From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxx>
Cc: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Acked-by: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx>
Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
---
fs/seq_file.c | 4 ++++
include/linux/seq_file.h | 14 ++++++++++++++
2 files changed, 18 insertions(+), 0 deletions(-)
diff --git a/fs/seq_file.c b/fs/seq_file.c
index 14cf9de..99dffab 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -9,6 +9,7 @@
#include <linux/export.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
+#include <linux/cred.h>
#include <asm/uaccess.h>
#include <asm/page.h>
@@ -56,6 +57,9 @@ int seq_open(struct file *file, const struct seq_operations *op)
memset(p, 0, sizeof(*p));
mutex_init(&p->lock);
p->op = op;
+#ifdef CONFIG_USER_NS
+ p->user_ns = file->f_cred->user_ns;
+#endif
/*
* Wrappers around seq_open(e.g. swaps_open) need to be
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 file;
struct path;
struct inode;
struct dentry;
+struct user_namespace;
struct seq_file {
char *buf;
@@ -25,6 +26,9 @@ struct seq_file {
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_ull(struct seq_file *m, char delimiter,
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
--
1.7.5.4
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