Fix OpenSSL X509Chain time validity depending on process time zone

src/libraries/Common/src/Interop/Unix/System.Security.Cryptography.Native/Interop.Crypto.cs

@@ -90,13 +90,7 @@ internal static int BioTell(SafeBioHandle bio)
         [LibraryImport(Libraries.CryptoNative)]
         private static partial int CryptoNative_X509StoreSetVerifyTime(
             SafeX509StoreHandle ctx,
-            int year,
-            int month,
-            int day,
-            int hour,
-            int minute,
-            int second,
-            [MarshalAs(UnmanagedType.Bool)] bool isDst);
+            long unixTime);
 
         [LibraryImport(Libraries.CryptoNative, EntryPoint = "CryptoNative_CheckX509IpAddress", StringMarshalling = StringMarshalling.Utf8)]
         internal static partial int CheckX509IpAddress(SafeX509Handle x509, byte[] addressBytes, int addressLen, string hostname, int cchHostname);
@@ -150,21 +144,9 @@ internal static X500DistinguishedName LoadX500Name(IntPtr namePtr)
             return GetNullableDynamicBuffer(GetX509PublicKeyParameterBytes, x509);
         }
 
-        internal static void X509StoreSetVerifyTime(SafeX509StoreHandle ctx, DateTime verifyTime)
+        internal static void X509StoreSetVerifyTime(SafeX509StoreHandle ctx, DateTimeOffset verifyTime)
         {
-            // OpenSSL is going to convert our input time to universal, so we should be in Local or
-            // Unspecified (local-assumed).
-            Debug.Assert(verifyTime.Kind != DateTimeKind.Utc, "UTC verifyTime should have been normalized to Local");
-
-            int succeeded = CryptoNative_X509StoreSetVerifyTime(
-                ctx,
-                verifyTime.Year,
-                verifyTime.Month,
-                verifyTime.Day,
-                verifyTime.Hour,
-                verifyTime.Minute,
-                verifyTime.Second,
-                verifyTime.IsDaylightSavingTime());
+            int succeeded = CryptoNative_X509StoreSetVerifyTime(ctx, verifyTime.ToUnixTimeSeconds());
 
             if (succeeded != 1)
             {

src/libraries/System.Security.Cryptography/src/System/Security/Cryptography/X509Certificates/ChainPal.OpenSsl.cs

@@ -98,14 +98,7 @@ public static void FlushStores()
                 timeout = s_maxUrlRetrievalTimeout;
             }
 
-            // Let Unspecified mean Local, so only convert if the source was UTC.
-            //
-            // Converge on Local instead of UTC because OpenSSL is going to assume we gave it
-            // local time.
-            if (verificationTime.Kind == DateTimeKind.Utc)
-            {
-                verificationTime = verificationTime.ToLocalTime();
-            }
+            DateTimeOffset verificationInstant = new DateTimeOffset(verificationTime);
 
             // Until we support the Disallowed store, ensure it's empty (which is done by the ctor)
             using (new X509Store(StoreName.Disallowed, StoreLocation.CurrentUser, OpenFlags.ReadOnly))
@@ -118,7 +111,7 @@ public static void FlushStores()
                 ((OpenSslX509CertificateReader)cert).SafeHandle,
                 customTrustStore,
                 trustMode,
-                verificationTime,
+                verificationInstant,
                 downloadTimeout);
 
             Interop.Crypto.X509VerifyStatusCode status = chainPal.FindFirstChain(extraStore);

src/libraries/System.Security.Cryptography/src/System/Security/Cryptography/X509Certificates/OpenSslX509ChainProcessor.cs

@@ -46,7 +46,7 @@ internal sealed class OpenSslX509ChainProcessor : IChainPal
         private SafeX509StoreHandle _store;
         private readonly SafeX509StackHandle _untrustedLookup;
         private readonly SafeX509StoreCtxHandle _storeCtx;
-        private readonly DateTime _verificationTime;
+        private readonly DateTimeOffset _verificationTime;
         private readonly TimeSpan _downloadTimeout;
         private WorkingChain? _workingChain;
 
@@ -55,7 +55,7 @@ private OpenSslX509ChainProcessor(
             SafeX509StoreHandle store,
             SafeX509StackHandle untrusted,
             SafeX509StoreCtxHandle storeCtx,
-            DateTime verificationTime,
+            DateTimeOffset verificationTime,
             TimeSpan downloadTimeout)
         {
             _leafHandle = leafHandle;
@@ -95,7 +95,7 @@ internal static OpenSslX509ChainProcessor InitiateChain(
             SafeX509Handle leafHandle,
             X509Certificate2Collection? customTrustStore,
             X509ChainTrustMode trustMode,
-            DateTime verificationTime,
+            DateTimeOffset verificationTime,
             TimeSpan remainingDownloadTime)
         {
             OpenSslCachedSystemStoreProvider.GetNativeCollections(
@@ -401,7 +401,7 @@ internal void ProcessRevocation(
                                     cert,
                                     _store,
                                     revocationMode,
-                                    _verificationTime,
+                                    _verificationTime.LocalDateTime,
                                     _downloadTimeout);
                             }
                         }

src/libraries/System.Security.Cryptography/tests/System.Security.Cryptography.Tests.csproj

@@ -632,6 +632,7 @@
     <Compile Include="X509Certificates\ChainHolder.cs" />
     <Compile Include="X509Certificates\ChainPolicyTests.cs" />
     <Compile Include="X509Certificates\ChainTests.cs" />
+    <Compile Include="X509Certificates\ChainTests.TimeZone.Linux.cs" />
     <Compile Include="X509Certificates\CollectionImportTests.cs" />
     <Compile Include="X509Certificates\CollectionTests.cs" />
     <Compile Include="X509Certificates\ContentTypeTests.cs" />

src/libraries/System.Security.Cryptography/tests/X509Certificates/ChainTests.TimeZone.Linux.cs

@@ -0,0 +1,85 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.DotNet.RemoteExecutor;
+using Xunit;
+
+namespace System.Security.Cryptography.X509Certificates.Tests
+{
+    // Chain time validity must not depend on the process time zone.
+    // OpenSSL/Linux only (Windows/macOS convert the verify time correctly).
+    // RemoteExecutor + TZ isolates the time-zone change to a child process.
+    [PlatformSpecific(TestPlatforms.Linux)]
+    public static class ChainTimeZoneTests
+    {
+        private static readonly DateTimeOffset s_verify = new(2024, 6, 15, 12, 0, 0, TimeSpan.Zero);
+
+        [ConditionalTheory(typeof(RemoteExecutor), nameof(RemoteExecutor.IsSupported))]
+        [InlineData(false)]
+        [InlineData(true)]
+        public static void ValidCert_StaysTimeValidAfterTimeZoneChange(bool asLocal)
+        {
+            RemoteExecutor.Invoke(static asLocalStr =>
+            {
+                // Validity margin (+/-2h) is narrower than the UTC+14 shift below, so the
+                // bug (if present) moves the effective verify time outside the window.
+                using X509Certificate2 cert = MakeCert(s_verify.AddHours(-2), s_verify.AddHours(2));
+                bool asLocal = bool.Parse(asLocalStr);
+
+                SetZone("UTC");
+                Assert.True(IsTimeValid(cert, s_verify, asLocal));
+
+                SetZone("Pacific/Kiritimati"); // UTC+14
+                Assert.True(IsTimeValid(cert, s_verify, asLocal));
+            }, asLocal.ToString()).Dispose();
+        }
+
+        [ConditionalTheory(typeof(RemoteExecutor), nameof(RemoteExecutor.IsSupported))]
+        [InlineData(false)]
+        [InlineData(true)]
+        public static void ExpiredCert_StaysNotTimeValidAfterTimeZoneChange(bool asLocal)
+        {
+            RemoteExecutor.Invoke(static asLocalStr =>
+            {
+                // Expired 30 min before s_verify. NotBefore is >14h earlier so the
+                // westward shift (~14h) lands back inside the window (re-entering
+                // validity from the expiry side), not before NotBefore.
+                using X509Certificate2 cert = MakeCert(s_verify.AddHours(-20), s_verify.AddMinutes(-30));
+                bool asLocal = bool.Parse(asLocalStr);
+
+                SetZone("Pacific/Kiritimati"); // UTC+14
+                Assert.False(IsTimeValid(cert, s_verify, asLocal));
+
+                SetZone("UTC"); // westward: "now" moves back ~14h
+                Assert.False(IsTimeValid(cert, s_verify, asLocal));
+            }, asLocal.ToString()).Dispose();
+        }
+
+        internal static void SetZone(string tz)
+        {
+            Environment.SetEnvironmentVariable("TZ", tz);
+            TimeZoneInfo.ClearCachedData();
+        }
+
+        internal static X509Certificate2 MakeCert(DateTimeOffset notBefore, DateTimeOffset notAfter)
+        {
+            using RSA key = RSA.Create(2048);
+            var req = new CertificateRequest("CN=109039", key, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);
+            return req.CreateSelfSigned(notBefore, notAfter);
+        }
+
+        // Verify-time source (Utc vs Local) must not change the verdict.
+        internal static bool IsTimeValid(X509Certificate2 cert, DateTimeOffset verify, bool asLocal)
+        {
+            using ChainHolder holder = new();
+            X509Chain chain = holder.Chain;
+            chain.ChainPolicy.RevocationMode = X509RevocationMode.NoCheck;
+            chain.ChainPolicy.TrustMode = X509ChainTrustMode.CustomRootTrust;
+            chain.ChainPolicy.CustomTrustStore.Add(cert);
+            chain.ChainPolicy.VerificationTime = asLocal ? verify.LocalDateTime : verify.UtcDateTime;
+
+            chain.Build(cert);
+            return (chain.AllStatusFlags() & X509ChainStatusFlags.NotTimeValid) == 0;
+        }
+    }
+}

src/native/libs/System.Security.Cryptography.Native/openssl.c

@@ -38,31 +38,6 @@ c_static_assert(CRYPTO_EX_INDEX_SSL_SESSION == 2);
 // See X509NameType.UrlName
 #define NAME_TYPE_URL 5
 
-/*
-Function:
-MakeTimeT
-
-Used to convert the constituent elements of a struct tm into a time_t. As time_t does not have
-a guaranteed blitting size, this function is static and cannot be p/invoked. It is here merely
-as a utility.
-
-Return values:
-A time_t representation of the input date. See also man mktime(3).
-*/
-static time_t
-MakeTimeT(int32_t year, int32_t month, int32_t day, int32_t hour, int32_t minute, int32_t second, int32_t isDst)
-{
-    struct tm currentTm;
-    currentTm.tm_year = year - 1900;
-    currentTm.tm_mon = month - 1;
-    currentTm.tm_mday = day;
-    currentTm.tm_hour = hour;
-    currentTm.tm_min = minute;
-    currentTm.tm_sec = second;
-    currentTm.tm_isdst = isDst;
-    return mktime(&currentTm);
-}
-
 /*
 Function:
 GetX509Thumbprint
@@ -914,20 +889,14 @@ void CryptoNative_RecursiveFreeX509Stack(STACK_OF(X509) * stack)
 SetX509StoreVerifyTime
 
 Used by System.Security.Cryptography.X509Certificates' OpenSslX509ChainProcessor to assign the
-verification time to the chain building.  The input is in LOCAL time, not UTC.
+verification time to the chain building. The input is an absolute instant as Unix time
+(seconds since 1970-01-01 UTC), directly convertible to a time_t value.
 
 Return values:
-0 if ctx is NULL, if ctx has no X509_VERIFY_PARAM, or the date inputs don't produce a valid time_t;
+0 if ctx is NULL, if ctx has no X509_VERIFY_PARAM, or if the time is out of bounds on a 32-bit time environment.
 1 on success.
 */
-int32_t CryptoNative_X509StoreSetVerifyTime(X509_STORE* ctx,
-                                            int32_t year,
-                                            int32_t month,
-                                            int32_t day,
-                                            int32_t hour,
-                                            int32_t minute,
-                                            int32_t second,
-                                            int32_t isDst)
+int32_t CryptoNative_X509StoreSetVerifyTime(X509_STORE* ctx, int64_t unixTime)
 {
     ERR_clear_error();
 
@@ -936,12 +905,7 @@ int32_t CryptoNative_X509StoreSetVerifyTime(X509_STORE* ctx,
         return 0;
     }
 
-    time_t verifyTime = MakeTimeT(year, month, day, hour, minute, second, isDst);
-
-    if (verifyTime == (time_t)-1)
-    {
-        return 0;
-    }
+    time_t verifyTime = (time_t)unixTime;
 
     X509_VERIFY_PARAM* verifyParams = X509_STORE_get0_param(ctx);
 

src/native/libs/System.Security.Cryptography.Native/openssl.h

@@ -42,14 +42,7 @@ PALEXPORT X509* CryptoNative_GetX509StackField(STACK_OF(X509) * stack, int loc);
 
 PALEXPORT void CryptoNative_RecursiveFreeX509Stack(STACK_OF(X509) * stack);
 
-PALEXPORT int32_t CryptoNative_X509StoreSetVerifyTime(X509_STORE* ctx,
-                                                      int32_t year,
-                                                      int32_t month,
-                                                      int32_t day,
-                                                      int32_t hour,
-                                                      int32_t minute,
-                                                      int32_t second,
-                                                      int32_t isDst);
+PALEXPORT int32_t CryptoNative_X509StoreSetVerifyTime(X509_STORE* ctx, int64_t unixTime);
 
 PALEXPORT X509* CryptoNative_ReadX509AsDerFromBio(BIO* bio);