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 $!;
164 #----- utilities -----
167 print DEBUG "$debug @_\n";
170 sub acquirelock ($$) {
171 my ($lock, $must) = @_;
173 printf DEBUG "$debug locking %s %d\n", $lock, $must;
176 $fh = new IO::File $lock, ">" or die "open $lock: $!";
177 my $ok = flock $fh, $must ? LOCK_EX : (LOCK_EX|LOCK_NB);
179 die "flock $lock: $!" if $must;
180 debug " locking $lock failed";
183 next unless stat_exists $lock;
184 my $want = (stat _)[1];
186 my $got = (stat _)[1];
187 last if $got == $want;
192 sub acquirermtree ($$) {
193 my ($tree, $must) = @_;
194 my $fh = acquirelock("$tree.lock", $must);
202 sub locksometree ($) {
204 acquirelock("$tree.lock", 1);
207 sub lockrealtree () {
208 locksometree($realdestrepo);
212 my $tmpdir = "$dgitrepos/_tmp";
213 return if mkdir $tmpdir;
214 return if $! == EEXIST;
218 sub recorderror ($) {
220 my $w = $ENV{'DGIT_DRS_WORK'}; # we are in stunthook
223 open ERR, ">", "$w/drs-error" or die $!;
224 print ERR $why, "\n" or die $!;
233 recorderror "reject: $why";
234 die "dgit-repos-server: reject: $why\n";
240 local $Data::Dumper::Indent = 0;
241 local $Data::Dumper::Terse = 1;
242 debug "|".Dumper(\@_);
250 die "@_ $? $!" if $r;
254 my ($policyallowbits, @polargs) = @_;
255 # => ($exitstatuspolicybitmap);
256 die if $policyallowbits & ~0x3e;
257 my @cmd = ($policyhook,$distro,$dgitrepos,@polargs);
260 die "system: $!" if $r < 0;
261 die "hook (@cmd) failed ($?)" if $r & ~($policyallowbits << 8);
265 sub mkemptyrepo ($$) {
266 my ($dir,$sharedperm) = @_;
267 runcmd qw(git init --bare --quiet), "--shared=$sharedperm", $dir;
270 sub mkrepo_fromtemplate ($) {
272 my $template = "$dgitrepos/_template";
273 locksometree($template);
274 debug "copy template $template -> $dir";
275 my $r = system qw(cp -a --), $template, $dir;
276 !$r or die "create new repo $dir failed: $r $!";
279 sub movetogarbage () {
280 # $realdestrepo must have been locked
281 my $garbagerepo = "$dgitrepos/${package}_garbage";
282 # We arrange to always keep at least one old tree, for anti-rewind
283 # purposes (and, I guess, recovery from mistakes). This is either
284 # $garbage or $garbage-old.
285 if (stat_exists "$garbagerepo") {
286 rmtree "$garbagerepo-tmp";
287 if (rename "$garbagerepo-old", "$garbagerepo-tmp") {
288 rmtree "$garbagerepo-tmp";
290 die "$garbagerepo $!" unless $!==ENOENT;
292 rename "$garbagerepo", "$garbagerepo-old" or die "$garbagerepo $!";
294 rename $realdestrepo, $garbagerepo
296 or die "$garbagerepo $!";
299 #----- git-receive-pack -----
301 sub fixmissing__git_receive_pack () {
303 $destrepo = "$dgitrepos/_tmp/${package}_prospective";
304 acquirermtree($destrepo, 1);
305 mkrepo_fromtemplate($destrepo);
308 sub makeworkingclone () {
310 $workrepo = "$dgitrepos/_tmp/${package}_incoming$$";
311 acquirermtree($workrepo, 1);
312 my $lfh = lockrealtree();
313 runcmd qw(git clone -l -q --mirror), $destrepo, $workrepo;
315 rmtree "${workrepo}_fresh";
318 sub setupstunthook () {
319 my $prerecv = "$workrepo/hooks/pre-receive";
320 my $fh = new IO::File $prerecv, O_WRONLY|O_CREAT|O_TRUNC, 0777
321 or die "$prerecv: $!";
322 print $fh <<END or die "$prerecv: $!";
325 exec $0 --pre-receive-hook $package
327 close $fh or die "$prerecv: $!";
328 $ENV{'DGIT_DRS_WORK'}= $workrepo;
329 $ENV{'DGIT_DRS_DEST'}= $destrepo;
330 debug " stunt hook set up $prerecv";
333 sub dealwithfreshrepo () {
334 my $freshrepo = "${workrepo}_fresh";
335 return unless stat_exists $freshrepo;
336 $destrepo = $freshrepo;
339 sub maybeinstallprospective () {
340 return if $destrepo eq $realdestrepo;
342 if (open REJ, "<", "$workrepo/drs-error") {
345 REJ->error and die $!;
349 $!==&ENOENT or die $!;
352 debug " show-ref ($destrepo) ...";
354 my $child = open SR, "-|";
355 defined $child or die $!;
357 chdir $destrepo or die $!;
358 exec qw(git show-ref);
361 my %got = qw(tag 0 head 0);
364 debug " show-refs| $_";
365 s/^\S*[1-9a-f]\S* (\S+)$/$1/ or die;
367 m{^refs/tags/} ? 'tag' :
368 m{^refs/dgit/} ? 'head' :
372 $!=0; $?=0; close SR or $?==256 or die "$? $!";
374 debug "installprospective ?";
375 die Dumper(\%got)." -- missing refs in new repo"
376 if grep { !$_ } values %got;
380 if ($destrepo eq "${workrepo}_fresh") {
384 debug "install $destrepo => $realdestrepo";
385 rename $destrepo, $realdestrepo or die $!;
386 remove "$destrepo.lock" or die $!;
389 sub main__git_receive_pack () {
392 runcmd qw(git receive-pack), $workrepo;
394 maybeinstallprospective();
397 #----- stunt post-receive hook -----
399 our ($tagname, $tagval, $suite, $oldcommit, $commit);
400 our ($version, %tagh);
403 debug " updates ...";
407 m/^(\S+) (\S+) (\S+)$/ or die "$_ ?";
408 my ($old, $sha1, $refname) = ($1, $2, $3);
409 if ($refname =~ m{^refs/tags/(?=debian/)}) {
410 reject "pushing multiple tags!" if defined $tagname;
413 reject "tag $tagname already exists -".
414 " not replacing previously-pushed version"
416 } elsif ($refname =~ m{^refs/dgit/}) {
417 reject "pushing multiple heads!" if defined $suite;
422 reject "pushing unexpected ref!";
425 STDIN->error and die $!;
427 reject "push is missing tag ref update" unless defined $tagname;
428 reject "push is missing head ref update" unless defined $suite;
429 debug " updates ok.";
433 debug " parsetag...";
434 open PT, ">dgit-tmp/plaintext" or die $!;
435 open DS, ">dgit-tmp/plaintext.asc" or die $!;
436 open T, "-|", qw(git cat-file tag), $tagval or die $!;
438 $!=0; $_=<T>; defined or die $!;
440 if (m/^(\S+) (.*)/) {
441 push @{ $tagh{$1} }, $2;
448 $!=0; $_=<T>; defined or die $!;
449 m/^($package_re) release (\S+) for \S+ \((\S+)\) \[dgit\]$/ or
450 reject "tag message not in expected format";
452 die unless $1 eq $package;
454 die "$3 != $suite " unless $3 eq $suite;
458 print PT $copyl or die $!;
459 $!=0; $_=<T>; defined or die "missing signature? $!";
461 if (m/^\[dgit ([^"].*)\]$/) { # [dgit "something"] is for future
464 if (s/^distro\=(\S+) //) {
465 die "$1 != $distro" unless $1 eq $distro;
466 } elsif (s/^(--deliberately-$package_re) //) {
467 push @deliberatelies, $1;
468 } elsif (s/^supersede:(\S+)=(\w+) //) {
469 die "supersede $1 twice" if defined $supersedes{$1};
470 $supersedes{$1} = $2;
471 } elsif (s/^[-+.=0-9a-z]\S* //) {
473 die "unknown dgit info in tag ($_)";
478 last if m/^-----BEGIN PGP/;
489 debug " parsetag ok.";
492 sub checksig_keyring ($) {
493 my ($keyringfile) = @_;
494 # returns primary-keyid if signed by a key in this keyring
496 # or dies on other errors
500 debug " checksig keyring $keyringfile...";
502 our @cmd = (qw(gpgv --status-fd=1 --keyring),
504 qw(dgit-tmp/plaintext.asc dgit-tmp/plaintext));
511 next unless s/^\[GNUPG:\] //;
513 debug " checksig| $_";
514 my @l = split / /, $_;
515 if ($l[0] eq 'NO_PUBKEY') {
517 } elsif ($l[0] eq 'VALIDSIG') {
519 $sigtype eq '00' or reject "signature is not of type 00!";
521 die unless defined $ok;
527 debug sprintf " checksig ok=%d", !!$ok;
532 sub dm_txt_check ($$) {
533 my ($keyid, $dmtxtfn) = @_;
534 debug " dm_txt_check $keyid $dmtxtfn";
535 open DT, '<', $dmtxtfn or die "$dmtxtfn $!";
537 m/^fingerprint:\s+$keyid$/oi
539 if (s/^allow:/ /i..0) {
542 or reject "key $keyid missing Allow section in permissions!";
547 or reject "package $package not allowed for key $keyid";
552 debug " dm_txt_check allow| $_";
553 foreach my $p (split /\s+/) {
554 if ($p eq $package) {
556 debug " dm_txt_check ok";
561 DT->error and die $!;
563 reject "key $keyid not in permissions list although in keyring!";
567 foreach my $kas (split /:/, $keyrings) {
568 debug "verifytag $kas...";
569 $kas =~ s/^([^,]+),// or die;
570 my $keyid = checksig_keyring $1;
571 if (defined $keyid) {
572 if ($kas =~ m/^a$/) {
573 debug "verifytag a ok";
575 } elsif ($kas =~ m/^m([^,]+)$/) {
576 dm_txt_check($keyid, $1);
577 debug "verifytag m ok";
584 reject "key not found in keyrings";
588 debug "checksuite ($suitesfile)";
589 open SUITES, "<", $suitesfile or die $!;
595 return if $_ eq $suite;
597 die $! if SUITES->error;
598 reject "unknown suite";
601 sub checktagnoreplay () {
602 # We check that the signed tag mentions the name and value of
603 # (a) in the case of FRESHREPO all tags in the repo;
604 # (b) in the case of just NOFFCHECK all tags referring to
605 # the current head for the suite (there must be at least one).
606 # This prevents a replay attack using an earlier signed tag.
607 return unless $policy & (FRESHREPO|NOFFCHECK);
609 my $garbagerepo = "$dgitrepos/${package}_garbage";
613 foreach my $garb ("$garbagerepo", "$garbagerepo-old") {
614 if (stat_exists $garb) {
615 $ENV{GIT_DIR} = $garb;
619 if (!defined $ENV{GIT_DIR}) {
620 # Nothing to overwrite so the FRESHREPO and NOFFCHECK were
621 # pointless. Oh well.
622 debug "checktagnoreplay - no garbage, ok";
627 if (!($policy & FRESHREPO)) {
628 my $branch = server_branch($suite);
630 `git for-each-ref --format='%(objectname)' '[r]efs/$branch'`;
631 defined or die "$branch $? $!";
632 $? and die "$branch $?";
634 # No such branch - NOFFCHECK was unnecessary. Oh well.
635 debug "checktagnoreplay - not FRESHREPO, new branch, ok";
638 m/^(\w+)\n$/ or die "$branch $_ ?";
640 debug "checktagnoreplay - not FRESHREPO,".
641 " checking for overwriting refs/$branch=$onlyreferring";
646 git_for_each_tag_referring($onlyreferring, sub {
647 my ($objid,$fullrefname,$tagname) = @_;
648 debug "checktagnoreplay - overwriting $fullrefname=$objid";
649 my $supers = $supersedes{$fullrefname};
650 if (!defined $supers) {
651 push @problems, "does not supersede $fullrefname";
652 } elsif ($supers ne $objid) {
654 "supersedes $fullrefname=$supers but previously $fullrefname=$objid";
661 reject "replay attack prevention check failed:".
662 " signed tag for $version: ".
663 join("; ", @problems).
666 debug "checktagnoreply - all ok"
671 my $vals = $tagh{$tag};
672 reject "missing header $tag in signed tag object" unless $vals;
673 reject "multiple headers $tag in signed tag object" unless @$vals == 1;
680 tagh1('type') eq 'commit' or reject "tag refers to wrong kind of object";
681 tagh1('object') eq $commit or reject "tag refers to wrong commit";
682 tagh1('tag') eq $tagname or reject "tag name in tag is wrong";
687 debug "translated version $v";
688 $tagname eq "debian/$v" or die;
692 my @policy_args = ($package,$version,$suite,$tagname,
693 join(",",@deliberatelies));
694 $policy = policyhook(NOFFCHECK|FRESHREPO, 'push', @policy_args);
699 # check that our ref is being fast-forwarded
700 debug "oldcommit $oldcommit";
701 if (!($policy & NOFFCHECK) && $oldcommit =~ m/[^0]/) {
702 $?=0; $!=0; my $mb = `git merge-base $commit $oldcommit`;
704 $mb eq $oldcommit or reject "not fast forward on dgit branch";
707 if ($policy & FRESHREPO) {
708 # This is troublesome. We have been asked by the policy hook
709 # to receive the push into a fresh repo. But of course we
710 # have actually already mostly received the push into the working
711 # repo. (This is unavoidable because the instruction to use a new
712 # repo comes ultimately from the signed tag for the dgit push,
713 # which has to have been received into some repo.)
715 # So what we do is generate a fresh working repo right now and
716 # push the head and tag into it. The presence of this fresh
717 # working repo is detected by the parent, which responds by
718 # making a fresh master repo from the template.
720 $destrepo = "${workrepo}_fresh"; # workrepo lock covers
721 mkrepo_fromtemplate $destrepo;
724 policyhook(0, 'push-confirm', @policy_args);
728 my @cmd = (qw(git send-pack), $destrepo);
729 push @cmd, qw(--force) if $policy & NOFFCHECK;
730 push @cmd, "$commit:refs/dgit/$suite",
731 "$tagval:refs/tags/$tagname";
735 !$r or die "onward push to $destrepo failed: $r $!";
740 chdir $workrepo or die "chdir $workrepo: $!";
741 mkdir "dgit-tmp" or $!==EEXIST or die $!;
747 debug "stunthook done.";
750 #----- git-upload-pack -----
752 sub fixmissing__git_upload_pack () {
753 $destrepo = "$dgitrepos/_empty";
754 my $lfh = locksometree($destrepo);
755 return if stat_exists $destrepo;
756 rmtree "$destrepo.new";
757 mkemptyrepo "$destrepo.new", "0644";
758 rename "$destrepo.new", $destrepo or die $!;
759 unlink "$destrepo.lock" or die $!;
763 sub main__git_upload_pack () {
764 my $lfh = locksometree($destrepo);
765 chdir $destrepo or die "$destrepo: $!";
767 runcmd qw(git upload-pack), ".";
770 #----- arg parsing and main program -----
779 sub parseargsdispatch () {
782 delete $ENV{'GIT_DIR'}; # if not run via ssh, our parent git process
783 delete $ENV{'GIT_PREFIX'}; # sets these and they mess things up
785 if ($ENV{'DGIT_DRS_DEBUG'}) {
787 open DEBUG, ">&STDERR" or die $!;
790 if ($ARGV[0] eq '--pre-receive-hook') {
791 if ($debug) { $debug.="="; }
794 $package = shift @ARGV;
795 defined($distro = $ENV{'DGIT_DRS_DISTRO'}) or die;
796 defined($suitesfile = $ENV{'DGIT_DRS_SUITES'}) or die;
797 defined($workrepo = $ENV{'DGIT_DRS_WORK'}) or die;
798 defined($destrepo = $ENV{'DGIT_DRS_DEST'}) or die;
799 defined($keyrings = $ENV{'DGIT_DRS_KEYRINGS'}) or die $!;
800 defined($policyhook = $ENV{'DGIT_DRS_POLICYHOOK'}) or die $!;
801 open STDOUT, ">&STDERR" or die $!;
806 recorderror "$@" or die;
812 $ENV{'DGIT_DRS_DISTRO'} = $distro = argval();
813 $ENV{'DGIT_DRS_SUITES'} = argval();
814 $ENV{'DGIT_DRS_KEYRINGS'} = argval();
815 $dgitrepos = argval();
816 $ENV{'DGIT_DRS_POLICYHOOK'} = $policyhook = argval();
818 die unless @ARGV==1 && $ARGV[0] eq '--ssh';
820 my $cmd = $ENV{'SSH_ORIGINAL_COMMAND'};
830 or reject "command string not understood";
833 $realdestrepo = "$dgitrepos/$package.git";
837 my $mainfunc = $main::{"main__$funcn"};
839 reject "unknown method" unless $mainfunc;
841 my $lfh = lockrealtree();
843 $policy = policyhook(FRESHREPO,'check-package',$package);
844 if ($policy & FRESHREPO) {
850 if (stat_exists $realdestrepo) {
851 $destrepo = $realdestrepo;
853 debug " fixmissing $funcn";
854 my $fixfunc = $main::{"fixmissing__$funcn"};
858 debug " running main $funcn";
863 while (my $fh = pop @lockfhs) { close $fh; }
868 if (!chdir "$dgitrepos/_tmp") {
869 $!==ENOENT or die $!;
872 foreach my $lf (<*.lock>) {
874 $tree =~ s/\.lock$//;
875 next unless acquirermtree($tree, 0);
876 remove $lf or warn $!;