[seL4] Re: Operating Systems built on top of seL4

On 8/1/21, Gernot Heiser wrote:

On 1 Aug 2021, at 10:12, William ML Leslie wrote:

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Wouldn't there be a risk that a Linux system call would present an argument that happens to look like a capability and not get intercepted if system calls were implemented by just catching the existing invalid-syscall exceptions?

Not if you don't have any capabilities mapped into the address space.

Correct, which would be a reasonable design for a legacy subsystem, it forces each syscall to raise an exception. Silly me for not pointing this out in the first place.

I think there are some syscalls that a linux application could issue that would not trigger a fault: * The yield syscall takes no arguments * It looks to me like the non-blocking send syscalls do not raise exceptions I don't know how likely they would be. - JB