[PATCH 4.16 09/64] udp: fix rx queue len reported by diag and proc interface

Greg Kroah-Hartman
2018-06-24T15:34:42Z

From: Paolo Abeni <pabeni@redhat.com>

[ Upstream commit 6c206b20092a3623184cff9470dba75d21507874 ]

After commit 6b229cf77d68 ("udp: add batching to udp_rmem_release()")
the sk_rmem_alloc field does not measure exactly anymore the
receive queue length, because we batch the rmem release. The issue
is really apparent only after commit 0d4a6608f68c ("udp: do rmem bulk
free even if the rx sk queue is empty"): the user space can easily
check for an empty socket with not-0 queue length reported by the 'ss'
tool or the procfs interface.

We need to use a custom UDP helper to report the correct queue length,
taking into account the forward allocation deficit.

Reported-by: trevor.francis@46labs.com
Fixes: 6b229cf77d68 ("UDP: add batching to udp_rmem_release()")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/net/transp_v6.h | 11 +++++++++--
include/net/udp.h | 5 +++++
net/ipv4/udp.c | 2 +-
net/ipv4/udp_diag.c | 2 +-
net/ipv6/datagram.c | 6 +++---
net/ipv6/udp.c | 3 ++-
6 files changed, 21 insertions(+), 8 deletions(-)

--- a/include/net/transp_v6.h
+++ b/include/net/transp_v6.h
@@ -45,8 +45,15 @@ int ip6_datagram_send_ctl(struct net *ne
struct flowi6 *fl6, struct ipcm6_cookie *ipc6,
struct sockcm_cookie *sockc);

-void ip6_dgram_sock_seq_show(struct seq_file *seq, struct sock *sp,
- __u16 srcp, __u16 destp, int bucket);
+void __ip6_dgram_sock_seq_show(struct seq_file *seq, struct sock *sp,
+ __u16 srcp, __u16 destp, int rqueue, int bucket);
+static inline void
+ip6_dgram_sock_seq_show(struct seq_file *seq, struct sock *sp, __u16 srcp,
+ __u16 destp, int bucket)
+{
+ __ip6_dgram_sock_seq_show(seq, sp, srcp, destp, sk_rmem_alloc_get(sp),
+ bucket);
+}

#define LOOPBACK4_IPV6 cpu_to_be32(0x7f000006)

--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -244,6 +244,11 @@ static inline __be16 udp_flow_src_port(s
return htons((((u64) hash * (max - min)) >> 32) + min);
}

+static inline int udp_rqueue_get(struct sock *sk)
+{
+ return sk_rmem_alloc_get(sk) - READ_ONCE(udp_sk(sk)->forward_deficit);
+}
+
/* net/ipv4/udp.c */
void udp_destruct_sock(struct sock *sk);
void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len);
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2710,7 +2710,7 @@ static void udp4_format_sock(struct sock
" %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d",
bucket, src, srcp, dest, destp, sp->sk_state,
sk_wmem_alloc_get(sp),
- sk_rmem_alloc_get(sp),
+ udp_rqueue_get(sp),
0, 0L, 0,
from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
0, sock_i_ino(sp),
--- a/net/ipv4/udp_diag.c
+++ b/net/ipv4/udp_diag.c
@@ -163,7 +163,7 @@ static int udp_diag_dump_one(struct sk_b
static void udp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
void *info)
{
- r->idiag_rqueue = sk_rmem_alloc_get(sk);
+ r->idiag_rqueue = udp_rqueue_get(sk);
r->idiag_wqueue = sk_wmem_alloc_get(sk);
}

--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -1025,8 +1025,8 @@ exit_f:
}
EXPORT_SYMBOL_GPL(ip6_datagram_send_ctl);

-void ip6_dgram_sock_seq_show(struct seq_file *seq, struct sock *sp,
- __u16 srcp, __u16 destp, int bucket)
+void __ip6_dgram_sock_seq_show(struct seq_file *seq, struct sock *sp,
+ __u16 srcp, __u16 destp, int rqueue, int bucket)
{
const struct in6_addr *dest, *src;

@@ -1042,7 +1042,7 @@ void ip6_dgram_sock_seq_show(struct seq_
dest->s6_addr32[2], dest->s6_addr32[3], destp,
sp->sk_state,
sk_wmem_alloc_get(sp),
- sk_rmem_alloc_get(sp),
+ rqueue,
0, 0L, 0,
from_kuid_munged(seq_user_ns(seq), sock_i_uid(sp)),
0,
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1473,7 +1473,8 @@ int udp6_seq_show(struct seq_file *seq,
struct inet_sock *inet = inet_sk(v);
__u16 srcp = ntohs(inet->inet_sport);
__u16 destp = ntohs(inet->inet_dport);
- ip6_dgram_sock_seq_show(seq, v, srcp, destp, bucket);
+ __ip6_dgram_sock_seq_show(seq, v, srcp, destp,
+ udp_rqueue_get(v), bucket);
}
return 0;
}