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shankar0123
037dab7b6f
Sprint 1 unified-master-audit closure. Pre-fix the agent built its
on-disk key path via:
keyPath := filepath.Join(a.config.KeyDir, job.CertificateID+".key")
migrations/000001_initial_schema.up.sql declares managed_certificates.id
as TEXT PRIMARY KEY with no shape constraint, so a compromised control
plane (or a poisoned database row) could deliver a job whose
certificate_id is '../../etc/passwd', '/absolute/path', a NUL-byte
payload, or a Windows-separator-laden string — driving arbitrary
file write or read on the agent host.
Fix (two ends; both load-bearing):
Server side:
- New internal/validation/certificate_id.go: ValidateCertificateID
pins the canonical TEXT-PK shape (^[A-Za-z0-9._-]{1,128}$, plus
explicit '.'/'..' rejection).
- CertificateService.Create now invokes ValidateCertificateID after
the existing required-fields check; malformed IDs are refused
before persistence or downstream job creation.
Agent side:
- cmd/agent/keymem.go: validateAgentCertID mirrors the server-side
shape regex. safeAgentKeyPath additionally asserts the joined
path is contained within KeyDir via filepath.Rel — even if a
future refactor bypasses the shape check, a path that escapes
KeyDir fails closed.
- poll.go + deploy.go: both filepath.Join call sites routed
through safeAgentKeyPath; rejection surfaces via reportJobStatus
so the control plane sees the failure.
Regression coverage:
- internal/validation/certificate_id_test.go: production shapes
accepted; explicit rejection table for empty, overlong, posix
traversal, absolute, Windows traversal, Windows separator, NUL
byte, newline/tab injection, drive prefix, space, unicode dots.
- cmd/agent/keymem_test.go: validateAgentCertID acceptance +
rejection tables; safeAgentKeyPath happy path + the 8 audit
vectors plus empty-keyDir refusal.
Closes SEC-002.
68 lines
2.7 KiB
Go
68 lines
2.7 KiB
Go
// Copyright 2026 certctl LLC. All rights reserved.
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// SPDX-License-Identifier: BUSL-1.1
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package validation
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// SEC-002 closure (Sprint 1, 2026-05-16). The agent derives an on-disk
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// key path from `job.CertificateID` via filepath.Join:
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//
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// keyPath := filepath.Join(a.config.KeyDir, job.CertificateID+".key")
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//
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// migrations/000001_initial_schema.up.sql declares managed_certificates.id
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// as TEXT PRIMARY KEY with no shape constraint, so a compromised control
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// plane (or a crafted row in the database) could deliver a job whose
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// certificate_id is "../../etc/passwd", "/absolute/path", a NUL-byte
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// payload, or a Windows-separator-laden string — driving arbitrary
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// file write/read on the agent host.
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//
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// ValidateCertificateID is the server-side shape gate. It pins the
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// canonical TEXT-PK prefix convention used across certctl (lowercase
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// alphanumeric + `_-`, bounded length) and rejects everything else
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// before the row reaches the database or a downstream agent. The
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// agent host owns a symmetric containment check via safeAgentKeyPath
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// in cmd/agent/keymem.go — both ends MUST hold for the load-bearing
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// defense.
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import (
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"fmt"
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"regexp"
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)
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// certificateIDPattern is the canonical shape for managed_certificates.id.
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// Permits ASCII letters, digits, underscore, hyphen, and dot (so existing
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// rows like "mc-cdn-edge-2026.q1" continue to validate). Length capped at
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// 128 — well beyond any human-readable identifier and short enough that
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// a path built from it stays within typical filesystem path limits.
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//
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// Deliberately rejects:
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// - "/" and "\\" (path separators on POSIX + Windows)
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// - ".." (relative-path escape token)
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// - "\x00" (NUL byte truncates the path on many syscalls)
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// - whitespace / control characters
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// - the empty string
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//
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// Existing prefixed IDs in production (`mc-…`, `t-…`, `o-…`, etc.) all
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// satisfy this pattern.
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var certificateIDPattern = regexp.MustCompile(`^[A-Za-z0-9._-]{1,128}$`)
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// ValidateCertificateID returns an error if id is not a well-formed
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// certificate identifier. Callers MUST run this before passing the id
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// to any filesystem-touching code path.
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func ValidateCertificateID(id string) error {
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if id == "" {
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return fmt.Errorf("certificate_id is required")
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}
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if len(id) > 128 {
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return fmt.Errorf("certificate_id length %d exceeds 128", len(id))
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}
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if !certificateIDPattern.MatchString(id) {
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return fmt.Errorf("certificate_id %q contains disallowed characters; allowed: A-Z a-z 0-9 . _ -", id)
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}
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// Defense-in-depth: even within the allowed set, ".." would slip
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// through the regex. Reject it explicitly.
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if id == ".." || id == "." {
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return fmt.Errorf("certificate_id %q is a relative-path token", id)
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}
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return nil
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}
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