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using System.Security.AccessControl;
using System.Security.Principal;
using Agent.Windows.Recovery;
namespace Agent.Windows.Security;
public sealed record AclSnapshot(string Path, byte[] SecurityDescriptor, Guid? JournalEntryId = null);
public sealed class TaskAclManager(SecurityIdentifier appContainerSid, ISecurityAuditSink audit, TaskResourceJournal? journal = null)
{
public AclSnapshot Grant(Guid taskId, string path, FileCapability capabilities)
{
string canonical = CanonicalPath.Resolve(path);
FileSystemSecurity security = ReadSecurity(canonical);
byte[] original = security.GetSecurityDescriptorBinaryForm();
Guid? journalEntry = journal?.Prepare("acl", canonical, new Dictionary<string, string>
{
["security_descriptor"] = Convert.ToBase64String(original)
});
FileSystemRights rights = ToRights(capabilities);
if (rights == 0) throw new ArgumentOutOfRangeException(nameof(capabilities));
bool directory = Directory.Exists(canonical);
var rule = new FileSystemAccessRule(appContainerSid, rights,
directory ? InheritanceFlags.ContainerInherit | InheritanceFlags.ObjectInherit : InheritanceFlags.None,
PropagationFlags.None, AccessControlType.Allow);
security.AddAccessRule(rule);
WriteSecurity(canonical, security);
if (journalEntry is not null) journal!.MarkApplied(journalEntry.Value);
audit.Write(new(DateTimeOffset.UtcNow, taskId, "acl.apply", "applied", new Dictionary<string, string>
{
["path"] = canonical,
["sid"] = appContainerSid.Value,
["rights"] = rights.ToString(),
["scope"] = directory ? "root_inheritance" : "file"
}));
return new(canonical, original, journalEntry);
}
public void Restore(Guid taskId, AclSnapshot snapshot)
{
FileSystemSecurity security = Directory.Exists(snapshot.Path) ? new DirectorySecurity() : new FileSecurity();
security.SetSecurityDescriptorBinaryForm(snapshot.SecurityDescriptor, AccessControlSections.Access);
WriteSecurity(snapshot.Path, security);
if (snapshot.JournalEntryId is not null) journal!.MarkCleaned(snapshot.JournalEntryId.Value);
audit.Write(new(DateTimeOffset.UtcNow, taskId, "acl.restore", "restored", new Dictionary<string, string> { ["path"] = snapshot.Path }));
}
private static FileSystemSecurity ReadSecurity(string path) => Directory.Exists(path)
? FileSystemAclExtensions.GetAccessControl(new DirectoryInfo(path), AccessControlSections.Access)
: FileSystemAclExtensions.GetAccessControl(new FileInfo(path), AccessControlSections.Access);
private static void WriteSecurity(string path, FileSystemSecurity security)
{
if (security is DirectorySecurity directorySecurity) FileSystemAclExtensions.SetAccessControl(new DirectoryInfo(path), directorySecurity);
else FileSystemAclExtensions.SetAccessControl(new FileInfo(path), (FileSecurity)security);
}
private static FileSystemRights ToRights(FileCapability capabilities)
{
FileSystemRights rights = 0;
if ((capabilities & FileCapability.Read) != 0) rights |= FileSystemRights.ReadAndExecute | FileSystemRights.ListDirectory;
if ((capabilities & FileCapability.Write) != 0) rights |= FileSystemRights.Write;
if ((capabilities & FileCapability.Execute) != 0) rights |= FileSystemRights.ReadAndExecute;
if ((capabilities & FileCapability.Delete) != 0) rights |= FileSystemRights.Delete | FileSystemRights.DeleteSubdirectoriesAndFiles;
return rights;
}
}
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