diff options
Diffstat (limited to 'pkg')
| -rw-r--r-- | pkg/abi/linux/netlink_route.go | 13 | ||||
| -rw-r--r-- | pkg/sentry/socket/netlink/route/protocol.go | 158 |
2 files changed, 158 insertions, 13 deletions
diff --git a/pkg/abi/linux/netlink_route.go b/pkg/abi/linux/netlink_route.go index 0e3582ab6..40bec566c 100644 --- a/pkg/abi/linux/netlink_route.go +++ b/pkg/abi/linux/netlink_route.go @@ -205,6 +205,9 @@ type RouteMessage struct { Flags uint32 } +// SizeOfRouteMessage is the size of RouteMessage. +const SizeOfRouteMessage = 12 + // Route types, from uapi/linux/rtnetlink.h. const ( // RTN_UNSPEC represents an unspecified route type. @@ -331,3 +334,13 @@ const ( RTF_GATEWAY = 0x2 RTF_UP = 0x1 ) + +// RtAttr is the header of optional addition route information, as a netlink +// attribute. From include/uapi/linux/rtnetlink.h. +type RtAttr struct { + Len uint16 + Type uint16 +} + +// SizeOfRtAttr is the size of RtAttr. +const SizeOfRtAttr = 4 diff --git a/pkg/sentry/socket/netlink/route/protocol.go b/pkg/sentry/socket/netlink/route/protocol.go index 80a15d6cb..2b3c7f5b3 100644 --- a/pkg/sentry/socket/netlink/route/protocol.go +++ b/pkg/sentry/socket/netlink/route/protocol.go @@ -19,12 +19,14 @@ import ( "bytes" "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/binary" "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/sentry/inet" "gvisor.dev/gvisor/pkg/sentry/kernel" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/sentry/socket/netlink" "gvisor.dev/gvisor/pkg/syserr" + "gvisor.dev/gvisor/pkg/usermem" ) // commandKind describes the operational class of a message type. @@ -66,8 +68,14 @@ func (p *Protocol) CanSend() bool { return true } -// dumpLinks handles RTM_GETLINK + NLM_F_DUMP requests. +// dumpLinks handles RTM_GETLINK dump requests. func (p *Protocol) dumpLinks(ctx context.Context, hdr linux.NetlinkMessageHeader, data []byte, ms *netlink.MessageSet) *syserr.Error { + // TODO(b/68878065): Only the dump variant of the types below are + // supported. + if hdr.Flags&linux.NLM_F_DUMP != linux.NLM_F_DUMP { + return syserr.ErrNotSupported + } + // NLM_F_DUMP + RTM_GETLINK messages are supposed to include an // ifinfomsg. However, Linux <3.9 only checked for rtgenmsg, and some // userspace applications (including glibc) still include rtgenmsg. @@ -121,8 +129,14 @@ func (p *Protocol) dumpLinks(ctx context.Context, hdr linux.NetlinkMessageHeader return nil } -// dumpAddrs handles RTM_GETADDR + NLM_F_DUMP requests. +// dumpAddrs handles RTM_GETADDR dump requests. func (p *Protocol) dumpAddrs(ctx context.Context, hdr linux.NetlinkMessageHeader, data []byte, ms *netlink.MessageSet) *syserr.Error { + // TODO(b/68878065): Only the dump variant of the types below are + // supported. + if hdr.Flags&linux.NLM_F_DUMP != linux.NLM_F_DUMP { + return syserr.ErrNotSupported + } + // RTM_GETADDR dump requests need not contain anything more than the // netlink header and 1 byte protocol family common to all // NETLINK_ROUTE requests. @@ -163,22 +177,146 @@ func (p *Protocol) dumpAddrs(ctx context.Context, hdr linux.NetlinkMessageHeader return nil } -// dumpRoutes handles RTM_GETROUTE + NLM_F_DUMP requests. +// commonPrefixLen reports the length of the longest IP address prefix. +// This is a simplied version from Golang's src/net/addrselect.go. +func commonPrefixLen(a, b []byte) (cpl int) { + for len(a) > 0 { + if a[0] == b[0] { + cpl += 8 + a = a[1:] + b = b[1:] + continue + } + bits := 8 + ab, bb := a[0], b[0] + for { + ab >>= 1 + bb >>= 1 + bits-- + if ab == bb { + cpl += bits + return + } + } + } + return +} + +// fillRoute returns the Route using LPM algorithm. Refer to Linux's +// net/ipv4/route.c:rt_fill_info(). +func fillRoute(routes []inet.Route, addr []byte) (inet.Route, *syserr.Error) { + family := uint8(linux.AF_INET) + if len(addr) != 4 { + family = linux.AF_INET6 + } + + idx := -1 // Index of the Route rule to be returned. + idxDef := -1 // Index of the default route rule. + prefix := 0 // Current longest prefix. + for i, route := range routes { + if route.Family != family { + continue + } + + if len(route.GatewayAddr) > 0 && route.DstLen == 0 { + idxDef = i + continue + } + + cpl := commonPrefixLen(addr, route.DstAddr) + if cpl < int(route.DstLen) { + continue + } + cpl = int(route.DstLen) + if cpl > prefix { + idx = i + prefix = cpl + } + } + if idx == -1 { + idx = idxDef + } + if idx == -1 { + return inet.Route{}, syserr.ErrNoRoute + } + + route := routes[idx] + if family == linux.AF_INET { + route.DstLen = 32 + } else { + route.DstLen = 128 + } + route.DstAddr = addr + route.Flags |= linux.RTM_F_CLONED // This route is cloned. + return route, nil +} + +// parseForDestination parses a message as format of RouteMessage-RtAttr-dst. +func parseForDestination(data []byte) ([]byte, *syserr.Error) { + var rtMsg linux.RouteMessage + if len(data) < linux.SizeOfRouteMessage { + return nil, syserr.ErrInvalidArgument + } + binary.Unmarshal(data[:linux.SizeOfRouteMessage], usermem.ByteOrder, &rtMsg) + // iproute2 added the RTM_F_LOOKUP_TABLE flag in version v4.4.0. See + // commit bc234301af12. Note we don't check this flag for backward + // compatibility. + if rtMsg.Flags != 0 && rtMsg.Flags != linux.RTM_F_LOOKUP_TABLE { + return nil, syserr.ErrNotSupported + } + + data = data[linux.SizeOfRouteMessage:] + + // TODO(gvisor.dev/issue/1611): Add generic attribute parsing. + var rtAttr linux.RtAttr + if len(data) < linux.SizeOfRtAttr { + return nil, syserr.ErrInvalidArgument + } + binary.Unmarshal(data[:linux.SizeOfRtAttr], usermem.ByteOrder, &rtAttr) + if rtAttr.Type != linux.RTA_DST { + return nil, syserr.ErrInvalidArgument + } + + if len(data) < int(rtAttr.Len) { + return nil, syserr.ErrInvalidArgument + } + return data[linux.SizeOfRtAttr:rtAttr.Len], nil +} + +// dumpRoutes handles RTM_GETROUTE requests. func (p *Protocol) dumpRoutes(ctx context.Context, hdr linux.NetlinkMessageHeader, data []byte, ms *netlink.MessageSet) *syserr.Error { // RTM_GETROUTE dump requests need not contain anything more than the // netlink header and 1 byte protocol family common to all // NETLINK_ROUTE requests. - // We always send back an NLMSG_DONE. - ms.Multi = true - stack := inet.StackFromContext(ctx) if stack == nil { // No network routes. return nil } - for _, rt := range stack.RouteTable() { + routeTables := stack.RouteTable() + + if hdr.Flags == linux.NLM_F_REQUEST { + dst, err := parseForDestination(data) + if err != nil { + return err + } + route, err := fillRoute(routeTables, dst) + if err != nil { + // TODO(gvisor.dev/issue/1237): return NLMSG_ERROR with ENETUNREACH. + return syserr.ErrNotSupported + } + routeTables = append([]inet.Route{}, route) + } else if hdr.Flags&linux.NLM_F_DUMP == linux.NLM_F_DUMP { + // We always send back an NLMSG_DONE. + ms.Multi = true + } else { + // TODO(b/68878065): Only above cases are supported. + return syserr.ErrNotSupported + } + + for _, rt := range routeTables { m := ms.AddMessage(linux.NetlinkMessageHeader{ Type: linux.RTM_NEWROUTE, }) @@ -236,12 +374,6 @@ func (p *Protocol) ProcessMessage(ctx context.Context, hdr linux.NetlinkMessageH } } - // TODO(b/68878065): Only the dump variant of the types below are - // supported. - if hdr.Flags&linux.NLM_F_DUMP != linux.NLM_F_DUMP { - return syserr.ErrNotSupported - } - switch hdr.Type { case linux.RTM_GETLINK: return p.dumpLinks(ctx, hdr, data, ms) |