From: Carlos Neira <cneirabustos@gmail.com>
Date: Wed, 4 Mar 2020 17:41:55 -0300
Subject: fs/nsfs.c: Added ns_match
Patch-mainline: v5.7-rc1
Git-commit: 1e2328e762548c7d17b7ba8ded9f409d05710dd1
References: bsc#1177028

ns_match returns true if the namespace inode and dev_t matches the ones
provided by the caller.

Signed-off-by: Carlos Neira <cneirabustos@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200304204157.58695-2-cneirabustos@gmail.com
Acked-by: Gary Lin <glin@suse.com>
---
 fs/nsfs.c               |   14 ++++++++++++++
 include/linux/proc_ns.h |    2 ++
 2 files changed, 16 insertions(+)

--- a/fs/nsfs.c
+++ b/fs/nsfs.c
@@ -245,6 +245,20 @@ out_invalid:
 	return ERR_PTR(-EINVAL);
 }
 
+/**
+ * ns_match() - Returns true if current namespace matches dev/ino provided.
+ * @ns_common: current ns
+ * @dev: dev_t from nsfs that will be matched against current nsfs
+ * @ino: ino_t from nsfs that will be matched against current nsfs
+ *
+ * Return: true if dev and ino matches the current nsfs.
+ */
+bool ns_match(const struct ns_common *ns, dev_t dev, ino_t ino)
+{
+	return (ns->inum == ino) && (nsfs_mnt->mnt_sb->s_dev == dev);
+}
+
+
 static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry)
 {
 	struct inode *inode = d_inode(dentry);
--- a/include/linux/proc_ns.h
+++ b/include/linux/proc_ns.h
@@ -85,6 +85,8 @@ typedef struct ns_common *ns_get_path_he
 extern void *ns_get_path_cb(struct path *path, ns_get_path_helper_t ns_get_cb,
 			    void *private_data);
 
+extern bool ns_match(const struct ns_common *ns, dev_t dev, ino_t ino);
+
 extern int ns_get_name(char *buf, size_t size, struct task_struct *task,
 			const struct proc_ns_operations *ns_ops);
 extern void nsfs_init(void);