linux/net/ipv4/fib_rules.c
Ido Schimmel b9455fef8b ipv4: fib_rules: Add DSCP selector support
Implement support for the new DSCP selector that allows IPv4 FIB rules
to match on the entire DSCP field, unlike the existing TOS selector that
only matches on the three lower DSCP bits.

Differentiate between both selectors by adding a new bit in the IPv4 FIB
rule structure (in an existing one byte hole) that is only set when the
'FRA_DSCP' attribute is specified by user space. Reject rules that use
both selectors.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20240911093748.3662015-3-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-09-13 21:15:44 -07:00

483 lines
11 KiB
C

// 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: policy rules.
*
* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
* Thomas Graf <tgraf@suug.ch>
*
* Fixes:
* Rani Assaf : local_rule cannot be deleted
* Marc Boucher : routing by fwmark
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/netlink.h>
#include <linux/inetdevice.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/rcupdate.h>
#include <linux/export.h>
#include <net/inet_dscp.h>
#include <net/ip.h>
#include <net/route.h>
#include <net/tcp.h>
#include <net/ip_fib.h>
#include <net/nexthop.h>
#include <net/fib_rules.h>
#include <linux/indirect_call_wrapper.h>
struct fib4_rule {
struct fib_rule common;
u8 dst_len;
u8 src_len;
dscp_t dscp;
u8 dscp_full:1; /* DSCP or TOS selector */
__be32 src;
__be32 srcmask;
__be32 dst;
__be32 dstmask;
#ifdef CONFIG_IP_ROUTE_CLASSID
u32 tclassid;
#endif
};
static bool fib4_rule_matchall(const struct fib_rule *rule)
{
struct fib4_rule *r = container_of(rule, struct fib4_rule, common);
if (r->dst_len || r->src_len || r->dscp)
return false;
return fib_rule_matchall(rule);
}
bool fib4_rule_default(const struct fib_rule *rule)
{
if (!fib4_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL ||
rule->l3mdev)
return false;
if (rule->table != RT_TABLE_LOCAL && rule->table != RT_TABLE_MAIN &&
rule->table != RT_TABLE_DEFAULT)
return false;
return true;
}
EXPORT_SYMBOL_GPL(fib4_rule_default);
int fib4_rules_dump(struct net *net, struct notifier_block *nb,
struct netlink_ext_ack *extack)
{
return fib_rules_dump(net, nb, AF_INET, extack);
}
unsigned int fib4_rules_seq_read(struct net *net)
{
return fib_rules_seq_read(net, AF_INET);
}
int __fib_lookup(struct net *net, struct flowi4 *flp,
struct fib_result *res, unsigned int flags)
{
struct fib_lookup_arg arg = {
.result = res,
.flags = flags,
};
int err;
/* update flow if oif or iif point to device enslaved to l3mdev */
l3mdev_update_flow(net, flowi4_to_flowi(flp));
err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);
#ifdef CONFIG_IP_ROUTE_CLASSID
if (arg.rule)
res->tclassid = ((struct fib4_rule *)arg.rule)->tclassid;
else
res->tclassid = 0;
#endif
if (err == -ESRCH)
err = -ENETUNREACH;
return err;
}
EXPORT_SYMBOL_GPL(__fib_lookup);
INDIRECT_CALLABLE_SCOPE int fib4_rule_action(struct fib_rule *rule,
struct flowi *flp, int flags,
struct fib_lookup_arg *arg)
{
int err = -EAGAIN;
struct fib_table *tbl;
u32 tb_id;
switch (rule->action) {
case FR_ACT_TO_TBL:
break;
case FR_ACT_UNREACHABLE:
return -ENETUNREACH;
case FR_ACT_PROHIBIT:
return -EACCES;
case FR_ACT_BLACKHOLE:
default:
return -EINVAL;
}
rcu_read_lock();
tb_id = fib_rule_get_table(rule, arg);
tbl = fib_get_table(rule->fr_net, tb_id);
if (tbl)
err = fib_table_lookup(tbl, &flp->u.ip4,
(struct fib_result *)arg->result,
arg->flags);
rcu_read_unlock();
return err;
}
INDIRECT_CALLABLE_SCOPE bool fib4_rule_suppress(struct fib_rule *rule,
int flags,
struct fib_lookup_arg *arg)
{
struct fib_result *result = arg->result;
struct net_device *dev = NULL;
if (result->fi) {
struct fib_nh_common *nhc = fib_info_nhc(result->fi, 0);
dev = nhc->nhc_dev;
}
/* do not accept result if the route does
* not meet the required prefix length
*/
if (result->prefixlen <= rule->suppress_prefixlen)
goto suppress_route;
/* do not accept result if the route uses a device
* belonging to a forbidden interface group
*/
if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
goto suppress_route;
return false;
suppress_route:
if (!(arg->flags & FIB_LOOKUP_NOREF))
fib_info_put(result->fi);
return true;
}
INDIRECT_CALLABLE_SCOPE int fib4_rule_match(struct fib_rule *rule,
struct flowi *fl, int flags)
{
struct fib4_rule *r = (struct fib4_rule *) rule;
struct flowi4 *fl4 = &fl->u.ip4;
__be32 daddr = fl4->daddr;
__be32 saddr = fl4->saddr;
if (((saddr ^ r->src) & r->srcmask) ||
((daddr ^ r->dst) & r->dstmask))
return 0;
/* When DSCP selector is used we need to match on the entire DSCP field
* in the flow information structure. When TOS selector is used we need
* to mask the upper three DSCP bits prior to matching to maintain
* legacy behavior.
*/
if (r->dscp_full && r->dscp != inet_dsfield_to_dscp(fl4->flowi4_tos))
return 0;
else if (!r->dscp_full && r->dscp &&
!fib_dscp_masked_match(r->dscp, fl4))
return 0;
if (rule->ip_proto && (rule->ip_proto != fl4->flowi4_proto))
return 0;
if (fib_rule_port_range_set(&rule->sport_range) &&
!fib_rule_port_inrange(&rule->sport_range, fl4->fl4_sport))
return 0;
if (fib_rule_port_range_set(&rule->dport_range) &&
!fib_rule_port_inrange(&rule->dport_range, fl4->fl4_dport))
return 0;
return 1;
}
static struct fib_table *fib_empty_table(struct net *net)
{
u32 id = 1;
while (1) {
if (!fib_get_table(net, id))
return fib_new_table(net, id);
if (id++ == RT_TABLE_MAX)
break;
}
return NULL;
}
static int fib4_nl2rule_dscp(const struct nlattr *nla, struct fib4_rule *rule4,
struct netlink_ext_ack *extack)
{
if (rule4->dscp) {
NL_SET_ERR_MSG(extack, "Cannot specify both TOS and DSCP");
return -EINVAL;
}
rule4->dscp = inet_dsfield_to_dscp(nla_get_u8(nla) << 2);
rule4->dscp_full = true;
return 0;
}
static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
struct fib_rule_hdr *frh,
struct nlattr **tb,
struct netlink_ext_ack *extack)
{
struct net *net = sock_net(skb->sk);
int err = -EINVAL;
struct fib4_rule *rule4 = (struct fib4_rule *) rule;
if (!inet_validate_dscp(frh->tos)) {
NL_SET_ERR_MSG(extack,
"Invalid dsfield (tos): ECN bits must be 0");
goto errout;
}
/* IPv4 currently doesn't handle high order DSCP bits correctly */
if (frh->tos & ~IPTOS_TOS_MASK) {
NL_SET_ERR_MSG(extack, "Invalid tos");
goto errout;
}
rule4->dscp = inet_dsfield_to_dscp(frh->tos);
if (tb[FRA_DSCP] &&
fib4_nl2rule_dscp(tb[FRA_DSCP], rule4, extack) < 0)
goto errout;
/* split local/main if they are not already split */
err = fib_unmerge(net);
if (err)
goto errout;
if (rule->table == RT_TABLE_UNSPEC && !rule->l3mdev) {
if (rule->action == FR_ACT_TO_TBL) {
struct fib_table *table;
table = fib_empty_table(net);
if (!table) {
err = -ENOBUFS;
goto errout;
}
rule->table = table->tb_id;
}
}
if (frh->src_len)
rule4->src = nla_get_in_addr(tb[FRA_SRC]);
if (frh->dst_len)
rule4->dst = nla_get_in_addr(tb[FRA_DST]);
#ifdef CONFIG_IP_ROUTE_CLASSID
if (tb[FRA_FLOW]) {
rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
if (rule4->tclassid)
atomic_inc(&net->ipv4.fib_num_tclassid_users);
}
#endif
if (fib_rule_requires_fldissect(rule))
net->ipv4.fib_rules_require_fldissect++;
rule4->src_len = frh->src_len;
rule4->srcmask = inet_make_mask(rule4->src_len);
rule4->dst_len = frh->dst_len;
rule4->dstmask = inet_make_mask(rule4->dst_len);
net->ipv4.fib_has_custom_rules = true;
err = 0;
errout:
return err;
}
static int fib4_rule_delete(struct fib_rule *rule)
{
struct net *net = rule->fr_net;
int err;
/* split local/main if they are not already split */
err = fib_unmerge(net);
if (err)
goto errout;
#ifdef CONFIG_IP_ROUTE_CLASSID
if (((struct fib4_rule *)rule)->tclassid)
atomic_dec(&net->ipv4.fib_num_tclassid_users);
#endif
net->ipv4.fib_has_custom_rules = true;
if (net->ipv4.fib_rules_require_fldissect &&
fib_rule_requires_fldissect(rule))
net->ipv4.fib_rules_require_fldissect--;
errout:
return err;
}
static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
struct nlattr **tb)
{
struct fib4_rule *rule4 = (struct fib4_rule *) rule;
if (frh->src_len && (rule4->src_len != frh->src_len))
return 0;
if (frh->dst_len && (rule4->dst_len != frh->dst_len))
return 0;
if (frh->tos &&
(rule4->dscp_full ||
inet_dscp_to_dsfield(rule4->dscp) != frh->tos))
return 0;
if (tb[FRA_DSCP]) {
dscp_t dscp;
dscp = inet_dsfield_to_dscp(nla_get_u8(tb[FRA_DSCP]) << 2);
if (!rule4->dscp_full || rule4->dscp != dscp)
return 0;
}
#ifdef CONFIG_IP_ROUTE_CLASSID
if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
return 0;
#endif
if (frh->src_len && (rule4->src != nla_get_in_addr(tb[FRA_SRC])))
return 0;
if (frh->dst_len && (rule4->dst != nla_get_in_addr(tb[FRA_DST])))
return 0;
return 1;
}
static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
struct fib_rule_hdr *frh)
{
struct fib4_rule *rule4 = (struct fib4_rule *) rule;
frh->dst_len = rule4->dst_len;
frh->src_len = rule4->src_len;
if (rule4->dscp_full) {
frh->tos = 0;
if (nla_put_u8(skb, FRA_DSCP,
inet_dscp_to_dsfield(rule4->dscp) >> 2))
goto nla_put_failure;
} else {
frh->tos = inet_dscp_to_dsfield(rule4->dscp);
}
if ((rule4->dst_len &&
nla_put_in_addr(skb, FRA_DST, rule4->dst)) ||
(rule4->src_len &&
nla_put_in_addr(skb, FRA_SRC, rule4->src)))
goto nla_put_failure;
#ifdef CONFIG_IP_ROUTE_CLASSID
if (rule4->tclassid &&
nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
goto nla_put_failure;
#endif
return 0;
nla_put_failure:
return -ENOBUFS;
}
static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
{
return nla_total_size(4) /* dst */
+ nla_total_size(4) /* src */
+ nla_total_size(4) /* flow */
+ nla_total_size(1); /* dscp */
}
static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
{
rt_cache_flush(ops->fro_net);
}
static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {
.family = AF_INET,
.rule_size = sizeof(struct fib4_rule),
.addr_size = sizeof(u32),
.action = fib4_rule_action,
.suppress = fib4_rule_suppress,
.match = fib4_rule_match,
.configure = fib4_rule_configure,
.delete = fib4_rule_delete,
.compare = fib4_rule_compare,
.fill = fib4_rule_fill,
.nlmsg_payload = fib4_rule_nlmsg_payload,
.flush_cache = fib4_rule_flush_cache,
.nlgroup = RTNLGRP_IPV4_RULE,
.owner = THIS_MODULE,
};
static int fib_default_rules_init(struct fib_rules_ops *ops)
{
int err;
err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL);
if (err < 0)
return err;
err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN);
if (err < 0)
return err;
err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT);
if (err < 0)
return err;
return 0;
}
int __net_init fib4_rules_init(struct net *net)
{
int err;
struct fib_rules_ops *ops;
ops = fib_rules_register(&fib4_rules_ops_template, net);
if (IS_ERR(ops))
return PTR_ERR(ops);
err = fib_default_rules_init(ops);
if (err < 0)
goto fail;
net->ipv4.rules_ops = ops;
net->ipv4.fib_has_custom_rules = false;
net->ipv4.fib_rules_require_fldissect = 0;
return 0;
fail:
/* also cleans all rules already added */
fib_rules_unregister(ops);
return err;
}
void __net_exit fib4_rules_exit(struct net *net)
{
fib_rules_unregister(net->ipv4.rules_ops);
}