Update as discussed

Author: neha-bhargava

src/client/Microsoft.Identity.Client/ManagedIdentity/AzureArcManagedIdentitySource.cs

@@ -138,36 +138,18 @@ private void ValidateSplitChallenge(string[] splitChallenge)
             }
 
             _requestContext.Logger.Verbose(() => $"[Managed Identity] Challenge is valid. FilePath: {splitChallenge[1]}");
+            string path = Path.GetFullPath(new Uri(splitChallenge[1]).LocalPath)
+                .TrimEnd(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar);
 
-            if (DesktopOsHelper.IsWindows())
-            {
-                if (!IsValidWindowsPath(splitChallenge[1]))
-                {
-                    throw CreateManagedIdentityException(
-                        MsalError.ManagedIdentityRequestFailed,
-                        MsalErrorMessage.ManagedIdentityInvalidFile);
-                }
-
-                _requestContext.Logger.Verbose(() => "[Managed Identity] Windows path is valid.");
-            }
-            else if (DesktopOsHelper.IsLinux())
-            {
-                if (!IsValidLinuxPath(splitChallenge[1]))
-                {
-                    throw CreateManagedIdentityException(
-                        MsalError.ManagedIdentityRequestFailed,
-                        MsalErrorMessage.ManagedIdentityInvalidFile);
-                }
-
-                _requestContext.Logger.Verbose(() => "[Managed Identity] Linux path is valid.");
-            }
-            else
+            if (!IsValidPath(splitChallenge[1]))
             {
                 throw CreateManagedIdentityException(
                     MsalError.ManagedIdentityRequestFailed,
-                    MsalErrorMessage.ManagedIdentityPlatformNotSupported);
+                    MsalErrorMessage.ManagedIdentityInvalidFile);
             }
 
+            _requestContext.Logger.Verbose(() => $"[Managed Identity] File path is valid. Path: {path}");
+
             var length = new FileInfo(splitChallenge[1]).Length;
 
             if ((!File.Exists(splitChallenge[1]) || (length) > 4096))
@@ -191,19 +173,28 @@ private MsalException CreateManagedIdentityException(string errorCode, string er
                 null);
         }
 
-        private bool IsValidLinuxPath(string path)
+        private bool IsValidPath(string path)
         {
-            string linuxPath = "/var/opt/azcmagent/tokens/";
+            string expectedFilePath;
 
-            return path.StartsWith(linuxPath, StringComparison.OrdinalIgnoreCase) && 
-                path.EndsWith(".key", StringComparison.OrdinalIgnoreCase);
-        }
+            if (DesktopOsHelper.IsWindows())
+            {
+                string expandedExpectedPath = Environment.ExpandEnvironmentVariables("%ProgramData%\\AzureConnectedMachineAgent\\Tokens\\");
 
-        private bool IsValidWindowsPath(string path)
-        {
-            string expandedExpectedPath = Environment.ExpandEnvironmentVariables("%ProgramData%\\AzureConnectedMachineAgent\\Tokens\\");
+                expectedFilePath = expandedExpectedPath + Path.GetFileName(path);
+            }
+            else if (DesktopOsHelper.IsLinux())
+            {
+                expectedFilePath = "/var/opt/azcmagent/tokens/" + Path.GetFileName(path);
+            }
+            else
+            {
+                throw CreateManagedIdentityException(
+                    MsalError.ManagedIdentityRequestFailed,
+                    MsalErrorMessage.ManagedIdentityPlatformNotSupported);
+            }
 
-            return path.StartsWith(expandedExpectedPath, StringComparison.OrdinalIgnoreCase) && 
+            return path.Equals(expectedFilePath, StringComparison.OrdinalIgnoreCase) &&
                 path.EndsWith(".key", StringComparison.OrdinalIgnoreCase);
         }
     }

tests/Microsoft.Identity.Test.Unit/ManagedIdentityTests/AzureArcTests.cs

@@ -81,7 +81,8 @@ await mi.AcquireTokenForManagedIdentity("scope")
 
         [DataTestMethod]
         [DataRow("somefile=filename", MsalErrorMessage.ManagedIdentityInvalidChallenge)]
-        [DataRow("path/filename", MsalErrorMessage.ManagedIdentityInvalidFile)]
+        [DataRow("C:\\ProgramData\\AzureConnectedMachineAgent\\Tokens\\filename.txt", MsalErrorMessage.ManagedIdentityInvalidFile)]
+        [DataRow("C:\\ProgramData\\AzureConnectedMachineAgent\\Tokens\\...\\etc\\filename.key", MsalErrorMessage.ManagedIdentityInvalidFile)]
         public async Task AzureArcAuthHeaderInvalidAsync(string filename, string errorMessage)
         {
             using (new EnvVariableContext())
@@ -97,7 +98,7 @@ public async Task AzureArcAuthHeaderInvalidAsync(string filename, string errorMe
 
                 var mi = miBuilder.Build();
 
-                httpManager.AddManagedIdentityWSTrustMockHandler(ManagedIdentityTests.AzureArcEndpoint, "somevalue=filepath");
+                httpManager.AddManagedIdentityWSTrustMockHandler(ManagedIdentityTests.AzureArcEndpoint, filename);
 
                 MsalServiceException ex = await Assert.ThrowsExceptionAsync<MsalServiceException>(async () =>
                     await mi.AcquireTokenForManagedIdentity("scope")
@@ -106,7 +107,7 @@ await mi.AcquireTokenForManagedIdentity("scope")
                 Assert.IsNotNull(ex);
                 Assert.AreEqual(ManagedIdentitySource.AzureArc.ToString(), ex.AdditionalExceptionData[MsalException.ManagedIdentitySource]);
                 Assert.AreEqual(MsalError.ManagedIdentityRequestFailed, ex.ErrorCode);
-                Assert.AreEqual(MsalErrorMessage.ManagedIdentityInvalidChallenge, ex.Message);
+                Assert.AreEqual(errorMessage, ex.Message);
             }
         }