netfilter: nf_tables: Allow set back-ends to report partial overlaps on insertion
Currently, the -EEXIST return code of ->insert() callbacks is ambiguous: it
might indicate that a given element (including intervals) already exists as
such, or that the new element would clash with existing ones.
If identical elements already exist, the front-end is ignoring this without
returning error, in case NLM_F_EXCL is not set. However, if the new element
can't be inserted due an overlap, we should report this to the user.
To this purpose, allow set back-ends to return -ENOTEMPTY on collision with
existing elements, translate that to -EEXIST, and return that to userspace,
no matter if NLM_F_EXCL was set.
Reported-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 38c680f..d11f1a7 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5082,6 +5082,11 @@
err = -EBUSY;
else if (!(nlmsg_flags & NLM_F_EXCL))
err = 0;
+ } else if (err == -ENOTEMPTY) {
+ /* ENOTEMPTY reports overlapping between this element
+ * and an existing one.
+ */
+ err = -EEXIST;
}
goto err_element_clash;
}
