Test the format of patch level device info

On top of checking that the patch level are a UINT, also check that they
follow the YYYYMM or YYYYMMDD format in the CSR v3 as is required by the
server validation logic. This check is not applied in the factory as the
value might not yet be correctly provisioned.

Bug: 269813991
Test: atest VtsHalRemotelyProvisionedComponentTargetTest
Change-Id: I5c62ba176dae390ea0a387bba6cb975226e3873a
diff --git a/security/keymint/support/remote_prov_utils.cpp b/security/keymint/support/remote_prov_utils.cpp
index c9c3e4d..780c3d2 100644
--- a/security/keymint/support/remote_prov_utils.cpp
+++ b/security/keymint/support/remote_prov_utils.cpp
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include <iomanip>
 #include <iterator>
 #include <memory>
 #include <set>
@@ -420,6 +421,36 @@
     return entryName + " has an invalid value.\n";
 }
 
+std::string checkMapPatchLevelEntry(bool isFactory, const cppbor::Map& devInfo,
+                                    const std::string& entryName) {
+    std::string error = checkMapEntry(isFactory, devInfo, cppbor::UINT, entryName);
+    if (!error.empty()) {
+        return error;
+    }
+
+    if (isFactory) {
+        return "";
+    }
+
+    const std::unique_ptr<cppbor::Item>& val = devInfo.get(entryName);
+    std::string dateString = std::to_string(val->asUint()->unsignedValue());
+    if (dateString.size() == 6) {
+        dateString += "01";
+    }
+    if (dateString.size() != 8) {
+        return entryName + " should in the format YYYYMMDD or YYYYMM\n";
+    }
+
+    std::tm t;
+    std::istringstream ss(dateString);
+    ss >> std::get_time(&t, "%Y%m%d");
+    if (!ss) {
+        return entryName + " should in the format YYYYMMDD or YYYYMM\n";
+    }
+
+    return "";
+}
+
 bool isTeeDeviceInfo(const cppbor::Map& devInfo) {
     return devInfo.get("security_level") && devInfo.get("security_level")->asTstr() &&
            devInfo.get("security_level")->asTstr()->value() == "tee";
@@ -520,6 +551,10 @@
                     error += "Err: Unrecognized key entry: <" + key->asTstr()->value() + ">,\n";
                 }
             }
+            // Checks that only apply to v3.
+            error += checkMapPatchLevelEntry(isFactory, *parsed, "system_patch_level");
+            error += checkMapPatchLevelEntry(isFactory, *parsed, "boot_patch_level");
+            error += checkMapPatchLevelEntry(isFactory, *parsed, "vendor_patch_level");
             FALLTHROUGH_INTENDED;
         case 2:
             for (const auto& entry : kAttestationIdEntrySet) {