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linux/net/core/lwtunnel.c
David Ahern 8bda81a4d4 lwtunnel: Validate RTA_ENCAP_TYPE attribute length 
lwtunnel_valid_encap_type_attr is used to validate encap attributes
within a multipath route. Add length validation checking to the type.

lwtunnel_valid_encap_type_attr is called converting attributes to
fib{6,}_config struct which means it is used before fib_get_nhs,
ip6_route_multipath_add, and ip6_route_multipath_del - other
locations that use rtnh_ok and then nla_get_u16 on RTA_ENCAP_TYPE
attribute.

Fixes: 9ed59592e3 ("lwtunnel: fix autoload of lwt modules")

Signed-off-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-12-31 14:31:59 +00:00

424 lines
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* lwtunnel Infrastructure for light weight tunnels like mpls
*
* Authors: Roopa Prabhu, <roopa@cumulusnetworks.com>
*/
#include <linux/capability.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/lwtunnel.h>
#include <linux/in.h>
#include <linux/init.h>
#include <linux/err.h>
#include <net/lwtunnel.h>
#include <net/rtnetlink.h>
#include <net/ip6_fib.h>
#include <net/rtnh.h>
DEFINE_STATIC_KEY_FALSE(nf_hooks_lwtunnel_enabled);
EXPORT_SYMBOL_GPL(nf_hooks_lwtunnel_enabled);
#ifdef CONFIG_MODULES
static const char *lwtunnel_encap_str(enum lwtunnel_encap_types encap_type)
{
/* Only lwt encaps implemented without using an interface for
* the encap need to return a string here.
*/
switch (encap_type) {
case LWTUNNEL_ENCAP_MPLS:
return "MPLS";
case LWTUNNEL_ENCAP_ILA:
return "ILA";
case LWTUNNEL_ENCAP_SEG6:
return "SEG6";
case LWTUNNEL_ENCAP_BPF:
return "BPF";
case LWTUNNEL_ENCAP_SEG6_LOCAL:
return "SEG6LOCAL";
case LWTUNNEL_ENCAP_RPL:
return "RPL";
case LWTUNNEL_ENCAP_IOAM6:
return "IOAM6";
case LWTUNNEL_ENCAP_IP6:
case LWTUNNEL_ENCAP_IP:
case LWTUNNEL_ENCAP_NONE:
case __LWTUNNEL_ENCAP_MAX:
/* should not have got here */
WARN_ON(1);
break;
}
return NULL;
}
#endif /* CONFIG_MODULES */
struct lwtunnel_state *lwtunnel_state_alloc(int encap_len)
{
struct lwtunnel_state *lws;
lws = kzalloc(sizeof(*lws) + encap_len, GFP_ATOMIC);
return lws;
}
EXPORT_SYMBOL_GPL(lwtunnel_state_alloc);
static const struct lwtunnel_encap_ops __rcu *
lwtun_encaps[LWTUNNEL_ENCAP_MAX + 1] __read_mostly;
int lwtunnel_encap_add_ops(const struct lwtunnel_encap_ops *ops,
unsigned int num)
{
if (num > LWTUNNEL_ENCAP_MAX)
return -ERANGE;
return !cmpxchg((const struct lwtunnel_encap_ops **)
&lwtun_encaps[num],
NULL, ops) ? 0 : -1;
}
EXPORT_SYMBOL_GPL(lwtunnel_encap_add_ops);
int lwtunnel_encap_del_ops(const struct lwtunnel_encap_ops *ops,
unsigned int encap_type)
{
int ret;
if (encap_type == LWTUNNEL_ENCAP_NONE ||
encap_type > LWTUNNEL_ENCAP_MAX)
return -ERANGE;
ret = (cmpxchg((const struct lwtunnel_encap_ops **)
&lwtun_encaps[encap_type],
ops, NULL) == ops) ? 0 : -1;
synchronize_net();
return ret;
}
EXPORT_SYMBOL_GPL(lwtunnel_encap_del_ops);
int lwtunnel_build_state(struct net *net, u16 encap_type,
struct nlattr *encap, unsigned int family,
const void *cfg, struct lwtunnel_state **lws,
struct netlink_ext_ack *extack)
{
const struct lwtunnel_encap_ops *ops;
bool found = false;
int ret = -EINVAL;
if (encap_type == LWTUNNEL_ENCAP_NONE ||
encap_type > LWTUNNEL_ENCAP_MAX) {
NL_SET_ERR_MSG_ATTR(extack, encap,
"Unknown LWT encapsulation type");
return ret;
}
ret = -EOPNOTSUPP;
rcu_read_lock();
ops = rcu_dereference(lwtun_encaps[encap_type]);
if (likely(ops && ops->build_state && try_module_get(ops->owner)))
found = true;
rcu_read_unlock();
if (found) {
ret = ops->build_state(net, encap, family, cfg, lws, extack);
if (ret)
module_put(ops->owner);
} else {
/* don't rely on -EOPNOTSUPP to detect match as build_state
* handlers could return it
*/
NL_SET_ERR_MSG_ATTR(extack, encap,
"LWT encapsulation type not supported");
}
return ret;
}
EXPORT_SYMBOL_GPL(lwtunnel_build_state);
int lwtunnel_valid_encap_type(u16 encap_type, struct netlink_ext_ack *extack)
{
const struct lwtunnel_encap_ops *ops;
int ret = -EINVAL;
if (encap_type == LWTUNNEL_ENCAP_NONE ||
encap_type > LWTUNNEL_ENCAP_MAX) {
NL_SET_ERR_MSG(extack, "Unknown lwt encapsulation type");
return ret;
}
rcu_read_lock();
ops = rcu_dereference(lwtun_encaps[encap_type]);
rcu_read_unlock();
#ifdef CONFIG_MODULES
if (!ops) {
const char *encap_type_str = lwtunnel_encap_str(encap_type);
if (encap_type_str) {
__rtnl_unlock();
request_module("rtnl-lwt-%s", encap_type_str);
rtnl_lock();
rcu_read_lock();
ops = rcu_dereference(lwtun_encaps[encap_type]);
rcu_read_unlock();
}
}
#endif
ret = ops ? 0 : -EOPNOTSUPP;
if (ret < 0)
NL_SET_ERR_MSG(extack, "lwt encapsulation type not supported");
return ret;
}
EXPORT_SYMBOL_GPL(lwtunnel_valid_encap_type);
int lwtunnel_valid_encap_type_attr(struct nlattr *attr, int remaining,
struct netlink_ext_ack *extack)
{
struct rtnexthop *rtnh = (struct rtnexthop *)attr;
struct nlattr *nla_entype;
struct nlattr *attrs;
u16 encap_type;
int attrlen;
while (rtnh_ok(rtnh, remaining)) {
attrlen = rtnh_attrlen(rtnh);
if (attrlen > 0) {
attrs = rtnh_attrs(rtnh);
nla_entype = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
if (nla_entype) {
if (nla_len(nla_entype) < sizeof(u16)) {
NL_SET_ERR_MSG(extack, "Invalid RTA_ENCAP_TYPE");
return -EINVAL;
}
encap_type = nla_get_u16(nla_entype);
if (lwtunnel_valid_encap_type(encap_type,
extack) != 0)
return -EOPNOTSUPP;
}
}
rtnh = rtnh_next(rtnh, &remaining);
}
return 0;
}
EXPORT_SYMBOL_GPL(lwtunnel_valid_encap_type_attr);
void lwtstate_free(struct lwtunnel_state *lws)
{
const struct lwtunnel_encap_ops *ops = lwtun_encaps[lws->type];
if (ops->destroy_state) {
ops->destroy_state(lws);
kfree_rcu(lws, rcu);
} else {
kfree(lws);
}
module_put(ops->owner);
}
EXPORT_SYMBOL_GPL(lwtstate_free);
int lwtunnel_fill_encap(struct sk_buff *skb, struct lwtunnel_state *lwtstate,
int encap_attr, int encap_type_attr)
{
const struct lwtunnel_encap_ops *ops;
struct nlattr *nest;
int ret;
if (!lwtstate)
return 0;
if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
lwtstate->type > LWTUNNEL_ENCAP_MAX)
return 0;
nest = nla_nest_start_noflag(skb, encap_attr);
if (!nest)
return -EMSGSIZE;
ret = -EOPNOTSUPP;
rcu_read_lock();
ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
if (likely(ops && ops->fill_encap))
ret = ops->fill_encap(skb, lwtstate);
rcu_read_unlock();
if (ret)
goto nla_put_failure;
nla_nest_end(skb, nest);
ret = nla_put_u16(skb, encap_type_attr, lwtstate->type);
if (ret)
goto nla_put_failure;
return 0;
nla_put_failure:
nla_nest_cancel(skb, nest);
return (ret == -EOPNOTSUPP ? 0 : ret);
}
EXPORT_SYMBOL_GPL(lwtunnel_fill_encap);
int lwtunnel_get_encap_size(struct lwtunnel_state *lwtstate)
{
const struct lwtunnel_encap_ops *ops;
int ret = 0;
if (!lwtstate)
return 0;
if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
lwtstate->type > LWTUNNEL_ENCAP_MAX)
return 0;
rcu_read_lock();
ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
if (likely(ops && ops->get_encap_size))
ret = nla_total_size(ops->get_encap_size(lwtstate));
rcu_read_unlock();
return ret;
}
EXPORT_SYMBOL_GPL(lwtunnel_get_encap_size);
int lwtunnel_cmp_encap(struct lwtunnel_state *a, struct lwtunnel_state *b)
{
const struct lwtunnel_encap_ops *ops;
int ret = 0;
if (!a && !b)
return 0;
if (!a || !b)
return 1;
if (a->type != b->type)
return 1;
if (a->type == LWTUNNEL_ENCAP_NONE ||
a->type > LWTUNNEL_ENCAP_MAX)
return 0;
rcu_read_lock();
ops = rcu_dereference(lwtun_encaps[a->type]);
if (likely(ops && ops->cmp_encap))
ret = ops->cmp_encap(a, b);
rcu_read_unlock();
return ret;
}
EXPORT_SYMBOL_GPL(lwtunnel_cmp_encap);
int lwtunnel_output(struct net *net, struct sock *sk, struct sk_buff *skb)
{
struct dst_entry *dst = skb_dst(skb);
const struct lwtunnel_encap_ops *ops;
struct lwtunnel_state *lwtstate;
int ret = -EINVAL;
if (!dst)
goto drop;
lwtstate = dst->lwtstate;
if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
lwtstate->type > LWTUNNEL_ENCAP_MAX)
return 0;
ret = -EOPNOTSUPP;
rcu_read_lock();
ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
if (likely(ops && ops->output))
ret = ops->output(net, sk, skb);
rcu_read_unlock();
if (ret == -EOPNOTSUPP)
goto drop;
return ret;
drop:
kfree_skb(skb);
return ret;
}
EXPORT_SYMBOL_GPL(lwtunnel_output);
int lwtunnel_xmit(struct sk_buff *skb)
{
struct dst_entry *dst = skb_dst(skb);
const struct lwtunnel_encap_ops *ops;
struct lwtunnel_state *lwtstate;
int ret = -EINVAL;
if (!dst)
goto drop;
lwtstate = dst->lwtstate;
if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
lwtstate->type > LWTUNNEL_ENCAP_MAX)
return 0;
ret = -EOPNOTSUPP;
rcu_read_lock();
ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
if (likely(ops && ops->xmit))
ret = ops->xmit(skb);
rcu_read_unlock();
if (ret == -EOPNOTSUPP)
goto drop;
return ret;
drop:
kfree_skb(skb);
return ret;
}
EXPORT_SYMBOL_GPL(lwtunnel_xmit);
int lwtunnel_input(struct sk_buff *skb)
{
struct dst_entry *dst = skb_dst(skb);
const struct lwtunnel_encap_ops *ops;
struct lwtunnel_state *lwtstate;
int ret = -EINVAL;
if (!dst)
goto drop;
lwtstate = dst->lwtstate;
if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
lwtstate->type > LWTUNNEL_ENCAP_MAX)
return 0;
ret = -EOPNOTSUPP;
rcu_read_lock();
ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
if (likely(ops && ops->input))
ret = ops->input(skb);
rcu_read_unlock();
if (ret == -EOPNOTSUPP)
goto drop;
return ret;
drop:
kfree_skb(skb);
return ret;
}
EXPORT_SYMBOL_GPL(lwtunnel_input);
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