Make it easier to add certs to the extra store (#29828)

Author: HaoK

src/Security/Authentication/Certificate/src/CertificateAuthenticationHandler.cs

@@ -212,6 +212,8 @@ private X509ChainPolicy BuildChainPolicy(X509Certificate2 certificate)
                 chainPolicy.TrustMode = Options.ChainTrustValidationMode;
             }
 
+            chainPolicy.ExtraStore.AddRange(Options.AdditionalChainCertificates);
+
             if (!Options.ValidateValidityPeriod)
             {
                 chainPolicy.VerificationFlags |= X509VerificationFlags.IgnoreNotTimeValid;

src/Security/Authentication/Certificate/src/CertificateAuthenticationOptions.cs

@@ -22,6 +22,11 @@ public class CertificateAuthenticationOptions : AuthenticationSchemeOptions
         /// Collection of X509 certificates which are trusted components of the certificate chain.
         /// </summary>
         public X509Certificate2Collection CustomTrustStore { get; set; } = new X509Certificate2Collection();
+        
+        /// <summary>
+        /// Collection of X509 certificates which are added to the X509Chain.ChainPolicy.ExtraStore of the certificate chain.
+        /// </summary>
+        public X509Certificate2Collection AdditionalChainCertificates { get; set; } = new X509Certificate2Collection();
 
         /// <summary>
         /// Method used to validate certificate chains against <see cref="CustomTrustStore"/>.

src/Security/Authentication/Certificate/src/PublicAPI.Unshipped.txt

@@ -1 +1,3 @@
 #nullable enable
+Microsoft.AspNetCore.Authentication.Certificate.CertificateAuthenticationOptions.AdditionalChainCertificates.get -> System.Security.Cryptography.X509Certificates.X509Certificate2Collection!
+Microsoft.AspNetCore.Authentication.Certificate.CertificateAuthenticationOptions.AdditionalChainCertificates.set -> void

src/Security/Authentication/test/CertificateTests.cs

@@ -319,6 +319,41 @@ public async Task VerifyValidClientCertWithTrustedChainAuthenticates()
             Assert.Equal(HttpStatusCode.OK, response.StatusCode);
         }
 
+        [Fact]
+        public async Task VerifyValidClientCertWithAdditionalCertificatesAuthenticates()
+        {
+            using var host = await CreateHost(
+                new CertificateAuthenticationOptions
+                {
+                    Events = successfulValidationEvents,
+                    ChainTrustValidationMode = X509ChainTrustMode.CustomRootTrust,
+                    CustomTrustStore = new X509Certificate2Collection() { Certificates.SelfSignedPrimaryRoot, },
+                    AdditionalChainCertificates = new X509Certificate2Collection() { Certificates.SignedSecondaryRoot },
+                    RevocationMode = X509RevocationMode.NoCheck
+                }, Certificates.SignedClient);
+
+            using var server = host.GetTestServer();
+            var response = await server.CreateClient().GetAsync("https://example.com/");
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        }
+
+        [Fact]
+        public async Task VerifyValidClientCertFailsWithoutAdditionalCertificatesAuthenticates()
+        {
+            using var host = await CreateHost(
+                new CertificateAuthenticationOptions
+                {
+                    Events = successfulValidationEvents,
+                    ChainTrustValidationMode = X509ChainTrustMode.CustomRootTrust,
+                    CustomTrustStore = new X509Certificate2Collection() { Certificates.SelfSignedPrimaryRoot, },
+                    RevocationMode = X509RevocationMode.NoCheck
+                }, Certificates.SignedClient);
+
+            using var server = host.GetTestServer();
+            var response = await server.CreateClient().GetAsync("https://example.com/");
+            Assert.Equal(HttpStatusCode.Forbidden, response.StatusCode);
+        }
+
         [Fact]
         public async Task VerifyHeaderIsUsedIfCertIsNotPresent()
         {
@@ -570,7 +605,7 @@ public async Task VerifyValidationResultCanBeCached(bool cache)
             Assert.Equal(Expected, name.First().Value);
             count = responseAsXml.Elements("claim").Where(claim => claim.Attribute("Type").Value == "ValidationCount");
             Assert.Single(count);
-            var expected = cache ? "1" : "2"; 
+            var expected = cache ? "1" : "2";
             Assert.Equal(expected, count.First().Value);
         }
 
@@ -693,6 +728,7 @@ private static async Task<IHost> CreateHost(
                                 options.RevocationFlag = configureOptions.RevocationFlag;
                                 options.RevocationMode = configureOptions.RevocationMode;
                                 options.ValidateValidityPeriod = configureOptions.ValidateValidityPeriod;
+                                options.AdditionalChainCertificates = configureOptions.AdditionalChainCertificates;
                             });
                         }
                         else