servo/components/script/dom/security/csp.rs

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

use std::borrow::Cow;

/// Used to determine which inline check to run
pub use content_security_policy::InlineCheckType;
/// Used to report CSP violations in Fetch handlers
pub use content_security_policy::Violation;
use content_security_policy::{
    CheckResult, CspList, Destination, Element as CspElement, Initiator, NavigationCheckType,
    Origin, ParserMetadata, PolicyDisposition, PolicySource, Request, Response as CspResponse,
    ViolationResource,
};
use http::header::{HeaderMap, HeaderValue, ValueIter};
use hyper_serde::Serde;
use js::rust::describe_scripted_caller;
use log::warn;
use servo_constellation_traits::{LoadData, LoadOrigin};
use url::Url;

use super::csppolicyviolationreport::CSPViolationReportBuilder;
use crate::dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
use crate::dom::bindings::codegen::UnionTypes::TrustedScriptOrString;
use crate::dom::bindings::inheritance::Castable;
use crate::dom::bindings::refcounted::Trusted;
use crate::dom::bindings::root::DomRoot;
use crate::dom::element::Element;
use crate::dom::globalscope::GlobalScope;
use crate::dom::node::{Node, NodeTraits};
use crate::dom::reporting::reportingobserver::ReportingObserver;
use crate::dom::security::cspviolationreporttask::CSPViolationReportTask;
use crate::dom::trustedtypes::trustedscript::TrustedScript;
use crate::dom::window::Window;

pub(crate) trait CspReporting {
    fn is_js_evaluation_allowed(&self, global: &GlobalScope, source: &str) -> bool;
    fn is_wasm_evaluation_allowed(&self, global: &GlobalScope) -> bool;
    fn should_navigation_request_be_blocked(
        &self,
        cx: &mut js::context::JSContext,
        global: &GlobalScope,
        load_data: &mut LoadData,
        element: Option<&Element>,
    ) -> bool;
    fn should_navigation_response_to_navigation_request_be_blocked(
        &self,
        window: &Window,
        url: Url,
        self_origin: &url::Origin,
    ) -> bool;
    fn should_elements_inline_type_behavior_be_blocked(
        &self,
        global: &GlobalScope,
        el: &Element,
        type_: InlineCheckType,
        source: &str,
        current_line: u32,
    ) -> bool;
    fn is_trusted_type_policy_creation_allowed(
        &self,
        global: &GlobalScope,
        policy_name: &str,
        created_policy_names: &[&str],
    ) -> bool;
    fn does_sink_type_require_trusted_types(
        &self,
        sink_group: &str,
        include_report_only_policies: bool,
    ) -> bool;
    fn should_sink_type_mismatch_violation_be_blocked_by_csp(
        &self,
        global: &GlobalScope,
        sink: &str,
        sink_group: &str,
        source: &str,
    ) -> bool;
    fn is_base_allowed_for_document(
        &self,
        global: &GlobalScope,
        base: &url::Url,
        self_origin: &url::Origin,
    ) -> bool;
    fn concatenate(self, new_csp_list: Option<CspList>) -> Option<CspList>;
}

impl CspReporting for Option<CspList> {
    /// <https://www.w3.org/TR/CSP/#can-compile-strings>
    fn is_js_evaluation_allowed(&self, global: &GlobalScope, source: &str) -> bool {
        let Some(csp_list) = self else {
            return true;
        };

        let (is_js_evaluation_allowed, violations) = csp_list.is_js_evaluation_allowed(source);

        global.report_csp_violations(violations, None, None);

        is_js_evaluation_allowed == CheckResult::Allowed
    }

    /// <https://www.w3.org/TR/CSP/#can-compile-wasm-bytes>
    fn is_wasm_evaluation_allowed(&self, global: &GlobalScope) -> bool {
        let Some(csp_list) = self else {
            return true;
        };

        let (is_wasm_evaluation_allowed, violations) = csp_list.is_wasm_evaluation_allowed();

        global.report_csp_violations(violations, None, None);

        is_wasm_evaluation_allowed == CheckResult::Allowed
    }

    /// <https://www.w3.org/TR/CSP/#should-block-navigation-request>
    fn should_navigation_request_be_blocked(
        &self,
        cx: &mut js::context::JSContext,
        global: &GlobalScope,
        load_data: &mut LoadData,
        element: Option<&Element>,
    ) -> bool {
        let Some(csp_list) = self else {
            return false;
        };
        let mut request = Request {
            url: load_data.url.clone().into_url(),
            // TODO: Figure out how to propagate redirect data from LoadData into here
            current_url: load_data.url.clone().into_url(),
            origin: match &load_data.load_origin {
                LoadOrigin::Script(origin) => origin.immutable().clone().into_url_origin(),
                _ => Origin::new_opaque(),
            },
            // TODO: populate this field correctly
            redirect_count: 0,
            destination: Destination::None,
            initiator: Initiator::None,
            nonce: "".to_owned(),
            integrity_metadata: "".to_owned(),
            parser_metadata: ParserMetadata::None,
        };
        // TODO: set correct navigation check type for form submission if applicable
        let (result, violations) = csp_list.should_navigation_request_be_blocked(
            &mut request,
            NavigationCheckType::Other,
            |script_source| {
                // Step 4. Let convertedScriptSource be the result of executing
                // Process value with a default policy algorithm, with the following arguments:
                TrustedScript::get_trusted_type_compliant_string(
                    cx,
                    global,
                    TrustedScriptOrString::String(script_source.into()),
                    "Location href",
                )
                .ok()
                .map(|s| s.into())
            },
        );

        // In case trusted types processing has changed the Javascript contents
        load_data.url = request.url.into();

        global.report_csp_violations(violations, element, None);

        result == CheckResult::Blocked
    }

    /// <https://w3c.github.io/webappsec-csp/#should-block-navigation-response>
    fn should_navigation_response_to_navigation_request_be_blocked(
        &self,
        window: &Window,
        url: Url,
        self_origin: &url::Origin,
    ) -> bool {
        let Some(csp_list) = self else {
            return false;
        };

        let mut window_proxy = window.window_proxy();
        let mut parent_navigable_origins = vec![];
        loop {
            // Same-origin parents can go via their own script-thread (fast-path)
            if let Some(container_element) = window_proxy.frame_element() {
                let container_document = container_element.owner_document();
                let parent_origin = Url::parse(
                    &container_document
                        .origin()
                        .immutable()
                        .ascii_serialization(),
                )
                .expect("Must always be able to parse document origin");
                parent_navigable_origins.push(parent_origin);
                window_proxy = container_document.window().window_proxy();
                continue;
            }
            // Cross-origin parents go via the constellation (slower)
            if let Some(parent_proxy) = window_proxy.parent() {
                let Some(parent_origin) = parent_proxy.document_origin() else {
                    break;
                };
                let parent_origin = Url::parse(&parent_origin)
                    .expect("Must always be able to parse document origin");
                parent_navigable_origins.push(parent_origin);
                window_proxy = DomRoot::from_ref(parent_proxy);
                continue;
            }
            // We don't have a parent, hence we stop traversing
            break;
        }

        let (is_navigation_response_blocked, violations) = csp_list
            .should_navigation_response_to_navigation_request_be_blocked(
                &CspResponse {
                    url,
                    redirect_count: 0,
                },
                self_origin,
                &parent_navigable_origins,
            );

        window
            .as_global_scope()
            .report_csp_violations(violations, None, None);

        is_navigation_response_blocked == CheckResult::Blocked
    }

    /// <https://www.w3.org/TR/CSP/#should-block-inline>
    fn should_elements_inline_type_behavior_be_blocked(
        &self,
        global: &GlobalScope,
        el: &Element,
        type_: InlineCheckType,
        source: &str,
        current_line: u32,
    ) -> bool {
        let Some(csp_list) = self else {
            return false;
        };
        let element = CspElement {
            nonce: if el.is_nonceable() {
                Some(Cow::Owned(el.nonce_value().trim().to_owned()))
            } else {
                None
            },
        };
        let (result, violations) =
            csp_list.should_elements_inline_type_behavior_be_blocked(&element, type_, source);

        let source_position = el.compute_source_position(current_line.saturating_sub(2).max(1));

        global.report_csp_violations(violations, Some(el), Some(source_position));

        result == CheckResult::Blocked
    }

    /// <https://w3c.github.io/trusted-types/dist/spec/#should-block-create-policy>
    fn is_trusted_type_policy_creation_allowed(
        &self,
        global: &GlobalScope,
        policy_name: &str,
        created_policy_names: &[&str],
    ) -> bool {
        let Some(csp_list) = self else {
            return true;
        };

        let (allowed_by_csp, violations) =
            csp_list.is_trusted_type_policy_creation_allowed(policy_name, created_policy_names);

        global.report_csp_violations(violations, None, None);

        allowed_by_csp == CheckResult::Allowed
    }

    /// <https://w3c.github.io/trusted-types/dist/spec/#abstract-opdef-does-sink-type-require-trusted-types>
    fn does_sink_type_require_trusted_types(
        &self,
        sink_group: &str,
        include_report_only_policies: bool,
    ) -> bool {
        let Some(csp_list) = self else {
            return false;
        };

        csp_list.does_sink_type_require_trusted_types(sink_group, include_report_only_policies)
    }

    /// <https://w3c.github.io/trusted-types/dist/spec/#should-block-sink-type-mismatch>
    fn should_sink_type_mismatch_violation_be_blocked_by_csp(
        &self,
        global: &GlobalScope,
        sink: &str,
        sink_group: &str,
        source: &str,
    ) -> bool {
        let Some(csp_list) = self else {
            return false;
        };

        let (allowed_by_csp, violations) = csp_list
            .should_sink_type_mismatch_violation_be_blocked_by_csp(sink, sink_group, source);

        global.report_csp_violations(violations, None, None);

        allowed_by_csp == CheckResult::Blocked
    }

    /// <https://www.w3.org/TR/CSP3/#allow-base-for-document>
    fn is_base_allowed_for_document(
        &self,
        global: &GlobalScope,
        base: &url::Url,
        self_origin: &url::Origin,
    ) -> bool {
        let Some(csp_list) = self else {
            return true;
        };

        let (is_base_allowed, violations) =
            csp_list.is_base_allowed_for_document(base, self_origin);

        global.report_csp_violations(violations, None, None);

        is_base_allowed == CheckResult::Allowed
    }

    fn concatenate(self, new_csp_list: Option<CspList>) -> Option<CspList> {
        let Some(new_csp_list) = new_csp_list else {
            return self;
        };

        match self {
            None => Some(new_csp_list),
            Some(mut old_csp_list) => {
                old_csp_list.append(new_csp_list);
                Some(old_csp_list)
            },
        }
    }
}

pub(crate) struct SourcePosition {
    pub(crate) source_file: String,
    pub(crate) line_number: u32,
    pub(crate) column_number: u32,
}

pub(crate) trait GlobalCspReporting {
    fn report_csp_violations(
        &self,
        violations: Vec<Violation>,
        element: Option<&Element>,
        source_position: Option<SourcePosition>,
    );
}

#[expect(unsafe_code)]
fn compute_scripted_caller_source_position() -> SourcePosition {
    match unsafe { describe_scripted_caller(*GlobalScope::get_cx()) } {
        Ok(scripted_caller) => SourcePosition {
            source_file: scripted_caller.filename,
            line_number: scripted_caller.line,
            column_number: scripted_caller.col + 1,
        },
        Err(()) => SourcePosition {
            source_file: String::new(),
            line_number: 0,
            column_number: 0,
        },
    }
}

/// <https://www.w3.org/TR/CSP3/#obtain-violation-blocked-uri>
fn obtain_blocked_uri_for_violation_resource_with_sample(
    resource: ViolationResource,
) -> (Option<String>, String) {
    // Step 1. Assert: resource is a URL or a string.
    //
    // Already done since we destructure the relevant enum value

    // Step 3. Return resource.
    match resource {
        ViolationResource::Inline { sample } => (sample, "inline".to_owned()),
        // Step 2. If resource is a URL, return the result of executing § 5.4 Strip URL for use in reports on resource.
        ViolationResource::Url(url) => (
            Some(String::new()),
            ReportingObserver::strip_url_for_reports(url.into()),
        ),
        ViolationResource::TrustedTypePolicy { sample } => {
            (Some(sample), "trusted-types-policy".to_owned())
        },
        ViolationResource::TrustedTypeSink { sample } => {
            (Some(sample), "trusted-types-sink".to_owned())
        },
        ViolationResource::Eval { sample } => (sample, "eval".to_owned()),
        ViolationResource::WasmEval => (None, "wasm-eval".to_owned()),
    }
}

impl GlobalCspReporting for GlobalScope {
    /// <https://www.w3.org/TR/CSP/#report-violation>
    fn report_csp_violations(
        &self,
        violations: Vec<Violation>,
        element: Option<&Element>,
        source_position: Option<SourcePosition>,
    ) {
        if violations.is_empty() {
            return;
        }
        warn!("Reporting CSP violations: {:?}", violations);
        let source_position =
            source_position.unwrap_or_else(compute_scripted_caller_source_position);
        for violation in violations {
            let (sample, resource) =
                obtain_blocked_uri_for_violation_resource_with_sample(violation.resource);
            let report = CSPViolationReportBuilder::default()
                .resource(resource)
                .sample(sample)
                .effective_directive(violation.directive.name)
                .original_policy(violation.policy.to_string())
                .report_only(violation.policy.disposition == PolicyDisposition::Report)
                .source_file(source_position.source_file.clone())
                .line_number(source_position.line_number)
                .column_number(source_position.column_number)
                .build(self);
            // Step 1: Let global be violation’s global object.
            // We use `self` as `global`;
            // Step 2: Let target be violation’s element.
            let target = element.and_then(|event_target| {
                // Step 3.1: If target is not null, and global is a Window,
                // and target’s shadow-including root is not global’s associated Document, set target to null.
                if let Some(window) = self.downcast::<Window>() {
                    // If a node is connected, its owner document is always the shadow-including root.
                    // If it isn't connected, then it also doesn't have a corresponding document, hence
                    // it can't be this document.
                    if event_target.upcast::<Node>().owner_document() != window.Document() {
                        return None;
                    }
                }
                Some(event_target)
            });
            let target = match target {
                // Step 3.2: If target is null:
                None => {
                    // Step 3.2.2: If target is a Window, set target to target’s associated Document.
                    if let Some(window) = self.downcast::<Window>() {
                        Trusted::new(window.Document().upcast())
                    } else {
                        // Step 3.2.1: Set target to violation’s global object.
                        Trusted::new(self.upcast())
                    }
                },
                Some(event_target) => Trusted::new(event_target.upcast()),
            };
            // Step 3: Queue a task to run the following steps:
            let task =
                CSPViolationReportTask::new(Trusted::new(self), target, report, violation.policy);
            self.task_manager()
                .dom_manipulation_task_source()
                .queue(task);
        }
    }
}

fn parse_and_potentially_append_to_csp_list(
    old_csp_list: Option<CspList>,
    csp_header_iter: ValueIter<HeaderValue>,
    disposition: PolicyDisposition,
) -> Option<CspList> {
    let mut csp_list = old_csp_list;
    for header in csp_header_iter {
        // This silently ignores the CSP if it contains invalid Unicode.
        // We should probably report an error somewhere.
        let new_csp_list = header
            .to_str()
            .ok()
            .map(|value| CspList::parse(value, PolicySource::Header, disposition));
        csp_list = csp_list.concatenate(new_csp_list);
    }
    csp_list
}

/// <https://www.w3.org/TR/CSP/#parse-response-csp>
pub(crate) fn parse_csp_list_from_metadata(headers: &Option<Serde<HeaderMap>>) -> Option<CspList> {
    let headers = headers.as_ref()?;
    let csp_enforce_list = parse_and_potentially_append_to_csp_list(
        None,
        headers.get_all("content-security-policy").iter(),
        PolicyDisposition::Enforce,
    );

    parse_and_potentially_append_to_csp_list(
        csp_enforce_list,
        headers
            .get_all("content-security-policy-report-only")
            .iter(),
        PolicyDisposition::Report,
    )
}