use strict;
-# What we do is this:
+# DGIT-REPOS-DIR contains:
+# git tree (or other object) lock (in acquisition order, outer first)
+#
+# _tmp/PACKAGE_prospective ! } SAME.lock, held during receive-pack
+#
+# _tmp/PACKAGE_incoming$$ ! } SAME.lock, held during receive-pack
+# _tmp/PACKAGE_incoming$$_fresh ! }
+#
+# PACKAGE.git } PACKAGE.git.lock
+# PACKAGE_garbage } (also covers executions of
+# PACKAGE_garbage-old } policy hook script for PACKAGE)
+# PACKAGE_garbage-tmp }
+# policy* } (for policy hook script, covered by
+# } lock only when invoked for a package)
+#
+# leaf locks, held during brief operaton only:
+#
+# _empty } SAME.lock
+# _empty.new }
+#
+# _template } SAME.lock
+#
+# locks marked ! may be held during client data transfer
+
+# What we do on push is this:
# - extract the destination repo name
# - make a hardlink clone of the destination repo
# - provide the destination with a stunt pre-receive hook
# + verify the signature on the signed tag
# and if necessary check that the keyid and package are listed in dm.txt
# + check various correspondences:
-# * the suite is one of those permitted
# * the signed tag must refer to a commit
# * the signed tag commit must be the refs/dgit value
# * the name in the signed tag must correspond to its ref name
# * the tag name must be debian/<version> (massaged as needed)
+# * the suite is one of those permitted
# * the signed tag has a suitable name
-# * the commit is a fast forward
+# * run the "push" policy hook
+# * replay prevention for --deliberately-not-fast-forward
+# * check the commit is a fast forward
+# * handle a request from the policy hook for a fresh repo
# + push the signed tag and new dgit branch to the actual repo
#
# If the destination repo does not already exist, we need to make
# of _template
# - we use the prospective new destination repo instead of the
# actual new destination repo (since the latter doesn't exist)
-# - we set up a post-receive hook as well, which
-# + touches a stamp file
# - after git-receive-pack exits, we
# + check that the prospective repo contains a tag and head
# + rename the prospective destination repo into place
# the corresponding temporary tree, as the lockfile is also
# a stampfile whose presence indicates that there may be
# cleanup to do
+#
+# Policy hook script is invoked like this:
+# POLICY-HOOK-SCRIPT DISTRO DGIT-REPOS-DIR ACTION...
+# ie.
+# POLICY-HOOK-SCRIPT ... check-list [...]
+# POLICY-HOOK-SCRIPT ... check-package PACKAGE [...]
+# POLICY-HOOK-SCRIPT ... push|push-confirm PACKAGE \
+# VERSION SUITE TAGNAME DELIBERATELIES [...]
+#
+# Exit status is a bitmask. Bit weight constants are defined in Dgit.pm.
+# NOFFCHECK (2)
+# suppress dgit-repos-server's fast-forward check ("push" only)
+# FRESHREPO (4)
+# blow away repo right away (ie, as if before push or fetch)
+# ("check-package" and "push" only)
+# any unexpected bits mean failure, and then known set bits are ignored
+# if no unexpected bits set, operation continues (subject to meaning
+# of any expected bits set). So, eg, exit 0 means "continue normally"
+# and would be appropriate for an unknown action.
+#
+# cwd for push and push-confirm is a temporary repo where the
+# to-be-pushed objects have been received; TAGNAME is the
+# version-based tag
+#
+# if push requested FRESHREPO, push-confirm happens in said fresh repo
+#
+# policy hook for a particular package will be invoked only once at
+# a time - (see comments about DGIT-REPOS-DIR, above)
+
use POSIX;
use Fcntl qw(:flock);
our $func;
our $dgitrepos;
our $package;
+our $distro;
our $suitesfile;
our $policyhook;
our $realdestrepo;
our @lockfhs;
our $debug='';
our @deliberatelies;
+our %supersedes;
our $policy;
#----- utilities -----
debug " locking $lock failed";
return undef;
}
- if (!stat $lock) {
- next if $! == ENOENT;
- die "stat $lock: $!";
- }
+ next unless stat_exists $lock;
my $want = (stat _)[1];
stat $fh or die $!;
my $got = (stat _)[1];
return $fh;
}
-sub acquiretree ($$) {
+sub acquirermtree ($$) {
my ($tree, $must) = @_;
my $fh = acquirelock("$tree.lock", $must);
if ($fh) {
return $fh;
}
+sub locksometree ($) {
+ my ($tree) = @_;
+ acquirelock("$tree.lock", 1);
+}
+
+sub lockrealtree () {
+ locksometree($realdestrepo);
+}
+
sub mkrepotmp () {
my $tmpdir = "$dgitrepos/_tmp";
return if mkdir $tmpdir;
sub policyhook {
my ($policyallowbits, @polargs) = @_;
- # => ($exitstatuspolicybitmap, $policylockfh);
+ # => ($exitstatuspolicybitmap);
die if $policyallowbits & ~0x3e;
- my @cmd = ($policyhook,$distro,$repos,@polargs);
- debugcmd @_;
- my $r = system @_;
+ my @cmd = ($policyhook,$distro,$dgitrepos,@polargs);
+ debugcmd @cmd;
+ my $r = system @cmd;
die "system: $!" if $r < 0;
die "hook (@cmd) failed ($?)" if $r & ~($policyallowbits << 8);
return $r >> 8;
sub mkrepo_fromtemplate ($) {
my ($dir) = @_;
my $template = "$dgitrepos/_template";
- debug "copy tempalate $template -> $dir";
+ locksometree($template);
+ debug "copy template $template -> $dir";
my $r = system qw(cp -a --), $template, $dir;
!$r or die "create new repo $dir failed: $r $!";
}
sub movetogarbage () {
- my $garbagerepo = "$dgitrepos/_tmp/${package}_garbage";
- acquiretree($garbagerepo,1);
- rmtree $garbagerepo;
+ # $realdestrepo must have been locked
+ my $garbagerepo = "$dgitrepos/${package}_garbage";
+ # We arrange to always keep at least one old tree, for anti-rewind
+ # purposes (and, I guess, recovery from mistakes). This is either
+ # $garbage or $garbage-old.
+ if (stat_exists "$garbagerepo") {
+ rmtree "$garbagerepo-tmp";
+ if (rename "$garbagerepo-old", "$garbagerepo-tmp") {
+ rmtree "$garbagerepo-tmp";
+ } else {
+ die "$garbagerepo $!" unless $!==ENOENT;
+ }
+ rename "$garbagerepo", "$garbagerepo-old" or die "$garbagerepo $!";
+ }
rename $realdestrepo, $garbagerepo
or $! == ENOENT
- or die "rename repo $realdestrepo to $garbagerepo: $!";
-}
-
-sub onwardpush () {
- my @cmd = (qw(git send-pack), $destrepo);
- push @cmd, qw(--force) if $policy & NOFFCHECK;
- push @cmd, "$commit:refs/dgit/$suite",
- "$tagval:refs/tags/$tagname");
- debugcmd @cmd;
- $!=0;
- my $r = system @cmd;
- !$r or die "onward push to $destrepo failed: $r $!";
+ or die "$garbagerepo $!";
}
#----- git-receive-pack -----
sub fixmissing__git_receive_pack () {
mkrepotmp();
$destrepo = "$dgitrepos/_tmp/${package}_prospective";
- acquiretree($destrepo, 1);
+ acquirermtree($destrepo, 1);
mkrepo_fromtemplate($destrepo);
}
sub makeworkingclone () {
mkrepotmp();
$workrepo = "$dgitrepos/_tmp/${package}_incoming$$";
- acquiretree($workrepo, 1);
+ acquirermtree($workrepo, 1);
+ my $lfh = lockrealtree();
runcmd qw(git clone -l -q --mirror), $destrepo, $workrepo;
+ close $lfh;
rmtree "${workrepo}_fresh";
}
sub dealwithfreshrepo () {
my $freshrepo = "${workrepo}_fresh";
- if (!stat $freshrepo) {
- $!==ENOENT or die "$freshrepo $!";
- return;
- }
+ return unless stat_exists $freshrepo;
$destrepo = $freshrepo;
}
die Dumper(\%got)." -- missing refs in new repo"
if grep { !$_ } values %got;
- movetogarbage; # in case of FRESHREPO
+ lockrealtree();
+
+ if ($destrepo eq "${workrepo}_fresh") {
+ movetogarbage;
+ }
debug "install $destrepo => $realdestrepo";
rename $destrepo, $realdestrepo or die $!;
$version = $2;
die "$3 != $suite " unless $3 eq $suite;
+ my $copyl = $_;
for (;;) {
- print PT or die $!;
+ print PT $copyl or die $!;
$!=0; $_=<T>; defined or die "missing signature? $!";
+ $copyl = $_;
if (m/^\[dgit ([^"].*)\]$/) { # [dgit "something"] is for future
$_ = $1." ";
- for (;;) {
+ while (length) {
if (s/^distro\=(\S+) //) {
die "$1 != $distro" unless $1 eq $distro;
} elsif (s/^(--deliberately-$package_re) //) {
push @deliberatelies, $1;
+ } elsif (s/^supersede:(\S+)=(\w+) //) {
+ die "supersede $1 twice" if defined $supersedes{$1};
+ $supersedes{$1} = $2;
} elsif (s/^[-+.=0-9a-z]\S* //) {
} else {
- die "unknown dgit info in tag";
+ die "unknown dgit info in tag ($_)";
}
}
next;
}
last if m/^-----BEGIN PGP/;
}
+ $_ = $copyl;
for (;;) {
print DS or die $!;
$!=0; $_=<T>;
reject "unknown suite";
}
+sub checktagnoreplay () {
+ # We check that the signed tag mentions the name and value of
+ # (a) in the case of FRESHREPO all tags in the repo;
+ # (b) in the case of just NOFFCHECK all tags referring to
+ # the current head for the suite (there must be at least one).
+ # This prevents a replay attack using an earlier signed tag.
+ return unless $policy & (FRESHREPO|NOFFCHECK);
+
+ my $garbagerepo = "$dgitrepos/${package}_garbage";
+ lockrealtree();
+
+ local $ENV{GIT_DIR};
+ foreach my $garb ("$garbagerepo", "$garbagerepo-old") {
+ if (stat_exists $garb) {
+ $ENV{GIT_DIR} = $garb;
+ last;
+ }
+ }
+ if (!defined $ENV{GIT_DIR}) {
+ # Nothing to overwrite so the FRESHREPO and NOFFCHECK were
+ # pointless. Oh well.
+ debug "checktagnoreplay - no garbage, ok";
+ return;
+ }
+
+ my $onlyreferring;
+ if (!($policy & FRESHREPO)) {
+ my $branch = server_branch($suite);
+ $!=0; $?=0; $_ =
+ `git for-each-ref --format='%(objectname)' '[r]efs/$branch'`;
+ defined or die "$branch $? $!";
+ $? and die "$branch $?";
+ if (!length) {
+ # No such branch - NOFFCHECK was unnecessary. Oh well.
+ debug "checktagnoreplay - not FRESHREPO, new branch, ok";
+ return;
+ }
+ m/^(\w+)\n$/ or die "$branch $_ ?";
+ $onlyreferring = $1;
+ debug "checktagnoreplay - not FRESHREPO,".
+ " checking for overwriting refs/$branch=$onlyreferring";
+ }
+
+ my @problems;
+
+ git_for_each_tag_referring($onlyreferring, sub {
+ my ($objid,$fullrefname,$tagname) = @_;
+ debug "checktagnoreplay - overwriting $fullrefname=$objid";
+ my $supers = $supersedes{$fullrefname};
+ if (!defined $supers) {
+ push @problems, "does not supersede $fullrefname";
+ } elsif ($supers ne $objid) {
+ push @problems,
+ "supersedes $fullrefname=$supers but previously $fullrefname=$objid";
+ } else {
+ # ok;
+ }
+ });
+
+ if (@problems) {
+ reject "replay attack prevention check failed:".
+ " signed tag for $version: ".
+ join("; ", @problems).
+ "\n";
+ }
+ debug "checktagnoreply - all ok"
+}
+
sub tagh1 ($) {
my ($tag) = @_;
my $vals = $tagh{$tag};
debug "translated version $v";
$tagname eq "debian/$v" or die;
- $policy = policyhook(NOFFCHECK|FRESHREPO, 'push',$package,
- $version,$suite,$tagname,
- join(",",@delberatelies));
+ lockrealtree();
+ my @policy_args = ($package,$version,$suite,$tagname,
+ join(",",@deliberatelies));
+ $policy = policyhook(NOFFCHECK|FRESHREPO, 'push', @policy_args);
+
+ checktagnoreplay();
checksuite();
# check that our ref is being fast-forwarded
$destrepo = "${workrepo}_fresh"; # workrepo lock covers
mkrepo_fromtemplate $destrepo;
}
+
+ policyhook(0, 'push-confirm', @policy_args);
+}
+
+sub onwardpush () {
+ my @cmd = (qw(git send-pack), $destrepo);
+ push @cmd, qw(--force) if $policy & NOFFCHECK;
+ push @cmd, "$commit:refs/dgit/$suite",
+ "$tagval:refs/tags/$tagname";
+ debugcmd @cmd;
+ $!=0;
+ my $r = system @cmd;
+ !$r or die "onward push to $destrepo failed: $r $!";
}
sub stunthook () {
sub fixmissing__git_upload_pack () {
$destrepo = "$dgitrepos/_empty";
- my $lfh = acquiretree($destrepo,1);
- return if stat $destrepo;
- die $! unless $!==ENOENT;
+ my $lfh = locksometree($destrepo);
+ return if stat_exists $destrepo;
rmtree "$destrepo.new";
mkemptyrepo "$destrepo.new", "0644";
rename "$destrepo.new", $destrepo or die $!;
}
sub main__git_upload_pack () {
- runcmd qw(git upload-pack), $destrepo;
+ my $lfh = locksometree($destrepo);
+ chdir $destrepo or die "$destrepo: $!";
+ close $lfh;
+ runcmd qw(git upload-pack), ".";
}
#----- arg parsing and main program -----
@ARGV == 1 or die;
$package = shift @ARGV;
defined($distro = $ENV{'DGIT_DRS_DISTRO'}) or die;
+ defined($dgitrepos = $ENV{'DGIT_DRS_REPOS'}) or die;
defined($suitesfile = $ENV{'DGIT_DRS_SUITES'}) or die;
defined($workrepo = $ENV{'DGIT_DRS_WORK'}) or die;
defined($destrepo = $ENV{'DGIT_DRS_DEST'}) or die;
exit 0;
}
- $ENV{'DGIT_DRS_DISTRO'} = argval();
+ $ENV{'DGIT_DRS_DISTRO'} = $distro = argval();
$ENV{'DGIT_DRS_SUITES'} = argval();
$ENV{'DGIT_DRS_KEYRINGS'} = argval();
- $dgitrepos = argval();
+ $ENV{'DGIT_DRS_REPOS'} = $dgitrepos = argval();
$ENV{'DGIT_DRS_POLICYHOOK'} = $policyhook = argval();
die unless @ARGV==1 && $ARGV[0] eq '--ssh';
reject "unknown method" unless $mainfunc;
- my ($policy, $pollock) = policyhook(FRESHREPO,'check-package',$package);
+ my $lfh = lockrealtree();
+
+ $policy = policyhook(FRESHREPO,'check-package',$package);
if ($policy & FRESHREPO) {
movetogarbage;
}
- close $pollock or die $!;
- if (stat $realdestrepo) {
+ close $lfh;
+
+ if (stat_exists $realdestrepo) {
$destrepo = $realdestrepo;
} else {
- $! == ENOENT or die "stat dest repo $destrepo: $!";
debug " fixmissing $funcn";
my $fixfunc = $main::{"fixmissing__$funcn"};
&$fixfunc;
foreach my $lf (<*.lock>) {
my $tree = $lf;
$tree =~ s/\.lock$//;
- next unless acquiretree($tree, 0);
+ next unless acquirermtree($tree, 0);
remove $lf or warn $!;
unlockall();
}
~ianmdlvl / dgit.git / blobdiff