Hello Gabriel,
On Wed, Aug 09, 2023 at 12:46:27PM -0400, Gabriel Krisman Bertazi wrote:
> Breno Leitao <leitao@xxxxxxxxxx> writes:
>
> > Add BPF hooks support for getsockopts io_uring command. So, bpf cgroups
> > programs can run when SOCKET_URING_OP_GETSOCKOPT command is called.
> >
> > This implementation follows a similar approach to what
> > __sys_getsockopt() does, but, using USER_SOCKPTR() for optval instead of
> > kernel pointer.
> >
> > Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx>
> > ---
> > io_uring/uring_cmd.c | 18 +++++++++++++-----
> > 1 file changed, 13 insertions(+), 5 deletions(-)
> >
> > diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
> > index dbba005a7290..3693e5779229 100644
> > --- a/io_uring/uring_cmd.c
> > +++ b/io_uring/uring_cmd.c
> > @@ -5,6 +5,8 @@
> > #include <linux/io_uring.h>
> > #include <linux/security.h>
> > #include <linux/nospec.h>
> > +#include <linux/compat.h>
> > +#include <linux/bpf-cgroup.h>
> >
> > #include <uapi/linux/io_uring.h>
> > #include <uapi/asm-generic/ioctls.h>
> > @@ -179,17 +181,23 @@ static inline int io_uring_cmd_getsockopt(struct socket *sock,
> > if (err)
> > return err;
> >
> > - if (level == SOL_SOCKET) {
> > + err = -EOPNOTSUPP;
> > + if (level == SOL_SOCKET)
> > err = sk_getsockopt(sock->sk, level, optname,
> > USER_SOCKPTR(optval),
> > KERNEL_SOCKPTR(&optlen));
> > - if (err)
> > - return err;
> >
> > + if (!in_compat_syscall())
> > + err = BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock->sk, level,
> > + optname,
> > + USER_SOCKPTR(optval),
> > + KERNEL_SOCKPTR(&optlen),
> > + optlen, err);
>
> I'm not sure if it makes sense to use in_compat_syscall() here. Can't
> this be invoked in a ring with ctx->compat set, but from outside a
> compat syscall context (i.e. from sqpoll or even a !compat
> io_uring_enter syscall)? I suspect you might need to check ctx->compact
> instead, but I'm not sure. Did you consider that?
I think that checking ctx->compat seems to be the right thing to do. I
will update.
