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[nf,1/4] nf_tables: Allow set back-ends to report partial overlaps on insertion

Message ID 1625b855afe7a5f5c9029fcf91f549fd3d8b4b3e.1583438771.git.sbrivio@redhat.com
State Changes Requested
Delegated to: Pablo Neira
Headers show
Series nftables: Consistently report partial and entire set overlaps | expand

Commit Message

Stefano Brivio March 5, 2020, 8:33 p.m. UTC 
From: Pablo Neira Ayuso <pablo@netfilter.org>

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>
---
Pablo, I added your From: here as the original patch came from you,
but I'm not sure how to handle this. Please change it as you see fit.

 net/netfilter/nf_tables_api.c | 5 +++++
 1 file changed, 5 insertions(+)
diff mbox series

Patch

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index d1318bdf49ca..51371efe8bf0 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5077,6 +5077,11 @@  static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
 				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;
 	}