mirror of
https://github.com/opencontainers/runc.git
synced 2026-07-11 22:37:14 +08:00
Alexander Larsson
f6028219a5
Sometimes I was getting: 2014/06/13 13:47:24 finalize namespace drop bounding set read /proc/1/status: bad file descriptor This happens when applying the capabilities, and the code that reads the current caps opens /proc/1/status and then reads some data from it. But during this it gets a EBADFD error. The problem is that FinalizeNamespace() closes all FDs before applying the caps, and if a GC then happens after /proc/1/status is opened but before reading from the fd, then an old os.File finalizer may close the already closed-and-reused fd, wreaking havoc. We fix this by instead of closing the FDs we mark them close-on-exec which guarantees that they will be closed when we do the final exec into the container. Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
56 lines
1.4 KiB
Go
56 lines
1.4 KiB
Go
package utils
|
|
|
|
import (
|
|
"crypto/rand"
|
|
"encoding/hex"
|
|
"io"
|
|
"io/ioutil"
|
|
"path/filepath"
|
|
"strconv"
|
|
"syscall"
|
|
)
|
|
|
|
// GenerateRandomName returns a new name joined with a prefix. This size
|
|
// specified is used to truncate the randomly generated value
|
|
func GenerateRandomName(prefix string, size int) (string, error) {
|
|
id := make([]byte, 32)
|
|
if _, err := io.ReadFull(rand.Reader, id); err != nil {
|
|
return "", err
|
|
}
|
|
return prefix + hex.EncodeToString(id)[:size], nil
|
|
}
|
|
|
|
// ResolveRootfs ensures that the current working directory is
|
|
// not a symlink and returns the absolute path to the rootfs
|
|
func ResolveRootfs(uncleanRootfs string) (string, error) {
|
|
rootfs, err := filepath.Abs(uncleanRootfs)
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
return filepath.EvalSymlinks(rootfs)
|
|
}
|
|
|
|
func CloseExecFrom(minFd int) error {
|
|
fdList, err := ioutil.ReadDir("/proc/self/fd")
|
|
if err != nil {
|
|
return err
|
|
}
|
|
for _, fi := range fdList {
|
|
fd, err := strconv.Atoi(fi.Name())
|
|
if err != nil {
|
|
// ignore non-numeric file names
|
|
continue
|
|
}
|
|
|
|
if fd < minFd {
|
|
// ignore descriptors lower than our specified minimum
|
|
continue
|
|
}
|
|
|
|
// intentionally ignore errors from syscall.CloseOnExec
|
|
syscall.CloseOnExec(fd)
|
|
// the cases where this might fail are basically file descriptors that have already been closed (including and especially the one that was created when ioutil.ReadDir did the "opendir" syscall)
|
|
}
|
|
return nil
|
|
}
|