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-rw-r--r--modules/tv/git/config.nix272
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
+ };
+}