netfilter: ctnetlink: allow userspace to modify labels
Add the ability to set/clear labels assigned to a conntrack
via ctnetlink.
To allow userspace to only alter specific bits, Pablo suggested to add
a new CTA_LABELS_MASK attribute:
The new set of active labels is then determined via
active = (active & ~mask) ^ changeset
i.e., the mask selects those bits in the existing set that should be
changed.
This follows the same method already used by MARK and CONNMARK targets.
Omitting CTA_LABELS_MASK is the same as setting all bits in CTA_LABELS_MASK
to 1: The existing set is replaced by the one from userspace.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 5f53863..2334cc5 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -961,6 +961,7 @@
return 0;
}
+#define __CTA_LABELS_MAX_LENGTH ((XT_CONNLABEL_MAXBIT + 1) / BITS_PER_BYTE)
static const struct nla_policy ct_nla_policy[CTA_MAX+1] = {
[CTA_TUPLE_ORIG] = { .type = NLA_NESTED },
[CTA_TUPLE_REPLY] = { .type = NLA_NESTED },
@@ -977,6 +978,10 @@
[CTA_NAT_SEQ_ADJ_REPLY] = { .type = NLA_NESTED },
[CTA_ZONE] = { .type = NLA_U16 },
[CTA_MARK_MASK] = { .type = NLA_U32 },
+ [CTA_LABELS] = { .type = NLA_BINARY,
+ .len = __CTA_LABELS_MAX_LENGTH },
+ [CTA_LABELS_MASK] = { .type = NLA_BINARY,
+ .len = __CTA_LABELS_MAX_LENGTH },
};
static int
@@ -1505,6 +1510,31 @@
#endif
static int
+ctnetlink_attach_labels(struct nf_conn *ct, const struct nlattr * const cda[])
+{
+#ifdef CONFIG_NF_CONNTRACK_LABELS
+ size_t len = nla_len(cda[CTA_LABELS]);
+ const void *mask = cda[CTA_LABELS_MASK];
+
+ if (len & (sizeof(u32)-1)) /* must be multiple of u32 */
+ return -EINVAL;
+
+ if (mask) {
+ if (nla_len(cda[CTA_LABELS_MASK]) == 0 ||
+ nla_len(cda[CTA_LABELS_MASK]) != len)
+ return -EINVAL;
+ mask = nla_data(cda[CTA_LABELS_MASK]);
+ }
+
+ len /= sizeof(u32);
+
+ return nf_connlabels_replace(ct, nla_data(cda[CTA_LABELS]), mask, len);
+#else
+ return -EOPNOTSUPP;
+#endif
+}
+
+static int
ctnetlink_change_conntrack(struct nf_conn *ct,
const struct nlattr * const cda[])
{
@@ -1550,6 +1580,11 @@
return err;
}
#endif
+ if (cda[CTA_LABELS]) {
+ err = ctnetlink_attach_labels(ct, cda);
+ if (err < 0)
+ return err;
+ }
return 0;
}
@@ -1758,6 +1793,10 @@
else
events = IPCT_NEW;
+ if (cda[CTA_LABELS] &&
+ ctnetlink_attach_labels(ct, cda) == 0)
+ events |= (1 << IPCT_LABEL);
+
nf_conntrack_eventmask_report((1 << IPCT_REPLY) |
(1 << IPCT_ASSURED) |
(1 << IPCT_HELPER) |
@@ -2055,6 +2094,11 @@
if (err < 0)
return err;
}
+ if (cda[CTA_LABELS]) {
+ err = ctnetlink_attach_labels(ct, cda);
+ if (err < 0)
+ return err;
+ }
#if defined(CONFIG_NF_CONNTRACK_MARK)
if (cda[CTA_MARK])
ct->mark = ntohl(nla_get_be32(cda[CTA_MARK]));