Subject: [PATCH bpf-next v11 1/4] fs/nsfs.c: added ns_match

From: Carlos Neira <[email-masked]>
Date: Tue, 24 Sep 2019 12:20:02 -0300

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

Signed-off-by: Carlos Neira <[email-masked]>
---
 fs/nsfs.c               | 8 ++++++++
 include/linux/proc_ns.h | 2 ++
 2 files changed, 10 insertions(+)

diff --git a/fs/nsfs.c b/fs/nsfs.c
index a0431642c6b5..256f6295d33d 100644
--- a/fs/nsfs.c
+++ b/fs/nsfs.c
@@ -245,6 +245,14 @@ struct file *proc_ns_fget(int fd)
 	return ERR_PTR(-EINVAL);
 }
 
+/* Returns true if current namespace matches dev/ino.
+ */
+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);
diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h
index d31cb6215905..1da9f33489f3 100644
--- a/include/linux/proc_ns.h
+++ b/include/linux/proc_ns.h
@@ -82,6 +82,8 @@ typedef struct ns_common *ns_get_path_helper_t(void *);
 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);
-- 
2.20.1