feat: add pam.d restricting su binary, add more modules to be disabled, add grub commandline options for security

grub/grub

@@ -0,0 +1,5 @@
+# These rules are not meant to be copied and pasted as there will
+# likely be other options enabled on your machine.
+# Instead add them to the already existing ones in your /etc/default/grub
+# remove ipv6 disable at the end if needed
+GRUB_CMDLINE_LINUX="slab_nomerge slub_debug=FZ init_on_alloc=1 init_on_free=1 page_alloc.shuffle=1 pti=on vsyscall=none debugfs=off oops=panic module.sig_enforce=1 lockdown=confidentiality mce=0 quiet loglevel=0 ipv6.disable=1"

modprobe/etc/modprobe.d/disable-network-filesystems.conf

@@ -0,0 +1,6 @@
+# Disable only if not used
+install cifs /bin/true
+install nfs /bin/true
+install nfsv3 /bin/true
+install nfsv4 /bin/true
+install gfs2 /bin/true

modprobe/etc/modprobe.d/disable-rare-filesystems.conf

@@ -0,0 +1,7 @@
+install cramfs /bin/false
+install freevxfs /bin/false
+install jffs2 /bin/false
+install hfs /bin/false
+install hfsplus /bin/false
+install squashfs /bin/false
+install udf /bin/false

modprobe/etc/modprobe.d/disable-rare-protocols.conf

@@ -1,4 +1,19 @@
-install dccp /bin/true
+install dccp /bin/false
-install sctp /bin/true
+install sctp /bin/false
-install rds /bin/true
+install rds /bin/false
-install tipc /bin/true
+install tipc /bin/false
+install n-hdlc /bin/false
+install ax25 /bin/false
+install netrom /bin/false
+install x25 /bin/false
+install rose /bin/false
+install decnet /bin/false
+install econet /bin/false
+install af_802154 /bin/false
+install ipx /bin/false
+install appletalk /bin/false
+install psnap /bin/false
+install p8023 /bin/false
+install p8022 /bin/false
+install can /bin/false
+install atm /bin/false

modprobe/etc/modprobe.d/disable-vivid.conf

@@ -0,0 +1 @@
+install vivid /bin/false

pam/etc/pam.d/rocky-linux/su

@@ -0,0 +1,13 @@
+#%PAM-1.0
+auth            required        pam_env.so
+auth            sufficient      pam_rootok.so
+# Uncomment the following line to require a user to be in the "wheel" group.
+auth            required        pam_wheel.so use_uid
+auth            substack        system-auth
+auth            include         postlogin
+account         sufficient      pam_succeed_if.so uid = 0 use_uid quiet
+account         include         system-auth
+password        include         system-auth
+session         include         system-auth
+session         include         postlogin
+session         optional        pam_xauth.so

pam/etc/pam.d/rocky-linux/su-l

@@ -0,0 +1,7 @@
+#%PAM-1.0
+auth            include         su
+account         include         su
+password        include         su
+session         optional        pam_keyinit.so force revoke
+session         include         su
+auth            required        pam_wheel.so use_uid

pam/etc/pam.d/ubuntu/su

@@ -0,0 +1,59 @@
+#
+# The PAM configuration file for the Shadow `su' service
+#
+
+# This allows root to su without passwords (normal operation)
+auth       sufficient pam_rootok.so
+
+# Uncomment this to force users to be a member of group root
+# before they can use `su'. You can also add "group=foo"
+# to the end of this line if you want to use a group other
+# than the default "root" (but this may have side effect of
+# denying "root" user, unless she's a member of "foo" or explicitly
+# permitted earlier by e.g. "sufficient pam_rootok.so").
+# (Replaces the `SU_WHEEL_ONLY' option from login.defs)
+ auth       required   pam_wheel.so
+
+# Uncomment this if you want wheel members to be able to
+# su without a password.
+# auth       sufficient pam_wheel.so trust
+
+# Uncomment this if you want members of a specific group to not
+# be allowed to use su at all.
+# auth       required   pam_wheel.so deny group=nosu
+
+# Uncomment and edit /etc/security/time.conf if you need to set
+# time restrainst on su usage.
+# (Replaces the `PORTTIME_CHECKS_ENAB' option from login.defs
+# as well as /etc/porttime)
+# account    requisite  pam_time.so
+
+# This module parses environment configuration file(s)
+# and also allows you to use an extended config
+# file /etc/security/pam_env.conf.
+#
+# parsing /etc/environment needs "readenv=1"
+session       required   pam_env.so readenv=1
+# locale variables are also kept into /etc/default/locale in etch
+# reading this file *in addition to /etc/environment* does not hurt
+session       required   pam_env.so readenv=1 envfile=/etc/default/locale
+
+# Defines the MAIL environment variable
+# However, userdel also needs MAIL_DIR and MAIL_FILE variables
+# in /etc/login.defs to make sure that removing a user
+# also removes the user's mail spool file.
+# See comments in /etc/login.defs
+#
+# "nopen" stands to avoid reporting new mail when su'ing to another user
+session    optional   pam_mail.so nopen
+
+# Sets up user limits according to /etc/security/limits.conf
+# (Replaces the use of /etc/limits in old login)
+session    required   pam_limits.so
+
+# The standard Unix authentication modules, used with
+# NIS (man nsswitch) as well as normal /etc/passwd and
+# /etc/shadow entries.
+@include common-auth
+@include common-account
+@include common-session

pam/etc/pam.d/ubuntu/su-l

@@ -0,0 +1,7 @@
+#%PAM-1.0
+auth            include         su
+account         include         su
+password        include         su
+session         optional        pam_keyinit.so force revoke
+session         include         su
+auth            required        pam_wheel.so

sysctl/etc/sysctl.conf

@@ -23,18 +23,35 @@ net.ipv4.conf.all.forwarding = 0
 net.ipv4.conf.all.log_martians = 1
 net.ipv4.conf.all.mc_forwarding = 0
 net.ipv4.conf.all.proxy_arp = 0
-net.ipv4.conf.all.rp_filter = 0
+net.ipv4.conf.all.rp_filter = 1
 net.ipv4.conf.all.send_redirects = 0
+net.ipv4.conf.all.secure_redirects=0
+net.ipv4.tcp_rfc1337=1
+net.ipv4.tcp_sack=0
+net.ipv4.tcp_dsack=0
+net.ipv4.tcp_fack=0
 
 net.ipv4.conf.default.accept_redirects = 0
 net.ipv4.conf.default.accept_source_route = 0
 net.ipv4.conf.default.log_martians = 1
+net.ipv4.conf.default.rp_filter=1
+net.ipv4.conf.default.send_redirects=0
+net.ipv4.conf.default.secure_redirects=0
 
 net.ipv4.icmp_echo_ignore_broadcasts = 1
 net.ipv4.icmp_ignore_bogus_error_responses = 1
 net.ipv4.tcp_syncookies = 1
 net.ipv4.tcp_timestamps = 1
 
+dev.tty.ldisc_autoload=0
+vm.unprivileged_userfaultfd=0
+kernel.kexec_load_disabled=1
+kernel.perf_event_paranoid=2
+kernel.yama.ptrace_scope=2
+
+vm.mmap_rnd_bits=32
+vm.mmap_rnd_compat_bits=16
+
 # Uncomment do disable ipv6
 #net.ipv6.conf.all.disable_ipv6=1
 #net.ipv6.conf.default.disable_ipv6=1