net: netfilter: move bpf_ct_set_nat_info kfunc in nf_nat_bpf.c

Remove circular dependency between nf_nat module and nf_conntrack one
moving bpf_ct_set_nat_info kfunc in nf_nat_bpf.c

Fixes: 0fabd2a ("net: netfilter: add bpf_ct_set_nat_info kfunc helper")
Suggested-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Yauheni Kaliuta <ykaliuta@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/51a65513d2cda3eeb0754842e8025ab3966068d8.1664490511.git.lorenzo@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Author: LorenzoBianconi

include/net/netfilter/nf_conntrack_bpf.h

@@ -4,6 +4,11 @@
 #define _NF_CONNTRACK_BPF_H
 
 #include <linux/kconfig.h>
+#include <net/netfilter/nf_conntrack.h>
+
+struct nf_conn___init {
+	struct nf_conn ct;
+};
 
 #if (IS_BUILTIN(CONFIG_NF_CONNTRACK) && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) || \
     (IS_MODULE(CONFIG_NF_CONNTRACK) && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))
@@ -24,4 +29,18 @@ static inline void cleanup_nf_conntrack_bpf(void)
 
 #endif
 
+#if (IS_BUILTIN(CONFIG_NF_NAT) && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) || \
+    (IS_MODULE(CONFIG_NF_NAT) && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))
+
+extern int register_nf_nat_bpf(void);
+
+#else
+
+static inline int register_nf_nat_bpf(void)
+{
+	return 0;
+}
+
+#endif
+
 #endif /* _NF_CONNTRACK_BPF_H */

net/netfilter/Makefile

@@ -60,6 +60,12 @@ obj-$(CONFIG_NF_NAT) += nf_nat.o
 nf_nat-$(CONFIG_NF_NAT_REDIRECT) += nf_nat_redirect.o
 nf_nat-$(CONFIG_NF_NAT_MASQUERADE) += nf_nat_masquerade.o
 
+ifeq ($(CONFIG_NF_NAT),m)
+nf_nat-$(CONFIG_DEBUG_INFO_BTF_MODULES) += nf_nat_bpf.o
+else ifeq ($(CONFIG_NF_NAT),y)
+nf_nat-$(CONFIG_DEBUG_INFO_BTF) += nf_nat_bpf.o
+endif
+
 # NAT helpers
 obj-$(CONFIG_NF_NAT_AMANDA) += nf_nat_amanda.o
 obj-$(CONFIG_NF_NAT_FTP) += nf_nat_ftp.o

net/netfilter/nf_conntrack_bpf.c

@@ -14,10 +14,8 @@
 #include <linux/types.h>
 #include <linux/btf_ids.h>
 #include <linux/net_namespace.h>
-#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
  *
@@ -239,10 +237,6 @@ __diag_push();
 __diag_ignore_all("-Wmissing-prototypes",
 		  "Global functions as their definitions will be in nf_conntrack BTF");
 
-struct nf_conn___init {
-	struct nf_conn ct;
-};
-
 /* bpf_xdp_ct_alloc - Allocate a new CT entry
  *
  * Parameters:
@@ -476,49 +470,6 @@ 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. Non-positive values are
- *		  interpreted as select a random port.
- * @manip	- NF_NAT_MANIP_SRC or NF_NAT_MANIP_DST
- */
-int bpf_ct_set_nat_info(struct nf_conn___init *nfct,
-			union nf_inet_addr *addr, int 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;
-	u16 proto = nf_ct_l3num(ct);
-	struct nf_nat_range2 range;
-
-	if (proto != NFPROTO_IPV4 && proto != NFPROTO_IPV6)
-		return -EINVAL;
-
-	memset(&range, 0, sizeof(struct nf_nat_range2));
-	range.flags = NF_NAT_RANGE_MAP_IPS;
-	range.min_addr = *addr;
-	range.max_addr = range.min_addr;
-	if (port > 0) {
-		range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
-		range.min_proto.all = cpu_to_be16(port);
-		range.max_proto.all = range.min_proto.all;
-	}
-
-	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)
@@ -532,7 +483,6 @@ 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, KF_TRUSTED_ARGS)
 BTF_SET8_END(nf_ct_kfunc_set)
 
 static const struct btf_kfunc_id_set nf_conntrack_kfunc_set = {

net/netfilter/nf_nat_bpf.c

@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Unstable NAT Helpers for XDP and TC-BPF hook
+ *
+ * These are called from the XDP and SCHED_CLS BPF programs. Note that it is
+ * allowed to break compatibility for these functions since the interface they
+ * are exposed through to BPF programs is explicitly unstable.
+ */
+
+#include <linux/bpf.h>
+#include <linux/btf_ids.h>
+#include <net/netfilter/nf_conntrack_bpf.h>
+#include <net/netfilter/nf_conntrack_core.h>
+#include <net/netfilter/nf_nat.h>
+
+__diag_push();
+__diag_ignore_all("-Wmissing-prototypes",
+		  "Global functions as their definitions will be in nf_nat BTF");
+
+/* 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. Non-positive values are
+ *		  interpreted as select a random port.
+ * @manip	- NF_NAT_MANIP_SRC or NF_NAT_MANIP_DST
+ */
+int bpf_ct_set_nat_info(struct nf_conn___init *nfct,
+			union nf_inet_addr *addr, int port,
+			enum nf_nat_manip_type manip)
+{
+	struct nf_conn *ct = (struct nf_conn *)nfct;
+	u16 proto = nf_ct_l3num(ct);
+	struct nf_nat_range2 range;
+
+	if (proto != NFPROTO_IPV4 && proto != NFPROTO_IPV6)
+		return -EINVAL;
+
+	memset(&range, 0, sizeof(struct nf_nat_range2));
+	range.flags = NF_NAT_RANGE_MAP_IPS;
+	range.min_addr = *addr;
+	range.max_addr = range.min_addr;
+	if (port > 0) {
+		range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
+		range.min_proto.all = cpu_to_be16(port);
+		range.max_proto.all = range.min_proto.all;
+	}
+
+	return nf_nat_setup_info(ct, &range, manip) == NF_DROP ? -ENOMEM : 0;
+}
+
+__diag_pop()
+
+BTF_SET8_START(nf_nat_kfunc_set)
+BTF_ID_FLAGS(func, bpf_ct_set_nat_info, KF_TRUSTED_ARGS)
+BTF_SET8_END(nf_nat_kfunc_set)
+
+static const struct btf_kfunc_id_set nf_bpf_nat_kfunc_set = {
+	.owner = THIS_MODULE,
+	.set   = &nf_nat_kfunc_set,
+};
+
+int register_nf_nat_bpf(void)
+{
+	int ret;
+
+	ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP,
+					&nf_bpf_nat_kfunc_set);
+	if (ret)
+		return ret;
+
+	return register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS,
+					 &nf_bpf_nat_kfunc_set);
+}

net/netfilter/nf_nat_core.c

@@ -16,7 +16,7 @@
 #include <linux/siphash.h>
 #include <linux/rtnetlink.h>
 
-#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_bpf.h>
 #include <net/netfilter/nf_conntrack_core.h>
 #include <net/netfilter/nf_conntrack_helper.h>
 #include <net/netfilter/nf_conntrack_seqadj.h>
@@ -1152,7 +1152,7 @@ static int __init nf_nat_init(void)
 	WARN_ON(nf_nat_hook != NULL);
 	RCU_INIT_POINTER(nf_nat_hook, &nat_hook);
 
-	return 0;
+	return register_nf_nat_bpf();
 }
 
 static void __exit nf_nat_cleanup(void)