Commit 91051f00 authored by Guillaume Nault's avatar Guillaume Nault Committed by Jakub Kicinski
Browse files

tcp: Dump bound-only sockets in inet_diag. 



Walk the hashinfo->bhash2 table so that inet_diag can dump TCP sockets
that are bound but haven't yet called connect() or listen().

The code is inspired by the ->lhash2 loop. However there's no manual
test of the source port, since this kind of filtering is already
handled by inet_diag_bc_sk(). Also, a maximum of 16 sockets are dumped
at a time, to avoid running with bh disabled for too long.

There's no TCP state for bound but otherwise inactive sockets. Such
sockets normally map to TCP_CLOSE. However, "ss -l", which is supposed
to only dump listening sockets, actually requests the kernel to dump
sockets in either the TCP_LISTEN or TCP_CLOSE states. To avoid dumping
bound-only sockets with "ss -l", we therefore need to define a new
pseudo-state (TCP_BOUND_INACTIVE) that user space will be able to set
explicitly.

With an IPv4, an IPv6 and an IPv6-only socket, bound respectively to
40000, 64000, 60000, an updated version of iproute2 could work as
follow:

  $ ss -t state bound-inactive
  Recv-Q   Send-Q     Local Address:Port       Peer Address:Port   Process
  0        0                0.0.0.0:40000           0.0.0.0:*
  0        0                   [::]:60000              [::]:*
  0        0                      *:64000                 *:*

Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarGuillaume Nault <gnault@redhat.com>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/b3a84ae61e19c06806eea9c602b3b66e8f0cfc81.1701362867.git.gnault@redhat.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent e4b5e96d

include/net/tcp_states.h

+2 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ enum { 
	TCP_LISTEN,

	TCP_CLOSING,	/* Now a valid state */

	TCP_NEW_SYN_RECV,

	TCP_BOUND_INACTIVE, /* Pseudo-state for inet_diag */



	TCP_MAX_STATES	/* Leave at the end! */

};
@@ -43,6 +44,7 @@ enum { 
	TCPF_LISTEN	 = (1 << TCP_LISTEN),

	TCPF_CLOSING	 = (1 << TCP_CLOSING),

	TCPF_NEW_SYN_RECV = (1 << TCP_NEW_SYN_RECV),

	TCPF_BOUND_INACTIVE = (1 << TCP_BOUND_INACTIVE),

};



#endif	/* _LINUX_TCP_STATES_H */

include/uapi/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -6902,6 +6902,7 @@ enum { 
	BPF_TCP_LISTEN,

	BPF_TCP_CLOSING,	/* Now a valid state */

	BPF_TCP_NEW_SYN_RECV,

	BPF_TCP_BOUND_INACTIVE,



	BPF_TCP_MAX_STATES	/* Leave at the end! */

};

net/ipv4/inet_diag.c

+85 −1
Original line number Diff line number Diff line
@@ -1077,10 +1077,94 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb, 
		s_i = num = s_num = 0;

	}



/* Process a maximum of SKARR_SZ sockets at a time when walking hash buckets

 * with bh disabled.

 */

#define SKARR_SZ 16



	/* Dump bound but inactive (not listening, connecting, etc.) sockets */

	if (cb->args[0] == 1) {

		if (!(idiag_states & TCPF_BOUND_INACTIVE))

			goto skip_bind_ht;



		for (i = s_i; i < hashinfo->bhash_size; i++) {

			struct inet_bind_hashbucket *ibb;

			struct inet_bind2_bucket *tb2;

			struct sock *sk_arr[SKARR_SZ];

			int num_arr[SKARR_SZ];

			int idx, accum, res;



resume_bind_walk:

			num = 0;

			accum = 0;

			ibb = &hashinfo->bhash2[i];



			spin_lock_bh(&ibb->lock);

			inet_bind_bucket_for_each(tb2, &ibb->chain) {

				if (!net_eq(ib2_net(tb2), net))

					continue;



				sk_for_each_bound_bhash2(sk, &tb2->owners) {

					struct inet_sock *inet = inet_sk(sk);



					if (num < s_num)

						goto next_bind;



					if (sk->sk_state != TCP_CLOSE ||

					    !inet->inet_num)

						goto next_bind;



					if (r->sdiag_family != AF_UNSPEC &&

					    r->sdiag_family != sk->sk_family)

						goto next_bind;



					if (!inet_diag_bc_sk(bc, sk))

						goto next_bind;



					sock_hold(sk);

					num_arr[accum] = num;

					sk_arr[accum] = sk;

					if (++accum == SKARR_SZ)

						goto pause_bind_walk;

next_bind:

					num++;

				}

			}

pause_bind_walk:

			spin_unlock_bh(&ibb->lock);



			res = 0;

			for (idx = 0; idx < accum; idx++) {

				if (res >= 0) {

					res = inet_sk_diag_fill(sk_arr[idx],

								NULL, skb, cb,

								r, NLM_F_MULTI,

								net_admin);

					if (res < 0)

						num = num_arr[idx];

				}

				sock_put(sk_arr[idx]);

			}

			if (res < 0)

				goto done;



			cond_resched();



			if (accum == SKARR_SZ) {

				s_num = num + 1;

				goto resume_bind_walk;

			}



			s_num = 0;

		}

skip_bind_ht:

		cb->args[0] = 2;

		s_i = num = s_num = 0;

	}



	if (!(idiag_states & ~TCPF_LISTEN))

		goto out;



#define SKARR_SZ 16

	for (i = s_i; i <= hashinfo->ehash_mask; i++) {

		struct inet_ehash_bucket *head = &hashinfo->ehash[i];

		spinlock_t *lock = inet_ehash_lockp(hashinfo, i);

net/ipv4/tcp.c

+1 −0
Original line number Diff line number Diff line
@@ -2605,6 +2605,7 @@ void tcp_set_state(struct sock *sk, int state) 
	BUILD_BUG_ON((int)BPF_TCP_LISTEN != (int)TCP_LISTEN);

	BUILD_BUG_ON((int)BPF_TCP_CLOSING != (int)TCP_CLOSING);

	BUILD_BUG_ON((int)BPF_TCP_NEW_SYN_RECV != (int)TCP_NEW_SYN_RECV);

	BUILD_BUG_ON((int)BPF_TCP_BOUND_INACTIVE != (int)TCP_BOUND_INACTIVE);

	BUILD_BUG_ON((int)BPF_TCP_MAX_STATES != (int)TCP_MAX_STATES);



	/* bpf uapi header bpf.h defines an anonymous enum with values