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content / browser / renderer_host / private_network_access_util.cc [blame]
// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "content/browser/renderer_host/private_network_access_util.h"
#include "base/command_line.h"
#include "base/feature_list.h"
#include "build/chromeos_buildflags.h"
#include "content/browser/renderer_host/policy_container_host.h"
#include "content/common/features.h"
#include "content/public/browser/content_browser_client.h"
#include "content/public/common/content_features.h"
#include "content/public/common/content_switches.h"
#include "content/public/common/url_constants.h"
#include "services/network/public/cpp/cross_origin_embedder_policy.h"
#include "services/network/public/cpp/ip_address_space_util.h"
#include "services/network/public/mojom/client_security_state.mojom.h"
#include "services/network/public/mojom/ip_address_space.mojom.h"
#include "services/network/public/mojom/url_response_head.mojom.h"
namespace content {
namespace {
using Policy = network::mojom::PrivateNetworkRequestPolicy;
using AddressSpace = network::mojom::IPAddressSpace;
using RequestContext = PrivateNetworkRequestContext;
// Represents the state of feature flags for a given `RequestContext`.
enum class FeatureState {
kDisabled,
kWarningOnly,
kEnabled,
};
FeatureState FeatureStateForContext(RequestContext request_context) {
switch (request_context) {
case RequestContext::kSubresource:
return FeatureState::kEnabled;
case RequestContext::kWorker:
if (!base::FeatureList::IsEnabled(
features::kPrivateNetworkAccessForWorkers)) {
return FeatureState::kDisabled;
}
if (base::FeatureList::IsEnabled(
features::kPrivateNetworkAccessForWorkersWarningOnly)) {
return FeatureState::kWarningOnly;
}
return FeatureState::kEnabled;
case RequestContext::kNavigation:
if (!base::FeatureList::IsEnabled(
features::kPrivateNetworkAccessForNavigations)) {
return FeatureState::kDisabled;
}
if (base::FeatureList::IsEnabled(
features::kPrivateNetworkAccessForNavigationsWarningOnly)) {
return FeatureState::kWarningOnly;
}
return FeatureState::kEnabled;
}
}
} // namespace
Policy DerivePrivateNetworkRequestPolicy(
const PolicyContainerPolicies& policies,
RequestContext private_network_request_context) {
return DerivePrivateNetworkRequestPolicy(policies.ip_address_space,
policies.is_web_secure_context,
private_network_request_context);
}
Policy DerivePolicyForNonSecureContext(AddressSpace ip_address_space) {
switch (ip_address_space) {
case AddressSpace::kUnknown:
// Requests from the `unknown` address space are controlled separately
// because it is unclear why they happen in the first place. The goal is
// to reduce instances of this happening before enabling this feature.
return base::FeatureList::IsEnabled(
features::kBlockInsecurePrivateNetworkRequestsFromUnknown)
? Policy::kBlock
: Policy::kAllow;
case AddressSpace::kPrivate:
// Requests from the non secure contexts in the `private` address space
// to localhost are blocked only if the right feature is enabled.
// This is controlled separately because private network websites face
// additional hurdles compared to public websites. See crbug.com/1234044.
return base::FeatureList::IsEnabled(
features::kBlockInsecurePrivateNetworkRequestsFromPrivate)
? Policy::kBlock
: Policy::kWarn;
case AddressSpace::kPublic:
case AddressSpace::kLocal:
// Private network requests from non secure contexts are blocked if the
// secure context restriction is enabled in general.
//
// NOTE: We also set this when `ip_address_space` is `kLocal`, but that
// has no effect. Indeed, requests initiated from the local address space
// are never considered private network requests - they cannot target
// more-private address spaces.
return base::FeatureList::IsEnabled(
features::kBlockInsecurePrivateNetworkRequests)
? Policy::kBlock
: Policy::kWarn;
}
}
Policy DerivePolicyForSecureContext(AddressSpace ip_address_space) {
// The goal is to eliminate occurrences of this case as much as possible,
// before removing this special case.
if (ip_address_space == AddressSpace::kUnknown) {
return Policy::kAllow;
}
if (base::FeatureList::IsEnabled(
features::kPrivateNetworkAccessRespectPreflightResults)) {
return Policy::kPreflightBlock;
}
if (base::FeatureList::IsEnabled(
features::kPrivateNetworkAccessSendPreflights)) {
return Policy::kPreflightWarn;
}
return Policy::kAllow;
}
Policy ApplyFeatureStateToPolicy(FeatureState feature_state, Policy policy) {
switch (feature_state) {
// Feature disabled: allow all requests.
case FeatureState::kDisabled:
return Policy::kAllow;
// Feature enabled in warning-only mode. Downgrade `k*Block` to `k*Warn`.
case FeatureState::kWarningOnly:
switch (policy) {
case Policy::kBlock:
return Policy::kWarn;
case Policy::kPreflightBlock:
return Policy::kPreflightWarn;
default:
return policy;
}
// Fully enabled. Use `policy` as is.
case FeatureState::kEnabled:
return policy;
}
}
Policy DerivePrivateNetworkRequestPolicy(
AddressSpace ip_address_space,
bool is_web_secure_context,
RequestContext private_network_request_context) {
// Disable PNA checks entirely when running with `--disable-web-security`.
if (base::CommandLine::ForCurrentProcess()->HasSwitch(
switches::kDisableWebSecurity)) {
return Policy::kAllow;
}
FeatureState feature_state =
FeatureStateForContext(private_network_request_context);
Policy policy = is_web_secure_context
? DerivePolicyForSecureContext(ip_address_space)
: DerivePolicyForNonSecureContext(ip_address_space);
return ApplyFeatureStateToPolicy(feature_state, policy);
}
network::mojom::ClientSecurityStatePtr DeriveClientSecurityState(
const PolicyContainerPolicies& policies,
PrivateNetworkRequestContext private_network_request_context) {
return network::mojom::ClientSecurityState::New(
policies.cross_origin_embedder_policy, policies.is_web_secure_context,
policies.ip_address_space,
DerivePrivateNetworkRequestPolicy(policies,
private_network_request_context),
policies.document_isolation_policy);
}
// Special chrome schemes cannot directly be categorized in public/private/local
// address spaces using information from the network or the PolicyContainer. We
// have to classify them manually. In its default state an unhandled scheme will
// have an IPAddressSpace of kUnknown, which is equivalent to public.
// This means a couple of things:
// - They cannot embed anything private or local without being secure contexts
// and triggering a CORS preflight.
// - Private Network Access does not prevent them being embedded by less private
// content.
// - It pollutes metrics since kUnknown could also mean a missed edge case.
// To address these issues we list here a number of schemes that should be
// considered local.
// TODO(titouan): It might be better to have these schemes (and in general
// other schemes such as data: or blob:) handled directly by the URLLoaders.
// Investigate on whether this is worth doing.
AddressSpace IPAddressSpaceForSpecialScheme(const GURL& url,
ContentBrowserClient* client) {
// This only handles schemes that are known to the content/ layer.
// List here: content/public/common/url_constants.cc.
const char* special_content_schemes[] = {
kChromeDevToolsScheme,
kChromeUIScheme,
kChromeUIUntrustedScheme,
#if BUILDFLAG(IS_CHROMEOS_ASH)
kExternalFileScheme,
#endif
};
for (auto* scheme : special_content_schemes) {
if (url.SchemeIs(scheme)) {
return AddressSpace::kLocal;
}
}
// Some of these schemes are only known to the embedder. Query the embedder
// for these.
if (!client) {
return AddressSpace::kUnknown;
}
return client->DetermineAddressSpaceFromURL(url);
}
AddressSpace CalculateIPAddressSpace(
const GURL& url,
network::mojom::URLResponseHead* response_head,
ContentBrowserClient* client) {
// Determine the IPAddressSpace, based on the IP address and the response
// headers received.
std::optional<network::CalculateClientAddressSpaceParams> params =
std::nullopt;
if (response_head) {
std::optional<network::mojom::IPAddressSpace> client_address_space;
if (response_head->was_fetched_via_service_worker &&
response_head->client_address_space !=
network::mojom::IPAddressSpace::kUnknown) {
client_address_space = response_head->client_address_space;
}
params.emplace<network::CalculateClientAddressSpaceParams>({
.client_address_space_inherited_from_service_worker =
client_address_space,
.parsed_headers = &response_head->parsed_headers,
.remote_endpoint = &response_head->remote_endpoint,
});
}
AddressSpace computed_ip_address_space =
network::CalculateClientAddressSpace(url, params);
if (computed_ip_address_space != AddressSpace::kUnknown) {
return computed_ip_address_space;
}
return IPAddressSpaceForSpecialScheme(url, client);
}
network::mojom::PrivateNetworkRequestPolicy OverrideBlockWithWarn(
network::mojom::PrivateNetworkRequestPolicy policy) {
switch (policy) {
case network::mojom::PrivateNetworkRequestPolicy::kWarn:
return network::mojom::PrivateNetworkRequestPolicy::kBlock;
case network::mojom::PrivateNetworkRequestPolicy::kPreflightWarn:
return network::mojom::PrivateNetworkRequestPolicy::kPreflightBlock;
default:
return policy;
}
}
} // namespace content