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

Breno Leitao
2023-09-04T16:25:39Z

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