x/sys/unix: add memfd_secret systemcall

[awnumar]

Linux kernel version 5.14 added the memfd_secret syscall to allow processes to create memory regions that even the kernel itself cannot access. It'd be very useful to have this system-call available in sys/unix.

I see that there's currently a SYS_MEMFD_SECRET = 447 signal defined here, but I'm not sure how this is related to the system-call

[ianlancetaylor]

In general we don't require a proposal for adding a simple system call to x/sys/unix, and memfd_create is a simple system call. Taking this out of the proposal process.

[awnumar]

My apologies. I thought it fit more than the other issue options

and memfd_create is a simple system call

memfd_create is already in x/sys/unix. This issue is about adding memfd_secret

[ianlancetaylor]

Sorry, I meant to write memfd_secret.

[ericlagergren]

I see that there's currently a SYS_MEMFD_SECRET = 447 signal defined here, but I'm not sure how this is related to the system-call

FYI, until a MemfdSecret gets added: https://go.dev/play/p/Lv9D8pg-5mt

[ericlagergren]

I think @gopherbot is taking the day off. Solved by CL 397774 (golang/sys@b1e9470).

[nadoo]

Hi @ericlagergren , there's no SYS_MEMFD_SECRET defined in zsysnum_linux_riscv64.go, so we'll get error when building for riscv64:

../../../go/pkg/mod/golang.org/x/sys@v0.0.0-20220405052023-b1e9470b6e64/unix/zsyscall_linux_riscv64.go:184:23: undefined: SYS_MEMFD_SECRET

[ericlagergren]

@nadoo thanks, sorry about that.

@ianlancetaylor I’ll send a new CL limiting this to just arm64 and amd64 Linux, then.