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>

1 files changed, 7 insertions, 7 deletions

diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 5a87e271d35a..641ad7575f24 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -242,7 +242,7 @@ static int tcf_dump_walker(struct tcf_idrinfo *idrinfo, struct sk_buff *skb,
 			       (unsigned long)p->tcfa_tm.lastuse))
 			continue;
 
-		nest = nla_nest_start(skb, n_i);
+		nest = nla_nest_start_noflag(skb, n_i);
 		if (!nest) {
 			index--;
 			goto nla_put_failure;
@@ -299,7 +299,7 @@ static int tcf_del_walker(struct tcf_idrinfo *idrinfo, struct sk_buff *skb,
 	struct tc_action *p;
 	unsigned long id = 1;
 
-	nest = nla_nest_start(skb, 0);
+	nest = nla_nest_start_noflag(skb, 0);
 	if (nest == NULL)
 		goto nla_put_failure;
 	if (nla_put_string(skb, TCA_KIND, ops->kind))
@@ -776,7 +776,7 @@ tcf_action_dump_1(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
 	}
 	rcu_read_unlock();
 
-	nest = nla_nest_start(skb, TCA_OPTIONS);
+	nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
 	if (nest == NULL)
 		goto nla_put_failure;
 	err = tcf_action_dump_old(skb, a, bind, ref);
@@ -800,7 +800,7 @@ int tcf_action_dump(struct sk_buff *skb, struct tc_action *actions[],
 
 	for (i = 0; i < TCA_ACT_MAX_PRIO && actions[i]; i++) {
 		a = actions[i];
-		nest = nla_nest_start(skb, a->order);
+		nest = nla_nest_start_noflag(skb, a->order);
 		if (nest == NULL)
 			goto nla_put_failure;
 		err = tcf_action_dump_1(skb, a, bind, ref);
@@ -1052,7 +1052,7 @@ static int tca_get_fill(struct sk_buff *skb, struct tc_action *actions[],
 	t->tca__pad1 = 0;
 	t->tca__pad2 = 0;
 
-	nest = nla_nest_start(skb, TCA_ACT_TAB);
+	nest = nla_nest_start_noflag(skb, TCA_ACT_TAB);
 	if (!nest)
 		goto out_nlmsg_trim;
 
@@ -1176,7 +1176,7 @@ static int tca_action_flush(struct net *net, struct nlattr *nla,
 	t->tca__pad1 = 0;
 	t->tca__pad2 = 0;
 
-	nest = nla_nest_start(skb, TCA_ACT_TAB);
+	nest = nla_nest_start_noflag(skb, TCA_ACT_TAB);
 	if (!nest) {
 		NL_SET_ERR_MSG(extack, "Failed to add new netlink message");
 		goto out_module_put;
@@ -1508,7 +1508,7 @@ static int tc_dump_action(struct sk_buff *skb, struct netlink_callback *cb)
 	if (!count_attr)
 		goto out_module_put;
 
-	nest = nla_nest_start(skb, TCA_ACT_TAB);
+	nest = nla_nest_start_noflag(skb, TCA_ACT_TAB);
 	if (nest == NULL)
 		goto out_module_put;