userns: Make seq_file's user namespace accessible
struct file already has a user namespace associated with it
in file->f_cred->user_ns, unfortunately because struct
seq_file has no struct file backpointer associated with
it, it is difficult to get at the user namespace in seq_file
context. Therefore add a helper function seq_user_ns to return
the associated user namespace and a user_ns field to struct
seq_file to be used in implementing seq_user_ns.
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index 83c44ee..68a04a3 100644
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -13,6 +13,7 @@
struct path;
struct inode;
struct dentry;
+struct user_namespace;
struct seq_file {
char *buf;
@@ -25,6 +26,9 @@
struct mutex lock;
const struct seq_operations *op;
int poll_event;
+#ifdef CONFIG_USER_NS
+ struct user_namespace *user_ns;
+#endif
void *private;
};
@@ -128,6 +132,16 @@
int seq_put_decimal_ll(struct seq_file *m, char delimiter,
long long num);
+static inline struct user_namespace *seq_user_ns(struct seq_file *seq)
+{
+#ifdef CONFIG_USER_NS
+ return seq->user_ns;
+#else
+ extern struct user_namespace init_user_ns;
+ return &init_user_ns;
+#endif
+}
+
#define SEQ_START_TOKEN ((void *)1)
/*
* Helpers for iteration over list_head-s in seq_files