diff options
Diffstat (limited to 'modules/tv/git/config.nix')
| -rw-r--r-- | modules/tv/git/config.nix | 272 |
1 files changed, 272 insertions, 0 deletions
diff --git a/modules/tv/git/config.nix b/modules/tv/git/config.nix new file mode 100644 index 000000000..4f44c3839 --- /dev/null +++ b/modules/tv/git/config.nix @@ -0,0 +1,272 @@ +arg@{ cfg, lib, pkgs, ... }: + +let + inherit (builtins) head tail typeOf; + inherit (lib) + attrValues concatStringsSep concatMapStringsSep escapeShellArg filter + getAttr hasAttr hasPrefix lessThan makeSearchPath mapAttrsToList + optional optionalString removePrefix singleton sort unique; + inherit (pkgs) linkFarm writeScript; + + ensureList = x: + if typeOf x == "list" then x else [x]; + + getName = x: x.name; + + isPublicRepo = getAttr "public"; # TODO this is also in ./cgit.nix + + makeAuthorizedKey = git-ssh-command: user@{ name, pubkey }: + # TODO assert name + # TODO assert pubkey + let + options = concatStringsSep "," [ + ''command="exec ${git-ssh-command} ${name}"'' + "no-agent-forwarding" + "no-port-forwarding" + "no-pty" + "no-X11-forwarding" + ]; + in + "${options} ${pubkey}"; + + # [case-pattern] -> shell-script + # Create a shell script that succeeds (exit 0) when all its arguments + # match the case patterns (in the given order). + makeAuthorizeScript = + let + # TODO escape + to-pattern = x: concatStringsSep "|" (ensureList x); + go = i: ps: + if ps == [] + then "exit 0" + else '' + case ''$${toString i} in ${to-pattern (head ps)}) + ${go (i + 1) (tail ps)} + esac''; + in + patterns: '' + #! /bin/sh + set -euf + ${concatStringsSep "\n" (map (go 1) patterns)} + exit -1 + ''; + + reponames = rules: sort lessThan (unique (map (x: x.repo.name) rules)); + + # TODO makeGitHooks that uses runCommand instead of scriptFarm? + scriptFarm = + farm-name: scripts: + let + makeScript = script-name: script-string: { + name = script-name; + path = writeScript "${farm-name}_${script-name}" script-string; + }; + in + linkFarm farm-name (mapAttrsToList makeScript scripts); + + + git-ssh-command = writeScript "git-ssh-command" '' + #! /bin/sh + set -euf + + PATH=${makeSearchPath "bin" (with pkgs; [ + coreutils + git + gnugrep + gnused + systemd + ])} + + abort() { + echo "error: $1" >&2 + systemd-cat -p err -t git echo "error: $1" + exit -1 + } + + GIT_SSH_USER=$1 + + systemd-cat -p info -t git echo \ + "authorizing $GIT_SSH_USER $SSH_CONNECTION $SSH_ORIGINAL_COMMAND" + + # References: The Base Definitions volume of + # POSIX.1‐2013, Section 3.278, Portable Filename Character Set + portable_filename_bre="^[A-Za-z0-9._-]\\+$" + + command=$(echo "$SSH_ORIGINAL_COMMAND" \ + | sed -n 's/^\([^ ]*\) '"'"'\(.*\)'"'"'/\1/p' \ + | grep "$portable_filename_bre" \ + || abort 'cannot read command') + + GIT_SSH_REPO=$(echo "$SSH_ORIGINAL_COMMAND" \ + | sed -n 's/^\([^ ]*\) '"'"'\(.*\)'"'"'/\2/p' \ + | grep "$portable_filename_bre" \ + || abort 'cannot read reponame') + + ${cfg.etcDir}/authorize-command \ + "$GIT_SSH_USER" "$GIT_SSH_REPO" "$command" \ + || abort 'access denied' + + repodir=${escapeShellArg cfg.dataDir}/$GIT_SSH_REPO + + systemd-cat -p info -t git \ + echo "authorized exec $command $repodir" + + export GIT_SSH_USER + export GIT_SSH_REPO + exec "$command" "$repodir" + ''; + + init-script = writeScript "git-init" '' + #! /bin/sh + set -euf + + PATH=${makeSearchPath "bin" (with pkgs; [ + coreutils + findutils + gawk + git + gnugrep + gnused + ])} + + dataDir=${escapeShellArg cfg.dataDir} + mkdir -p "$dataDir" + + # Notice how the presence of hooks symlinks determine whether + # we manage a repositry or not. + + # Make sure that no existing repository has hooks. We can delete + # symlinks because we assume we created them. + find "$dataDir" -mindepth 2 -maxdepth 2 -name hooks -type l -delete + bad_hooks=$(find "$dataDir" -mindepth 2 -maxdepth 2 -name hooks) + if echo "$bad_hooks" | grep -q .; then + printf 'error: unknown hooks:\n%s\n' \ + "$(echo "$bad_hooks" | sed 's/^/ /')" \ + >&2 + exit -1 + fi + + # Initialize repositories. + ${concatMapStringsSep "\n" (repo: + let + hooks = scriptFarm "git-hooks" (makeHooks repo); + in + '' + reponame=${escapeShellArg repo.name} + repodir=$dataDir/$reponame + mode=${toString (if isPublicRepo repo then 0711 else 0700)} + if ! test -d "$repodir"; then + mkdir -m "$mode" "$repodir" + git init --bare --template=/var/empty "$repodir" + chown -R git:nogroup "$repodir" + fi + ln -s ${hooks} "$repodir/hooks" + '' + ) (attrValues cfg.repos)} + + # Warn about repositories that exist but aren't mentioned in the + # current configuration (and thus didn't receive a hooks symlink). + unknown_repos=$(find "$dataDir" -mindepth 1 -maxdepth 1 \ + -type d \! -exec test -e '{}/hooks' \; -print) + if echo "$unknown_repos" | grep -q .; then + printf 'warning: stale repositories:\n%s\n' \ + "$(echo "$unknown_repos" | sed 's/^/ /')" \ + >&2 + fi + ''; + + makeHooks = repo: removeAttrs repo.hooks [ "pre-receive" ] // { + pre-receive = '' + #! /bin/sh + set -euf + + PATH=${makeSearchPath "bin" (with pkgs; [ + coreutils # env + git + systemd + ])} + + accept() { + #systemd-cat -p info -t git echo "authorized $1" + accept_string="''${accept_string+$accept_string + }authorized $1" + } + reject() { + #systemd-cat -p err -t git echo "denied $1" + #echo 'access denied' >&2 + #exit_code=-1 + reject_string="''${reject_string+$reject_string + }access denied: $1" + } + + empty=0000000000000000000000000000000000000000 + + accept_string= + reject_string= + while read oldrev newrev ref; do + + if [ $oldrev = $empty ]; then + receive_mode=create + elif [ $newrev = $empty ]; then + receive_mode=delete + elif [ "$(git merge-base $oldrev $newrev)" = $oldrev ]; then + receive_mode=fast-forward + else + receive_mode=non-fast-forward + fi + + if ${cfg.etcDir}/authorize-push \ + "$GIT_SSH_USER" "$GIT_SSH_REPO" "$ref" "$receive_mode"; then + accept "$receive_mode $ref" + else + reject "$receive_mode $ref" + fi + done + + if [ -n "$reject_string" ]; then + systemd-cat -p err -t git echo "$reject_string" + exit -1 + fi + + systemd-cat -p info -t git echo "$accept_string" + + ${optionalString (hasAttr "post-receive" repo.hooks) '' + # custom post-receive hook + ${repo.hooks.post-receive}''} + ''; + }; + + etc-base = + assert (hasPrefix "/etc/" cfg.etcDir); + removePrefix "/etc/" cfg.etcDir; +in + +{ + system.activationScripts.git-init = "${init-script}"; + + # TODO maybe put all scripts here and then use PATH? + environment.etc."${etc-base}".source = + scriptFarm "git-ssh-authorizers" { + authorize-command = makeAuthorizeScript (map ({ repo, user, perm }: [ + (map getName (ensureList user)) + (map getName (ensureList repo)) + (map getName perm.allow-commands) + ]) cfg.rules); + + authorize-push = makeAuthorizeScript (map ({ repo, user, perm }: [ + (map getName (ensureList user)) + (map getName (ensureList repo)) + (ensureList perm.allow-receive-ref) + (map getName perm.allow-receive-modes) + ]) (filter (x: hasAttr "allow-receive-ref" x.perm) cfg.rules)); + }; + + users.extraUsers = singleton { + description = "Git repository hosting user"; + name = "git"; + shell = "/bin/sh"; + openssh.authorizedKeys.keys = + mapAttrsToList (_: makeAuthorizedKey git-ssh-command) cfg.users; + uid = 112606723; # genid git + }; +} |