1 files changed, 231 insertions, 6 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index d38b4379dca4..84ac0135d389 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2687,6 +2687,15 @@ out:
 }
 
 #ifdef CONFIG_BPF_SYSCALL
+struct bpf_tcp_iter_state {
+	struct tcp_iter_state state;
+	unsigned int cur_sk;
+	unsigned int end_sk;
+	unsigned int max_sk;
+	struct sock **batch;
+	bool st_bucket_done;
+};
+
 struct bpf_iter__tcp {
 	__bpf_md_ptr(struct bpf_iter_meta *, meta);
 	__bpf_md_ptr(struct sock_common *, sk_common);
@@ -2705,16 +2714,204 @@ static int tcp_prog_seq_show(struct bpf_prog *prog, struct bpf_iter_meta *meta,
 	return bpf_iter_run_prog(prog, &ctx);
 }
 
+static void bpf_iter_tcp_put_batch(struct bpf_tcp_iter_state *iter)
+{
+	while (iter->cur_sk < iter->end_sk)
+		sock_put(iter->batch[iter->cur_sk++]);
+}
+
+static int bpf_iter_tcp_realloc_batch(struct bpf_tcp_iter_state *iter,
+				      unsigned int new_batch_sz)
+{
+	struct sock **new_batch;
+
+	new_batch = kvmalloc(sizeof(*new_batch) * new_batch_sz,
+			     GFP_USER | __GFP_NOWARN);
+	if (!new_batch)
+		return -ENOMEM;
+
+	bpf_iter_tcp_put_batch(iter);
+	kvfree(iter->batch);
+	iter->batch = new_batch;
+	iter->max_sk = new_batch_sz;
+
+	return 0;
+}
+
+static unsigned int bpf_iter_tcp_listening_batch(struct seq_file *seq,
+						 struct sock *start_sk)
+{
+	struct bpf_tcp_iter_state *iter = seq->private;
+	struct tcp_iter_state *st = &iter->state;
+	struct inet_connection_sock *icsk;
+	unsigned int expected = 1;
+	struct sock *sk;
+
+	sock_hold(start_sk);
+	iter->batch[iter->end_sk++] = start_sk;
+
+	icsk = inet_csk(start_sk);
+	inet_lhash2_for_each_icsk_continue(icsk) {
+		sk = (struct sock *)icsk;
+		if (seq_sk_match(seq, sk)) {
+			if (iter->end_sk < iter->max_sk) {
+				sock_hold(sk);
+				iter->batch[iter->end_sk++] = sk;
+			}
+			expected++;
+		}
+	}
+	spin_unlock(&tcp_hashinfo.lhash2[st->bucket].lock);
+
+	return expected;
+}
+
+static unsigned int bpf_iter_tcp_established_batch(struct seq_file *seq,
+						   struct sock *start_sk)
+{
+	struct bpf_tcp_iter_state *iter = seq->private;
+	struct tcp_iter_state *st = &iter->state;
+	struct hlist_nulls_node *node;
+	unsigned int expected = 1;
+	struct sock *sk;
+
+	sock_hold(start_sk);
+	iter->batch[iter->end_sk++] = start_sk;
+
+	sk = sk_nulls_next(start_sk);
+	sk_nulls_for_each_from(sk, node) {
+		if (seq_sk_match(seq, sk)) {
+			if (iter->end_sk < iter->max_sk) {
+				sock_hold(sk);
+				iter->batch[iter->end_sk++] = sk;
+			}
+			expected++;
+		}
+	}
+	spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
+
+	return expected;
+}
+
+static struct sock *bpf_iter_tcp_batch(struct seq_file *seq)
+{
+	struct bpf_tcp_iter_state *iter = seq->private;
+	struct tcp_iter_state *st = &iter->state;
+	unsigned int expected;
+	bool resized = false;
+	struct sock *sk;
+
+	/* The st->bucket is done.  Directly advance to the next
+	 * bucket instead of having the tcp_seek_last_pos() to skip
+	 * one by one in the current bucket and eventually find out
+	 * it has to advance to the next bucket.
+	 */
+	if (iter->st_bucket_done) {
+		st->offset = 0;
+		st->bucket++;
+		if (st->state == TCP_SEQ_STATE_LISTENING &&
+		    st->bucket > tcp_hashinfo.lhash2_mask) {
+			st->state = TCP_SEQ_STATE_ESTABLISHED;
+			st->bucket = 0;
+		}
+	}
+
+again:
+	/* Get a new batch */
+	iter->cur_sk = 0;
+	iter->end_sk = 0;
+	iter->st_bucket_done = false;
+
+	sk = tcp_seek_last_pos(seq);
+	if (!sk)
+		return NULL; /* Done */
+
+	if (st->state == TCP_SEQ_STATE_LISTENING)
+		expected = bpf_iter_tcp_listening_batch(seq, sk);
+	else
+		expected = bpf_iter_tcp_established_batch(seq, sk);
+
+	if (iter->end_sk == expected) {
+		iter->st_bucket_done = true;
+		return sk;
+	}
+
+	if (!resized && !bpf_iter_tcp_realloc_batch(iter, expected * 3 / 2)) {
+		resized = true;
+		goto again;
+	}
+
+	return sk;
+}
+
+static void *bpf_iter_tcp_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	/* bpf iter does not support lseek, so it always
+	 * continue from where it was stop()-ped.
+	 */
+	if (*pos)
+		return bpf_iter_tcp_batch(seq);
+
+	return SEQ_START_TOKEN;
+}
+
+static void *bpf_iter_tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct bpf_tcp_iter_state *iter = seq->private;
+	struct tcp_iter_state *st = &iter->state;
+	struct sock *sk;
+
+	/* Whenever seq_next() is called, the iter->cur_sk is
+	 * done with seq_show(), so advance to the next sk in
+	 * the batch.
+	 */
+	if (iter->cur_sk < iter->end_sk) {
+		/* Keeping st->num consistent in tcp_iter_state.
+		 * bpf_iter_tcp does not use st->num.
+		 * meta.seq_num is used instead.
+		 */
+		st->num++;
+		/* Move st->offset to the next sk in the bucket such that
+		 * the future start() will resume at st->offset in
+		 * st->bucket.  See tcp_seek_last_pos().
+		 */
+		st->offset++;
+		sock_put(iter->batch[iter->cur_sk++]);
+	}
+
+	if (iter->cur_sk < iter->end_sk)
+		sk = iter->batch[iter->cur_sk];
+	else
+		sk = bpf_iter_tcp_batch(seq);
+
+	++*pos;
+	/* Keeping st->last_pos consistent in tcp_iter_state.
+	 * bpf iter does not do lseek, so st->last_pos always equals to *pos.
+	 */
+	st->last_pos = *pos;
+	return sk;
+}
+
 static int bpf_iter_tcp_seq_show(struct seq_file *seq, void *v)
 {
 	struct bpf_iter_meta meta;
 	struct bpf_prog *prog;
 	struct sock *sk = v;
+	bool slow;
 	uid_t uid;
+	int ret;
 
 	if (v == SEQ_START_TOKEN)
 		return 0;
 
+	if (sk_fullsock(sk))
+		slow = lock_sock_fast(sk);
+
+	if (unlikely(sk_unhashed(sk))) {
+		ret = SEQ_SKIP;
+		goto unlock;
+	}
+
 	if (sk->sk_state == TCP_TIME_WAIT) {
 		uid = 0;
 	} else if (sk->sk_state == TCP_NEW_SYN_RECV) {
@@ -2728,11 +2925,18 @@ static int bpf_iter_tcp_seq_show(struct seq_file *seq, void *v)
 
 	meta.seq = seq;
 	prog = bpf_iter_get_info(&meta, false);
-	return tcp_prog_seq_show(prog, &meta, v, uid);
+	ret = tcp_prog_seq_show(prog, &meta, v, uid);
+
+unlock:
+	if (sk_fullsock(sk))
+		unlock_sock_fast(sk, slow);
+	return ret;
+
 }
 
 static void bpf_iter_tcp_seq_stop(struct seq_file *seq, void *v)
 {
+	struct bpf_tcp_iter_state *iter = seq->private;
 	struct bpf_iter_meta meta;
 	struct bpf_prog *prog;
 
@@ -2743,13 +2947,16 @@ static void bpf_iter_tcp_seq_stop(struct seq_file *seq, void *v)
 			(void)tcp_prog_seq_show(prog, &meta, v, 0);
 	}
 
-	tcp_seq_stop(seq, v);
+	if (iter->cur_sk < iter->end_sk) {
+		bpf_iter_tcp_put_batch(iter);
+		iter->st_bucket_done = false;
+	}
 }
 
 static const struct seq_operations bpf_iter_tcp_seq_ops = {
 	.show		= bpf_iter_tcp_seq_show,
-	.start		= tcp_seq_start,
-	.next		= tcp_seq_next,
+	.start		= bpf_iter_tcp_seq_start,
+	.next		= bpf_iter_tcp_seq_next,
 	.stop		= bpf_iter_tcp_seq_stop,
 };
 #endif
@@ -3017,21 +3224,39 @@ static struct pernet_operations __net_initdata tcp_sk_ops = {
 DEFINE_BPF_ITER_FUNC(tcp, struct bpf_iter_meta *meta,
 		     struct sock_common *sk_common, uid_t uid)
 
+#define INIT_BATCH_SZ 16
+
 static int bpf_iter_init_tcp(void *priv_data, struct bpf_iter_aux_info *aux)
 {
-	return bpf_iter_init_seq_net(priv_data, aux);
+	struct bpf_tcp_iter_state *iter = priv_data;
+	int err;
+
+	err = bpf_iter_init_seq_net(priv_data, aux);
+	if (err)
+		return err;
+
+	err = bpf_iter_tcp_realloc_batch(iter, INIT_BATCH_SZ);
+	if (err) {
+		bpf_iter_fini_seq_net(priv_data);
+		return err;
+	}
+
+	return 0;
 }
 
 static void bpf_iter_fini_tcp(void *priv_data)
 {
+	struct bpf_tcp_iter_state *iter = priv_data;
+
 	bpf_iter_fini_seq_net(priv_data);
+	kvfree(iter->batch);
 }
 
 static const struct bpf_iter_seq_info tcp_seq_info = {
 	.seq_ops		= &bpf_iter_tcp_seq_ops,
 	.init_seq_private	= bpf_iter_init_tcp,
 	.fini_seq_private	= bpf_iter_fini_tcp,
-	.seq_priv_size		= sizeof(struct tcp_iter_state),
+	.seq_priv_size		= sizeof(struct bpf_tcp_iter_state),
 };
 
 static struct bpf_iter_reg tcp_reg_info = {