From e7099d8a5a34d2876908a9fab4952dabdcfc5909 Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Thu, 28 Oct 2010 17:21:57 -0400 Subject: [PATCH] fanotify: limit the number of marks in a single fanotify group There is currently no limit on the number of marks a given fanotify group can have. Since fanotify is gated on CAP_SYS_ADMIN this was not seen as a serious DoS threat. This patch implements a default of 8192, the same as inotify to work towards removing the CAP_SYS_ADMIN gating and eliminating the default DoS'able status. Signed-off-by: Eric Paris --- fs/notify/fanotify/fanotify_user.c | 9 +++++++++ include/linux/fsnotify_backend.h | 1 + 2 files changed, 10 insertions(+) diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 43d66d9..1d33d7d 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -17,6 +17,7 @@ #include #define FANOTIFY_DEFAULT_MAX_EVENTS 16384 +#define FANOTIFY_DEFAULT_MAX_MARKS 8192 extern const struct fsnotify_ops fanotify_fsnotify_ops; @@ -584,6 +585,9 @@ static int fanotify_add_vfsmount_mark(struct fsnotify_group *group, if (!fsn_mark) { int ret; + if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks) + return -ENOSPC; + fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); if (!fsn_mark) return -ENOMEM; @@ -626,6 +630,9 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group, if (!fsn_mark) { int ret; + if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks) + return -ENOSPC; + fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); if (!fsn_mark) return -ENOMEM; @@ -700,6 +707,8 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS; } + group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS; + fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags); if (fd < 0) goto out_put_group; diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h index b37f3a7..49ceed6 100644 --- a/include/linux/fsnotify_backend.h +++ b/include/linux/fsnotify_backend.h @@ -169,6 +169,7 @@ struct fsnotify_group { bool bypass_perm; /* protected by access_mutex */ #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */ int f_flags; + unsigned int max_marks; } fanotify_data; #endif /* CONFIG_FANOTIFY */ }; -- 2.7.4