fix: prevent host shell injection from app.json cron commands

The docker-local scheduler wrote each app.json cron command verbatim into the dokku user's crontab, where cron's `bash -c` interpreted any shell metacharacters in the command on the host as the dokku user rather than inside the container. The crontab line is now `dokku cron:run <app> <cron-id>`, and the command is resolved from app.json and exec'd inside the container at run time. Commands containing shell operators are also rejected when app.json is validated at deploy time.
This commit is contained in:
Jose Diaz-Gonzalez
2026-05-25 02:14:21 -04:00
parent 75c0659dcf
commit ac95225809
5 changed files with 255 additions and 31 deletions

View File

@@ -82,11 +82,14 @@ teardown() {
echo "status: $status"
assert_success
cron_id="$(dokku cron:list $TEST_APP --format json | jq -r '.[0].id')"
run /bin/bash -c "cat /var/spool/cron/crontabs/dokku"
echo "output: $output"
echo "status: $status"
assert_success
assert_output_contains "python3 task.py schedule"
assert_output_contains "dokku cron:run $TEST_APP $cron_id"
assert_output_contains "python3 task.py schedule" 0
}
@test "(cron) create [single-short]" {
@@ -95,11 +98,14 @@ teardown() {
echo "status: $status"
assert_success
cron_id="$(dokku cron:list $TEST_APP --format json | jq -r '.[0].id')"
run /bin/bash -c "cat /var/spool/cron/crontabs/dokku"
echo "output: $output"
echo "status: $status"
assert_success
assert_output_contains "python3 task.py daily"
assert_output_contains "dokku cron:run $TEST_APP $cron_id"
assert_output_contains "python3 task.py daily" 0
}
@test "(cron:report) --global --format json" {
@@ -253,12 +259,17 @@ teardown() {
echo "status: $status"
assert_success
first_id="$(dokku cron:list $TEST_APP --format json | jq -r '.[0].id')"
second_id="$(dokku cron:list $TEST_APP --format json | jq -r '.[1].id')"
run /bin/bash -c "cat /var/spool/cron/crontabs/dokku"
echo "output: $output"
echo "status: $status"
assert_success
assert_output_contains "python3 task.py first"
assert_output_contains "python3 task.py second"
assert_output_contains "dokku cron:run $TEST_APP $first_id"
assert_output_contains "dokku cron:run $TEST_APP $second_id"
assert_output_contains "python3 task.py first" 0
assert_output_contains "python3 task.py second" 0
}
@test "(cron) injected entries" {
@@ -417,38 +428,27 @@ teardown() {
echo "status: $status"
assert_success
first_id="$(dokku cron:list $TEST_APP --format json | jq -r '.[0].id')"
second_id="$(dokku cron:list $TEST_APP --format json | jq -r '.[1].id')"
run /bin/bash -c "cat /var/spool/cron/crontabs/dokku"
echo "output: $output"
echo "status: $status"
assert_success
assert_output_contains "python3 task.py first"
assert_output_contains "python3 task.py second"
assert_output_contains "dokku cron:run $TEST_APP $first_id"
assert_output_contains "dokku cron:run $TEST_APP $second_id"
cron_id="$(dokku cron:list $TEST_APP --format json | jq -r '.[0].id')"
run /bin/bash -c "echo $cron_id"
echo "output: $output"
echo "status: $status"
assert_success
assert_output_exists
first_command="$(dokku cron:list $TEST_APP --format json | jq -r '.[0].command')"
run /bin/bash -c "echo $first_command"
echo "output: $output"
echo "status: $status"
assert_success
assert_output_exists
run /bin/bash -c "dokku cron:report $TEST_APP --cron-maintenance-$cron_id"
run /bin/bash -c "dokku cron:report $TEST_APP --cron-maintenance-$first_id"
echo "output: $output"
echo "status: $status"
assert_failure
run /bin/bash -c "dokku cron:suspend $TEST_APP $cron_id"
run /bin/bash -c "dokku cron:suspend $TEST_APP $first_id"
echo "output: $output"
echo "status: $status"
assert_success
run /bin/bash -c "dokku cron:report $TEST_APP --cron-maintenance-$cron_id"
run /bin/bash -c "dokku cron:report $TEST_APP --cron-maintenance-$first_id"
echo "output: $output"
echo "status: $status"
assert_success
@@ -458,15 +458,15 @@ teardown() {
echo "output: $output"
echo "status: $status"
assert_success
assert_output_contains "python3 task.py first" 0
assert_output_contains "python3 task.py second"
assert_output_contains "dokku cron:run $TEST_APP $first_id" 0
assert_output_contains "dokku cron:run $TEST_APP $second_id"
run /bin/bash -c "dokku cron:resume $TEST_APP $cron_id"
run /bin/bash -c "dokku cron:resume $TEST_APP $first_id"
echo "output: $output"
echo "status: $status"
assert_success
run /bin/bash -c "dokku cron:report $TEST_APP --cron-maintenance-$cron_id"
run /bin/bash -c "dokku cron:report $TEST_APP --cron-maintenance-$first_id"
echo "output: $output"
echo "status: $status"
assert_failure
@@ -475,8 +475,112 @@ teardown() {
echo "output: $output"
echo "status: $status"
assert_success
assert_output_contains "python3 task.py first"
assert_output_contains "python3 task.py second"
assert_output_contains "dokku cron:run $TEST_APP $first_id"
assert_output_contains "dokku cron:run $TEST_APP $second_id"
}
@test "(cron) invalid [command]" {
run deploy_app python dokku@$DOKKU_DOMAIN:$TEST_APP template_cron_file_injection
echo "output: $output"
echo "status: $status"
assert_failure
}
@test "(cron) crontab format [no raw command leakage]" {
run deploy_app python dokku@$DOKKU_DOMAIN:$TEST_APP template_cron_file_valid_single
echo "output: $output"
echo "status: $status"
assert_success
cron_id="$(dokku cron:list $TEST_APP --format json | jq -r '.[0].id')"
run /bin/bash -c "cat /var/spool/cron/crontabs/dokku"
echo "output: $output"
echo "status: $status"
assert_success
assert_output_contains "dokku cron:run $TEST_APP $cron_id"
# User command must never appear verbatim in the crontab - the crontab
# only references the cron ID, and cron:run resolves the command at run
# time and exec's it inside the container.
assert_output_contains "python3 task.py schedule" 0
}
@test "(cron) container labels regression" {
run deploy_app python dokku@$DOKKU_DOMAIN:$TEST_APP template_cron_file_long_running
echo "output: $output"
echo "status: $status"
assert_success
cron_id="$(dokku cron:list $TEST_APP --format json | jq -r '.[0].id')"
run /bin/bash -c "dokku cron:run $TEST_APP $cron_id --detach"
echo "output: $output"
echo "status: $status"
assert_success
run /bin/bash -c "docker ps --filter \"label=com.dokku.cron-id=$cron_id\" -q | xargs docker inspect -f '{{ index .Config.Labels \"com.dokku.cron-id\" }}'"
echo "output: $output"
echo "status: $status"
assert_success
assert_output "$cron_id"
run /bin/bash -c "docker ps --filter \"label=com.dokku.cron-id=$cron_id\" -q | xargs docker inspect -f '{{ index .Config.Labels \"com.dokku.concurrency-policy\" }}'"
echo "output: $output"
echo "status: $status"
assert_success
assert_output "allow"
run /bin/bash -c "docker ps --filter \"label=com.dokku.cron-id=$cron_id\" -q | xargs docker inspect -f '{{ index .Config.Labels \"com.dokku.container-type\" }}'"
echo "output: $output"
echo "status: $status"
assert_success
assert_output "cron"
run /bin/bash -c "docker ps --filter \"label=com.dokku.cron-id=$cron_id\" -q | xargs docker inspect -f '{{ index .Config.Labels \"com.dokku.app-name\" }}'"
echo "output: $output"
echo "status: $status"
assert_success
assert_output "$TEST_APP"
run /bin/bash -c "docker ps --filter \"label=com.dokku.cron-id=$cron_id\" -q | xargs docker inspect -f '{{ index .Config.Labels \"com.dokku.active-deadline-seconds\" }}'"
echo "output: $output"
echo "status: $status"
assert_success
assert_output "86400"
}
template_cron_file_long_running() {
local APP="$1"
local APP_REPO_DIR="$2"
[[ -z "$APP" ]] && local APP="$TEST_APP"
echo "injecting long-running cron app.json -> $APP_REPO_DIR/app.json"
cat <<EOF >"$APP_REPO_DIR/app.json"
{
"cron": [
{
"command": "sleep 30",
"schedule": "0 0 * * *"
}
]
}
EOF
}
template_cron_file_injection() {
local APP="$1"
local APP_REPO_DIR="$2"
[[ -z "$APP" ]] && local APP="$TEST_APP"
echo "injecting injection-attempt cron app.json -> $APP_REPO_DIR/app.json"
cat <<EOF >"$APP_REPO_DIR/app.json"
{
"cron": [
{
"command": "echo CRON_OK; echo hi > /tmp/appjson-injection-test.txt",
"schedule": "* * * * *"
}
]
}
EOF
}
template_cron_file_invalid() {