bpf: Bpf_{g,s}etsockopt for struct bpf_sock_addr

Currently, bpf_getsockopt and bpf_setsockopt helpers operate on the
'struct bpf_sock_ops' context in BPF_PROG_TYPE_SOCK_OPS program.
Let's generalize them and make them available for 'struct bpf_sock_addr'.
That way, in the future, we can allow those helpers in more places.

As an example, let's expose those 'struct bpf_sock_addr' based helpers to
BPF_CGROUP_INET{4,6}_CONNECT hooks. That way we can override CC before the
connection is made.

v3:
* Expose custom helpers for bpf_sock_addr context instead of doing
  generic bpf_sock argument (as suggested by Daniel). Even with
  try_socket_lock that doesn't sleep we have a problem where context sk
  is already locked and socket lock is non-nestable.

v2:
* s/BPF_PROG_TYPE_CGROUP_SOCKOPT/BPF_PROG_TYPE_SOCK_OPS/

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200430233152.199403-1-sdf@google.com
This commit is contained in:
Stanislav Fomichev 2020-04-30 16:31:52 -07:00 committed by Andrii Nakryiko
parent 5c1c96c579
commit dfa07417ff

View File

@ -1587,7 +1587,7 @@ union bpf_attr {
* Return
* 0
*
* int bpf_setsockopt(struct bpf_sock_ops *bpf_socket, int level, int optname, void *optval, int optlen)
* int bpf_setsockopt(void *bpf_socket, int level, int optname, void *optval, int optlen)
* Description
* Emulate a call to **setsockopt()** on the socket associated to
* *bpf_socket*, which must be a full socket. The *level* at
@ -1595,6 +1595,11 @@ union bpf_attr {
* must be specified, see **setsockopt(2)** for more information.
* The option value of length *optlen* is pointed by *optval*.
*
* *bpf_socket* should be one of the following:
* * **struct bpf_sock_ops** for **BPF_PROG_TYPE_SOCK_OPS**.
* * **struct bpf_sock_addr** for **BPF_CGROUP_INET4_CONNECT**
* and **BPF_CGROUP_INET6_CONNECT**.
*
* This helper actually implements a subset of **setsockopt()**.
* It supports the following *level*\ s:
*
@ -1789,7 +1794,7 @@ union bpf_attr {
* Return
* 0 on success, or a negative error in case of failure.
*
* int bpf_getsockopt(struct bpf_sock_ops *bpf_socket, int level, int optname, void *optval, int optlen)
* int bpf_getsockopt(void *bpf_socket, int level, int optname, void *optval, int optlen)
* Description
* Emulate a call to **getsockopt()** on the socket associated to
* *bpf_socket*, which must be a full socket. The *level* at
@ -1798,6 +1803,11 @@ union bpf_attr {
* The retrieved value is stored in the structure pointed by
* *opval* and of length *optlen*.
*
* *bpf_socket* should be one of the following:
* * **struct bpf_sock_ops** for **BPF_PROG_TYPE_SOCK_OPS**.
* * **struct bpf_sock_addr** for **BPF_CGROUP_INET4_CONNECT**
* and **BPF_CGROUP_INET6_CONNECT**.
*
* This helper actually implements a subset of **getsockopt()**.
* It supports the following *level*\ s:
*