Configure Polyinstantiation of /tmp Directories

An XCCDF Rule

Description

To configure polyinstantiated /tmp directories, first create the parent directories which will hold the polyinstantiation child directories. Use the following command:

$ sudo mkdir --mode 000 /tmp/tmp-inst

Then, add the following entry to /etc/security/namespace.conf:

/tmp     /tmp/tmp-inst/            level      root,adm

Rationale

Polyinstantiation of temporary directories is a proactive security measure which reduces chances of attacks that are made possible by /tmp directories being world-writable.

ID: xccdf_org.ssgproject.content_rule_accounts_polyinstantiated_tmp
Severity: Low
References: BP28(R39)
Updated: about 1 year ago


# shellcheck disable=SC2174
mkdir -p --mode 000 /tmp/tmp-inst
chmod 000 /tmp/tmp-inst
chcon --reference=/tmp /tmp/tmp-inst
if ! grep -Eq '^\s*/tmp\s+/tmp/tmp-inst/\s+level\s+root,adm$' /etc/security/namespace.conf ; then
    if grep -Eq '^\s*/tmp\s+' /etc/security/namespace.conf ; then
        sed -i '/^\s*\/tmp/d' /etc/security/namespace.conf
    fi
    echo "/tmp     /tmp/tmp-inst/        level      root,adm" >> /etc/security/namespace.conf
fi

Configure Polyinstantiation of /tmp Directories

Description

Rationale

Remediation - Shell Script