From: Stefano Brivio sbrivio@redhat.com
commit 33d077996a87175b155fe88030e8fec7ca76327e upstream.
While checking the validity of insertion in __nft_rbtree_insert(), we currently ignore conflicting elements and intervals only if they are not active within the next generation.
However, if we consider expired elements and intervals as potentially conflicting and overlapping, we'll return error for entries that should be added instead. This is particularly visible with garbage collection intervals that are comparable with the element timeout itself, as reported by Mike Dillinger.
Other than the simple issue of denying insertion of valid entries, this might also result in insertion of a single element (opening or closing) out of a given interval. With single entries (that are inserted as intervals of size 1), this leads in turn to the creation of new intervals. For example:
# nft add element t s { 192.0.2.1 } # nft list ruleset [...] elements = { 192.0.2.1-255.255.255.255 }
Always ignore expired elements active in the next generation, while checking for conflicts.
It might be more convenient to introduce a new macro that covers both inactive and expired items, as this type of check also appears quite frequently in other set back-ends. This is however beyond the scope of this fix and can be deferred to a separate patch.
Other than the overlap detection cases introduced by commit 7c84d41416d8 ("netfilter: nft_set_rbtree: Detect partial overlaps on insertion"), we also have to cover the original conflict check dealing with conflicts between two intervals of size 1, which was introduced before support for timeout was introduced. This won't return an error to the user as -EEXIST is masked by nft if NLM_F_EXCL is not given, but would result in a silent failure adding the entry.
Reported-by: Mike Dillinger miked@softtalker.com Cc: stable@vger.kernel.org # 5.6.x Fixes: 8d8540c4f5e0 ("netfilter: nft_set_rbtree: add timeout support") Fixes: 7c84d41416d8 ("netfilter: nft_set_rbtree: Detect partial overlaps on insertion") Signed-off-by: Stefano Brivio sbrivio@redhat.com Acked-by: Phil Sutter phil@nwl.cc Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/netfilter/nft_set_rbtree.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-)
--- a/net/netfilter/nft_set_rbtree.c +++ b/net/netfilter/nft_set_rbtree.c @@ -271,12 +271,14 @@ static int __nft_rbtree_insert(const str
if (nft_rbtree_interval_start(new)) { if (nft_rbtree_interval_end(rbe) && - nft_set_elem_active(&rbe->ext, genmask)) + nft_set_elem_active(&rbe->ext, genmask) && + !nft_set_elem_expired(&rbe->ext)) overlap = false; } else { overlap = nft_rbtree_interval_end(rbe) && nft_set_elem_active(&rbe->ext, - genmask); + genmask) && + !nft_set_elem_expired(&rbe->ext); } } else if (d > 0) { p = &parent->rb_right; @@ -284,9 +286,11 @@ static int __nft_rbtree_insert(const str if (nft_rbtree_interval_end(new)) { overlap = nft_rbtree_interval_end(rbe) && nft_set_elem_active(&rbe->ext, - genmask); + genmask) && + !nft_set_elem_expired(&rbe->ext); } else if (nft_rbtree_interval_end(rbe) && - nft_set_elem_active(&rbe->ext, genmask)) { + nft_set_elem_active(&rbe->ext, genmask) && + !nft_set_elem_expired(&rbe->ext)) { overlap = true; } } else { @@ -294,15 +298,18 @@ static int __nft_rbtree_insert(const str nft_rbtree_interval_start(new)) { p = &parent->rb_left;
- if (nft_set_elem_active(&rbe->ext, genmask)) + if (nft_set_elem_active(&rbe->ext, genmask) && + !nft_set_elem_expired(&rbe->ext)) overlap = false; } else if (nft_rbtree_interval_start(rbe) && nft_rbtree_interval_end(new)) { p = &parent->rb_right;
- if (nft_set_elem_active(&rbe->ext, genmask)) + if (nft_set_elem_active(&rbe->ext, genmask) && + !nft_set_elem_expired(&rbe->ext)) overlap = false; - } else if (nft_set_elem_active(&rbe->ext, genmask)) { + } else if (nft_set_elem_active(&rbe->ext, genmask) && + !nft_set_elem_expired(&rbe->ext)) { *ext = &rbe->ext; return -EEXIST; } else {