fanotify: limit number of listeners per user
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>
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@@ -18,6 +18,7 @@
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#define FANOTIFY_DEFAULT_MAX_EVENTS 16384
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#define FANOTIFY_DEFAULT_MAX_MARKS 8192
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#define FANOTIFY_DEFAULT_MAX_LISTENERS 128
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extern const struct fsnotify_ops fanotify_fsnotify_ops;
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@@ -656,6 +657,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
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{
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struct fsnotify_group *group;
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int f_flags, fd;
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struct user_struct *user;
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pr_debug("%s: flags=%d event_f_flags=%d\n",
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__func__, flags, event_f_flags);
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@@ -666,6 +668,12 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
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if (flags & ~FAN_ALL_INIT_FLAGS)
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return -EINVAL;
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user = get_current_user();
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if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) {
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free_uid(user);
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return -EMFILE;
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}
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f_flags = O_RDWR | FMODE_NONOTIFY;
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if (flags & FAN_CLOEXEC)
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f_flags |= O_CLOEXEC;
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@@ -677,6 +685,9 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
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if (IS_ERR(group))
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return PTR_ERR(group);
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group->fanotify_data.user = user;
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atomic_inc(&user->fanotify_listeners);
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group->fanotify_data.f_flags = event_f_flags;
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#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
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mutex_init(&group->fanotify_data.access_mutex);
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