[PATCH v4 00/10] io_uring: Initial support for {s,g}etsockopt commands

[Breno Leitao <leitao@debian.org>]

This patchset adds support for getsockopt (SOCKET_URING_OP_GETSOCKOPT)
and setsockopt (SOCKET_URING_OP_SETSOCKOPT) in io_uring commands.
SOCKET_URING_OP_SETSOCKOPT implements generic case, covering all levels
and optnames. SOCKET_URING_OP_GETSOCKOPT is limited, for now, to
SOL_SOCKET level, which seems to be the most common level parameter for
get/setsockopt(2).

In order to keep the implementation (and tests) simple, some refactors
were done prior to the changes, as follows:

Patches 1-2: Modify the BPF hooks to support sockptr_t, so, these functions
become flexible enough to accept user or kernel pointers for optval/optlen.

Patch 3-4:  Remove the core {s,g}etsockopt() core function from
__sys_{g,s}etsockopt, so, the code could be reused by other callers,
such as io_uring.

Patch 5: Pass compat mode to the file/socket callbacks

Patch 6: Move io_uring helpers from io_uring_zerocopy_tx to a generic
io_uring headers. This simplify the test case (last patch)

Patch 7: Protect io_uring_cmd_sock() to not be called if CONFIG_NET is
disabled.

PS1: For getsockopt command, the optlen field is not a userspace
pointers, but an absolute value, so this is slightly different from
getsockopt(2) behaviour. The new optlen value is returned in cqe->res.

PS2: The userspace pointers need to be alive until the operation is
completed.

These changes were tested with a new test[1] in liburing, LTP sockopt*
tests, as also with bpf/progs/sockopt test case, which is now adapted to
run using both system calls and io_uring commands.

[1] Link: https://github.com/leitao/liburing/blob/getsockopt/test/socket-getsetsock-cmd.c

RFC -> V1:
	* Copy user memory at io_uring subsystem, and call proto_ops
	  callbacks using kernel memory
	* Implement all the cases for SOCKET_URING_OP_SETSOCKOPT

V1 -> V2
	* Implemented the BPF part
	* Using user pointers from optval to avoid kmalloc in io_uring part.

V2 -> V3:
	* Break down __sys_setsockopt and reuse the core code, avoiding
	  duplicated code. This removed the requirement to expose
	  sock_use_custom_sol_socket().
	* Added io_uring test to selftests/bpf/sockopt.
	* Fixed compat argument, by passing it to the issue_flags.

V3 -> V4:
	* Rebase on top of commit 1ded5e5a5931b ("net: annotate data-races around sock->ops")
	* Also broke down __sys_setsockopt() to reuse the core function
	  from io_uring.
	* Create a new patch to return -EOPNOTSUPP if CONFIG_NET is
	  disabled
	* Added two SOL_SOCKET tests in bpf/prog_tests/sockopt.c

Breno Leitao (10):
  bpf: Leverage sockptr_t in BPF getsockopt hook
  bpf: Leverage sockptr_t in BPF setsockopt hook
  net/socket: Break down __sys_setsockopt
  net/socket: Break down __sys_getsockopt
  io_uring/cmd: Pass compat mode in issue_flags
  selftests/net: Extract uring helpers to be reusable
  io_uring/cmd: return -EOPNOTSUPP if net is disabled
  io_uring/cmd: Introduce SOCKET_URING_OP_GETSOCKOPT
  io_uring/cmd: Introduce SOCKET_URING_OP_SETSOCKOPT
  selftests/bpf/sockopt: Add io_uring support

 include/linux/bpf-cgroup.h                    |   9 +-
 include/linux/io_uring.h                      |   1 +
 include/net/sock.h                            |   4 +
 include/uapi/linux/io_uring.h                 |   8 +
 io_uring/uring_cmd.c                          |  55 ++++
 kernel/bpf/cgroup.c                           |  25 +-
 net/core/sock.c                               |   8 -
 net/socket.c                                  | 102 ++++---
 tools/include/io_uring/mini_liburing.h        | 282 ++++++++++++++++++
 .../selftests/bpf/prog_tests/sockopt.c        | 113 ++++++-
 tools/testing/selftests/net/Makefile          |   1 +
 .../selftests/net/io_uring_zerocopy_tx.c      | 268 +----------------
 12 files changed, 544 insertions(+), 332 deletions(-)
 create mode 100644 tools/include/io_uring/mini_liburing.h

-- 
2.34.1