[PATCH] Revert "net: do not allow changing SO_REUSEADDR/SO_REUSEPORT on bound sockets"

[Bart Van Assche]

Revert the patch mentioned in the subject because it breaks at least
the Avahi mDNS daemon. That patch namely causes the Ubuntu 18.04 Avahi
daemon to fail to start:

Jun 12 09:49:24 ubuntu-vm avahi-daemon[529]: Successfully called chroot().
Jun 12 09:49:24 ubuntu-vm avahi-daemon[529]: Successfully dropped remaining 
capabilities.
Jun 12 09:49:24 ubuntu-vm avahi-daemon[529]: No service file found in 
/etc/avahi/services.
Jun 12 09:49:24 ubuntu-vm avahi-daemon[529]: SO_REUSEADDR failed: Structure 
needs cleaning
Jun 12 09:49:24 ubuntu-vm avahi-daemon[529]: SO_REUSEADDR failed: Structure 
needs cleaning
Jun 12 09:49:24 ubuntu-vm avahi-daemon[529]: Failed to create server: No 
suitable network protocol available
Jun 12 09:49:24 ubuntu-vm avahi-daemon[529]: avahi-daemon 0.7 exiting.
Jun 12 09:49:24 ubuntu-vm systemd[1]: avahi-daemon.service: Main process 
exited, code=exited, status=255/n/a
Jun 12 09:49:24 ubuntu-vm systemd[1]: avahi-daemon.service: Failed with result 
'exit-code'.
Jun 12 09:49:24 ubuntu-vm systemd[1]: Failed to start Avahi mDNS/DNS-SD Stack.

Fixes: f396922d862a ("net: do not allow changing SO_REUSEADDR/SO_REUSEPORT on 
bound sockets")
Cc: Maciej Żenczykowski <m...@google.com>
Cc: Eric Dumazet <eduma...@google.com>
Signed-off-by: Bart Van Assche <bart.vanass...@wdc.com>
---
 net/core/sock.c | 15 +--------------
 1 file changed, 1 insertion(+), 14 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index f333d75ef1a9..bcc41829a16d 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -728,22 +728,9 @@ int sock_setsockopt(struct socket *sock, int level, int 
optname,
                        sock_valbool_flag(sk, SOCK_DBG, valbool);
                break;
        case SO_REUSEADDR:
-               val = (valbool ? SK_CAN_REUSE : SK_NO_REUSE);
-               if ((sk->sk_family == PF_INET || sk->sk_family == PF_INET6) &&
-                   inet_sk(sk)->inet_num &&
-                   (sk->sk_reuse != val)) {
-                       ret = (sk->sk_state == TCP_ESTABLISHED) ? -EISCONN : 
-EUCLEAN;
-                       break;
-               }
-               sk->sk_reuse = val;
+               sk->sk_reuse = (valbool ? SK_CAN_REUSE : SK_NO_REUSE);
                break;
        case SO_REUSEPORT:
-               if ((sk->sk_family == PF_INET || sk->sk_family == PF_INET6) &&
-                   inet_sk(sk)->inet_num &&
-                   (sk->sk_reuseport != valbool)) {
-                       ret = (sk->sk_state == TCP_ESTABLISHED) ? -EISCONN : 
-EUCLEAN;
-                       break;
-               }
                sk->sk_reuseport = valbool;
                break;
        case SO_TYPE:
-- 
2.17.0