inet_diag: Refactor inet_sk_diag_fill(), dump(), and dump_one()

In a latter patch, there is a need to update "cb->min_dump_alloc"
in inet_sk_diag_fill() as it learns the diffierent bpf_sk_storages
stored in a sk while dumping all sk(s) (e.g. tcp_hashinfo).

The inet_sk_diag_fill() currently does not take the "cb" as an argument.
One of the reason is inet_sk_diag_fill() is used by both dump_one()
and dump() (which belong to the "struct inet_diag_handler".  The dump_one()
interface does not pass the "cb" along.

This patch is to make dump_one() pass a "cb".  The "cb" is created in
inet_diag_cmd_exact().  The "nlh" and "in_skb" are stored in "cb" as
the dump() interface does.  The total number of args in
inet_sk_diag_fill() is also cut from 10 to 7 and
that helps many callers to pass fewer args.

In particular,
"struct user_namespace *user_ns", "u32 pid", and "u32 seq"
can be replaced by accessing "cb->nlh" and "cb->skb".

A similar argument reduction is also made to
inet_twsk_diag_fill() and inet_req_diag_fill().

inet_csk_diag_dump() and inet_csk_diag_fill() are also removed.
They are mostly equivalent to inet_sk_diag_fill().  Their repeated
usages are very limited.  Thus, inet_sk_diag_fill() is directly used
in those occasions.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200225230409.1975173-1-kafai@fb.com

1 files changed, 11 insertions, 15 deletions

diff --git a/net/ipv4/udp_diag.c b/net/ipv4/udp_diag.c
index 910555a4d9fe..7d65a6a5cd51 100644
--- a/net/ipv4/udp_diag.c
+++ b/net/ipv4/udp_diag.c
@@ -21,16 +21,15 @@ static int sk_diag_dump(struct sock *sk, struct sk_buff *skb,
 	if (!inet_diag_bc_sk(bc, sk))
 		return 0;
 
-	return inet_sk_diag_fill(sk, NULL, skb, req,
-			sk_user_ns(NETLINK_CB(cb->skb).sk),
-			NETLINK_CB(cb->skb).portid,
-			cb->nlh->nlmsg_seq, NLM_F_MULTI, cb->nlh, net_admin);
+	return inet_sk_diag_fill(sk, NULL, skb, cb, req, NLM_F_MULTI,
+				 net_admin);
 }
 
-static int udp_dump_one(struct udp_table *tbl, struct sk_buff *in_skb,
-			const struct nlmsghdr *nlh,
+static int udp_dump_one(struct udp_table *tbl,
+			struct netlink_callback *cb,
 			const struct inet_diag_req_v2 *req)
 {
+	struct sk_buff *in_skb = cb->skb;
 	int err = -EINVAL;
 	struct sock *sk = NULL;
 	struct sk_buff *rep;
@@ -70,11 +69,8 @@ static int udp_dump_one(struct udp_table *tbl, struct sk_buff *in_skb,
 	if (!rep)
 		goto out;
 
-	err = inet_sk_diag_fill(sk, NULL, rep, req,
-			   sk_user_ns(NETLINK_CB(in_skb).sk),
-			   NETLINK_CB(in_skb).portid,
-			   nlh->nlmsg_seq, 0, nlh,
-			   netlink_net_capable(in_skb, CAP_NET_ADMIN));
+	err = inet_sk_diag_fill(sk, NULL, rep, cb, req, 0,
+				netlink_net_capable(in_skb, CAP_NET_ADMIN));
 	if (err < 0) {
 		WARN_ON(err == -EMSGSIZE);
 		kfree_skb(rep);
@@ -151,10 +147,10 @@ static void udp_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
 	udp_dump(&udp_table, skb, cb, r, bc);
 }
 
-static int udp_diag_dump_one(struct sk_buff *in_skb, const struct nlmsghdr *nlh,
+static int udp_diag_dump_one(struct netlink_callback *cb,
 			     const struct inet_diag_req_v2 *req)
 {
-	return udp_dump_one(&udp_table, in_skb, nlh, req);
+	return udp_dump_one(&udp_table, cb, req);
 }
 
 static void udp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
@@ -255,10 +251,10 @@ static void udplite_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
 	udp_dump(&udplite_table, skb, cb, r, bc);
 }
 
-static int udplite_diag_dump_one(struct sk_buff *in_skb, const struct nlmsghdr *nlh,
+static int udplite_diag_dump_one(struct netlink_callback *cb,
 				 const struct inet_diag_req_v2 *req)
 {
-	return udp_dump_one(&udplite_table, in_skb, nlh, req);
+	return udp_dump_one(&udplite_table, cb, req);
 }
 
 static const struct inet_diag_handler udplite_diag_handler = {