On Mon, Nov 3, 2014 at 9:37 AM, David Drysdale <drysdale@xxxxxxxxxx> wrote: > On Mon, Nov 3, 2014 at 3:42 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote: >> This is extremely useful in conjunction with seccomp. > > Yes, that was my understanding of how the Chrome[OS] folk wanted > to use it. Yes, exactly. Without this, if we want to give a sandboxed process A access to a directory, we need to: 1. Create a new 'broker" process B 2. Make sure to have an IPC channel between A and B. 3. SIGSYS open() and openat() in A via seccomp-bpf 4. Have an async-signal-safe handler that can IPC open / openat. There is a lot of hidden complexity in such a set-up. For instance, if you need to prevent contention, the number of threads in the broker B should scale automatically. This is 'fine' (but undesirable) for a big beast such as Chromium which needs such a complex set-ups anyways, but David's patch would make it a lot easier to build a sandbox and whitelist directories for everyone, simply by enforcing O_BENEATH in seccomp and whitelisting open directory file descriptors in the sandboxed process. Julien -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
