tcti: Adds support for libtpms backend

This is useful for running tests without having to spawn a simulator in
another process.

Signed-off-by: Arthur Gautier <arthur.gautier@arista.com>

tss-esapi/src/context.rs

@@ -3,7 +3,7 @@
 mod handle_manager;
 use crate::{
     attributes::SessionAttributesBuilder,
-    constants::{CapabilityType, PropertyTag, SessionType},
+    constants::{CapabilityType, PropertyTag, SessionType, StartupType},
     handles::{ObjectHandle, SessionHandle},
     interface_types::{algorithm::HashingAlgorithm, session_handles::AuthSession},
     structures::{CapabilityData, SymmetricDefinition},
@@ -91,7 +91,7 @@ impl Context {
     pub fn new(tcti_name_conf: TctiNameConf) -> Result<Self> {
         let mut esys_context = null_mut();
 
-        let mut _tcti_context = TctiContext::initialize(tcti_name_conf)?;
+        let mut _tcti_context = TctiContext::initialize(tcti_name_conf.clone())?;
 
         ReturnCode::ensure_success(
             unsafe {
@@ -107,13 +107,19 @@ impl Context {
         )?;
 
         let esys_context = unsafe { Some(Malloced::from_raw(esys_context)) };
-        Ok(Context {
+        let mut context = Context {
             esys_context,
             sessions: (None, None, None),
             _tcti_context,
             handle_manager: HandleManager::new(),
             cached_tpm_properties: HashMap::new(),
-        })
+        };
+
+        if matches!(tcti_name_conf, TctiNameConf::LibTpms { .. }) {
+            context.startup(StartupType::Clear)?;
+        }
+
+        Ok(context)
     }
 
     /// Create a new ESYS context based on the TAB Resource Manager Daemon.

tss-esapi/src/tcti_ldr.rs

@@ -21,6 +21,7 @@ const DEVICE: &str = "device";
 const MSSIM: &str = "mssim";
 const SWTPM: &str = "swtpm";
 const TABRMD: &str = "tabrmd";
+const LIBTPMS: &str = "libtpms";
 
 /// TCTI Context created via a TCTI Loader Library.
 /// Wrapper around the TSS2_TCTI_CONTEXT structure.
@@ -139,6 +140,10 @@ pub enum TctiNameConf {
     ///
     /// For more information about configuration, see [this page](https://www.mankier.com/3/Tss2_Tcti_Mssim_Init)
     Swtpm(TpmSimulatorConfig),
+    /// Connect to a TPM (simulator) available as a library
+    ///
+    /// This allows for an optional state file
+    LibTpms { state: Option<PathBuf> },
     /// Connect to a TPM through an Access Broker/Resource Manager daemon
     ///
     /// For more information about configuration, see [this page](https://www.mankier.com/3/Tss2_Tcti_Tabrmd_Init)
@@ -174,6 +179,7 @@ impl TryFrom<TctiNameConf> for CString {
             TctiNameConf::Mssim(..) => MSSIM,
             TctiNameConf::Swtpm(..) => SWTPM,
             TctiNameConf::Tabrmd(..) => TABRMD,
+            TctiNameConf::LibTpms { .. } => LIBTPMS,
         };
 
         let tcti_conf = match tcti {
@@ -204,6 +210,9 @@ impl TryFrom<TctiNameConf> for CString {
             TctiNameConf::Tabrmd(config) => {
                 format!("bus_name={},bus_type={}", config.bus_name, config.bus_type)
             }
+            TctiNameConf::LibTpms { state } => state
+                .and_then(|s| s.to_str().map(str::to_string))
+                .unwrap_or_default(),
         };
 
         if tcti_conf.is_empty() {
@@ -247,6 +256,16 @@ impl FromStr for TctiNameConf {
             )?));
         }
 
+        let libtpms_pattern = Regex::new(r"^libtpms(:(.*))?$").unwrap(); //should not fail
+        if let Some(captures) = libtpms_pattern.captures(config_str) {
+            return Ok(TctiNameConf::LibTpms {
+                state: captures
+                    .get(2)
+                    .map(|m| m.as_str())
+                    .and_then(|s| PathBuf::from_str(s).ok()),
+            });
+        }
+
         Err(Error::WrapperError(WrapperErrorKind::InvalidParam))
     }
 }