[fix] CFI check for TRNG source

This fix addresses issue# #920
chipsalliance · Oct 12, 2023 · b3db033 · b3db033
1 parent 203e80c
commit b3db033
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Showing 2 changed files with 12 additions and 2 deletions.
diff --git a/drivers/src/soc_ifc.rs b/drivers/src/soc_ifc.rs
@@ -144,6 +144,10 @@ impl SocIfc {
         ((val >> 31) & 1) != 0
     }
 
+    pub fn hw_config_internal_trng(&mut self) -> bool {
+        self.soc_ifc.regs().cptra_hw_config().read().i_trng_en()
+    }
+
     /// Enable or disable WDT1
     ///
     /// # Arguments

diff --git a/rom/dev/src/main.rs b/rom/dev/src/main.rs
@@ -16,13 +16,13 @@ Abstract:
 #![cfg_attr(feature = "fake-rom", allow(unused_imports))]
 
 use crate::{lock::lock_registers, print::HexBytes};
-use caliptra_cfi_lib::CfiCounter;
+use caliptra_cfi_lib::{cfi_assert, cfi_assert_eq, CfiCounter};
 use caliptra_registers::soc_ifc::SocIfcReg;
 use core::hint::black_box;
 
 use caliptra_drivers::{
     cprintln, report_fw_error_fatal, report_fw_error_non_fatal, CaliptraError, Ecc384, Hmac384,
-    KeyVault, Mailbox, ResetReason, Sha256, Sha384, Sha384Acc, ShaAccLockState, SocIfc,
+    KeyVault, Mailbox, ResetReason, Sha256, Sha384, Sha384Acc, ShaAccLockState, SocIfc, Trng,
 };
 use caliptra_error::CaliptraResult;
 use caliptra_image_types::RomInfo;
@@ -74,6 +74,12 @@ pub extern "C" fn rom_entry() -> ! {
         cprintln!("[state] CFI Disabled");
     }
 
+    // Check if TRNG is correctly sourced as per hw config.
+    match env.trng {
+        Trng::Internal(_) => cfi_assert!(env.soc_ifc.hw_config_internal_trng()),
+        Trng::External(_) => cfi_assert!(!env.soc_ifc.hw_config_internal_trng()),
+    }
+
     let _lifecyle = match env.soc_ifc.lifecycle() {
         caliptra_drivers::Lifecycle::Unprovisioned => "Unprovisioned",
         caliptra_drivers::Lifecycle::Manufacturing => "Manufacturing",