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-rw-r--r--net/netfilter/nf_conntrack_bpf.c513
1 files changed, 513 insertions, 0 deletions
diff --git a/net/netfilter/nf_conntrack_bpf.c b/net/netfilter/nf_conntrack_bpf.c
new file mode 100644
index 000000000000..8639e7efd0e2
--- /dev/null
+++ b/net/netfilter/nf_conntrack_bpf.c
@@ -0,0 +1,513 @@
+// 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/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 (12)
+ * -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.
+ * @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;
+ u8 reserved[2];
+};
+
+enum {
+ NF_BPF_CT_OPTS_SZ = 12,
+};
+
+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_conn *ct;
+ int err;
+
+ if (!opts || !bpf_tuple || opts->reserved[0] || opts->reserved[1] ||
+ opts_len != NF_BPF_CT_OPTS_SZ)
+ 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);
+ }
+
+ ct = nf_conntrack_alloc(net, &nf_ct_zone_dflt, &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_conn *ct;
+ int err;
+
+ if (!opts || !bpf_tuple || opts->reserved[0] || opts->reserved[1] ||
+ opts_len != NF_BPF_CT_OPTS_SZ)
+ 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);
+ }
+
+ hash = nf_conntrack_find_get(net, &nf_ct_zone_dflt, &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 btf *btf,
+ const struct btf_type *t, int off,
+ int size, enum bpf_access_type atype,
+ u32 *next_btf_id,
+ enum bpf_type_flag *flag)
+{
+ const struct btf_type *ncit;
+ const struct btf_type *nct;
+ size_t end;
+
+ ncit = btf_type_by_id(btf, btf_nf_conn_ids[1]);
+ nct = btf_type_by_id(btf, btf_nf_conn_ids[0]);
+
+ 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;
+}
+
+__diag_push();
+__diag_ignore_all("-Wmissing-prototypes",
+ "Global functions as their definitions will be in nf_conntrack BTF");
+
+/* 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 (12)
+ */
+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 (12)
+ */
+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 (12)
+ */
+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 (12)
+ */
+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.
+ */
+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);
+ 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.
+ */
+void bpf_ct_release(struct nf_conn *nfct)
+{
+ if (!nfct)
+ return;
+ 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.
+ */
+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.
+ */
+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.
+ */
+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.
+ */
+int bpf_ct_change_status(struct nf_conn *nfct, u32 status)
+{
+ return nf_ct_change_status_common(nfct, status);
+}
+
+__diag_pop()
+
+BTF_SET8_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_SET8_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);
+}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.