Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Daniel Borkmann says:

====================
pull-request: bpf-next 2020-08-04

The following pull-request contains BPF updates for your *net-next* tree.

We've added 73 non-merge commits during the last 9 day(s) which contain
a total of 135 files changed, 4603 insertions(+), 1013 deletions(-).

The main changes are:

1) Implement bpf_link support for XDP. Also add LINK_DETACH operation for the BPF
   syscall allowing processes with BPF link FD to force-detach, from Andrii Nakryiko.

2) Add BPF iterator for map elements and to iterate all BPF programs for efficient
   in-kernel inspection, from Yonghong Song and Alexei Starovoitov.

3) Separate bpf_get_{stack,stackid}() helpers for perf events in BPF to avoid
   unwinder errors, from Song Liu.

4) Allow cgroup local storage map to be shared between programs on the same
   cgroup. Also extend BPF selftests with coverage, from YiFei Zhu.

5) Add BPF exception tables to ARM64 JIT in order to be able to JIT BPF_PROBE_MEM
   load instructions, from Jean-Philippe Brucker.

6) Follow-up fixes on BPF socket lookup in combination with reuseport group
   handling. Also add related BPF selftests, from Jakub Sitnicki.

7) Allow to use socket storage in BPF_PROG_TYPE_CGROUP_SOCK-typed programs for
   socket create/release as well as bind functions, from Stanislav Fomichev.

8) Fix an info leak in xsk_getsockopt() when retrieving XDP stats via old struct
   xdp_statistics, from Peilin Ye.

9) Fix PT_REGS_RC{,_CORE}() macros in libbpf for MIPS arch, from Jerry Crunchtime.

10) Extend BPF kernel test infra with skb->family and skb->{local,remote}_ip{4,6}
    fields and allow user space to specify skb->dev via ifindex, from Dmitry Yakunin.

11) Fix a bpftool segfault due to missing program type name and make it more robust
    to prevent them in future gaps, from Quentin Monnet.

12) Consolidate cgroup helper functions across selftests and fix a v6 localhost
    resolver issue, from John Fastabend.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 405 insertions, 134 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index f7ef0f5c5569..7df6c9617321 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5467,10 +5467,6 @@ static int generic_xdp_install(struct net_device *dev, struct netdev_bpf *xdp)
 		}
 		break;
 
-	case XDP_QUERY_PROG:
-		xdp->prog_id = old ? old->aux->id : 0;
-		break;
-
 	default:
 		ret = -EINVAL;
 		break;
@@ -8740,189 +8736,464 @@ void dev_change_proto_down_reason(struct net_device *dev, unsigned long mask,
 }
 EXPORT_SYMBOL(dev_change_proto_down_reason);
 
-u32 __dev_xdp_query(struct net_device *dev, bpf_op_t bpf_op,
-		    enum bpf_netdev_command cmd)
+struct bpf_xdp_link {
+	struct bpf_link link;
+	struct net_device *dev; /* protected by rtnl_lock, no refcnt held */
+	int flags;
+};
+
+static enum bpf_xdp_mode dev_xdp_mode(u32 flags)
 {
-	struct netdev_bpf xdp;
+	if (flags & XDP_FLAGS_HW_MODE)
+		return XDP_MODE_HW;
+	if (flags & XDP_FLAGS_DRV_MODE)
+		return XDP_MODE_DRV;
+	return XDP_MODE_SKB;
+}
 
-	if (!bpf_op)
-		return 0;
+static bpf_op_t dev_xdp_bpf_op(struct net_device *dev, enum bpf_xdp_mode mode)
+{
+	switch (mode) {
+	case XDP_MODE_SKB:
+		return generic_xdp_install;
+	case XDP_MODE_DRV:
+	case XDP_MODE_HW:
+		return dev->netdev_ops->ndo_bpf;
+	default:
+		return NULL;
+	};
+}
 
-	memset(&xdp, 0, sizeof(xdp));
-	xdp.command = cmd;
+static struct bpf_xdp_link *dev_xdp_link(struct net_device *dev,
+					 enum bpf_xdp_mode mode)
+{
+	return dev->xdp_state[mode].link;
+}
+
+static struct bpf_prog *dev_xdp_prog(struct net_device *dev,
+				     enum bpf_xdp_mode mode)
+{
+	struct bpf_xdp_link *link = dev_xdp_link(dev, mode);
+
+	if (link)
+		return link->link.prog;
+	return dev->xdp_state[mode].prog;
+}
+
+u32 dev_xdp_prog_id(struct net_device *dev, enum bpf_xdp_mode mode)
+{
+	struct bpf_prog *prog = dev_xdp_prog(dev, mode);
 
-	/* Query must always succeed. */
-	WARN_ON(bpf_op(dev, &xdp) < 0 && cmd == XDP_QUERY_PROG);
+	return prog ? prog->aux->id : 0;
+}
 
-	return xdp.prog_id;
+static void dev_xdp_set_link(struct net_device *dev, enum bpf_xdp_mode mode,
+			     struct bpf_xdp_link *link)
+{
+	dev->xdp_state[mode].link = link;
+	dev->xdp_state[mode].prog = NULL;
 }
 
-static int dev_xdp_install(struct net_device *dev, bpf_op_t bpf_op,
-			   struct netlink_ext_ack *extack, u32 flags,
-			   struct bpf_prog *prog)
+static void dev_xdp_set_prog(struct net_device *dev, enum bpf_xdp_mode mode,
+			     struct bpf_prog *prog)
+{
+	dev->xdp_state[mode].link = NULL;
+	dev->xdp_state[mode].prog = prog;
+}
+
+static int dev_xdp_install(struct net_device *dev, enum bpf_xdp_mode mode,
+			   bpf_op_t bpf_op, struct netlink_ext_ack *extack,
+			   u32 flags, struct bpf_prog *prog)
 {
-	bool non_hw = !(flags & XDP_FLAGS_HW_MODE);
-	struct bpf_prog *prev_prog = NULL;
 	struct netdev_bpf xdp;
 	int err;
 
-	if (non_hw) {
-		prev_prog = bpf_prog_by_id(__dev_xdp_query(dev, bpf_op,
-							   XDP_QUERY_PROG));
-		if (IS_ERR(prev_prog))
-			prev_prog = NULL;
-	}
-
 	memset(&xdp, 0, sizeof(xdp));
-	if (flags & XDP_FLAGS_HW_MODE)
-		xdp.command = XDP_SETUP_PROG_HW;
-	else
-		xdp.command = XDP_SETUP_PROG;
+	xdp.command = mode == XDP_MODE_HW ? XDP_SETUP_PROG_HW : XDP_SETUP_PROG;
 	xdp.extack = extack;
 	xdp.flags = flags;
 	xdp.prog = prog;
 
+	/* Drivers assume refcnt is already incremented (i.e, prog pointer is
+	 * "moved" into driver), so they don't increment it on their own, but
+	 * they do decrement refcnt when program is detached or replaced.
+	 * Given net_device also owns link/prog, we need to bump refcnt here
+	 * to prevent drivers from underflowing it.
+	 */
+	if (prog)
+		bpf_prog_inc(prog);
 	err = bpf_op(dev, &xdp);
-	if (!err && non_hw)
-		bpf_prog_change_xdp(prev_prog, prog);
+	if (err) {
+		if (prog)
+			bpf_prog_put(prog);
+		return err;
+	}
 
-	if (prev_prog)
-		bpf_prog_put(prev_prog);
+	if (mode != XDP_MODE_HW)
+		bpf_prog_change_xdp(dev_xdp_prog(dev, mode), prog);
 
-	return err;
+	return 0;
 }
 
 static void dev_xdp_uninstall(struct net_device *dev)
 {
-	struct netdev_bpf xdp;
-	bpf_op_t ndo_bpf;
+	struct bpf_xdp_link *link;
+	struct bpf_prog *prog;
+	enum bpf_xdp_mode mode;
+	bpf_op_t bpf_op;
 
-	/* Remove generic XDP */
-	WARN_ON(dev_xdp_install(dev, generic_xdp_install, NULL, 0, NULL));
+	ASSERT_RTNL();
 
-	/* Remove from the driver */
-	ndo_bpf = dev->netdev_ops->ndo_bpf;
-	if (!ndo_bpf)
-		return;
+	for (mode = XDP_MODE_SKB; mode < __MAX_XDP_MODE; mode++) {
+		prog = dev_xdp_prog(dev, mode);
+		if (!prog)
+			continue;
 
-	memset(&xdp, 0, sizeof(xdp));
-	xdp.command = XDP_QUERY_PROG;
-	WARN_ON(ndo_bpf(dev, &xdp));
-	if (xdp.prog_id)
-		WARN_ON(dev_xdp_install(dev, ndo_bpf, NULL, xdp.prog_flags,
-					NULL));
+		bpf_op = dev_xdp_bpf_op(dev, mode);
+		if (!bpf_op)
+			continue;
 
-	/* Remove HW offload */
-	memset(&xdp, 0, sizeof(xdp));
-	xdp.command = XDP_QUERY_PROG_HW;
-	if (!ndo_bpf(dev, &xdp) && xdp.prog_id)
-		WARN_ON(dev_xdp_install(dev, ndo_bpf, NULL, xdp.prog_flags,
-					NULL));
+		WARN_ON(dev_xdp_install(dev, mode, bpf_op, NULL, 0, NULL));
+
+		/* auto-detach link from net device */
+		link = dev_xdp_link(dev, mode);
+		if (link)
+			link->dev = NULL;
+		else
+			bpf_prog_put(prog);
+
+		dev_xdp_set_link(dev, mode, NULL);
+	}
 }
 
-/**
- *	dev_change_xdp_fd - set or clear a bpf program for a device rx path
- *	@dev: device
- *	@extack: netlink extended ack
- *	@fd: new program fd or negative value to clear
- *	@expected_fd: old program fd that userspace expects to replace or clear
- *	@flags: xdp-related flags
- *
- *	Set or clear a bpf program for a device
- */
-int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
-		      int fd, int expected_fd, u32 flags)
+static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack,
+			  struct bpf_xdp_link *link, struct bpf_prog *new_prog,
+			  struct bpf_prog *old_prog, u32 flags)
 {
-	const struct net_device_ops *ops = dev->netdev_ops;
-	enum bpf_netdev_command query;
-	u32 prog_id, expected_id = 0;
-	bpf_op_t bpf_op, bpf_chk;
-	struct bpf_prog *prog;
-	bool offload;
+	struct bpf_prog *cur_prog;
+	enum bpf_xdp_mode mode;
+	bpf_op_t bpf_op;
 	int err;
 
 	ASSERT_RTNL();
 
-	offload = flags & XDP_FLAGS_HW_MODE;
-	query = offload ? XDP_QUERY_PROG_HW : XDP_QUERY_PROG;
+	/* either link or prog attachment, never both */
+	if (link && (new_prog || old_prog))
+		return -EINVAL;
+	/* link supports only XDP mode flags */
+	if (link && (flags & ~XDP_FLAGS_MODES)) {
+		NL_SET_ERR_MSG(extack, "Invalid XDP flags for BPF link attachment");
+		return -EINVAL;
+	}
+	/* just one XDP mode bit should be set, zero defaults to SKB mode */
+	if (hweight32(flags & XDP_FLAGS_MODES) > 1) {
+		NL_SET_ERR_MSG(extack, "Only one XDP mode flag can be set");
+		return -EINVAL;
+	}
+	/* old_prog != NULL implies XDP_FLAGS_REPLACE is set */
+	if (old_prog && !(flags & XDP_FLAGS_REPLACE)) {
+		NL_SET_ERR_MSG(extack, "XDP_FLAGS_REPLACE is not specified");
+		return -EINVAL;
+	}
 
-	bpf_op = bpf_chk = ops->ndo_bpf;
-	if (!bpf_op && (flags & (XDP_FLAGS_DRV_MODE | XDP_FLAGS_HW_MODE))) {
-		NL_SET_ERR_MSG(extack, "underlying driver does not support XDP in native mode");
-		return -EOPNOTSUPP;
+	mode = dev_xdp_mode(flags);
+	/* can't replace attached link */
+	if (dev_xdp_link(dev, mode)) {
+		NL_SET_ERR_MSG(extack, "Can't replace active BPF XDP link");
+		return -EBUSY;
 	}
-	if (!bpf_op || (flags & XDP_FLAGS_SKB_MODE))
-		bpf_op = generic_xdp_install;
-	if (bpf_op == bpf_chk)
-		bpf_chk = generic_xdp_install;
-
-	prog_id = __dev_xdp_query(dev, bpf_op, query);
-	if (flags & XDP_FLAGS_REPLACE) {
-		if (expected_fd >= 0) {
-			prog = bpf_prog_get_type_dev(expected_fd,
-						     BPF_PROG_TYPE_XDP,
-						     bpf_op == ops->ndo_bpf);
-			if (IS_ERR(prog))
-				return PTR_ERR(prog);
-			expected_id = prog->aux->id;
-			bpf_prog_put(prog);
-		}
 
-		if (prog_id != expected_id) {
-			NL_SET_ERR_MSG(extack, "Active program does not match expected");
-			return -EEXIST;
-		}
+	cur_prog = dev_xdp_prog(dev, mode);
+	/* can't replace attached prog with link */
+	if (link && cur_prog) {
+		NL_SET_ERR_MSG(extack, "Can't replace active XDP program with BPF link");
+		return -EBUSY;
+	}
+	if ((flags & XDP_FLAGS_REPLACE) && cur_prog != old_prog) {
+		NL_SET_ERR_MSG(extack, "Active program does not match expected");
+		return -EEXIST;
+	}
+	if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && cur_prog) {
+		NL_SET_ERR_MSG(extack, "XDP program already attached");
+		return -EBUSY;
 	}
-	if (fd >= 0) {
-		if (!offload && __dev_xdp_query(dev, bpf_chk, XDP_QUERY_PROG)) {
-			NL_SET_ERR_MSG(extack, "native and generic XDP can't be active at the same time");
-			return -EEXIST;
-		}
 
-		if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && prog_id) {
-			NL_SET_ERR_MSG(extack, "XDP program already attached");
-			return -EBUSY;
-		}
+	/* put effective new program into new_prog */
+	if (link)
+		new_prog = link->link.prog;
 
-		prog = bpf_prog_get_type_dev(fd, BPF_PROG_TYPE_XDP,
-					     bpf_op == ops->ndo_bpf);
-		if (IS_ERR(prog))
-			return PTR_ERR(prog);
+	if (new_prog) {
+		bool offload = mode == XDP_MODE_HW;
+		enum bpf_xdp_mode other_mode = mode == XDP_MODE_SKB
+					       ? XDP_MODE_DRV : XDP_MODE_SKB;
 
-		if (!offload && bpf_prog_is_dev_bound(prog->aux)) {
-			NL_SET_ERR_MSG(extack, "using device-bound program without HW_MODE flag is not supported");
-			bpf_prog_put(prog);
+		if (!offload && dev_xdp_prog(dev, other_mode)) {
+			NL_SET_ERR_MSG(extack, "Native and generic XDP can't be active at the same time");
+			return -EEXIST;
+		}
+		if (!offload && bpf_prog_is_dev_bound(new_prog->aux)) {
+			NL_SET_ERR_MSG(extack, "Using device-bound program without HW_MODE flag is not supported");
 			return -EINVAL;
 		}
-
-		if (prog->expected_attach_type == BPF_XDP_DEVMAP) {
+		if (new_prog->expected_attach_type == BPF_XDP_DEVMAP) {
 			NL_SET_ERR_MSG(extack, "BPF_XDP_DEVMAP programs can not be attached to a device");
-			bpf_prog_put(prog);
 			return -EINVAL;
 		}
-
-		if (prog->expected_attach_type == BPF_XDP_CPUMAP) {
-			NL_SET_ERR_MSG(extack,
-				       "BPF_XDP_CPUMAP programs can not be attached to a device");
-			bpf_prog_put(prog);
+		if (new_prog->expected_attach_type == BPF_XDP_CPUMAP) {
+			NL_SET_ERR_MSG(extack, "BPF_XDP_CPUMAP programs can not be attached to a device");
 			return -EINVAL;
 		}
+	}
 
-		/* prog->aux->id may be 0 for orphaned device-bound progs */
-		if (prog->aux->id && prog->aux->id == prog_id) {
-			bpf_prog_put(prog);
-			return 0;
+	/* don't call drivers if the effective program didn't change */
+	if (new_prog != cur_prog) {
+		bpf_op = dev_xdp_bpf_op(dev, mode);
+		if (!bpf_op) {
+			NL_SET_ERR_MSG(extack, "Underlying driver does not support XDP in native mode");
+			return -EOPNOTSUPP;
+		}
+
+		err = dev_xdp_install(dev, mode, bpf_op, extack, flags, new_prog);
+		if (err)
+			return err;
+	}
+
+	if (link)
+		dev_xdp_set_link(dev, mode, link);
+	else
+		dev_xdp_set_prog(dev, mode, new_prog);
+	if (cur_prog)
+		bpf_prog_put(cur_prog);
+
+	return 0;
+}
+
+static int dev_xdp_attach_link(struct net_device *dev,
+			       struct netlink_ext_ack *extack,
+			       struct bpf_xdp_link *link)
+{
+	return dev_xdp_attach(dev, extack, link, NULL, NULL, link->flags);
+}
+
+static int dev_xdp_detach_link(struct net_device *dev,
+			       struct netlink_ext_ack *extack,
+			       struct bpf_xdp_link *link)
+{
+	enum bpf_xdp_mode mode;
+	bpf_op_t bpf_op;
+
+	ASSERT_RTNL();
+
+	mode = dev_xdp_mode(link->flags);
+	if (dev_xdp_link(dev, mode) != link)
+		return -EINVAL;
+
+	bpf_op = dev_xdp_bpf_op(dev, mode);
+	WARN_ON(dev_xdp_install(dev, mode, bpf_op, NULL, 0, NULL));
+	dev_xdp_set_link(dev, mode, NULL);
+	return 0;
+}
+
+static void bpf_xdp_link_release(struct bpf_link *link)
+{
+	struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
+
+	rtnl_lock();
+
+	/* if racing with net_device's tear down, xdp_link->dev might be
+	 * already NULL, in which case link was already auto-detached
+	 */
+	if (xdp_link->dev) {
+		WARN_ON(dev_xdp_detach_link(xdp_link->dev, NULL, xdp_link));
+		xdp_link->dev = NULL;
+	}
+
+	rtnl_unlock();
+}
+
+static int bpf_xdp_link_detach(struct bpf_link *link)
+{
+	bpf_xdp_link_release(link);
+	return 0;
+}
+
+static void bpf_xdp_link_dealloc(struct bpf_link *link)
+{
+	struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
+
+	kfree(xdp_link);
+}
+
+static void bpf_xdp_link_show_fdinfo(const struct bpf_link *link,
+				     struct seq_file *seq)
+{
+	struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
+	u32 ifindex = 0;
+
+	rtnl_lock();
+	if (xdp_link->dev)
+		ifindex = xdp_link->dev->ifindex;
+	rtnl_unlock();
+
+	seq_printf(seq, "ifindex:\t%u\n", ifindex);
+}
+
+static int bpf_xdp_link_fill_link_info(const struct bpf_link *link,
+				       struct bpf_link_info *info)
+{
+	struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
+	u32 ifindex = 0;
+
+	rtnl_lock();
+	if (xdp_link->dev)
+		ifindex = xdp_link->dev->ifindex;
+	rtnl_unlock();
+
+	info->xdp.ifindex = ifindex;
+	return 0;
+}
+
+static int bpf_xdp_link_update(struct bpf_link *link, struct bpf_prog *new_prog,
+			       struct bpf_prog *old_prog)
+{
+	struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
+	enum bpf_xdp_mode mode;
+	bpf_op_t bpf_op;
+	int err = 0;
+
+	rtnl_lock();
+
+	/* link might have been auto-released already, so fail */
+	if (!xdp_link->dev) {
+		err = -ENOLINK;
+		goto out_unlock;
+	}
+
+	if (old_prog && link->prog != old_prog) {
+		err = -EPERM;
+		goto out_unlock;
+	}
+	old_prog = link->prog;
+	if (old_prog == new_prog) {
+		/* no-op, don't disturb drivers */
+		bpf_prog_put(new_prog);
+		goto out_unlock;
+	}
+
+	mode = dev_xdp_mode(xdp_link->flags);
+	bpf_op = dev_xdp_bpf_op(xdp_link->dev, mode);
+	err = dev_xdp_install(xdp_link->dev, mode, bpf_op, NULL,
+			      xdp_link->flags, new_prog);
+	if (err)
+		goto out_unlock;
+
+	old_prog = xchg(&link->prog, new_prog);
+	bpf_prog_put(old_prog);
+
+out_unlock:
+	rtnl_unlock();
+	return err;
+}
+
+static const struct bpf_link_ops bpf_xdp_link_lops = {
+	.release = bpf_xdp_link_release,
+	.dealloc = bpf_xdp_link_dealloc,
+	.detach = bpf_xdp_link_detach,
+	.show_fdinfo = bpf_xdp_link_show_fdinfo,
+	.fill_link_info = bpf_xdp_link_fill_link_info,
+	.update_prog = bpf_xdp_link_update,
+};
+
+int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
+{
+	struct net *net = current->nsproxy->net_ns;
+	struct bpf_link_primer link_primer;
+	struct bpf_xdp_link *link;
+	struct net_device *dev;
+	int err, fd;
+
+	dev = dev_get_by_index(net, attr->link_create.target_ifindex);
+	if (!dev)
+		return -EINVAL;
+
+	link = kzalloc(sizeof(*link), GFP_USER);
+	if (!link) {
+		err = -ENOMEM;
+		goto out_put_dev;
+	}
+
+	bpf_link_init(&link->link, BPF_LINK_TYPE_XDP, &bpf_xdp_link_lops, prog);
+	link->dev = dev;
+	link->flags = attr->link_create.flags;
+
+	err = bpf_link_prime(&link->link, &link_primer);
+	if (err) {
+		kfree(link);
+		goto out_put_dev;
+	}
+
+	rtnl_lock();
+	err = dev_xdp_attach_link(dev, NULL, link);
+	rtnl_unlock();
+
+	if (err) {
+		bpf_link_cleanup(&link_primer);
+		goto out_put_dev;
+	}
+
+	fd = bpf_link_settle(&link_primer);
+	/* link itself doesn't hold dev's refcnt to not complicate shutdown */
+	dev_put(dev);
+	return fd;
+
+out_put_dev:
+	dev_put(dev);
+	return err;
+}
+
+/**
+ *	dev_change_xdp_fd - set or clear a bpf program for a device rx path
+ *	@dev: device
+ *	@extack: netlink extended ack
+ *	@fd: new program fd or negative value to clear
+ *	@expected_fd: old program fd that userspace expects to replace or clear
+ *	@flags: xdp-related flags
+ *
+ *	Set or clear a bpf program for a device
+ */
+int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
+		      int fd, int expected_fd, u32 flags)
+{
+	enum bpf_xdp_mode mode = dev_xdp_mode(flags);
+	struct bpf_prog *new_prog = NULL, *old_prog = NULL;
+	int err;
+
+	ASSERT_RTNL();
+
+	if (fd >= 0) {
+		new_prog = bpf_prog_get_type_dev(fd, BPF_PROG_TYPE_XDP,
+						 mode != XDP_MODE_SKB);
+		if (IS_ERR(new_prog))
+			return PTR_ERR(new_prog);
+	}
+
+	if (expected_fd >= 0) {
+		old_prog = bpf_prog_get_type_dev(expected_fd, BPF_PROG_TYPE_XDP,
+						 mode != XDP_MODE_SKB);
+		if (IS_ERR(old_prog)) {
+			err = PTR_ERR(old_prog);
+			old_prog = NULL;
+			goto err_out;
 		}
-	} else {
-		if (!prog_id)
-			return 0;
-		prog = NULL;
 	}
 
-	err = dev_xdp_install(dev, bpf_op, extack, flags, prog);
-	if (err < 0 && prog)
-		bpf_prog_put(prog);
+	err = dev_xdp_attach(dev, extack, NULL, new_prog, old_prog, flags);
 
+err_out:
+	if (err && new_prog)
+		bpf_prog_put(new_prog);
+	if (old_prog)
+		bpf_prog_put(old_prog);
 	return err;
 }