linux/fs/notify/fdinfo.c
Dave Hansen 6933599697 inotify: hide internal kernel bits from fdinfo
There was a report that my patch:

    inotify: actually check for invalid bits in sys_inotify_add_watch()

broke CRIU.

The reason is that CRIU looks up raw flags in /proc/$pid/fdinfo/* to
figure out how to rebuild inotify watches and then passes those flags
directly back in to the inotify API.  One of those flags
(FS_EVENT_ON_CHILD) is set in mark->mask, but is not part of the inotify
API.  It is used inside the kernel to _implement_ inotify but it is not
and has never been part of the API.

My patch above ensured that we only allow bits which are part of the API
(IN_ALL_EVENTS).  This broke CRIU.

FS_EVENT_ON_CHILD is really internal to the kernel.  It is set _anyway_ on
all inotify marks.  So, CRIU was really just trying to set a bit that was
already set.

This patch hides that bit from fdinfo.  CRIU will not see the bit, not try
to set it, and should work as before.  We should not have been exposing
this bit in the first place, so this is a good patch independent of the
CRIU problem.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reported-by: Andrey Wagin <avagin@gmail.com>
Acked-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Eric Paris <eparis@redhat.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: John McCutchan <john@johnmccutchan.com>
Cc: Robert Love <rlove@rlove.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00

174 lines
4.3 KiB
C

#include <linux/file.h>
#include <linux/fs.h>
#include <linux/fsnotify_backend.h>
#include <linux/idr.h>
#include <linux/init.h>
#include <linux/inotify.h>
#include <linux/fanotify.h>
#include <linux/kernel.h>
#include <linux/namei.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/seq_file.h>
#include <linux/proc_fs.h>
#include <linux/exportfs.h>
#include "inotify/inotify.h"
#include "../fs/mount.h"
#if defined(CONFIG_PROC_FS)
#if defined(CONFIG_INOTIFY_USER) || defined(CONFIG_FANOTIFY)
static void show_fdinfo(struct seq_file *m, struct file *f,
void (*show)(struct seq_file *m,
struct fsnotify_mark *mark))
{
struct fsnotify_group *group = f->private_data;
struct fsnotify_mark *mark;
mutex_lock(&group->mark_mutex);
list_for_each_entry(mark, &group->marks_list, g_list) {
show(m, mark);
if (seq_has_overflowed(m))
break;
}
mutex_unlock(&group->mark_mutex);
}
#if defined(CONFIG_EXPORTFS)
static void show_mark_fhandle(struct seq_file *m, struct inode *inode)
{
struct {
struct file_handle handle;
u8 pad[MAX_HANDLE_SZ];
} f;
int size, ret, i;
f.handle.handle_bytes = sizeof(f.pad);
size = f.handle.handle_bytes >> 2;
ret = exportfs_encode_inode_fh(inode, (struct fid *)f.handle.f_handle, &size, 0);
if ((ret == FILEID_INVALID) || (ret < 0)) {
WARN_ONCE(1, "Can't encode file handler for inotify: %d\n", ret);
return;
}
f.handle.handle_type = ret;
f.handle.handle_bytes = size * sizeof(u32);
seq_printf(m, "fhandle-bytes:%x fhandle-type:%x f_handle:",
f.handle.handle_bytes, f.handle.handle_type);
for (i = 0; i < f.handle.handle_bytes; i++)
seq_printf(m, "%02x", (int)f.handle.f_handle[i]);
}
#else
static void show_mark_fhandle(struct seq_file *m, struct inode *inode)
{
}
#endif
#ifdef CONFIG_INOTIFY_USER
static void inotify_fdinfo(struct seq_file *m, struct fsnotify_mark *mark)
{
struct inotify_inode_mark *inode_mark;
struct inode *inode;
if (!(mark->flags & FSNOTIFY_MARK_FLAG_ALIVE) ||
!(mark->flags & FSNOTIFY_MARK_FLAG_INODE))
return;
inode_mark = container_of(mark, struct inotify_inode_mark, fsn_mark);
inode = igrab(mark->inode);
if (inode) {
/*
* IN_ALL_EVENTS represents all of the mask bits
* that we expose to userspace. There is at
* least one bit (FS_EVENT_ON_CHILD) which is
* used only internally to the kernel.
*/
u32 mask = mark->mask & IN_ALL_EVENTS;
seq_printf(m, "inotify wd:%x ino:%lx sdev:%x mask:%x ignored_mask:%x ",
inode_mark->wd, inode->i_ino, inode->i_sb->s_dev,
mask, mark->ignored_mask);
show_mark_fhandle(m, inode);
seq_putc(m, '\n');
iput(inode);
}
}
void inotify_show_fdinfo(struct seq_file *m, struct file *f)
{
show_fdinfo(m, f, inotify_fdinfo);
}
#endif /* CONFIG_INOTIFY_USER */
#ifdef CONFIG_FANOTIFY
static void fanotify_fdinfo(struct seq_file *m, struct fsnotify_mark *mark)
{
unsigned int mflags = 0;
struct inode *inode;
if (!(mark->flags & FSNOTIFY_MARK_FLAG_ALIVE))
return;
if (mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)
mflags |= FAN_MARK_IGNORED_SURV_MODIFY;
if (mark->flags & FSNOTIFY_MARK_FLAG_INODE) {
inode = igrab(mark->inode);
if (!inode)
return;
seq_printf(m, "fanotify ino:%lx sdev:%x mflags:%x mask:%x ignored_mask:%x ",
inode->i_ino, inode->i_sb->s_dev,
mflags, mark->mask, mark->ignored_mask);
show_mark_fhandle(m, inode);
seq_putc(m, '\n');
iput(inode);
} else if (mark->flags & FSNOTIFY_MARK_FLAG_VFSMOUNT) {
struct mount *mnt = real_mount(mark->mnt);
seq_printf(m, "fanotify mnt_id:%x mflags:%x mask:%x ignored_mask:%x\n",
mnt->mnt_id, mflags, mark->mask, mark->ignored_mask);
}
}
void fanotify_show_fdinfo(struct seq_file *m, struct file *f)
{
struct fsnotify_group *group = f->private_data;
unsigned int flags = 0;
switch (group->priority) {
case FS_PRIO_0:
flags |= FAN_CLASS_NOTIF;
break;
case FS_PRIO_1:
flags |= FAN_CLASS_CONTENT;
break;
case FS_PRIO_2:
flags |= FAN_CLASS_PRE_CONTENT;
break;
}
if (group->max_events == UINT_MAX)
flags |= FAN_UNLIMITED_QUEUE;
if (group->fanotify_data.max_marks == UINT_MAX)
flags |= FAN_UNLIMITED_MARKS;
seq_printf(m, "fanotify flags:%x event-flags:%x\n",
flags, group->fanotify_data.f_flags);
show_fdinfo(m, f, fanotify_fdinfo);
}
#endif /* CONFIG_FANOTIFY */
#endif /* CONFIG_INOTIFY_USER || CONFIG_FANOTIFY */
#endif /* CONFIG_PROC_FS */