5 # .../dgit-repos-server DISTRO SUITES KEYRING-AUTH-SPEC \
6 # DGIT-REPOS-DIR POLICY-HOOK-SCRIPT --ssh
8 # .../dgit-repos-server --pre-receive-hook PACKAGE
10 # Invoked as the ssh restricted command
12 # Works like git-receive-pack
14 # SUITES is the name of a file which lists the permissible suites
15 # one per line (#-comments and blank lines ignored)
17 # KEYRING-AUTH-SPEC is a :-separated list of
18 # KEYRING.GPG,AUTH-SPEC
19 # where AUTH-SPEC is one of
25 # DGIT-REPOS-DIR contains:
26 # git tree (or other object) lock (in acquisition order, outer first)
28 # _tmp/PACKAGE_prospective ! } SAME.lock, held during receive-pack
30 # _tmp/PACKAGE_incoming$$ ! } SAME.lock, held during receive-pack
31 # _tmp/PACKAGE_incoming$$_fresh ! }
33 # PACKAGE.git } PACKAGE.git.lock
34 # PACKAGE_garbage } (also covers executions of
35 # PACKAGE_garbage-old } policy hook script for PACKAGE)
36 # PACKAGE_garbage-tmp }
37 # policy* } (for policy hook script, covered by
38 # } lock only when invoked for a package)
40 # leaf locks, held during brief operaton only:
45 # _template } SAME.lock
47 # locks marked ! may be held during client data transfer
49 # What we do on push is this:
50 # - extract the destination repo name
51 # - make a hardlink clone of the destination repo
52 # - provide the destination with a stunt pre-receive hook
53 # - run actual git-receive-pack with that new destination
54 # as a result of this the stunt pre-receive hook runs; it does this:
55 # + understand what refs we are allegedly updating and
56 # check some correspondences:
57 # * we are updating only refs/tags/debian/* and refs/dgit/*
58 # * and only one of each
59 # * and the tag does not already exist
61 # * recover the suite name from the destination refs/dgit/ ref
62 # + disassemble the signed tag into its various fields and signature
64 # * parsing the first line of the tag message to recover
65 # the package name, version and suite
66 # * checking that the package name corresponds to the dest repo name
67 # * checking that the suite name is as recovered above
68 # + verify the signature on the signed tag
69 # and if necessary check that the keyid and package are listed in dm.txt
70 # + check various correspondences:
71 # * the signed tag must refer to a commit
72 # * the signed tag commit must be the refs/dgit value
73 # * the name in the signed tag must correspond to its ref name
74 # * the tag name must be debian/<version> (massaged as needed)
75 # * the suite is one of those permitted
76 # * the signed tag has a suitable name
77 # * run the "push" policy hook
78 # * replay prevention for --deliberately-not-fast-forward
79 # * check the commit is a fast forward
80 # * handle a request from the policy hook for a fresh repo
81 # + push the signed tag and new dgit branch to the actual repo
83 # If the destination repo does not already exist, we need to make
84 # sure that we create it reasonably atomically, and also that
85 # we don't every have a destination repo containing no refs at all
86 # (because such a thing causes git-fetch-pack to barf). So then we
87 # do as above, except:
88 # - before starting, we take out our own lock for the destination repo
89 # - we create a prospective new destination repo by making a copy
91 # - we use the prospective new destination repo instead of the
92 # actual new destination repo (since the latter doesn't exist)
93 # - after git-receive-pack exits, we
94 # + check that the prospective repo contains a tag and head
95 # + rename the prospective destination repo into place
99 # - Temporary working trees and their locks are cleaned up
100 # opportunistically by a program which tries to take each lock and
101 # if successful deletes both the tree and the lockfile
102 # - Prospective working trees and their locks are cleaned up by
103 # a program which tries to take each lock and if successful
104 # deletes any prospective working tree and the lock (but not
105 # of course any actual tree)
106 # - It is forbidden to _remove_ the lockfile without removing
107 # the corresponding temporary tree, as the lockfile is also
108 # a stampfile whose presence indicates that there may be
111 # Policy hook script is invoked like this:
112 # POLICY-HOOK-SCRIPT DISTRO DGIT-REPOS-DIR ACTION...
114 # POLICY-HOOK-SCRIPT ... check-list [...]
115 # POLICY-HOOK-SCRIPT ... check-package PACKAGE [...]
116 # POLICY-HOOK-SCRIPT ... push|push-confirm PACKAGE \
117 # VERSION SUITE TAGNAME DELIBERATELIES [...]
119 # Exit status is a bitmask. Bit weight constants are defined in Dgit.pm.
121 # suppress dgit-repos-server's fast-forward check ("push" only)
123 # blow away repo right away (ie, as if before push or fetch)
124 # ("check-package" and "push" only)
125 # any unexpected bits mean failure, and then known set bits are ignored
126 # if no unexpected bits set, operation continues (subject to meaning
127 # of any expected bits set). So, eg, exit 0 means "continue normally"
128 # and would be appropriate for an unknown action.
130 # cwd for push and push-confirm is a temporary repo where the
131 # to-be-pushed objects have been received; TAGNAME is the
134 # if push requested FRESHREPO, push-confirm happens in said fresh repo
136 # policy hook for a particular package will be invoked only once at
137 # a time - (see comments about DGIT-REPOS-DIR, above)
141 use Fcntl qw(:flock);
142 use File::Path qw(rmtree);
144 use Debian::Dgit qw(:DEFAULT :policyflags);
146 open DEBUG, ">/dev/null" or die $!;
163 #----- utilities -----
166 print DEBUG "$debug @_\n";
169 sub acquirelock ($$) {
170 my ($lock, $must) = @_;
172 printf DEBUG "$debug locking %s %d\n", $lock, $must;
175 $fh = new IO::File $lock, ">" or die "open $lock: $!";
176 my $ok = flock $fh, $must ? LOCK_EX : (LOCK_EX|LOCK_NB);
178 die "flock $lock: $!" if $must;
179 debug " locking $lock failed";
182 next unless stat_exists $lock;
183 my $want = (stat _)[1];
185 my $got = (stat _)[1];
186 last if $got == $want;
191 sub acquirermtree ($$) {
192 my ($tree, $must) = @_;
193 my $fh = acquirelock("$tree.lock", $must);
201 sub locksometree ($) {
203 acquirelock("$tree.lock", 1);
206 sub lockrealtree () {
207 locksometree($realdestrepo);
211 my $tmpdir = "$dgitrepos/_tmp";
212 return if mkdir $tmpdir;
213 return if $! == EEXIST;
217 sub recorderror ($) {
219 my $w = $ENV{'DGIT_DRS_WORK'}; # we are in stunthook
222 open ERR, ">", "$w/drs-error" or die $!;
223 print ERR $why, "\n" or die $!;
232 recorderror "reject: $why";
233 die "dgit-repos-server: reject: $why\n";
239 local $Data::Dumper::Indent = 0;
240 local $Data::Dumper::Terse = 1;
241 debug "|".Dumper(\@_);
249 die "@_ $? $!" if $r;
253 my ($policyallowbits, @polargs) = @_;
254 # => ($exitstatuspolicybitmap);
255 die if $policyallowbits & ~0x3e;
256 my @cmd = ($policyhook,$distro,$repos,@polargs);
259 die "system: $!" if $r < 0;
260 die "hook (@cmd) failed ($?)" if $r & ~($policyallowbits << 8);
264 sub mkemptyrepo ($$) {
265 my ($dir,$sharedperm) = @_;
266 runcmd qw(git init --bare --quiet), "--shared=$sharedperm", $dir;
269 sub mkrepo_fromtemplate ($) {
271 my $template = "$dgitrepos/_template";
272 locksometree($template);
273 debug "copy template $template -> $dir";
274 my $r = system qw(cp -a --), $template, $dir;
275 !$r or die "create new repo $dir failed: $r $!";
278 sub movetogarbage () {
279 # $realdestrepo must have been locked
280 my $garbagerepo = "$dgitrepos/${package}_garbage";
281 # We arrange to always keep at least one old tree, for anti-rewind
282 # purposes (and, I guess, recovery from mistakes). This is either
283 # $garbage or $garbage-old.
284 if (stat_exists "$garbagerepo") {
285 rmtree "$garbagerepo-tmp";
286 if (rename "$garbagerepo-old", "$garbagerepo-tmp") {
287 rmtree "$garbagerepo-tmp";
289 die "$garbagerepo $!" unless $!==ENOENT;
291 rename "$garbagerepo", "$garbagerepo-old" or die "$garbagerepo $!";
293 rename $realdestrepo, $garbagerepo
295 or die "$garbagerepo $!";
299 my @cmd = (qw(git send-pack), $destrepo);
300 push @cmd, qw(--force) if $policy & NOFFCHECK;
301 push @cmd, "$commit:refs/dgit/$suite",
302 "$tagval:refs/tags/$tagname");
306 !$r or die "onward push to $destrepo failed: $r $!";
309 #----- git-receive-pack -----
311 sub fixmissing__git_receive_pack () {
313 $destrepo = "$dgitrepos/_tmp/${package}_prospective";
314 acquirermtree($destrepo, 1);
315 mkrepo_fromtemplate($destrepo);
318 sub makeworkingclone () {
320 $workrepo = "$dgitrepos/_tmp/${package}_incoming$$";
321 acquirermtree($workrepo, 1);
322 my $lfh = lockrealtree();
323 runcmd qw(git clone -l -q --mirror), $destrepo, $workrepo;
325 rmtree "${workrepo}_fresh";
328 sub setupstunthook () {
329 my $prerecv = "$workrepo/hooks/pre-receive";
330 my $fh = new IO::File $prerecv, O_WRONLY|O_CREAT|O_TRUNC, 0777
331 or die "$prerecv: $!";
332 print $fh <<END or die "$prerecv: $!";
335 exec $0 --pre-receive-hook $package
337 close $fh or die "$prerecv: $!";
338 $ENV{'DGIT_DRS_WORK'}= $workrepo;
339 $ENV{'DGIT_DRS_DEST'}= $destrepo;
340 debug " stunt hook set up $prerecv";
343 sub dealwithfreshrepo () {
344 my $freshrepo = "${workrepo}_fresh";
345 return unless stat_exists $freshrepo;
346 $destrepo = $freshrepo;
349 sub maybeinstallprospective () {
350 return if $destrepo eq $realdestrepo;
352 if (open REJ, "<", "$workrepo/drs-error") {
355 REJ->error and die $!;
359 $!==&ENOENT or die $!;
362 debug " show-ref ($destrepo) ...";
364 my $child = open SR, "-|";
365 defined $child or die $!;
367 chdir $destrepo or die $!;
368 exec qw(git show-ref);
371 my %got = qw(tag 0 head 0);
374 debug " show-refs| $_";
375 s/^\S*[1-9a-f]\S* (\S+)$/$1/ or die;
377 m{^refs/tags/} ? 'tag' :
378 m{^refs/dgit/} ? 'head' :
382 $!=0; $?=0; close SR or $?==256 or die "$? $!";
384 debug "installprospective ?";
385 die Dumper(\%got)." -- missing refs in new repo"
386 if grep { !$_ } values %got;
390 if ($destrepo eq "${workrepo}_fresh") {
394 debug "install $destrepo => $realdestrepo";
395 rename $destrepo, $realdestrepo or die $!;
396 remove "$destrepo.lock" or die $!;
399 sub main__git_receive_pack () {
402 runcmd qw(git receive-pack), $workrepo;
404 maybeinstallprospective();
407 #----- stunt post-receive hook -----
409 our ($tagname, $tagval, $suite, $oldcommit, $commit);
410 our ($version, %tagh);
413 debug " updates ...";
417 m/^(\S+) (\S+) (\S+)$/ or die "$_ ?";
418 my ($old, $sha1, $refname) = ($1, $2, $3);
419 if ($refname =~ m{^refs/tags/(?=debian/)}) {
420 reject "pushing multiple tags!" if defined $tagname;
423 reject "tag $tagname already exists -".
424 " not replacing previously-pushed version"
426 } elsif ($refname =~ m{^refs/dgit/}) {
427 reject "pushing multiple heads!" if defined $suite;
432 reject "pushing unexpected ref!";
435 STDIN->error and die $!;
437 reject "push is missing tag ref update" unless defined $tagname;
438 reject "push is missing head ref update" unless defined $suite;
439 debug " updates ok.";
443 debug " parsetag...";
444 open PT, ">dgit-tmp/plaintext" or die $!;
445 open DS, ">dgit-tmp/plaintext.asc" or die $!;
446 open T, "-|", qw(git cat-file tag), $tagval or die $!;
448 $!=0; $_=<T>; defined or die $!;
450 if (m/^(\S+) (.*)/) {
451 push @{ $tagh{$1} }, $2;
458 $!=0; $_=<T>; defined or die $!;
459 m/^($package_re) release (\S+) for \S+ \((\S+)\) \[dgit\]$/ or
460 reject "tag message not in expected format";
462 die unless $1 eq $package;
464 die "$3 != $suite " unless $3 eq $suite;
468 $!=0; $_=<T>; defined or die "missing signature? $!";
469 if (m/^\[dgit ([^"].*)\]$/) { # [dgit "something"] is for future
472 if (s/^distro\=(\S+) //) {
473 die "$1 != $distro" unless $1 eq $distro;
474 } elsif (s/^(--deliberately-$package_re) //) {
475 push @deliberatelies, $1;
476 } elsif (s/^supersede:(\S+)=(\w+) //) {
477 die "supersede $1 twice" if defined $supersedes{$1};
478 $supersedes{$1} = $2;
479 } elsif (s/^[-+.=0-9a-z]\S* //) {
481 die "unknown dgit info in tag";
486 last if m/^-----BEGIN PGP/;
496 debug " parsetag ok.";
499 sub checksig_keyring ($) {
500 my ($keyringfile) = @_;
501 # returns primary-keyid if signed by a key in this keyring
503 # or dies on other errors
507 debug " checksig keyring $keyringfile...";
509 our @cmd = (qw(gpgv --status-fd=1 --keyring),
511 qw(dgit-tmp/plaintext.asc dgit-tmp/plaintext));
518 next unless s/^\[GNUPG:\] //;
520 debug " checksig| $_";
521 my @l = split / /, $_;
522 if ($l[0] eq 'NO_PUBKEY') {
524 } elsif ($l[0] eq 'VALIDSIG') {
526 $sigtype eq '00' or reject "signature is not of type 00!";
528 die unless defined $ok;
534 debug sprintf " checksig ok=%d", !!$ok;
539 sub dm_txt_check ($$) {
540 my ($keyid, $dmtxtfn) = @_;
541 debug " dm_txt_check $keyid $dmtxtfn";
542 open DT, '<', $dmtxtfn or die "$dmtxtfn $!";
544 m/^fingerprint:\s+$keyid$/oi
546 if (s/^allow:/ /i..0) {
549 or reject "key $keyid missing Allow section in permissions!";
554 or reject "package $package not allowed for key $keyid";
559 debug " dm_txt_check allow| $_";
560 foreach my $p (split /\s+/) {
561 if ($p eq $package) {
563 debug " dm_txt_check ok";
568 DT->error and die $!;
570 reject "key $keyid not in permissions list although in keyring!";
574 foreach my $kas (split /:/, $keyrings) {
575 debug "verifytag $kas...";
576 $kas =~ s/^([^,]+),// or die;
577 my $keyid = checksig_keyring $1;
578 if (defined $keyid) {
579 if ($kas =~ m/^a$/) {
580 debug "verifytag a ok";
582 } elsif ($kas =~ m/^m([^,]+)$/) {
583 dm_txt_check($keyid, $1);
584 debug "verifytag m ok";
591 reject "key not found in keyrings";
595 debug "checksuite ($suitesfile)";
596 open SUITES, "<", $suitesfile or die $!;
602 return if $_ eq $suite;
604 die $! if SUITES->error;
605 reject "unknown suite";
608 sub checktagnoreplay () {
609 # We check that the signed tag mentions the name and value of
610 # (a) in the case of FRESHREPO all tags in the repo;
611 # (b) in the case of just NOFFCHECK all tags referring to
612 # the current head for the suite (there must be at least one).
613 # This prevents a replay attack using an earlier signed tag.
614 return unless $policy & (FRESHREPO|NOFFCHECK);
616 my $garbagerepo = "$dgitrepos/${package}_garbage";
620 foreach my $garb ("$garbagerepo", "$garbagerepo-old") {
621 if (stat_exists $garb) {
622 $ENV{GIT_DIR} = $garb;
626 if (!defined $ENV{GIT_DIR}) {
627 # Nothing to overwrite so the FRESHREPO and NOFFCHECK were
628 # pointless. Oh well.
629 debug "checktagnoreplay - no garbage, ok";
634 if (!($policy & FRESHREPO)) {
635 my $branch = server_branch($suite);
637 `git for-each-ref --format='%(objectname)' '[r]efs/$branch'`;
638 defined or die "$branch $? $!";
639 $? and die "$branch $?";
641 # No such branch - NOFFCHECK was unnecessary. Oh well.
642 debug "checktagnoreplay - not FRESHREPO, new branch, ok";
645 m/^(\w+)\n$/ or die "$branch $_ ?";
647 debug "checktagnoreplay - not FRESHREPO,".
648 " checking for overwriting refs/$branch=$onlyreferring";
653 git_for_each_tag_referring($objreferring, sub {
654 my ($objid,$fullrefname,$tagname) = @_;
655 debug "checktagnoreplay - overwriting $fullrefname=$objid";
656 my $supers = $supersedes{$fullrefname};
657 if (!defined $supers) {
658 push @problems, "does not supersede $fullrefname";
659 } elsif ($supers ne $objid) {
661 "supersedes $fullrefname=$supers but previously $fullrefname=$objid";
668 reject "replay attack prevention check failed:".
669 " signed tag for $version: ".
670 join("; ", @problems).
673 debug "checktagnoreply - all ok"
678 my $vals = $tagh{$tag};
679 reject "missing header $tag in signed tag object" unless $vals;
680 reject "multiple headers $tag in signed tag object" unless @$vals == 1;
687 tagh1('type') eq 'commit' or reject "tag refers to wrong kind of object";
688 tagh1('object') eq $commit or reject "tag refers to wrong commit";
689 tagh1('tag') eq $tagname or reject "tag name in tag is wrong";
694 debug "translated version $v";
695 $tagname eq "debian/$v" or die;
699 my @policy_args = ($package,$version,$suite,$tagname,
700 join(",",@delberatelies));
701 $policy = policyhook(NOFFCHECK|FRESHREPO, 'push', @policy_args);
706 # check that our ref is being fast-forwarded
707 debug "oldcommit $oldcommit";
708 if (!($policy & NOFFCHECK) && $oldcommit =~ m/[^0]/) {
709 $?=0; $!=0; my $mb = `git merge-base $commit $oldcommit`;
711 $mb eq $oldcommit or reject "not fast forward on dgit branch";
714 if ($policy & FRESHREPO) {
715 # This is troublesome. We have been asked by the policy hook
716 # to receive the push into a fresh repo. But of course we
717 # have actually already mostly received the push into the working
718 # repo. (This is unavoidable because the instruction to use a new
719 # repo comes ultimately from the signed tag for the dgit push,
720 # which has to have been received into some repo.)
722 # So what we do is generate a fresh working repo right now and
723 # push the head and tag into it. The presence of this fresh
724 # working repo is detected by the parent, which responds by
725 # making a fresh master repo from the template.
727 $destrepo = "${workrepo}_fresh"; # workrepo lock covers
728 mkrepo_fromtemplate $destrepo;
731 policyhook(0, 'push-confirm', @policy_args);
736 chdir $workrepo or die "chdir $workrepo: $!";
737 mkdir "dgit-tmp" or $!==EEXIST or die $!;
743 debug "stunthook done.";
746 #----- git-upload-pack -----
748 sub fixmissing__git_upload_pack () {
749 $destrepo = "$dgitrepos/_empty";
750 my $lfh = locksometree($destrepo);
751 return if stat_exists $destrepo;
752 rmtree "$destrepo.new";
753 mkemptyrepo "$destrepo.new", "0644";
754 rename "$destrepo.new", $destrepo or die $!;
755 unlink "$destrepo.lock" or die $!;
759 sub main__git_upload_pack () {
760 my $lfh = locksometree($destrepo);
761 chdir $destrepo or die "$destrepo: $!";
763 runcmd qw(git upload-pack), ".";
766 #----- arg parsing and main program -----
775 sub parseargsdispatch () {
778 delete $ENV{'GIT_DIR'}; # if not run via ssh, our parent git process
779 delete $ENV{'GIT_PREFIX'}; # sets these and they mess things up
781 if ($ENV{'DGIT_DRS_DEBUG'}) {
783 open DEBUG, ">&STDERR" or die $!;
786 if ($ARGV[0] eq '--pre-receive-hook') {
787 if ($debug) { $debug.="="; }
790 $package = shift @ARGV;
791 defined($distro = $ENV{'DGIT_DRS_DISTRO'}) or die;
792 defined($suitesfile = $ENV{'DGIT_DRS_SUITES'}) or die;
793 defined($workrepo = $ENV{'DGIT_DRS_WORK'}) or die;
794 defined($destrepo = $ENV{'DGIT_DRS_DEST'}) or die;
795 defined($keyrings = $ENV{'DGIT_DRS_KEYRINGS'}) or die $!;
796 defined($policyhook = $ENV{'DGIT_DRS_POLICYHOOK'}) or die $!;
797 open STDOUT, ">&STDERR" or die $!;
802 recorderror "$@" or die;
808 $ENV{'DGIT_DRS_DISTRO'} = argval();
809 $ENV{'DGIT_DRS_SUITES'} = argval();
810 $ENV{'DGIT_DRS_KEYRINGS'} = argval();
811 $dgitrepos = argval();
812 $ENV{'DGIT_DRS_POLICYHOOK'} = $policyhook = argval();
814 die unless @ARGV==1 && $ARGV[0] eq '--ssh';
816 my $cmd = $ENV{'SSH_ORIGINAL_COMMAND'};
826 or reject "command string not understood";
829 $realdestrepo = "$dgitrepos/$package.git";
833 my $mainfunc = $main::{"main__$funcn"};
835 reject "unknown method" unless $mainfunc;
837 my $lfh = lockrealtree();
839 $policy = policyhook(FRESHREPO,'check-package',$package);
840 if ($policy & FRESHREPO) {
846 if (stat_exists $realdestrepo) {
847 $destrepo = $realdestrepo;
849 debug " fixmissing $funcn";
850 my $fixfunc = $main::{"fixmissing__$funcn"};
854 debug " running main $funcn";
859 while (my $fh = pop @lockfhs) { close $fh; }
864 if (!chdir "$dgitrepos/_tmp") {
865 $!==ENOENT or die $!;
868 foreach my $lf (<*.lock>) {
870 $tree =~ s/\.lock$//;
871 next unless acquirermtree($tree, 0);
872 remove $lf or warn $!;