libcontainer:clean cached rlimit nofile in go runtime

As reported in issue #4195, the new version of go runtime will
cache rlimit-nofile. before executing exec, the rlimit-nofile
of the process will be updated with the cache. in runc, this will
cause the rlimit-nofile set by the parent process for the container
to become invalid. this can be solved by clearing the cache.

Signed-off-by: ls-ggg <335814617@qq.com>

libcontainer/setns_init_linux.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
+	"syscall"
 
 	"github.com/opencontainers/selinux/go-selinux"
 	"github.com/sirupsen/logrus"
@@ -49,6 +50,17 @@ func (l *linuxSetnsInit) Init() error {
 			}
 		}
 	}
+
+	// Set RLIMIT_NOFILE again to clean the cache in go runtime
+	// The problem originates from https://github.com/golang/go/commit/f5eef58e4381259cbd84b3f2074c79607fb5c821
+	rlimit := syscall.Rlimit{}
+	if err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rlimit); err != nil {
+		return err
+	}
+	if err := syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rlimit); err != nil {
+		return err
+	}
+
 	if l.config.CreateConsole {
 		if err := setupConsole(l.consoleSocket, l.config, false); err != nil {
 			return err

libcontainer/standard_init_linux.go

@@ -5,18 +5,18 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
-
-	"github.com/opencontainers/runtime-spec/specs-go"
-	"github.com/opencontainers/selinux/go-selinux"
-	"github.com/sirupsen/logrus"
-	"golang.org/x/sys/unix"
+	"syscall"
 
 	"github.com/opencontainers/runc/libcontainer/apparmor"
 	"github.com/opencontainers/runc/libcontainer/configs"
 	"github.com/opencontainers/runc/libcontainer/keys"
 	"github.com/opencontainers/runc/libcontainer/seccomp"
 	"github.com/opencontainers/runc/libcontainer/system"
 	"github.com/opencontainers/runc/libcontainer/utils"
+	"github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/opencontainers/selinux/go-selinux"
+	"github.com/sirupsen/logrus"
+	"golang.org/x/sys/unix"
 )
 
 type linuxStandardInit struct {
@@ -77,6 +77,16 @@ func (l *linuxStandardInit) Init() error {
 		}
 	}
 
+	// Set RLIMIT_NOFILE again to clean the cache in go runtime
+	// The problem originates from https://github.com/golang/go/commit/f5eef58e4381259cbd84b3f2074c79607fb5c821
+	rlimit := syscall.Rlimit{}
+	if err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rlimit); err != nil {
+		return err
+	}
+	if err := syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rlimit); err != nil {
+		return err
+	}
+
 	if err := setupNetwork(l.config); err != nil {
 		return err
 	}

tests/integration/resources.bats

@@ -0,0 +1,22 @@
+#!/usr/bin/env bats
+
+load helpers
+
+function setup() {
+	setup_busybox
+}
+
+function teardown() {
+	teardown_bundle
+}
+
+@test "runc run with RLIMIT_NOFILE" {
+	update_config '.process.args = ["/bin/sh", "-c", "ulimit -n"]'
+	update_config '.process.capabilities.bounding = ["CAP_SYS_RESOURCE"]'
+	update_config '.process.rlimits = [{"type": "RLIMIT_NOFILE", "hard": 10000, "soft": 10000}]'
+
+	runc run test_hello
+	[ "$status" -eq 0 ]
+
+	[[ "${output}" == "10000" ]]
+}