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>

3 files changed, 13 insertions, 12 deletions

diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index f69c8d91dc81..3619c1a12a77 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -26,14 +26,14 @@ static int br_rports_fill_info(struct sk_buff *skb, struct netlink_callback *cb,
 	if (!br->multicast_router || hlist_empty(&br->router_list))
 		return 0;
 
-	nest = nla_nest_start(skb, MDBA_ROUTER);
+	nest = nla_nest_start_noflag(skb, MDBA_ROUTER);
 	if (nest == NULL)
 		return -EMSGSIZE;
 
 	hlist_for_each_entry_rcu(p, &br->router_list, rlist) {
 		if (!p)
 			continue;
-		port_nest = nla_nest_start(skb, MDBA_ROUTER_PORT);
+		port_nest = nla_nest_start_noflag(skb, MDBA_ROUTER_PORT);
 		if (!port_nest)
 			goto fail;
 		if (nla_put_nohdr(skb, sizeof(u32), &p->dev->ifindex) ||
@@ -86,7 +86,7 @@ static int br_mdb_fill_info(struct sk_buff *skb, struct netlink_callback *cb,
 	if (!br_opt_get(br, BROPT_MULTICAST_ENABLED))
 		return 0;
 
-	nest = nla_nest_start(skb, MDBA_MDB);
+	nest = nla_nest_start_noflag(skb, MDBA_MDB);
 	if (nest == NULL)
 		return -EMSGSIZE;
 
@@ -98,7 +98,7 @@ static int br_mdb_fill_info(struct sk_buff *skb, struct netlink_callback *cb,
 		if (idx < s_idx)
 			goto skip;
 
-		nest2 = nla_nest_start(skb, MDBA_MDB_ENTRY);
+		nest2 = nla_nest_start_noflag(skb, MDBA_MDB_ENTRY);
 		if (!nest2) {
 			err = -EMSGSIZE;
 			break;
@@ -124,7 +124,8 @@ static int br_mdb_fill_info(struct sk_buff *skb, struct netlink_callback *cb,
 				e.addr.u.ip6 = p->addr.u.ip6;
 #endif
 			e.addr.proto = p->addr.proto;
-			nest_ent = nla_nest_start(skb, MDBA_MDB_ENTRY_INFO);
+			nest_ent = nla_nest_start_noflag(skb,
+							 MDBA_MDB_ENTRY_INFO);
 			if (!nest_ent) {
 				nla_nest_cancel(skb, nest2);
 				err = -EMSGSIZE;
@@ -248,10 +249,10 @@ static int nlmsg_populate_mdb_fill(struct sk_buff *skb,
 	memset(bpm, 0, sizeof(*bpm));
 	bpm->family  = AF_BRIDGE;
 	bpm->ifindex = dev->ifindex;
-	nest = nla_nest_start(skb, MDBA_MDB);
+	nest = nla_nest_start_noflag(skb, MDBA_MDB);
 	if (nest == NULL)
 		goto cancel;
-	nest2 = nla_nest_start(skb, MDBA_MDB_ENTRY);
+	nest2 = nla_nest_start_noflag(skb, MDBA_MDB_ENTRY);
 	if (nest2 == NULL)
 		goto end;
 
@@ -444,7 +445,7 @@ static int nlmsg_populate_rtr_fill(struct sk_buff *skb,
 	memset(bpm, 0, sizeof(*bpm));
 	bpm->family = AF_BRIDGE;
 	bpm->ifindex = dev->ifindex;
-	nest = nla_nest_start(skb, MDBA_ROUTER);
+	nest = nla_nest_start_noflag(skb, MDBA_ROUTER);
 	if (!nest)
 		goto cancel;
 
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 8dfcc2d285d8..0914477c4719 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -414,7 +414,7 @@ static int br_fill_ifinfo(struct sk_buff *skb,
 
 	if (event == RTM_NEWLINK && port) {
 		struct nlattr *nest
-			= nla_nest_start(skb, IFLA_PROTINFO | NLA_F_NESTED);
+			= nla_nest_start(skb, IFLA_PROTINFO);
 
 		if (nest == NULL || br_port_fill_attrs(skb, port) < 0)
 			goto nla_put_failure;
@@ -439,7 +439,7 @@ static int br_fill_ifinfo(struct sk_buff *skb,
 			rcu_read_unlock();
 			goto done;
 		}
-		af = nla_nest_start(skb, IFLA_AF_SPEC);
+		af = nla_nest_start_noflag(skb, IFLA_AF_SPEC);
 		if (!af) {
 			rcu_read_unlock();
 			goto nla_put_failure;
@@ -1569,7 +1569,7 @@ static int br_fill_linkxstats(struct sk_buff *skb,
 		return -EINVAL;
 	}
 
-	nest = nla_nest_start(skb, LINK_XSTATS_TYPE_BRIDGE);
+	nest = nla_nest_start_noflag(skb, LINK_XSTATS_TYPE_BRIDGE);
 	if (!nest)
 		return -EMSGSIZE;
 
diff --git a/net/bridge/br_netlink_tunnel.c b/net/bridge/br_netlink_tunnel.c
index da8cb99fd259..787e140dc4b5 100644
--- a/net/bridge/br_netlink_tunnel.c
+++ b/net/bridge/br_netlink_tunnel.c
@@ -97,7 +97,7 @@ static int br_fill_vlan_tinfo(struct sk_buff *skb, u16 vid,
 	__be32 tid = tunnel_id_to_key32(tunnel_id);
 	struct nlattr *tmap;
 
-	tmap = nla_nest_start(skb, IFLA_BRIDGE_VLAN_TUNNEL_INFO);
+	tmap = nla_nest_start_noflag(skb, IFLA_BRIDGE_VLAN_TUNNEL_INFO);
 	if (!tmap)
 		return -EMSGSIZE;
 	if (nla_put_u32(skb, IFLA_BRIDGE_VLAN_TUNNEL_ID,