Set rlimits using prlimit in parent

[julz]

Fixes #680

This changes setupRlimit to use the Prlimit syscall (rather than
Setrlimit) and moves the call to the parent process. This is necessary
because Setrlimit would affect the libcontainer consumer if called in
the parent, and would fail if called from the child if the
child process is in a user namespace and the requested rlimit is higher
than that in the parent.

Signed-off-by: Julian Friedman [email protected]

[crosbymichael]

LGTM

nice one!

[mrunalp]

Is there a version that works for both 32/64 bit?

[marcosnils]

@mrunalp seems like golang 386 package uses the same call also for 386 architectures (https://golang.org/src/syscall/zsyscall_linux_386.go?h=prlimit#L766)

[mrunalp]

Thanks!

Sent from my iPhone

On Mar 25, 2016, at 6:08 PM, Marcos Nils [email protected] wrote:

In libcontainer/system/linux.go:

@@ -53,6 +53,14 @@ func Execv(cmd string, args []string, env []string) error {
return syscall.Exec(name, args, env)
}

+func Prlimit(pid, resource int, limit syscall.Rlimit) error {

• _, _, err := syscall.RawSyscall6(syscall.SYS_PRLIMIT64, uintptr(pid), uintptr(resource), uintptr(unsafe.Pointer(&limit)), uintptr(unsafe.Pointer(&limit)), 0, 0)
  @mrunalp seems like golang 386 package uses the same call also for 386 architectures (https://golang.org/src/syscall/zsyscall_linux_386.go?h=prlimit#L766)

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[mrunalp]

LGTM