Commit 855d8e77 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Alexei Starovoitov
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bpf: af_unix: Use batching algorithm in bpf unix iter. 



The commit 04c7820b ("bpf: tcp: Bpf iter batching and lock_sock")
introduces the batching algorithm to iterate TCP sockets with more
consistency.

This patch uses the same algorithm to iterate AF_UNIX sockets.

Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.co.jp>
Link: https://lore.kernel.org/r/20220113002849.4384-3-kuniyu@amazon.co.jp


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 4408d55a

net/unix/af_unix.c

+177 −7
Original line number Diff line number Diff line
@@ -3356,6 +3356,15 @@ static const struct seq_operations unix_seq_ops = { 
};



#if IS_BUILTIN(CONFIG_UNIX) && defined(CONFIG_BPF_SYSCALL)

struct bpf_unix_iter_state {

	struct seq_net_private p;

	unsigned int cur_sk;

	unsigned int end_sk;

	unsigned int max_sk;

	struct sock **batch;

	bool st_bucket_done;

};



struct bpf_iter__unix {

	__bpf_md_ptr(struct bpf_iter_meta *, meta);

	__bpf_md_ptr(struct unix_sock *, unix_sk);
@@ -3374,24 +3383,156 @@ static int unix_prog_seq_show(struct bpf_prog *prog, struct bpf_iter_meta *meta, 
	return bpf_iter_run_prog(prog, &ctx);

}



static int bpf_iter_unix_hold_batch(struct seq_file *seq, struct sock *start_sk)



{

	struct bpf_unix_iter_state *iter = seq->private;

	unsigned int expected = 1;

	struct sock *sk;



	sock_hold(start_sk);

	iter->batch[iter->end_sk++] = start_sk;



	for (sk = sk_next(start_sk); sk; sk = sk_next(sk)) {

		if (sock_net(sk) != seq_file_net(seq))

			continue;



		if (iter->end_sk < iter->max_sk) {

			sock_hold(sk);

			iter->batch[iter->end_sk++] = sk;

		}



		expected++;

	}



	spin_unlock(&unix_table_locks[start_sk->sk_hash]);



	return expected;

}



static void bpf_iter_unix_put_batch(struct bpf_unix_iter_state *iter)

{

	while (iter->cur_sk < iter->end_sk)

		sock_put(iter->batch[iter->cur_sk++]);

}



static int bpf_iter_unix_realloc_batch(struct bpf_unix_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_unix_put_batch(iter);

	kvfree(iter->batch);

	iter->batch = new_batch;

	iter->max_sk = new_batch_sz;



	return 0;

}



static struct sock *bpf_iter_unix_batch(struct seq_file *seq,

					loff_t *pos)

{

	struct bpf_unix_iter_state *iter = seq->private;

	unsigned int expected;

	bool resized = false;

	struct sock *sk;



	if (iter->st_bucket_done)

		*pos = set_bucket_offset(get_bucket(*pos) + 1, 1);



again:

	/* Get a new batch */

	iter->cur_sk = 0;

	iter->end_sk = 0;



	sk = unix_get_first(seq, pos);

	if (!sk)

		return NULL; /* Done */



	expected = bpf_iter_unix_hold_batch(seq, sk);



	if (iter->end_sk == expected) {

		iter->st_bucket_done = true;

		return sk;

	}



	if (!resized && !bpf_iter_unix_realloc_batch(iter, expected * 3 / 2)) {

		resized = true;

		goto again;

	}



	return sk;

}



static void *bpf_iter_unix_seq_start(struct seq_file *seq, loff_t *pos)

{

	if (!*pos)

		return SEQ_START_TOKEN;



	/* bpf iter does not support lseek, so it always

	 * continue from where it was stop()-ped.

	 */

	return bpf_iter_unix_batch(seq, pos);

}



static void *bpf_iter_unix_seq_next(struct seq_file *seq, void *v, loff_t *pos)

{

	struct bpf_unix_iter_state *iter = seq->private;

	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)

		sock_put(iter->batch[iter->cur_sk++]);



	++*pos;



	if (iter->cur_sk < iter->end_sk)

		sk = iter->batch[iter->cur_sk];

	else

		sk = bpf_iter_unix_batch(seq, pos);



	return sk;

}



static int bpf_iter_unix_seq_show(struct seq_file *seq, void *v)

{

	struct bpf_iter_meta meta;

	struct bpf_prog *prog;

	struct sock *sk = v;

	uid_t uid;

	bool slow;

	int ret;



	if (v == SEQ_START_TOKEN)

		return 0;



	slow = lock_sock_fast(sk);



	if (unlikely(sk_unhashed(sk))) {

		ret = SEQ_SKIP;

		goto unlock;

	}



	uid = from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk));

	meta.seq = seq;

	prog = bpf_iter_get_info(&meta, false);

	return unix_prog_seq_show(prog, &meta, v, uid);

	ret = unix_prog_seq_show(prog, &meta, v, uid);

unlock:

	unlock_sock_fast(sk, slow);

	return ret;

}



static void bpf_iter_unix_seq_stop(struct seq_file *seq, void *v)

{

	struct bpf_unix_iter_state *iter = seq->private;

	struct bpf_iter_meta meta;

	struct bpf_prog *prog;
@@ -3402,12 +3543,13 @@ static void bpf_iter_unix_seq_stop(struct seq_file *seq, void *v) 
			(void)unix_prog_seq_show(prog, &meta, v, 0);

	}



	unix_seq_stop(seq, v);

	if (iter->cur_sk < iter->end_sk)

		bpf_iter_unix_put_batch(iter);

}



static const struct seq_operations bpf_iter_unix_seq_ops = {

	.start	= unix_seq_start,

	.next	= unix_seq_next,

	.start	= bpf_iter_unix_seq_start,

	.next	= bpf_iter_unix_seq_next,

	.stop	= bpf_iter_unix_seq_stop,

	.show	= bpf_iter_unix_seq_show,

};
@@ -3456,11 +3598,39 @@ static struct pernet_operations unix_net_ops = { 
DEFINE_BPF_ITER_FUNC(unix, struct bpf_iter_meta *meta,

		     struct unix_sock *unix_sk, uid_t uid)



#define INIT_BATCH_SZ 16



static int bpf_iter_init_unix(void *priv_data, struct bpf_iter_aux_info *aux)

{

	struct bpf_unix_iter_state *iter = priv_data;

	int err;



	err = bpf_iter_init_seq_net(priv_data, aux);

	if (err)

		return err;



	err = bpf_iter_unix_realloc_batch(iter, INIT_BATCH_SZ);

	if (err) {

		bpf_iter_fini_seq_net(priv_data);

		return err;

	}



	return 0;

}



static void bpf_iter_fini_unix(void *priv_data)

{

	struct bpf_unix_iter_state *iter = priv_data;



	bpf_iter_fini_seq_net(priv_data);

	kvfree(iter->batch);

}



static const struct bpf_iter_seq_info unix_seq_info = {

	.seq_ops		= &bpf_iter_unix_seq_ops,

	.init_seq_private	= bpf_iter_init_seq_net,

	.fini_seq_private	= bpf_iter_fini_seq_net,

	.seq_priv_size		= sizeof(struct seq_net_private),

	.init_seq_private	= bpf_iter_init_unix,

	.fini_seq_private	= bpf_iter_fini_unix,

	.seq_priv_size		= sizeof(struct bpf_unix_iter_state),

};



static struct bpf_iter_reg unix_reg_info = {