add a default dacl to restricted token to enable reading of pipes (#8280)

this fixes sandbox errors (legacy and elevated) for commands that
include pipes, which the model often favors.

codex-rs/windows-sandbox-rs/src/token.rs

@@ -4,17 +4,29 @@ use anyhow::Result;
 use std::ffi::c_void;
 use windows_sys::Win32::Foundation::CloseHandle;
 use windows_sys::Win32::Foundation::GetLastError;
+use windows_sys::Win32::Foundation::LocalFree;
+use windows_sys::Win32::Foundation::ERROR_SUCCESS;
 use windows_sys::Win32::Foundation::HANDLE;
+use windows_sys::Win32::Foundation::HLOCAL;
 use windows_sys::Win32::Foundation::LUID;
 use windows_sys::Win32::Security::AdjustTokenPrivileges;
+use windows_sys::Win32::Security::Authorization::SetEntriesInAclW;
+use windows_sys::Win32::Security::Authorization::EXPLICIT_ACCESS_W;
+use windows_sys::Win32::Security::Authorization::GRANT_ACCESS;
+use windows_sys::Win32::Security::Authorization::TRUSTEE_IS_SID;
+use windows_sys::Win32::Security::Authorization::TRUSTEE_IS_UNKNOWN;
+use windows_sys::Win32::Security::Authorization::TRUSTEE_W;
 use windows_sys::Win32::Security::CopySid;
 use windows_sys::Win32::Security::CreateRestrictedToken;
 use windows_sys::Win32::Security::CreateWellKnownSid;
 use windows_sys::Win32::Security::GetLengthSid;
 use windows_sys::Win32::Security::GetTokenInformation;
 use windows_sys::Win32::Security::LookupPrivilegeValueW;
+use windows_sys::Win32::Security::SetTokenInformation;
 
+use windows_sys::Win32::Security::TokenDefaultDacl;
 use windows_sys::Win32::Security::TokenGroups;
+use windows_sys::Win32::Security::ACL;
 use windows_sys::Win32::Security::SID_AND_ATTRIBUTES;
 use windows_sys::Win32::Security::TOKEN_ADJUST_DEFAULT;
 use windows_sys::Win32::Security::TOKEN_ADJUST_PRIVILEGES;
@@ -28,9 +40,71 @@ use windows_sys::Win32::System::Threading::GetCurrentProcess;
 const DISABLE_MAX_PRIVILEGE: u32 = 0x01;
 const LUA_TOKEN: u32 = 0x04;
 const WRITE_RESTRICTED: u32 = 0x08;
+const GENERIC_ALL: u32 = 0x1000_0000;
 const WIN_WORLD_SID: i32 = 1;
 const SE_GROUP_LOGON_ID: u32 = 0xC0000000;
 
+#[repr(C)]
+struct TokenDefaultDaclInfo {
+    default_dacl: *mut ACL,
+}
+
+/// Sets a permissive default DACL so sandboxed processes can create pipes/IPC objects
+/// without hitting ACCESS_DENIED when PowerShell builds pipelines.
+unsafe fn set_default_dacl(h_token: HANDLE, sids: &[*mut c_void]) -> Result<()> {
+    if sids.is_empty() {
+        return Ok(());
+    }
+    let entries: Vec<EXPLICIT_ACCESS_W> = sids
+        .iter()
+        .map(|sid| EXPLICIT_ACCESS_W {
+            grfAccessPermissions: GENERIC_ALL,
+            grfAccessMode: GRANT_ACCESS,
+            grfInheritance: 0,
+            Trustee: TRUSTEE_W {
+                pMultipleTrustee: std::ptr::null_mut(),
+                MultipleTrusteeOperation: 0,
+                TrusteeForm: TRUSTEE_IS_SID,
+                TrusteeType: TRUSTEE_IS_UNKNOWN,
+                ptstrName: *sid as *mut u16,
+            },
+        })
+        .collect();
+    let mut p_new_dacl: *mut ACL = std::ptr::null_mut();
+    let res = SetEntriesInAclW(
+        entries.len() as u32,
+        entries.as_ptr(),
+        std::ptr::null_mut(),
+        &mut p_new_dacl,
+    );
+    if res != ERROR_SUCCESS {
+        return Err(anyhow!("SetEntriesInAclW failed: {}", res));
+    }
+    let mut info = TokenDefaultDaclInfo {
+        default_dacl: p_new_dacl,
+    };
+    let ok = SetTokenInformation(
+        h_token,
+        TokenDefaultDacl,
+        &mut info as *mut _ as *mut c_void,
+        std::mem::size_of::<TokenDefaultDaclInfo>() as u32,
+    );
+    if ok == 0 {
+        let err = GetLastError();
+        if !p_new_dacl.is_null() {
+            LocalFree(p_new_dacl as HLOCAL);
+        }
+        return Err(anyhow!(
+            "SetTokenInformation(TokenDefaultDacl) failed: {}",
+            err
+        ));
+    }
+    if !p_new_dacl.is_null() {
+        LocalFree(p_new_dacl as HLOCAL);
+    }
+    Ok(())
+}
+
 pub unsafe fn world_sid() -> Result<Vec<u8>> {
     let mut size: u32 = 0;
     CreateWellKnownSid(
@@ -267,6 +341,7 @@ pub unsafe fn create_workspace_write_token_with_cap_from(
     if ok == 0 {
         return Err(anyhow!("CreateRestrictedToken failed: {}", GetLastError()));
     }
+    set_default_dacl(new_token, &[psid_logon, psid_everyone, psid_capability])?;
     enable_single_privilege(new_token, "SeChangeNotifyPrivilege")?;
     Ok((new_token, psid_capability))
 }
@@ -305,6 +380,7 @@ pub unsafe fn create_readonly_token_with_cap_from(
     if ok == 0 {
         return Err(anyhow!("CreateRestrictedToken failed: {}", GetLastError()));
     }
+    set_default_dacl(new_token, &[psid_logon, psid_everyone, psid_capability])?;
     enable_single_privilege(new_token, "SeChangeNotifyPrivilege")?;
     Ok((new_token, psid_capability))
 }