go/api/next/51246.txt
Kir Kolyshkin bca17d16ca syscall: add CgroupFD support for ForkExec on Linux
Implement CLONE_INTO_CGROUP feature, allowing to put a child in a
specified cgroup in a clean and simple way. Note that the feature only
works for cgroup v2, and requires Linux kernel 5.7 or newer.

Using the feature requires a new syscall, clone3. Currently this is the
only reason to use clone3, but the code is structured in a way so that
other cases may be easily added in the future.

Add a test case.

While at it, try to simplify the syscall calling code in
forkAndExecInChild1, which became complicated over time because:

1. It was using either rawVforkSyscall or RawSyscall6 depending on
   whether CLONE_NEWUSER was set.

2. On Linux/s390, the first two arguments to clone(2) system call are
   swapped (which deserved a mention in Linux ABI hall of shame). It
   was worked around in rawVforkSyscall on s390, but had to be
   implemented via a switch/case when using RawSyscall6, making the code
   less clear.

Let's

 - modify rawVforkSyscall to have two arguments (which is also required
   for clone3);

 - remove the arguments workaround from s390 asm, instead implementing
   arguments swap in the caller (which still looks ugly but at least
   it's done once and is clearly documented now);

 - use rawVforkSyscall for all cases (since it is essentially similar to
   RawSyscall6, except for having less parameters, not returning r2, and
   saving/restoring the return address before/after syscall on 386 and
   amd64).

Updates #51246.

Change-Id: Ifcd418ebead9257177338ffbcccd0bdecb94474e
Reviewed-on: https://go-review.googlesource.com/c/go/+/417695
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Run-TryBot: Kirill Kolyshkin <kolyshkin@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
2022-09-09 15:34:16 +00:00

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pkg syscall (linux-386), const CLONE_CLEAR_SIGHAND = 4294967296 #51246
pkg syscall (linux-386), const CLONE_CLEAR_SIGHAND ideal-int #51246
pkg syscall (linux-386), const CLONE_INTO_CGROUP = 8589934592 #51246
pkg syscall (linux-386), const CLONE_INTO_CGROUP ideal-int #51246
pkg syscall (linux-386), const CLONE_NEWCGROUP = 33554432 #51246
pkg syscall (linux-386), const CLONE_NEWCGROUP ideal-int #51246
pkg syscall (linux-386), const CLONE_NEWTIME = 128 #51246
pkg syscall (linux-386), const CLONE_NEWTIME ideal-int #51246
pkg syscall (linux-386), const CLONE_PIDFD = 4096 #51246
pkg syscall (linux-386), const CLONE_PIDFD ideal-int #51246
pkg syscall (linux-386), type SysProcAttr struct, CgroupFD int #51246
pkg syscall (linux-386), type SysProcAttr struct, UseCgroupFD bool #51246
pkg syscall (linux-386-cgo), const CLONE_CLEAR_SIGHAND = 4294967296 #51246
pkg syscall (linux-386-cgo), const CLONE_CLEAR_SIGHAND ideal-int #51246
pkg syscall (linux-386-cgo), const CLONE_INTO_CGROUP = 8589934592 #51246
pkg syscall (linux-386-cgo), const CLONE_INTO_CGROUP ideal-int #51246
pkg syscall (linux-386-cgo), const CLONE_NEWCGROUP = 33554432 #51246
pkg syscall (linux-386-cgo), const CLONE_NEWCGROUP ideal-int #51246
pkg syscall (linux-386-cgo), const CLONE_NEWTIME = 128 #51246
pkg syscall (linux-386-cgo), const CLONE_NEWTIME ideal-int #51246
pkg syscall (linux-386-cgo), const CLONE_PIDFD = 4096 #51246
pkg syscall (linux-386-cgo), const CLONE_PIDFD ideal-int #51246
pkg syscall (linux-386-cgo), type SysProcAttr struct, CgroupFD int #51246
pkg syscall (linux-386-cgo), type SysProcAttr struct, UseCgroupFD bool #51246
pkg syscall (linux-amd64), const CLONE_CLEAR_SIGHAND = 4294967296 #51246
pkg syscall (linux-amd64), const CLONE_CLEAR_SIGHAND ideal-int #51246
pkg syscall (linux-amd64), const CLONE_INTO_CGROUP = 8589934592 #51246
pkg syscall (linux-amd64), const CLONE_INTO_CGROUP ideal-int #51246
pkg syscall (linux-amd64), const CLONE_NEWCGROUP = 33554432 #51246
pkg syscall (linux-amd64), const CLONE_NEWCGROUP ideal-int #51246
pkg syscall (linux-amd64), const CLONE_NEWTIME = 128 #51246
pkg syscall (linux-amd64), const CLONE_NEWTIME ideal-int #51246
pkg syscall (linux-amd64), const CLONE_PIDFD = 4096 #51246
pkg syscall (linux-amd64), const CLONE_PIDFD ideal-int #51246
pkg syscall (linux-amd64), type SysProcAttr struct, CgroupFD int #51246
pkg syscall (linux-amd64), type SysProcAttr struct, UseCgroupFD bool #51246
pkg syscall (linux-amd64-cgo), const CLONE_CLEAR_SIGHAND = 4294967296 #51246
pkg syscall (linux-amd64-cgo), const CLONE_CLEAR_SIGHAND ideal-int #51246
pkg syscall (linux-amd64-cgo), const CLONE_INTO_CGROUP = 8589934592 #51246
pkg syscall (linux-amd64-cgo), const CLONE_INTO_CGROUP ideal-int #51246
pkg syscall (linux-amd64-cgo), const CLONE_NEWCGROUP = 33554432 #51246
pkg syscall (linux-amd64-cgo), const CLONE_NEWCGROUP ideal-int #51246
pkg syscall (linux-amd64-cgo), const CLONE_NEWTIME = 128 #51246
pkg syscall (linux-amd64-cgo), const CLONE_NEWTIME ideal-int #51246
pkg syscall (linux-amd64-cgo), const CLONE_PIDFD = 4096 #51246
pkg syscall (linux-amd64-cgo), const CLONE_PIDFD ideal-int #51246
pkg syscall (linux-amd64-cgo), type SysProcAttr struct, CgroupFD int #51246
pkg syscall (linux-amd64-cgo), type SysProcAttr struct, UseCgroupFD bool #51246
pkg syscall (linux-arm), const CLONE_CLEAR_SIGHAND = 4294967296 #51246
pkg syscall (linux-arm), const CLONE_CLEAR_SIGHAND ideal-int #51246
pkg syscall (linux-arm), const CLONE_INTO_CGROUP = 8589934592 #51246
pkg syscall (linux-arm), const CLONE_INTO_CGROUP ideal-int #51246
pkg syscall (linux-arm), const CLONE_NEWCGROUP = 33554432 #51246
pkg syscall (linux-arm), const CLONE_NEWCGROUP ideal-int #51246
pkg syscall (linux-arm), const CLONE_NEWTIME = 128 #51246
pkg syscall (linux-arm), const CLONE_NEWTIME ideal-int #51246
pkg syscall (linux-arm), const CLONE_PIDFD = 4096 #51246
pkg syscall (linux-arm), const CLONE_PIDFD ideal-int #51246
pkg syscall (linux-arm), type SysProcAttr struct, CgroupFD int #51246
pkg syscall (linux-arm), type SysProcAttr struct, UseCgroupFD bool #51246
pkg syscall (linux-arm-cgo), const CLONE_CLEAR_SIGHAND = 4294967296 #51246
pkg syscall (linux-arm-cgo), const CLONE_CLEAR_SIGHAND ideal-int #51246
pkg syscall (linux-arm-cgo), const CLONE_INTO_CGROUP = 8589934592 #51246
pkg syscall (linux-arm-cgo), const CLONE_INTO_CGROUP ideal-int #51246
pkg syscall (linux-arm-cgo), const CLONE_NEWCGROUP = 33554432 #51246
pkg syscall (linux-arm-cgo), const CLONE_NEWCGROUP ideal-int #51246
pkg syscall (linux-arm-cgo), const CLONE_NEWTIME = 128 #51246
pkg syscall (linux-arm-cgo), const CLONE_NEWTIME ideal-int #51246
pkg syscall (linux-arm-cgo), const CLONE_PIDFD = 4096 #51246
pkg syscall (linux-arm-cgo), const CLONE_PIDFD ideal-int #51246
pkg syscall (linux-arm-cgo), type SysProcAttr struct, CgroupFD int #51246
pkg syscall (linux-arm-cgo), type SysProcAttr struct, UseCgroupFD bool #51246