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Diffstat (limited to 'modules/tv/git/default.nix')
| -rw-r--r-- | modules/tv/git/default.nix | 347 |
1 files changed, 347 insertions, 0 deletions
diff --git a/modules/tv/git/default.nix b/modules/tv/git/default.nix new file mode 100644 index 000000000..d264125dc --- /dev/null +++ b/modules/tv/git/default.nix @@ -0,0 +1,347 @@ +{ config, lib, pkgs, ... }: + +let + inherit (builtins) + attrNames attrValues concatLists filter hasAttr head lessThan removeAttrs + tail toJSON typeOf; + inherit (lib) + concatMapStringsSep concatStringsSep escapeShellArg hasPrefix + literalExample makeSearchPath mapAttrsToList mkIf mkOption optionalString + removePrefix singleton sort types unique; + inherit (pkgs) linkFarm writeScript writeText; + + + ensureList = x: + if typeOf x == "list" then x else [x]; + + getName = x: x.name; + + makeAuthorizedKey = command-script: user@{ name, pubkey }: + # TODO assert name + # TODO assert pubkey + let + options = concatStringsSep "," [ + ''command="exec ${command-script} ${name}"'' + "no-agent-forwarding" + "no-port-forwarding" + "no-pty" + "no-X11-forwarding" + ]; + in + "${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); + + writeJSON = name: data: writeText name (toJSON data); + + + cfg = config.services.git; +in + +# TODO unify logging of shell scripts to user and journal +# TODO move all scripts to ${etcDir}, so ControlMaster connections +# immediately pick up new authenticators +# TODO when authorized_keys changes, then restart ssh +# (or kill already connected users somehow) + +{ + options.services.git = { + enable = mkOption { + type = types.bool; + default = false; + description = "Enable Git repository hosting."; + }; + dataDir = mkOption { + type = types.str; + default = "/var/lib/git"; + description = "Directory used to store repositories."; + }; + etcDir = mkOption { + type = types.str; + default = "/etc/git-ssh"; + }; + rules = mkOption { + type = types.unspecified; + }; + repos = mkOption { + type = types.attrsOf (types.submodule ({ + options = { + name = mkOption { + type = types.str; + description = '' + Repository name. + ''; + }; + hooks = mkOption { + type = types.attrsOf types.str; + description = '' + Repository-specific hooks. + ''; + }; + }; + })); + + default = {}; + + example = literalExample '' + { + testing = { + name = "testing"; + hooks.post-update = ''' + #! /bin/sh + set -euf + echo post-update hook: $* >&2 + '''; + }; + testing2 = { name = "testing2"; }; + } + ''; + + description = '' + Repositories. + ''; + }; + users = mkOption { + type = types.unspecified; + }; + }; + + config = + let + command-script = writeScript "git-ssh-command" '' + #! /bin/sh + set -euf + + PATH=${makeSearchPath "bin" (with pkgs; [ + coreutils + git + gnugrep + gnused + systemd + ])} + + abort() { + echo "error: $1" >&2 + systemd-cat -p err -t git-ssh echo "error: $1" + exit -1 + } + + GIT_SSH_USER=$1 + + systemd-cat -p info -t git-ssh 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-ssh \ + echo "authorized exec $command $repodir" + + export GIT_SSH_USER + export GIT_SSH_REPO + exec "$command" "$repodir" + ''; + + init-script = writeScript "git-ssh-init" '' + #! /bin/sh + set -euf + + PATH=${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. + ${concatMapStringsSep "\n" (repo: + let + hooks = scriptFarm "git-ssh-hooks" (makeHooks repo); + in + '' + reponame=${escapeShellArg repo.name} + repodir=$dataDir/$reponame + if ! test -d "$repodir"; then + mkdir -m 0700 "$repodir" + git init --bare --template=/var/empty "$repodir" + chown -R git: "$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-ssh echo "authorized $1" + accept_string="''${accept_string+$accept_string + }authorized $1" + } + reject() { + #systemd-cat -p err -t git-ssh 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-ssh echo "$reject_string" + exit -1 + fi + + systemd-cat -p info -t git-ssh echo "$accept_string" + + ${optionalString (hasAttr "post-receive" repo.hooks) '' + # custom post-receive hook + ${repo.hooks.post-receive}''} + ''; + }; + + etc-base = + assert (hasPrefix "/etc/" cfg.etcDir); + removePrefix "/etc/" cfg.etcDir; + in + mkIf cfg.enable { + system.activationScripts.git-ssh-init = "${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 command-script) cfg.users; + uid = 112606723; # genid git + }; + }; +} |