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tcp: Dump bound-only sockets in inet_diag.

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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: Eric Dumazet <edumazet@google.com>
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/b3a84ae61e19c06806eea9c602b3b66e8f0cfc81.1701362867.git.gnault@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Guillaume Nault 2023-12-01 15:49:52 +01:00 committed by Jakub Kicinski
parent e4b5e96d9c
commit 91051f0039
4 changed files with 89 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/tcp_states.h
View File

@ -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 */

1
include/uapi/linux/bpf.h
View File

@ -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! */
};

86
net/ipv4/inet_diag.c
View File

@ -1077,10 +1077,94 @@ skip_listen_ht:
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);

1
net/ipv4/tcp.c
View File

@ -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