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

Pull networking updates from David Miller:
 "Highlights:

   1) Fix the iwlwifi regression, from Johannes Berg.

   2) Support BSS coloring and 802.11 encapsulation offloading in
      hardware, from John Crispin.

   3) Fix some potential Spectre issues in qtnfmac, from Sergey
      Matyukevich.

   4) Add TTL decrement action to openvswitch, from Matteo Croce.

   5) Allow paralleization through flow_action setup by not taking the
      RTNL mutex, from Vlad Buslov.

   6) A lot of zero-length array to flexible-array conversions, from
      Gustavo A. R. Silva.

   7) Align XDP statistics names across several drivers for consistency,
      from Lorenzo Bianconi.

   8) Add various pieces of infrastructure for offloading conntrack, and
      make use of it in mlx5 driver, from Paul Blakey.

   9) Allow using listening sockets in BPF sockmap, from Jakub Sitnicki.

  10) Lots of parallelization improvements during configuration changes
      in mlxsw driver, from Ido Schimmel.

  11) Add support to devlink for generic packet traps, which report
      packets dropped during ACL processing. And use them in mlxsw
      driver. From Jiri Pirko.

  12) Support bcmgenet on ACPI, from Jeremy Linton.

  13) Make BPF compatible with RT, from Thomas Gleixnet, Alexei
      Starovoitov, and your's truly.

  14) Support XDP meta-data in virtio_net, from Yuya Kusakabe.

  15) Fix sysfs permissions when network devices change namespaces, from
      Christian Brauner.

  16) Add a flags element to ethtool_ops so that drivers can more simply
      indicate which coalescing parameters they actually support, and
      therefore the generic layer can validate the user's ethtool
      request. Use this in all drivers, from Jakub Kicinski.

  17) Offload FIFO qdisc in mlxsw, from Petr Machata.

  18) Support UDP sockets in sockmap, from Lorenz Bauer.

  19) Fix stretch ACK bugs in several TCP congestion control modules,
      from Pengcheng Yang.

  20) Support virtual functiosn in octeontx2 driver, from Tomasz
      Duszynski.

  21) Add region operations for devlink and use it in ice driver to dump
      NVM contents, from Jacob Keller.

  22) Add support for hw offload of MACSEC, from Antoine Tenart.

  23) Add support for BPF programs that can be attached to LSM hooks,
      from KP Singh.

  24) Support for multiple paths, path managers, and counters in MPTCP.
      From Peter Krystad, Paolo Abeni, Florian Westphal, Davide Caratti,
      and others.

  25) More progress on adding the netlink interface to ethtool, from
      Michal Kubecek"

* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2121 commits)
  net: ipv6: rpl_iptunnel: Fix potential memory leak in rpl_do_srh_inline
  cxgb4/chcr: nic-tls stats in ethtool
  net: dsa: fix oops while probing Marvell DSA switches
  net/bpfilter: remove superfluous testing message
  net: macb: Fix handling of fixed-link node
  net: dsa: ksz: Select KSZ protocol tag
  netdevsim: dev: Fix memory leak in nsim_dev_take_snapshot_write
  net: stmmac: add EHL 2.5Gbps PCI info and PCI ID
  net: stmmac: add EHL PSE0 & PSE1 1Gbps PCI info and PCI ID
  net: stmmac: create dwmac-intel.c to contain all Intel platform
  net: dsa: bcm_sf2: Support specifying VLAN tag egress rule
  net: dsa: bcm_sf2: Add support for matching VLAN TCI
  net: dsa: bcm_sf2: Move writing of CFP_DATA(5) into slicing functions
  net: dsa: bcm_sf2: Check earlier for FLOW_EXT and FLOW_MAC_EXT
  net: dsa: bcm_sf2: Disable learning for ASP port
  net: dsa: b53: Deny enslaving port 7 for 7278 into a bridge
  net: dsa: b53: Prevent tagged VLAN on port 7 for 7278
  net: dsa: b53: Restore VLAN entries upon (re)configuration
  net: dsa: bcm_sf2: Fix overflow checks
  hv_netvsc: Remove unnecessary round_up for recv_completion_cnt
  ...

1 files changed, 387 insertions, 118 deletions

diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 4f1472409ef8..cb305e71e7de 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -28,6 +28,69 @@ void cgroup_bpf_offline(struct cgroup *cgrp)
 	percpu_ref_kill(&cgrp->bpf.refcnt);
 }
 
+static void bpf_cgroup_storages_free(struct bpf_cgroup_storage *storages[])
+{
+	enum bpf_cgroup_storage_type stype;
+
+	for_each_cgroup_storage_type(stype)
+		bpf_cgroup_storage_free(storages[stype]);
+}
+
+static int bpf_cgroup_storages_alloc(struct bpf_cgroup_storage *storages[],
+				     struct bpf_prog *prog)
+{
+	enum bpf_cgroup_storage_type stype;
+
+	for_each_cgroup_storage_type(stype) {
+		storages[stype] = bpf_cgroup_storage_alloc(prog, stype);
+		if (IS_ERR(storages[stype])) {
+			storages[stype] = NULL;
+			bpf_cgroup_storages_free(storages);
+			return -ENOMEM;
+		}
+	}
+
+	return 0;
+}
+
+static void bpf_cgroup_storages_assign(struct bpf_cgroup_storage *dst[],
+				       struct bpf_cgroup_storage *src[])
+{
+	enum bpf_cgroup_storage_type stype;
+
+	for_each_cgroup_storage_type(stype)
+		dst[stype] = src[stype];
+}
+
+static void bpf_cgroup_storages_link(struct bpf_cgroup_storage *storages[],
+				     struct cgroup* cgrp,
+				     enum bpf_attach_type attach_type)
+{
+	enum bpf_cgroup_storage_type stype;
+
+	for_each_cgroup_storage_type(stype)
+		bpf_cgroup_storage_link(storages[stype], cgrp, attach_type);
+}
+
+static void bpf_cgroup_storages_unlink(struct bpf_cgroup_storage *storages[])
+{
+	enum bpf_cgroup_storage_type stype;
+
+	for_each_cgroup_storage_type(stype)
+		bpf_cgroup_storage_unlink(storages[stype]);
+}
+
+/* Called when bpf_cgroup_link is auto-detached from dying cgroup.
+ * It drops cgroup and bpf_prog refcounts, and marks bpf_link as defunct. It
+ * doesn't free link memory, which will eventually be done by bpf_link's
+ * release() callback, when its last FD is closed.
+ */
+static void bpf_cgroup_link_auto_detach(struct bpf_cgroup_link *link)
+{
+	cgroup_put(link->cgroup);
+	link->cgroup = NULL;
+}
+
 /**
  * cgroup_bpf_release() - put references of all bpf programs and
  *                        release all cgroup bpf data
@@ -37,7 +100,6 @@ static void cgroup_bpf_release(struct work_struct *work)
 {
 	struct cgroup *p, *cgrp = container_of(work, struct cgroup,
 					       bpf.release_work);
-	enum bpf_cgroup_storage_type stype;
 	struct bpf_prog_array *old_array;
 	unsigned int type;
 
@@ -49,11 +111,12 @@ static void cgroup_bpf_release(struct work_struct *work)
 
 		list_for_each_entry_safe(pl, tmp, progs, node) {
 			list_del(&pl->node);
-			bpf_prog_put(pl->prog);
-			for_each_cgroup_storage_type(stype) {
-				bpf_cgroup_storage_unlink(pl->storage[stype]);
-				bpf_cgroup_storage_free(pl->storage[stype]);
-			}
+			if (pl->prog)
+				bpf_prog_put(pl->prog);
+			if (pl->link)
+				bpf_cgroup_link_auto_detach(pl->link);
+			bpf_cgroup_storages_unlink(pl->storage);
+			bpf_cgroup_storages_free(pl->storage);
 			kfree(pl);
 			static_branch_dec(&cgroup_bpf_enabled_key);
 		}
@@ -85,6 +148,18 @@ static void cgroup_bpf_release_fn(struct percpu_ref *ref)
 	queue_work(system_wq, &cgrp->bpf.release_work);
 }
 
+/* Get underlying bpf_prog of bpf_prog_list entry, regardless if it's through
+ * link or direct prog.
+ */
+static struct bpf_prog *prog_list_prog(struct bpf_prog_list *pl)
+{
+	if (pl->prog)
+		return pl->prog;
+	if (pl->link)
+		return pl->link->link.prog;
+	return NULL;
+}
+
 /* count number of elements in the list.
  * it's slow but the list cannot be long
  */
@@ -94,7 +169,7 @@ static u32 prog_list_length(struct list_head *head)
 	u32 cnt = 0;
 
 	list_for_each_entry(pl, head, node) {
-		if (!pl->prog)
+		if (!prog_list_prog(pl))
 			continue;
 		cnt++;
 	}
@@ -138,7 +213,7 @@ static int compute_effective_progs(struct cgroup *cgrp,
 				   enum bpf_attach_type type,
 				   struct bpf_prog_array **array)
 {
-	enum bpf_cgroup_storage_type stype;
+	struct bpf_prog_array_item *item;
 	struct bpf_prog_array *progs;
 	struct bpf_prog_list *pl;
 	struct cgroup *p = cgrp;
@@ -163,13 +238,13 @@ static int compute_effective_progs(struct cgroup *cgrp,
 			continue;
 
 		list_for_each_entry(pl, &p->bpf.progs[type], node) {
-			if (!pl->prog)
+			if (!prog_list_prog(pl))
 				continue;
 
-			progs->items[cnt].prog = pl->prog;
-			for_each_cgroup_storage_type(stype)
-				progs->items[cnt].cgroup_storage[stype] =
-					pl->storage[stype];
+			item = &progs->items[cnt];
+			item->prog = prog_list_prog(pl);
+			bpf_cgroup_storages_assign(item->cgroup_storage,
+						   pl->storage);
 			cnt++;
 		}
 	} while ((p = cgroup_parent(p)));
@@ -287,19 +362,60 @@ cleanup:
 
 #define BPF_CGROUP_MAX_PROGS 64
 
+static struct bpf_prog_list *find_attach_entry(struct list_head *progs,
+					       struct bpf_prog *prog,
+					       struct bpf_cgroup_link *link,
+					       struct bpf_prog *replace_prog,
+					       bool allow_multi)
+{
+	struct bpf_prog_list *pl;
+
+	/* single-attach case */
+	if (!allow_multi) {
+		if (list_empty(progs))
+			return NULL;
+		return list_first_entry(progs, typeof(*pl), node);
+	}
+
+	list_for_each_entry(pl, progs, node) {
+		if (prog && pl->prog == prog)
+			/* disallow attaching the same prog twice */
+			return ERR_PTR(-EINVAL);
+		if (link && pl->link == link)
+			/* disallow attaching the same link twice */
+			return ERR_PTR(-EINVAL);
+	}
+
+	/* direct prog multi-attach w/ replacement case */
+	if (replace_prog) {
+		list_for_each_entry(pl, progs, node) {
+			if (pl->prog == replace_prog)
+				/* a match found */
+				return pl;
+		}
+		/* prog to replace not found for cgroup */
+		return ERR_PTR(-ENOENT);
+	}
+
+	return NULL;
+}
+
 /**
- * __cgroup_bpf_attach() - Attach the program to a cgroup, and
+ * __cgroup_bpf_attach() - Attach the program or the link to a cgroup, and
  *                         propagate the change to descendants
  * @cgrp: The cgroup which descendants to traverse
  * @prog: A program to attach
+ * @link: A link to attach
  * @replace_prog: Previously attached program to replace if BPF_F_REPLACE is set
  * @type: Type of attach operation
  * @flags: Option flags
  *
+ * Exactly one of @prog or @link can be non-null.
  * Must be called with cgroup_mutex held.
  */
-int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
-			struct bpf_prog *replace_prog,
+int __cgroup_bpf_attach(struct cgroup *cgrp,
+			struct bpf_prog *prog, struct bpf_prog *replace_prog,
+			struct bpf_cgroup_link *link,
 			enum bpf_attach_type type, u32 flags)
 {
 	u32 saved_flags = (flags & (BPF_F_ALLOW_OVERRIDE | BPF_F_ALLOW_MULTI));
@@ -307,14 +423,19 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
 	struct bpf_prog *old_prog = NULL;
 	struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {};
 	struct bpf_cgroup_storage *old_storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {};
-	struct bpf_prog_list *pl, *replace_pl = NULL;
-	enum bpf_cgroup_storage_type stype;
+	struct bpf_prog_list *pl;
 	int err;
 
 	if (((flags & BPF_F_ALLOW_OVERRIDE) && (flags & BPF_F_ALLOW_MULTI)) ||
 	    ((flags & BPF_F_REPLACE) && !(flags & BPF_F_ALLOW_MULTI)))
 		/* invalid combination */
 		return -EINVAL;
+	if (link && (prog || replace_prog))
+		/* only either link or prog/replace_prog can be specified */
+		return -EINVAL;
+	if (!!replace_prog != !!(flags & BPF_F_REPLACE))
+		/* replace_prog implies BPF_F_REPLACE, and vice versa */
+		return -EINVAL;
 
 	if (!hierarchy_allows_attach(cgrp, type))
 		return -EPERM;
@@ -329,140 +450,203 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
 	if (prog_list_length(progs) >= BPF_CGROUP_MAX_PROGS)
 		return -E2BIG;
 
-	if (flags & BPF_F_ALLOW_MULTI) {
-		list_for_each_entry(pl, progs, node) {
-			if (pl->prog == prog)
-				/* disallow attaching the same prog twice */
-				return -EINVAL;
-			if (pl->prog == replace_prog)
-				replace_pl = pl;
-		}
-		if ((flags & BPF_F_REPLACE) && !replace_pl)
-			/* prog to replace not found for cgroup */
-			return -ENOENT;
-	} else if (!list_empty(progs)) {
-		replace_pl = list_first_entry(progs, typeof(*pl), node);
-	}
+	pl = find_attach_entry(progs, prog, link, replace_prog,
+			       flags & BPF_F_ALLOW_MULTI);
+	if (IS_ERR(pl))
+		return PTR_ERR(pl);
 
-	for_each_cgroup_storage_type(stype) {
-		storage[stype] = bpf_cgroup_storage_alloc(prog, stype);
-		if (IS_ERR(storage[stype])) {
-			storage[stype] = NULL;
-			for_each_cgroup_storage_type(stype)
-				bpf_cgroup_storage_free(storage[stype]);
-			return -ENOMEM;
-		}
-	}
+	if (bpf_cgroup_storages_alloc(storage, prog ? : link->link.prog))
+		return -ENOMEM;
 
-	if (replace_pl) {
-		pl = replace_pl;
+	if (pl) {
 		old_prog = pl->prog;
-		for_each_cgroup_storage_type(stype) {
-			old_storage[stype] = pl->storage[stype];
-			bpf_cgroup_storage_unlink(old_storage[stype]);
-		}
+		bpf_cgroup_storages_unlink(pl->storage);
+		bpf_cgroup_storages_assign(old_storage, pl->storage);
 	} else {
 		pl = kmalloc(sizeof(*pl), GFP_KERNEL);
 		if (!pl) {
-			for_each_cgroup_storage_type(stype)
-				bpf_cgroup_storage_free(storage[stype]);
+			bpf_cgroup_storages_free(storage);
 			return -ENOMEM;
 		}
 		list_add_tail(&pl->node, progs);
 	}
 
 	pl->prog = prog;
-	for_each_cgroup_storage_type(stype)
-		pl->storage[stype] = storage[stype];
-
+	pl->link = link;
+	bpf_cgroup_storages_assign(pl->storage, storage);
 	cgrp->bpf.flags[type] = saved_flags;
 
 	err = update_effective_progs(cgrp, type);
 	if (err)
 		goto cleanup;
 
-	static_branch_inc(&cgroup_bpf_enabled_key);
-	for_each_cgroup_storage_type(stype) {
-		if (!old_storage[stype])
-			continue;
-		bpf_cgroup_storage_free(old_storage[stype]);
-	}
-	if (old_prog) {
+	bpf_cgroup_storages_free(old_storage);
+	if (old_prog)
 		bpf_prog_put(old_prog);
-		static_branch_dec(&cgroup_bpf_enabled_key);
-	}
-	for_each_cgroup_storage_type(stype)
-		bpf_cgroup_storage_link(storage[stype], cgrp, type);
+	else
+		static_branch_inc(&cgroup_bpf_enabled_key);
+	bpf_cgroup_storages_link(pl->storage, cgrp, type);
 	return 0;
 
 cleanup:
-	/* and cleanup the prog list */
-	pl->prog = old_prog;
-	for_each_cgroup_storage_type(stype) {
-		bpf_cgroup_storage_free(pl->storage[stype]);
-		pl->storage[stype] = old_storage[stype];
-		bpf_cgroup_storage_link(old_storage[stype], cgrp, type);
+	if (old_prog) {
+		pl->prog = old_prog;
+		pl->link = NULL;
 	}
-	if (!replace_pl) {
+	bpf_cgroup_storages_free(pl->storage);
+	bpf_cgroup_storages_assign(pl->storage, old_storage);
+	bpf_cgroup_storages_link(pl->storage, cgrp, type);
+	if (!old_prog) {
 		list_del(&pl->node);
 		kfree(pl);
 	}
 	return err;
 }
 
+/* Swap updated BPF program for given link in effective program arrays across
+ * all descendant cgroups. This function is guaranteed to succeed.
+ */
+static void replace_effective_prog(struct cgroup *cgrp,
+				   enum bpf_attach_type type,
+				   struct bpf_cgroup_link *link)
+{
+	struct bpf_prog_array_item *item;
+	struct cgroup_subsys_state *css;
+	struct bpf_prog_array *progs;
+	struct bpf_prog_list *pl;
+	struct list_head *head;
+	struct cgroup *cg;
+	int pos;
+
+	css_for_each_descendant_pre(css, &cgrp->self) {
+		struct cgroup *desc = container_of(css, struct cgroup, self);
+
+		if (percpu_ref_is_zero(&desc->bpf.refcnt))
+			continue;
+
+		/* find position of link in effective progs array */
+		for (pos = 0, cg = desc; cg; cg = cgroup_parent(cg)) {
+			if (pos && !(cg->bpf.flags[type] & BPF_F_ALLOW_MULTI))
+				continue;
+
+			head = &cg->bpf.progs[type];
+			list_for_each_entry(pl, head, node) {
+				if (!prog_list_prog(pl))
+					continue;
+				if (pl->link == link)
+					goto found;
+				pos++;
+			}
+		}
+found:
+		BUG_ON(!cg);
+		progs = rcu_dereference_protected(
+				desc->bpf.effective[type],
+				lockdep_is_held(&cgroup_mutex));
+		item = &progs->items[pos];
+		WRITE_ONCE(item->prog, link->link.prog);
+	}
+}
+
 /**
- * __cgroup_bpf_detach() - Detach the program from a cgroup, and
+ * __cgroup_bpf_replace() - Replace link's program and propagate the change
+ *                          to descendants
+ * @cgrp: The cgroup which descendants to traverse
+ * @link: A link for which to replace BPF program
+ * @type: Type of attach operation
+ *
+ * Must be called with cgroup_mutex held.
+ */
+int __cgroup_bpf_replace(struct cgroup *cgrp, struct bpf_cgroup_link *link,
+			 struct bpf_prog *new_prog)
+{
+	struct list_head *progs = &cgrp->bpf.progs[link->type];
+	struct bpf_prog *old_prog;
+	struct bpf_prog_list *pl;
+	bool found = false;
+
+	if (link->link.prog->type != new_prog->type)
+		return -EINVAL;
+
+	list_for_each_entry(pl, progs, node) {
+		if (pl->link == link) {
+			found = true;
+			break;
+		}
+	}
+	if (!found)
+		return -ENOENT;
+
+	old_prog = xchg(&link->link.prog, new_prog);
+	replace_effective_prog(cgrp, link->type, link);
+	bpf_prog_put(old_prog);
+	return 0;
+}
+
+static struct bpf_prog_list *find_detach_entry(struct list_head *progs,
+					       struct bpf_prog *prog,
+					       struct bpf_cgroup_link *link,
+					       bool allow_multi)
+{
+	struct bpf_prog_list *pl;
+
+	if (!allow_multi) {
+		if (list_empty(progs))
+			/* report error when trying to detach and nothing is attached */
+			return ERR_PTR(-ENOENT);
+
+		/* to maintain backward compatibility NONE and OVERRIDE cgroups
+		 * allow detaching with invalid FD (prog==NULL) in legacy mode
+		 */
+		return list_first_entry(progs, typeof(*pl), node);
+	}
+
+	if (!prog && !link)
+		/* to detach MULTI prog the user has to specify valid FD
+		 * of the program or link to be detached
+		 */
+		return ERR_PTR(-EINVAL);
+
+	/* find the prog or link and detach it */
+	list_for_each_entry(pl, progs, node) {
+		if (pl->prog == prog && pl->link == link)
+			return pl;
+	}
+	return ERR_PTR(-ENOENT);
+}
+
+/**
+ * __cgroup_bpf_detach() - Detach the program or link from a cgroup, and
  *                         propagate the change to descendants
  * @cgrp: The cgroup which descendants to traverse
  * @prog: A program to detach or NULL
+ * @prog: A link to detach or NULL
  * @type: Type of detach operation
  *
+ * At most one of @prog or @link can be non-NULL.
  * Must be called with cgroup_mutex held.
  */
 int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
-			enum bpf_attach_type type)
+			struct bpf_cgroup_link *link, enum bpf_attach_type type)
 {
 	struct list_head *progs = &cgrp->bpf.progs[type];
-	enum bpf_cgroup_storage_type stype;
 	u32 flags = cgrp->bpf.flags[type];
-	struct bpf_prog *old_prog = NULL;
 	struct bpf_prog_list *pl;
+	struct bpf_prog *old_prog;
 	int err;
 
-	if (flags & BPF_F_ALLOW_MULTI) {
-		if (!prog)
-			/* to detach MULTI prog the user has to specify valid FD
-			 * of the program to be detached
-			 */
-			return -EINVAL;
-	} else {
-		if (list_empty(progs))
-			/* report error when trying to detach and nothing is attached */
-			return -ENOENT;
-	}
+	if (prog && link)
+		/* only one of prog or link can be specified */
+		return -EINVAL;
 
-	if (flags & BPF_F_ALLOW_MULTI) {
-		/* find the prog and detach it */
-		list_for_each_entry(pl, progs, node) {
-			if (pl->prog != prog)
-				continue;
-			old_prog = prog;
-			/* mark it deleted, so it's ignored while
-			 * recomputing effective
-			 */
-			pl->prog = NULL;
-			break;
-		}
-		if (!old_prog)
-			return -ENOENT;
-	} else {
-		/* to maintain backward compatibility NONE and OVERRIDE cgroups
-		 * allow detaching with invalid FD (prog==NULL)
-		 */
-		pl = list_first_entry(progs, typeof(*pl), node);
-		old_prog = pl->prog;
-		pl->prog = NULL;
-	}
+	pl = find_detach_entry(progs, prog, link, flags & BPF_F_ALLOW_MULTI);
+	if (IS_ERR(pl))
+		return PTR_ERR(pl);
+
+	/* mark it deleted, so it's ignored while recomputing effective */
+	old_prog = pl->prog;
+	pl->prog = NULL;
+	pl->link = NULL;
 
 	err = update_effective_progs(cgrp, type);
 	if (err)
@@ -470,22 +654,21 @@ int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
 
 	/* now can actually delete it from this cgroup list */
 	list_del(&pl->node);
-	for_each_cgroup_storage_type(stype) {
-		bpf_cgroup_storage_unlink(pl->storage[stype]);
-		bpf_cgroup_storage_free(pl->storage[stype]);
-	}
+	bpf_cgroup_storages_unlink(pl->storage);
+	bpf_cgroup_storages_free(pl->storage);
 	kfree(pl);
 	if (list_empty(progs))
 		/* last program was detached, reset flags to zero */
 		cgrp->bpf.flags[type] = 0;
-
-	bpf_prog_put(old_prog);
+	if (old_prog)
+		bpf_prog_put(old_prog);
 	static_branch_dec(&cgroup_bpf_enabled_key);
 	return 0;
 
 cleanup:
-	/* and restore back old_prog */
+	/* restore back prog or link */
 	pl->prog = old_prog;
+	pl->link = link;
 	return err;
 }
 
@@ -498,6 +681,7 @@ int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
 	struct list_head *progs = &cgrp->bpf.progs[type];
 	u32 flags = cgrp->bpf.flags[type];
 	struct bpf_prog_array *effective;
+	struct bpf_prog *prog;
 	int cnt, ret = 0, i;
 
 	effective = rcu_dereference_protected(cgrp->bpf.effective[type],
@@ -528,7 +712,8 @@ int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
 
 		i = 0;
 		list_for_each_entry(pl, progs, node) {
-			id = pl->prog->aux->id;
+			prog = prog_list_prog(pl);
+			id = prog->aux->id;
 			if (copy_to_user(prog_ids + i, &id, sizeof(id)))
 				return -EFAULT;
 			if (++i == cnt)
@@ -558,8 +743,8 @@ int cgroup_bpf_prog_attach(const union bpf_attr *attr,
 		}
 	}
 
-	ret = cgroup_bpf_attach(cgrp, prog, replace_prog, attr->attach_type,
-				attr->attach_flags);
+	ret = cgroup_bpf_attach(cgrp, prog, replace_prog, NULL,
+				attr->attach_type, attr->attach_flags);
 
 	if (replace_prog)
 		bpf_prog_put(replace_prog);
@@ -581,7 +766,7 @@ int cgroup_bpf_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype)
 	if (IS_ERR(prog))
 		prog = NULL;
 
-	ret = cgroup_bpf_detach(cgrp, prog, attr->attach_type, 0);
+	ret = cgroup_bpf_detach(cgrp, prog, attr->attach_type);
 	if (prog)
 		bpf_prog_put(prog);
 
@@ -589,6 +774,90 @@ int cgroup_bpf_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype)
 	return ret;
 }
 
+static void bpf_cgroup_link_release(struct bpf_link *link)
+{
+	struct bpf_cgroup_link *cg_link =
+		container_of(link, struct bpf_cgroup_link, link);
+
+	/* link might have been auto-detached by dying cgroup already,
+	 * in that case our work is done here
+	 */
+	if (!cg_link->cgroup)
+		return;
+
+	mutex_lock(&cgroup_mutex);
+
+	/* re-check cgroup under lock again */
+	if (!cg_link->cgroup) {
+		mutex_unlock(&cgroup_mutex);
+		return;
+	}
+
+	WARN_ON(__cgroup_bpf_detach(cg_link->cgroup, NULL, cg_link,
+				    cg_link->type));
+
+	mutex_unlock(&cgroup_mutex);
+	cgroup_put(cg_link->cgroup);
+}
+
+static void bpf_cgroup_link_dealloc(struct bpf_link *link)
+{
+	struct bpf_cgroup_link *cg_link =
+		container_of(link, struct bpf_cgroup_link, link);
+
+	kfree(cg_link);
+}
+
+const struct bpf_link_ops bpf_cgroup_link_lops = {
+	.release = bpf_cgroup_link_release,
+	.dealloc = bpf_cgroup_link_dealloc,
+};
+
+int cgroup_bpf_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
+{
+	struct bpf_cgroup_link *link;
+	struct file *link_file;
+	struct cgroup *cgrp;
+	int err, link_fd;
+
+	if (attr->link_create.flags)
+		return -EINVAL;
+
+	cgrp = cgroup_get_from_fd(attr->link_create.target_fd);
+	if (IS_ERR(cgrp))
+		return PTR_ERR(cgrp);
+
+	link = kzalloc(sizeof(*link), GFP_USER);
+	if (!link) {
+		err = -ENOMEM;
+		goto out_put_cgroup;
+	}
+	bpf_link_init(&link->link, &bpf_cgroup_link_lops, prog);
+	link->cgroup = cgrp;
+	link->type = attr->link_create.attach_type;
+
+	link_file = bpf_link_new_file(&link->link, &link_fd);
+	if (IS_ERR(link_file)) {
+		kfree(link);
+		err = PTR_ERR(link_file);
+		goto out_put_cgroup;
+	}
+
+	err = cgroup_bpf_attach(cgrp, NULL, NULL, link, link->type,
+				BPF_F_ALLOW_MULTI);
+	if (err) {
+		bpf_link_cleanup(&link->link, link_file, link_fd);
+		goto out_put_cgroup;
+	}
+
+	fd_install(link_fd, link_file);
+	return link_fd;
+
+out_put_cgroup:
+	cgroup_put(cgrp);
+	return err;
+}
+
 int cgroup_bpf_prog_query(const union bpf_attr *attr,
 			  union bpf_attr __user *uattr)
 {