Implement IFLA_IFNAME which specifies an interface's name.

IFLA_IFNAME is used to set an interface's name when being used
with RTM_NEWLINK and RTM_SETLINK. RTM_NEWLINK is the preferred way, it
is backwards compatible with RTM_SETLINK. For gVisor, when RTM_SETLINK is
introduced, it shall just share the implementation.

PiperOrigin-RevId: 647833657

pkg/sentry/socket/netstack/stack.go

@@ -123,15 +123,13 @@ func (s *Stack) SetInterface(ctx context.Context, msg *nlmsg.Message) *syserr.Er
 			if len(value) < 1 {
 				return syserr.ErrInvalidArgument
 			}
-			if ifinfomsg.Index != 0 {
-				// Device name changing isn't supported yet.
-				return syserr.ErrNotSupported
-			}
-			ifname = value.String()
-			for idx, ifa := range s.Interfaces() {
-				if ifname == ifa.Name {
-					ifinfomsg.Index = idx
-					break
+			if ifinfomsg.Index == 0 {
+				ifname = value.String()
+				for idx, ifa := range s.Interfaces() {
+					if ifname == ifa.Name {
+						ifinfomsg.Index = idx
+						break
+					}
 				}
 			}
 		case linux.IFLA_MASTER:
@@ -190,6 +188,10 @@ func (s *Stack) setLink(id tcpip.NICID, linkAttrs map[uint16]nlmsg.BytesView) *s
 			if err := s.Stack.SetNICAddress(id, addr); err != nil {
 				return syserr.TranslateNetstackError(err)
 			}
+		case linux.IFLA_IFNAME:
+			if err := s.Stack.SetNICName(id, v.String()); err != nil {
+				return syserr.TranslateNetstackError(err)
+			}
 		}
 	}
 	return nil

pkg/tcpip/stack/stack.go

@@ -1057,6 +1057,19 @@ func (s *Stack) SetNICAddress(id tcpip.NICID, addr tcpip.LinkAddress) tcpip.Erro
 	return nil
 }
 
+// SetNICName sets a NIC's name.
+func (s *Stack) SetNICName(id tcpip.NICID, name string) tcpip.Error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	nic, ok := s.nics[id]
+	if !ok {
+		return &tcpip.ErrUnknownNICID{}
+	}
+	nic.name = name
+	return nil
+}
+
 // NICInfo captures the name and addresses assigned to a NIC.
 type NICInfo struct {
 	Name              string

test/rtnetlink/linux/veth_test.sh

@@ -30,6 +30,17 @@ if ! wait_for ! ip link show test_veth02; then
   exit 1
 fi
 
+# Create a new veth pair in the current namespace and rename the link.
+ip link add name test_veth01 type veth peer name test_veth02
+ip link set test_veth01 name test_veth03
+ip link show test_veth03
+ip link del name test_veth03
+# Check that test_veth02 has been destroyed.
+if ! wait_for ! ip link show test_veth02; then
+  fail "test_veth02 hasn't been destroyed"
+  exit 1
+fi
+
 ip netns add test
 ip link add test_veth01 type veth peer name test_veth02 netns test
 ip link show test_veth01

test/syscalls/linux/socket_netlink_route.cc

@@ -200,6 +200,64 @@ TEST(NetlinkRouteTest, GetLinkByIndex) {
   EXPECT_TRUE(found) << "Netlink response does not contain any links.";
 }
 
+TEST(NetlinkRouteTest, ChangeLinkName) {
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_ADMIN)));
+  SKIP_IF(IsRunningWithHostinet());
+  // Hosts that run with old kernel allow renaming only when
+  // the interface is down. The restriction has been removed.
+  SKIP_IF(!IsRunningOnGvisor());
+  Link loopback_link = ASSERT_NO_ERRNO_AND_VALUE(LoopbackLink());
+
+  FileDescriptor fd =
+      ASSERT_NO_ERRNO_AND_VALUE(NetlinkBoundSocket(NETLINK_ROUTE));
+
+  struct request {
+    struct nlmsghdr hdr;
+    struct ifinfomsg ifm;
+    struct rtattr rtattr;
+    char ifname[IFNAMSIZ];
+    char pad[NLMSG_ALIGNTO + RTA_ALIGNTO];
+  };
+
+  const std::string new_linkname = "notloopback";
+
+  // Change the link name.
+  struct request req = {};
+  req.hdr.nlmsg_len = sizeof(req);
+  req.hdr.nlmsg_type = RTM_NEWLINK;
+  req.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
+  req.hdr.nlmsg_seq = kSeq;
+  req.ifm.ifi_family = AF_UNSPEC;
+  req.ifm.ifi_index = loopback_link.index;
+  req.rtattr.rta_type = IFLA_IFNAME;
+  req.rtattr.rta_len = RTA_LENGTH(new_linkname.size() + 1);
+  strncpy(req.ifname, new_linkname.c_str(), sizeof(req.ifname));
+  req.hdr.nlmsg_len =
+      NLMSG_LENGTH(sizeof(req.ifm)) + NLMSG_ALIGN(req.rtattr.rta_len);
+  EXPECT_NO_ERRNO(NetlinkRequestAckOrError(fd, kSeq, &req, sizeof(req)));
+
+  // Search the link by the new name.
+  loopback_link.name = new_linkname;
+  req.hdr.nlmsg_type = RTM_GETLINK;
+  req.ifm.ifi_index = 0;
+  req.hdr.nlmsg_flags = NLM_F_REQUEST;
+  req.rtattr.rta_type = IFLA_IFNAME;
+  req.rtattr.rta_len = RTA_LENGTH(new_linkname.size() + 1);
+  strncpy(req.ifname, new_linkname.c_str(), sizeof(req.ifname));
+  req.hdr.nlmsg_len =
+      NLMSG_LENGTH(sizeof(req.ifm)) + NLMSG_ALIGN(req.rtattr.rta_len);
+
+  bool found = false;
+  ASSERT_NO_ERRNO(NetlinkRequestResponse(
+      fd, &req, sizeof(req),
+      [&](const struct nlmsghdr* hdr) {
+        CheckLinkMsg(hdr, loopback_link);
+        found = true;
+      },
+      false));
+  EXPECT_TRUE(found) << "Netlink response does not contain any links.";
+}
+
 TEST(NetlinkRouteTest, LinkUp) {
   SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_ADMIN)));
   SKIP_IF(IsRunningWithHostinet());