lua-lsm: add inode_setattr attributes

[chenzongyao200127]

Lua-LSM currently passes nil for the inode_setattr() attributes argument. Policy can see the target idmap and dentry, but cannot tell whether the operation is chmod, chown, truncate, a timestamp update, or another setattr request.

Translate the iattr payload into a Lua table. The table includes the valid mask, mode, uid, gid, size, timestamps, and boolean ATTR_* flags, with uid and gid converted through the mount idmap before they are exposed to Lua.

Example Lua policy:

return {
    name = "setattr-policy",
    author = "Zongyao Chen",
    license = "GPL",

    inode_setattr = function(idmap, dentry, attr)
        local path = dentry:path()

        if attr.size and path and path:match("^/var/log/") then
            return false, errno.EPERM
        end

        if attr.mode and path and path:match("^/etc/") then
            return false, errno.EPERM
        end

        if attr.uid == 0 or attr.gid == 0 then
            return false, errno.EPERM
        end

        return true
    end,
}

Validation:

• ./scripts/checkpatch.pl --git origin/lua-lsm..lua-lsm-inode-setattr
• git diff --check origin/lua-lsm..lua-lsm-inode-setattr

Signed-off-by: Zongyao Chen ZongYao.Chen@linux.alibaba.com