Commit f5836749 authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Daniel Borkmann
Browse files

bpf: Add BPF_CGROUP_INET_SOCK_RELEASE hook 



Sometimes it's handy to know when the socket gets freed. In
particular, we'd like to try to use a smarter allocation of
ports for bpf_bind and explore the possibility of limiting
the number of SOCK_DGRAM sockets the process can have.

Implement BPF_CGROUP_INET_SOCK_RELEASE hook that triggers on
inet socket release. It triggers only for userspace sockets
(not in-kernel ones) and therefore has the same semantics as
the existing BPF_CGROUP_INET_SOCK_CREATE.

Signed-off-by: default avatarStanislav Fomichev <sdf@google.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200706230128.4073544-2-sdf@google.com
parent 4e48978c

include/linux/bpf-cgroup.h

+4 −0
Original line number Diff line number Diff line
@@ -210,6 +210,9 @@ int bpf_percpu_cgroup_storage_update(struct bpf_map *map, void *key, 
#define BPF_CGROUP_RUN_PROG_INET_SOCK(sk)				       \

	BPF_CGROUP_RUN_SK_PROG(sk, BPF_CGROUP_INET_SOCK_CREATE)



#define BPF_CGROUP_RUN_PROG_INET_SOCK_RELEASE(sk)			       \

	BPF_CGROUP_RUN_SK_PROG(sk, BPF_CGROUP_INET_SOCK_RELEASE)



#define BPF_CGROUP_RUN_PROG_INET4_POST_BIND(sk)				       \

	BPF_CGROUP_RUN_SK_PROG(sk, BPF_CGROUP_INET4_POST_BIND)
@@ -401,6 +404,7 @@ static inline int bpf_percpu_cgroup_storage_update(struct bpf_map *map, 
#define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk,skb) ({ 0; })

#define BPF_CGROUP_RUN_PROG_INET_EGRESS(sk,skb) ({ 0; })

#define BPF_CGROUP_RUN_PROG_INET_SOCK(sk) ({ 0; })

#define BPF_CGROUP_RUN_PROG_INET_SOCK_RELEASE(sk) ({ 0; })

#define BPF_CGROUP_RUN_PROG_INET4_BIND(sk, uaddr) ({ 0; })

#define BPF_CGROUP_RUN_PROG_INET6_BIND(sk, uaddr) ({ 0; })

#define BPF_CGROUP_RUN_PROG_INET4_POST_BIND(sk) ({ 0; })

include/uapi/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -226,6 +226,7 @@ enum bpf_attach_type { 
	BPF_CGROUP_INET4_GETSOCKNAME,

	BPF_CGROUP_INET6_GETSOCKNAME,

	BPF_XDP_DEVMAP,

	BPF_CGROUP_INET_SOCK_RELEASE,

	__MAX_BPF_ATTACH_TYPE

};

kernel/bpf/syscall.c

+3 −0
Original line number Diff line number Diff line
@@ -1981,6 +1981,7 @@ bpf_prog_load_check_attach(enum bpf_prog_type prog_type, 
	case BPF_PROG_TYPE_CGROUP_SOCK:

		switch (expected_attach_type) {

		case BPF_CGROUP_INET_SOCK_CREATE:

		case BPF_CGROUP_INET_SOCK_RELEASE:

		case BPF_CGROUP_INET4_POST_BIND:

		case BPF_CGROUP_INET6_POST_BIND:

			return 0;
@@ -2779,6 +2780,7 @@ attach_type_to_prog_type(enum bpf_attach_type attach_type) 
		return BPF_PROG_TYPE_CGROUP_SKB;

		break;

	case BPF_CGROUP_INET_SOCK_CREATE:

	case BPF_CGROUP_INET_SOCK_RELEASE:

	case BPF_CGROUP_INET4_POST_BIND:

	case BPF_CGROUP_INET6_POST_BIND:

		return BPF_PROG_TYPE_CGROUP_SOCK;
@@ -2929,6 +2931,7 @@ static int bpf_prog_query(const union bpf_attr *attr, 
	case BPF_CGROUP_INET_INGRESS:

	case BPF_CGROUP_INET_EGRESS:

	case BPF_CGROUP_INET_SOCK_CREATE:

	case BPF_CGROUP_INET_SOCK_RELEASE:

	case BPF_CGROUP_INET4_BIND:

	case BPF_CGROUP_INET6_BIND:

	case BPF_CGROUP_INET4_POST_BIND:

net/core/filter.c

+1 −0
Original line number Diff line number Diff line
@@ -6890,6 +6890,7 @@ static bool __sock_filter_check_attach_type(int off, 
	case offsetof(struct bpf_sock, priority):

		switch (attach_type) {

		case BPF_CGROUP_INET_SOCK_CREATE:

		case BPF_CGROUP_INET_SOCK_RELEASE:

			goto full_access;

		default:

			return false;

net/ipv4/af_inet.c

+3 −0
Original line number Diff line number Diff line
@@ -411,6 +411,9 @@ int inet_release(struct socket *sock) 
	if (sk) {

		long timeout;



		if (!sk->sk_kern_sock)

			BPF_CGROUP_RUN_PROG_INET_SOCK_RELEASE(sk);



		/* Applications forget to leave groups before exiting */

		ip_mc_drop_socket(sk);

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