kernel-aes67/include/linux/proc_fs.h
Eric W. Biederman 077130c0cf [NET]: Fix race when opening a proc file while a network namespace is exiting.
The problem:  proc_net files remember which network namespace the are
against but do not remember hold a reference count (as that would pin
the network namespace).   So we currently have a small window where
the reference count on a network namespace may be incremented when opening
a /proc file when it has already gone to zero.

To fix this introduce maybe_get_net and get_proc_net.

maybe_get_net increments the network namespace reference count only if it is
greater then zero, ensuring we don't increment a reference count after it
has gone to zero.

get_proc_net handles all of the magic to go from a proc inode to the network
namespace instance and call maybe_get_net on it.

PROC_NET the old accessor is removed so that we don't get confused and use
the wrong helper function.

Then I fix up the callers to use get_proc_net and handle the case case
where get_proc_net returns NULL.  In that case I return -ENXIO because
effectively the network namespace has already gone away so the files
we are trying to access don't exist anymore.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:49:22 -07:00

284 lines
8.4 KiB
C

#ifndef _LINUX_PROC_FS_H
#define _LINUX_PROC_FS_H
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/spinlock.h>
#include <linux/magic.h>
#include <asm/atomic.h>
struct net;
struct completion;
/*
* The proc filesystem constants/structures
*/
/*
* Offset of the first process in the /proc root directory..
*/
#define FIRST_PROCESS_ENTRY 256
/*
* We always define these enumerators
*/
enum {
PROC_ROOT_INO = 1,
};
/*
* This is not completely implemented yet. The idea is to
* create an in-memory tree (like the actual /proc filesystem
* tree) of these proc_dir_entries, so that we can dynamically
* add new files to /proc.
*
* The "next" pointer creates a linked list of one /proc directory,
* while parent/subdir create the directory structure (every
* /proc file has a parent, but "subdir" is NULL for all
* non-directory entries).
*
* "get_info" is called at "read", while "owner" is used to protect module
* from unloading while proc_dir_entry is in use
*/
typedef int (read_proc_t)(char *page, char **start, off_t off,
int count, int *eof, void *data);
typedef int (write_proc_t)(struct file *file, const char __user *buffer,
unsigned long count, void *data);
typedef int (get_info_t)(char *, char **, off_t, int);
struct proc_dir_entry {
unsigned int low_ino;
unsigned short namelen;
const char *name;
mode_t mode;
nlink_t nlink;
uid_t uid;
gid_t gid;
loff_t size;
const struct inode_operations *proc_iops;
/*
* NULL ->proc_fops means "PDE is going away RSN" or
* "PDE is just created". In either case, e.g. ->read_proc won't be
* called because it's too late or too early, respectively.
*
* If you're allocating ->proc_fops dynamically, save a pointer
* somewhere.
*/
const struct file_operations *proc_fops;
get_info_t *get_info;
struct module *owner;
struct proc_dir_entry *next, *parent, *subdir;
void *data;
read_proc_t *read_proc;
write_proc_t *write_proc;
atomic_t count; /* use count */
int deleted; /* delete flag */
int pde_users; /* number of callers into module in progress */
spinlock_t pde_unload_lock; /* proc_fops checks and pde_users bumps */
struct completion *pde_unload_completion;
};
struct kcore_list {
struct kcore_list *next;
unsigned long addr;
size_t size;
};
struct vmcore {
struct list_head list;
unsigned long long paddr;
unsigned long long size;
loff_t offset;
};
#ifdef CONFIG_PROC_FS
extern struct proc_dir_entry proc_root;
extern struct proc_dir_entry *proc_root_fs;
extern struct proc_dir_entry *proc_bus;
extern struct proc_dir_entry *proc_root_driver;
extern struct proc_dir_entry *proc_root_kcore;
extern spinlock_t proc_subdir_lock;
extern void proc_root_init(void);
extern void proc_misc_init(void);
struct mm_struct;
void proc_flush_task(struct task_struct *task);
struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *);
int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir);
unsigned long task_vsize(struct mm_struct *);
int task_statm(struct mm_struct *, int *, int *, int *, int *);
char *task_mem(struct mm_struct *, char *);
void clear_refs_smap(struct mm_struct *mm);
struct proc_dir_entry *de_get(struct proc_dir_entry *de);
void de_put(struct proc_dir_entry *de);
extern struct proc_dir_entry *create_proc_entry(const char *name, mode_t mode,
struct proc_dir_entry *parent);
extern void remove_proc_entry(const char *name, struct proc_dir_entry *parent);
extern struct vfsmount *proc_mnt;
extern int proc_fill_super(struct super_block *,void *,int);
extern struct inode *proc_get_inode(struct super_block *, unsigned int, struct proc_dir_entry *);
/*
* These are generic /proc routines that use the internal
* "struct proc_dir_entry" tree to traverse the filesystem.
*
* The /proc root directory has extended versions to take care
* of the /proc/<pid> subdirectories.
*/
extern int proc_readdir(struct file *, void *, filldir_t);
extern struct dentry *proc_lookup(struct inode *, struct dentry *, struct nameidata *);
extern const struct file_operations proc_kcore_operations;
extern const struct file_operations proc_kmsg_operations;
extern const struct file_operations ppc_htab_operations;
/*
* proc_tty.c
*/
struct tty_driver;
extern void proc_tty_init(void);
extern void proc_tty_register_driver(struct tty_driver *driver);
extern void proc_tty_unregister_driver(struct tty_driver *driver);
/*
* proc_devtree.c
*/
#ifdef CONFIG_PROC_DEVICETREE
struct device_node;
struct property;
extern void proc_device_tree_init(void);
extern void proc_device_tree_add_node(struct device_node *, struct proc_dir_entry *);
extern void proc_device_tree_add_prop(struct proc_dir_entry *pde, struct property *prop);
extern void proc_device_tree_remove_prop(struct proc_dir_entry *pde,
struct property *prop);
extern void proc_device_tree_update_prop(struct proc_dir_entry *pde,
struct property *newprop,
struct property *oldprop);
#endif /* CONFIG_PROC_DEVICETREE */
extern struct proc_dir_entry *proc_symlink(const char *,
struct proc_dir_entry *, const char *);
extern struct proc_dir_entry *proc_mkdir(const char *,struct proc_dir_entry *);
extern struct proc_dir_entry *proc_mkdir_mode(const char *name, mode_t mode,
struct proc_dir_entry *parent);
static inline struct proc_dir_entry *create_proc_read_entry(const char *name,
mode_t mode, struct proc_dir_entry *base,
read_proc_t *read_proc, void * data)
{
struct proc_dir_entry *res=create_proc_entry(name,mode,base);
if (res) {
res->read_proc=read_proc;
res->data=data;
}
return res;
}
static inline struct proc_dir_entry *create_proc_info_entry(const char *name,
mode_t mode, struct proc_dir_entry *base, get_info_t *get_info)
{
struct proc_dir_entry *res=create_proc_entry(name,mode,base);
if (res) res->get_info=get_info;
return res;
}
extern struct proc_dir_entry *proc_net_create(struct net *net,
const char *name, mode_t mode, get_info_t *get_info);
extern struct proc_dir_entry *proc_net_fops_create(struct net *net,
const char *name, mode_t mode, const struct file_operations *fops);
extern void proc_net_remove(struct net *net, const char *name);
#else
#define proc_root_driver NULL
#define proc_bus NULL
#define proc_net_fops_create(net, name, mode, fops) ({ (void)(mode), NULL; })
#define proc_net_create(net, name, mode, info) ({ (void)(mode), NULL; })
static inline void proc_net_remove(struct net *net, const char *name) {}
static inline void proc_flush_task(struct task_struct *task) { }
static inline struct proc_dir_entry *create_proc_entry(const char *name,
mode_t mode, struct proc_dir_entry *parent) { return NULL; }
#define remove_proc_entry(name, parent) do {} while (0)
static inline struct proc_dir_entry *proc_symlink(const char *name,
struct proc_dir_entry *parent,const char *dest) {return NULL;}
static inline struct proc_dir_entry *proc_mkdir(const char *name,
struct proc_dir_entry *parent) {return NULL;}
static inline struct proc_dir_entry *create_proc_read_entry(const char *name,
mode_t mode, struct proc_dir_entry *base,
read_proc_t *read_proc, void * data) { return NULL; }
static inline struct proc_dir_entry *create_proc_info_entry(const char *name,
mode_t mode, struct proc_dir_entry *base, get_info_t *get_info)
{ return NULL; }
struct tty_driver;
static inline void proc_tty_register_driver(struct tty_driver *driver) {};
static inline void proc_tty_unregister_driver(struct tty_driver *driver) {};
extern struct proc_dir_entry proc_root;
#endif /* CONFIG_PROC_FS */
#if !defined(CONFIG_PROC_KCORE)
static inline void kclist_add(struct kcore_list *new, void *addr, size_t size)
{
}
#else
extern void kclist_add(struct kcore_list *, void *, size_t);
#endif
union proc_op {
int (*proc_get_link)(struct inode *, struct dentry **, struct vfsmount **);
int (*proc_read)(struct task_struct *task, char *page);
};
struct proc_inode {
struct pid *pid;
int fd;
union proc_op op;
struct proc_dir_entry *pde;
struct inode vfs_inode;
};
static inline struct proc_inode *PROC_I(const struct inode *inode)
{
return container_of(inode, struct proc_inode, vfs_inode);
}
static inline struct proc_dir_entry *PDE(const struct inode *inode)
{
return PROC_I(inode)->pde;
}
static inline struct net *PDE_NET(struct proc_dir_entry *pde)
{
return pde->parent->data;
}
struct net *get_proc_net(const struct inode *inode);
struct proc_maps_private {
struct pid *pid;
struct task_struct *task;
#ifdef CONFIG_MMU
struct vm_area_struct *tail_vma;
#endif
};
#endif /* _LINUX_PROC_FS_H */