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Commit adb37c4c authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

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: default avatarDavid S. Miller <davem@davemloft.net>
Acked-by: default avatarSerge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
parent fc5795c8

fs/seq_file.c

+4 −0
Original line number Diff line number Diff line
@@ -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

include/linux/seq_file.h

+14 −0
Original line number Diff line number Diff line
@@ -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