x/sys/unix: Add UMOUNT_NOFOLLOW constant

[schmichael]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

go version go1.7.3 linux/amd64

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/schmichael/go"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build019656358=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"

Enhancement

Add UMOUNT_NOFOLLOW = 0x8 constant to prevent symlink traversal attacks when unmounting filesystems.

Present since Linux 2.6.34: torvalds/linux@db1f05b

[ianlancetaylor]

Want to send a patch? https://golang.org/doc/contribute.html

[gopherbot]

CL https://golang.org/cl/46771 mentions this issue.