[Devel] [PATCH RHEL8 COMMIT] ms/net: Allow to show socket-specific information in /proc/[pid]/fdinfo/[fd]

[Konstantin Khorenko]

The commit is pushed to "branch-rh8-4.18.0-240.1.1.vz8.5.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-240.1.1.vz8.5.34
------>
commit f4220f231d22ece06b3bdc8cde3121bdbec098dd
Author: Vasily Averin <vvs at virtuozzo.com>
Date:   Wed Jun 2 19:47:59 2021 +0300

    ms/net: Allow to show socket-specific information in /proc/[pid]/fdinfo/[fd]
    
    This adds .show_fdinfo to socket_file_ops, so protocols will be able
    to print their specific data in fdinfo.
    
    Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
    Signed-off-by: David S. Miller <davem at davemloft.net>
    
    (cherry picked from ms commit b4653342b151 ("net: Allow to show socket-specific
    information in /proc/[pid]/fdinfo/[fd]"))
    
    VvS: taken from vz7 commit 27e26a1cb241 ("ms/net: Allow to show socket-specific
    information in /proc/[pid]/fdinfo/[fd]")
    
    Signed-off-by: Vasily Averin <vvs at virtuozzo.com>
---
 include/linux/net.h |  1 +
 net/socket.c        | 12 ++++++++++++
 2 files changed, 13 insertions(+)

diff --git a/include/linux/net.h b/include/linux/net.h
index 8a19d8d84a02..df3f79a8e753 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -178,6 +178,7 @@ struct proto_ops {
 	int		(*compat_getsockopt)(struct socket *sock, int level,
 				      int optname, char __user *optval, int __user *optlen);
 #endif
+	void		(*show_fdinfo)(struct seq_file *m, struct socket *sock);
 	int		(*sendmsg)   (struct socket *sock, struct msghdr *m,
 				      size_t total_len);
 	/* Notes for implementing recvmsg:
diff --git a/net/socket.c b/net/socket.c
index fcd82cf86c0c..bbd3c9dd2b1d 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -140,6 +140,7 @@ static ssize_t sock_sendpage(struct file *file, struct page *page,
 static ssize_t sock_splice_read(struct file *file, loff_t *ppos,
 				struct pipe_inode_info *pipe, size_t len,
 				unsigned int flags);
+static void sock_show_fdinfo(struct seq_file *m, struct file *f);
 
 /*
  *	Socket files have a set of 'special' operations as well as the generic file ones. These don't appear
@@ -162,6 +163,9 @@ static const struct file_operations socket_file_ops = {
 	.sendpage =	sock_sendpage,
 	.splice_write = generic_splice_sendpage,
 	.splice_read =	sock_splice_read,
+#ifdef CONFIG_PROC_FS
+	.show_fdinfo =	sock_show_fdinfo,
+#endif
 };
 
 /*
@@ -986,6 +990,14 @@ static ssize_t sock_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	return res;
 }
 
+static void sock_show_fdinfo(struct seq_file *m, struct file *f)
+{
+	struct socket *sock = f->private_data;
+
+	if (sock->ops->show_fdinfo)
+		sock->ops->show_fdinfo(m, sock);
+}
+
 /*
  * Atomic setting of ioctl hooks to avoid race
  * with module unload.