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fanotify: limit number of listeners per user

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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@redhat.com>
This commit is contained in:
Eric Paris 2010-10-28 17:21:58 -04:00
parent ac7e22dcfa
commit 4afeff8505
4 changed files with 25 additions and 1 deletions
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11
fs/notify/fanotify/fanotify.c
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@ -200,10 +200,19 @@ static bool fanotify_should_send_event(struct fsnotify_group *group,
return false; 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 = { const struct fsnotify_ops fanotify_fsnotify_ops = {
.handle_event = fanotify_handle_event, .handle_event = fanotify_handle_event,
.should_send_event = fanotify_should_send_event, .should_send_event = fanotify_should_send_event,
.free_group_priv = NULL, .free_group_priv = fanotify_free_group_priv,
.free_event_priv = NULL, .free_event_priv = NULL,
.freeing_mark = NULL, .freeing_mark = NULL,
}; };

11
fs/notify/fanotify/fanotify_user.c
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@ -18,6 +18,7 @@
#define FANOTIFY_DEFAULT_MAX_EVENTS 16384 #define FANOTIFY_DEFAULT_MAX_EVENTS 16384
#define FANOTIFY_DEFAULT_MAX_MARKS 8192 #define FANOTIFY_DEFAULT_MAX_MARKS 8192
#define FANOTIFY_DEFAULT_MAX_LISTENERS 128
extern const struct fsnotify_ops fanotify_fsnotify_ops; 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; struct fsnotify_group *group;
int f_flags, fd; int f_flags, fd;
struct user_struct *user;
pr_debug("%s: flags=%d event_f_flags=%d\n", pr_debug("%s: flags=%d event_f_flags=%d\n",
__func__, flags, event_f_flags); __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) if (flags & ~FAN_ALL_INIT_FLAGS)
return -EINVAL; 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; f_flags = O_RDWR | FMODE_NONOTIFY;
if (flags & FAN_CLOEXEC) if (flags & FAN_CLOEXEC)
f_flags |= O_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)) if (IS_ERR(group))
return PTR_ERR(group); return PTR_ERR(group);
group->fanotify_data.user = user;
atomic_inc(&user->fanotify_listeners);
group->fanotify_data.f_flags = event_f_flags; group->fanotify_data.f_flags = event_f_flags;
#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
mutex_init(&group->fanotify_data.access_mutex); mutex_init(&group->fanotify_data.access_mutex);

1
include/linux/fsnotify_backend.h
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@ -170,6 +170,7 @@ struct fsnotify_group {
#endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */ #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
int f_flags; int f_flags;
unsigned int max_marks; unsigned int max_marks;
struct user_struct *user;
} fanotify_data; } fanotify_data;
#endif /* CONFIG_FANOTIFY */ #endif /* CONFIG_FANOTIFY */
}; };

3
include/linux/sched.h
View File

@ -672,6 +672,9 @@ struct user_struct {
atomic_t inotify_watches; /* How many inotify watches does this user have? */ 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? */ atomic_t inotify_devs; /* How many inotify devs does this user have opened? */
#endif #endif
#ifdef CONFIG_FANOTIFY
atomic_t fanotify_listeners;
#endif
#ifdef CONFIG_EPOLL #ifdef CONFIG_EPOLL
atomic_t epoll_watches; /* The number of file descriptors currently watched */ atomic_t epoll_watches; /* The number of file descriptors currently watched */
#endif #endif