Merge commit from fork

* enhance: Add a few validation fixes from Sharkey

See the original MR on the GitLab instance:
https://activitypub.software/TransFem-org/Sharkey/-/merge_requests/484

Co-Authored-By: Dakkar <dakkar@thenautilus.net>

* fix: primitive 2: acceptance of cross-origin alternate

Co-Authored-By: Laura Hausmann <laura@hausmann.dev>

* fix: primitive 3: validation of non-final url

* fix: primitive 4: missing same-origin identifier validation of collection-wrapped activities

* fix: primitives 5 & 8: reject activities with non
string identifiers

Co-Authored-By: Laura Hausmann <laura@hausmann.dev>

* fix: primitive 6: reject anonymous objects that were fetched by their id

* fix: primitives 9, 10 & 11: http signature validation
doesn't enforce required headers or specify auth header name

Co-Authored-By: Laura Hausmann <laura@hausmann.dev>

* fix: primitive 14: improper validation of outbox, followers, following & shared inbox collections

* fix: code style for primitive 14

* fix: primitive 15: improper same-origin validation for
note uri and url

Co-Authored-By: Laura Hausmann <laura@hausmann.dev>

* fix: primitive 16: improper same-origin validation for user uri and url

* fix: primitive 17: note same-origin identifier validation can be bypassed by wrapping the id in an array

* fix: code style for primitive 17

* fix: check attribution against actor in notes

While this isn't strictly required to fix the exploits at hand, this
mirrors the fix in `ApQuestionService` for GHSA-5h8r-gq97-xv69, as a
preemptive countermeasure.

* fix: primitive 18: `ap/get` bypasses access checks

One might argue that we could make this one actually preform access
checks against the returned activity object, but I feel like that's a
lot more work than just restricting it to administrators, since, to me
at least, it seems more like a debugging tool than anything else.

* fix: primitive 19 & 20: respect blocks and hide more

Ideally, the user property should also be hidden (as leaving it in leaks
information slightly), but given the schema of the note endpoint, I
don't think that would be possible without introducing some kind of
"ghost" user, who is attributed for posts by users who have you blocked.

* fix: primitives 21, 22, and 23: reuse resolver

This also increases the default `recursionLimit` for `Resolver`, as it
theoretically will go higher that it previously would and could possibly
fail on non-malicious collection activities.

* fix: primitives 25-33: proper local instance checks

* revert: fix: primitive 19 & 20

This reverts commit 465a9fe6591de90f78bd3d084e3c01e65dc3cf3c.

---------

Co-authored-by: Dakkar <dakkar@thenautilus.net>
Co-authored-by: Laura Hausmann <laura@hausmann.dev>
Co-authored-by: syuilo <4439005+syuilo@users.noreply.github.com>

1 files changed, 13 insertions, 1 deletions

diff --git a/packages/backend/src/core/UtilityService.ts b/packages/backend/src/core/UtilityService.ts
index 86082ccdcd..9a2ba72ed3 100644
--- a/packages/backend/src/core/UtilityService.ts
+++ b/packages/backend/src/core/UtilityService.ts
@@ -35,6 +35,11 @@ export class UtilityService {
 	}
 
 	@bindThis
+	public isUriLocal(uri: string): boolean {
+		return this.punyHost(uri) === this.toPuny(this.config.host);
+	}
+
+	@bindThis
 	public isBlockedHost(blockedHosts: string[], host: string | null): boolean {
 		if (host == null) return false;
 		return blockedHosts.some(x => `.${host.toLowerCase()}`.endsWith(`.${x}`));
@@ -96,7 +101,7 @@ export class UtilityService {
 	@bindThis
 	public extractDbHost(uri: string): string {
 		const url = new URL(uri);
-		return this.toPuny(url.hostname);
+		return this.toPuny(url.host);
 	}
 
 	@bindThis
@@ -111,6 +116,13 @@ export class UtilityService {
 	}
 
 	@bindThis
+	public punyHost(url: string): string {
+		const urlObj = new URL(url);
+		const host = `${this.toPuny(urlObj.hostname)}${urlObj.port.length > 0 ? ':' + urlObj.port : ''}`;
+		return host;
+	}
+
+	@bindThis
 	public isFederationAllowedHost(host: string): boolean {
 		if (this.meta.federation === 'none') return false;
 		if (this.meta.federation === 'specified' && !this.meta.federationHosts.some(x => `.${host.toLowerCase()}`.endsWith(`.${x}`))) return false;