Check that the firmware version of SNP chips is correct

microsoft · Feb 21, 2025 · a026daf · a026daf
1 parent 9bcb00a
commit a026daf
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diff --git a/include/ccf/pal/attestation.h b/include/ccf/pal/attestation.h
@@ -98,6 +98,84 @@ namespace ccf::pal
         quote.vmpl));
     }
 
+    // Check the FW and Microcode is sufficiently up to date: https://www.amd.com/en/resources/product-security/bulletin/amd-sb-3019.html
+    if (quote.version > 2)
+    {
+      pal::snp::AttestChipModel quote_chip_model = {
+        .family = quote.cpuid_fam_id,
+        .model = quote.cpuid_mod_id,
+        .stepping = quote.cpuid_step,
+      };
+
+      constexpr auto milan_chip_id = pal::snp::get_attest_chip_model(
+        {.stepping = 0x1,
+         .base_model = 0x1,
+         .base_family = 0xF,
+         .extended_model = 0x0,
+         .extended_family = 0x0A});
+      if (
+        quote_chip_model == milan_chip_id &&
+        !(quote.reported_tcb.microcode >= 0xDB &&
+          quote.reported_tcb.snp >= 0x18))
+      {
+        throw std::logic_error(fmt::format(
+          "SEV-SNP: guest attestation report is not from a valid Milan "
+          "processor",
+          quote.reported_tcb));
+      }
+
+      constexpr auto milan_x_chip_id = pal::snp::get_attest_chip_model(
+        {.stepping = 0x2,
+         .base_model = 0x1,
+         .base_family = 0xF,
+         .extended_model = 0x0,
+         .extended_family = 0x0A});
+      if (
+        quote_chip_model == milan_x_chip_id &&
+        !(quote.reported_tcb.microcode >= 0x44 &&
+          quote.reported_tcb.snp >= 0x18))
+      {
+        throw std::logic_error(fmt::format(
+          "SEV-SNP: guest attestation report is not from a valid Milan X"
+          "processor",
+          quote.reported_tcb));
+      }
+
+      constexpr auto genoa_chip_id = pal::snp::get_attest_chip_model(
+        {.stepping = 0x1,
+         .base_model = 0x1,
+         .base_family = 0xF,
+         .extended_model = 0x1,
+         .extended_family = 0x0A});
+      if (
+        quote_chip_model == genoa_chip_id &&
+        !(quote.reported_tcb.microcode >= 0x54 &&
+          quote.reported_tcb.snp >= 0x17))
+      {
+        throw std::logic_error(fmt::format(
+          "SEV-SNP: guest attestation report is not from a valid Genoa "
+          "processor",
+          quote.reported_tcb));
+      }
+
+      constexpr auto genoa_x_chip_id = pal::snp::get_attest_chip_model(
+        {.stepping = 0x2,
+         .base_model = 0x1,
+         .base_family = 0xF,
+         .extended_model = 0x1,
+         .extended_family = 0x0A});
+      if (
+        quote_chip_model == milan_chip_id &&
+        !(quote.reported_tcb.microcode >= 0x4F &&
+          quote.reported_tcb.snp >= 0x17))
+      {
+        throw std::logic_error(fmt::format(
+          "SEV-SNP: guest attestation report is not from a valid Genoa X "
+          "processor",
+          quote.reported_tcb));
+      }
+    }
+
     report_data = SnpAttestationReportData(quote.report_data);
     measurement = SnpAttestationMeasurement(quote.measurement);
 

diff --git a/include/ccf/pal/attestation_sev_snp.h b/include/ccf/pal/attestation_sev_snp.h
@@ -247,4 +247,36 @@ QPHfbkH0CyPfhl1jWhJFZasCAwEAAQ==
 
     virtual ~AttestationInterface() = default;
   };
+
+  #pragma pack(push, 1)
+  struct CPUID
+  {
+    uint8_t stepping : 4;
+    uint8_t base_model : 4;
+    uint8_t base_family : 4;
+    uint8_t reserved : 4;
+    uint8_t extended_model : 4;
+    uint8_t extended_family : 8;
+    uint8_t reserved2 : 4;
+  };
+  static_assert(sizeof(CPUID) == sizeof(uint32_t), "Can't cast CPUID to uint32_t");
+
+  struct AttestChipModel
+  {
+    uint8_t family;
+    uint8_t model;
+    uint8_t stepping;
+
+    bool operator==(const AttestChipModel&) const = default;
+  };
+  #pragma pack(pop)
+
+  constexpr AttestChipModel get_attest_chip_model(const CPUID& cpuid)
+  {
+    AttestChipModel model;
+    model.family = cpuid.base_family + cpuid.extended_family;
+    model.model = (cpuid.extended_model << 4) | cpuid.base_model;
+    model.stepping = cpuid.stepping;
+    return model;
+  }
 }