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 <eparis@redhat.com>
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 <asm/ioctls.h>
#define FANOTIFY_DEFAULT_MAX_EVENTS 16384
+#define FANOTIFY_DEFAULT_MAX_MARKS 8192
extern const struct fsnotify_ops fanotify_fsnotify_ops;
@@ -584,6 +585,9 @@
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 @@
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 @@
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;