feat: configuration for attestation

Signed-off-by: Richard Zak <[email protected]>

Cargo.toml

@@ -30,6 +30,7 @@ anyhow = { version = "^1.0.66", default-features = false }
 base64 = { version = "^0.13.1", default-features = false }
 mime = { version = "^0.3.16", default-features = false }
 confargs = { version = "^0.1.3", default-features = false }
+serde = { version = "1.0", features = ["derive"] }
 
 [target.'cfg(not(target_os = "wasi"))'.dependencies]
 tokio = { version = "^1.21.2", features = ["rt-multi-thread", "macros"], default-features = false }
@@ -41,6 +42,7 @@ http = { version = "^0.2.6", default-features = false }
 memoffset = { version = "0.7.1", default-features = false }
 rstest = { version = "0.15", default-features = false }
 testaso = { version = "0.1", default-features = false }
+toml = "0.5"
 
 [profile.release]
 incremental = false

crates/sgx_validation/Cargo.toml

@@ -9,7 +9,10 @@ description = "Intel SGX Attestation validation library for Steward"
 cryptography = { path = "../cryptography" }
 anyhow = { version = "^1.0.55", default-features = false }
 der = { version = "0.6", features = ["std"], default-features = false }
+hex = "0.4"
+serde = { version = "1.0", features = ["derive", "std"] }
 sgx = { version = "0.5.0", default-features = false }
 
 [dev-dependencies]
 testaso = { version = "0.1", default-features = false }
+toml = "0.5"

crates/sgx_validation/src/config.rs

@@ -0,0 +1,124 @@
+// SPDX-FileCopyrightText: 2022 Profian Inc. <[email protected]>
+// SPDX-License-Identifier: AGPL-3.0-only
+
+use serde::de::Error;
+use serde::{Deserialize, Deserializer, Serialize};
+use sgx::parameters::Features;
+
+#[derive(Clone, Deserialize, Debug, Default, Serialize)]
+#[serde(deny_unknown_fields)]
+pub struct Config {
+    /// Values for `mrsigner` in the report body.
+    /// This is the list of public keys which have signed the Enarx binary.
+    #[serde(default)]
+    #[serde(deserialize_with = "from_hex")]
+    pub enarx_signer: Option<Vec<Vec<u8>>>,
+
+    /// Values for `features`.
+    #[serde(default)]
+    #[serde(deserialize_with = "from_features")]
+    pub features: Option<u64>,
+
+    /// Value allowed for `cpusvn`.
+    pub cpu_svn: Option<Vec<u8>>,
+
+    /// Value for `isv_svn`, do not allow versions below this.
+    pub enclave_security_version: Option<u16>,
+
+    /// Value for `isv_prodid`, do not allow versions below this.
+    pub enclave_product_id: Option<u16>,
+}
+
+fn from_hex<'de, D>(deserializer: D) -> Result<Option<Vec<Vec<u8>>>, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    let s: Vec<&str> = Deserialize::deserialize(deserializer)?;
+
+    let mut outer_vec = Vec::new();
+    for hash_string in s {
+        outer_vec.push(hex::decode(hash_string).map_err(|_| Error::custom("invalid hex"))?);
+    }
+
+    Ok(Some(outer_vec))
+}
+
+fn from_features<'de, D>(deserializer: D) -> Result<Option<u64>, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    let s: &str = Deserialize::deserialize(deserializer)?;
+
+    let mut flags = Features::empty();
+
+    flags |= Features::INIT; // Must be set
+    flags |= Features::MODE64BIT; // Isn't everything 64-bit?
+
+    for flag in s.to_string().split('|') {
+        match flag.trim() {
+            "CET" => {
+                flags |= Features::CET;
+            }
+            "Debug" => {
+                flags |= Features::DEBUG;
+            }
+            "Eint_Key" => {
+                flags |= Features::EINIT_KEY;
+            }
+            "KSS" => {
+                flags |= Features::KSS;
+            }
+            "Provisioning_Key" => {
+                flags |= Features::PROVISIONING_KEY;
+            }
+            _ => return Err(D::Error::custom(format!("unknown flag '{}'", flag))),
+        }
+    }
+
+    Ok(Some(flags.bits()))
+}
+
+impl Config {
+    pub fn features(&self) -> Features {
+        match self.features {
+            Some(f) => Features::from_bits_truncate(f),
+            None => Features::empty(),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::config::Config;
+
+    #[test]
+    fn test_empty_config() {
+        let config_raw = r#"
+        "#;
+
+        let config_obj: Config = toml::from_str(config_raw).expect("Couldn't deserialize");
+        assert!(config_obj.enarx_signer.is_none());
+        assert!(config_obj.enclave_security_version.is_none());
+        assert!(config_obj.cpu_svn.is_none());
+    }
+
+    #[test]
+    fn test_list_of_hashes() {
+        let config_raw = r#"
+        enarx_signer = ["1234567890", "00112233445566778899"]
+        "#;
+
+        let config_obj: Config = toml::from_str(config_raw).expect("Couldn't deserialize");
+        assert!(config_obj.enarx_signer.is_some());
+        assert_eq!(config_obj.enarx_signer.clone().unwrap().len(), 2);
+        assert_eq!(
+            config_obj.enarx_signer.clone().unwrap().first().unwrap(),
+            &hex::decode("1234567890").unwrap()
+        );
+        assert_eq!(
+            config_obj.enarx_signer.unwrap().get(1).unwrap(),
+            &hex::decode("00112233445566778899").unwrap()
+        );
+        assert!(config_obj.cpu_svn.is_none());
+    }
+}

crates/sgx_validation/src/lib.rs

@@ -1,19 +1,21 @@
 // SPDX-FileCopyrightText: 2022 Profian Inc. <[email protected]>
 // SPDX-License-Identifier: AGPL-3.0-only
 
-mod quote;
+pub mod config;
+pub mod quote;
 
 use cryptography::ext::*;
 use quote::traits::ParseBytes;
 
 use std::fmt::Debug;
 
+use crate::config::Config;
 use anyhow::{anyhow, Result};
 use cryptography::const_oid::ObjectIdentifier;
 use cryptography::sha2::{Digest, Sha256};
 use cryptography::x509::{ext::Extension, request::CertReqInfo, Certificate, TbsCertificate};
 use der::{Decode, Encode};
-use sgx::parameters::{Attributes, MiscSelect};
+use sgx::parameters::MiscSelect;
 
 #[derive(Clone, Debug)]
 pub struct Sgx([Certificate<'static>; 1]);
@@ -29,7 +31,7 @@ impl Sgx {
     pub const OID: ObjectIdentifier = ObjectIdentifier::new_unwrap("1.3.6.1.4.1.58270.1.2");
     pub const ATT: bool = true;
 
-    fn trusted<'c>(&'c self, chain: &'c [Certificate<'c>]) -> Result<&'c TbsCertificate<'c>> {
+    pub fn trusted<'c>(&'c self, chain: &'c [Certificate<'c>]) -> Result<&'c TbsCertificate<'c>> {
         let mut signer = &self.0[0].tbs_certificate;
         for cert in self.0.iter().chain(chain.iter()) {
             signer = signer.verify_crt(cert)?;
@@ -38,7 +40,13 @@ impl Sgx {
         Ok(signer)
     }
 
-    pub fn verify(&self, cri: &CertReqInfo<'_>, ext: &Extension<'_>, dbg: bool) -> Result<bool> {
+    pub fn verify(
+        &self,
+        cri: &CertReqInfo<'_>,
+        ext: &Extension<'_>,
+        config: Option<&Config>,
+        dbg: bool,
+    ) -> Result<bool> {
         if ext.critical {
             return Err(anyhow!("sgx extension cannot be critical"));
         }
@@ -80,38 +88,59 @@ impl Sgx {
 
         if !dbg {
             // TODO: Validate that the certification request came from an SGX enclave.
-            let hash = Sha256::digest(&cri.public_key.to_vec()?);
+            let hash = Sha256::digest(cri.public_key.to_vec()?);
             if hash.as_slice() != &rpt.reportdata[..hash.as_slice().len()] {
                 return Err(anyhow!("sgx report data is invalid"));
             }
 
-            if rpt.mrenclave != [0u8; 32] {
-                return Err(anyhow!("untrusted enarx runtime"));
-            }
-
-            if rpt.mrsigner != [0u8; 32] {
-                return Err(anyhow!("untrusted enarx signer"));
-            }
-
-            if rpt.cpusvn != [0u8; 16] {
-                return Err(anyhow!("untrusted cpu"));
-            }
-
-            if rpt.attributes() != Attributes::default() {
-                return Err(anyhow!("untrusted attributes"));
+            if config.is_some() {
+                let config_ref = config.as_ref().unwrap();
+                if config_ref.enarx_signer.is_some() {
+                    let mut signed = false;
+                    for signer in config_ref.enarx_signer.as_ref().unwrap() {
+                        if rpt.mrsigner == signer.as_slice() {
+                            signed = true;
+                            break;
+                        }
+                    }
+                    if !signed {
+                        return Err(anyhow!("untrusted enarx signer"));
+                    }
+                }
+
+                if config_ref.cpu_svn.is_some() {
+                    let conf_version = config_ref.cpu_svn.as_ref().unwrap();
+                    for index in 0..rpt.cpusvn.len() {
+                        if rpt.cpusvn.get(index).unwrap() < conf_version.get(index).unwrap() {
+                            return Err(anyhow!("untrusted cpu"));
+                        }
+                    }
+                }
+
+                if config_ref.enclave_product_id.is_some()
+                    && rpt.enclave_product_id() != config_ref.enclave_product_id.unwrap()
+                {
+                    return Err(anyhow!("untrusted enclave product id"));
+                }
+
+                if config_ref.enclave_security_version.is_some()
+                    && rpt.enclave_security_version() < config_ref.enclave_security_version.unwrap()
+                {
+                    return Err(anyhow!("untrusted enclave"));
+                }
+
+                if rpt
+                    .attributes()
+                    .features()
+                    .intersects(config_ref.features())
+                {
+                    return Err(anyhow!("untrusted features"));
+                }
             }
 
             if rpt.misc_select() != MiscSelect::default() {
                 return Err(anyhow!("untrusted misc select"));
             }
-
-            if rpt.enclave_product_id() != u16::MAX {
-                return Err(anyhow!("untrusted enclave product id"));
-            }
-
-            if rpt.enclave_security_version() < u16::MAX {
-                return Err(anyhow!("untrusted enclave"));
-            }
         }
 
         Ok(false)