netfilter: ctnetlink: fix creation of conntrack with helpers This patch fixes a bug that triggers an assertion if you create a conntrack entry with a helper and netfilter debugging is enabled. Basically, we hit the assertion because the confirmation flag is set before the conntrack extensions are added. To fix this, we move the extension addition before the aforementioned flag is set. This patch also removes the possibility of setting a helper for existing conntracks. This operation would also trigger the assertion since we are not allowed to add new extensions for existing conntracks. We know noone that could benefit from this operation sanely. Thanks to Eric Dumazet for initial posting a preliminary patch to address this issue. Reported-by: David Ramblewski Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_netlink.c | 22 +++++++++++----------- 1 files changed, 11 insertions(+), 11 deletions(-) diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index 8b05f36..2b2af63 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -1077,9 +1077,8 @@ ctnetlink_change_helper(struct nf_conn *ct, const struct nlattr * const cda[]) /* need to zero data of old helper */ memset(&help->help, 0, sizeof(help->help)); } else { - help = nf_ct_helper_ext_add(ct, GFP_ATOMIC); - if (help == NULL) - return -ENOMEM; + /* we cannot set a helper for an existing conntrack */ + return -EOPNOTSUPP; } rcu_assign_pointer(help->helper, helper); @@ -1263,7 +1262,6 @@ ctnetlink_create_conntrack(struct net *net, u16 zone, ct->timeout.expires = ntohl(nla_get_be32(cda[CTA_TIMEOUT])); ct->timeout.expires = jiffies + ct->timeout.expires * HZ; - ct->status |= IPS_CONFIRMED; rcu_read_lock(); if (cda[CTA_HELP]) { @@ -1314,14 +1312,19 @@ ctnetlink_create_conntrack(struct net *net, u16 zone, goto err2; } - if (cda[CTA_STATUS]) { - err = ctnetlink_change_status(ct, cda); + if (cda[CTA_NAT_SRC] || cda[CTA_NAT_DST]) { + err = ctnetlink_change_nat(ct, cda); if (err < 0) goto err2; } - if (cda[CTA_NAT_SRC] || cda[CTA_NAT_DST]) { - err = ctnetlink_change_nat(ct, cda); + nf_ct_acct_ext_add(ct, GFP_ATOMIC); + nf_ct_ecache_ext_add(ct, 0, 0, GFP_ATOMIC); + /* we must add conntrack extensions before confirmation. */ + ct->status |= IPS_CONFIRMED; + + if (cda[CTA_STATUS]) { + err = ctnetlink_change_status(ct, cda); if (err < 0) goto err2; } @@ -1340,9 +1343,6 @@ ctnetlink_create_conntrack(struct net *net, u16 zone, goto err2; } - nf_ct_acct_ext_add(ct, GFP_ATOMIC); - nf_ct_ecache_ext_add(ct, 0, 0, GFP_ATOMIC); - #if defined(CONFIG_NF_CONNTRACK_MARK) if (cda[CTA_MARK]) ct->mark = ntohl(nla_get_be32(cda[CTA_MARK]));