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linux/net/core/lwtunnel.c
Michal Kubecek ae0be8de9a netlink: make nla_nest_start() add NLA_F_NESTED flag 
Even if the NLA_F_NESTED flag was introduced more than 11 years ago, most
netlink based interfaces (including recently added ones) are still not
setting it in kernel generated messages. Without the flag, message parsers
not aware of attribute semantics (e.g. wireshark dissector or libmnl's
mnl_nlmsg_fprintf()) cannot recognize nested attributes and won't display
the structure of their contents.

Unfortunately we cannot just add the flag everywhere as there may be
userspace applications which check nlattr::nla_type directly rather than
through a helper masking out the flags. Therefore the patch renames
nla_nest_start() to nla_nest_start_noflag() and introduces nla_nest_start()
as a wrapper adding NLA_F_NESTED. The calls which add NLA_F_NESTED manually
are rewritten to use nla_nest_start().

Except for changes in include/net/netlink.h, the patch was generated using
this semantic patch:

@@ expression E1, E2; @@
-nla_nest_start(E1, E2)
+nla_nest_start_noflag(E1, E2)

@@ expression E1, E2; @@
-nla_nest_start_noflag(E1, E2 | NLA_F_NESTED)
+nla_nest_start(E1, E2)

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-04-27 17:03:44 -04:00

419 lines
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/*
* lwtunnel Infrastructure for light weight tunnels like mpls
*
* Authors: Roopa Prabhu, <roopa@cumulusnetworks.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*/
#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>
#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_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(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(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) {
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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