Ensure kernel.kptr_restrict is configured

MoyenneNiveau 1Automatiséelinux

Description

kernel.kptr_restrict sets whether restrictions are placed on exposing kernel addresses via /proc and other interfaces. • kptr_restrict = 0 - The address is hashed before printing. (equivalent to %p.) • kptr_restrict = 1 - kernel pointers printed using the %pK format specifier will be replaced with 0's. • kptr_restrict = 2 - kernel pointers printed using %pK will be replaced with 0's regardless of privileges. More information about the kernel parameter configuration files, their location, and load preference is available in the section overview.

Méthode de vérification

Méthode d'audit: Commande shell

shell

chk() { p=$1; allowed=" $2 "; case $p in net.ipv6.*) [ -d /proc/sys/net/ipv6 ] || return 0;; esac; v=$(sysctl -n "$p" 2>/dev/null) || { echo "$p: not available"; return 1; }; case "$allowed" in *" $v "*) ;; *) echo "$p is $v (running)"; return 1;; esac; sd=$(readlink -e /lib/systemd/systemd-sysctl || readlink -e /usr/lib/systemd/systemd-sysctl); f=$("$sd" --cat-config 2>/dev/null | grep -Po "^\h*${p//./\.}\h*=\h*\K\H+" | tail -n1); [ -n "$f" ] || { echo "$p is not set in any sysctl configuration file"; return 1; }; case "$allowed" in *" $f "*) ;; *) echo "$p is $f in configuration"; return 1;; esac; }; if chk kernel.kptr_restrict '1 2'; then echo compliant; fi

Sortie attendue: compliant

Méthode de correction

Méthode de correction: Recommandation ou correctif d'infrastructure

1. Review all files being used by systemd sysctl and comment out or remove all kernel.kptr_restrict lines that are not kernel.kptr_restrict=1 or kernel.kptr_restrict=2. Example script: #!/usr/bin/env bash { l_option="kernel.kptr_restrict" l_value="(1|2)" l_grep="${l_option//./(\\.|\\/)}" a_files=() l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \ || readlink -e /usr/lib/systemd/systemd-sysctl)" a_files+=("/etc/sysctl.conf") while IFS= read -r l_fname; do l_file="$(readlink -e "${l_fname//# /}")" [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \ <<< "${a_files[*]}" && a_files+=("$l_file") done < <("$l_systemdsysctl" --cat-config | tac | \ grep -Pio '^\h*#\h*\/[^#\n\r\h]…

Propriétés

Systèmes d'exploitation: rocky-9
Étiquettes: cis-convertedkernellinuxsysctl
Référence: CIS Rocky Linux 9 Benchmark v3.0.0 - 1.5.5

Vérifier cet hôte

Exécutez cette commande sur une machine que vous êtes autorisé à auditer. L'analyse est en lecture seule.

shell

tmaegis scan --target linux