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linux/include/net/ip_fib.h
Ido Schimmel 338bb57e4c ipv4: Fix incorrect TOS in route get reply 
The TOS value that is returned to user space in the route get reply is
the one with which the lookup was performed ('fl4->flowi4_tos'). This is
fine when the matched route is configured with a TOS as it would not
match if its TOS value did not match the one with which the lookup was
performed.

However, matching on TOS is only performed when the route's TOS is not
zero. It is therefore possible to have the kernel incorrectly return a
non-zero TOS:

 # ip link add name dummy1 up type dummy
 # ip address add 192.0.2.1/24 dev dummy1
 # ip route get 192.0.2.2 tos 0xfc
 192.0.2.2 tos 0x1c dev dummy1 src 192.0.2.1 uid 0
     cache

Fix by adding a DSCP field to the FIB result structure (inside an
existing 4 bytes hole), populating it in the route lookup and using it
when filling the route get reply.

Output after the patch:

 # ip link add name dummy1 up type dummy
 # ip address add 192.0.2.1/24 dev dummy1
 # ip route get 192.0.2.2 tos 0xfc
 192.0.2.2 dev dummy1 src 192.0.2.1 uid 0
     cache

Fixes: 1a00fee4ff ("ipv4: Remove rt_key_{src,dst,tos} from struct rtable.")
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2024-07-18 11:11:02 +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.
*
* Definitions for the Forwarding Information Base.
*
* Authors: A.N.Kuznetsov, <kuznet@ms2.inr.ac.ru>
*/
#ifndef _NET_IP_FIB_H
#define _NET_IP_FIB_H
#include <net/flow.h>
#include <linux/seq_file.h>
#include <linux/rcupdate.h>
#include <net/fib_notifier.h>
#include <net/fib_rules.h>
#include <net/inet_dscp.h>
#include <net/inetpeer.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/refcount.h>
struct fib_config {
u8 fc_dst_len;
dscp_t fc_dscp;
u8 fc_protocol;
u8 fc_scope;
u8 fc_type;
u8 fc_gw_family;
/* 2 bytes unused */
u32 fc_table;
__be32 fc_dst;
union {
__be32 fc_gw4;
struct in6_addr fc_gw6;
};
int fc_oif;
u32 fc_flags;
u32 fc_priority;
__be32 fc_prefsrc;
u32 fc_nh_id;
struct nlattr *fc_mx;
struct rtnexthop *fc_mp;
int fc_mx_len;
int fc_mp_len;
u32 fc_flow;
u32 fc_nlflags;
struct nl_info fc_nlinfo;
struct nlattr *fc_encap;
u16 fc_encap_type;
};
struct fib_info;
struct rtable;
struct fib_nh_exception {
struct fib_nh_exception __rcu *fnhe_next;
int fnhe_genid;
__be32 fnhe_daddr;
u32 fnhe_pmtu;
bool fnhe_mtu_locked;
__be32 fnhe_gw;
unsigned long fnhe_expires;
struct rtable __rcu *fnhe_rth_input;
struct rtable __rcu *fnhe_rth_output;
unsigned long fnhe_stamp;
struct rcu_head rcu;
};
struct fnhe_hash_bucket {
struct fib_nh_exception __rcu *chain;
};
#define FNHE_HASH_SHIFT 11
#define FNHE_HASH_SIZE (1 << FNHE_HASH_SHIFT)
#define FNHE_RECLAIM_DEPTH 5
struct fib_nh_common {
struct net_device *nhc_dev;
netdevice_tracker nhc_dev_tracker;
int nhc_oif;
unsigned char nhc_scope;
u8 nhc_family;
u8 nhc_gw_family;
unsigned char nhc_flags;
struct lwtunnel_state *nhc_lwtstate;
union {
__be32 ipv4;
struct in6_addr ipv6;
} nhc_gw;
int nhc_weight;
atomic_t nhc_upper_bound;
/* v4 specific, but allows fib6_nh with v4 routes */
struct rtable __rcu * __percpu *nhc_pcpu_rth_output;
struct rtable __rcu *nhc_rth_input;
struct fnhe_hash_bucket __rcu *nhc_exceptions;
};
struct fib_nh {
struct fib_nh_common nh_common;
struct hlist_node nh_hash;
struct fib_info *nh_parent;
#ifdef CONFIG_IP_ROUTE_CLASSID
__u32 nh_tclassid;
#endif
__be32 nh_saddr;
int nh_saddr_genid;
#define fib_nh_family nh_common.nhc_family
#define fib_nh_dev nh_common.nhc_dev
#define fib_nh_dev_tracker nh_common.nhc_dev_tracker
#define fib_nh_oif nh_common.nhc_oif
#define fib_nh_flags nh_common.nhc_flags
#define fib_nh_lws nh_common.nhc_lwtstate
#define fib_nh_scope nh_common.nhc_scope
#define fib_nh_gw_family nh_common.nhc_gw_family
#define fib_nh_gw4 nh_common.nhc_gw.ipv4
#define fib_nh_gw6 nh_common.nhc_gw.ipv6
#define fib_nh_weight nh_common.nhc_weight
#define fib_nh_upper_bound nh_common.nhc_upper_bound
};
/*
* This structure contains data shared by many of routes.
*/
struct nexthop;
struct fib_info {
struct hlist_node fib_hash;
struct hlist_node fib_lhash;
struct list_head nh_list;
struct net *fib_net;
refcount_t fib_treeref;
refcount_t fib_clntref;
unsigned int fib_flags;
unsigned char fib_dead;
unsigned char fib_protocol;
unsigned char fib_scope;
unsigned char fib_type;
__be32 fib_prefsrc;
u32 fib_tb_id;
u32 fib_priority;
struct dst_metrics *fib_metrics;
#define fib_mtu fib_metrics->metrics[RTAX_MTU-1]
#define fib_window fib_metrics->metrics[RTAX_WINDOW-1]
#define fib_rtt fib_metrics->metrics[RTAX_RTT-1]
#define fib_advmss fib_metrics->metrics[RTAX_ADVMSS-1]
int fib_nhs;
bool fib_nh_is_v6;
bool nh_updated;
bool pfsrc_removed;
struct nexthop *nh;
struct rcu_head rcu;
struct fib_nh fib_nh[] __counted_by(fib_nhs);
};
#ifdef CONFIG_IP_MULTIPLE_TABLES
struct fib_rule;
#endif
struct fib_table;
struct fib_result {
__be32 prefix;
unsigned char prefixlen;
unsigned char nh_sel;
unsigned char type;
unsigned char scope;
u32 tclassid;
dscp_t dscp;
struct fib_nh_common *nhc;
struct fib_info *fi;
struct fib_table *table;
struct hlist_head *fa_head;
};
struct fib_result_nl {
__be32 fl_addr; /* To be looked up*/
u32 fl_mark;
unsigned char fl_tos;
unsigned char fl_scope;
unsigned char tb_id_in;
unsigned char tb_id; /* Results */
unsigned char prefixlen;
unsigned char nh_sel;
unsigned char type;
unsigned char scope;
int err;
};
#ifdef CONFIG_IP_MULTIPLE_TABLES
#define FIB_TABLE_HASHSZ 256
#else
#define FIB_TABLE_HASHSZ 2
#endif
__be32 fib_info_update_nhc_saddr(struct net *net, struct fib_nh_common *nhc,
unsigned char scope);
__be32 fib_result_prefsrc(struct net *net, struct fib_result *res);
#define FIB_RES_NHC(res) ((res).nhc)
#define FIB_RES_DEV(res) (FIB_RES_NHC(res)->nhc_dev)
#define FIB_RES_OIF(res) (FIB_RES_NHC(res)->nhc_oif)
struct fib_rt_info {
struct fib_info *fi;
u32 tb_id;
__be32 dst;
int dst_len;
dscp_t dscp;
u8 type;
u8 offload:1,
trap:1,
offload_failed:1,
unused:5;
};
struct fib_entry_notifier_info {
struct fib_notifier_info info; /* must be first */
u32 dst;
int dst_len;
struct fib_info *fi;
dscp_t dscp;
u8 type;
u32 tb_id;
};
struct fib_nh_notifier_info {
struct fib_notifier_info info; /* must be first */
struct fib_nh *fib_nh;
};
int call_fib4_notifier(struct notifier_block *nb,
enum fib_event_type event_type,
struct fib_notifier_info *info);
int call_fib4_notifiers(struct net *net, enum fib_event_type event_type,
struct fib_notifier_info *info);
int __net_init fib4_notifier_init(struct net *net);
void __net_exit fib4_notifier_exit(struct net *net);
void fib_info_notify_update(struct net *net, struct nl_info *info);
int fib_notify(struct net *net, struct notifier_block *nb,
struct netlink_ext_ack *extack);
struct fib_table {
struct hlist_node tb_hlist;
u32 tb_id;
int tb_num_default;
struct rcu_head rcu;
unsigned long *tb_data;
unsigned long __data[];
};
struct fib_dump_filter {
u32 table_id;
/* filter_set is an optimization that an entry is set */
bool filter_set;
bool dump_routes;
bool dump_exceptions;
bool rtnl_held;
unsigned char protocol;
unsigned char rt_type;
unsigned int flags;
struct net_device *dev;
};
int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
struct fib_result *res, int fib_flags);
int fib_table_insert(struct net *, struct fib_table *, struct fib_config *,
struct netlink_ext_ack *extack);
int fib_table_delete(struct net *, struct fib_table *, struct fib_config *,
struct netlink_ext_ack *extack);
int fib_table_dump(struct fib_table *table, struct sk_buff *skb,
struct netlink_callback *cb, struct fib_dump_filter *filter);
int fib_table_flush(struct net *net, struct fib_table *table, bool flush_all);
struct fib_table *fib_trie_unmerge(struct fib_table *main_tb);
void fib_table_flush_external(struct fib_table *table);
void fib_free_table(struct fib_table *tb);
#ifndef CONFIG_IP_MULTIPLE_TABLES
#define TABLE_LOCAL_INDEX (RT_TABLE_LOCAL & (FIB_TABLE_HASHSZ - 1))
#define TABLE_MAIN_INDEX (RT_TABLE_MAIN & (FIB_TABLE_HASHSZ - 1))
static inline struct fib_table *fib_get_table(struct net *net, u32 id)
{
struct hlist_node *tb_hlist;
struct hlist_head *ptr;
ptr = id == RT_TABLE_LOCAL ?
&net->ipv4.fib_table_hash[TABLE_LOCAL_INDEX] :
&net->ipv4.fib_table_hash[TABLE_MAIN_INDEX];
tb_hlist = rcu_dereference_rtnl(hlist_first_rcu(ptr));
return hlist_entry(tb_hlist, struct fib_table, tb_hlist);
}
static inline struct fib_table *fib_new_table(struct net *net, u32 id)
{
return fib_get_table(net, id);
}
static inline int fib_lookup(struct net *net, const struct flowi4 *flp,
struct fib_result *res, unsigned int flags)
{
struct fib_table *tb;
int err = -ENETUNREACH;
rcu_read_lock();
tb = fib_get_table(net, RT_TABLE_MAIN);
if (tb)
err = fib_table_lookup(tb, flp, res, flags | FIB_LOOKUP_NOREF);
if (err == -EAGAIN)
err = -ENETUNREACH;
rcu_read_unlock();
return err;
}
static inline bool fib4_has_custom_rules(const struct net *net)
{
return false;
}
static inline bool fib4_rule_default(const struct fib_rule *rule)
{
return true;
}
static inline int fib4_rules_dump(struct net *net, struct notifier_block *nb,
struct netlink_ext_ack *extack)
{
return 0;
}
static inline unsigned int fib4_rules_seq_read(struct net *net)
{
return 0;
}
static inline bool fib4_rules_early_flow_dissect(struct net *net,
struct sk_buff *skb,
struct flowi4 *fl4,
struct flow_keys *flkeys)
{
return false;
}
#else /* CONFIG_IP_MULTIPLE_TABLES */
int __net_init fib4_rules_init(struct net *net);
void __net_exit fib4_rules_exit(struct net *net);
struct fib_table *fib_new_table(struct net *net, u32 id);
struct fib_table *fib_get_table(struct net *net, u32 id);
int __fib_lookup(struct net *net, struct flowi4 *flp,
struct fib_result *res, unsigned int flags);
static inline int fib_lookup(struct net *net, struct flowi4 *flp,
struct fib_result *res, unsigned int flags)
{
struct fib_table *tb;
int err = -ENETUNREACH;
flags |= FIB_LOOKUP_NOREF;
if (net->ipv4.fib_has_custom_rules)
return __fib_lookup(net, flp, res, flags);
rcu_read_lock();
res->tclassid = 0;
tb = rcu_dereference_rtnl(net->ipv4.fib_main);
if (tb)
err = fib_table_lookup(tb, flp, res, flags);
if (!err)
goto out;
tb = rcu_dereference_rtnl(net->ipv4.fib_default);
if (tb)
err = fib_table_lookup(tb, flp, res, flags);
out:
if (err == -EAGAIN)
err = -ENETUNREACH;
rcu_read_unlock();
return err;
}
static inline bool fib4_has_custom_rules(const struct net *net)
{
return net->ipv4.fib_has_custom_rules;
}
bool fib4_rule_default(const struct fib_rule *rule);
int fib4_rules_dump(struct net *net, struct notifier_block *nb,
struct netlink_ext_ack *extack);
unsigned int fib4_rules_seq_read(struct net *net);
static inline bool fib4_rules_early_flow_dissect(struct net *net,
struct sk_buff *skb,
struct flowi4 *fl4,
struct flow_keys *flkeys)
{
unsigned int flag = FLOW_DISSECTOR_F_STOP_AT_ENCAP;
if (!net->ipv4.fib_rules_require_fldissect)
return false;
memset(flkeys, 0, sizeof(*flkeys));
__skb_flow_dissect(net, skb, &flow_keys_dissector,
flkeys, NULL, 0, 0, 0, flag);
fl4->fl4_sport = flkeys->ports.src;
fl4->fl4_dport = flkeys->ports.dst;
fl4->flowi4_proto = flkeys->basic.ip_proto;
return true;
}
#endif /* CONFIG_IP_MULTIPLE_TABLES */
/* Exported by fib_frontend.c */
extern const struct nla_policy rtm_ipv4_policy[];
void ip_fib_init(void);
int fib_gw_from_via(struct fib_config *cfg, struct nlattr *nla,
struct netlink_ext_ack *extack);
__be32 fib_compute_spec_dst(struct sk_buff *skb);
bool fib_info_nh_uses_dev(struct fib_info *fi, const struct net_device *dev);
int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
u8 tos, int oif, struct net_device *dev,
struct in_device *idev, u32 *itag);
#ifdef CONFIG_IP_ROUTE_CLASSID
static inline int fib_num_tclassid_users(struct net *net)
{
return atomic_read(&net->ipv4.fib_num_tclassid_users);
}
#else
static inline int fib_num_tclassid_users(struct net *net)
{
return 0;
}
#endif
int fib_unmerge(struct net *net);
static inline bool nhc_l3mdev_matches_dev(const struct fib_nh_common *nhc,
const struct net_device *dev)
{
if (nhc->nhc_dev == dev ||
l3mdev_master_ifindex_rcu(nhc->nhc_dev) == dev->ifindex)
return true;
return false;
}
/* Exported by fib_semantics.c */
int ip_fib_check_default(__be32 gw, struct net_device *dev);
int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force);
int fib_sync_down_addr(struct net_device *dev, __be32 local);
int fib_sync_up(struct net_device *dev, unsigned char nh_flags);
void fib_sync_mtu(struct net_device *dev, u32 orig_mtu);
void fib_nhc_update_mtu(struct fib_nh_common *nhc, u32 new, u32 orig);
/* Fields used for sysctl_fib_multipath_hash_fields.
* Common to IPv4 and IPv6.
*
* Add new fields at the end. This is user API.
*/
#define FIB_MULTIPATH_HASH_FIELD_SRC_IP BIT(0)
#define FIB_MULTIPATH_HASH_FIELD_DST_IP BIT(1)
#define FIB_MULTIPATH_HASH_FIELD_IP_PROTO BIT(2)
#define FIB_MULTIPATH_HASH_FIELD_FLOWLABEL BIT(3)
#define FIB_MULTIPATH_HASH_FIELD_SRC_PORT BIT(4)
#define FIB_MULTIPATH_HASH_FIELD_DST_PORT BIT(5)
#define FIB_MULTIPATH_HASH_FIELD_INNER_SRC_IP BIT(6)
#define FIB_MULTIPATH_HASH_FIELD_INNER_DST_IP BIT(7)
#define FIB_MULTIPATH_HASH_FIELD_INNER_IP_PROTO BIT(8)
#define FIB_MULTIPATH_HASH_FIELD_INNER_FLOWLABEL BIT(9)
#define FIB_MULTIPATH_HASH_FIELD_INNER_SRC_PORT BIT(10)
#define FIB_MULTIPATH_HASH_FIELD_INNER_DST_PORT BIT(11)
#define FIB_MULTIPATH_HASH_FIELD_OUTER_MASK \
(FIB_MULTIPATH_HASH_FIELD_SRC_IP | \
FIB_MULTIPATH_HASH_FIELD_DST_IP | \
FIB_MULTIPATH_HASH_FIELD_IP_PROTO | \
FIB_MULTIPATH_HASH_FIELD_FLOWLABEL | \
FIB_MULTIPATH_HASH_FIELD_SRC_PORT | \
FIB_MULTIPATH_HASH_FIELD_DST_PORT)
#define FIB_MULTIPATH_HASH_FIELD_INNER_MASK \
(FIB_MULTIPATH_HASH_FIELD_INNER_SRC_IP | \
FIB_MULTIPATH_HASH_FIELD_INNER_DST_IP | \
FIB_MULTIPATH_HASH_FIELD_INNER_IP_PROTO | \
FIB_MULTIPATH_HASH_FIELD_INNER_FLOWLABEL | \
FIB_MULTIPATH_HASH_FIELD_INNER_SRC_PORT | \
FIB_MULTIPATH_HASH_FIELD_INNER_DST_PORT)
#define FIB_MULTIPATH_HASH_FIELD_ALL_MASK \
(FIB_MULTIPATH_HASH_FIELD_OUTER_MASK | \
FIB_MULTIPATH_HASH_FIELD_INNER_MASK)
#define FIB_MULTIPATH_HASH_FIELD_DEFAULT_MASK \
(FIB_MULTIPATH_HASH_FIELD_SRC_IP | \
FIB_MULTIPATH_HASH_FIELD_DST_IP | \
FIB_MULTIPATH_HASH_FIELD_IP_PROTO)
#ifdef CONFIG_IP_ROUTE_MULTIPATH
int fib_multipath_hash(const struct net *net, const struct flowi4 *fl4,
const struct sk_buff *skb, struct flow_keys *flkeys);
static void
fib_multipath_hash_construct_key(siphash_key_t *key, u32 mp_seed)
{
u64 mp_seed_64 = mp_seed;
key->key[0] = (mp_seed_64 << 32) | mp_seed_64;
key->key[1] = key->key[0];
}
static inline u32 fib_multipath_hash_from_keys(const struct net *net,
struct flow_keys *keys)
{
siphash_aligned_key_t hash_key;
u32 mp_seed;
mp_seed = READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_seed).mp_seed;
fib_multipath_hash_construct_key(&hash_key, mp_seed);
return flow_hash_from_keys_seed(keys, &hash_key);
}
#else
static inline u32 fib_multipath_hash_from_keys(const struct net *net,
struct flow_keys *keys)
{
return flow_hash_from_keys(keys);
}
#endif
int fib_check_nh(struct net *net, struct fib_nh *nh, u32 table, u8 scope,
struct netlink_ext_ack *extack);
void fib_select_multipath(struct fib_result *res, int hash);
void fib_select_path(struct net *net, struct fib_result *res,
struct flowi4 *fl4, const struct sk_buff *skb);
int fib_nh_init(struct net *net, struct fib_nh *fib_nh,
struct fib_config *cfg, int nh_weight,
struct netlink_ext_ack *extack);
void fib_nh_release(struct net *net, struct fib_nh *fib_nh);
int fib_nh_common_init(struct net *net, struct fib_nh_common *nhc,
struct nlattr *fc_encap, u16 fc_encap_type,
void *cfg, gfp_t gfp_flags,
struct netlink_ext_ack *extack);
void fib_nh_common_release(struct fib_nh_common *nhc);
/* Exported by fib_trie.c */
void fib_alias_hw_flags_set(struct net *net, const struct fib_rt_info *fri);
void fib_trie_init(void);
struct fib_table *fib_trie_table(u32 id, struct fib_table *alias);
bool fib_lookup_good_nhc(const struct fib_nh_common *nhc, int fib_flags,
const struct flowi4 *flp);
static inline void fib_combine_itag(u32 *itag, const struct fib_result *res)
{
#ifdef CONFIG_IP_ROUTE_CLASSID
struct fib_nh_common *nhc = res->nhc;
#ifdef CONFIG_IP_MULTIPLE_TABLES
u32 rtag;
#endif
if (nhc->nhc_family == AF_INET) {
struct fib_nh *nh;
nh = container_of(nhc, struct fib_nh, nh_common);
*itag = nh->nh_tclassid << 16;
} else {
*itag = 0;
}
#ifdef CONFIG_IP_MULTIPLE_TABLES
rtag = res->tclassid;
if (*itag == 0)
*itag = (rtag<<16);
*itag |= (rtag>>16);
#endif
#endif
}
void fib_flush(struct net *net);
void free_fib_info(struct fib_info *fi);
static inline void fib_info_hold(struct fib_info *fi)
{
refcount_inc(&fi->fib_clntref);
}
static inline void fib_info_put(struct fib_info *fi)
{
if (refcount_dec_and_test(&fi->fib_clntref))
free_fib_info(fi);
}
#ifdef CONFIG_PROC_FS
int __net_init fib_proc_init(struct net *net);
void __net_exit fib_proc_exit(struct net *net);
#else
static inline int fib_proc_init(struct net *net)
{
return 0;
}
static inline void fib_proc_exit(struct net *net)
{
}
#endif
u32 ip_mtu_from_fib_result(struct fib_result *res, __be32 daddr);
int ip_valid_fib_dump_req(struct net *net, const struct nlmsghdr *nlh,
struct fib_dump_filter *filter,
struct netlink_callback *cb);
int fib_nexthop_info(struct sk_buff *skb, const struct fib_nh_common *nh,
u8 rt_family, unsigned char *flags, bool skip_oif);
int fib_add_nexthop(struct sk_buff *skb, const struct fib_nh_common *nh,
int nh_weight, u8 rt_family, u32 nh_tclassid);
#endif /* _NET_FIB_H */
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