From e179e87a1179e272a9bdabb0220b17d61d099ee3 Mon Sep 17 00:00:00 2001 From: Phil Sutter Date: Thu, 6 Feb 2020 15:08:41 +0100 Subject: xtables-translate: Fix for interface name corner-cases There are two special situations xlate_ifname() didn't cover for: * Interface name containing '*': This went unchanged, creating a command nft wouldn't accept. Instead translate into '\*' which doesn't change semantics. * Interface name being '+': Can't translate into nft wildcard character as nft doesn't accept asterisk-only interface names. Instead decide what to do based on 'invert' value: Skip match creation if false, match against an invalid interface name if true. Also add a test to make sure future changes to this behaviour are noticed. Signed-off-by: Phil Sutter --- iptables/xtables-translate.c | 33 ++++++++++++++++++++++++++++----- 1 file changed, 28 insertions(+), 5 deletions(-) (limited to 'iptables/xtables-translate.c') diff --git a/iptables/xtables-translate.c b/iptables/xtables-translate.c index 77a186b9..c4e177c0 100644 --- a/iptables/xtables-translate.c +++ b/iptables/xtables-translate.c @@ -32,15 +32,38 @@ void xlate_ifname(struct xt_xlate *xl, const char *nftmeta, const char *ifname, bool invert) { - int ifaclen = strlen(ifname); - char iface[IFNAMSIZ]; + int ifaclen = strlen(ifname), i, j; + char iface[IFNAMSIZ * 2]; if (ifaclen < 1 || ifaclen >= IFNAMSIZ) return; - strcpy(iface, ifname); - if (iface[ifaclen - 1] == '+') - iface[ifaclen - 1] = '*'; + for (i = 0, j = 0; i < ifaclen + 1; i++, j++) { + switch (ifname[i]) { + case '+': + iface[j] = '*'; + break; + case '*': + iface[j++] = '\\'; + /* fall through */ + default: + iface[j] = ifname[i]; + break; + } + } + + if (ifaclen == 1 && ifname[0] == '+') { + /* Nftables does not support wildcard only string. Workaround + * is easy, given that this will match always or never + * depending on 'invert' value. To match always, simply don't + * generate an expression. To match never, use an invalid + * interface name (kernel doesn't accept '/' in names) to match + * against. */ + if (!invert) + return; + strcpy(iface, "INVAL/D"); + invert = false; + } xt_xlate_add(xl, "%s %s\"%s\" ", nftmeta, invert ? "!= " : "", iface); } -- cgit v1.2.3