Function apple_codesign::derive_designated_requirements

pub fn derive_designated_requirements(
    cert: &CapturedX509Certificate,
    identifier: Option<String>
) -> Result<Option<CodeRequirementExpression<'static>>, AppleCodesignError>

Derive a designated requirements expression given a code signing certificate.

This function figures out what the run-time requirements of a signed binary should be given its code signing certificate.

We determine the flavor of Apple code signing certificate in use and apply an appropriate requirements policy. We strive for behavior equivalence with Apple’s codesign tool.

Examples found in repository

src/macho_signing.rs (line 619)

    pub fn create_special_blobs(
        &self,
        settings: &SigningSettings,
        is_executable: bool,
    ) -> Result<Vec<(CodeSigningSlot, BlobData<'static>)>, AppleCodesignError> {
        let mut res = Vec::new();

        let mut requirements = CodeRequirements::default();

        match settings.designated_requirement(SettingsScope::Main) {
            DesignatedRequirementMode::Auto => {
                // If we are using an Apple-issued cert, this should automatically
                // derive appropriate designated requirements.
                if let Some((_, cert)) = settings.signing_key() {
                    info!("attempting to derive code requirements from signing certificate");
                    let identifier = Some(
                        settings
                            .binary_identifier(SettingsScope::Main)
                            .ok_or(AppleCodesignError::NoIdentifier)?
                            .to_string(),
                    );

                    if let Some(expr) = derive_designated_requirements(cert, identifier)? {
                        requirements.push(expr);
                    }
                }
            }
            DesignatedRequirementMode::Explicit(exprs) => {
                info!("using provided code requirements");
                for expr in exprs {
                    requirements.push(CodeRequirementExpression::from_bytes(expr)?.0);
                }
            }
        }

        // Always emit a RequirementSet blob, even if empty. Without it, validation fails
        // with `the sealed resource directory is invalid`.
        let mut blob = RequirementSetBlob::default();

        if !requirements.is_empty() {
            info!("code requirements: {}", requirements);
            requirements.add_to_requirement_set(&mut blob, RequirementType::Designated)?;
        }

        res.push((CodeSigningSlot::RequirementSet, blob.into()));

        if let Some(entitlements) = settings.entitlements_xml(SettingsScope::Main)? {
            info!("adding entitlements XML");
            let blob = EntitlementsBlob::from_string(&entitlements);

            res.push((CodeSigningSlot::Entitlements, blob.into()));
        }

        // The DER encoded entitlements weren't always present in the signature. The feature
        // appears to have been introduced in macOS 10.14 and is the default behavior as of
        // macOS 12 "when signing for all platforms." `codesign` appears to add the DER
        // representation whenever entitlements are present, but only if the current binary is
        // an executable (.filetype == MH_EXECUTE).
        if is_executable {
            if let Some(value) = settings.entitlements_plist(SettingsScope::Main) {
                info!("adding entitlements DER");
                let blob = EntitlementsDerBlob::from_plist(value)?;

                res.push((CodeSigningSlot::EntitlementsDer, blob.into()));
            }
        }

        Ok(res)
    }