linux-kernel - [PATCH v4 02/10] bpf: Leverage sockptr

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Date:   Mon,  4 Sep 2023 09:24:55 -0700
From:   Breno Leitao <leitao@...ian.org>
To:     sdf@...gle.com, axboe@...nel.dk, asml.silence@...il.com,
        willemdebruijn.kernel@...il.com, martin.lau@...ux.dev,
        krisman@...e.de, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        John Fastabend <john.fastabend@...il.com>,
        Andrii Nakryiko <andrii@...nel.org>,
        Song Liu <song@...nel.org>,
        Yonghong Song <yonghong.song@...ux.dev>,
        KP Singh <kpsingh@...nel.org>, Hao Luo <haoluo@...gle.com>,
        Jiri Olsa <jolsa@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, io-uring@...r.kernel.org
Subject: [PATCH v4 02/10] bpf: Leverage sockptr_t in BPF setsockopt hook

Change BPF setsockopt hook (__cgroup_bpf_run_filter_setsockopt()) to use
sockptr instead of user pointers. This brings flexibility to the
function, since it could be called with userspace or kernel pointers.

This change will allow the creation of a core sock_setsockopt, called
do_sock_setsockopt(), which will be called from both the system call path
and by io_uring command.

This also aligns with the getsockopt() counterpart, which is now using
sockptr_t universal pointer.

Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 include/linux/bpf-cgroup.h | 2 +-
 kernel/bpf/cgroup.c        | 5 +++--
 net/socket.c               | 2 +-
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index f5b4fb6ed8c6..cecfe8c99f28 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -137,7 +137,7 @@ int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
 				   enum cgroup_bpf_attach_type atype);
 
 int __cgroup_bpf_run_filter_setsockopt(struct sock *sock, int *level,
-				       int *optname, char __user *optval,
+				       int *optname, sockptr_t optval,
 				       int *optlen, char **kernel_optval);
 
 int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index ebc8c58f7e46..f0dedd4f7f2e 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -1785,7 +1785,7 @@ static bool sockopt_buf_allocated(struct bpf_sockopt_kern *ctx,
 }
 
 int __cgroup_bpf_run_filter_setsockopt(struct sock *sk, int *level,
-				       int *optname, char __user *optval,
+				       int *optname, sockptr_t optval,
 				       int *optlen, char **kernel_optval)
 {
 	struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
@@ -1808,7 +1808,8 @@ int __cgroup_bpf_run_filter_setsockopt(struct sock *sk, int *level,
 
 	ctx.optlen = *optlen;
 
-	if (copy_from_user(ctx.optval, optval, min(*optlen, max_optlen)) != 0) {
+	if (copy_from_sockptr(ctx.optval, optval,
+			      min(*optlen, max_optlen))) {
 		ret = -EFAULT;
 		goto out;
 	}
diff --git a/net/socket.c b/net/socket.c
index 6fda5d011521..9ec9a8a07c0e 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2287,7 +2287,7 @@ int __sys_setsockopt(int fd, int level, int optname, char __user *user_optval,
 
 	if (!in_compat_syscall())
 		err = BPF_CGROUP_RUN_PROG_SETSOCKOPT(sock->sk, &level, &optname,
-						     user_optval, &optlen,
+						     optval, &optlen,
 						     &kernel_optval);
 	if (err < 0)
 		goto out_put;
-- 
2.34.1