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Commit 8d20aabe authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

ebpf: add helper to retrieve net_cls's classid cookie 



It would be very useful to retrieve the net_cls's classid from an eBPF
program to allow for a more fine-grained classification, it could be
directly used or in conjunction with additional policies. I.e. docker,
but also tooling such as cgexec, can easily run applications via net_cls
cgroups:

  cgcreate -g net_cls:/foo
  echo 42 > foo/net_cls.classid
  cgexec -g net_cls:foo <prog>

Thus, their respecitve classid cookie of foo can then be looked up on
the egress path to apply further policies. The helper is desigend such
that a non-zero value returns the cgroup id.

Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Cc: Thomas Graf <tgraf@suug.ch>
Acked-by: default avatarAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b87a173e

include/uapi/linux/bpf.h

+7 −0
Original line number Diff line number Diff line
@@ -249,6 +249,13 @@ enum bpf_func_id { 
	 * Return: 0 on success

	 */

	BPF_FUNC_get_current_comm,



	/**

	 * bpf_get_cgroup_classid(skb) - retrieve a proc's classid

	 * @skb: pointer to skb

	 * Return: classid if != 0

	 */

	BPF_FUNC_get_cgroup_classid,

	__BPF_FUNC_MAX_ID,

};

net/core/filter.c

+15 −0
Original line number Diff line number Diff line
@@ -47,6 +47,7 @@ 
#include <linux/if_vlan.h>

#include <linux/bpf.h>

#include <net/sch_generic.h>

#include <net/cls_cgroup.h>



/**

 *	sk_filter - run a packet through a socket filter
@@ -1424,6 +1425,18 @@ const struct bpf_func_proto bpf_clone_redirect_proto = { 
	.arg3_type      = ARG_ANYTHING,

};



static u64 bpf_get_cgroup_classid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)

{

	return task_get_classid((struct sk_buff *) (unsigned long) r1);

}



static const struct bpf_func_proto bpf_get_cgroup_classid_proto = {

	.func           = bpf_get_cgroup_classid,

	.gpl_only       = false,

	.ret_type       = RET_INTEGER,

	.arg1_type      = ARG_PTR_TO_CTX,

};



static const struct bpf_func_proto *

sk_filter_func_proto(enum bpf_func_id func_id)

{
@@ -1461,6 +1474,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id) 
		return &bpf_l4_csum_replace_proto;

	case BPF_FUNC_clone_redirect:

		return &bpf_clone_redirect_proto;

	case BPF_FUNC_get_cgroup_classid:

		return &bpf_get_cgroup_classid_proto;

	default:

		return sk_filter_func_proto(func_id);

	}