| Message ID | 20230721201425.16448-1-phil@nwl.cc |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [iptables,1/2] nft: Special casing for among match in compare_matches() | expand |
On Fri, Jul 21, 2023 at 10:14:24PM +0200, Phil Sutter wrote: > When other extensions may have "garbage" appended to their data which > should not be considered for match comparison, among match is the > opposite in that it extends its data beyond the value in 'size' field. > Add special casing to cover for this, avoiding false-positive rule > comparison. > > Fixes: 26753888720d8 ("nft: bridge: Rudimental among extension support") > Signed-off-by: Phil Sutter <phil@nwl.cc> Series applied.
diff --git a/iptables/nft-shared.c b/iptables/nft-shared.c index 12860fbf6d575..0cd082b5396d0 100644 --- a/iptables/nft-shared.c +++ b/iptables/nft-shared.c @@ -381,6 +381,7 @@ bool compare_matches(struct xtables_rule_match *mt1, for (mp1 = mt1, mp2 = mt2; mp1 && mp2; mp1 = mp1->next, mp2 = mp2->next) { struct xt_entry_match *m1 = mp1->match->m; struct xt_entry_match *m2 = mp2->match->m; + size_t cmplen = mp1->match->userspacesize; if (strcmp(m1->u.user.name, m2->u.user.name) != 0) { DEBUGP("mismatching match name\n"); @@ -392,8 +393,10 @@ bool compare_matches(struct xtables_rule_match *mt1, return false; } - if (memcmp(m1->data, m2->data, - mp1->match->userspacesize) != 0) { + if (!strcmp(m1->u.user.name, "among")) + cmplen = m1->u.match_size - sizeof(*m1); + + if (memcmp(m1->data, m2->data, cmplen) != 0) { DEBUGP("mismatch match data\n"); return false; }
When other extensions may have "garbage" appended to their data which should not be considered for match comparison, among match is the opposite in that it extends its data beyond the value in 'size' field. Add special casing to cover for this, avoiding false-positive rule comparison. Fixes: 26753888720d8 ("nft: bridge: Rudimental among extension support") Signed-off-by: Phil Sutter <phil@nwl.cc> --- iptables/nft-shared.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)