#!/bin/bash
# Kernel parameter hardening - PRD FR-007
# Reference: CIS Benchmark, NIST SP 800-53, PRD security-model.md
set -euo pipefail

echo "Applying kernel hardening parameters..."

# Configure sysctl security parameters
mkdir -p /etc/sysctl.d

cat >/etc/sysctl.d/99-knel-security.conf <<'EOF'
# KNEL-Football Kernel Security Parameters
# Reference: PRD FR-007, CIS Benchmark 3.1-3.4, NIST SP 800-53

# Enable ASLR (Address Space Layout Randomization)
kernel.randomize_va_space = 2

# Restrict ptrace (prevent process inspection by unprivileged users)
kernel.yama.ptrace_scope = 2

# Restrict access to kernel pointer addresses
kernel.kptr_restrict = 2

# Restrict dmesg to privileged users
kernel.dmesg_restrict = 1

# Restrict unprivileged use of BPF
kernel.unprivileged_bpf_disabled = 1

# Restrict kernel profiling
kernel.perf_event_paranoid = 3

# Disable kexec (prevent kernel replacement)
kernel.kexec_load = 0

# Restrict access to kernel logs
dev.tty.ldisc_autoload = 0

# Restrict user namespaces
user.max_user_namespaces = 100

# Disable core dumps for SUID binaries
fs.suid_dumpable = 0

# Protect hardlinks and symlinks
fs.protected_hardlinks = 1
fs.protected_symlinks = 1
fs.protected_fifos = 2
fs.protected_regular = 2

# Network security
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.all.accept_redirects = 0
net.ipv4.conf.default.accept_redirects = 0
net.ipv4.conf.all.secure_redirects = 0
net.ipv4.conf.default.secure_redirects = 0
net.ipv4.conf.all.accept_source_route = 0
net.ipv4.conf.default.accept_source_route = 0
net.ipv4.conf.all.log_martians = 1
net.ipv4.conf.default.log_martians = 1
net.ipv4.icmp_echo_ignore_broadcasts = 1
net.ipv4.icmp_ignore_bogus_error_responses = 1
net.ipv4.tcp_syncookies = 1
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.rp_filter = 1
net.ipv6.conf.all.accept_redirects = 0
net.ipv6.conf.default.accept_redirects = 0
net.ipv6.conf.all.accept_source_route = 0
net.ipv6.conf.default.accept_source_route = 0
EOF

# Apply sysctl settings
sysctl --system 2>/dev/null || true

echo "Kernel hardening completed."