KFunc bpf_ct_set_nat_info
Set source or destination network address translation address
Definition
Set source or destination address network translation 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, nf_nat_manip_type manip)
Usage
The bpf_ct_set_nat_info kfunc helper in order to set source and destination nat addresses/ports in a new allocated connection tracking entry not inserted in the connection tracking table yet.
Program types
The following program types can make use of this kfunc:
Example
// SPDX-License-Identifier: GPL-2.0
#include <vmlinux.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>
#define EAFNOSUPPORT 97
#define EPROTO 71
#define ENONET 64
#define EINVAL 22
#define ENOENT 2
extern unsigned long CONFIG_HZ __kconfig;
int test_einval_bpf_tuple = 0;
int test_einval_reserved = 0;
int test_einval_netns_id = 0;
int test_einval_len_opts = 0;
int test_eproto_l4proto = 0;
int test_enonet_netns_id = 0;
int test_enoent_lookup = 0;
int test_eafnosupport = 0;
int test_alloc_entry = -EINVAL;
int test_insert_entry = -EAFNOSUPPORT;
int test_succ_lookup = -ENOENT;
u32 test_delta_timeout = 0;
u32 test_status = 0;
u32 test_insert_lookup_mark = 0;
int test_snat_addr = -EINVAL;
int test_dnat_addr = -EINVAL;
__be32 saddr = 0;
__be16 sport = 0;
__be32 daddr = 0;
__be16 dport = 0;
int test_exist_lookup = -ENOENT;
u32 test_exist_lookup_mark = 0;
enum nf_nat_manip_type___local {
NF_NAT_MANIP_SRC___local,
NF_NAT_MANIP_DST___local
};
struct nf_conn;
struct bpf_ct_opts___local {
s32 netns_id;
s32 error;
u8 l4proto;
u8 reserved[3];
} __attribute__((preserve_access_index));
struct nf_conn *bpf_xdp_ct_alloc(struct xdp_md *, struct bpf_sock_tuple *, u32,
struct bpf_ct_opts___local *, u32) __ksym;
struct nf_conn *bpf_xdp_ct_lookup(struct xdp_md *, struct bpf_sock_tuple *, u32,
struct bpf_ct_opts___local *, u32) __ksym;
struct nf_conn *bpf_skb_ct_alloc(struct __sk_buff *, struct bpf_sock_tuple *, u32,
struct bpf_ct_opts___local *, u32) __ksym;
struct nf_conn *bpf_skb_ct_lookup(struct __sk_buff *, struct bpf_sock_tuple *, u32,
struct bpf_ct_opts___local *, u32) __ksym;
struct nf_conn *bpf_ct_insert_entry(struct nf_conn *) __ksym;
void bpf_ct_release(struct nf_conn *) __ksym;
void bpf_ct_set_timeout(struct nf_conn *, u32) __ksym;
int bpf_ct_change_timeout(struct nf_conn *, u32) __ksym;
int bpf_ct_set_status(struct nf_conn *, u32) __ksym;
int bpf_ct_change_status(struct nf_conn *, u32) __ksym;
int bpf_ct_set_nat_info(struct nf_conn *, union nf_inet_addr *,
int port, enum nf_nat_manip_type___local) __ksym;
static __always_inline void
nf_ct_test(struct nf_conn *(*lookup_fn)(void *, struct bpf_sock_tuple *, u32,
struct bpf_ct_opts___local *, u32),
struct nf_conn *(*alloc_fn)(void *, struct bpf_sock_tuple *, u32,
struct bpf_ct_opts___local *, u32),
void *ctx)
{
struct bpf_ct_opts___local opts_def = { .l4proto = IPPROTO_TCP, .netns_id = -1 };
struct bpf_sock_tuple bpf_tuple;
struct nf_conn *ct;
__builtin_memset(&bpf_tuple, 0, sizeof(bpf_tuple.ipv4));
ct = lookup_fn(ctx, NULL, 0, &opts_def, sizeof(opts_def));
if (ct)
bpf_ct_release(ct);
else
test_einval_bpf_tuple = opts_def.error;
opts_def.reserved[0] = 1;
ct = lookup_fn(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4), &opts_def,
sizeof(opts_def));
opts_def.reserved[0] = 0;
opts_def.l4proto = IPPROTO_TCP;
if (ct)
bpf_ct_release(ct);
else
test_einval_reserved = opts_def.error;
opts_def.netns_id = -2;
ct = lookup_fn(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4), &opts_def,
sizeof(opts_def));
opts_def.netns_id = -1;
if (ct)
bpf_ct_release(ct);
else
test_einval_netns_id = opts_def.error;
ct = lookup_fn(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4), &opts_def,
sizeof(opts_def) - 1);
if (ct)
bpf_ct_release(ct);
else
test_einval_len_opts = opts_def.error;
opts_def.l4proto = IPPROTO_ICMP;
ct = lookup_fn(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4), &opts_def,
sizeof(opts_def));
opts_def.l4proto = IPPROTO_TCP;
if (ct)
bpf_ct_release(ct);
else
test_eproto_l4proto = opts_def.error;
opts_def.netns_id = 0xf00f;
ct = lookup_fn(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4), &opts_def,
sizeof(opts_def));
opts_def.netns_id = -1;
if (ct)
bpf_ct_release(ct);
else
test_enonet_netns_id = opts_def.error;
ct = lookup_fn(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4), &opts_def,
sizeof(opts_def));
if (ct)
bpf_ct_release(ct);
else
test_enoent_lookup = opts_def.error;
ct = lookup_fn(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4) - 1, &opts_def,
sizeof(opts_def));
if (ct)
bpf_ct_release(ct);
else
test_eafnosupport = opts_def.error;
bpf_tuple.ipv4.saddr = bpf_get_prandom_u32(); /* src IP */
bpf_tuple.ipv4.daddr = bpf_get_prandom_u32(); /* dst IP */
bpf_tuple.ipv4.sport = bpf_get_prandom_u32(); /* src port */
bpf_tuple.ipv4.dport = bpf_get_prandom_u32(); /* dst port */
ct = alloc_fn(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4), &opts_def,
sizeof(opts_def));
if (ct) {
__u16 sport = bpf_get_prandom_u32();
__u16 dport = bpf_get_prandom_u32();
union nf_inet_addr saddr = {};
union nf_inet_addr daddr = {};
struct nf_conn *ct_ins;
bpf_ct_set_timeout(ct, 10000);
ct->mark = 77;
/* snat */
saddr.ip = bpf_get_prandom_u32();
bpf_ct_set_nat_info(ct, &saddr, sport, NF_NAT_MANIP_SRC___local);
/* dnat */
daddr.ip = bpf_get_prandom_u32();
bpf_ct_set_nat_info(ct, &daddr, dport, NF_NAT_MANIP_DST___local);
ct_ins = bpf_ct_insert_entry(ct);
if (ct_ins) {
struct nf_conn *ct_lk;
ct_lk = lookup_fn(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4),
&opts_def, sizeof(opts_def));
if (ct_lk) {
struct nf_conntrack_tuple *tuple;
/* check snat and dnat addresses */
tuple = &ct_lk->tuplehash[IP_CT_DIR_REPLY].tuple;
if (tuple->dst.u3.ip == saddr.ip &&
tuple->dst.u.all == bpf_htons(sport))
test_snat_addr = 0;
if (tuple->src.u3.ip == daddr.ip &&
tuple->src.u.all == bpf_htons(dport))
test_dnat_addr = 0;
/* update ct entry timeout */
bpf_ct_change_timeout(ct_lk, 10000);
test_delta_timeout = ct_lk->timeout - bpf_jiffies64();
test_delta_timeout /= CONFIG_HZ;
test_insert_lookup_mark = ct_lk->mark;
bpf_ct_change_status(ct_lk,
IPS_CONFIRMED | IPS_SEEN_REPLY);
test_status = ct_lk->status;
bpf_ct_release(ct_lk);
test_succ_lookup = 0;
}
bpf_ct_release(ct_ins);
test_insert_entry = 0;
}
test_alloc_entry = 0;
}
bpf_tuple.ipv4.saddr = saddr;
bpf_tuple.ipv4.daddr = daddr;
bpf_tuple.ipv4.sport = sport;
bpf_tuple.ipv4.dport = dport;
ct = lookup_fn(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4), &opts_def,
sizeof(opts_def));
if (ct) {
test_exist_lookup = 0;
if (ct->mark == 42) {
ct->mark++;
test_exist_lookup_mark = ct->mark;
}
bpf_ct_release(ct);
} else {
test_exist_lookup = opts_def.error;
}
}
SEC("xdp")
int nf_xdp_ct_test(struct xdp_md *ctx)
{
nf_ct_test((void *)bpf_xdp_ct_lookup, (void *)bpf_xdp_ct_alloc, ctx);
return 0;
}
SEC("tc")
int nf_skb_ct_test(struct __sk_buff *ctx)
{
nf_ct_test((void *)bpf_skb_ct_lookup, (void *)bpf_skb_ct_alloc, ctx);
return 0;
}
char _license[] SEC("license") = "GPL";