fanotify currently has no limit on the number of listeners a given user can
have open. This patch limits the total number of listeners per user to
128. This is the same as the inotify default limit.
Signed-off-by: Eric Paris <eparis@xxxxxxxxxx>
---
fs/notify/fanotify/fanotify.c | 11 ++++++++++-
fs/notify/fanotify/fanotify_user.c | 11 +++++++++++
include/linux/fsnotify_backend.h | 1 +
include/linux/sched.h | 3 +++
4 files changed, 25 insertions(+), 1 deletions(-)
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 85366c7..60c11c3 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -200,10 +200,19 @@ static bool fanotify_should_send_event(struct fsnotify_group *group,
return false;
}
+static void fanotify_free_group_priv(struct fsnotify_group *group)
+{
+ struct user_struct *user;
+
+ user = group->fanotify_data.user;
+ atomic_dec(&user->fanotify_listeners);
+ free_uid(user);
+}
+
const struct fsnotify_ops fanotify_fsnotify_ops = {
.handle_event = fanotify_handle_event,
.should_send_event = fanotify_should_send_event,
- .free_group_priv = NULL,
+ .free_group_priv = fanotify_free_group_priv,
.free_event_priv = NULL,
.freeing_mark = NULL,
};
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index f921610..a7d9369 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -18,6 +18,7 @@
#define FANOTIFY_DEFAULT_MAX_EVENTS 16384
#define FANOTIFY_DEFAULT_MAX_MARKS 8192
+#define FANOTIFY_DEFAULT_MAX_LISTENERS 128
extern const struct fsnotify_ops fanotify_fsnotify_ops;
@@ -656,6 +657,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
{
struct fsnotify_group *group;
int f_flags, fd;
+ struct user_struct *user;
pr_debug("%s: flags=%d event_f_flags=%d\n",
__func__, flags, event_f_flags);
@@ -666,6 +668,12 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
if (flags & ~FAN_ALL_INIT_FLAGS)
return -EINVAL;
+ user = get_current_user();
+ if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) {
+ free_uid(user);
+ return -EMFILE;
+ }
+
f_flags = O_RDWR | FMODE_NONOTIFY;
if (flags & FAN_CLOEXEC)
f_flags |= O_CLOEXEC;
@@ -677,6 +685,9 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
if (IS_ERR(group))
return PTR_ERR(group);
+ group->fanotify_data.user = user;
+ atomic_inc(&user->fanotify_listeners);
+
group->fanotify_data.f_flags = event_f_flags;
#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
mutex_init(&group->fanotify_data.access_mutex);
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 49ceed6..4366f45 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -170,6 +170,7 @@ struct fsnotify_group {
#endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
int f_flags;
unsigned int max_marks;
+ struct user_struct *user;
} fanotify_data;
#endif /* CONFIG_FANOTIFY */
};
diff --git a/include/linux/sched.h b/include/linux/sched.h
index be7adb7..6f420ba 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -672,6 +672,9 @@ struct user_struct {
atomic_t inotify_watches; /* How many inotify watches does this user have? */
atomic_t inotify_devs; /* How many inotify devs does this user have opened? */
#endif
+#ifdef CONFIG_FANOTIFY
+ atomic_t fanotify_listeners;
+#endif
#ifdef CONFIG_EPOLL
atomic_t epoll_watches; /* The number of file descriptors currently watched */
#endif
--
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