tun: freebsd: work around numerous kernel panics on shutdown
There are numerous race conditions. But even this will crash it: while true; do ifconfig tun0 create; ifconfig tun0 destroy; done It seems like LLv6 is related, which we're not using anyway, so explicitly disable it on the interface.
This commit is contained in:
Jason A. Donenfeld
parent
f1dc167901
commit
bb42ec7d18
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@ -19,9 +19,19 @@ import (
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// _TUNSIFHEAD, value derived from sys/net/{if_tun,ioccom}.h
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// const _TUNSIFHEAD = ((0x80000000) | (((4) & ((1 << 13) - 1) ) << 16) | (uint32(byte('t')) << 8) | (96))
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const _TUNSIFHEAD = 0x80047460
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const _TUNSIFMODE = 0x8004745e
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const _TUNSIFPID = 0x2000745f
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const (
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_TUNSIFHEAD = 0x80047460
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_TUNSIFMODE = 0x8004745e
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_TUNSIFPID = 0x2000745f
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)
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//TODO: move into x/sys/unix
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const (
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SIOCGIFINFO_IN6 = 0xc048696c
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SIOCSIFINFO_IN6 = 0xc048696d
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ND6_IFF_AUTO_LINKLOCAL = 0x20
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ND6_IFF_NO_DAD = 0x100
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)
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// Iface status string max len
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const _IFSTATMAX = 800
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@ -32,7 +42,7 @@ const SIZEOF_UINTPTR = 4 << (^uintptr(0) >> 32 & 1)
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type ifreq_ptr struct {
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Name [unix.IFNAMSIZ]byte
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Data uintptr
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Pad0 [24 - SIZEOF_UINTPTR]byte
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Pad0 [16 - SIZEOF_UINTPTR]byte
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}
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// Structure for iface mtu get/set ioctls
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@ -48,6 +58,23 @@ type ifstat struct {
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Ascii [_IFSTATMAX]byte
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}
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// Structures for nd6 flag manipulation
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type in6_ndireq struct {
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Name [unix.IFNAMSIZ]byte
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Linkmtu uint32
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Maxmtu uint32
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Basereachable uint32
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Reachable uint32
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Retrans uint32
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Flags uint32
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Recalctm int
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Chlim uint8
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Initialized uint8
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Randomseed0 [8]byte
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Randomseed1 [8]byte
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Randomid [8]byte
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}
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type NativeTun struct {
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name string
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tunFile *os.File
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@ -191,23 +218,18 @@ func tunName(fd uintptr) (string, error) {
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// Destroy a named system interface
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func tunDestroy(name string) error {
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// open control socket
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// Open control socket.
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var fd int
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fd, err := unix.Socket(
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unix.AF_INET,
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unix.SOCK_DGRAM,
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0,
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)
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if err != nil {
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return err
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}
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defer unix.Close(fd)
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// do ioctl call
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var ifr [32]byte
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copy(ifr[:], name)
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_, _, errno := unix.Syscall(
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@ -216,7 +238,6 @@ func tunDestroy(name string) error {
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uintptr(unix.SIOCIFDESTROY),
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uintptr(unsafe.Pointer(&ifr[0])),
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)
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if errno != 0 {
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return fmt.Errorf("failed to destroy interface %s: %s", name, errno.Error())
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}
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@ -263,33 +284,71 @@ func CreateTUN(name string, mtu int) (TUNDevice, error) {
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})
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if errno != 0 {
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return nil, fmt.Errorf("error %s", errno.Error())
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tunFile.Close()
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tunDestroy(assignedName)
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return nil, fmt.Errorf("Unable to put into IFHEAD mode: %v", errno)
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}
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// Rename tun interface
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// Open control socket
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// Open control sockets
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confd, err := unix.Socket(
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unix.AF_INET,
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unix.SOCK_DGRAM,
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0,
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)
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if err != nil {
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tunFile.Close()
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tunDestroy(assignedName)
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return nil, err
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}
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defer unix.Close(confd)
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confd6, err := unix.Socket(
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unix.AF_INET6,
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unix.SOCK_DGRAM,
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0,
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)
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if err != nil {
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tunFile.Close()
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tunDestroy(assignedName)
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return nil, err
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}
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defer unix.Close(confd6)
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// set up struct for iface rename
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// Disable link-local v6, not just because WireGuard doesn't do that anyway, but
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// also because there are serious races with attaching and detaching LLv6 addresses
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// in relation to interface lifetime within the FreeBSD kernel.
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var ndireq in6_ndireq
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copy(ndireq.Name[:], assignedName)
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_, _, errno = unix.Syscall(
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unix.SYS_IOCTL,
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uintptr(confd6),
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uintptr(SIOCGIFINFO_IN6),
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uintptr(unsafe.Pointer(&ndireq)),
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)
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if errno != 0 {
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tunFile.Close()
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tunDestroy(assignedName)
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return nil, fmt.Errorf("Unable to get nd6 flags for %s: %v", assignedName, errno)
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}
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ndireq.Flags = ndireq.Flags &^ ND6_IFF_AUTO_LINKLOCAL
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ndireq.Flags = ndireq.Flags | ND6_IFF_NO_DAD
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_, _, errno = unix.Syscall(
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unix.SYS_IOCTL,
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uintptr(confd6),
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uintptr(SIOCSIFINFO_IN6),
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uintptr(unsafe.Pointer(&ndireq)),
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)
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if errno != 0 {
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tunFile.Close()
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tunDestroy(assignedName)
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return nil, fmt.Errorf("Unable to set nd6 flags for %s: %v", assignedName, errno)
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}
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// Rename the interface
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var newnp [unix.IFNAMSIZ]byte
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copy(newnp[:], name)
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var ifr ifreq_ptr
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copy(ifr.Name[:], assignedName)
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ifr.Data = uintptr(unsafe.Pointer(&newnp[0]))
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//do actual ioctl to rename iface
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_, _, errno = unix.Syscall(
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unix.SYS_IOCTL,
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uintptr(confd),
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@ -298,8 +357,8 @@ func CreateTUN(name string, mtu int) (TUNDevice, error) {
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)
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if errno != 0 {
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tunFile.Close()
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tunDestroy(name)
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return nil, fmt.Errorf("failed to rename %s to %s: %s", assignedName, name, errno.Error())
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tunDestroy(assignedName)
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return nil, fmt.Errorf("Failed to rename %s to %s: %v", assignedName, name, errno)
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}
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return CreateTUNFromFile(tunFile, mtu)
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