// SPDX-License-Identifier: GPL-2.0-only
/* Unstable Conntrack 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_verifier.h>
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/filter.h>
#include <linux/mutex.h>
#include <linux/types.h>
#include <linux/btf_ids.h>
#include <linux/net_namespace.h>
#include <net/xdp.h>
#include <net/netfilter/nf_conntrack_bpf.h>
#include <net/netfilter/nf_conntrack_core.h>
/* bpf_ct_opts - Options for CT lookup helpers
*
* Members:
* @netns_id - Specify the network namespace for lookup
* Values:
* BPF_F_CURRENT_NETNS (-1)
* Use namespace associated with ctx (xdp_md, __sk_buff)
* [0, S32_MAX]
* Network Namespace ID
* @error - Out parameter, set for any errors encountered
* Values:
* -EINVAL - Passed NULL for bpf_tuple pointer
* -EINVAL - opts->reserved is not 0
* -EINVAL - netns_id is less than -1
* -EINVAL - opts__sz isn't NF_BPF_CT_OPTS_SZ (16) or 12
* -EINVAL - opts->ct_zone_id set when
opts__sz isn't NF_BPF_CT_OPTS_SZ (16)
* -EPROTO - l4proto isn't one of IPPROTO_TCP or IPPROTO_UDP
* -ENONET - No network namespace found for netns_id
* -ENOENT - Conntrack lookup could not find entry for tuple
* -EAFNOSUPPORT - tuple__sz isn't one of sizeof(tuple->ipv4)
* or sizeof(tuple->ipv6)
* @l4proto - Layer 4 protocol
* Values:
* IPPROTO_TCP, IPPROTO_UDP
* @dir: - connection tracking tuple direction.
* @ct_zone_id - connection tracking zone id.
* @ct_zone_dir - connection tracking zone direction.
* @reserved - Reserved member, will be reused for more options in future
* Values:
* 0
*/
struct bpf_ct_opts {
s32 netns_id;
s32 error;
u8 l4proto;
u8 dir;
u16 ct_zone_id;
u8 ct_zone_dir;
u8 reserved[3];
};
enum {
NF_BPF_CT_OPTS_SZ = 16,
};
static int bpf_nf_ct_tuple_parse(struct bpf_sock_tuple *bpf_tuple,
u32 tuple_len, u8 protonum, u8 dir,
struct nf_conntrack_tuple *tuple)
{
union nf_inet_addr *src = dir ? &tuple->dst.u3 : &tuple->src.u3;
union nf_inet_addr *dst = dir ? &tuple->src.u3 : &tuple->dst.u3;
union nf_conntrack_man_proto *sport = dir ? (void *)&tuple->dst.u
: &tuple->src.u;
union nf_conntrack_man_proto *dport = dir ? &tuple->src.u
: (void *)&tuple->dst.u;
if (unlikely(protonum != IPPROTO_TCP && protonum != IPPROTO_UDP))
return -EPROTO;
memset(tuple, 0, sizeof(*tuple));
switch (tuple_len) {
case sizeof(bpf_tuple->ipv4):
tuple->src.l3num = AF_INET;
src->ip = bpf_tuple->ipv4.saddr;
sport->tcp.port = bpf_tuple->ipv4.sport;
dst->ip = bpf_tuple->ipv4.daddr;
dport->tcp.port = bpf_tuple->ipv4.dport;
break;
case sizeof(bpf_tuple->ipv6):
tuple->src.l3num = AF_INET6;
memcpy(src->ip6, bpf_tuple->ipv6.saddr, sizeof(bpf_tuple->ipv6.saddr));
sport->tcp.port = bpf_tuple->ipv6.sport;
memcpy(dst->ip6, bpf_tuple->ipv6.daddr, sizeof(bpf_tuple->ipv6.daddr));
dport->tcp.port = bpf_tuple->ipv6.dport;
break;
default:
return -EAFNOSUPPORT;
}
tuple->dst.protonum = protonum;
tuple->dst.dir = dir;
return 0;
}
static struct nf_conn *
__bpf_nf_ct_alloc_entry(struct net *net, struct bpf_sock_tuple *bpf_tuple,
u32 tuple_len, struct bpf_ct_opts *opts, u32 opts_len,
u32 timeout)
{
struct nf_conntrack_tuple otuple, rtuple;
struct nf_conntrack_zone ct_zone;
struct nf_conn *ct;
int err;
if (!opts || !bpf_tuple)
return ERR_PTR(-EINVAL);
if (!(opts_len == NF_BPF_CT_OPTS_SZ || opts_len == 12))
return ERR_PTR(-EINVAL);
if (opts_len == NF_BPF_CT_OPTS_SZ) {
if (opts->reserved[0] || opts->reserved[1] || opts->reserved[2])
return ERR_PTR(-EINVAL);
} else {
if (opts->ct_zone_id)
return ERR_PTR(-EINVAL);
}
if (unlikely(opts->netns_id < BPF_F_CURRENT_NETNS))
return ERR_PTR(-EINVAL);
err = bpf_nf_ct_tuple_parse(bpf_tuple, tuple_len, opts->l4proto,
IP_CT_DIR_ORIGINAL, &otuple);
if (err < 0)
return ERR_PTR(err);
err = bpf_nf_ct_tuple_parse(bpf_tuple, tuple_len, opts->l4proto,
IP_CT_DIR_REPLY, &rtuple);
if (err < 0)
return ERR_PTR(err);
if (opts->netns_id >= 0) {
net = get_net_ns_by_id(net, opts->netns_id);
if (unlikely(!net))
return ERR_PTR(-ENONET);
}
if (opts_len == NF_BPF_CT_OPTS_SZ) {
if (opts->ct_zone_dir == 0)
opts->ct_zone_dir = NF_CT_DEFAULT_ZONE_DIR;
nf_ct_zone_init(&ct_zone,
opts->ct_zone_id, opts->ct_zone_dir, 0);
} else {
ct_zone = nf_ct_zone_dflt;
}
ct = nf_conntrack_alloc(net, &ct_zone, &otuple, &rtuple,
GFP_ATOMIC);
if (IS_ERR(ct))
goto out;
memset(&ct->proto, 0, sizeof(ct->proto));
__nf_ct_set_timeout(ct, timeout * HZ);
out:
if (opts->netns_id >= 0)
put_net(net);
return ct;
}
static struct nf_conn *__bpf_nf_ct_lookup(struct net *net,
struct bpf_sock_tuple *bpf_tuple,
u32 tuple_len, struct bpf_ct_opts *opts,
u32 opts_len)
{
struct nf_conntrack_tuple_hash *hash;
struct nf_conntrack_tuple tuple;
struct nf_conntrack_zone ct_zone;
struct nf_conn *ct;
int err;
if (!opts || !bpf_tuple)
return ERR_PTR(-EINVAL);
if (!(opts_len == NF_BPF_CT_OPTS_SZ || opts_len == 12))
return ERR_PTR(-EINVAL);
if (opts_len == NF_BPF_CT_OPTS_SZ) {
if (opts->reserved[0] || opts->reserved[1] || opts->reserved[2])
return ERR_PTR(-EINVAL);
} else {
if (opts->ct_zone_id)
return ERR_PTR(-EINVAL);
}
if (unlikely(opts->l4proto != IPPROTO_TCP && opts->l4proto != IPPROTO_UDP))
return ERR_PTR(-EPROTO);
if (unlikely(opts->netns_id < BPF_F_CURRENT_NETNS))
return ERR_PTR(-EINVAL);
err = bpf_nf_ct_tuple_parse(bpf_tuple, tuple_len, opts->l4proto,
IP_CT_DIR_ORIGINAL, &tuple);
if (err < 0)
return ERR_PTR(err);
if (opts->netns_id >= 0) {
net = get_net_ns_by_id(net, opts->netns_id);
if (unlikely(!net))
return ERR_PTR(-ENONET);
}
if (opts_len == NF_BPF_CT_OPTS_SZ) {
if (opts->ct_zone_dir == 0)
opts->ct_zone_dir = NF_CT_DEFAULT_ZONE_DIR;
nf_ct_zone_init(&ct_zone,
opts->ct_zone_id, opts->ct_zone_dir, 0);
} else {
ct_zone = nf_ct_zone_dflt;
}
hash = nf_conntrack_find_get(net, &ct_zone, &tuple);
if (opts->netns_id >= 0)
put_net(net);
if (!hash)
return ERR_PTR(-ENOENT);
ct = nf_ct_tuplehash_to_ctrack(hash);
opts->dir = NF_CT_DIRECTION(hash);
return ct;
}
BTF_ID_LIST(btf_nf_conn_ids)
BTF_ID(struct, nf_conn)
BTF_ID(struct, nf_conn___init)
/* Check writes into `struct nf_conn` */
static int _nf_conntrack_btf_struct_access(struct bpf_verifier_log *log,
const struct bpf_reg_state *reg,
int off, int size)
{
const struct btf_type *ncit, *nct, *t;
size_t end;
ncit = btf_type_by_id(reg->btf, btf_nf_conn_ids[1]);
nct = btf_type_by_id(reg->btf, btf_nf_conn_ids[0]);
t = btf_type_by_id(reg->btf, reg->btf_id);
if (t != nct && t != ncit) {
bpf_log(log, "only read is supported\n");
return -EACCES;
}
/* `struct nf_conn` and `struct nf_conn___init` have the same layout
* so we are safe to simply merge offset checks here
*/
switch (off) {
#if defined(CONFIG_NF_CONNTRACK_MARK)
case offsetof(struct nf_conn, mark):
end = offsetofend(struct nf_conn, mark);
break;
#endif
default:
bpf_log(log, "no write support to nf_conn at off %d\n", off);
return -EACCES;
}
if (off + size > end) {
bpf_log(log,
"write access at off %d with size %d beyond the member of nf_conn ended at %zu\n",
off, size, end);
return -EACCES;
}
return 0;
}
__bpf_kfunc_start_defs();
/* bpf_xdp_ct_alloc - Allocate a new CT entry
*
* Parameters:
* @xdp_ctx - Pointer to ctx (xdp_md) in XDP program
* Cannot be NULL
* @bpf_tuple - Pointer to memory representing the tuple to look up
* Cannot be NULL
* @tuple__sz - Length of the tuple structure
* Must be one of sizeof(bpf_tuple->ipv4) or
* sizeof(bpf_tuple->ipv6)
* @opts - Additional options for allocation (documented above)
* Cannot be NULL
* @opts__sz - Length of the bpf_ct_opts structure
* Must be NF_BPF_CT_OPTS_SZ (16) or 12
*/
__bpf_kfunc struct nf_conn___init *
bpf_xdp_ct_alloc(struct xdp_md *xdp_ctx, struct bpf_sock_tuple *bpf_tuple,
u32 tuple__sz, struct bpf_ct_opts *opts, u32 opts__sz)
{
struct xdp_buff *ctx = (struct xdp_buff *)xdp_ctx;
struct nf_conn *nfct;
nfct = __bpf_nf_ct_alloc_entry(dev_net(ctx->rxq->dev), bpf_tuple, tuple__sz,
opts, opts__sz, 10);
if (IS_ERR(nfct)) {
if (opts)
opts->error = PTR_ERR(nfct);
return NULL;
}
return (struct nf_conn___init *)nfct;
}
/* bpf_xdp_ct_lookup - Lookup CT entry for the given tuple, and acquire a
* reference to it
*
* Parameters:
* @xdp_ctx - Pointer to ctx (xdp_md) in XDP program
* Cannot be NULL
* @bpf_tuple - Pointer to memory representing the tuple to look up
* Cannot be NULL
* @tuple__sz - Length of the tuple structure
* Must be one of sizeof(bpf_tuple->ipv4) or
* sizeof(bpf_tuple->ipv6)
* @opts - Additional options for lookup (documented above)
* Cannot be NULL
* @opts__sz - Length of the bpf_ct_opts structure
* Must be NF_BPF_CT_OPTS_SZ (16) or 12
*/
__bpf_kfunc struct nf_conn *
bpf_xdp_ct_lookup(struct xdp_md *xdp_ctx, struct bpf_sock_tuple *bpf_tuple,
u32 tuple__sz, struct bpf_ct_opts *opts, u32 opts__sz)
{
struct xdp_buff *ctx = (struct xdp_buff *)xdp_ctx;
struct net *caller_net;
struct nf_conn *nfct;
caller_net = dev_net(ctx->rxq->dev);
nfct = __bpf_nf_ct_lookup(caller_net, bpf_tuple, tuple__sz, opts, opts__sz);
if (IS_ERR(nfct)) {
if (opts)
opts->error = PTR_ERR(nfct);
return NULL;
}
return nfct;
}
/* bpf_skb_ct_alloc - Allocate a new CT entry
*
* Parameters:
* @skb_ctx - Pointer to ctx (__sk_buff) in TC program
* Cannot be NULL
* @bpf_tuple - Pointer to memory representing the tuple to look up
* Cannot be NULL
* @tuple__sz - Length of the tuple structure
* Must be one of sizeof(bpf_tuple->ipv4) or
* sizeof(bpf_tuple->ipv6)
* @opts - Additional options for allocation (documented above)
* Cannot be NULL
* @opts__sz - Length of the bpf_ct_opts structure
* Must be NF_BPF_CT_OPTS_SZ (16) or 12
*/
__bpf_kfunc struct nf_conn___init *
bpf_skb_ct_alloc(struct __sk_buff *skb_ctx, struct bpf_sock_tuple *bpf_tuple,
u32 tuple__sz, struct bpf_ct_opts *opts, u32 opts__sz)
{
struct sk_buff *skb = (struct sk_buff *)skb_ctx;
struct nf_conn *nfct;
struct net *net;
net = skb->dev ? dev_net(skb->dev) : sock_net(skb->sk);
nfct = __bpf_nf_ct_alloc_entry(net, bpf_tuple, tuple__sz, opts, opts__sz, 10);
if (IS_ERR(nfct)) {
if (opts)
opts->error = PTR_ERR(nfct);
return NULL;
}
return (struct nf_conn___init *)nfct;
}
/* bpf_skb_ct_lookup - Lookup CT entry for the given tuple, and acquire a
* reference to it
*
* Parameters:
* @skb_ctx - Pointer to ctx (__sk_buff) in TC program
* Cannot be NULL
* @bpf_tuple - Pointer to memory representing the tuple to look up
* Cannot be NULL
* @tuple__sz - Length of the tuple structure
* Must be one of sizeof(bpf_tuple->ipv4) or
* sizeof(bpf_tuple->ipv6)
* @opts - Additional options for lookup (documented above)
* Cannot be NULL
* @opts__sz - Length of the bpf_ct_opts structure
* Must be NF_BPF_CT_OPTS_SZ (16) or 12
*/
__bpf_kfunc struct nf_conn *
bpf_skb_ct_lookup(struct __sk_buff *skb_ctx, struct bpf_sock_tuple *bpf_tuple,
u32 tuple__sz, struct bpf_ct_opts *opts, u32 opts__sz)
{
struct sk_buff *skb = (struct sk_buff *)skb_ctx;
struct net *caller_net;
struct nf_conn *nfct;
caller_net = skb->dev ? dev_net(skb->dev) : sock_net(skb->sk);
nfct = __bpf_nf_ct_lookup(caller_net, bpf_tuple, tuple__sz, opts, opts__sz);
if (IS_ERR(nfct)) {
if (opts)
opts->error = PTR_ERR(nfct);
return NULL;
}
return nfct;
}
/* bpf_ct_insert_entry - Add the provided entry into a CT map
*
* This must be invoked for referenced PTR_TO_BTF_ID.
*
* @nfct - Pointer to referenced nf_conn___init object, obtained
* using bpf_xdp_ct_alloc or bpf_skb_ct_alloc.
*/
__bpf_kfunc struct nf_conn *bpf_ct_insert_entry(struct nf_conn___init *nfct_i)
{
struct nf_conn *nfct = (struct nf_conn *)nfct_i;
int err;
if (!nf_ct_is_confirmed(nfct))
nfct->timeout += nfct_time_stamp;
nfct->status |= IPS_CONFIRMED;
err = nf_conntrack_hash_check_insert(nfct);
if (err < 0) {
nf_conntrack_free(nfct);
return NULL;
}
return nfct;
}
/* bpf_ct_release - Release acquired nf_conn object
*
* This must be invoked for referenced PTR_TO_BTF_ID, and the verifier rejects
* the program if any references remain in the program in all of the explored
* states.
*
* Parameters:
* @nf_conn - Pointer to referenced nf_conn object, obtained using
* bpf_xdp_ct_lookup or bpf_skb_ct_lookup.
*/
__bpf_kfunc void bpf_ct_release(struct nf_conn *nfct)
{
nf_ct_put(nfct);
}
/* bpf_ct_set_timeout - Set timeout of allocated nf_conn
*
* Sets the default timeout of newly allocated nf_conn before insertion.
* This helper must be invoked for refcounted pointer to nf_conn___init.
*
* Parameters:
* @nfct - Pointer to referenced nf_conn object, obtained using
* bpf_xdp_ct_alloc or bpf_skb_ct_alloc.
* @timeout - Timeout in msecs.
*/
__bpf_kfunc void bpf_ct_set_timeout(struct nf_conn___init *nfct, u32 timeout)
{
__nf_ct_set_timeout((struct nf_conn *)nfct, msecs_to_jiffies(timeout));
}
/* bpf_ct_change_timeout - Change timeout of inserted nf_conn
*
* Change timeout associated of the inserted or looked up nf_conn.
* This helper must be invoked for refcounted pointer to nf_conn.
*
* Parameters:
* @nfct - Pointer to referenced nf_conn object, obtained using
* bpf_ct_insert_entry, bpf_xdp_ct_lookup, or bpf_skb_ct_lookup.
* @timeout - New timeout in msecs.
*/
__bpf_kfunc int bpf_ct_change_timeout(struct nf_conn *nfct, u32 timeout)
{
return __nf_ct_change_timeout(nfct, msecs_to_jiffies(timeout));
}
/* bpf_ct_set_status - Set status field of allocated nf_conn
*
* Set the status field 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.
* @status - New status value.
*/
__bpf_kfunc int bpf_ct_set_status(const struct nf_conn___init *nfct, u32 status)
{
return nf_ct_change_status_common((struct nf_conn *)nfct, status);
}
/* bpf_ct_change_status - Change status of inserted nf_conn
*
* Change the status field of the provided connection tracking entry.
* This must be invoked for referenced PTR_TO_BTF_ID to nf_conn.
*
* Parameters:
* @nfct - Pointer to referenced nf_conn object, obtained using
* bpf_ct_insert_entry, bpf_xdp_ct_lookup or bpf_skb_ct_lookup.
* @status - New status value.
*/
__bpf_kfunc int bpf_ct_change_status(struct nf_conn *nfct, u32 status)
{
return nf_ct_change_status_common(nfct, status);
}
__bpf_kfunc_end_defs();
BTF_KFUNCS_START(nf_ct_kfunc_set)
BTF_ID_FLAGS(func, bpf_xdp_ct_alloc, KF_ACQUIRE | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_xdp_ct_lookup, KF_ACQUIRE | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_skb_ct_alloc, KF_ACQUIRE | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_skb_ct_lookup, KF_ACQUIRE | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_ct_insert_entry, KF_ACQUIRE | KF_RET_NULL | KF_RELEASE)
BTF_ID_FLAGS(func, bpf_ct_release, KF_RELEASE)
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_KFUNCS_END(nf_ct_kfunc_set)
static const struct btf_kfunc_id_set nf_conntrack_kfunc_set = {
.owner = THIS_MODULE,
.set = &nf_ct_kfunc_set,
};
int register_nf_conntrack_bpf(void)
{
int ret;
ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &nf_conntrack_kfunc_set);
ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &nf_conntrack_kfunc_set);
if (!ret) {
mutex_lock(&nf_conn_btf_access_lock);
nfct_btf_struct_access = _nf_conntrack_btf_struct_access;
mutex_unlock(&nf_conn_btf_access_lock);
}
return ret;
}
void cleanup_nf_conntrack_bpf(void)
{
mutex_lock(&nf_conn_btf_access_lock);
nfct_btf_struct_access = NULL;
mutex_unlock(&nf_conn_btf_access_lock);
}
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