linux-kernel - [PATCH v7 02/11] bpf: Add sockptr support for setsockopt

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Message-Id: <20231016134750.1381153-3-leitao@debian.org>
Date:   Mon, 16 Oct 2023 06:47:40 -0700
From:   Breno Leitao <leitao@...ian.org>
To:     sdf@...gle.com, axboe@...nel.dk, asml.silence@...il.com,
        willemdebruijn.kernel@...il.com, kuba@...nel.org,
        pabeni@...hat.com, martin.lau@...ux.dev, krisman@...e.de,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Song Liu <song@...nel.org>,
        Yonghong Song <yonghong.song@...ux.dev>,
        John Fastabend <john.fastabend@...il.com>,
        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>
Cc:     bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, io-uring@...r.kernel.org
Subject: [PATCH v7 02/11] bpf: Add sockptr support for setsockopt

The whole network stack uses sockptr, and while it doesn't move to
something more modern, let's use sockptr in setsockptr BPF hooks, so, it
could be used by other callers.

The main motivation for this change is to use it in the io_uring
{g,s}etsockopt(), which will use a userspace pointer for *optval, but, a
kernel value for optlen.

Link: https://lore.kernel.org/all/ZSArfLaaGcfd8LH8@gmail.com/

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 7b55844f6ba7..2912dce9144e 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -143,7 +143,7 @@ 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 97745f67ac15..491d20038cbe 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -1800,7 +1800,7 @@ 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);
@@ -1823,7 +1823,8 @@ 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 6b47dd499218..28d3eb339514 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2305,7 +2305,7 @@ 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