* 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.
* Take the SSRF address policy from surfguard instead of keeping our own copy
Four other apps carried this same classification and the five had drifted into
four different ideas of what "internal" means. It now comes from the surfguard
gem, which is their union. resolve and Violation keep their shapes, so the
opengraph callers are unchanged.
Two verdicts change.
SIIT (::ffff:0:0:0/96) is now recognised. It is the third way an IPv4 address
rides inside an IPv6 one and the only one Ruby has no predicate for --
ipv4_mapped?, ipv4_compat?, private?, loopback? and link_local? are all false
for ::ffff:0:a9fe:a9fe, so it fell through to the IPv6 branch unrecognised and
reached the metadata endpoint. Note the extra group: ::ffff:0:0:0/96 is not the
IPv4-mapped ::ffff:0:0/96 the guard already refused, and the two do not overlap.
The RFC 8215 local-use NAT64 block is now refused whole rather than decoded.
Reading its low 32 bits as an embedded IPv4 is only correct for a /96 Pref64;
the block can host any length from /32 to /96 and the position is not
recoverable from the address alone (RFC 6052 2.2), so the decode reads the
wrong octets. It is never globally routed, so refusing it costs nothing. The
well-known /96 is still decoded and re-checked, so DNS64 for public sites on
IPv6-only hosts keeps working.
Resolution moves from Resolv.getaddress to Resolv.getaddresses, so the guard
sees every address a host answers with rather than only the first.
* Distinguish a DNS lookup failure from a private-IP block in the guard
Advance the surfguard pin so resolve_public_ips raises Unresolvable when a
host resolves to nothing and returns an empty list only when it resolves to a
blocked address. The shim lets Unresolvable propagate as a lookup failure --
matching the old Resolv.getaddress behavior -- and reserves Violation for a
resolved-but-blocked address, so a transient DNS miss is no longer reported as
an SSRF attempt.
and add test coverage for (un)supported file types.
The avatar and logo variants move into the models and return nil for content
types that are no longer variable, so the controllers fall back to the initials
avatar and stock logo icon instead of raising `ActiveStorage::InvariableError`.
Matches the fizzy guard: the local-use NAT64 prefix (64:ff9b:1::/48,
RFC 8215) embeds an IPv4 target in its low 32 bits just like the
well-known prefix, so run it through the same embedded-IPv4 recheck.
Local-use NAT64 to a public address now resolves (keeping unfurls
working for self-hosters on such networks) while local-use NAT64 to an
internal address stays blocked.
The local-use NAT64 prefix (64:ff9b:1::/48, RFC 8215) embeds an IPv4
target like the well-known prefix does, but at a deployment-chosen
position we can't extract, so block the whole range outright.
Also block the IPv6 benchmarking range (2001:2::/48, RFC 5180) to match
the IPv4 benchmarking block on 198.18.0.0/15.
The guard blocked the usual private, loopback, and link-local ranges (and
the IPv4-mapped/-compatible IPv6 forms), but let through NAT64, 6to4, and
Teredo addresses, which can point at an internal IPv4, and CGNAT.
Now it pulls the IPv4 out of a NAT64 address and checks that (so NAT64 to a
public site still works), blocks 6to4 and Teredo outright, and adds the
missing IPv4 and IPv6 ranges.
Adds ipv4_mapped? and ipv4_compat? checks to PrivateNetworkGuard.private_ip?
to block SSRF bypass attempts using IPv6 address formats like:
- ::ffff:169.254.169.254 (IPv4-mapped)
- ::169.254.169.254 (IPv4-compatible)
These formats could previously bypass the link_local? check since Ruby
treats them as IPv6 addresses, not IPv4.
Ref: HackerOne #3481701
Jeremy Daer
Mike Dalessio
Donal McBreen
Stanko K.R.