C# - Set Folder Permission

1 ) Set Access Control

DirectoryInfo dInfo = new DirectoryInfo(fileName);
DirectorySecurity dSecurity = dInfo.GetAccessControl();
dSecurity.AddAccessRule(new FileSystemAccessRule("everyone",FileSystemRights.FullControl, InheritanceFlags.ObjectInherit | InheritanceFlags.ContainerInherit,PropagationFlags.InheritOnly,AccessControlType.Allow));
dInfo.SetAccessControl(dSecurity);

2) Sharing foldel

ManagementClass mc = new ManagementClass("win32_share");
ManagementBaseObject inParams = mc.GetMethodParameters("Create");
inParams("Description") = "My Shared Folder";
inParams("Name") = "Shared Folder Name";
inParams("Path") = "C:\\Folder1";
inParams("Type") = ShareResourceType.DiskDrive;
inParams("MaximumAllowed") = null;
inParams("Password") = null;
inParams("Access") = null; // Make Everyone has full control access.
ManagementBaseObject outParams = classObj.InvokeMethod("Create", inParams, null);

3) Only in Windows 7 and Vista, upgrade "Everyone" sharing right

//user selection
NTAccount ntAccount = new NTAccount("Everyone");

//SID
SecurityIdentifier userSID = (SecurityIdentifier)ntAccount.Translate(typeof(SecurityIdentifier));
byte[] utenteSIDArray = new byte[userSID.BinaryLength];
userSID.GetBinaryForm(utenteSIDArray, 0);

//Trustee
ManagementObject userTrustee = new ManagementClass(new ManagementPath("Win32_Trustee"), null);
userTrustee["Name"] = "Everyone";
userTrustee["SID"] = utenteSIDArray;

//ACE
ManagementObject userACE = new ManagementClass(new ManagementPath("Win32_Ace"), null);
userACE["AccessMask"] = 2032127;                                 //Full access
userACE["AceFlags"] = AceFlags.ObjectInherit | AceFlags.ContainerInherit;
userACE["AceType"] = AceType.AccessAllowed;
userACE["Trustee"] = userTrustee;

ManagementObject userSecurityDescriptor = new ManagementClass(new ManagementPath("Win32_SecurityDescriptor"), null);
userSecurityDescriptor["ControlFlags"] = 4; //SE_DACL_PRESENT 
userSecurityDescriptor["DACL"] = new object[] { userACE };

//UPGRADE SECURITY PERMISSION
ManagementClass mc = new ManagementClass("Win32_Share");
ManagementObject share = new ManagementObject(mc.Path + ".Name='" + CondivisionName + "'");
share.InvokeMethod("SetShareInfo", new object[] { Int32.MaxValue, description, userSecurityDescriptor });

Setting NTFS Permissions with C# Programmatically

Reference the dll, and use it.

using Microsoft.Win32.Security;

Here's a method to add a dir, and set NTFS permissions on it for a given user:

private Boolean CreateDir(String strSitePath, String strUserName) {
       Boolean bOk;
       try {
              Directory.CreateDirectory(strSitePath);
              SecurityDescriptor secDesc = SecurityDescriptor.GetFileSecurity(strSitePath, SECURITY_INFORMATION.DACL_SECURITY_INFORMATION);
              Dacl dacl = secDesc.Dacl;
              Sid sidUser = new Sid (strUserName);
 
              // allow: folder, subfolder and files
              // modify
              dacl.AddAce (new AceAccessAllowed (sidUser, AccessType.GENERIC_WRITE | AccessType.GENERIC_READ | AccessType.DELETE | AccessType.GENERIC_EXECUTE , AceFlags.OBJECT_INHERIT_ACE | AceFlags.CONTAINER_INHERIT_ACE));
             
              // deny: this folder
              // write attribs
              // write extended attribs
              // delete
              // change permissions
              // take ownership
              DirectoryAccessType DAType = DirectoryAccessType.FILE_WRITE_ATTRIBUTES | DirectoryAccessType.FILE_WRITE_EA | DirectoryAccessType.DELETE | DirectoryAccessType.WRITE_OWNER | DirectoryAccessType.WRITE_DAC;
              AccessType AType = (AccessType)DAType;
              dacl.AddAce (new AceAccessDenied (sidUser, AType));
 
              secDesc.SetDacl(dacl);
              secDesc.SetFileSecurity(strSitePath, SECURITY_INFORMATION.DACL_SECURITY_INFORMATION);
              bOk = true;
       } catch {
              bOk = false;
       }
       return bOk;
} /* CreateDir */

The AceFlags determine the level of inheritance on the object.
And the DirectoryAccessType is used to create a AccessType with some permissions not in the AccessType enum.
I hope this is useful.