selftests/net: convert cmsg tests to make them run in unique namespace

Here is the test result after conversion.

]# ./cmsg_ipv6.sh
OK
]# ./cmsg_so_mark.sh
OK
]# ./cmsg_time.sh
OK
Acked-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

tools/testing/selftests/net/cmsg_ipv6.sh

 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
 
-ksft_skip=4
+source lib.sh
 
-NS=ns
 IP6=2001:db8:1::1/64
 TGT6=2001:db8:1::2
 TMPF=$(mktemp --suffix ".pcap")
@@ -11,13 +10,11 @@ TMPF=$(mktemp --suffix ".pcap")
 cleanup()
 {
     rm -f $TMPF
-    ip netns del $NS
+    cleanup_ns $NS
 }
 
 trap cleanup EXIT
 
-NSEXE="ip netns exec $NS"
-
 tcpdump -h | grep immediate-mode >> /dev/null
 if [ $? -ne 0 ]; then
     echo "SKIP - tcpdump with --immediate-mode option required"
@@ -25,7 +22,8 @@ if [ $? -ne 0 ]; then
 fi
 
 # Namespaces
-ip netns add $NS
+setup_ns NS
+NSEXE="ip netns exec $NS"
 
 $NSEXE sysctl -w net.ipv4.ping_group_range='0 2147483647' > /dev/null
 

tools/testing/selftests/net/cmsg_so_mark.sh

 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
 
-NS=ns
+source lib.sh
+
 IP4=172.16.0.1/24
 TGT4=172.16.0.2
 IP6=2001:db8:1::1/64
@@ -10,13 +11,13 @@ MARK=1000
 
 cleanup()
 {
-    ip netns del $NS
+    cleanup_ns $NS
 }
 
 trap cleanup EXIT
 
 # Namespaces
-ip netns add $NS
+setup_ns NS
 
 ip netns exec $NS sysctl -w net.ipv4.ping_group_range='0 2147483647' > /dev/null
 

tools/testing/selftests/net/cmsg_time.sh

 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
 
-NS=ns
+source lib.sh
+
 IP4=172.16.0.1/24
 TGT4=172.16.0.2
 IP6=2001:db8:1::1/64
@@ -9,13 +10,13 @@ TGT6=2001:db8:1::2
 
 cleanup()
 {
-    ip netns del $NS
+    cleanup_ns $NS
 }
 
 trap cleanup EXIT
 
 # Namespaces
-ip netns add $NS
+setup_ns NS
 
 ip netns exec $NS sysctl -w net.ipv4.ping_group_range='0 2147483647' > /dev/null