[PATCH bpf-next 3/4] net: netfilter: add bpf_ct_set_nat_info kfunc helper

Lorenzo Bianconi
2022-09-01T16:44:21Z

Introduce bpf_ct_set_nat_info kfunc helper in order to set source and
destination nat addresses/ports in a new allocated ct entry not inserted
in the connection tracking table yet.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
net/netfilter/nf_conntrack_bpf.c | 49 +++++++++++++++++++++++++++++++-
1 file changed, 48 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_conntrack_bpf.c b/net/netfilter/nf_conntrack_bpf.c
index 1cd87b28c9b0..85b8c7ee00af 100644
--- a/net/netfilter/nf_conntrack_bpf.c
+++ b/net/netfilter/nf_conntrack_bpf.c
@@ -14,6 +14,7 @@
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_bpf.h>
#include <net/netfilter/nf_conntrack_core.h>
+#include <net/netfilter/nf_nat.h>

/* bpf_ct_opts - Options for CT lookup helpers
*
@@ -134,7 +135,6 @@ __bpf_nf_ct_alloc_entry(struct net *net, struct bpf_sock_tuple *bpf_tuple,

memset(&ct->proto, 0, sizeof(ct->proto));
__nf_ct_set_timeout(ct, timeout * HZ);
- ct->status |= IPS_CONFIRMED;

out:
if (opts->netns_id >= 0)
@@ -339,6 +339,7 @@ struct nf_conn *bpf_ct_insert_entry(struct nf_conn___init *nfct_i)
struct nf_conn *nfct = (struct nf_conn *)nfct_i;
int err;

+ nfct->status |= IPS_CONFIRMED;
err = nf_conntrack_hash_check_insert(nfct);
if (err < 0) {
nf_conntrack_free(nfct);
@@ -424,6 +425,51 @@ int bpf_ct_change_status(struct nf_conn *nfct, u32 status)
return nf_ct_change_status_common(nfct, status);
}

+/* bpf_ct_set_nat_info - Set source or destination nat address
+ *
+ * Set source or destination nat address of the newly allocated
+ * nf_conn before insertion. This must be invoked for referenced
+ * PTR_TO_BTF_ID to nf_conn___init.
+ *
+ * Parameters:
+ * @nfct - Pointer to referenced nf_conn object, obtained using
+ * bpf_xdp_ct_alloc or bpf_skb_ct_alloc.
+ * @addr - Nat source/destination address
+ * @port - Nat source/destination port
+ * @manip - NF_NAT_MANIP_SRC or NF_NAT_MANIP_DST
+ */
+int bpf_ct_set_nat_info(struct nf_conn___init *nfct__ref,
+ union nf_inet_addr *addr, __be16 *port,
+ enum nf_nat_manip_type manip)
+{
+#if ((IS_MODULE(CONFIG_NF_NAT) && IS_MODULE(CONFIG_NF_CONNTRACK)) || \
+ IS_BUILTIN(CONFIG_NF_NAT))
+ struct nf_conn *ct = (struct nf_conn *)nfct__ref;
+ u16 proto = nf_ct_l3num(ct);
+ struct nf_nat_range2 range;
+
+ if (proto != NFPROTO_IPV4 && proto != NFPROTO_IPV6)
+ return -EINVAL;
+
+ if (!addr)
+ return -EINVAL;
+
+ memset(&range, 0, sizeof(struct nf_nat_range2));
+ range.flags = NF_NAT_RANGE_MAP_IPS;
+ range.min_addr = *addr;
+ range.max_addr = *addr;
+ if (port) {
+ range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
+ range.min_proto.all = *port;
+ range.max_proto.all = *port;
+ }
+
+ return nf_nat_setup_info(ct, &range, manip) == NF_DROP ? -ENOMEM : 0;
+#else
+ return -EOPNOTSUPP;
+#endif
+}
+
__diag_pop()

BTF_SET8_START(nf_ct_kfunc_set)
@@ -437,6 +483,7 @@ BTF_ID_FLAGS(func, bpf_ct_set_timeout, KF_TRUSTED_ARGS)
BTF_ID_FLAGS(func, bpf_ct_change_timeout, KF_TRUSTED_ARGS)
BTF_ID_FLAGS(func, bpf_ct_set_status, KF_TRUSTED_ARGS)
BTF_ID_FLAGS(func, bpf_ct_change_status, KF_TRUSTED_ARGS)
+BTF_ID_FLAGS(func, bpf_ct_set_nat_info)
BTF_SET8_END(nf_ct_kfunc_set)

static const struct btf_kfunc_id_set nf_conntrack_kfunc_set = {
--
2.37.2