From: Stanislav Fomichev <sdf@google.com>
Date: Mon, 6 Jul 2020 16:01:25 -0700
Subject: bpf: Add BPF_CGROUP_INET_SOCK_RELEASE hook
Patch-mainline: v5.9-rc1
Git-commit: f5836749c9c04a10decd2742845ad4870965fdef
References: bsc#1177028
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: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200706230128.4073544-2-sdf@google.com
Acked-by: Gary Lin <glin@suse.com>
---
include/linux/bpf-cgroup.h | 4 ++++
include/uapi/linux/bpf.h | 1 +
kernel/bpf/syscall.c | 3 +++
net/core/filter.c | 1 +
net/ipv4/af_inet.c | 3 +++
5 files changed, 12 insertions(+)
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -211,6 +211,9 @@ int bpf_percpu_cgroup_storage_update(str
#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)
@@ -402,6 +405,7 @@ static inline int bpf_percpu_cgroup_stor
#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; })
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -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
};
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1978,6 +1978,7 @@ bpf_prog_load_check_attach(enum bpf_prog
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;
@@ -2776,6 +2777,7 @@ attach_type_to_prog_type(enum bpf_attach
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;
@@ -2924,6 +2926,7 @@ static int bpf_prog_query(const union bp
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:
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -6858,6 +6858,7 @@ static bool __sock_filter_check_attach_t
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;
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -410,6 +410,9 @@ 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);