implement sysctl-34 - link protection settings

[rndmh3ro]

see dev-sec/linux-baseline#160

Signed-off-by: rndmh3ro github@gumpri.ch

[partha005]

Hello!

My playbook is stating fs.protected_regular setting is changed, but it doesn't actually reflect in the system:

ok: [localhost] => (item={u'key': u'net.ipv4.conf.all.arp_announce', u'value': 2})
ok: [localhost] => (item={u'key': u'net.ipv4.conf.all.rp_filter', u'value': 1})
changed: [localhost] => (item={u'key': u'fs.protected_regular', u'value': 2}) <<<<<
ok: [localhost] => (item={u'key': u'net.ipv4.conf.default.send_redirects', u'value': 0})
ok: [localhost] => (item={u'key': u'net.ipv4.conf.all.accept_redirects', u'value': 0})

not actually set:
[root@ip-10-0-0-24 roles]# sysctl -n fs.protected_hardlinks fs.protected_regular
1
sysctl: cannot stat /proc/sys/fs/protected_regular: No such file or directory
[root@ip-10-0-0-24 roles]# sysctl -a | egrep -i "fs.protected_hardlinks|fs.protected_regular"
fs.protected_hardlinks = 1
sysctl: reading key "net.ipv6.conf.all.stable_secret"
sysctl: reading key "net.ipv6.conf.default.stable_secret"
sysctl: reading key "net.ipv6.conf.eth0.stable_secret"
sysctl: reading key "net.ipv6.conf.lo.stable_secret"
[root@ip-10-0-0-24 roles]#

Could you please check, or is it possible that the issue is only happening in my system.