Merge pull request #782 from Dstack-TEE/feat/tsm-provider-env-support

feat(attest): TSM provider detection and path overrides

Author: kvinwang

dstack/Cargo.lock

@@ -7,9 +7,11 @@
 use crate::{codecs::VecOf, tdx::TdxEvent};
 use anyhow::{Context, Result};
 use scale::Decode;
+use std::path::PathBuf;
 
 /// The path to boottime ccel file.
 const CCEL_FILE: &str = "/sys/firmware/acpi/tables/data/CCEL";
+const CCEL_FILE_ENV: &str = "DSTACK_CCEL_FILE";
 
 pub const TPM_ALG_ERROR: u16 = 0x0;
 pub const TPM_ALG_RSA: u16 = 0x1;
@@ -300,8 +302,12 @@ impl TcgEventLog {
     }
 
     pub fn decode_from_ccel_file() -> Result<Self> {
-        let data = fs_err::read(CCEL_FILE).context("Failed to read CCEL")?;
-        Self::decode(&mut data.as_slice())
+        let path = std::env::var_os(CCEL_FILE_ENV)
+            .map(PathBuf::from)
+            .unwrap_or_else(|| PathBuf::from(CCEL_FILE));
+        let data = fs_err::read(&path)
+            .with_context(|| format!("failed to read CCEL from {}", path.display()))?;
+        Self::decode(&mut data.as_slice()).context("failed to decode CCEL")
     }
 
     pub fn to_cc_event_log(&self) -> Result<Vec<TdxEvent>> {

dstack/cc-eventlog/src/tcg.rs

@@ -129,6 +129,14 @@ pub fn label_tdx_acpi_data_events(event_logs: &mut [TdxEvent]) {
     }
 }
 
+/// Decode a raw CCEL byte stream into dstack's TDX event representation.
+pub fn decode_ccel(data: &[u8]) -> Result<Vec<TdxEvent>> {
+    let mut input = data;
+    let mut event_logs = TcgEventLog::decode(&mut input)?.to_cc_event_log()?;
+    label_tdx_acpi_data_events(&mut event_logs);
+    Ok(event_logs)
+}
+
 /// Read both boottime and runtime event logs.
 pub fn read_event_log() -> Result<Vec<TdxEvent>> {
     let mut event_logs = TcgEventLog::decode_from_ccel_file()?.to_cc_event_log()?;
@@ -172,4 +180,12 @@ mod tests {
         assert_eq!(events[0].event, "");
         assert_eq!(events[4].event, "app-id");
     }
+
+    #[test]
+    fn decodes_the_bundled_ccel() {
+        let events = decode_ccel(include_bytes!("../samples/ccel.bin")).unwrap();
+        assert!(!events.is_empty());
+        assert!(events.iter().all(|event| event.imr <= 3));
+        assert!(events.iter().all(|event| event.digest().len() == 48));
+    }
 }

dstack/cc-eventlog/src/tdx.rs

@@ -280,7 +280,7 @@ fn choose_dstack_attestation_mode(has_tdx: bool, has_sev_snp: bool) -> Result<At
 impl AttestationMode {
     /// Detect attestation mode from system
     pub fn detect() -> Result<Self> {
-        let has_tdx = std::path::Path::new("/dev/tdx_guest").exists();
+        let has_tdx = tdx_attest::is_tdx_available();
         let has_sev_snp =
             std::path::Path::new("/dev/sev-guest").exists() || has_sev_snp_tsm_provider();
 

dstack/dstack-attest/src/attestation.rs

@@ -32,3 +32,4 @@ insta.workspace = true
 serde_json.workspace = true
 dcap-qvl.workspace = true
 tokio = { workspace = true, features = ["rt-multi-thread", "macros"] }
+tempfile.workspace = true

dstack/tdx-attest/Cargo.toml

@@ -49,3 +49,7 @@ pub fn get_report(_report_data: &TdxReportData) -> Result<TdxReport> {
 pub fn extend_rtmr(_index: u32, _event_type: u32, _digest: [u8; 48]) -> Result<()> {
     Err(TdxAttestError::NotSupported)
 }
+
+pub fn is_tdx_available() -> bool {
+    false
+}

dstack/tdx-attest/src/dummy.rs

@@ -33,6 +33,7 @@ const CONFIGFS_BASE: &str = "/sys/kernel/config/tsm/report";
 const CONFIGFS_DEFAULT: &str = "/sys/kernel/config/tsm/report/com.intel.dcap";
 const CONFIGFS_PATH_ENV: &str = "DCAP_TDX_QUOTE_CONFIGFS_PATH";
 const RTMR_SYSFS_BASE: &str = "/sys/devices/virtual/misc/tdx_guest/measurements";
+const RTMR_SYSFS_PATH_ENV: &str = "DCAP_TDX_RTMR_SYSFS_PATH";
 const TDX_ATTEST_CONFIG_PATH: &str = "/etc/tdx-attest.conf";
 
 const TDX_REPORT_DATA_SIZE: usize = 64;
@@ -166,7 +167,7 @@ static CONFIGFS_MKDIR_TRIED: Mutex<bool> = Mutex::new(false);
 pub fn get_quote(report_data: &TdxReportData) -> Result<Vec<u8>> {
     let _guard = TDX_LOCK.lock().map_err(|_| TdxAttestError::Busy)?;
 
-    if is_configfs_available() {
+    if should_try_configfs() {
         return get_quote_via_configfs(report_data);
     }
 
@@ -179,8 +180,35 @@ pub fn get_quote(report_data: &TdxReportData) -> Result<Vec<u8>> {
     ))
 }
 
-fn is_configfs_available() -> bool {
-    Path::new(CONFIGFS_DEFAULT).is_dir() || Path::new(CONFIGFS_BASE).is_dir()
+fn should_try_configfs() -> bool {
+    // An explicit override is authoritative. Let prepare_configfs() report an
+    // invalid path instead of silently falling back to another quote method.
+    std::env::var_os(CONFIGFS_PATH_ENV).is_some()
+        || Path::new(CONFIGFS_DEFAULT).is_dir()
+        || Path::new(CONFIGFS_BASE).is_dir()
+}
+
+/// Return whether a TDX guest provider is available through either the legacy
+/// misc device or the standard TSM report interface.
+pub fn is_tdx_available() -> bool {
+    if Path::new(TDX_GUEST_DEVICE).exists() {
+        return true;
+    }
+
+    if let Some(path) = std::env::var_os(CONFIGFS_PATH_ENV) {
+        return verify_configfs_provider(Path::new(&path)).unwrap_or(false);
+    }
+
+    if verify_configfs_provider(Path::new(CONFIGFS_DEFAULT)).unwrap_or(false) {
+        return true;
+    }
+
+    fs::read_dir(CONFIGFS_BASE)
+        .ok()
+        .into_iter()
+        .flatten()
+        .filter_map(std::result::Result::ok)
+        .any(|entry| verify_configfs_provider(&entry.path()).unwrap_or(false))
 }
 
 fn is_vsock_available() -> bool {
@@ -223,8 +251,8 @@ pub fn extend_rtmr(index: u32, _event_type: u32, digest: [u8; 48]) -> Result<()>
         return Err(TdxAttestError::InvalidRtmrIndex(index));
     }
 
-    if is_rtmr_sysfs_available() {
-        return extend_rtmr_via_sysfs(index, &digest);
+    if let Some(base) = rtmr_sysfs_base()? {
+        return extend_rtmr_via_sysfs(&base, index, &digest);
     }
 
     if Path::new(TDX_GUEST_DEVICE).exists() {
@@ -236,24 +264,37 @@ pub fn extend_rtmr(index: u32, _event_type: u32, digest: [u8; 48]) -> Result<()>
     ))
 }
 
-fn is_rtmr_sysfs_available() -> bool {
-    Path::new(RTMR_SYSFS_BASE).is_dir()
+fn rtmr_sysfs_base() -> Result<Option<std::path::PathBuf>> {
+    if let Some(path) = std::env::var_os(RTMR_SYSFS_PATH_ENV) {
+        let path = std::path::PathBuf::from(path);
+        if path.as_os_str().len() < 240 && path.is_dir() {
+            return Ok(Some(path));
+        }
+        return Err(TdxAttestError::NotSupported(format!(
+            "invalid RTMR sysfs path from {RTMR_SYSFS_PATH_ENV}: {}",
+            path.display()
+        )));
+    }
+
+    Ok(Path::new(RTMR_SYSFS_BASE)
+        .is_dir()
+        .then(|| std::path::PathBuf::from(RTMR_SYSFS_BASE)))
 }
 
-fn extend_rtmr_via_sysfs(index: u32, digest: &[u8; 48]) -> Result<()> {
-    let path = format!("{}/rtmr{}:sha384", RTMR_SYSFS_BASE, index);
+fn extend_rtmr_via_sysfs(base: &Path, index: u32, digest: &[u8; 48]) -> Result<()> {
+    let path = base.join(format!("rtmr{index}:sha384"));
 
     let mut file = OpenOptions::new()
         .write(true)
         .open(&path)
-        .map_err(|e| TdxAttestError::ExtendFailure(format!("open {path}: {e}")))?;
+        .map_err(|e| TdxAttestError::ExtendFailure(format!("open {}: {e}", path.display())))?;
 
     file.write_all(digest).map_err(|e| match e.raw_os_error() {
         Some(libc::EINVAL) => TdxAttestError::InvalidRtmrIndex(index),
         Some(libc::EPERM) | Some(libc::EACCES) => {
             TdxAttestError::ExtendFailure(format!("permission denied for RTMR {index}"))
         }
-        _ => TdxAttestError::ExtendFailure(format!("write {path}: {e}")),
+        _ => TdxAttestError::ExtendFailure(format!("write {}: {e}", path.display())),
     })
 }
 
@@ -334,7 +375,10 @@ fn get_quote_via_configfs(report_data: &TdxReportData) -> Result<Vec<u8>> {
 
 fn prepare_configfs() -> Result<String> {
     if let Ok(path) = std::env::var(CONFIGFS_PATH_ENV) {
-        if path.len() < 240 && Path::new(&path).is_dir() && verify_configfs_provider(&path)? {
+        if path.len() < 240
+            && Path::new(&path).is_dir()
+            && verify_configfs_provider(Path::new(&path))?
+        {
             return Ok(path);
         }
         return Err(TdxAttestError::NotSupported(format!(
@@ -343,7 +387,7 @@ fn prepare_configfs() -> Result<String> {
     }
 
     let default_path = CONFIGFS_DEFAULT;
-    if Path::new(default_path).is_dir() && verify_configfs_provider(default_path)? {
+    if Path::new(default_path).is_dir() && verify_configfs_provider(Path::new(default_path))? {
         return Ok(default_path.to_string());
     }
 
@@ -369,7 +413,7 @@ fn prepare_configfs() -> Result<String> {
         let provider_path = format!("{}/provider", default_path);
         for i in 0..5 {
             if Path::new(&provider_path).exists() {
-                if verify_configfs_provider(default_path)? {
+                if verify_configfs_provider(Path::new(default_path))? {
                     return Ok(default_path.to_string());
                 }
                 break;
@@ -383,10 +427,11 @@ fn prepare_configfs() -> Result<String> {
     )))
 }
 
-fn verify_configfs_provider(path: &str) -> Result<bool> {
-    let provider_path = format!("{}/provider", path);
-    let provider = fs::read_to_string(&provider_path)
-        .map_err(|e| TdxAttestError::Unexpected(format!("read {provider_path}: {e}")))?;
+fn verify_configfs_provider(path: &Path) -> Result<bool> {
+    let provider_path = path.join("provider");
+    let provider = fs::read_to_string(&provider_path).map_err(|e| {
+        TdxAttestError::Unexpected(format!("read {}: {e}", provider_path.display()))
+    })?;
 
     Ok(provider.trim().starts_with("tdx_guest"))
 }
@@ -647,3 +692,39 @@ fn parse_qgs_get_quote_response(data: &[u8]) -> Result<Vec<u8>> {
 
     Ok(quote)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn recognizes_tdx_configfs_provider() {
+        let temp = tempfile::tempdir().unwrap();
+        fs::write(temp.path().join("provider"), "tdx_guest_sim\n").unwrap();
+        assert!(verify_configfs_provider(temp.path()).unwrap());
+
+        fs::write(temp.path().join("provider"), "sev_guest\n").unwrap();
+        assert!(!verify_configfs_provider(temp.path()).unwrap());
+    }
+
+    #[test]
+    fn invalid_configfs_override_does_not_fall_back() {
+        let previous = std::env::var_os(CONFIGFS_PATH_ENV);
+        std::env::set_var(
+            CONFIGFS_PATH_ENV,
+            "/definitely/not/a/real/tdx-configfs-provider",
+        );
+
+        let result = get_quote(&[0u8; 64]);
+
+        match previous {
+            Some(value) => std::env::set_var(CONFIGFS_PATH_ENV, value),
+            None => std::env::remove_var(CONFIGFS_PATH_ENV),
+        }
+        assert!(matches!(
+            result,
+            Err(TdxAttestError::NotSupported(message))
+                if message.contains("invalid configfs path from env")
+        ));
+    }
+}

dstack/tdx-attest/src/linux.rs

@@ -99,10 +99,21 @@ log "Syncing system time..."
 # Let the chronyd correct the system time immediately; keep booting if chronyd is not ready yet.
 chronyc makestep || log "Warning: chronyc makestep failed; continuing"
 
-if [[ -e /dev/sev-guest ]] || grep -qw sev_guest /sys/kernel/config/tsm/report/*/provider 2>/dev/null; then
+has_tsm_provider() {
+	local prefix="$1"
+	local provider value
+	for provider in /sys/kernel/config/tsm/report/*/provider; do
+		[[ -r "$provider" ]] || continue
+		value=$(<"$provider")
+		[[ "$value" == "$prefix"* ]] && return 0
+	done
+	return 1
+}
+
+if [[ -e /dev/sev-guest ]] || has_tsm_provider sev_guest; then
 	log "SEV-SNP guest device/TSM provider detected"
-elif [[ -e /dev/tdx_guest ]]; then
-	log "TDX guest device detected"
+elif [[ -e /dev/tdx_guest ]] || has_tsm_provider tdx_guest; then
+	log "TDX guest device/TSM provider detected"
 elif modprobe sev-guest 2>/dev/null; then
 	log "Loaded sev-guest module"
 elif modprobe tdx-guest 2>/dev/null; then