pcs 0.8.4

/* Copyright (c) Fortanix, Inc.
 *
 * 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 http://mozilla.org/MPL/2.0/.
 */
use crate::{io, Error, WriteOptions};
use crate::{DcapArtifactIssuer, Unverified, VerificationType, Verified};
use pkix::pem::PEM_CRL;
use serde::{Deserialize, Serialize};
use std::borrow::Cow;
use std::path::PathBuf;

#[cfg(feature = "verify")]
use {mbedtls::x509::{Certificate, Crl}, std::ops::Deref};

#[derive(Serialize, Deserialize, Clone, Debug)]
enum CrlType {
    Pem(String),
    Der(Vec<u8>),
}

/// Type that represents the Root CA CRL within the Intel PCS infrastructures.
#[derive(Serialize, Deserialize, Clone, Debug)]
pub struct RootCaCrl<V: VerificationType = Verified> {
    /// The CRL itself in PEM format
    crl: CrlType,
    #[serde(skip_serializing)]
    _type: V,
}

impl RootCaCrl<Unverified> {
    pub fn new(crl: &[u8]) -> Result<Self, Error> {
        let crl = Self {
            crl: CrlType::Der(Vec::from(crl)),
            _type: Unverified,
        };
        Ok(crl)
    }

    pub fn new_from_pem(crl_pem: &str) -> Result<Self, Error> {
        let crl = Self {
            crl: CrlType::Pem(crl_pem.to_string()),
            _type: Unverified,
        };
        Ok(crl)
    }

    #[cfg(feature = "verify")]
    pub fn verify<B: Deref<Target = [u8]>>(
        self,
        trusted_root_certs: &[B],
    ) -> Result<RootCaCrl<Verified>, Error> {
        use mbedtls::x509::Crl;

        let crl = match &self.crl {
            CrlType::Pem(pem) => crate::as_mbedtls_crl(pem)?,
            CrlType::Der(der) => {
                let mut c = Crl::new();
                c.push_from_der(der.as_slice()).map_err(|_| Error::InvalidCrlFormat)?;
                c
            }
        };

        let crl_signature = crl.signature().map_err(|e| Error::InvalidCrl(e))?;
        let crl_tbs = crl.tbs_raw().map_err(|e| Error::InvalidCrl(e))?;
        let mut hash = [0u8; 32];
        mbedtls::hash::Md::hash(mbedtls::hash::Type::Sha256, &crl_tbs, &mut hash).unwrap();

        // Since we have no way to find the correct CA using its key identifier/serial,
        // then we just iterate the root certificates manually. If any of it gives OK
        // verification, then it is the correct CRL
        let root_ca_found = trusted_root_certs.iter().find_map(|cert_der| {
            Certificate::from_der(cert_der).map(|mut cert| {
                let verify = cert.public_key_mut()
                    .verify(mbedtls::hash::Type::Sha256, &hash, &crl_signature)
                    .is_ok();

                if verify {
                    Some(cert)
                } else {
                    None
                }
            }).unwrap_or(None)
        });

        if let Some(_) = root_ca_found {
            let RootCaCrl { crl, .. } = self;
            Ok(RootCaCrl::<Verified> {
                crl,
                _type: Verified,
            })
        } else {
            Err(Error::IncorrectCA)
        }
    }

    pub fn read_from_file(input_dir: &str) -> Result<Self, Error> {
        let filename = crate::PckCrl::<Unverified>::filename_from_ca(DcapArtifactIssuer::SGXRootCA);
        let crl: Self = io::read_from_file(input_dir, &filename)?;
        Ok(crl)
    }
}

impl<V: VerificationType> RootCaCrl<V> {
    pub fn write_to_file(
        &self,
        output_dir: &str,
        option: WriteOptions,
    ) -> Result<Option<PathBuf>, Error> {
        let filename = crate::PckCrl::<Unverified>::filename_from_ca(DcapArtifactIssuer::SGXRootCA);
        io::write_to_file(&self, output_dir, &filename, option)
    }

    pub fn crl_as_der(&self) -> Result<Vec<u8>, Error> {
        match &self.crl {
            CrlType::Pem(pem) => pkix::pem::pem_to_der(&pem, Some(PEM_CRL)).ok_or(Error::InvalidCrlFormat),
            CrlType::Der(der) => Ok(der.clone()),
        }
    }

    pub fn crl_as_pem<'a>(&'a self) -> Cow<'a, String> {
        match &self.crl {
            CrlType::Pem(pem) => Cow::Borrowed(pem),
            CrlType::Der(der) => Cow::Owned(pkix::pem::der_to_pem(der, PEM_CRL)),
        }
    }
}

#[cfg(feature = "verify")]
impl RootCaCrl<Verified> {
    pub fn push_to_crl_list(&self, out_crl: &mut Crl) -> Result<(), Error> {
        use crate::CString;
        match &self.crl {
            CrlType::Pem(pem) => {
                let c = CString::new(pem.as_bytes()).map_err(|_| Error::InvalidCrlFormat)?;
                out_crl.push_from_pem(c.as_bytes_with_nul()).map_err(|_| Error::InvalidCrlFormat)
            }
            CrlType::Der(der) => out_crl.push_from_der(der.as_slice()).map_err(|_| Error::InvalidCrlFormat)
        }
    }
}

#[cfg(test)]
#[cfg(feature = "verify")]
mod tests {
    use tempdir::TempDir;
    use crate::{Unverified, WriteOptionsBuilder};
    use super::RootCaCrl;

    #[test]
    fn root_ca_crl_parse() {
        let root_ca = include_bytes!("../tests/data/root_SGX_CA_der.cert");
        let root_cas = [&root_ca[..]];

        let crl_der = include_bytes!("../tests/data/IntelSGXRootCA.der");
        let root_ca_crl = RootCaCrl::new(crl_der).unwrap();

        let root_ca_crl = root_ca_crl.verify(&root_cas).unwrap();

        let temp_dir = TempDir::new("tempdir").unwrap();
        let path = temp_dir.path().as_os_str().to_str().unwrap();
        root_ca_crl.write_to_file(&path, WriteOptionsBuilder::new().build()).unwrap();

        let _ = RootCaCrl::<Unverified>::read_from_file(path).unwrap().verify(&root_cas).unwrap();
    }

    #[test]
    fn root_ca_crl_der_conversion() {
        let root_ca = include_bytes!("../tests/data/root_SGX_CA_der.cert");
        let root_cas = [&root_ca[..]];

        let crl_pem = include_str!("../tests/data/IntelSGXRootCA.crl");
        let root_ca_crl = RootCaCrl::new_from_pem(crl_pem).unwrap();

        let der = root_ca_crl.crl_as_der().unwrap();

        let recreate_root_ca_crl = RootCaCrl::new(&der).unwrap();
        let recreated_crl = recreate_root_ca_crl.verify(&root_cas).unwrap();

        let pem_again = recreated_crl.crl_as_pem();
        let recreate_root_ca_crl = RootCaCrl::new_from_pem(pem_again.as_str()).unwrap();
        recreate_root_ca_crl.verify(&root_cas).unwrap();
    }
}