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Author SHA1 Message Date
David Wiesen
5b83799328 windows-sandbox: grant full write mask for allow ACEs 2026-05-11 09:13:22 -07:00

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@@ -173,47 +173,6 @@ pub fn path_mask_allows(
}
}
pub unsafe fn dacl_has_write_allow_for_sid(p_dacl: *mut ACL, psid: *mut c_void) -> bool {
if p_dacl.is_null() {
return false;
}
let mut info: ACL_SIZE_INFORMATION = std::mem::zeroed();
let ok = GetAclInformation(
p_dacl as *const ACL,
&mut info as *mut _ as *mut c_void,
std::mem::size_of::<ACL_SIZE_INFORMATION>() as u32,
AclSizeInformation,
);
if ok == 0 {
return false;
}
let count = info.AceCount as usize;
for i in 0..count {
let mut p_ace: *mut c_void = std::ptr::null_mut();
if GetAce(p_dacl as *const ACL, i as u32, &mut p_ace) == 0 {
continue;
}
let hdr = &*(p_ace as *const ACE_HEADER);
if hdr.AceType != 0 {
continue; // ACCESS_ALLOWED_ACE_TYPE
}
// Ignore ACEs that are inherit-only (do not apply to the current object)
if (hdr.AceFlags & INHERIT_ONLY_ACE) != 0 {
continue;
}
let ace = &*(p_ace as *const ACCESS_ALLOWED_ACE);
let mask = ace.Mask;
let base = p_ace as usize;
let sid_ptr =
(base + std::mem::size_of::<ACE_HEADER>() + std::mem::size_of::<u32>()) as *mut c_void;
let eq = EqualSid(sid_ptr, psid);
if eq != 0 && (mask & FILE_GENERIC_WRITE) != 0 {
return true;
}
}
false
}
pub unsafe fn dacl_has_write_deny_for_sid(p_dacl: *mut ACL, psid: *mut c_void) -> bool {
if p_dacl.is_null() {
return false;
@@ -374,70 +333,12 @@ pub unsafe fn ensure_allow_write_aces(path: &Path, sids: &[*mut c_void]) -> Resu
ensure_allow_mask_aces(path, sids, WRITE_ALLOW_MASK)
}
/// Adds an allow ACE granting read/write/execute to the given SID on the target path.
/// Adds an allow ACE granting the full sandbox write mask to the given SID on the target path.
///
/// # Safety
/// Caller must ensure `psid` points to a valid SID and `path` refers to an existing file or directory.
pub unsafe fn add_allow_ace(path: &Path, psid: *mut c_void) -> Result<bool> {
let mut p_sd: *mut c_void = std::ptr::null_mut();
let mut p_dacl: *mut ACL = std::ptr::null_mut();
let code = GetNamedSecurityInfoW(
to_wide(path).as_ptr(),
1,
DACL_SECURITY_INFORMATION,
std::ptr::null_mut(),
std::ptr::null_mut(),
&mut p_dacl,
std::ptr::null_mut(),
&mut p_sd,
);
if code != ERROR_SUCCESS {
return Err(anyhow!("GetNamedSecurityInfoW failed: {code}"));
}
// Already has write? Skip costly DACL rewrite.
if dacl_has_write_allow_for_sid(p_dacl, psid) {
if !p_sd.is_null() {
LocalFree(p_sd as HLOCAL);
}
return Ok(false);
}
let mut added = false;
// Always ensure write is present: if an allow ACE exists without write, add one with write+RX.
let trustee = TRUSTEE_W {
pMultipleTrustee: std::ptr::null_mut(),
MultipleTrusteeOperation: 0,
TrusteeForm: TRUSTEE_IS_SID,
TrusteeType: TRUSTEE_IS_UNKNOWN,
ptstrName: psid as *mut u16,
};
let mut explicit: EXPLICIT_ACCESS_W = std::mem::zeroed();
explicit.grfAccessPermissions = FILE_GENERIC_READ | FILE_GENERIC_WRITE | FILE_GENERIC_EXECUTE;
explicit.grfAccessMode = 2; // SET_ACCESS
explicit.grfInheritance = CONTAINER_INHERIT_ACE | OBJECT_INHERIT_ACE;
explicit.Trustee = trustee;
let mut p_new_dacl: *mut ACL = std::ptr::null_mut();
let code2 = SetEntriesInAclW(1, &explicit, p_dacl, &mut p_new_dacl);
if code2 == ERROR_SUCCESS {
let code3 = SetNamedSecurityInfoW(
to_wide(path).as_ptr() as *mut u16,
1,
DACL_SECURITY_INFORMATION,
std::ptr::null_mut(),
std::ptr::null_mut(),
p_new_dacl,
std::ptr::null_mut(),
);
if code3 == ERROR_SUCCESS {
added = !dacl_has_write_allow_for_sid(p_dacl, psid);
}
if !p_new_dacl.is_null() {
LocalFree(p_new_dacl as HLOCAL);
}
}
if !p_sd.is_null() {
LocalFree(p_sd as HLOCAL);
}
Ok(added)
ensure_allow_write_aces(path, &[psid])
}
/// Adds a deny ACE to prevent write/append/delete for the given SID on the target path.