mirror of
https://github.com/basecamp/once-campfire.git
synced 2026-08-31 10:57:42 +09:00
Jeremy Daer
94a48aacb6
* Guard push-subscription endpoints against SSRF Web push delivery POSTed to the endpoint URL a user supplied when registering a subscription, with no scheme, host, or private-network check -- unlike the OpenGraph unfurl path, which already routes through the shared SSRF address policy (surfguard). Any authenticated user could register a subscription whose endpoint pointed at an internal address and have the server fetch it on every chat message: blind SSRF for internal recon and reachability probing, plus a thread-pool DoS on the delivery pool. Validate the endpoint when the subscription is saved: it must be HTTPS, its host must belong to a known browser push service (allowlist), and it must resolve to a public IP. On every delivery, re-resolve the host and pin the connection to that public IP so a later DNS rebind can't redirect the request to an internal address. If no public IP resolves at delivery time -- a rebind, or a subscription that predates this validation -- delivery is skipped rather than falling back to re-resolving the raw host. Adds model, controller, and delivery-pinning tests, plus a DNS stub helper for deterministic resolution in tests. * Route push endpoint guarding through RestrictedHTTP::PrivateNetworkGuard The endpoint SSRF check already delegated its private-network classification to surfguard, but called Surfguard.resolve_public_ips directly rather than through RestrictedHTTP::PrivateNetworkGuard -- the hostname-in, address-out shim #241 established as the app's single guarded-outbound entry point and that Opengraph::Fetch resolves through. Route push resolution through the same guard so once-campfire keeps one place that resolves and classifies outbound addresses. Behavior is unchanged: the guard raises Violation when a permitted host resolves only to blocked addresses (previously an empty list -> nil) and propagates Surfguard::Unresolvable for a host that resolves to nothing; both map to a nil endpoint IP, which fails validation and skips delivery. The allowlist, HTTPS/443 constraints, and per-delivery IP pinning are unchanged. * Address push-SSRF review: defer DNS off enqueue path, disable proxy on pinned path, revalidate on re-registration - Resolve the guarded endpoint IP lazily inside WebPush::Notification#deliver (on the bounded delivery worker) instead of eagerly when the notification is built on the serial enqueue path, so a slow resolver can't stall the push job before any delivery starts. resolved_endpoint_ip only reads the already-loaded endpoint attribute, so it is safe off the AR connection. - Pin the delivery socket with an explicit nil proxy address so http_proxy/ https_proxy can't route the request through a proxy that re-resolves the host and defeats the ipaddr pin. - Revalidate an existing subscription on re-registration so a row predating endpoint validation gets the same 422 as a fresh create instead of being kept alive by touch. - Regression tests: resolution deferred to delivery, pin survives proxy env, legacy invalid row rejected with 422. * Bound the web-push delivery queue (max_queue, not the ignored queue_size) Concurrent::ThreadPoolExecutor takes :max_queue; :queue_size was silently ignored, leaving the delivery backlog unbounded (max_queue: 0). A flood of valid push subscriptions could accumulate queued deliveries without limit -- more acute now that each delivery task also resolves DNS. Using max_queue: 10000 activates the intended cap; overflow raises RejectedExecutionError under the default :abort policy, which deliver_later already rescues (push is best-effort, retried on the next message). * Trim push-SSRF guard comments to match house style Apply the review suggestions on the push-subscription SSRF guard: replace the verbose rationale comments with terse one-liners (or drop them where the code speaks for itself). No behavior change -- the Surfguard-shim routing, per-delivery public-IP pin, and bounded delivery queue are untouched.
62 lines
1.9 KiB
Ruby
62 lines
1.9 KiB
Ruby
require "restricted_http/private_network_guard"
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class Push::Subscription < ApplicationRecord
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PERMITTED_ENDPOINT_HOSTS = %w[
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jmt17.google.com
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fcm.googleapis.com
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updates.push.services.mozilla.com
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web.push.apple.com
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notify.windows.com
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].freeze
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belongs_to :user
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validates :endpoint, presence: true
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validate :validate_endpoint_url
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def notification(**params)
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# Defer DNS lookup to the delivery worker to prevent rebinding
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WebPush::Notification.new(**params, badge: user.memberships.unread.count, endpoint: endpoint, endpoint_ip_resolver: method(:resolved_endpoint_ip), p256dh_key: p256dh_key, auth_key: auth_key)
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end
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# Validate at point of use, not just when saved.
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def resolved_endpoint_ip
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RestrictedHTTP::PrivateNetworkGuard.resolve(endpoint_uri.host) if permitted_endpoint_uri?
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rescue RestrictedHTTP::Violation, Surfguard::Unresolvable
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nil
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end
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private
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# Validate endpoint shape. Belt & suspenders.
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def permitted_endpoint_uri?
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endpoint_uri&.scheme == "https" && endpoint_uri.port == 443 && permitted_endpoint_host?
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end
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def endpoint_uri
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URI.parse(endpoint) if endpoint.present?
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rescue URI::InvalidURIError
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nil
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end
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def validate_endpoint_url
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if endpoint_uri.nil?
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errors.add(:endpoint, "is not a valid URL")
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elsif endpoint_uri.scheme != "https"
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errors.add(:endpoint, "must use HTTPS")
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elsif endpoint_uri.port != 443
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errors.add(:endpoint, "must use the default HTTPS port")
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elsif !permitted_endpoint_host?
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errors.add(:endpoint, "is not a permitted push service")
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elsif resolved_endpoint_ip.nil?
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errors.add(:endpoint, "resolves to a private or invalid IP address")
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end
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end
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def permitted_endpoint_host?
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host = endpoint_uri&.host&.downcase
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host.present? && PERMITTED_ENDPOINT_HOSTS.any? do |permitted|
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host == permitted || host.end_with?(".#{permitted}")
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end
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end
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end
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