Re: [PATCH v5 2/8] net/socket: Break down __sys_getsockopt

[Paolo Abeni <pabeni@redhat.com>]

On Mon, 2023-09-11 at 03:34 -0700, Breno Leitao wrote:
> Split __sys_getsockopt() into two functions by removing the core
> logic into a sub-function (do_sock_getsockopt()). This will avoid
> code duplication when executing the same operation in other callers, for
> instance.
> 
> do_sock_getsockopt() will be called by io_uring getsockopt() command
> operation in the following patch.
> 
> Suggested-by: Martin KaFai Lau <martin.lau@linux.dev>
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
>  include/net/sock.h |  3 +++
>  net/socket.c       | 51 ++++++++++++++++++++++++++++------------------
>  2 files changed, 34 insertions(+), 20 deletions(-)
> 
> diff --git a/include/net/sock.h b/include/net/sock.h
> index aa8fb54ad0af..fbd568a43d28 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -1863,6 +1863,9 @@ int sock_setsockopt(struct socket *sock, int level, int op,
>  		    sockptr_t optval, unsigned int optlen);
>  int do_sock_setsockopt(struct socket *sock, bool compat, int level,
>  		       int optname, char __user *user_optval, int optlen);
> +int do_sock_getsockopt(struct socket *sock, bool compat, int level,
> +		       int optname, char __user *user_optval,
> +		       int __user *user_optlen);
>  
>  int sk_getsockopt(struct sock *sk, int level, int optname,
>  		  sockptr_t optval, sockptr_t optlen);
> diff --git a/net/socket.c b/net/socket.c
> index 360332e098d4..3ec779a56f79 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -2333,28 +2333,17 @@ SYSCALL_DEFINE5(setsockopt, int, fd, int, level, int, optname,
>  INDIRECT_CALLABLE_DECLARE(bool tcp_bpf_bypass_getsockopt(int level,
>  							 int optname));
>  
> -/*
> - *	Get a socket option. Because we don't know the option lengths we have
> - *	to pass a user mode parameter for the protocols to sort out.
> - */
> -int __sys_getsockopt(int fd, int level, int optname, char __user *optval,
> -		int __user *optlen)
> +int do_sock_getsockopt(struct socket *sock, bool compat, int level,
> +		       int optname, char __user *optval,
> +		       int __user *optlen)
>  {
>  	int max_optlen __maybe_unused;
>  	const struct proto_ops *ops;
> -	int err, fput_needed;
> -	struct socket *sock;
> -
> -	sock = sockfd_lookup_light(fd, &err, &fput_needed);
> -	if (!sock)
> -		return err;
> +	int err;
>  
>  	err = security_socket_getsockopt(sock, level, optname);
>  	if (err)
> -		goto out_put;
> -
> -	if (!in_compat_syscall())
> -		max_optlen = BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen);
> +		return err;
>  
>  	ops = READ_ONCE(sock->ops);
>  	if (level == SOL_SOCKET)
> @@ -2362,14 +2351,36 @@ int __sys_getsockopt(int fd, int level, int optname, char __user *optval,
>  	else if (unlikely(!ops->getsockopt))
>  		err = -EOPNOTSUPP;
>  	else
> -		err = ops->getsockopt(sock, level, optname, optval,
> -					    optlen);
> +		err = ops->getsockopt(sock, level, optname, optval, optlen);
>  
> -	if (!in_compat_syscall())
> +	if (!compat) {
> +		max_optlen = BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen);
>  		err = BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock->sk, level, optname,
>  						     optval, optlen, max_optlen,
>  						     err);
> -out_put:
> +	}
> +
> +	return err;
> +}
> +EXPORT_SYMBOL(do_sock_getsockopt);
> +
> +/*	Get a socket option. Because we don't know the option lengths we have
> + *	to pass a user mode parameter for the protocols to sort out.
> + */
> +int __sys_getsockopt(int fd, int level, int optname, char __user *optval,
> +		     int __user *optlen)
> +{
> +	int err, fput_needed;
> +	bool compat = in_compat_syscall();
> +	struct socket *sock;

Please respect the reverse x-mas tree order, thanks!

Paolo