib_info_cnt - 1);
if (fi->fib_prefsrc)
hlist_del(&fi->fib_lhash);
if (fi->nh) {
list_del(&fi->nh_list);
} else {
change_nexthops(fi) {
if (!nexthop_nh->fib_nh_dev)
continue;
hlist_del(&nexthop_nh->nh_hash);
} endfor_nexthops(fi)
}
/* Paired with READ_ONCE() from fib_table_lookup() */
WRITE_ONCE(fi->fib_dead, 1);
fib_info_put(fi);
}
spin_unlock_bh(&fib_info_lock);
}
static inline int nh_comp(struct fib_info *fi, struct fib_info *ofi)
{
const struct fib_nh *onh;
if (fi->nh || ofi->nh)
return nexthop_cmp(fi->nh, ofi->nh) ? 0 : -1;
if (ofi->fib_nhs == 0)
return 0;
for_nexthops(fi) {
onh = fib_info_nh(ofi, nhsel);
if (nh->fib_nh_oif != onh->fib_nh_oif ||
nh->fib_nh_gw_family != onh->fib_nh_gw_family ||
nh->fib_nh_scope != onh->fib_nh_scope ||
#ifdef CONFIG_IP_ROUTE_MULTIPATH
nh->fib_nh_weight != onh->fib_nh_weight ||
#endif
#ifdef CONFIG_IP_ROUTE_CLASSID
nh->nh_tclassid != onh->nh_tclassid ||
#endif
lwtunnel_cmp_encap(nh->fib_nh_lws, onh->fib_nh_lws) ||
((nh->fib_nh_flags ^ onh->fib_nh_flags) & ~RTNH_COMPARE_MASK))
return -1;
if (nh->fib_nh_gw_family == AF_INET &&
nh->fib_nh_gw4 != onh->fib_nh_gw4)
return -1;
if (nh->fib_nh_gw_family == AF_INET6 &&
ipv6_addr_cmp(&nh->fib_nh_gw6, &onh->fib_nh_gw6))
return -1;
} endfor_nexthops(fi);
return 0;
}
static inline unsigned int fib_devindex_hashfn(unsigned int val)
{
return hash_32(val, DEVINDEX_HASHBITS);
}
static struct hlist_head *
fib_info_devhash_bucket(const struct net_device *dev)
{
u32 val = net_hash_mix(dev_net(dev)) ^ dev->ifindex;
return &fib_info_devhash[fib_devindex_hashfn(val)];
}
static unsigned int fib_info_hashfn_1(int init_val, u8 protocol, u8 scope,
u32 prefsrc, u32 priority)
{
unsigned int val = init_val;
val ^= (protocol << 8) | scope;
val ^= prefsrc;
val ^= priority;
return val;
}
static unsigned int fib_info_hashfn_result(unsigned int val)
{
unsigned int mask = (fib_info_hash_size - 1);
return (val ^ (val >> 7) ^ (val >> 12)) & mask;
}
static inline unsigned int fib_info_hashfn(struct fib_info *fi)
{
unsigned int val;
val = fib_info_hashfn_1(fi->fib_nhs, fi->fib_protocol,
fi->fib_scope, (__force u32)fi->fib_prefsrc,
fi->fib_priority);
if (fi->nh) {
val ^= fib_devindex_hashfn(fi->nh->id);
} else {
for_nexthops(fi) {
val ^= fib_devindex_hashfn(nh->fib_nh_oif);
} endfor_nexthops(fi)
}
return fib_info_hashfn_result(val);
}
/* no metrics, only nexthop id */
static struct fib_info *fib_find_info_nh(struct net *net,
const struct fib_config *cfg)
{
struct hlist_head *head;
struct fib_info *fi;
unsigned int hash;
hash = fib_info_hashfn_1(fib_devindex_hashfn(cfg->fc_nh_id),
cfg->fc_protocol, cfg->fc_scope,
(__force u32)cfg->fc_prefsrc,
cfg->fc_priority);
hash = fib_info_hashfn_result(hash);
head = &fib_info_hash[hash];
hlist_for_each_entry(fi, head, fib_hash) {
if (!net_eq(fi->fib_net, net))
continue;
if (!fi->nh || fi->nh->id != cfg->fc_nh_id)
continue;
if (cfg->fc_protocol == fi->fib_protocol &&
cfg->fc_scope == fi->fib_scope &&
cfg->fc_prefsrc == fi->fib_prefsrc &&
cfg->fc_priority == fi->fib_priority &&
cfg->fc_type == fi->fib_type &&
cfg->fc_table == fi->fib_tb_id &&
!((cfg->fc_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK))
return fi;
}
return NULL;
}
static struct fib_info *fib_find_info(struct fib_info *nfi)
{
struct hlist_head *head;
struct fib_info *fi;
unsigned int hash;
hash = fib_info_hashfn(nfi);
head = &fib_info_hash[hash];
hlist_for_each_entry(fi, head, fib_hash) {
if (!net_eq(fi->fib_net, nfi->fib_net))
continue;
if (fi->fib_nhs != nfi->fib_nhs)
continue;
if (nfi->fib_protocol == fi->fib_protocol &&
nfi->fib_scope == fi->fib_scope &&
nfi->fib_prefsrc == fi->fib_prefsrc &&
nfi->fib_priority == fi->fib_priority &&
nfi->fib_type == fi->fib_type &&
nfi->fib_tb_id == fi->fib_tb_id &&
memcmp(nfi->fib_metrics, fi->fib_metrics,
sizeof(u32) * RTAX_MAX) == 0 &&
!((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK) &&
nh_comp(fi, nfi) == 0)
return fi;
}
return NULL;
}
/* Check, that the gateway is already configured.
* Used only by redirect accept routine.
*/
int ip_fib_check_default(__be32 gw, struct net_device *dev)
{
struct hlist_head *head;
struct fib_nh *nh;
spin_lock(&fib_info_lock);
head = fib_info_devhash_bucket(dev);
hlist_for_each_entry(nh, head, nh_hash) {
if (nh->fib_nh_dev == dev &&
nh->fib_nh_gw4 == gw &&
!(nh->fib_nh_flags & RTNH_F_DEAD)) {
spin_unlock(&fib_info_lock);
return 0;
}
}
spin_unlock(&fib_info_lock);
return -1;
}
size_t fib_nlmsg_size(struct fib_info *fi)
{
size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
+ nla_total_size(4) /* RTA_TABLE */
+ nla_total_size(4) /* RTA_DST */
+ nla_total_size(4) /* RTA_PRIORITY */
+ nla_total_size(4) /* RTA_PREFSRC */
+ nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
unsigned int nhs = fib_info_num_path(fi);
/* space for nested metrics */
payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
if (fi->nh)
payload += nla_total_size(4); /* RTA_NH_ID */
if (nhs) {
size_t nh_encapsize = 0;
/* Also handles the special case nhs == 1 */
/* each nexthop is packed in an attribute */
size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
unsigned int i;
/* may contain flow and gateway attribute */
nhsize += 2 * nla_total_size(4);
/* grab encap info */
for (i = 0; i < fib_info_num_path(fi); i++) {
struct fib_nh_common *nhc = fib_info_nhc(fi, i);
if (nhc->nhc_lwtstate) {
/* RTA_ENCAP_TYPE */
nh_encapsize += lwtunnel_get_encap_size(
nhc->nhc_lwtstate);
/* RTA_ENCAP */
nh_encapsize += nla_total_size(2);
}
}
/* all nexthops are packed in a nested attribute */
payload += nla_total_size((nhs * nhsize) + nh_encapsize);
}
return payload;
}
void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
int dst_len, u32 tb_id, const struct nl_info *info,
unsigned int nlm_flags)
{
struct fib_rt_info fri;
struct sk_buff *skb;
u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
int err = -ENOBUFS;
skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
if (!skb)
goto errout;
fri.fi = fa->fa_info;
fri.tb_id = tb_id;
fri.dst = key;
fri.dst_len = dst_len;
fri.dscp = fa->fa_dscp;
fri.type = fa->fa_type;
fri.offload = READ_ONCE(fa->offload);
fri.trap = READ_ONCE(fa->trap);
fri.offload_failed = READ_ONCE(fa->offload_failed);
err = fib_dump_info(skb, info->portid, seq, event, &fri, nlm_flags);
if (err < 0) {
/* -EMSGSIZE implies BUG in fib_nlmsg_size() */
WARN_ON(err == -EMSGSIZE);
kfree_skb(skb);
goto errout;
}
rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
info->nlh, GFP_KERNEL);
return;
errout:
if (err < 0)
rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
}
static int fib_detect_death(struct fib_info *fi, int order,
struct fib_info **last_resort, int *last_idx,
int dflt)
{
const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
struct neighbour *n;
int state = NUD_NONE;
if (likely(nhc->nhc_gw_family == AF_INET))
n = neigh_lookup(&arp_tbl, &nhc->nhc_gw.ipv4, nhc->nhc_dev);
else if (nhc->nhc_gw_family == AF_INET6)
n = neigh_lookup(ipv6_stub->nd_tbl, &nhc->nhc_gw.ipv6,
nhc->nhc_dev);
else
n = NULL;
if (n) {
state = READ_ONCE(n->nud_state);
neigh_release(n);
} else {
return 0;
}
if (state == NUD_REACHABLE)
return 0;
if ((state & NUD_VALID) && order != dflt)
return 0;
if ((state & NUD_VALID) ||
(*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {
*last_resort = fi;
*last_idx = order;
}
return 1;
}
int fib_nh_common_init(struct net *net, struct fib_nh_common *nhc,
struct nlattr *encap, u16 encap_type,
void *cfg, gfp_t gfp_flags,
struct netlink_ext_ack *extack)
{
int err;
nhc->nhc_pcpu_rth_output = alloc_percpu_gfp(struct rtable __rcu *,
gfp_flags);
if (!nhc->nhc_pcpu_rth_output)
return -ENOMEM;
if (encap) {
struct lwtunnel_state *lwtstate;
if (encap_type == LWTUNNEL_ENCAP_NONE) {
NL_SET_ERR_MSG(extack, "LWT encap type not specified");
err = -EINVAL;
goto lwt_failure;
}
err = lwtunnel_build_state(net, encap_type, encap,
nhc->nhc_family, cfg, &lwtstate,
extack);
if (err)
goto lwt_failure;
nhc->nhc_lwtstate = lwtstate_get(lwtstate);
}
return 0;
lwt_failure:
rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
nhc->nhc_pcpu_rth_output = NULL;
return err;
}
EXPORT_SYMBOL_GPL(fib_nh_common_init);
int fib_nh_init(struct net *net, struct fib_nh *nh,
struct fib_config *cfg, int nh_weight,
struct netlink_ext_ack *extack)
{
int err;
nh->fib_nh_family = AF_INET;
err = fib_nh_common_init(net, &nh->nh_common, cfg->fc_encap,
cfg->fc_encap_type, cfg, GFP_KERNEL, extack);
if (err)
return err;
nh->fib_nh_oif = cfg->fc_oif;
nh->fib_nh_gw_family = cfg->fc_gw_family;
if (cfg->fc_gw_family == AF_INET)
nh->fib_nh_gw4 = cfg->fc_gw4;
else if (cfg->fc_gw_family == AF_INET6)
nh->fib_nh_gw6 = cfg->fc_gw6;
nh->fib_nh_flags = cfg->fc_flags;
#ifdef CONFIG_IP_ROUTE_CLASSID
nh->nh_tclassid = cfg->fc_flow;
if (nh->nh_tclassid)
atomic_inc(&net->ipv4.fib_num_tclassid_users);
#endif
#ifdef CONFIG_IP_ROUTE_MULTIPATH
nh->fib_nh_weight = nh_weight;
#endif
return 0;
}
#ifdef CONFIG_IP_ROUTE_MULTIPATH
static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining,
struct netlink_ext_ack *extack)
{
int nhs = 0;
while (rtnh_ok(rtnh, remaining)) {
nhs++;
rtnh = rtnh_next(rtnh, &remaining);
}
/* leftover implies invalid nexthop configuration, discard it */
if (remaining > 0) {
NL_SET_ERR_MSG(extack,
"Invalid nexthop configuration - extra data after nexthops");
nhs = 0;
}
return nhs;
}
static int fib_gw_from_attr(__be32 *gw, struct nlattr *nla,
struct netlink_ext_ack *extack)
{
if (nla_len(nla) < sizeof(*gw)) {
NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY");
return -EINVAL;
}
*gw = nla_get_in_addr(nla);
return 0;
}
/* only called when fib_nh is integrated into fib_info */
static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
int remaining, struct fib_config *cfg,
struct netlink_ext_ack *extack)
{
struct net *net = fi->fib_net;
struct fib_config fib_cfg;
struct fib_nh *nh;
int ret;
change_nexthops(fi) {
int attrlen;
memset(&fib_cfg, 0, sizeof(fib_cfg));
if (!rtnh_ok(rtnh, remaining)) {
NL_SET_ERR_MSG(extack,
"Invalid nexthop configuration - extra data after nexthop");
return -EINVAL;
}
if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
NL_SET_ERR_MSG(extack,
"Invalid flags for nexthop - can not contain DEAD or LINKDOWN");
return -EINVAL;
}
fib_cfg.fc_flags = (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
fib_cfg.fc_oif = rtnh->rtnh_ifindex;
attrlen = rtnh_attrlen(rtnh);
if (attrlen > 0) {
struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
nla = nla_find(attrs, attrlen, RTA_GATEWAY);
nlav = nla_find(attrs, attrlen, RTA_VIA);
if (nla && nlav) {
NL_SET_ERR_MSG(extack,
"Nexthop configuration can not contain both GATEWAY and VIA");
return -EINVAL;
}
if (nla) {
ret = fib_gw_from_attr(&fib_cfg.fc_gw4, nla,
extack);
if (ret)
goto errout;
if (fib_cfg.fc_gw4)
fib_cfg.fc_gw_family = AF_INET;
} else if (nlav) {
ret = fib_gw_from_via(&fib_cfg, nlav, extack);
if (ret)
goto errout;
}
nla = nla_find(attrs, attrlen, RTA_FLOW);
if (nla) {
if (nla_len(nla) < sizeof(u32)) {
NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
return -EINVAL;
}
fib_cfg.fc_flow = nla_get_u32(nla);
}
fib_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
/* RTA_ENCAP_TYPE length checked in
* lwtunnel_valid_encap_type_attr
*/
nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
if (nla)
fib_cfg.fc_encap_type = nla_get_u16(nla);
}
ret = fib_nh_init(net, nexthop_nh, &fib_cfg,
rtnh->rtnh_hops + 1, extack);
if (ret)
goto errout;
rtnh = rtnh_next(rtnh, &remaining);
} endfor_nexthops(fi);
ret = -EINVAL;
nh = fib_info_nh(fi, 0);
if (cfg->fc_oif && nh->fib_nh_oif != cfg->fc_oif) {
NL_SET_ERR_MSG(extack,
"Nexthop device index does not match RTA_OIF");
goto errout;
}
if (cfg->fc_gw_family) {
if (cfg->fc_gw_family != nh->fib_nh_gw_family ||
(cfg->fc_gw_family == AF_INET &&
nh->fib_nh_gw4 != cfg->fc_gw4) ||
(cfg->fc_gw_family == AF_INET6 &&
ipv6_addr_cmp(&nh->fib_nh_gw6, &cfg->fc_gw6))) {
NL_SET_ERR_MSG(extack,
"Nexthop gateway does not match RTA_GATEWAY or RTA_VIA");
goto errout;
}
}
#ifdef CONFIG_IP_ROUTE_CLASSID
if (cfg->fc_flow && nh->nh_tclassid != cfg->fc_flow) {
NL_SET_ERR_MSG(extack,
"Nexthop class id does not match RTA_FLOW");
goto errout;
}
#endif
ret = 0;
errout:
return ret;
}
/* only called when fib_nh is integrated into fib_info */
static void fib_rebalance(struct fib_info *fi)
{
int total;
int w;
if (fib_info_num_path(fi) < 2)
return;
total = 0;
for_nexthops(fi) {
if (nh->fib_nh_flags & RTNH_F_DEAD)
continue;
if (ip_ignore_linkdown(nh->fib_nh_dev) &&
nh->fib_nh_flags & RTNH_F_LINKDOWN)
continue;
total += nh->fib_nh_weight;
} endfor_nexthops(fi);
w = 0;
change_nexthops(fi) {
int upper_bound;
if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD) {
upper_bound = -1;
} else if (ip_ignore_linkdown(nexthop_nh->fib_nh_dev) &&
nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN) {
upper_bound = -1;
} else {
w += nexthop_nh->fib_nh_weight;
upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
total) - 1;
}
atomic_set(&nexthop_nh->fib_nh_upper_bound, upper_bound);
} endfor_nexthops(fi);
}
#else /* CONFIG_IP_ROUTE_MULTIPATH */
static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
int remaining, struct fib_config *cfg,
struct netlink_ext_ack *extack)
{
NL_SET_ERR_MSG(extack, "Multipath support not enabled in kernel");
return -EINVAL;
}
#define fib_rebalance(fi) do { } while (0)
#endif /* CONFIG_IP_ROUTE_MULTIPATH */
static int fib_encap_match(struct net *net, u16 encap_type,
struct nlattr *encap,
const struct fib_nh *nh,
const struct fib_config *cfg,
struct netlink_ext_ack *extack)
{
struct lwtunnel_state *lwtstate;
int ret, result = 0;
if (encap_type == LWTUNNEL_ENCAP_NONE)
return 0;
ret = lwtunnel_build_state(net, encap_type, encap, AF_INET,
cfg, &lwtstate, extack);
if (!ret) {
result = lwtunnel_cmp_encap(lwtstate, nh->fib_nh_lws);
lwtstate_free(lwtstate);
}
return result;
}
int fib_nh_match(struct net *net, struct fib_config *cfg, struct fib_info *fi,
struct netlink_ext_ack *extack)
{
#ifdef CONFIG_IP_ROUTE_MULTIPATH
struct rtnexthop *rtnh;
int remaining;
#endif
if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
return 1;
if (cfg->fc_nh_id) {
if (fi->nh && cfg->fc_nh_id == fi->nh->id)
return 0;
return 1;
}
if (fi->nh) {
if (cfg->fc_oif || cfg->fc_gw_family || cfg->fc_mp)
return 1;
return 0;
}
if (cfg->fc_oif || cfg->fc_gw_family) {
struct fib_nh *nh;
nh = fib_info_nh(fi, 0);
if (cfg->fc_encap) {
if (fib_encap_match(net, cfg->fc_encap_type,
cfg->fc_encap, nh, cfg, extack))
return 1;
}
#ifdef CONFIG_IP_ROUTE_CLASSID
if (cfg->fc_flow &&
cfg->fc_flow != nh->nh_tclassid)
return 1;
#endif
if ((cfg->fc_oif && cfg->fc_oif != nh->fib_nh_oif) ||
(cfg->fc_gw_family &&
cfg->fc_gw_family != nh->fib_nh_gw_family))
return 1;
if (cfg->fc_gw_family == AF_INET &&
cfg->fc_gw4 != nh->fib_nh_gw4)
return 1;
if (cfg->fc_gw_family == AF_INET6 &&
ipv6_addr_cmp(&cfg->fc_gw6, &nh->fib_nh_gw6))
return 1;
return 0;
}
#ifdef CONFIG_IP_ROUTE_MULTIPATH
if (!cfg->fc_mp)
return 0;
rtnh = cfg->fc_mp;
remaining = cfg->fc_mp_len;
for_nexthops(fi) {
int attrlen;
if (!rtnh_ok(rtnh, remaining))
return -EINVAL;
if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->fib_nh_oif)
return 1;
attrlen = rtnh_attrlen(rtnh);
if (attrlen > 0) {
struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
int err;
nla = nla_find(attrs, attrlen, RTA_GATEWAY);
nlav = nla_find(attrs, attrlen, RTA_VIA);
if (nla && nlav) {
NL_SET_ERR_MSG(extack,
"Nexthop configuration can not contain both GATEWAY and VIA");
return -EINVAL;
}
if (nla) {
__be32 gw;
err = fib_gw_from_attr(&gw, nla, extack);
if (err)
return err;
if (nh->fib_nh_gw_family != AF_INET ||
gw != nh->fib_nh_gw4)
return 1;
} else if (nlav) {
struct fib_config cfg2;
err = fib_gw_from_via(&cfg2, nlav, extack);
if (err)
return err;
switch (nh->fib_nh_gw_family) {
case AF_INET:
if (cfg2.fc_gw_family != AF_INET ||
cfg2.fc_gw4 != nh->fib_nh_gw4)
return 1;
break;
case AF_INET6:
if (cfg2.fc_gw_family != AF_INET6 ||
ipv6_addr_cmp(&cfg2.fc_gw6,
&nh->fib_nh_gw6))
return 1;
break;
}
}
#ifdef CONFIG_IP_ROUTE_CLASSID
nla = nla_find(attrs, attrlen, RTA_FLOW);
if (nla) {
if (nla_len(nla) < sizeof(u32)) {
NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
return -EINVAL;
}
if (nla_get_u32(nla) != nh->nh_tclassid)
return 1;
}
#endif
}
rtnh = rtnh_next(rtnh, &remaining);
} endfor_nexthops(fi);
#endif
return 0;
}
bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
{
struct nlattr *nla;
int remaining;
if (!cfg->fc_mx)
return true;
nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
int type = nla_type(nla);
u32 fi_val, val;
if (!type)
continue;
if (type > RTAX_MAX)
return false;
type = array_index_nospec(type, RTAX_MAX + 1);
if (type == RTAX_CC_ALGO) {
char tmp[TCP_CA_NAME_MAX];
bool ecn_ca = false;
nla_strscpy(tmp, nla, sizeof(tmp));
val = tcp_ca_get_key_by_name(tmp, &ecn_ca);
} else {
if (nla_len(nla) != sizeof(u32))
return false;
val = nla_get_u32(nla);
}
fi_val = fi->fib_metrics->metrics[type - 1];
if (type == RTAX_FEATURES)
fi_val &= ~DST_FEATURE_ECN_CA;
if (fi_val != val)
return false;
}
return true;
}
static int fib_check_nh_v6_gw(struct net *net, struct fib_nh *nh,
u32 table, struct netlink_ext_ack *extack)
{
struct fib6_config cfg = {
.fc_table = table,
.fc_flags = nh->fib_nh_flags | RTF_GATEWAY,
.fc_ifindex = nh->fib_nh_oif,
.fc_gateway = nh->fib_nh_gw6,
};
struct fib6_nh fib6_nh = {};
int err;
err = ipv6_stub->fib6_nh_init(net, &fib6_nh, &cfg, GFP_KERNEL, extack);
if (!err) {
nh->fib_nh_dev = fib6_nh.fib_nh_dev;
netdev_hold(nh->fib_nh_dev, &nh->fib_nh_dev_tracker,
GFP_KERNEL);
nh->fib_nh_oif = nh->fib_nh_dev->ifindex;
nh->fib_nh_scope = RT_SCOPE_LINK;
ipv6_stub->fib6_nh_release(&fib6_nh);
}
return err;
}
/*
* Picture
* -------
*
* Semantics of nexthop is very messy by historical reasons.
* We have to take into account, that:
* a) gateway can be actually local interface address,
* so that gatewayed route is direct.
* b) gateway must be on-link address, possibly
* described not by an ifaddr, but also by a direct route.
* c) If both gateway and interface are specified, they should not
* contradict.
* d) If we use tunnel routes, gateway could be not on-link.
*
* Attempt to reconcile all of these (alas, self-contradictory) conditions
* results in pretty ugly and hairy code with obscure logic.
*
* I chose to generalized it instead, so that the size
* of code does not increase practically, but it becomes
* much more general.
* Every prefix is assigned a "scope" value: "host" is local address,
* "link" is direct route,
* [ ... "site" ... "interior" ... ]
* and "universe" is true gateway route with global meaning.
*
* Every prefix refers to a set of "nexthop"s (gw, oif),
* where gw must have narrower scope. This recursion stops
* when gw has LOCAL scope or if "nexthop" is declared ONLINK,
* which means that gw is forced to be on link.
*
* Code is still hairy, but now it is apparently logically
* consistent and very flexible. F.e. as by-product it allows
* to co-exists in peace independent exterior and interior
* routing processes.
*
* Normally it looks as following.
*
* {universe prefix} -> (gw, oif) [scope link]
* |
* |-> {link prefix} -> (gw, oif) [scope local]
* |
* |-> {local prefix} (terminal node)
*/
static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
u8 scope, struct netlink_ext_ack *extack)
{
struct net_device *dev;
struct fib_result res;
int err = 0;
if (nh->fib_nh_flags & RTNH_F_ONLINK) {
unsigned int addr_type;
if (scope >= RT_SCOPE_LINK) {
NL_SET_ERR_MSG(extack, "Nexthop has invalid scope");
return -EINVAL;
}
dev = __dev_get_by_index(net, nh->fib_nh_oif);
if (!dev) {
NL_SET_ERR_MSG(extack, "Nexthop device required for onlink");
return -ENODEV;
}
if (!(dev->flags & IFF_UP)) {
NL_SET_ERR_MSG(extack, "Nexthop device is not up");
return -ENETDOWN;
}
addr_type = inet_addr_type_dev_table(net, dev, nh->fib_nh_gw4);
if (addr_type != RTN_UNICAST) {
NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
return -EINVAL;
}
if (!netif_carrier_ok(dev))
nh->fib_nh_flags |= RTNH_F_LINKDOWN;
nh->fib_nh_dev = dev;
netdev_hold(dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
nh->fib_nh_scope = RT_SCOPE_LINK;
return 0;
}
rcu_read_lock();
{
struct fib_table *tbl = NULL;
struct flowi4 fl4 = {
.daddr = nh->fib_nh_gw4,
.flowi4_scope = scope + 1,
.flowi4_oif = nh->fib_nh_oif,
.flowi4_iif = LOOPBACK_IFINDEX,
};
/* It is not necessary, but requires a bit of thinking */
if (fl4.flowi4_scope < RT_SCOPE_LINK)
fl4.flowi4_scope = RT_SCOPE_LINK;
if (table && table != RT_TABLE_MAIN)
tbl = fib_get_table(net, table);
if (tbl)
err = fib_table_lookup(tbl, &fl4, &res,
FIB_LOOKUP_IGNORE_LINKSTATE |
FIB_LOOKUP_NOREF);
/* on error or if no table given do full lookup. This
* is needed for example when nexthops are in the local
* table rather than the given table
*/
if (!tbl || err) {
err = fib_lookup(net, &fl4, &res,
FIB_LOOKUP_IGNORE_LINKSTATE);
}
if (err) {
NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
goto out;
}
}
err = -EINVAL;
if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
goto out;
}
nh->fib_nh_scope = res.scope;
nh->fib_nh_oif = FIB_RES_OIF(res);
nh->fib_nh_dev = dev = FIB_RES_DEV(res);
if (!dev) {
NL_SET_ERR_MSG(extack,
"No egress device for nexthop gateway");
goto out;
}
netdev_hold(dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
if (!netif_carrier_ok(dev))
nh->fib_nh_flags |= RTNH_F_LINKDOWN;
err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
out:
rcu_read_unlock();
return err;
}
static int fib_check_nh_nongw(struct net *net, struct fib_nh *nh,
struct netlink_ext_ack *extack)
{
struct in_device *in_dev;
int err;
if (nh->fib_nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
NL_SET_ERR_MSG(extack,
"Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
return -EINVAL;
}
rcu_read_lock();
err = -ENODEV;
in_dev = inetdev_by_index(net, nh->fib_nh_oif);
if (!in_dev)
goto out;
err = -ENETDOWN;
if (!(in_dev->dev->flags & IFF_UP)) {
NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
goto out;
}
nh->fib_nh_dev = in_dev->dev;
netdev_hold(nh->fib_nh_dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
nh->fib_nh_scope = RT_SCOPE_HOST;
if (!netif_carrier_ok(nh->fib_nh_dev))
nh->fib_nh_flags |= RTNH_F_LINKDOWN;
err = 0;
out:
rcu_read_unlock();
return err;
}
int fib_check_nh(struct net *net, struct fib_nh *nh, u32 table, u8 scope,
struct netlink_ext_ack *extack)
{
int err;
if (nh->fib_nh_gw_family == AF_INET)
err = fib_check_nh_v4_gw(net, nh, table, scope, extack);
else if (nh->fib_nh_gw_family == AF_INET6)
err = fib_check_nh_v6_gw(net, nh, table, extack);
else
err = fib_check_nh_nongw(net, nh, extack);
return err;
}
static struct hlist_head *
fib_info_laddrhash_bucket(const struct net *net, __be32 val)
{
u32 slot = hash_32(net_hash_mix(net) ^ (__force u32)val,
fib_info_hash_bits);
return &fib_info_laddrhash[slot];
}
static void fib_info_hash_move(struct hlist_head *new_info_hash,
struct hlist_head *new_laddrhash,
unsigned int new_size)
{
struct hlist_head *old_info_hash, *old_laddrhash;
unsigned int old_size = fib_info_hash_size;
unsigned int i;
spin_lock_bh(&fib_info_lock);
old_info_hash = fib_info_hash;
old_laddrhash = fib_info_laddrhash;
fib_info_hash_size = new_size;
fib_info_hash_bits = ilog2(new_size);
for (i = 0; i < old_size; i++) {
struct hlist_head *head = &fib_info_hash[i];
struct hlist_node *n;
struct fib_info *fi;
hlist_for_each_entry_safe(fi, n, head, fib_hash) {
struct hlist_head *dest;
unsigned int new_hash;
new_hash = fib_info_hashfn(fi);
dest = &new_info_hash[new_hash];
hlist_add_head(&fi->fib_hash, dest);
}
}
fib_info_hash = new_info_hash;
fib_info_laddrhash = new_laddrhash;
for (i = 0; i < old_size; i++) {
struct hlist_head *lhead = &old_laddrhash[i];
struct hlist_node *n;
struct fib_info *fi;
hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
struct hlist_head *ldest;
ldest = fib_info_laddrhash_bucket(fi->fib_net,
fi->fib_prefsrc);
hlist_add_head(&fi->fib_lhash, ldest);
}
}
spin_unlock_bh(&fib_info_lock);
kvfree(old_info_hash);
kvfree(old_laddrhash);
}
__be32 fib_info_update_nhc_saddr(struct net *net, struct fib_nh_common *nhc,
unsigned char scope)
{
struct fib_nh *nh;
__be32 saddr;
if (nhc->nhc_family != AF_INET)
return inet_select_addr(nhc->nhc_dev, 0, scope);
nh = container_of(nhc, struct fib_nh, nh_common);
saddr = inet_select_addr(nh->fib_nh_dev, nh->fib_nh_gw4, scope);
WRITE_ONCE(nh->nh_saddr, saddr);
WRITE_ONCE(nh->nh_saddr_genid, atomic_read(&net->ipv4.dev_addr_genid));
return saddr;
}
__be32 fib_result_prefsrc(struct net *net, struct fib_result *res)
{
struct fib_nh_common *nhc = res->nhc;
if (res->fi->fib_prefsrc)
return res->fi->fib_prefsrc;
if (nhc->nhc_family == AF_INET) {
struct fib_nh *nh;
nh = container_of(nhc, struct fib_nh, nh_common);
if (READ_ONCE(nh->nh_saddr_genid) ==
atomic_read(&net->ipv4.dev_addr_genid))
return READ_ONCE(nh->nh_saddr);
}
return fib_info_update_nhc_saddr(net, nhc, res->fi->fib_scope);
}
static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
{
if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
fib_prefsrc != cfg->fc_dst) {
u32 tb_id = cfg->fc_table;
int rc;
if (tb_id == RT_TABLE_MAIN)
tb_id = RT_TABLE_LOCAL;
rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
fib_prefsrc, tb_id);
if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
fib_prefsrc, RT_TABLE_LOCAL);
}
if (rc != RTN_LOCAL)
return false;
}
return true;
}
struct fib_info *fib_create_info(struct fib_config *cfg,
struct netlink_ext_ack *extack)
{
int err;
struct fib_info *fi = NULL;
struct nexthop *nh = NULL;
struct fib_info *ofi;
int nhs = 1;
struct net *net = cfg->fc_nlinfo.nl_net;
if (cfg->fc_type > RTN_MAX)
goto err_inval;
/* Fast check to catch the most weird cases */
if (fib_props[cfg->fc_type].scope > cfg->fc_scope) {
NL_SET_ERR_MSG(extack, "Invalid scope");
goto err_inval;
}
if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
NL_SET_ERR_MSG(extack,
"Invalid rtm_flags - can not contain DEAD or LINKDOWN");
goto err_inval;
}
if (cfg->fc_nh_id) {
if (!cfg->fc_mx) {
fi = fib_find_info_nh(net, cfg);
if (fi) {
refcount_inc(&fi->fib_treeref);
return fi;
}
}
nh = nexthop_find_by_id(net, cfg->fc_nh_id);
if (!nh) {
NL_SET_ERR_MSG(extack, "Nexthop id does not exist");
goto err_inval;
}
nhs = 0;
}
#ifdef CONFIG_IP_ROUTE_MULTIPATH
if (cfg->fc_mp) {
nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len, extack);
if (nhs == 0)
goto err_inval;
}
#endif
err = -ENOBUFS;
/* Paired with WRITE_ONCE() in fib_release_info() */
if (READ_ONCE(fib_info_cnt) >= fib_info_hash_size) {
unsigned int new_size = fib_info_hash_size << 1;
struct hlist_head *new_info_hash;
struct hlist_head *new_laddrhash;
size_t bytes;
if (!new_size)
new_size = 16;
bytes = (size_t)new_size * sizeof(struct hlist_head *);
new_info_hash = kvzalloc(bytes, GFP_KERNEL);
new_laddrhash = kvzalloc(bytes, GFP_KERNEL);
if (!new_info_hash || !new_laddrhash) {
kvfree(new_info_hash);
kvfree(new_laddrhash);
} else {
fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
}
if (!fib_info_hash_size)
goto failure;
}
fi = kzalloc(struct_size(fi, fib_nh, nhs), GFP_KERNEL);
if (!fi)
goto failure;
fi->fib_metrics = ip_fib_metrics_init(cfg->fc_mx, cfg->fc_mx_len, extack);
if (IS_ERR(fi->fib_metrics)) {
err = PTR_ERR(fi->fib_metrics);
kfree(fi);
return ERR_PTR(err);
}
fi->fib_net = net;
fi->fib_protocol = cfg->fc_protocol;
fi->fib_scope = cfg->fc_scope;
fi->fib_flags = cfg->fc_flags;
fi->fib_priority = cfg->fc_priority;
fi->fib_prefsrc = cfg->fc_prefsrc;
fi->fib_type = cfg->fc_type;
fi->fib_tb_id = cfg->fc_table;
fi->fib_nhs = nhs;
if (nh) {
if (!nexthop_get(nh)) {
NL_SET_ERR_MSG(extack, "Nexthop has been deleted");
err = -EINVAL;
} else {
err = 0;
fi->nh = nh;
}
} else {
change_nexthops(fi) {
nexthop_nh->nh_parent = fi;
} endfor_nexthops(fi)
if (cfg->fc_mp)
err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg,
extack);
else
err = fib_nh_init(net, fi->fib_nh, cfg, 1, extack);
}
if (err != 0)
goto failure;
if (fib_props[cfg->fc_type].error) {
if (cfg->fc_gw_family || cfg->fc_oif || cfg->fc_mp) {
NL_SET_ERR_MSG(extack,
"Gateway, device and multipath can not be specified for this route type");
goto err_inval;
}
goto link_it;
} else {
switch (cfg->fc_type) {
case RTN_UNICAST:
case RTN_LOCAL:
case RTN_BROADCAST:
case RTN_ANYCAST:
case RTN_MULTICAST:
break;
default:
NL_SET_ERR_MSG(extack, "Invalid route type");
goto err_inval;
}
}
if (cfg->fc_scope > RT_SCOPE_HOST) {
NL_SET_ERR_MSG(extack, "Invalid scope");
goto err_inval;
}
if (fi->nh) {
err = fib_check_nexthop(fi->nh, cfg->fc_scope, extack);
if (err)
goto failure;
} else if (cfg->fc_scope == RT_SCOPE_HOST) {
struct fib_nh *nh = fi->fib_nh;
/* Local address is added. */
if (nhs != 1) {
NL_SET_ERR_MSG(extack,
"Route with host scope can not have multiple nexthops");
goto err_inval;
}
if (nh->fib_nh_gw_family) {
NL_SET_ERR_MSG(extack,
"Route with host scope can not have a gateway");
goto err_inval;
}
nh->fib_nh_scope = RT_SCOPE_NOWHERE;
nh->fib_nh_dev = dev_get_by_index(net, nh->fib_nh_oif);
err = -ENODEV;
if (!nh->fib_nh_dev)
goto failure;
netdev_tracker_alloc(nh->fib_nh_dev, &nh->fib_nh_dev_tracker,
GFP_KERNEL);
} else {
int linkdown = 0;
change_nexthops(fi) {
err = fib_check_nh(cfg->fc_nlinfo.nl_net, nexthop_nh,
cfg->fc_table, cfg->fc_scope,
extack);
if (err != 0)
goto failure;
if (nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN)
linkdown++;
} endfor_nexthops(fi)
if (linkdown == fi->fib_nhs)
fi->fib_flags |= RTNH_F_LINKDOWN;
}
if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc)) {
NL_SET_ERR_MSG(extack, "Invalid prefsrc address");
goto err_inval;
}
if (!fi->nh) {
change_nexthops(fi) {
fib_info_update_nhc_saddr(net, &nexthop_nh->nh_common,
fi->fib_scope);
if (nexthop_nh->fib_nh_gw_family == AF_INET6)
fi->fib_nh_is_v6 = true;
} endfor_nexthops(fi)
fib_rebalance(fi);
}
link_it:
ofi = fib_find_info(fi);
if (ofi) {
/* fib_table_lookup() should not see @fi yet. */
fi->fib_dead = 1;
free_fib_info(fi);
refcount_inc(&ofi->fib_treeref);
return ofi;
}
refcount_set(&fi->fib_treeref, 1);
refcount_set(&fi->fib_clntref, 1);
spin_lock_bh(&fib_info_lock);
fib_info_cnt++;
hlist_add_head(&fi->fib_hash,
&fib_info_hash[fib_info_hashfn(fi)]);
if (fi->fib_prefsrc) {
struct hlist_head *head;
head = fib_info_laddrhash_bucket(net, fi->fib_prefsrc);
hlist_add_head(&fi->fib_lhash, head);
}
if (fi->nh) {
list_add(&fi->nh_list, &nh->fi_list);
} else {
change_nexthops(fi) {
struct hlist_head *head;
if (!nexthop_nh->fib_nh_dev)
continue;
head = fib_info_devhash_bucket(nexthop_nh->fib_nh_dev);
hlist_add_head(&nexthop_nh->nh_hash, head);
} endfor_nexthops(fi)
}
spin_unlock_bh(&fib_info_lock);
return fi;
err_inval:
err = -EINVAL;
failure:
if (fi) {
/* fib_table_lookup() should not see @fi yet. */
fi->fib_dead = 1;
free_fib_info(fi);
}
return ERR_PTR(err);
}
int fib_nexthop_info(struct sk_buff *skb, const struct fib_nh_common *nhc,
u8 rt_family, unsigned char *flags, bool skip_oif)
{
if (nhc->nhc_flags & RTNH_F_DEAD)
*flags |= RTNH_F_DEAD;
if (nhc->nhc_flags & RTNH_F_LINKDOWN) {
*flags |= RTNH_F_LINKDOWN;
rcu_read_lock();
switch (nhc->nhc_family) {
case AF_INET:
if (ip_ignore_linkdown(nhc->nhc_dev))
*flags |= RTNH_F_DEAD;
break;
case AF_INET6:
if (ip6_ignore_linkdown(nhc->nhc_dev))
*flags |= RTNH_F_DEAD;
break;
}
rcu_read_unlock();
}
switch (nhc->nhc_gw_family) {
case AF_INET:
if (nla_put_in_addr(skb, RTA_GATEWAY, nhc->nhc_gw.ipv4))
goto nla_put_failure;
break;
case AF_INET6:
/* if gateway family does not match nexthop family
* gateway is encoded as RTA_VIA
*/
if (rt_family != nhc->nhc_gw_family) {
int alen = sizeof(struct in6_addr);
struct nlattr *nla;
struct rtvia *via;
nla = nla_reserve(skb, RTA_VIA, alen + 2);
if (!nla)
goto nla_put_failure;
via = nla_data(nla);
via->rtvia_family = AF_INET6;
memcpy(via->rtvia_addr, &nhc->nhc_gw.ipv6, alen);
} else if (nla_put_in6_addr(skb, RTA_GATEWAY,
&nhc->nhc_gw.ipv6) < 0) {
goto nla_put_failure;
}
break;
}
*flags |= (nhc->nhc_flags &
(RTNH_F_ONLINK | RTNH_F_OFFLOAD | RTNH_F_TRAP));
if (!skip_oif && nhc->nhc_dev &&
nla_put_u32(skb, RTA_OIF, nhc->nhc_dev->ifindex))
goto nla_put_failure;
if (nhc->nhc_lwtstate &&
lwtunnel_fill_encap(skb, nhc->nhc_lwtstate,
RTA_ENCAP, RTA_ENCAP_TYPE) < 0)
goto nla_put_failure;
return 0;
nla_put_failure:
return -EMSGSIZE;
}
EXPORT_SYMBOL_GPL(fib_nexthop_info);
#if IS_ENABLED(CONFIG_IP_ROUTE_MULTIPATH) || IS_ENABLED(CONFIG_IPV6)
int fib_add_nexthop(struct sk_buff *skb, const struct fib_nh_common *nhc,
int nh_weight, u8 rt_family, u32 nh_tclassid)
{
const struct net_device *dev = nhc->nhc_dev;
struct rtnexthop *rtnh;
unsigned char flags = 0;
rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
if (!rtnh)
goto nla_put_failure;
rtnh->rtnh_hops = nh_weight - 1;
rtnh->rtnh_ifindex = dev ? dev->ifindex : 0;
if (fib_nexthop_info(skb, nhc, rt_family, &flags, true) < 0)
goto nla_put_failure;
rtnh->rtnh_flags = flags;
if (nh_tclassid && nla_put_u32(skb, RTA_FLOW, nh_tclassid))
goto nla_put_failure;
/* length of rtnetlink header + attributes */
rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *)rtnh;
return 0;
nla_put_failure:
return -EMSGSIZE;
}
EXPORT_SYMBOL_GPL(fib_add_nexthop);
#endif
#ifdef CONFIG_IP_ROUTE_MULTIPATH
static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
{
struct nlattr *mp;
mp = nla_nest_start_noflag(skb, RTA_MULTIPATH);
if (!mp)
goto nla_put_failure;
if (unlikely(fi->nh)) {
if (nexthop_mpath_fill_node(skb, fi->nh, AF_INET) < 0)
goto nla_put_failure;
goto mp_end;
}
for_nexthops(fi) {
u32 nh_tclassid = 0;
#ifdef CONFIG_IP_ROUTE_CLASSID
nh_tclassid = nh->nh_tclassid;
#endif
if (fib_add_nexthop(skb, &nh->nh_common, nh->fib_nh_weight,
AF_INET, nh_tclassid) < 0)
goto nla_put_failure;
} endfor_nexthops(fi);
mp_end:
nla_nest_end(skb, mp);
return 0;
nla_put_failure:
return -EMSGSIZE;
}
#else
static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
{
return 0;
}
#endif
int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
const struct fib_rt_info *fri, unsigned int flags)
{
unsigned int nhs = fib_info_num_path(fri->fi);
struct fib_info *fi = fri->fi;
u32 tb_id = fri->tb_id;
struct nlmsghdr *nlh;
struct rtmsg *rtm;
nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
if (!nlh)
return -EMSGSIZE;
rtm = nlmsg_data(nlh);
rtm->rtm_family = AF_INET;
rtm->rtm_dst_len = fri->dst_len;
rtm->rtm_src_len = 0;
rtm->rtm_tos = inet_dscp_to_dsfield(fri->dscp);
if (tb_id < 256)
rtm->rtm_table = tb_id;
else
rtm->rtm_table = RT_TABLE_COMPAT;
if (nla_put_u32(skb, RTA_TABLE, tb_id))
goto nla_put_failure;
rtm->rtm_type = fri->type;
rtm->rtm_flags = fi->fib_flags;
rtm->rtm_scope = fi->fib_scope;
rtm->rtm_protocol = fi->fib_protocol;
if (rtm->rtm_dst_len &&
nla_put_in_addr(skb, RTA_DST, fri->dst))
goto nla_put_failure;
if (fi->fib_priority &&
nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
goto nla_put_failure;
if (rtnetlink_put_metrics(skb, fi->fib_metrics->metrics) < 0)
goto nla_put_failure;
if (fi->fib_prefsrc &&
nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
goto nla_put_failure;
if (fi->nh) {
if (nla_put_u32(skb, RTA_NH_ID, fi->nh->id))
goto nla_put_failure;
if (nexthop_is_blackhole(fi->nh))
rtm->rtm_type = RTN_BLACKHOLE;
if (!READ_ONCE(fi->fib_net->ipv4.sysctl_nexthop_compat_mode))
goto offload;
}
if (nhs == 1) {
const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
unsigned char flags = 0;
if (fib_nexthop_info(skb, nhc, AF_INET, &flags, false) < 0)
goto nla_put_failure;
rtm->rtm_flags = flags;
#ifdef CONFIG_IP_ROUTE_CLASSID
if (nhc->nhc_family == AF_INET) {
struct fib_nh *nh;
nh = container_of(nhc, struct fib_nh, nh_common);
if (nh->nh_tclassid &&
nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
goto nla_put_failure;
}
#endif
} else {
if (fib_add_multipath(skb, fi) < 0)
goto nla_put_failure;
}
offload:
if (fri->offload)
rtm->rtm_flags |= RTM_F_OFFLOAD;
if (fri->trap)
rtm->rtm_flags |= RTM_F_TRAP;
if (fri->offload_failed)
rtm->rtm_flags |= RTM_F_OFFLOAD_FAILED;
nlmsg_end(skb, nlh);
return 0;
nla_put_failure:
nlmsg_cancel(skb, nlh);
return -EMSGSIZE;
}
/*
* Update FIB if:
* - local address disappeared -> we must delete all the entries
* referring to it.
* - device went down -> we must shutdown all nexthops going via it.
*/
int fib_sync_down_addr(struct net_device *dev, __be32 local)
{
int tb_id = l3mdev_fib_table(dev) ? : RT_TABLE_MAIN;
struct net *net = dev_net(dev);
struct hlist_head *head;
struct fib_info *fi;
int ret = 0;
if (!fib_info_laddrhash || local == 0)
return 0;
head = fib_info_laddrhash_bucket(net, local);
hlist_for_each_entry(fi, head, fib_lhash) {
if (!net_eq(fi->fib_net, net) ||
fi->fib_tb_id != tb_id)
continue;
if (fi->fib_prefsrc == local) {
fi->fib_flags |= RTNH_F_DEAD;
fi->pfsrc_removed = true;
ret++;
}
}
return ret;
}
static int call_fib_nh_notifiers(struct fib_nh *nh,
enum fib_event_type event_type)
{
bool ignore_link_down = ip_ignore_linkdown(nh->fib_nh_dev);
struct fib_nh_notifier_info info = {
.fib_nh = nh,
};
switch (event_type) {
case FIB_EVENT_NH_ADD:
if (nh->fib_nh_flags & RTNH_F_DEAD)
break;
if (ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN)
break;
return call_fib4_notifiers(dev_net(nh->fib_nh_dev), event_type,
&info.info);
case FIB_EVENT_NH_DEL:
if ((ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN) ||
(nh->fib_nh_flags & RTNH_F_DEAD))
return call_fib4_notifiers(dev_net(nh->fib_nh_dev),
event_type, &info.info);
break;
default:
break;
}
return NOTIFY_DONE;
}
/* Update the PMTU of exceptions when:
* - the new MTU of the first hop becomes smaller than the PMTU
* - the old MTU was the same as the PMTU, and it limited discovery of
* larger MTUs on the path. With that limit raised, we can now
* discover larger MTUs
* A special case is locked exceptions, for which the PMTU is smaller
* than the minimal accepted PMTU:
* - if the new MTU is greater than the PMTU, don't make any change
* - otherwise, unlock and set PMTU
*/
void fib_nhc_update_mtu(struct fib_nh_common *nhc, u32 new, u32 orig)
{
struct fnhe_hash_bucket *bucket;
int i;
bucket = rcu_dereference_protected(nhc->nhc_exceptions, 1);
if (!bucket)
return;
for (i = 0; i < FNHE_HASH_SIZE; i++) {
struct fib_nh_exception *fnhe;
for (fnhe = rcu_dereference_protected(bucket[i].chain, 1);
fnhe;
fnhe = rcu_dereference_protected(fnhe->fnhe_next, 1)) {
if (fnhe->fnhe_mtu_locked) {
if (new <= fnhe->fnhe_pmtu) {
fnhe->fnhe_pmtu = new;
fnhe->fnhe_mtu_locked = false;
}
} else if (new < fnhe->fnhe_pmtu ||
orig == fnhe->fnhe_pmtu) {
fnhe->fnhe_pmtu = new;
}
}
}
}
void fib_sync_mtu(struct net_device *dev, u32 orig_mtu)
{
struct hlist_head *head = fib_info_devhash_bucket(dev);
struct fib_nh *nh;
hlist_for_each_entry(nh, head, nh_hash) {
if (nh->fib_nh_dev == dev)
fib_nhc_update_mtu(&nh->nh_common, dev->mtu, orig_mtu);
}
}
/* Event force Flags Description
* NETDEV_CHANGE 0 LINKDOWN Carrier OFF, not for scope host
* NETDEV_DOWN 0 LINKDOWN|DEAD Link down, not for scope host
* NETDEV_DOWN 1 LINKDOWN|DEAD Last address removed
* NETDEV_UNREGISTER 1 LINKDOWN|DEAD Device removed
*
* only used when fib_nh is built into fib_info
*/
int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
{
struct hlist_head *head = fib_info_devhash_bucket(dev);
struct fib_info *prev_fi = NULL;
int scope = RT_SCOPE_NOWHERE;
struct fib_nh *nh;
int ret = 0;
if (force)
scope = -1;
hlist_for_each_entry(nh, head, nh_hash) {
struct fib_info *fi = nh->nh_parent;
int dead;
BUG_ON(!fi->fib_nhs);
if (nh->fib_nh_dev != dev || fi == prev_fi)
continue;
prev_fi = fi;
dead = 0;
change_nexthops(fi) {
if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD)
dead++;
else if (nexthop_nh->fib_nh_dev == dev &&
nexthop_nh->fib_nh_scope != scope) {
switch (event) {
case NETDEV_DOWN:
case NETDEV_UNREGISTER:
nexthop_nh->fib_nh_flags |= RTNH_F_DEAD;
fallthrough;
case NETDEV_CHANGE:
nexthop_nh->fib_nh_flags |= RTNH_F_LINKDOWN;
break;
}
call_fib_nh_notifiers(nexthop_nh,
FIB_EVENT_NH_DEL);
dead++;
}
#ifdef CONFIG_IP_ROUTE_MULTIPATH
if (event == NETDEV_UNREGISTER &&
nexthop_nh->fib_nh_dev == dev) {
dead = fi->fib_nhs;
break;
}
#endif
} endfor_nexthops(fi)
if (dead == fi->fib_nhs) {
switch (event) {
case NETDEV_DOWN:
case NETDEV_UNREGISTER:
fi->fib_flags |= RTNH_F_DEAD;
fallthrough;
case NETDEV_CHANGE:
fi->fib_flags |= RTNH_F_LINKDOWN;
break;
}
ret++;
}
fib_rebalance(fi);
}
return ret;
}
/* Must be invoked inside of an RCU protected region. */
static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
{
struct fib_info *fi = NULL, *last_resort = NULL;
struct hlist_head *fa_head = res->fa_head;
struct fib_table *tb = res->table;
u8 slen = 32 - res->prefixlen;
int order = -1, last_idx = -1;
struct fib_alias *fa, *fa1 = NULL;
u32 last_prio = res->fi->fib_priority;
dscp_t last_dscp = 0;
hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
struct fib_info *next_fi = fa->fa_info;
struct fib_nh_common *nhc;
if (fa->fa_slen != slen)
continue;
if (fa->fa_dscp && !fib_dscp_masked_match(fa->fa_dscp, flp))
continue;
if (fa->tb_id != tb->tb_id)
continue;
if (next_fi->fib_priority > last_prio &&
fa->fa_dscp == last_dscp) {
if (last_dscp)
continue;
break;
}
if (next_fi->fib_flags & RTNH_F_DEAD)
continue;
last_dscp = fa->fa_dscp;
last_prio = next_fi->fib_priority;
if (next_fi->fib_scope != res->scope ||
fa->fa_type != RTN_UNICAST)
continue;
nhc = fib_info_nhc(next_fi, 0);
if (!nhc->nhc_gw_family || nhc->nhc_scope != RT_SCOPE_LINK)
continue;
fib_alias_accessed(fa);
if (!fi) {
if (next_fi != res->fi)
break;
fa1 = fa;
} else if (!fib_detect_death(fi, order, &last_resort,
&last_idx, fa1->fa_default)) {
fib_result_assign(res, fi);
fa1->fa_default = order;
goto out;
}
fi = next_fi;
order++;
}
if (order <= 0 || !fi) {
if (fa1)
fa1->fa_default = -1;
goto out;
}
if (!fib_detect_death(fi, order, &last_resort, &last_idx,
fa1->fa_default)) {
fib_result_assign(res, fi);
fa1->fa_default = order;
goto out;
}
if (last_idx >= 0)
fib_result_assign(res, last_resort);
fa1->fa_default = last_idx;
out:
return;
}
/*
* Dead device goes up. We wake up dead nexthops.
* It takes sense only on multipath routes.
*
* only used when fib_nh is built into fib_info
*/
int fib_sync_up(struct net_device *dev, unsigned char nh_flags)
{
struct fib_info *prev_fi;
struct hlist_head *head;
struct fib_nh *nh;
int ret;
if (!(dev->flags & IFF_UP))
return 0;
if (nh_flags & RTNH_F_DEAD) {
unsigned int flags = dev_get_flags(dev);
if (flags & (IFF_RUNNING | IFF_LOWER_UP))
nh_flags |= RTNH_F_LINKDOWN;
}
prev_fi = NULL;
head = fib_info_devhash_bucket(dev);
ret = 0;
hlist_for_each_entry(nh, head, nh_hash) {
struct fib_info *fi = nh->nh_parent;
int alive;
BUG_ON(!fi->fib_nhs);
if (nh->fib_nh_dev != dev || fi == prev_fi)
continue;
prev_fi = fi;
alive = 0;
change_nexthops(fi) {
if (!(nexthop_nh->fib_nh_flags & nh_flags)) {
alive++;
continue;
}
if (!nexthop_nh->fib_nh_dev ||
!(nexthop_nh->fib_nh_dev->flags & IFF_UP))
continue;
if (nexthop_nh->fib_nh_dev != dev ||
!__in_dev_get_rtnl(dev))
continue;
alive++;
nexthop_nh->fib_nh_flags &= ~nh_flags;
call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
} endfor_nexthops(fi)
if (alive > 0) {
fi->fib_flags &= ~nh_flags;
ret++;
}
fib_rebalance(fi);
}
return ret;
}
#ifdef CONFIG_IP_ROUTE_MULTIPATH
static bool fib_good_nh(const struct fib_nh *nh)
{
int state = NUD_REACHABLE;
if (nh->fib_nh_scope == RT_SCOPE_LINK) {
struct neighbour *n;
rcu_read_lock();
if (likely(nh->fib_nh_gw_family == AF_INET))
n = __ipv4_neigh_lookup_noref(nh->fib_nh_dev,
(__force u32)nh->fib_nh_gw4);
else if (nh->fib_nh_gw_family == AF_INET6)
n = __ipv6_neigh_lookup_noref_stub(nh->fib_nh_dev,
&nh->fib_nh_gw6);
else
n = NULL;
if (n)
state = READ_ONCE(n->nud_state);
rcu_read_unlock();
}
return !!(state & NUD_VALID);
}
void fib_select_multipath(struct fib_result *res, int hash)
{
struct fib_info *fi = res->fi;
struct net *net = fi->fib_net;
bool first = false;
if (unlikely(res->fi->nh)) {
nexthop_path_fib_result(res, hash);
return;
}
change_nexthops(fi) {
if (READ_ONCE(net->ipv4.sysctl_fib_multipath_use_neigh)) {
if (!fib_good_nh(nexthop_nh))
continue;
if (!first) {
res->nh_sel = nhsel;
res->nhc = &nexthop_nh->nh_common;
first = true;
}
}
if (hash > atomic_read(&nexthop_nh->fib_nh_upper_bound))
continue;
res->nh_sel = nhsel;
res->nhc = &nexthop_nh->nh_common;
return;
} endfor_nexthops(fi);
}
#endif
void fib_select_path(struct net *net, struct fib_result *res,
struct flowi4 *fl4, const struct sk_buff *skb)
{
if (fl4->flowi4_oif)
goto check_saddr;
#ifdef CONFIG_IP_ROUTE_MULTIPATH
if (fib_info_num_path(res->fi) > 1) {
int h = fib_multipath_hash(net, fl4, skb, NULL);
fib_select_multipath(res, h);
}
else
#endif
if (!res->prefixlen &&
res->table->tb_num_default > 1 &&
res->type == RTN_UNICAST)
fib_select_default(fl4, res);
check_saddr:
if (!fl4->saddr) {
struct net_device *l3mdev;
l3mdev = dev_get_by_index_rcu(net, fl4->flowi4_l3mdev);
if (!l3mdev ||
l3mdev_master_dev_rcu(FIB_RES_DEV(*res)) == l3mdev)
fl4->saddr = fib_result_prefsrc(net, res);
else
fl4->saddr = inet_select_addr(l3mdev, 0, RT_SCOPE_LINK);
}
}
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