From 61189ecca9947870c1d6e7186197b3776170224f Mon Sep 17 00:00:00 2001
From: Cole Helbling <cole.helbling@determinate.systems>
Date: Fri, 28 Jan 2022 12:45:12 -0800
Subject: [PATCH] Helper/Nix: constructRunCommandLogPath: verify uuid is valid

This shouldn't be possible normally, but it is possible to:

    $db->resultset('RunCommandLogs')->new({ uuid => "../etc/passwd" });

if you have access to the `$db`.
---
 src/lib/Hydra/Controller/Root.pm |  6 ++++--
 src/lib/Hydra/Helper/Nix.pm      | 16 ++++++++--------
 t/Hydra/Helper/Nix.t             |  6 ++++++
 3 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/src/lib/Hydra/Controller/Root.pm b/src/lib/Hydra/Controller/Root.pm
index 247a6caf..c6843d29 100644
--- a/src/lib/Hydra/Controller/Root.pm
+++ b/src/lib/Hydra/Controller/Root.pm
@@ -537,8 +537,10 @@ sub runcommandlog :Local :Args(1) {
 
     die if defined $tail && $tail !~ /^[0-9]+$/;
 
-    my $runlog = $c->model('DB')->resultset('RunCommandLogs')->find({ uuid => $uuid });
-    my $logFile = constructRunCommandLogPath($runlog) or notFound($c, "RunCommandLog not found.");
+    my $runlog = $c->model('DB')->resultset('RunCommandLogs')->find({ uuid => $uuid })
+        or notFound($c, "The RunCommand log is not available.");
+
+    my $logFile = constructRunCommandLogPath($runlog);
     if (-f $logFile) {
         serveLogFile($c, $logFile, $tail);
         return;
diff --git a/src/lib/Hydra/Helper/Nix.pm b/src/lib/Hydra/Helper/Nix.pm
index 9c804011..6f7852af 100644
--- a/src/lib/Hydra/Helper/Nix.pm
+++ b/src/lib/Hydra/Helper/Nix.pm
@@ -13,6 +13,7 @@ use Nix::Store;
 use Encode;
 use Sys::Hostname::Long;
 use IPC::Run;
+use UUID4::Tiny qw(is_uuid4_string);
 
 our @ISA = qw(Exporter);
 our @EXPORT = qw(
@@ -592,17 +593,16 @@ sub isLocalStore {
 
 sub constructRunCommandLogPath {
     my ($runlog) = @_;
-    my $path = undef;
+    my $uuid = $runlog->uuid;
 
-    eval {
-        my $uuid = $runlog->uuid;
-        my $hydra_path = Hydra::Model::DB::getHydraPath;
-        my $bucket = substr($uuid, 0, 2);
+    if (!is_uuid4_string($uuid)) {
+        die "UUID was invalid."
+    }
 
-        $path = "$hydra_path/runcommand-logs/$bucket/$uuid";
-    };
+    my $hydra_path = Hydra::Model::DB::getHydraPath;
+    my $bucket = substr($uuid, 0, 2);
 
-    return $path;
+    return "$hydra_path/runcommand-logs/$bucket/$uuid";
 }
 
 1;
diff --git a/t/Hydra/Helper/Nix.t b/t/Hydra/Helper/Nix.t
index 8abb60ea..a34cfe02 100644
--- a/t/Hydra/Helper/Nix.t
+++ b/t/Hydra/Helper/Nix.t
@@ -82,6 +82,12 @@ subtest "constructRunCommandLogPath" => sub {
         qr@/runcommand-logs/[0-9a-f]{2}/[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}@,
         "The constructed RunCommandLog path is sufficiently bucketed and UUID-like."
     );
+
+    my $badlog = $db->resultset('RunCommandLogs')->new({ uuid => "../../../etc/passwd" });
+    ok(
+        dies { Hydra::Helper::Nix::constructRunCommandLogPath($badlog) },
+        "Expected invalid UUID to be rejected and not have a path constructed for it.",
+    );
 };
 
 done_testing;