Address misc security issues (#47)

* Limit the size of attestation certs

* Use authority returned from x509 approval response

* x509 authorization checks authority for local-db mode

* Fix test configs

rustica-agent-cli/src/config/mod.rs

@@ -313,7 +313,7 @@ pub async fn configure() -> Result<RusticaAgentAction, ConfigurationError> {
         return gitconfig::configure_git_config(git_config);
     }
 
-    if let Some(x509_config) = matches.subcommand_matches("refresh-x509") {
+    if let Some(x509_config) = matches.subcommand_matches("refresh-attested-x509") {
         return refresh_attested_x509_certificate::configure_refresh_x509_certificate(x509_config)
             .await;
     }

rustica/migrations/2023-04-10-043746_add_x509_by_serial/up.sql

@@ -1,7 +1,8 @@
 -- Your SQL goes here
 CREATE TABLE x509_authorizations (
-	user TEXT NOT NULL,
+    user TEXT NOT NULL,
     hsm_serial TEXT NOT NULL,
     require_touch BOOLEAN NOT NULL,
+    authority TEXT NOT NULL,
     PRIMARY KEY (user, hsm_serial)
-);
+);

rustica/src/auth/database.rs

@@ -181,7 +181,7 @@ impl LocalDatabase {
 
         let authorization: Vec<_> = {
             use schema::x509_authorizations::dsl::*;
-            let results = x509_authorizations.filter(user.eq(mtls_user).and(hsm_serial.eq(att_serial.to_string())))
+            let results = x509_authorizations.filter(user.eq(mtls_user).and(authority.eq(&auth_props.authority).and(hsm_serial.eq(att_serial.to_string()))))
                 .load::<models::X509Authorization>(&mut conn)
                 .expect("Error loading authorized hosts");
 

rustica/src/auth/database/models.rs

@@ -63,4 +63,5 @@ pub struct X509Authorization {
     pub user: String,
     pub hsm_serial: String,
     pub require_touch: bool,
-}
+    pub authority: String,
+}

rustica/src/auth/database/schema.rs

@@ -75,6 +75,7 @@ table! {
         user -> Text,
         hsm_serial -> Text,
         require_touch -> Bool,
+        authority -> Text,
     }
 }
 

rustica/src/auth/external.rs

@@ -270,9 +270,7 @@ impl AuthServer {
         auth_props: &X509AuthorizationRequestProperties,
     ) -> Result<X509Authorization, AuthorizationError> {
         let mut authorization_request = HashMap::new();
-        // TODO: This is an anachronistic hold over and should be updated from
-        // quorum_mtls to rustica_mtls or rustica_x509
-        authorization_request.insert(format!("type"), "quorum_mtls".to_string());
+        authorization_request.insert(format!("type"), "rustica_mtls".to_string());
         authorization_request.insert("authority".to_string(), auth_props.authority.clone());
 
         // Identities
@@ -390,7 +388,10 @@ impl AuthServer {
 
         // Success, build the response
         return Ok(X509Authorization {
-            authority: auth_props.authority.clone(),
+            authority: response
+                .get("authority")
+                .ok_or(AuthorizationError::AuthorizerError)?
+                .to_string(),
             issuer: response
                 .get("issuer")
                 .unwrap_or(&"Rustica".to_owned())

rustica/src/error.rs

@@ -12,6 +12,10 @@ pub enum RusticaServerError {
     BadCertOptions = 5,
     NotAuthorized = 6,
     BadRequest = 7,
+    PivClientCertTooBig = 8,
+    PivIntermediateCertTooBig = 9,
+    U2fAttestationTooBig = 10,
+    U2fIntermediateCertTooBig = 11,
     Unknown = 9001,
 }
 
@@ -23,4 +27,4 @@ impl From<AuthorizationError> for RusticaServerError {
             _ => RusticaServerError::Unknown,
         }
     }
-}
+}

rustica/src/verification.rs

@@ -9,12 +9,29 @@ use sshcerts::{
 };
 use std::convert::TryFrom;
 
+// For Yubikey 5 Nano:
+// - PIV intermediate cert size is approx 800 bytes
+// - PIV client cert is approx 700 bytes
+// - U2F intermediate cert is approx 800 bytes
+// - U2F attestation statement is approx 256 bytes
+const CERT_MAX_SIZE: usize = 1024 * 2; // 2 KiB
+
 /// Verify a provided yubikey attestation certification and intermediate
 /// certificate are valid against the Yubico attestation Root CA.
 pub fn verify_piv_certificate_chain(
     client: &[u8],
     intermediate: &[u8],
 ) -> Result<Key, RusticaServerError> {
+    // Restrict the max size of certificates
+    // For Yubikey 5 Nano, actual intermediate cert size is approx 800 bytes
+    if intermediate.len() > CERT_MAX_SIZE {
+        return Err(RusticaServerError::PivIntermediateCertTooBig);
+    }
+    // For Yubikey 5 Nano, actual client cert size is approx 700 bytes
+    if client.len() > CERT_MAX_SIZE {
+        return Err(RusticaServerError::PivClientCertTooBig);
+    }
+
     // Extract the certificate public key and convert to an sshcerts PublicKey
     let validated_piv_data = verify_certificate_chain(client, intermediate, None)
         .map_err(|_| RusticaServerError::InvalidKey)?;
@@ -47,6 +64,16 @@ pub fn verify_u2f_certificate_chain(
     application: &[u8],
     u2f_challenge_hashed: bool,
 ) -> Result<Key, RusticaServerError> {
+    // Restrict the max size for the attestation data and intermediate certificate
+    // For Yubikey 5 Nano, actual intermediate cert size is approx 800 bytes
+    if intermediate.len() > CERT_MAX_SIZE {
+        return Err(RusticaServerError::U2fIntermediateCertTooBig);
+    }
+    // For Yubikey 5 Nano, actual auth_data size is approx 256 bytes
+    if auth_data.len() > CERT_MAX_SIZE {
+        return Err(RusticaServerError::U2fAttestationTooBig);
+    }
+
     // Take all the provided data and validate it up to the Yubico U2F Root CA
 
     let challenge = if u2f_challenge_hashed {

tests/test_configs/rustica_local_file_alt.toml

@@ -94,7 +94,7 @@ ECAwQ=
 '''
 
 x509_private_key = "MIG2AgEAMBAGByqGSM49AgEGBSuBBAAiBIGeMIGbAgEBBDDOLp3ZkQZasW1BKZ+fG3ODQgNThvI7pV38DOEFCz6c+gr8whSiV6EHWT04VrddShehZANiAARKbU0hcFy5+9qqHxGx/FBQb2dh6u+pAYh4ASh7skBkPv5DK/46FH6pvyPp6Gfkp8gagcFsr9nAKbwjkVTtBopuhh45KUM5k4VqIqaNox7g+XCrgG29oVqA5WZpW8DFH2c="
-x509_private_key_alg = "p384"
+x509_private_key_algorithm = "p384"
 
 client_certificate_authority_private_key = "MIG2AgEAMBAGByqGSM49AgEGBSuBBAAiBIGeMIGbAgEBBDDOLp3ZkQZasW1BKZ+fG3ODQgNThvI7pV38DOEFCz6c+gr8whSiV6EHWT04VrddShehZANiAARKbU0hcFy5+9qqHxGx/FBQb2dh6u+pAYh4ASh7skBkPv5DK/46FH6pvyPp6Gfkp8gagcFsr9nAKbwjkVTtBopuhh45KUM5k4VqIqaNox7g+XCrgG29oVqA5WZpW8DFH2c="
 client_certificate_authority_private_key_algorithm = "p384"
@@ -103,4 +103,4 @@ client_certificate_authority_common_name = "RusticaAccess"
 [logging."stdout"]
 
 [authorization."database"]
-path = "examples/example.db"
+path = "examples/example.db"