mixedbit

Look at websites: websites are able to fetch code from any remote URL, yet browsers heavily use sandboxing to ensure that if fetched code turns out to be malicious, the users local files, cookies, etc are not exposed.

"They worked in Symantec’s Threat Intelligence Lab in Culver City, the cyber equivalent of a biodefense lab, where researchers could unleash malevolent code on a “red” network—a sandboxed system air-gapped from Symantec’s business network—to observe its hostile behavior in a controlled environment. To reach the ground-floor lab, workers passed through several sets of security doors, each with progressively more restrictive rules. The final gateway kept all but a handful of workers out and physically isolated the red network from computers connected to the outside internet. Portable media were prohibited here—no DVDs, CD-ROMs, or USB flash drives were allowed —to prevent workers from mindlessly slipping one into an infested machine and inadvertently carrying it out of the lab with a malicious specimen stowed away on it."

I agree. One thing I'm doing is to review past security problems in popular sandbox and container related projects and check if they apply to Drop. Drop is also rootless only (it won't even start as root), which helps to cut some classes of problems.

The first Drop version (and the current default runtime) uses Linux namespaces alone to achieve this.

Then, gVisor was added as the second runtime, because it could be done in a way which is completely seamless from the user perspective, both runtimes produce identically looking sandboxes.

A lightweight VM could potentially be a third runtime, but I'm not yet sure it is possible to use a VM in such a way, that the sandbox is configured identically to the first two runtimes. Basically, quickly boot a kernel using the distro already in / and mount the same dirs Drop mounts with two other runtimes. An obvious problem I can already see is that /etc is not fully readable to the user running Drop, so using it to boot a VM will require working around lack of config file access.

Anyway, if VM support was possible, it would obviously have advantage of being fully compatible standard Linux kernel while providing very good isolation of the host kernel. gVisor does have some compatibility issue, as it is re-implementation of the kernel in Go.

Another advantage would be that with VM runtime it would be possible to start containers from Drop, which currently, due to issues related to nested namespaces, is not supported.