Fix pathLenConstraint for cert chain (#901)

Previously, all pathLenConstraints were set to 0, which will always fail verification. Update pathLenConstraint to `IDevID (5) -> LDevID (4) -> FMC ALias (3) -> RT Alias (2)`. Additionally * Add AuthorityKeyIdentifier to the FMC Alias Key. * Add tests to ensure openssl can verify Caliptra's cert chain. * Autogenerate collateral for fake ROM
chipsalliance · Oct 5, 2023 · 69c4614 · 69c4614
1 parent c9fdb51
commit 69c4614
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Showing 11 changed files with 112 additions and 67 deletions.
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/fmc/src/flow/rt_alias.rs b/fmc/src/flow/rt_alias.rs
@@ -133,6 +133,7 @@ impl RtAliasLayer {
     fn dice_input_from_hand_off(env: &mut FmcEnv) -> CaliptraResult<DiceInput> {
         let auth_pub = HandOff::fmc_pub_key(env);
         let auth_serial_number = X509::subj_sn(env, &auth_pub)?;
+        let auth_key_id = X509::subj_key_id(env, &auth_pub)?;
         // Create initial output
         let input = DiceInput {
             cdi: HandOff::fmc_cdi(env),
@@ -141,7 +142,7 @@ impl RtAliasLayer {
                 pub_key: auth_pub,
             },
             auth_sn: auth_serial_number,
-            auth_key_id: [0u8; 20],
+            auth_key_id,
         };
 
         Ok(input)

diff --git a/rom/dev/Cargo.toml b/rom/dev/Cargo.toml
@@ -24,6 +24,7 @@ zerocopy.workspace = true
 [build-dependencies]
 cfg-if.workspace = true
 hex.workspace = true
+x509-parser.workspace = true
 
 [dev-dependencies]
 caliptra-builder.workspace = true

diff --git a/rom/dev/build.rs b/rom/dev/build.rs
@@ -12,6 +12,8 @@ Abstract:
 
 --*/
 
+use std::env;
+use std::path::{Path, PathBuf};
 use std::process::Command;
 
 fn preprocess(filename: &str, defines: &[(String, String)]) -> Vec<u8> {
@@ -32,11 +34,31 @@ fn preprocess(filename: &str, defines: &[(String, String)]) -> Vec<u8> {
     out.stdout
 }
 
+fn workspace_dir() -> PathBuf {
+    let output = std::process::Command::new(env!("CARGO"))
+        .arg("locate-project")
+        .arg("--workspace")
+        .arg("--message-format=plain")
+        .output()
+        .unwrap()
+        .stdout;
+    let cargo_path = Path::new(std::str::from_utf8(&output).unwrap().trim());
+    cargo_path.parent().unwrap().to_path_buf()
+}
+
+fn be_bytes_to_words(src: &[u8]) -> Vec<u32> {
+    let mut dst = Vec::<u32>::new();
+
+    for i in (0..src.len()).step_by(4) {
+        dst.push(u32::from_be_bytes(src[i..i + 4].try_into().unwrap()));
+    }
+
+    dst
+}
+
 fn main() {
     if cfg!(not(feature = "std")) {
-        use std::env;
         use std::fs;
-        use std::path::PathBuf;
 
         let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap());
         fs::write(out_dir.join("rom.ld"), include_bytes!("src/rom.ld")).unwrap();
@@ -57,4 +79,42 @@ fn main() {
         println!("cargo:rerun-if-changed=src/start.S");
         println!("cargo:rerun-if-changed=build.rs");
     }
+
+    if cfg!(feature = "fake-rom") {
+        use x509_parser::nom::Parser;
+        use x509_parser::prelude::{FromDer, X509CertificateParser};
+        use x509_parser::signature_value::EcdsaSigValue;
+
+        let ws_dir = workspace_dir();
+        let ldev_file =
+            std::fs::read(ws_dir.join("test/tests/smoke_testdata/ldevid_cert.der")).unwrap();
+
+        let mut parser = X509CertificateParser::new();
+        let (_, cert) = parser.parse(&ldev_file).unwrap();
+
+        let tbs = cert.tbs_certificate.as_ref();
+        let (_, sig) = EcdsaSigValue::from_der(cert.signature_value.as_ref()).unwrap();
+
+        // Get words of Signature r and s
+        let mut r = sig.r.as_ref();
+        r = &r[r.len() - 48..];
+        let r_words = be_bytes_to_words(r);
+
+        let mut s = sig.s.as_ref();
+        s = &s[s.len() - 48..];
+        let s_words = be_bytes_to_words(s);
+
+        let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap());
+        std::fs::write(out_dir.join("ldev_tbs.der"), tbs).unwrap();
+        std::fs::write(
+            out_dir.join("ldev_sig_r_words.txt"),
+            format!("{:?}", r_words),
+        )
+        .unwrap();
+        std::fs::write(
+            out_dir.join("ldev_sig_s_words.txt"),
+            format!("{:?}", s_words),
+        )
+        .unwrap();
+    }
 }
diff --git a/rom/dev/src/flow/fake.rs b/rom/dev/src/flow/fake.rs
@@ -40,42 +40,7 @@ use caliptra_image_verify::ImageVerificationEnv;
 use core::ops::Range;
 use fw_processor::FirmwareProcessor;
 
-const FAKE_LDEV_TBS: [u8; 533] = [
-    0x30, 0x82, 0x02, 0x11, 0xA0, 0x03, 0x02, 0x01, 0x02, 0x02, 0x14, 0x25, 0xEE, 0xEF, 0x9A, 0x4C,
-    0x61, 0xD4, 0xB9, 0xE3, 0xD9, 0x4B, 0xEA, 0x46, 0xF9, 0xA1, 0x2A, 0xC6, 0x88, 0x7C, 0xE2, 0x30,
-    0x0A, 0x06, 0x08, 0x2A, 0x86, 0x48, 0xCE, 0x3D, 0x04, 0x03, 0x03, 0x30, 0x65, 0x31, 0x18, 0x30,
-    0x16, 0x06, 0x03, 0x55, 0x04, 0x03, 0x0C, 0x0F, 0x43, 0x61, 0x6C, 0x69, 0x70, 0x74, 0x72, 0x61,
-    0x20, 0x49, 0x44, 0x65, 0x76, 0x49, 0x44, 0x31, 0x49, 0x30, 0x47, 0x06, 0x03, 0x55, 0x04, 0x05,
-    0x13, 0x40, 0x38, 0x45, 0x33, 0x43, 0x31, 0x41, 0x30, 0x35, 0x38, 0x46, 0x37, 0x30, 0x34, 0x41,
-    0x31, 0x31, 0x38, 0x32, 0x31, 0x46, 0x37, 0x42, 0x34, 0x38, 0x44, 0x33, 0x34, 0x30, 0x41, 0x45,
-    0x46, 0x39, 0x39, 0x44, 0x44, 0x41, 0x42, 0x41, 0x44, 0x43, 0x31, 0x30, 0x39, 0x30, 0x44, 0x37,
-    0x34, 0x44, 0x30, 0x35, 0x37, 0x46, 0x45, 0x43, 0x43, 0x46, 0x37, 0x33, 0x32, 0x39, 0x34, 0x45,
-    0x44, 0x36, 0x30, 0x22, 0x18, 0x0F, 0x32, 0x30, 0x32, 0x33, 0x30, 0x31, 0x30, 0x31, 0x30, 0x30,
-    0x30, 0x30, 0x30, 0x30, 0x5A, 0x18, 0x0F, 0x39, 0x39, 0x39, 0x39, 0x31, 0x32, 0x33, 0x31, 0x32,
-    0x33, 0x35, 0x39, 0x35, 0x39, 0x5A, 0x30, 0x65, 0x31, 0x18, 0x30, 0x16, 0x06, 0x03, 0x55, 0x04,
-    0x03, 0x0C, 0x0F, 0x43, 0x61, 0x6C, 0x69, 0x70, 0x74, 0x72, 0x61, 0x20, 0x4C, 0x44, 0x65, 0x76,
-    0x49, 0x44, 0x31, 0x49, 0x30, 0x47, 0x06, 0x03, 0x55, 0x04, 0x05, 0x13, 0x40, 0x32, 0x31, 0x45,
-    0x45, 0x45, 0x46, 0x39, 0x41, 0x34, 0x43, 0x36, 0x31, 0x44, 0x34, 0x42, 0x39, 0x45, 0x33, 0x44,
-    0x39, 0x34, 0x42, 0x45, 0x41, 0x34, 0x36, 0x46, 0x39, 0x41, 0x31, 0x32, 0x41, 0x43, 0x36, 0x38,
-    0x38, 0x37, 0x43, 0x45, 0x32, 0x31, 0x38, 0x38, 0x35, 0x35, 0x39, 0x46, 0x34, 0x30, 0x46, 0x46,
-    0x39, 0x35, 0x37, 0x37, 0x37, 0x45, 0x38, 0x30, 0x31, 0x34, 0x38, 0x38, 0x39, 0x30, 0x76, 0x30,
-    0x10, 0x06, 0x07, 0x2A, 0x86, 0x48, 0xCE, 0x3D, 0x02, 0x01, 0x06, 0x05, 0x2B, 0x81, 0x04, 0x00,
-    0x22, 0x03, 0x62, 0x00, 0x04, 0x84, 0x2C, 0x00, 0xAF, 0x05, 0xAC, 0xCC, 0xEB, 0x14, 0x51, 0x4E,
-    0x2D, 0x37, 0xB0, 0xC3, 0xAA, 0xA2, 0x18, 0xF1, 0x50, 0x57, 0xF1, 0xDC, 0xB8, 0x24, 0xA2, 0x14,
-    0x98, 0x0B, 0x74, 0x46, 0x88, 0xA0, 0x88, 0x8A, 0x02, 0x97, 0xFA, 0x7D, 0xC5, 0xE1, 0xEA, 0xD8,
-    0xCA, 0x12, 0x91, 0xDB, 0x22, 0x9C, 0x28, 0xEB, 0x86, 0x78, 0xBC, 0xE8, 0x00, 0x82, 0x2C, 0x07,
-    0x22, 0x8F, 0x41, 0x6A, 0xE4, 0x9D, 0x21, 0x8E, 0x5D, 0xA2, 0xF2, 0xD1, 0xA8, 0xA2, 0x7D, 0xC1,
-    0x9A, 0xDF, 0x66, 0x8A, 0x74, 0x62, 0x89, 0x99, 0xD2, 0x22, 0xB4, 0x01, 0x59, 0xD8, 0x07, 0x6F,
-    0xAF, 0xBB, 0x8C, 0x5E, 0xDB, 0xA3, 0x7E, 0x30, 0x7C, 0x30, 0x12, 0x06, 0x03, 0x55, 0x1D, 0x13,
-    0x01, 0x01, 0xFF, 0x04, 0x08, 0x30, 0x06, 0x01, 0x01, 0xFF, 0x02, 0x01, 0x00, 0x30, 0x0E, 0x06,
-    0x03, 0x55, 0x1D, 0x0F, 0x01, 0x01, 0xFF, 0x04, 0x04, 0x03, 0x02, 0x02, 0x04, 0x30, 0x16, 0x06,
-    0x06, 0x67, 0x81, 0x05, 0x05, 0x04, 0x04, 0x04, 0x0C, 0x30, 0x0A, 0x04, 0x08, 0x00, 0x00, 0x00,
-    0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 0x1D, 0x06, 0x03, 0x55, 0x1D, 0x0E, 0x04, 0x16, 0x04, 0x14,
-    0x21, 0xEE, 0xEF, 0x9A, 0x4C, 0x61, 0xD4, 0xB9, 0xE3, 0xD9, 0x4B, 0xEA, 0x46, 0xF9, 0xA1, 0x2A,
-    0xC6, 0x88, 0x7C, 0xE2, 0x30, 0x1F, 0x06, 0x03, 0x55, 0x1D, 0x23, 0x04, 0x18, 0x30, 0x16, 0x80,
-    0x14, 0x42, 0x4F, 0x3A, 0xC7, 0x45, 0xDD, 0xBD, 0x50, 0x15, 0x05, 0x7F, 0x5B, 0xF8, 0x3E, 0x9C,
-    0xD6, 0x48, 0x10, 0xB0, 0x41,
-];
+const FAKE_LDEV_TBS: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/ldev_tbs.der"));
 const FAKE_LDEV_PUB_KEY: Ecc384PubKey = Ecc384PubKey {
     x: Array4xN([
         0x842C00AF, 0x05ACCCEB, 0x14514E2D, 0x37B0C3AA, 0xA218F150, 0x57F1DCB8, 0x24A21498,
@@ -87,14 +52,8 @@ const FAKE_LDEV_PUB_KEY: Ecc384PubKey = Ecc384PubKey {
     ]),
 };
 const FAKE_LDEV_SIG: Ecc384Signature = Ecc384Signature {
-    r: Array4xN([
-        0x0C1B9586, 0x1ADA0DF5, 0x72438E88, 0xB23DDD5B, 0x2C24C974, 0xDF359988, 0xCC54E39E,
-        0x3145635A, 0x94E3D819, 0x6B49164C, 0xAD991714, 0xC2B18892,
-    ]),
-    s: Array4xN([
-        0x4BEDF2A7, 0xDEC94059, 0x64ADF494, 0x9819FADE, 0x2CD785CD, 0x0307078F, 0x74EA4E5C,
-        0xDDF8D1FA, 0xE5380507, 0xAB098713, 0x44CA288F, 0xA6961532,
-    ]),
+    r: Array4xN(include!(concat!(env!("OUT_DIR"), "/ldev_sig_r_words.txt"))),
+    s: Array4xN(include!(concat!(env!("OUT_DIR"), "/ldev_sig_s_words.txt"))),
 };
 
 const FAKE_FMC_ALIAS_TBS: [u8; 745] = [

diff --git a/runtime/tests/integration_tests.rs b/runtime/tests/integration_tests.rs
@@ -35,7 +35,10 @@ use openssl::{
     ecdsa::EcdsaSig,
     nid::Nid,
     pkey::PKey,
-    x509::X509,
+    stack::Stack,
+    x509::{
+        store::X509StoreBuilder, verify::X509VerifyFlags, X509StoreContext, X509VerifyResult, X509,
+    },
 };
 use zerocopy::{AsBytes, FromBytes, LayoutVerified};
 
@@ -158,6 +161,26 @@ fn test_certs() {
             .unwrap(),
         core::cmp::Ordering::Equal
     );
+
+    // Verify full cert chain
+    let mut roots_bldr = X509StoreBuilder::new().unwrap();
+    roots_bldr.add_cert(ldev_cert).unwrap();
+    roots_bldr
+        .set_flags(X509VerifyFlags::X509_STRICT | X509VerifyFlags::PARTIAL_CHAIN)
+        .unwrap();
+    let roots = roots_bldr.build();
+    let mut cert_store = X509StoreContext::new().unwrap();
+    let mut chain = Stack::new().unwrap();
+    chain.push(fmc_cert).unwrap();
+    cert_store
+        .init(&roots, &rt_cert, &chain, |c| {
+            let success = c.verify_cert().unwrap();
+            assert_eq!(c.error(), X509VerifyResult::OK);
+            assert!(success);
+
+            Ok(())
+        })
+        .unwrap();
 }
 
 #[test]

diff --git a/test/tests/smoke_testdata/idevid_csr.der b/test/tests/smoke_testdata/idevid_csr.der
diff --git a/test/tests/smoke_testdata/idevid_csr.txt b/test/tests/smoke_testdata/idevid_csr.txt
@@ -18,16 +18,16 @@ Certificate Request:
         Attributes:
         Requested Extensions:
             X509v3 Basic Constraints: critical
-                CA:TRUE, pathlen:0
+                CA:TRUE, pathlen:5
             X509v3 Key Usage: critical
                 Certificate Sign
             2.23.133.5.4.4: 
                 0
 ..........
     Signature Algorithm: ecdsa-with-SHA384
-         30:64:02:30:29:96:24:94:0f:8b:8f:77:a5:27:42:21:51:bd:
-         66:fd:fc:93:04:e7:c0:57:20:df:15:bf:c2:e0:32:23:21:be:
-         35:e7:2c:8f:ac:4e:05:f0:fe:bc:34:a4:a5:47:7a:79:02:30:
-         0a:87:63:da:eb:fd:9b:07:d8:87:3a:dc:88:0d:66:b4:b6:4d:
-         f7:d7:87:b7:48:46:e1:4e:c2:c6:5f:55:7d:ee:3b:68:26:bb:
-         38:6c:0f:e8:71:91:d0:f9:03:c3:0c:0d
+         30:66:02:31:00:c5:13:78:46:d9:38:27:82:67:db:f2:23:6a:
+         02:4b:a7:6d:19:21:57:e7:04:50:a1:08:6d:f2:ba:66:d7:7f:
+         e6:1e:01:28:93:6e:82:e3:0c:1f:f9:12:33:59:61:23:ce:02:
+         31:00:ae:1e:39:b8:21:79:da:c8:4c:a1:92:4d:06:79:d4:8d:
+         74:34:84:5c:ed:0d:a7:45:58:79:f7:45:21:4a:60:dc:2a:48:
+         21:cc:5f:f7:10:f8:f4:a6:f6:bc:05:31:ea:6a
diff --git a/test/tests/smoke_testdata/ldevid_cert.der b/test/tests/smoke_testdata/ldevid_cert.der
diff --git a/test/tests/smoke_testdata/ldevid_cert.txt b/test/tests/smoke_testdata/ldevid_cert.txt
@@ -24,7 +24,7 @@ Certificate:
                 NIST CURVE: P-384
         X509v3 extensions:
             X509v3 Basic Constraints: critical
-                CA:TRUE, pathlen:0
+                CA:TRUE, pathlen:4
             X509v3 Key Usage: critical
                 Certificate Sign
             2.23.133.5.4.4: 
@@ -36,9 +36,9 @@ Certificate:
                 keyid:42:4F:3A:C7:45:DD:BD:50:15:05:7F:5B:F8:3E:9C:D6:48:10:B0:41
 
     Signature Algorithm: ecdsa-with-SHA384
-         30:64:02:30:0c:1b:95:86:1a:da:0d:f5:72:43:8e:88:b2:3d:
-         dd:5b:2c:24:c9:74:df:35:99:88:cc:54:e3:9e:31:45:63:5a:
-         94:e3:d8:19:6b:49:16:4c:ad:99:17:14:c2:b1:88:92:02:30:
-         4b:ed:f2:a7:de:c9:40:59:64:ad:f4:94:98:19:fa:de:2c:d7:
-         85:cd:03:07:07:8f:74:ea:4e:5c:dd:f8:d1:fa:e5:38:05:07:
-         ab:09:87:13:44:ca:28:8f:a6:96:15:32
+         30:65:02:31:00:ec:d3:24:ac:d4:eb:9c:9f:8f:30:87:c3:92:
+         22:71:4d:27:a7:44:dd:13:9c:b4:19:57:47:bb:c9:6c:23:84:
+         fb:74:ba:d9:10:01:dc:73:e5:56:a1:20:b3:40:18:4f:d9:02:
+         30:0c:98:bb:ca:0b:39:f5:bb:4b:00:19:5d:8a:d6:9b:92:0f:
+         9f:d9:22:ae:1d:7f:ff:81:25:bc:70:2a:7e:77:29:e9:1f:cc:
+         ae:7b:07:15:c5:7a:69:0f:1a:3b:75:12:c9
diff --git a/x509/build/build.rs b/x509/build/build.rs
@@ -40,7 +40,7 @@ fn gen_init_devid_csr(out_dir: &str) {
     let mut usage = KeyUsage::default();
     usage.set_key_cert_sign(true);
     let bldr = csr::CsrTemplateBuilder::<EcdsaSha384Algo>::new()
-        .add_basic_constraints_ext(true, 0)
+        .add_basic_constraints_ext(true, 5)
         .add_key_usage_ext(usage)
         .add_ueid_ext(&[0xFF; 8]);
     let template = bldr.tbs_template("Caliptra IDevID");
@@ -52,7 +52,7 @@ fn gen_local_devid_cert(out_dir: &str) {
     let mut usage = KeyUsage::default();
     usage.set_key_cert_sign(true);
     let bldr = cert::CertTemplateBuilder::<EcdsaSha384Algo>::new()
-        .add_basic_constraints_ext(true, 0)
+        .add_basic_constraints_ext(true, 4)
         .add_key_usage_ext(usage)
         .add_ueid_ext(&[0xFF; 8]);
     let template = bldr.tbs_template("Caliptra LDevID", "Caliptra IDevID");
@@ -63,7 +63,7 @@ fn gen_fmc_alias_cert(out_dir: &str) {
     let mut usage = KeyUsage::default();
     usage.set_key_cert_sign(true);
     let bldr = cert::CertTemplateBuilder::<EcdsaSha384Algo>::new()
-        .add_basic_constraints_ext(true, 0)
+        .add_basic_constraints_ext(true, 3)
         .add_key_usage_ext(usage)
         .add_ueid_ext(&[0xFF; 8])
         .add_fmc_dice_tcb_info_ext(
@@ -95,8 +95,8 @@ fn gen_rt_alias_cert(out_dir: &str) {
     // Add DigitalSignature to allow signing of firmware
     usage.set_digital_signature(true);
     let bldr = cert::CertTemplateBuilder::<EcdsaSha384Algo>::new()
-        // Basic Constraints : CA = true, PathLen = 1
-        .add_basic_constraints_ext(true, 1)
+        // Basic Constraints : CA = true, PathLen = 2
+        .add_basic_constraints_ext(true, 2)
         .add_key_usage_ext(usage)
         .add_ueid_ext(&[0xFF; 8])
         .add_rt_dice_tcb_info_ext(&[FwidParam {