Ensure linear history is required

MediumLevel 2Automatedgithub

Description

Linear history is the name for Git history where all commits are listed in chronological order, one after another. Such history exists if a pull request is merged either by rebase merge (re-order the commits history) or squash merge (squashes all commits to one). Enforcing linear history produces a clear record of activity, and as such it offers specific advantages: it is easier to follow, easier to revert a change, and bugs can be found more easily. Checks the default branch: linear history is required. Satisfied by classic branch protection or an active ruleset (rules/branches). Uses the GitHub REST/GraphQL API through gh api (read-only). The repository comes from GH_REPO or the current git checkout (gh's {owner}/{repo} resolution, GH_HOST for GitHub Enterprise Server); the organization comes from GH_ORG (default: the repository owner). Fails when gh is missing or unauthenticated (gh auth login or GH_TOKEN); organization settings and branch protection need an owner/admin token.

How it is checked

Audit method: Shell command

shell

command -v gh >/dev/null 2>&1 || exit 1
gh auth status >/dev/null 2>&1 || exit 1
info=$(gh api 'repos/{owner}/{repo}' --jq '.full_name + " " + .default_branch' 2>/dev/null) || exit 1
R=${info% *}; B=${info#* }
[ -n "$R" ] && [ -n "$B" ] || exit 1
p=$(gh api "repos/$R/branches/$B/protection" --jq '.required_linear_history.enabled == true' 2>/dev/null) || p=false
s=$(gh api "repos/$R/rules/branches/$B" --jq 'any(.[]; .type == "required_linear_history")' 2>/dev/null) || s=false
[ "$p" = true ] || [ "$s" = true ] && echo compliant

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

Settings > Branches (or Rules > Rulesets) for the default branch: enable Require linear history.

Properties

Operating systems: Any
Tags: githubsource-code
Reference: CIS GitHub Benchmark v1.2.0 - 1.1.13 Ensure linear history is required

Check this host

Run this on a machine you are allowed to audit. The scan is read-only.

shell

tmaegis scan --target github --level 2