linux_dsm_epyc7002/fs/proc/internal.h
Eric W. Biederman 2fd1d2c4ce proc: Fix proc_sys_prune_dcache to hold a sb reference
Andrei Vagin writes:
FYI: This bug has been reproduced on 4.11.7
> BUG: Dentry ffff895a3dd01240{i=4e7c09a,n=lo}  still in use (1) [unmount of proc proc]
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 13588 at fs/dcache.c:1445 umount_check+0x6e/0x80
> CPU: 1 PID: 13588 Comm: kworker/1:1 Not tainted 4.11.7-200.fc25.x86_64 #1
> Hardware name: CompuLab sbc-flt1/fitlet, BIOS SBCFLT_0.08.04 06/27/2015
> Workqueue: events proc_cleanup_work
> Call Trace:
>  dump_stack+0x63/0x86
>  __warn+0xcb/0xf0
>  warn_slowpath_null+0x1d/0x20
>  umount_check+0x6e/0x80
>  d_walk+0xc6/0x270
>  ? dentry_free+0x80/0x80
>  do_one_tree+0x26/0x40
>  shrink_dcache_for_umount+0x2d/0x90
>  generic_shutdown_super+0x1f/0xf0
>  kill_anon_super+0x12/0x20
>  proc_kill_sb+0x40/0x50
>  deactivate_locked_super+0x43/0x70
>  deactivate_super+0x5a/0x60
>  cleanup_mnt+0x3f/0x90
>  mntput_no_expire+0x13b/0x190
>  kern_unmount+0x3e/0x50
>  pid_ns_release_proc+0x15/0x20
>  proc_cleanup_work+0x15/0x20
>  process_one_work+0x197/0x450
>  worker_thread+0x4e/0x4a0
>  kthread+0x109/0x140
>  ? process_one_work+0x450/0x450
>  ? kthread_park+0x90/0x90
>  ret_from_fork+0x2c/0x40
> ---[ end trace e1c109611e5d0b41 ]---
> VFS: Busy inodes after unmount of proc. Self-destruct in 5 seconds.  Have a nice day...
> BUG: unable to handle kernel NULL pointer dereference at           (null)
> IP: _raw_spin_lock+0xc/0x30
> PGD 0

Fix this by taking a reference to the super block in proc_sys_prune_dcache.

The superblock reference is the core of the fix however the sysctl_inodes
list is converted to a hlist so that hlist_del_init_rcu may be used.  This
allows proc_sys_prune_dache to remove inodes the sysctl_inodes list, while
not causing problems for proc_sys_evict_inode when if it later choses to
remove the inode from the sysctl_inodes list.  Removing inodes from the
sysctl_inodes list allows proc_sys_prune_dcache to have a progress
guarantee, while still being able to drop all locks.  The fact that
head->unregistering is set in start_unregistering ensures that no more
inodes will be added to the the sysctl_inodes list.

Previously the code did a dance where it delayed calling iput until the
next entry in the list was being considered to ensure the inode remained on
the sysctl_inodes list until the next entry was walked to.  The structure
of the loop in this patch does not need that so is much easier to
understand and maintain.

Cc: stable@vger.kernel.org
Reported-by: Andrei Vagin <avagin@gmail.com>
Tested-by: Andrei Vagin <avagin@openvz.org>
Fixes: ace0c791e6 ("proc/sysctl: Don't grab i_lock under sysctl_lock.")
Fixes: d6cffbbe9a ("proc/sysctl: prune stale dentries during unregistering")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-07-11 11:01:24 -05:00

300 lines
8.2 KiB
C

/* Internal procfs definitions
*
* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/proc_fs.h>
#include <linux/proc_ns.h>
#include <linux/spinlock.h>
#include <linux/atomic.h>
#include <linux/binfmts.h>
#include <linux/sched/coredump.h>
#include <linux/sched/task.h>
struct ctl_table_header;
struct mempolicy;
/*
* 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.
*
* parent/subdir are used for the directory structure (every /proc file has a
* parent, but "subdir" is empty for all non-directory entries).
* subdir_node is used to build the rb tree "subdir" of the parent.
*/
struct proc_dir_entry {
unsigned int low_ino;
umode_t mode;
nlink_t nlink;
kuid_t uid;
kgid_t gid;
loff_t size;
const struct inode_operations *proc_iops;
const struct file_operations *proc_fops;
struct proc_dir_entry *parent;
struct rb_root subdir;
struct rb_node subdir_node;
void *data;
atomic_t count; /* use count */
atomic_t in_use; /* number of callers into module in progress; */
/* negative -> it's going away RSN */
struct completion *pde_unload_completion;
struct list_head pde_openers; /* who did ->open, but not ->release */
spinlock_t pde_unload_lock; /* proc_fops checks and pde_users bumps */
u8 namelen;
char name[];
};
union proc_op {
int (*proc_get_link)(struct dentry *, struct path *);
int (*proc_show)(struct seq_file *m,
struct pid_namespace *ns, struct pid *pid,
struct task_struct *task);
};
struct proc_inode {
struct pid *pid;
unsigned int fd;
union proc_op op;
struct proc_dir_entry *pde;
struct ctl_table_header *sysctl;
struct ctl_table *sysctl_entry;
struct hlist_node sysctl_inodes;
const struct proc_ns_operations *ns_ops;
struct inode vfs_inode;
};
/*
* General functions
*/
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 void *__PDE_DATA(const struct inode *inode)
{
return PDE(inode)->data;
}
static inline struct pid *proc_pid(struct inode *inode)
{
return PROC_I(inode)->pid;
}
static inline struct task_struct *get_proc_task(struct inode *inode)
{
return get_pid_task(proc_pid(inode), PIDTYPE_PID);
}
void task_dump_owner(struct task_struct *task, mode_t mode,
kuid_t *ruid, kgid_t *rgid);
static inline unsigned name_to_int(const struct qstr *qstr)
{
const char *name = qstr->name;
int len = qstr->len;
unsigned n = 0;
if (len > 1 && *name == '0')
goto out;
while (len-- > 0) {
unsigned c = *name++ - '0';
if (c > 9)
goto out;
if (n >= (~0U-9)/10)
goto out;
n *= 10;
n += c;
}
return n;
out:
return ~0U;
}
/*
* Offset of the first process in the /proc root directory..
*/
#define FIRST_PROCESS_ENTRY 256
/* Worst case buffer size needed for holding an integer. */
#define PROC_NUMBUF 13
/*
* array.c
*/
extern const struct file_operations proc_tid_children_operations;
extern int proc_tid_stat(struct seq_file *, struct pid_namespace *,
struct pid *, struct task_struct *);
extern int proc_tgid_stat(struct seq_file *, struct pid_namespace *,
struct pid *, struct task_struct *);
extern int proc_pid_status(struct seq_file *, struct pid_namespace *,
struct pid *, struct task_struct *);
extern int proc_pid_statm(struct seq_file *, struct pid_namespace *,
struct pid *, struct task_struct *);
/*
* base.c
*/
extern const struct dentry_operations pid_dentry_operations;
extern int pid_getattr(const struct path *, struct kstat *, u32, unsigned int);
extern int proc_setattr(struct dentry *, struct iattr *);
extern struct inode *proc_pid_make_inode(struct super_block *, struct task_struct *, umode_t);
extern int pid_revalidate(struct dentry *, unsigned int);
extern int pid_delete_dentry(const struct dentry *);
extern int proc_pid_readdir(struct file *, struct dir_context *);
extern struct dentry *proc_pid_lookup(struct inode *, struct dentry *, unsigned int);
extern loff_t mem_lseek(struct file *, loff_t, int);
/* Lookups */
typedef int instantiate_t(struct inode *, struct dentry *,
struct task_struct *, const void *);
extern bool proc_fill_cache(struct file *, struct dir_context *, const char *, int,
instantiate_t, struct task_struct *, const void *);
/*
* generic.c
*/
extern struct dentry *proc_lookup(struct inode *, struct dentry *, unsigned int);
extern struct dentry *proc_lookup_de(struct proc_dir_entry *, struct inode *,
struct dentry *);
extern int proc_readdir(struct file *, struct dir_context *);
extern int proc_readdir_de(struct proc_dir_entry *, struct file *, struct dir_context *);
static inline struct proc_dir_entry *pde_get(struct proc_dir_entry *pde)
{
atomic_inc(&pde->count);
return pde;
}
extern void pde_put(struct proc_dir_entry *);
static inline bool is_empty_pde(const struct proc_dir_entry *pde)
{
return S_ISDIR(pde->mode) && !pde->proc_iops;
}
/*
* inode.c
*/
struct pde_opener {
struct file *file;
struct list_head lh;
bool closing;
struct completion *c;
};
extern const struct inode_operations proc_link_inode_operations;
extern const struct inode_operations proc_pid_link_inode_operations;
extern void proc_init_inodecache(void);
void set_proc_pid_nlink(void);
extern struct inode *proc_get_inode(struct super_block *, struct proc_dir_entry *);
extern int proc_fill_super(struct super_block *, void *data, int flags);
extern void proc_entry_rundown(struct proc_dir_entry *);
/*
* proc_namespaces.c
*/
extern const struct inode_operations proc_ns_dir_inode_operations;
extern const struct file_operations proc_ns_dir_operations;
/*
* proc_net.c
*/
extern const struct file_operations proc_net_operations;
extern const struct inode_operations proc_net_inode_operations;
#ifdef CONFIG_NET
extern int proc_net_init(void);
#else
static inline int proc_net_init(void) { return 0; }
#endif
/*
* proc_self.c
*/
extern int proc_setup_self(struct super_block *);
/*
* proc_thread_self.c
*/
extern int proc_setup_thread_self(struct super_block *);
extern void proc_thread_self_init(void);
/*
* proc_sysctl.c
*/
#ifdef CONFIG_PROC_SYSCTL
extern int proc_sys_init(void);
extern void proc_sys_evict_inode(struct inode *inode,
struct ctl_table_header *head);
#else
static inline void proc_sys_init(void) { }
static inline void proc_sys_evict_inode(struct inode *inode,
struct ctl_table_header *head) { }
#endif
/*
* proc_tty.c
*/
#ifdef CONFIG_TTY
extern void proc_tty_init(void);
#else
static inline void proc_tty_init(void) {}
#endif
/*
* root.c
*/
extern struct proc_dir_entry proc_root;
extern int proc_parse_options(char *options, struct pid_namespace *pid);
extern void proc_self_init(void);
extern int proc_remount(struct super_block *, int *, char *);
/*
* task_[no]mmu.c
*/
struct proc_maps_private {
struct inode *inode;
struct task_struct *task;
struct mm_struct *mm;
#ifdef CONFIG_MMU
struct vm_area_struct *tail_vma;
#endif
#ifdef CONFIG_NUMA
struct mempolicy *task_mempolicy;
#endif
};
struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode);
extern const struct file_operations proc_pid_maps_operations;
extern const struct file_operations proc_tid_maps_operations;
extern const struct file_operations proc_pid_numa_maps_operations;
extern const struct file_operations proc_tid_numa_maps_operations;
extern const struct file_operations proc_pid_smaps_operations;
extern const struct file_operations proc_tid_smaps_operations;
extern const struct file_operations proc_clear_refs_operations;
extern const struct file_operations proc_pagemap_operations;
extern unsigned long task_vsize(struct mm_struct *);
extern unsigned long task_statm(struct mm_struct *,
unsigned long *, unsigned long *,
unsigned long *, unsigned long *);
extern void task_mem(struct seq_file *, struct mm_struct *);