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Date: Mon, 2 Jun 2014 20:03:42 +0200
From: Heinrich Schuchardt <xypron.glpk@....de>
To: John McCutchan <john@...nmccutchan.com>,
Robert Love <rlove@...ve.org>,
Eric Paris <eparis@...isplace.org>
Cc: Jan Kara <jack@...e.cz>, Michael Kerrisk <mtk.manpages@...il.com>,
linux-kernel@...r.kernel.org,
Heinrich Schuchardt <xypron.glpk@....de>
Subject: [PATCH 1/1] inotify: bug 77111 - fix reusage of watch descriptors
Without the patch inotify watch descriptors may be reused by
inotify_add_watch before all events for the previous usage
of the watch descriptor have been read.
With the patch watch descriptors are removed from the idr only
after the IN_IGNORED event has been read.
The sequence of some static routines is rearranged.
The significant change moving the call of
inotify_remove_from_idr form inotify_ignored_and_remove_idr to
to copy_event_to_user and renaming inotify_ignored_and_remove_idr
to inotify_ignored.
cf.
https://bugzilla.kernel.org/show_bug.cgi?id=77111
Signed-off-by: Heinrich Schuchardt <xypron.glpk@....de>
---
fs/notify/inotify/inotify.h | 4 +-
fs/notify/inotify/inotify_fsnotify.c | 2 +-
fs/notify/inotify/inotify_user.c | 257 ++++++++++++++++++-----------------
3 files changed, 135 insertions(+), 128 deletions(-)
diff --git a/fs/notify/inotify/inotify.h b/fs/notify/inotify/inotify.h
index ed855ef..596c513 100644
--- a/fs/notify/inotify/inotify.h
+++ b/fs/notify/inotify/inotify.h
@@ -20,8 +20,8 @@ static inline struct inotify_event_info *INOTIFY_E(struct fsnotify_event *fse)
return container_of(fse, struct inotify_event_info, fse);
}
-extern void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark,
- struct fsnotify_group *group);
+extern void inotify_ignored(struct fsnotify_mark *fsn_mark,
+ struct fsnotify_group *group);
extern int inotify_handle_event(struct fsnotify_group *group,
struct inode *inode,
struct fsnotify_mark *inode_mark,
diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c
index 43ab1e1..68729dd 100644
--- a/fs/notify/inotify/inotify_fsnotify.c
+++ b/fs/notify/inotify/inotify_fsnotify.c
@@ -122,7 +122,7 @@ int inotify_handle_event(struct fsnotify_group *group,
static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
{
- inotify_ignored_and_remove_idr(fsn_mark, group);
+ inotify_ignored(fsn_mark, group);
}
/*
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index 78a2ca3..7a354b0 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -164,115 +164,6 @@ static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
return event;
}
-/*
- * Copy an event to user space, returning how much we copied.
- *
- * We already checked that the event size is smaller than the
- * buffer we had in "get_one_event()" above.
- */
-static ssize_t copy_event_to_user(struct fsnotify_group *group,
- struct fsnotify_event *fsn_event,
- char __user *buf)
-{
- struct inotify_event inotify_event;
- struct inotify_event_info *event;
- size_t event_size = sizeof(struct inotify_event);
- size_t name_len;
- size_t pad_name_len;
-
- pr_debug("%s: group=%p event=%p\n", __func__, group, fsn_event);
-
- event = INOTIFY_E(fsn_event);
- name_len = event->name_len;
- /*
- * round up name length so it is a multiple of event_size
- * plus an extra byte for the terminating '\0'.
- */
- pad_name_len = round_event_name_len(fsn_event);
- inotify_event.len = pad_name_len;
- inotify_event.mask = inotify_mask_to_arg(fsn_event->mask);
- inotify_event.wd = event->wd;
- inotify_event.cookie = event->sync_cookie;
-
- /* send the main event */
- if (copy_to_user(buf, &inotify_event, event_size))
- return -EFAULT;
-
- buf += event_size;
-
- /*
- * fsnotify only stores the pathname, so here we have to send the pathname
- * and then pad that pathname out to a multiple of sizeof(inotify_event)
- * with zeros.
- */
- if (pad_name_len) {
- /* copy the path name */
- if (copy_to_user(buf, event->name, name_len))
- return -EFAULT;
- buf += name_len;
-
- /* fill userspace with 0's */
- if (clear_user(buf, pad_name_len - name_len))
- return -EFAULT;
- event_size += pad_name_len;
- }
-
- return event_size;
-}
-
-static ssize_t inotify_read(struct file *file, char __user *buf,
- size_t count, loff_t *pos)
-{
- struct fsnotify_group *group;
- struct fsnotify_event *kevent;
- char __user *start;
- int ret;
- DEFINE_WAIT(wait);
-
- start = buf;
- group = file->private_data;
-
- while (1) {
- prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE);
-
- mutex_lock(&group->notification_mutex);
- kevent = get_one_event(group, count);
- mutex_unlock(&group->notification_mutex);
-
- pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent);
-
- if (kevent) {
- ret = PTR_ERR(kevent);
- if (IS_ERR(kevent))
- break;
- ret = copy_event_to_user(group, kevent, buf);
- fsnotify_destroy_event(group, kevent);
- if (ret < 0)
- break;
- buf += ret;
- count -= ret;
- continue;
- }
-
- ret = -EAGAIN;
- if (file->f_flags & O_NONBLOCK)
- break;
- ret = -ERESTARTSYS;
- if (signal_pending(current))
- break;
-
- if (start != buf)
- break;
-
- schedule();
- }
-
- finish_wait(&group->notification_waitq, &wait);
- if (start != buf && ret != -EFAULT)
- ret = buf - start;
- return ret;
-}
-
static int inotify_release(struct inode *ignored, struct file *file)
{
struct fsnotify_group *group = file->private_data;
@@ -315,18 +206,6 @@ static long inotify_ioctl(struct file *file, unsigned int cmd,
return ret;
}
-static const struct file_operations inotify_fops = {
- .show_fdinfo = inotify_show_fdinfo,
- .poll = inotify_poll,
- .read = inotify_read,
- .fasync = fsnotify_fasync,
- .release = inotify_release,
- .unlocked_ioctl = inotify_ioctl,
- .compat_ioctl = inotify_ioctl,
- .llseek = noop_llseek,
-};
-
-
/*
* find_inode - resolve a user-given path to a specific inode
*/
@@ -488,8 +367,8 @@ out:
/*
* Send IN_IGNORED for this wd, remove this wd from the idr.
*/
-void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark,
- struct fsnotify_group *group)
+void inotify_ignored(struct fsnotify_mark *fsn_mark,
+ struct fsnotify_group *group)
{
struct inotify_inode_mark *i_mark;
@@ -498,8 +377,6 @@ void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark,
NULL, FSNOTIFY_EVENT_NONE, NULL, 0);
i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
- /* remove this mark from the idr */
- inotify_remove_from_idr(group, i_mark);
atomic_dec(&group->inotify_data.user->inotify_watches);
}
@@ -665,6 +542,136 @@ static struct fsnotify_group *inotify_new_group(unsigned int max_events)
return group;
}
+/*
+ * Copy an event to user space, returning how much we copied.
+ *
+ * We already checked that the event size is smaller than the
+ * buffer we had in "get_one_event()" above.
+ */
+static ssize_t copy_event_to_user(struct fsnotify_group *group,
+ struct fsnotify_event *fsn_event,
+ char __user *buf)
+{
+ struct inotify_event inotify_event;
+ struct inotify_event_info *event;
+ struct inotify_inode_mark *found_i_mark = NULL;
+ size_t event_size = sizeof(struct inotify_event);
+ size_t name_len;
+ size_t pad_name_len;
+
+ pr_debug("%s: group=%p event=%p\n", __func__, group, fsn_event);
+
+ event = INOTIFY_E(fsn_event);
+ name_len = event->name_len;
+ /*
+ * round up name length so it is a multiple of event_size
+ * plus an extra byte for the terminating '\0'.
+ */
+ pad_name_len = round_event_name_len(fsn_event);
+ inotify_event.len = pad_name_len;
+ inotify_event.mask = inotify_mask_to_arg(fsn_event->mask);
+ inotify_event.wd = event->wd;
+ inotify_event.cookie = event->sync_cookie;
+
+ /* send the main event */
+ if (copy_to_user(buf, &inotify_event, event_size))
+ return -EFAULT;
+
+ if (inotify_event.mask & IN_IGNORED) {
+ found_i_mark = inotify_idr_find(group, inotify_event.wd);
+ if (found_i_mark) {
+ /* remove this mark from the idr */
+ inotify_remove_from_idr(group, found_i_mark);
+ /* match ref taken by inotify_idr_find */
+ fsnotify_put_mark(&found_i_mark->fsn_mark);
+ }
+ }
+
+ buf += event_size;
+
+ /*
+ * fsnotify only stores the pathname, so here we have to send the pathname
+ * and then pad that pathname out to a multiple of sizeof(inotify_event)
+ * with zeros.
+ */
+ if (pad_name_len) {
+ /* copy the path name */
+ if (copy_to_user(buf, event->name, name_len))
+ return -EFAULT;
+ buf += name_len;
+
+ /* fill userspace with 0's */
+ if (clear_user(buf, pad_name_len - name_len))
+ return -EFAULT;
+ event_size += pad_name_len;
+ }
+
+ return event_size;
+}
+
+static ssize_t inotify_read(struct file *file, char __user *buf,
+ size_t count, loff_t *pos)
+{
+ struct fsnotify_group *group;
+ struct fsnotify_event *kevent;
+ char __user *start;
+ int ret;
+ DEFINE_WAIT(wait);
+
+ start = buf;
+ group = file->private_data;
+
+ while (1) {
+ prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE);
+
+ mutex_lock(&group->notification_mutex);
+ kevent = get_one_event(group, count);
+ mutex_unlock(&group->notification_mutex);
+
+ pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent);
+
+ if (kevent) {
+ ret = PTR_ERR(kevent);
+ if (IS_ERR(kevent))
+ break;
+ ret = copy_event_to_user(group, kevent, buf);
+ fsnotify_destroy_event(group, kevent);
+ if (ret < 0)
+ break;
+ buf += ret;
+ count -= ret;
+ continue;
+ }
+
+ ret = -EAGAIN;
+ if (file->f_flags & O_NONBLOCK)
+ break;
+ ret = -ERESTARTSYS;
+ if (signal_pending(current))
+ break;
+
+ if (start != buf)
+ break;
+
+ schedule();
+ }
+
+ finish_wait(&group->notification_waitq, &wait);
+ if (start != buf && ret != -EFAULT)
+ ret = buf - start;
+ return ret;
+}
+
+static const struct file_operations inotify_fops = {
+ .show_fdinfo = inotify_show_fdinfo,
+ .poll = inotify_poll,
+ .read = inotify_read,
+ .fasync = fsnotify_fasync,
+ .release = inotify_release,
+ .unlocked_ioctl = inotify_ioctl,
+ .compat_ioctl = inotify_ioctl,
+ .llseek = noop_llseek,
+};
/* inotify syscalls */
SYSCALL_DEFINE1(inotify_init1, int, flags)
--
2.0.0.rc2
--
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