diff options
Diffstat (limited to 'src/verify_cert.rs')
| -rw-r--r-- | src/verify_cert.rs | 120 |
1 files changed, 89 insertions, 31 deletions
diff --git a/src/verify_cert.rs b/src/verify_cert.rs index c68e6cf..fe7ef9d 100644 --- a/src/verify_cert.rs +++ b/src/verify_cert.rs @@ -12,9 +12,14 @@ // ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF // OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. +use core::default::Default; + use crate::{ + budget::Budget, cert::{self, Cert, EndEntityOrCa}, - der, name, signed_data, time, Error, SignatureAlgorithm, TrustAnchor, + der, equal, + error::ErrorExt, + name, signed_data, time, Error, SignatureAlgorithm, TrustAnchor, }; pub fn build_chain( @@ -24,8 +29,30 @@ pub fn build_chain( intermediate_certs: &[&[u8]], cert: &Cert, time: time::Time, +) -> Result<(), ErrorExt> { + build_chain_inner( + required_eku_if_present, + supported_sig_algs, + trust_anchors, + intermediate_certs, + cert, + time, + 0, + &mut Budget::default(), + ) +} + +#[allow(clippy::too_many_arguments)] +fn build_chain_inner( + required_eku_if_present: KeyPurposeId, + supported_sig_algs: &[&SignatureAlgorithm], + trust_anchors: &[TrustAnchor], + intermediate_certs: &[&[u8]], + cert: &Cert, + time: time::Time, sub_ca_count: usize, -) -> Result<(), Error> { + budget: &mut Budget, +) -> Result<(), ErrorExt> { let used_as_ca = used_as_ca(&cert.ee_or_ca); check_issuer_independent_properties( @@ -43,7 +70,7 @@ pub fn build_chain( const MAX_SUB_CA_COUNT: usize = 6; if sub_ca_count >= MAX_SUB_CA_COUNT { - return Err(Error::UnknownIssuer); + return Err(Error::UnknownIssuer.into()); } } UsedAsCa::No => { @@ -55,47 +82,46 @@ pub fn build_chain( match loop_while_non_fatal_error(trust_anchors, |trust_anchor: &TrustAnchor| { let trust_anchor_subject = untrusted::Input::from(trust_anchor.subject); - if cert.issuer != trust_anchor_subject { - return Err(Error::UnknownIssuer); + if !equal(cert.issuer, trust_anchor_subject) { + return Err(Error::UnknownIssuer.into()); } - let name_constraints = trust_anchor.name_constraints.map(untrusted::Input::from); - - untrusted::read_all_optional(name_constraints, Error::BadDer, |value| { - name::check_name_constraints(value, &cert) - })?; - let trust_anchor_spki = untrusted::Input::from(trust_anchor.spki); // TODO: check_distrust(trust_anchor_subject, trust_anchor_spki)?; - check_signatures(supported_sig_algs, cert, trust_anchor_spki)?; + check_signatures(supported_sig_algs, cert, trust_anchor_spki, budget)?; + + check_signed_chain_name_constraints(cert, trust_anchor)?; Ok(()) }) { Ok(()) => { return Ok(()); } - Err(..) => { + Err(e) => { + if e.is_fatal() { + return Err(e); + } // If the error is not fatal, then keep going. } } loop_while_non_fatal_error(intermediate_certs, |cert_der| { let potential_issuer = - cert::parse_cert(untrusted::Input::from(*cert_der), EndEntityOrCa::Ca(&cert))?; + cert::parse_cert(untrusted::Input::from(cert_der), EndEntityOrCa::Ca(cert))?; - if potential_issuer.subject != cert.issuer { - return Err(Error::UnknownIssuer); + if !equal(potential_issuer.subject, cert.issuer) { + return Err(Error::UnknownIssuer.into()); } // Prevent loops; see RFC 4158 section 5.2. let mut prev = cert; loop { - if potential_issuer.spki.value() == prev.spki.value() - && potential_issuer.subject == prev.subject + if equal(potential_issuer.spki.value(), prev.spki.value()) + && equal(potential_issuer.subject, prev.subject) { - return Err(Error::UnknownIssuer); + return Err(Error::UnknownIssuer.into()); } match &prev.ee_or_ca { EndEntityOrCa::EndEntity => { @@ -107,16 +133,13 @@ pub fn build_chain( } } - untrusted::read_all_optional(potential_issuer.name_constraints, Error::BadDer, |value| { - name::check_name_constraints(value, &cert) - })?; - let next_sub_ca_count = match used_as_ca { UsedAsCa::No => sub_ca_count, UsedAsCa::Yes => sub_ca_count + 1, }; - build_chain( + budget.consume_build_chain_call()?; + build_chain_inner( required_eku_if_present, supported_sig_algs, trust_anchors, @@ -124,6 +147,7 @@ pub fn build_chain( &potential_issuer, time, next_sub_ca_count, + budget, ) }) } @@ -132,10 +156,12 @@ fn check_signatures( supported_sig_algs: &[&SignatureAlgorithm], cert_chain: &Cert, trust_anchor_key: untrusted::Input, -) -> Result<(), Error> { + budget: &mut Budget, +) -> Result<(), ErrorExt> { let mut spki_value = trust_anchor_key; let mut cert = cert_chain; loop { + budget.consume_signature()?; signed_data::verify_signed_data(supported_sig_algs, spki_value, &cert.signed_data)?; // TODO: check revocation @@ -154,6 +180,32 @@ fn check_signatures( Ok(()) } +fn check_signed_chain_name_constraints( + cert_chain: &Cert, + trust_anchor: &TrustAnchor, +) -> Result<(), Error> { + let mut cert = cert_chain; + let mut name_constraints = trust_anchor.name_constraints.map(untrusted::Input::from); + + loop { + untrusted::read_all_optional(name_constraints, Error::BadDer, |value| { + name::check_name_constraints(value, cert) + })?; + + match &cert.ee_or_ca { + EndEntityOrCa::Ca(child_cert) => { + name_constraints = cert.name_constraints; + cert = child_cert; + } + EndEntityOrCa::EndEntity => { + break; + } + } + } + + Ok(()) +} + fn check_issuer_independent_properties( cert: &Cert, time: time::Time, @@ -302,7 +354,7 @@ fn check_eku( Some(input) => { loop { let value = der::expect_tag_and_get_value(input, der::Tag::OID)?; - if value == required_eku_if_present.oid_value { + if equal(value, required_eku_if_present.oid_value) { input.skip_to_end(); break; } @@ -322,7 +374,10 @@ fn check_eku( // important that id-kp-OCSPSigning is explicit so that a normal // end-entity certificate isn't able to sign trusted OCSP responses // for itself or for other certificates issued by its issuing CA. - if required_eku_if_present.oid_value == EKU_OCSP_SIGNING.oid_value { + if equal( + required_eku_if_present.oid_value, + EKU_OCSP_SIGNING.oid_value, + ) { return Err(Error::RequiredEkuNotFound); } @@ -333,8 +388,8 @@ fn check_eku( fn loop_while_non_fatal_error<V>( values: V, - f: impl Fn(V::Item) -> Result<(), Error>, -) -> Result<(), Error> + mut f: impl FnMut(V::Item) -> Result<(), ErrorExt>, +) -> Result<(), ErrorExt> where V: IntoIterator, { @@ -343,10 +398,13 @@ where Ok(()) => { return Ok(()); } - Err(..) => { + Err(e) => { + if e.is_fatal() { + return Err(e); + } // If the error is not fatal, then keep going. } } } - Err(Error::UnknownIssuer) + Err(Error::UnknownIssuer.into()) } |