AA: Update CcaAttester to use TSM Report ABI

Signed-off-by: Mathias Brossard <[email protected]>

Makefile

@@ -50,8 +50,10 @@ else ifeq ($(TEE_PLATFORM), amd)
   else
     RESOURCE_PROVIDER = sev,kbs
   endif
+else ifeq ($(TEE_PLATFORM), cca)
+  ATTESTER = cca-attester
 endif
-# TODO: Add support for CCA and CSV
+# TODO: Add support for CSV
 
 ifeq ($(ARCH), $(filter $(ARCH), s390x powerpc64le))
   $(info s390x/powerpc64le only supports gnu)

attestation-agent/attestation-agent/Cargo.toml

@@ -58,13 +58,14 @@ kbs = ["kbs_protocol/background_check", "token"]
 # CoCoAS Attestation Token
 coco_as = ["reqwest", "token"]
 
-all-attesters = ["tdx-attester", "sgx-attester", "az-snp-vtpm-attester", "az-tdx-vtpm-attester", "snp-attester", "se-attester"]
+all-attesters = ["tdx-attester", "sgx-attester", "az-snp-vtpm-attester", "az-tdx-vtpm-attester", "snp-attester", "se-attester", "cca-attester"]
 tdx-attester = ["kbs_protocol?/tdx-attester", "attester/tdx-attester"]
 sgx-attester = ["kbs_protocol?/sgx-attester", "attester/sgx-attester"]
 az-snp-vtpm-attester = ["kbs_protocol?/az-snp-vtpm-attester", "attester/az-snp-vtpm-attester"]
 az-tdx-vtpm-attester = ["kbs_protocol?/az-tdx-vtpm-attester", "attester/az-tdx-vtpm-attester"]
 snp-attester = ["kbs_protocol?/snp-attester", "attester/snp-attester"]
 se-attester = ["kbs_protocol?/se-attester", "attester/se-attester"]
+cca-attester = ["kbs_protocol?/cca-attester", "attester/cca-attester"]
 
 # Either `rust-crypto` or `openssl` should be enabled to work as underlying crypto module
 rust-crypto = ["kbs_protocol?/rust-crypto"]

attestation-agent/attester/Cargo.toml

@@ -15,7 +15,6 @@ clap = { workspace = true, features = ["derive"], optional = true }
 hex.workspace = true
 kbs-types.workspace = true
 log.workspace = true
-nix = { workspace = true, optional = true, features = ["ioctl", "fs"] }
 occlum_dcap = { git = "https://github.com/occlum/occlum", tag = "v0.29.7", optional = true }
 pv = { version = "0.10.0", package = "s390_pv", optional = true }
 scroll = { version = "0.12.0", default-features = false, features = ["derive", "std"], optional = true }
@@ -68,7 +67,7 @@ az-snp-vtpm-attester = ["az-snp-vtpm"]
 az-tdx-vtpm-attester = ["az-tdx-vtpm"]
 snp-attester = ["sev"]
 csv-attester = ["csv-rs", "codicon", "hyper", "hyper-tls", "tokio"]
-cca-attester = ["nix"]
+cca-attester = ["tsm-report"]
 se-attester  = ["pv"]
 
 bin = ["tokio/rt", "tokio/macros", "clap"]

attestation-agent/attester/src/cca/mod.rs

@@ -1,105 +1,56 @@
-// Copyright (c) 2023 Arm Ltd.
+// Copyright (c) 2023-2024 Arm Ltd.
 //
 // SPDX-License-Identifier: Apache-2.0
 //
 
+use super::tsm_report::*;
 use super::Attester;
 use anyhow::*;
-use base64::Engine;
-use nix::fcntl::{open, OFlag};
-use nix::sys::stat::Mode;
-use nix::unistd::close;
 use serde::{Deserialize, Serialize};
-use std::path::Path;
 
-const CCA_DEVICE_PATH: &str = "/dev/cca_attestation";
+const CCA_CHALLENGE_SIZE: usize = 64;
 
-// NOTE: The path might be different when the CCA feature is public available, will come back to update the actual path if needed.
 pub fn detect_platform() -> bool {
-    Path::new(CCA_DEVICE_PATH).exists()
+    #[cfg(target_arch = "aarch64")]
+    return TsmReportPath::new(TsmReportProvider::Cca).is_ok();
+    #[cfg(not(target_arch = "aarch64"))]
+    return false;
 }
 
 #[derive(Debug, Default)]
-pub struct CCAAttester {}
+pub struct CcaAttester {}
 
 #[derive(Serialize, Deserialize)]
 struct CcaEvidence {
     /// CCA token
     token: Vec<u8>,
 }
 
-#[allow(non_camel_case_types)]
-#[repr(C)]
-pub struct cca_ioctl_request {
-    challenge: [u8; 64],
-    token: [u8; 4096],
-    token_length: u64,
-}
-
-nix::ioctl_readwrite!(cca_attestation_request, b'A', 1, cca_ioctl_request);
-
 #[async_trait::async_trait]
-impl Attester for CCAAttester {
+impl Attester for CcaAttester {
     async fn get_evidence(&self, mut challenge: Vec<u8>) -> Result<String> {
-        challenge.resize(64, 0);
-        let token = attestation(challenge)?;
+        if challenge.len() > CCA_CHALLENGE_SIZE {
+            bail!("CCA Attester: Challenge size must be {CCA_CHALLENGE_SIZE} or less.");
+        }
+
+        challenge.resize(CCA_CHALLENGE_SIZE, 0);
+        let tsm = TsmReportPath::new(TsmReportProvider::Cca)?;
+        let token = tsm.attestation_report(TsmReportData::Cca(challenge))?;
         let evidence = CcaEvidence { token };
-        let ev = serde_json::to_string(&evidence).context("Serialize CCA evidence failed")?;
+        let ev =
+            serde_json::to_string(&evidence).context("Serialization of CCA evidence failed")?;
         Ok(ev)
     }
 }
 
-fn attestation(challenge: Vec<u8>) -> Result<Vec<u8>, Error> {
-    log::info!("cca_test::attestation started");
-
-    let challenge = challenge.as_slice().try_into()?;
-
-    match open(CCA_DEVICE_PATH, OFlag::empty(), Mode::empty()) {
-        Result::Ok(f) => {
-            log::info!("cca_test::attestation opening attestation succeeded");
-            let mut request = cca_ioctl_request {
-                challenge,
-                token: [0u8; 4096],
-                token_length: 0u64,
-            };
-
-            // this is unsafe code block since ioctl call `cca_attestation_request` has the unsafe signature.
-            match unsafe { cca_attestation_request(f, &mut request) } {
-                Result::Ok(c) => {
-                    log::info!("cca_test::attestation ioctl call succeeded ({})", c);
-                    log::info!(
-                        "cca_test::attestation token is {} bytes long",
-                        request.token_length
-                    );
-                    let base64 = base64::engine::general_purpose::STANDARD
-                        .encode(&request.token[0..(request.token_length as usize)]);
-                    log::info!("cca_test::attestation token = {:x?}", base64);
-                    let token = request.token[0..(request.token_length as usize)].to_vec();
-                    close(f)?;
-                    Ok(token)
-                }
-                Err(e) => {
-                    log::error!("cca_test::attestation ioctl failed! {}", e);
-                    close(f)?;
-                    bail!(e)
-                }
-            }
-        }
-        Err(err) => {
-            log::error!("cca_test::attestation opening attestation failed! {}", err);
-            bail!(err)
-        }
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
 
     #[ignore]
     #[tokio::test]
     async fn test_cca_get_evidence() {
-        let attester = CCAAttester::default();
+        let attester = CcaAttester::default();
         let report_data: Vec<u8> = vec![0; 48];
         let evidence = attester.get_evidence(report_data).await;
         assert!(evidence.is_ok());

attestation-agent/attester/src/lib.rs

@@ -53,7 +53,7 @@ impl TryFrom<Tee> for BoxedAttester {
             #[cfg(feature = "az-tdx-vtpm-attester")]
             Tee::AzTdxVtpm => Box::<az_tdx_vtpm::AzTdxVtpmAttester>::default(),
             #[cfg(feature = "cca-attester")]
-            Tee::Cca => Box::<cca::CCAAttester>::default(),
+            Tee::Cca => Box::<cca::CcaAttester>::default(),
             #[cfg(feature = "snp-attester")]
             Tee::Snp => Box::<snp::SnpAttester>::default(),
             #[cfg(feature = "csv-attester")]

attestation-agent/attester/src/tsm_report/mod.rs

@@ -33,13 +33,16 @@ pub enum TsmReportError {
 
 #[derive(PartialEq, Debug, EnumString)]
 pub enum TsmReportProvider {
+    #[strum(serialize = "arm_cca_guest\n")]
+    Cca,
     #[strum(serialize = "tdx_guest\n")]
     Tdx,
     #[strum(serialize = "sev_guest\n")]
     Sev,
 }
 
 pub enum TsmReportData {
+    Cca(Vec<u8>),
     Tdx(Vec<u8>),
     Sev(u8, Vec<u8>),
 }
@@ -86,6 +89,7 @@ impl TsmReportPath {
         let report_path = self.path.as_path();
 
         let report_data = match provider_data {
+            TsmReportData::Cca(inblob) => inblob,
             TsmReportData::Tdx(inblob) => inblob,
             TsmReportData::Sev(privlevel, inblob) => {
                 // TODO: untested