summaryrefslogtreecommitdiffstats
path: root/krebs/3modules/git.nix
blob: b2d2ec6cce6629c7ff826e6ff04fe761a2be9ea0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
{ config, lib, pkgs, ... }:

# 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)

with import <stockholm/lib>;
let
  cfg = config.krebs.git;

  out = {
    options.krebs.git = api;
    config = with lib; mkIf cfg.enable (mkMerge [
      (mkIf cfg.cgit.enable cgit-imp)
      git-imp
    ]);
  };

  api = {
    enable = mkEnableOption "krebs.git";

    cgit = mkOption {
      type = types.submodule {
        options = {
          enable = mkEnableOption "krebs.git.cgit" // { default = true; };
          fcgiwrap = {
            group = mkOption {
              type = types.group;
              default = {
                name = "fcgiwrap";
              };
            };
            user = mkOption {
              type = types.user;
              default = {
                name = "fcgiwrap";
                home = toString pkgs.empty;
              };
            };
          };
          settings = mkOption {
            apply = flip removeAttrs ["_module"];
            default = {};
            type = subtypes.cgit-settings;
          };
        };
      };
      default = {};
      description = ''
          Cgit is an attempt to create a fast web interface for the git version
          control system, using a built in cache to decrease pressure on the
          git server.
          cgit in this module is being served via fastcgi nginx.This module
          deploys a http://cgit.<hostname> nginx configuration and enables nginx
          if not yet enabled.
          '';
    };
    dataDir = mkOption {
      type = types.str;
      default = "/var/lib/git";
      description = "Directory used to store repositories.";
    };
    etcDir = mkOption {
      type = mkOptionType {
        name = "${types.absolute-pathname.name} starting with `/etc/'";
        check = x: types.absolute-pathname.check x && hasPrefix "/etc/" x;
        merge = mergeOneOption;
      };
      default = "/etc/git";
    };
    repos = mkOption {
      type = types.attrsOf subtypes.repo;
      default = {};
      example = literalExample ''
        {
          testing = {
            name = "testing";
            hooks.post-update = '''
              #! /bin/sh
              set -euf
              echo post-update hook: $* >&2
            ''';
          };
          testing2 = { name = "testing2"; };
        }
      '';
      description = ''
        Repositories.
      '';
    };
    rules = mkOption {
      type = types.listOf subtypes.rule;
      default = [];
      example = literalExample ''
        singleton {
          user = [ config.krebs.users.tv ];
          repo = [ testing ]; # see literal example of repos
          perm = push "refs/*" (with git; [
            non-fast-forward create delete merge
          ]);
        }
      '';
      description = ''
        access and permission rules for git repositories.
      '';
    };

    user = mkOption {
      type = types.user;
      default = {
        name = "git";
        home = toString pkgs.empty;
      };
    };
  };

  # TODO put into krebs/4lib/types.nix?
  subtypes = {
    cgit-settings = types.submodule {
      # A setting's value of `null` means cgit's default should be used.
      options = {
        about-filter = mkOption {
          type = types.nullOr types.package;
          default = null;
        };
        cache-root = mkOption {
          type = types.absolute-pathname;
          default = "/tmp/cgit";
        };
        cache-size = mkOption {
          type = types.uint;
          default = 1000;
        };
        css = mkOption {
          type = types.absolute-pathname;
          default = "/static/cgit.css";
        };
        enable-commit-graph = mkOption {
          type = types.bool;
          default = true;
        };
        enable-index-links = mkOption {
          type = types.bool;
          default = true;
        };
        enable-index-owner = mkOption {
          type = types.bool;
          default = false;
        };
        enable-log-filecount = mkOption {
          type = types.bool;
          default = true;
        };
        enable-log-linecount = mkOption {
          type = types.bool;
          default = true;
        };
        enable-remote-branches = mkOption {
          type = types.bool;
          default = true;
        };
        logo = mkOption {
          type = types.absolute-pathname;
          default = "/static/cgit.png";
        };
        max-stats = mkOption {
          type =
            types.nullOr (types.enum ["week" "month" "quarter" "year"]);
          default = "year";
        };
        readme = mkOption {
          type = types.listOf types.str;
          default = [];
        };
        robots = mkOption {
          type = types.nullOr (types.listOf types.str);
          default = ["nofollow" "noindex"];
        };
        root-desc = mkOption {
          type = types.nullOr types.str;
          default = null;
        };
        root-title = mkOption {
          type = types.nullOr types.str;
          default = null;
        };
        virtual-root = mkOption {
          type = types.nullOr types.absolute-pathname;
          default = "/";
        };
      };
    };
    repo = types.submodule ({ config, ... }: {
      options = {
        admins = mkOption {
          type = types.listOf types.user;
          default = [];
          description = ''
            List of users that should be able to do everything with this repo.

            This option is currently not used by krebs.git but instead can be
            used to create rules.  See e.g. <stockholm/lass/2configs/git.nix> for
            an example.
          '';
        };
        cgit = {
          desc = mkOption {
            type = types.nullOr types.str;
            default = null;
            description = ''
              Repository description.
            '';
          };
          path = mkOption {
            type = types.str;
            default = "${cfg.dataDir}/${config.name}";
            description = ''
              An absolute path to the repository directory. For non-bare
              repositories this is the .git-directory.
            '';
          };
          section = mkOption {
            type = types.nullOr types.str;
            default = null;
            description = ''
              Repository section.
            '';
          };
          url = mkOption {
            type = types.str;
            default = config.name;
            description = ''
              The relative url used to access the repository.
            '';
          };
        };
        collaborators = mkOption {
          type = types.listOf types.user;
          default = [];
          description = ''
            List of users that should be able to fetch from this repo.

            This option is currently not used by krebs.git but instead can be
            used to create rules.  See e.g. <stockholm/tv/2configs/git.nix> for
            an example.
          '';
        };
        name = mkOption {
          type = types.str;
          description = ''
            Repository name.
          '';
        };
        hooks = mkOption {
          type = types.attrsOf types.str;
          default = {};
          description = ''
            Repository-specific hooks.
          '';
        };
        public = mkOption {
          type = types.bool;
          default = false;
          description = ''
            Allow everybody to read the repository via HTTP if cgit enabled.
          '';
          # TODO allow every configured user to fetch the repository via SSH.
        };
      };
    });
    rule = types.submodule ({ config, ... }: {
      options = {
        user = mkOption {
          type = types.listOf types.user;
          description = ''
            List of users this rule should apply to.
            Checked by authorize-command.
          '';
        };
        repo = mkOption {
          type = types.listOf subtypes.repo;
          description = ''
            List of repos this rule should apply to.
            Checked by authorize-command.
          '';
        };
        perm = mkOption {
          type = types.submodule {
            # TODO generate enum argument from krebs/4lib/git.nix
            options = {
              allow-commands = mkOption {
                type = types.listOf (types.enum (with git; [
                  git-receive-pack
                  git-upload-pack
                ]));
                default = [];
                description = ''
                  List of commands the rule's users are allowed to execute.
                  Checked by authorize-command.
                '';
              };
              allow-receive-ref = mkOption {
                type = types.nullOr types.str;
                default = null;
                description = ''
                  Ref that can receive objects.
                  Checked by authorize-push.
                '';
              };
              allow-receive-modes = mkOption {
                type = types.listOf (types.enum (with git; [
                  fast-forward
                  non-fast-forward
                  create
                  delete
                  merge
                ]));
                default = [];
                description = ''
                  List of allowed receive modes.
                  Checked by pre-receive hook.
                '';
              };
            };
          };
          description = ''
            Permissions granted.
          '';
        };
      };
    });
  };

  git-imp = {
    system.activationScripts.git-init = "${init-script}";

    # TODO maybe put all scripts here and then use PATH?
    environment.etc.${removePrefix "/etc/" cfg.etcDir}.source =
      scriptFarm "git-ssh-authorizers" {
        authorize-command = makeAuthorizeScript (map (rule: [
          (map getName (toList rule.user))
          (map getName (toList rule.repo))
          (map getName rule.perm.allow-commands)
        ]) cfg.rules);

        authorize-push = makeAuthorizeScript (map (rule: [
          (map getName (toList rule.user))
          (map getName (toList rule.repo))
          (toList rule.perm.allow-receive-ref)
          (map getName rule.perm.allow-receive-modes)
        ]) (filter (rule: rule.perm.allow-receive-ref != null) cfg.rules));
      };

    users.users.${cfg.user.name} = {
      inherit (cfg.user) home name uid;
      description = "Git repository hosting user";
      extraGroups = [
        # To allow running cgit-clear-cache via hooks.
        cfg.cgit.fcgiwrap.group.name
      ];
      shell = "/bin/sh";
      openssh.authorizedKeys.keys =
        unique
          (sort lessThan
                (map (makeAuthorizedKey git-ssh-command)
                     (filter (user: isString user.pubkey)
                             (concatMap (getAttr "user") cfg.rules))));
    };
  };

  cgit-imp = {
    users = {
      groups.${cfg.cgit.fcgiwrap.group.name} = {
        inherit (cfg.cgit.fcgiwrap.group) name gid;
      };
      users.${cfg.cgit.fcgiwrap.user.name} = {
        inherit (cfg.cgit.fcgiwrap.user) home name uid;
        group = cfg.cgit.fcgiwrap.group.name;
      };
    };

    services.fcgiwrap = {
      enable = true;
      user = cfg.cgit.fcgiwrap.user.name;
      group = cfg.cgit.fcgiwrap.group.name;
      # socketAddress = "/run/fcgiwrap.sock" (default)
      # socketType = "unix" (default)
    };

    environment.etc."cgitrc".text = let
      repo-to-cgitrc = _: repo:
        optionals (isPublicRepo repo) (concatLists [
          [""] # empty line
          [(kv-to-cgitrc "repo.url" repo.cgit.url)]
          (mapAttrsToList kv-to-cgitrc
            (mapAttrs' (k: nameValuePair "repo.${k}")
              (removeAttrs repo.cgit ["url"])))
        ]);

      kv-to-cgitrc = k: v: getAttr (typeOf v) {
        bool = kv-to-cgitrc k (if v then 1 else 0);
        null = []; # This will be removed by `flatten`.
        list = {
          readme = map (x: "readme=${x}") v;
        }.${k} or "${k}=${concatStringsSep ", " v}";
        int = "${k}=${toString v}";
        set =
          if subtypes.cgit-settings.check v
            then "${k}=${v}"
            else error "kv-to-cgitrc: unhandled type: set";
        string = "${k}=${v}";
      };
    in
      concatStringsSep "\n"
        (flatten (
          mapAttrsToList kv-to-cgitrc cfg.cgit.settings
          ++
          mapAttrsToList repo-to-cgitrc cfg.repos
        ));

    environment.systemPackages = [
      (pkgs.cgit-clear-cache.override { inherit (cfg.cgit.settings) cache-root; })
    ];

    system.activationScripts.cgit = ''
      mkdir -m 0770 -p ${cfg.cgit.settings.cache-root}
      chmod 0770 ${cfg.cgit.settings.cache-root}
      chown ${toString cfg.cgit.fcgiwrap.user.name}:${toString cfg.cgit.fcgiwrap.group.name} ${cfg.cgit.settings.cache-root}
    '';

    services.nginx.virtualHosts.cgit = {
      serverAliases = [
        "cgit.${config.networking.hostName}"
        "cgit.${config.networking.hostName}.r"
      ];
      locations."/".extraConfig = ''
        include             ${pkgs.nginx}/conf/fastcgi_params;
        fastcgi_param       SCRIPT_FILENAME ${pkgs.writeDash "cgit-wrapper" ''
          set -efu
          exec 3>&1
          ${pkgs.cgit}/cgit/cgit.cgi "$@" 2>&1 >&3 3>&- \
            | ${pkgs.gnused}/bin/sed \
                  '
                    \|^${pkgs.cgit}/cgit/cgit.cgi: Relink |d
                  '
          exec 3>&-
        ''};
        fastcgi_param       PATH_INFO       $uri;
        fastcgi_param       QUERY_STRING    $args;
        fastcgi_param       HTTP_HOST       $server_name;
        fastcgi_pass        unix:${config.services.fcgiwrap.socketAddress};
      '';
      # Smart HTTP transport.  Regex based on.
      # https://github.com/git/git/blob/v2.27.0/http-backend.c#L708-L721
      locations.''~ "^/[0-9A-Za-z._-]+/(HEAD|info/refs|objects/info/(alternates|http-alternates|packs)|[0-9a-f]{2}/([0-9a-f]{38}|[0-9a-f]{62})|pack/pack-([0-9a-f]{40}|[0-9a-f]{64})\.(pack|idx)|git-upload-pack|git-receive-pack)$"''.extraConfig = ''
        include ${pkgs.nginx}/conf/fastcgi_params;
        fastcgi_param GIT_HTTP_EXPORT_ALL "";
        fastcgi_param GIT_PROJECT_ROOT ${cfg.dataDir};
        fastcgi_param PATH_INFO $fastcgi_script_name;
        fastcgi_param SCRIPT_FILENAME ${pkgs.git}/bin/git-http-backend;
        fastcgi_pass unix:${config.services.fcgiwrap.socketAddress};
      '';
      locations."/static/".extraConfig = ''
        root ${pkgs.cgit}/cgit;
        rewrite ^/static(/.*)$ $1 break;
      '';
    };
  };

  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 "|" (toList 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 use pkgs.write (from nix-writers)
  scriptFarm =
    farm-name: scripts:
    let
      makeScript = script-name: script-string: {
        name = script-name;
        path = pkgs.writeScript "${farm-name}_${script-name}" script-string;
      };
    in
    pkgs.linkFarm farm-name (mapAttrsToList makeScript scripts);


  git-ssh-command = pkgs.writeScript "git-ssh-command" ''
    #! /bin/sh
    set -euf

    PATH=${makeBinPath (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 = pkgs.writeScript "git-init" ''
    #! /bin/sh
    set -euf

    PATH=${makeBinPath (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"
          # TODO fix correctly with stringAfter
          chown -R ${toString config.users.users.git.uid}:nogroup "$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=${makeBinPath (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}''}
    '';
  };

in
out