Merge branch 'cgroup-bpf'

Daniel Mack says:

====================
Add eBPF hooks for cgroups

This is v9 of the patch set to allow eBPF programs for network
filtering and accounting to be attached to cgroups, so that they apply
to all sockets of all tasks placed in that cgroup. The logic also
allows to be extendeded for other cgroup based eBPF logic.

Again, only minor details are updated in this version.

Changes from v8:

* Move the egress hooks into ip_finish_output() and ip6_finish_output()
  so they run after the netfilter hooks. For IPv4 multicast, add a new
  ip_mc_finish_output() callback that is invoked on success by
  netfilter, and call the eBPF program from there.

Changes from v7:

* Replace the static inline function cgroup_bpf_run_filter() with
  two specific macros for ingress and egress.  This addresses David
  Miller's concern regarding skb->sk vs. sk in the egress path.
  Thanks a lot to Daniel Borkmann and Alexei Starovoitov for the
  suggestions.

Changes from v6:

* Rebased to 4.9-rc2

* Add EXPORT_SYMBOL(__cgroup_bpf_run_filter). The kbuild test robot
  now succeeds in building this version of the patch set.

* Switch from bpf_prog_run_save_cb() to bpf_prog_run_clear_cb() to not
  tamper with the contents of skb->cb[]. Pointed out by Daniel
  Borkmann.

* Use sk_to_full_sk() in the egress path, as suggested by Daniel
  Borkmann.

* Renamed BPF_PROG_TYPE_CGROUP_SOCKET to BPF_PROG_TYPE_CGROUP_SKB, as
  requested by David Ahern.

* Added Alexei's Acked-by tags.

Changes from v5:

* The eBPF programs now operate on L3 rather than on L2 of the packets,
  and the egress hooks were moved from __dev_queue_xmit() to
  ip*_output().

* For BPF_PROG_TYPE_CGROUP_SOCKET, disallow direct access to the skb
  through BPF_LD_[ABS|IND] instructions, but hook up the
  bpf_skb_load_bytes() access helper instead. Thanks to Daniel Borkmann
  for the help.

Changes from v4:

* Plug an skb leak when dropping packets due to eBPF verdicts in
  __dev_queue_xmit(). Spotted by Daniel Borkmann.

* Check for sk_fullsock(sk) in __cgroup_bpf_run_filter() so we don't
  operate on timewait or request sockets. Suggested by Daniel Borkmann.

* Add missing @parent parameter in kerneldoc of __cgroup_bpf_update().
  Spotted by Rami Rosen.

* Include linux/jump_label.h from bpf-cgroup.h to fix a kbuild error.

Changes from v3:

* Dropped the _FILTER suffix from BPF_PROG_TYPE_CGROUP_SOCKET_FILTER,
  renamed BPF_ATTACH_TYPE_CGROUP_INET_{E,IN}GRESS to
  BPF_CGROUP_INET_{IN,E}GRESS and alias BPF_MAX_ATTACH_TYPE to
  __BPF_MAX_ATTACH_TYPE, as suggested by Daniel Borkmann.

* Dropped the attach_flags member from the anonymous struct for BPF
  attach operations in union bpf_attr. They can be added later on via
  CHECK_ATTR. Requested by Daniel Borkmann and Alexei.

* Release old_prog at the end of __cgroup_bpf_update rather that at
  the beginning to fix a race gap between program updates and their
  users. Spotted by Daniel Borkmann.

* Plugged an skb leak when dropping packets on the egress path.
  Spotted by Daniel Borkmann.

* Add cgroups@vger.kernel.org to the loop, as suggested by Rami Rosen.

* Some minor coding style adoptions not worth mentioning in particular.

Changes from v2:

* Fixed the RCU locking details Tejun pointed out.

* Assert bpf_attr.flags == 0 in BPF_PROG_DETACH syscall handler.

Changes from v1:

* Moved all bpf specific cgroup code into its own file, and stub
  out related functions for !CONFIG_CGROUP_BPF as static inline nops.
  This way, the call sites are not cluttered with #ifdef guards while
  the feature remains compile-time configurable.

* Implemented the new scheme proposed by Tejun. Per cgroup, store one
  set of pointers that are pinned to the cgroup, and one for the
  programs that are effective. When a program is attached or detached,
  the change is propagated to all the cgroup's descendants. If a
  subcgroup has its own pinned program, skip the whole subbranch in
  order to allow delegation models.

* The hookup for egress packets is now done from __dev_queue_xmit().

* A static key is now used in both the ingress and egress fast paths
  to keep performance penalties close to zero if the feature is
  not in use.

* Overall cleanup to make the accessors use the program arrays.
  This should make it much easier to add new program types, which
  will then automatically follow the pinned vs. effective logic.

* Fixed locking issues, as pointed out by Eric Dumazet and Alexei
  Starovoitov. Changes to the program array are now done with
  xchg() and are protected by cgroup_mutex.

* eBPF programs are now expected to return 1 to let the packet pass,
  not >= 0. Pointed out by Alexei.

* Operation is now limited to INET sockets, so local AF_UNIX sockets
  are not affected. The enum members are renamed accordingly. In case
  other socket families should be supported, this can be extended in
  the future.

* The sample program learned to support both ingress and egress, and
  can now optionally make the eBPF program drop packets by making it
  return 0.
====================

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

3 files changed, 60 insertions, 2 deletions

diff --git a/net/core/filter.c b/net/core/filter.c
index dece94fef005..ea315af56511 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -78,6 +78,10 @@ int sk_filter_trim_cap(struct sock *sk, struct sk_buff *skb, unsigned int cap)
 	if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC))
 		return -ENOMEM;
 
+	err = BPF_CGROUP_RUN_PROG_INET_INGRESS(sk, skb);
+	if (err)
+		return err;
+
 	err = security_sock_rcv_skb(sk, skb);
 	if (err)
 		return err;
@@ -2630,6 +2634,17 @@ xdp_func_proto(enum bpf_func_id func_id)
 	}
 }
 
+static const struct bpf_func_proto *
+cg_skb_func_proto(enum bpf_func_id func_id)
+{
+	switch (func_id) {
+	case BPF_FUNC_skb_load_bytes:
+		return &bpf_skb_load_bytes_proto;
+	default:
+		return sk_filter_func_proto(func_id);
+	}
+}
+
 static bool __is_valid_access(int off, int size, enum bpf_access_type type)
 {
 	if (off < 0 || off >= sizeof(struct __sk_buff))
@@ -2992,6 +3007,12 @@ static const struct bpf_verifier_ops xdp_ops = {
 	.convert_ctx_access	= xdp_convert_ctx_access,
 };
 
+static const struct bpf_verifier_ops cg_skb_ops = {
+	.get_func_proto		= cg_skb_func_proto,
+	.is_valid_access	= sk_filter_is_valid_access,
+	.convert_ctx_access	= sk_filter_convert_ctx_access,
+};
+
 static struct bpf_prog_type_list sk_filter_type __read_mostly = {
 	.ops	= &sk_filter_ops,
 	.type	= BPF_PROG_TYPE_SOCKET_FILTER,
@@ -3012,12 +3033,18 @@ static struct bpf_prog_type_list xdp_type __read_mostly = {
 	.type	= BPF_PROG_TYPE_XDP,
 };
 
+static struct bpf_prog_type_list cg_skb_type __read_mostly = {
+	.ops	= &cg_skb_ops,
+	.type	= BPF_PROG_TYPE_CGROUP_SKB,
+};
+
 static int __init register_sk_filter_ops(void)
 {
 	bpf_register_prog_type(&sk_filter_type);
 	bpf_register_prog_type(&sched_cls_type);
 	bpf_register_prog_type(&sched_act_type);
 	bpf_register_prog_type(&xdp_type);
+	bpf_register_prog_type(&cg_skb_type);
 
 	return 0;
 }
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 358f2c82b030..9af2b7853be4 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -74,6 +74,7 @@
 #include <net/checksum.h>
 #include <net/inetpeer.h>
 #include <net/lwtunnel.h>
+#include <linux/bpf-cgroup.h>
 #include <linux/igmp.h>
 #include <linux/netfilter_ipv4.h>
 #include <linux/netfilter_bridge.h>
@@ -285,6 +286,13 @@ static int ip_finish_output_gso(struct net *net, struct sock *sk,
 static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
 	unsigned int mtu;
+	int ret;
+
+	ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
+	if (ret) {
+		kfree_skb(skb);
+		return ret;
+	}
 
 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
 	/* Policy lookup after SNAT yielded a new policy */
@@ -303,6 +311,20 @@ static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *sk
 	return ip_finish_output2(net, sk, skb);
 }
 
+static int ip_mc_finish_output(struct net *net, struct sock *sk,
+			       struct sk_buff *skb)
+{
+	int ret;
+
+	ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
+	if (ret) {
+		kfree_skb(skb);
+		return ret;
+	}
+
+	return dev_loopback_xmit(net, sk, skb);
+}
+
 int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
 	struct rtable *rt = skb_rtable(skb);
@@ -340,7 +362,7 @@ int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 			if (newskb)
 				NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
 					net, sk, newskb, NULL, newskb->dev,
-					dev_loopback_xmit);
+					ip_mc_finish_output);
 		}
 
 		/* Multicasts with ttl 0 must not go beyond the host */
@@ -356,7 +378,7 @@ int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 		if (newskb)
 			NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
 				net, sk, newskb, NULL, newskb->dev,
-				dev_loopback_xmit);
+				ip_mc_finish_output);
 	}
 
 	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 312cbd0e5038..70d0de404197 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -39,6 +39,7 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 
+#include <linux/bpf-cgroup.h>
 #include <linux/netfilter.h>
 #include <linux/netfilter_ipv6.h>
 
@@ -131,6 +132,14 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *
 
 static int ip6_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
+	int ret;
+
+	ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
+	if (ret) {
+		kfree_skb(skb);
+		return ret;
+	}
+
 	if ((skb->len > ip6_skb_dst_mtu(skb) && !skb_is_gso(skb)) ||
 	    dst_allfrag(skb_dst(skb)) ||
 	    (IP6CB(skb)->frag_max_size && skb->len > IP6CB(skb)->frag_max_size))