From a963d710f367f68cd13d562a07db55ccb8daade9 Mon Sep 17 00:00:00 2001 From: Kevin Cernekee Date: Thu, 26 Jan 2017 14:49:43 -0800 Subject: [PATCH] netfilter: ctnetlink: Fix regression in CTA_STATUS processing The libnetfilter_conntrack userland library always sets IPS_CONFIRMED when building a CTA_STATUS attribute. If this toggles the bit from 0->1, the parser will return an error. On Linux 4.4+ this will cause any NFQA_EXP attribute in the packet to be ignored. This breaks conntrackd's userland helpers because they operate on unconfirmed connections. Instead of returning -EBUSY if the user program asks to modify an unchangeable bit, simply ignore the change. Also, fix the logic so that user programs are allowed to clear the bits that they are allowed to change. Signed-off-by: Kevin Cernekee Signed-off-by: Pablo Neira Ayuso --- .../linux/netfilter/nf_conntrack_common.h | 4 +++ net/netfilter/nf_conntrack_netlink.c | 26 ++++++++++++++++++- 2 files changed, 29 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/netfilter/nf_conntrack_common.h b/include/uapi/linux/netfilter/nf_conntrack_common.h index 6d074d14ee27..6a8e33dd4ecb 100644 --- a/include/uapi/linux/netfilter/nf_conntrack_common.h +++ b/include/uapi/linux/netfilter/nf_conntrack_common.h @@ -82,6 +82,10 @@ enum ip_conntrack_status { IPS_DYING_BIT = 9, IPS_DYING = (1 << IPS_DYING_BIT), + /* Bits that cannot be altered from userland. */ + IPS_UNCHANGEABLE_MASK = (IPS_NAT_DONE_MASK | IPS_NAT_MASK | + IPS_EXPECTED | IPS_CONFIRMED | IPS_DYING), + /* Connection has fixed timeout. */ IPS_FIXED_TIMEOUT_BIT = 10, IPS_FIXED_TIMEOUT = (1 << IPS_FIXED_TIMEOUT_BIT), diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index 27540455dc62..bf04b7e9d6f7 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -2269,6 +2269,30 @@ nla_put_failure: return -ENOSPC; } +static int +ctnetlink_update_status(struct nf_conn *ct, const struct nlattr * const cda[]) +{ + unsigned int status = ntohl(nla_get_be32(cda[CTA_STATUS])); + unsigned long d = ct->status ^ status; + + if (d & IPS_SEEN_REPLY && !(status & IPS_SEEN_REPLY)) + /* SEEN_REPLY bit can only be set */ + return -EBUSY; + + if (d & IPS_ASSURED && !(status & IPS_ASSURED)) + /* ASSURED bit can only be set */ + return -EBUSY; + + /* This check is less strict than ctnetlink_change_status() + * because callers often flip IPS_EXPECTED bits when sending + * an NFQA_CT attribute to the kernel. So ignore the + * unchangeable bits but do not error out. + */ + ct->status = (status & ~IPS_UNCHANGEABLE_MASK) | + (ct->status & IPS_UNCHANGEABLE_MASK); + return 0; +} + static int ctnetlink_glue_parse_ct(const struct nlattr *cda[], struct nf_conn *ct) { @@ -2280,7 +2304,7 @@ ctnetlink_glue_parse_ct(const struct nlattr *cda[], struct nf_conn *ct) return err; } if (cda[CTA_STATUS]) { - err = ctnetlink_change_status(ct, cda); + err = ctnetlink_update_status(ct, cda); if (err < 0) return err; } -- 2.30.2