New approach to replay prevention - WIP

[dgit.git] / infra / dgit-repos-server

diff --git a/infra/dgit-repos-server b/infra/dgit-repos-server
index ae30eeff20d958693d911d6b5f6a931e5decd1b0..ab831364ddb8577284cc5cf3f4019f3d44fc2d27 100755 (executable)
--- a/infra/dgit-repos-server
+++ b/infra/dgit-repos-server
@@ -9,7 +9,7 @@
 #   --suites=SUITES-FILE       default DISTRO-DIR/suites
 #   --policy-hook=POLICY-HOOK  default DISTRO-DIR/policy-hook
 #   --dgit-live=DGIT-LIVE-DIR  default DISTRO-DIR/dgit-live
-# (DISTRO-DIR is not used other than as default)
+# (DISTRO-DIR is not used other than as default and to pass to policy hook)
 # internal usage:
 #  .../dgit-repos-server --pre-receive-hook PACKAGE
 #
@@ -117,7 +117,7 @@ $SIG{__WARN__} = sub { die $_[0]; };
 #    cleanup to do
 #
 # Policy hook script is invoked like this:
-#   POLICY-HOOK-SCRIPT DISTRO DGIT-REPOS-DIR DGIT-LIVE-DIR ACTION...
+#   POLICY-HOOK-SCRIPT DISTRO DGIT-REPOS-DIR DGIT-LIVE-DIR DISTRO-DIR ACTION...
 # ie.
 #   POLICY-HOOK-SCRIPT ... check-list [...]
 #   POLICY-HOOK-SCRIPT ... check-package PACKAGE [...]
@@ -179,6 +179,7 @@ our $distro;
 our $suitesfile;
 our $policyhook;
 our $dgitlive;
+our $distrodir;
 our $destrepo;
 our $workrepo;
 our $keyrings;
@@ -233,12 +234,9 @@ sub lockrealtree () {
     locksometree(realdestrepo);
 }
 
-sub mkrepotmp () {
-    my $tmpdir = "$dgitrepos/_tmp";
-    return if mkdir $tmpdir;
-    return if $! == EEXIST;
-    die $!;
-}
+sub mkrepotmp () { ensuredir "$dgitrepos/_tmp" };
+
+sub removedtagsfile () { "$dgitrepos/_removed-tags/$package"; }
 
 sub recorderror ($) {
     my ($why) = @_;
@@ -270,11 +268,11 @@ sub policyhook {
     my ($policyallowbits, @polargs) = @_;
     # => ($exitstatuspolicybitmap);
     die if $policyallowbits & ~0x3e;
-    my @cmd = ($policyhook,$distro,$dgitrepos,$dgitlive,@polargs);
+    my @cmd = ($policyhook,$distro,$dgitrepos,$dgitlive,$distrodir,@polargs);
     debugcmd '+',@cmd;
     my $r = system @cmd;
     die "system: $!" if $r < 0;
-    die "hook (".(shellquote @cmd).") failed ($?)"
+    die "dgit-repos-server: policy hook failed (or rejected) ($?)\n"
        if $r & ~($policyallowbits << 8);
     printdebug sprintf "hook => %#x\n", $r;
     return $r >> 8;
@@ -301,15 +299,21 @@ sub movetogarbage () {
     # purposes (and, I guess, recovery from mistakes).  This is either
     # $garbage or $garbage-old.
     if (stat_exists "$garbagerepo") {
+       printdebug "movetogarbage: rmtree $garbagerepo-tmp\n";
        rmtree "$garbagerepo-tmp";
        if (rename "$garbagerepo-old", "$garbagerepo-tmp") {
+           printdebug "movetogarbage: $garbagerepo-old -> -tmp, rmtree\n";
            rmtree "$garbagerepo-tmp";
        } else {
            die "$garbagerepo $!" unless $!==ENOENT;
+           printdebug "movetogarbage: $garbagerepo-old -> -tmp\n";
        }
+       printdebug "movetogarbage: $garbagerepo -> -old\n";
        rename "$garbagerepo", "$garbagerepo-old" or die "$garbagerepo $!";
     }
-    rename realdestrepo, $garbagerepo
+    my $real = realdestrepo;
+    printdebug "movetogarbage: $real -> $garbagerepo\n";
+    rename $real, $garbagerepo
        or $! == ENOENT
        or die "$garbagerepo $!";
 }
@@ -492,7 +496,7 @@ sub parsetag () {
            while (length) {
                if (s/^distro\=(\S+) //) {
                    die "$1 != $distro" unless $1 eq $distro;
-               } elsif (s/^(--deliberately-$package_re) //) {
+               } elsif (s/^(--deliberately-$deliberately_re) //) {
                    push @deliberatelies, $1;
                } elsif (s/^supersede:(\S+)=(\w+) //) {
                    die "supersede $1 twice" if defined $supersedes{$1};
@@ -628,10 +632,10 @@ sub checksuite () {
 }
 
 sub checktagnoreplay () {
-    # We check that the signed tag mentions the name and value of
+    # We check that the signed tag mentions the name and tag object id 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).
+    #     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);
 
@@ -673,14 +677,29 @@ sub checktagnoreplay () {
     my @problems;
 
     git_for_each_tag_referring($onlyreferring, sub {
-       my ($objid,$fullrefname,$tagname) = @_;
-       printdebug "checktagnoreplay - overwriting $fullrefname=$objid\n";
+       my ($tagobjid,$refobjid,$fullrefname,$tagname) = @_;
+       printdebug "checktagnoreplay - overwriting".
+           " $fullrefname=$tagobjid->$refobjid\n";
        my $supers = $supersedes{$fullrefname};
        if (!defined $supers) {
-           push @problems, "does not supersede $fullrefname";
-       } elsif ($supers ne $objid) {
+           printdebug "checktagnoreply - fallbacks\n";
+           my $super_fallback = 0;
+           foreach my $didsuper (sort keys %supersedes) {
+               my $didsuper_tagobjid = $supersedes{$didsuper};
+               my $didsuper_refobjid = git_rev_parse $didsuper_tagobjid;
+               printdebug "checktagnoreply - fallback".
+                   " $didsuper=$didsuper_refobjid->$didsuper_tagobjid\n";
+               last if 
+                   $refobjid ne $didsuper_refobjid
+                   and is_fast_fwd($refobjid, $didsuper_refobjid);
+               printdebug "checktagnoreply - fallback $didsuper OK\n";
+               $super_fallback = 1;
+           }
+           push @problems, "does not supersede $fullrefname"
+               unless $super_fallback;
+       } elsif ($supers ne $tagobjid) {
            push @problems,
- "supersedes $fullrefname=$supers but previously $fullrefname=$objid";
+ "supersedes $fullrefname=$supers but previously $fullrefname=$tagobjid";
        } else {
            # ok;
        }
@@ -815,7 +834,8 @@ our %indistrodir = (
     'dgit-live' => \$dgitlive,
     );
 
-our @hookenvs = qw(distro suitesfile policyhook dgitlive keyrings dgitrepos);
+our @hookenvs = qw(distro suitesfile policyhook
+                   dgitlive keyrings dgitrepos distrodir);
 
 # workrepo and destrepo handled ad-hoc
 
@@ -912,9 +932,9 @@ sub parseargsdispatch () {
        exit 0;
     }
 
-    $distro = $ENV{'DGIT_DRS_DISTRO'}     = argval();
-    my $distrodir                         = argval();
-    $keyrings = $ENV{'DGIT_DRS_KEYRINGS'} = argval();
+    $distro    = argval();
+    $distrodir = argval();
+    $keyrings  = argval();
 
     foreach my $dk (keys %indistrodir) {
        ${ $indistrodir{$dk} } = "$distrodir/$dk";