Assembly.LoadFile 出错探索! dotnet 权限初探!

最近遇到一个问题,在使用  Assembly.LoadFile 报错, 错误的消息是 访问拒绝!

涉及到dotnet的权限问题,我以前没接触结.果现在被老比尔干了,我现在干干他!

使用工具 vs2005 Reflector

为了方便起见,我已经将mscorlib 反编译了. 将其在vs2005 中打开.

ok let's go!

 

Assembly.LoadFile  方法

 

 1        public static Assembly LoadFile(string path)
 2        {
 3            new FileIOPermission(FileIOPermissionAccess.PathDiscovery | FileIOPermissionAccess.Read, path).Demand();
 4            return nLoadFile(path, null);
 5        }
 6
 7        [SecurityPermission(SecurityAction.Demand, Flags=SecurityPermissionFlag.ControlEvidence)]
 8        public static Assembly LoadFile(string path, System.Security.Policy.Evidence securityEvidence)
 9        {
            new FileIOPermission(FileIOPermissionAccess.PathDiscovery | FileIOPermissionAccess.Read, path).Demand();
            return nLoadFile(path, securityEvidence);
        }

哈哈 这是我调用的 Assembly.LoadFile(DLLFile.ToString());

有一个东东 FileIOPermission  Permission 是么意思??

呵呵 似乎是它

再看看 nLoadFile  貌似 他才是关键

 

 

        [MethodImpl(MethodImplOptions.InternalCall)]
        internal static extern Assembly nLoadFile(string path, System.Security.Policy.Evidence evidence);

 

哈哈 一个原生方法

 

由此可以看出 Assembly.LoadFile  ->nLoadFile  

那末权限检查到底在哪里那?

答案就在 FileIOPermission 和 [SecurityPermission(SecurityAction.Demand, Flags=SecurityPermissionFlag.ControlEvidence)]

至于到底什么 不知道

那末如何解决这个问题那?

看全部打代码(太大了不贴了)

看LoadFrom 函数

 

 

       public static Assembly LoadFrom(string assemblyFile)
        {
            StackCrawlMark lookForMyCaller = StackCrawlMark.LookForMyCaller;
            return InternalLoadFrom(assemblyFile, null, null, AssemblyHashAlgorithm.None, false, ref lookForMyCaller);
        }

        public static Assembly LoadFrom(string assemblyFile, System.Security.Policy.Evidence securityEvidence)
        {
            StackCrawlMark lookForMyCaller = StackCrawlMark.LookForMyCaller;
            return InternalLoadFrom(assemblyFile, securityEvidence, null, AssemblyHashAlgorithm.None, false, ref lookForMyCaller);
        }

        public static Assembly LoadFrom(string assemblyFile, System.Security.Policy.Evidence securityEvidence, byte[] hashValue, AssemblyHashAlgorithm hashAlgorithm)
        {
            StackCrawlMark lookForMyCaller = StackCrawlMark.LookForMyCaller;
            return InternalLoadFrom(assemblyFile, securityEvidence, hashValue, hashAlgorithm, false, ref lookForMyCaller);
        }

 

 好像没有看到权限检查呀!

在看看InternalLoadFrom 

 

 

 

       internal static Assembly InternalLoad(AssemblyName assemblyRef, System.Security.Policy.Evidence assemblySecurity, ref StackCrawlMark stackMark, bool forIntrospection)
        {
            if (assemblyRef == null)
            {
                throw new ArgumentNullException("assemblyRef");
            }
            assemblyRef = (AssemblyName) assemblyRef.Clone();
            if (assemblySecurity != null)
            {
                new SecurityPermission(SecurityPermissionFlag.ControlEvidence).Demand();
            }
            string strA = VerifyCodeBase(assemblyRef.CodeBase);
            if (strA != null)
            {
                if (string.Compare(strA, 0, "file:", 0, 5, StringComparison.OrdinalIgnoreCase) != 0)
                {
                    CreateWebPermission(assemblyRef.EscapedCodeBase).Demand();
                }
                else
                {
                    URLString str2 = new URLString(strA, true);
                    new FileIOPermission(FileIOPermissionAccess.PathDiscovery | FileIOPermissionAccess.Read, str2.GetFileName()).Demand();
                }
            }
            return nLoad(assemblyRef, strA, assemblySecurity, null, ref stackMark, true, forIntrospection);
        }

        internal static Assembly InternalLoad(string assemblyString, System.Security.Policy.Evidence assemblySecurity, ref StackCrawlMark stackMark, bool forIntrospection)
        {
            if (assemblyString == null)
            {
                throw new ArgumentNullException("assemblyString");
            }
            if ((assemblyString.Length == 0) || (assemblyString[0] == '\0'))
            {
                throw new ArgumentException(Environment.GetResourceString("Format_StringZeroLength"));
            }
            AssemblyName assemblyRef = new AssemblyName();
            Assembly assembly = null;
            assemblyRef.Name = assemblyString;
            if (assemblyRef.nInit(out assembly, forIntrospection, true) == -2146234297)
            {
                return assembly;
            }
            return InternalLoad(assemblyRef, assemblySecurity, ref stackMark, forIntrospection);
        }

        private static Assembly InternalLoadFrom(string assemblyFile, System.Security.Policy.Evidence securityEvidence, byte[] hashValue, AssemblyHashAlgorithm hashAlgorithm, bool forIntrospection, ref StackCrawlMark stackMark)
        {
            if (assemblyFile == null)
            {
                throw new ArgumentNullException("assemblyFile");
            }
            AssemblyName assemblyRef = new AssemblyName();
            assemblyRef.CodeBase = assemblyFile;
            assemblyRef.SetHashControl(hashValue, hashAlgorithm);
            return InternalLoad(assemblyRef, securityEvidence, ref stackMark, forIntrospection);
        }

 呵呵 又是一大堆跳跳  InternalLoadFrom -> InternalLoad -> nLoad

最终 跳到

 

 [MethodImpl(MethodImplOptions.InternalCall)]
        private static extern Assembly _nLoad(AssemblyName fileName, string codeBase, System.Security.Policy.Evidence assemblySecurity, Assembly locationHint, ref StackCrawlMark stackMark, bool throwOnFileNotFound, bool forIntrospection);

 

 呵呵优势一个 原生方法

最终解决 LoadFrom 代替 LoadFile 

 

dotnet 的权限似乎 使用 某个类 或者 属性来控制的