267 lines
7.7 KiB
C
267 lines
7.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Unstable Conntrack Helpers for XDP and TC-BPF hook
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*
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* These are called from the XDP and SCHED_CLS BPF programs. Note that it is
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* allowed to break compatibility for these functions since the interface they
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* are exposed through to BPF programs is explicitly unstable.
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*/
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#include <linux/bpf.h>
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#include <linux/btf.h>
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#include <linux/types.h>
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#include <linux/btf_ids.h>
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#include <linux/net_namespace.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_bpf.h>
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#include <net/netfilter/nf_conntrack_core.h>
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/* bpf_ct_opts - Options for CT lookup helpers
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*
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* Members:
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* @netns_id - Specify the network namespace for lookup
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* Values:
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* BPF_F_CURRENT_NETNS (-1)
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* Use namespace associated with ctx (xdp_md, __sk_buff)
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* [0, S32_MAX]
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* Network Namespace ID
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* @error - Out parameter, set for any errors encountered
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* Values:
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* -EINVAL - Passed NULL for bpf_tuple pointer
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* -EINVAL - opts->reserved is not 0
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* -EINVAL - netns_id is less than -1
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* -EINVAL - opts__sz isn't NF_BPF_CT_OPTS_SZ (12)
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* -EPROTO - l4proto isn't one of IPPROTO_TCP or IPPROTO_UDP
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* -ENONET - No network namespace found for netns_id
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* -ENOENT - Conntrack lookup could not find entry for tuple
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* -EAFNOSUPPORT - tuple__sz isn't one of sizeof(tuple->ipv4)
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* or sizeof(tuple->ipv6)
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* @l4proto - Layer 4 protocol
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* Values:
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* IPPROTO_TCP, IPPROTO_UDP
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* @dir: - connection tracking tuple direction.
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* @reserved - Reserved member, will be reused for more options in future
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* Values:
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* 0
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*/
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struct bpf_ct_opts {
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s32 netns_id;
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s32 error;
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u8 l4proto;
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u8 dir;
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u8 reserved[2];
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};
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enum {
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NF_BPF_CT_OPTS_SZ = 12,
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};
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static struct nf_conn *__bpf_nf_ct_lookup(struct net *net,
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struct bpf_sock_tuple *bpf_tuple,
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u32 tuple_len, u8 protonum,
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s32 netns_id, u8 *dir)
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{
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struct nf_conntrack_tuple_hash *hash;
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struct nf_conntrack_tuple tuple;
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struct nf_conn *ct;
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if (unlikely(protonum != IPPROTO_TCP && protonum != IPPROTO_UDP))
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return ERR_PTR(-EPROTO);
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if (unlikely(netns_id < BPF_F_CURRENT_NETNS))
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return ERR_PTR(-EINVAL);
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memset(&tuple, 0, sizeof(tuple));
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switch (tuple_len) {
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case sizeof(bpf_tuple->ipv4):
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tuple.src.l3num = AF_INET;
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tuple.src.u3.ip = bpf_tuple->ipv4.saddr;
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tuple.src.u.tcp.port = bpf_tuple->ipv4.sport;
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tuple.dst.u3.ip = bpf_tuple->ipv4.daddr;
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tuple.dst.u.tcp.port = bpf_tuple->ipv4.dport;
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break;
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case sizeof(bpf_tuple->ipv6):
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tuple.src.l3num = AF_INET6;
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memcpy(tuple.src.u3.ip6, bpf_tuple->ipv6.saddr, sizeof(bpf_tuple->ipv6.saddr));
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tuple.src.u.tcp.port = bpf_tuple->ipv6.sport;
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memcpy(tuple.dst.u3.ip6, bpf_tuple->ipv6.daddr, sizeof(bpf_tuple->ipv6.daddr));
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tuple.dst.u.tcp.port = bpf_tuple->ipv6.dport;
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break;
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default:
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return ERR_PTR(-EAFNOSUPPORT);
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}
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tuple.dst.protonum = protonum;
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if (netns_id >= 0) {
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net = get_net_ns_by_id(net, netns_id);
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if (unlikely(!net))
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return ERR_PTR(-ENONET);
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}
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hash = nf_conntrack_find_get(net, &nf_ct_zone_dflt, &tuple);
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if (netns_id >= 0)
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put_net(net);
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if (!hash)
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return ERR_PTR(-ENOENT);
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ct = nf_ct_tuplehash_to_ctrack(hash);
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if (dir)
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*dir = NF_CT_DIRECTION(hash);
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return ct;
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}
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__diag_push();
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__diag_ignore_all("-Wmissing-prototypes",
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"Global functions as their definitions will be in nf_conntrack BTF");
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/* bpf_xdp_ct_lookup - Lookup CT entry for the given tuple, and acquire a
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* reference to it
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*
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* Parameters:
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* @xdp_ctx - Pointer to ctx (xdp_md) in XDP program
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* Cannot be NULL
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* @bpf_tuple - Pointer to memory representing the tuple to look up
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* Cannot be NULL
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* @tuple__sz - Length of the tuple structure
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* Must be one of sizeof(bpf_tuple->ipv4) or
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* sizeof(bpf_tuple->ipv6)
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* @opts - Additional options for lookup (documented above)
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* Cannot be NULL
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* @opts__sz - Length of the bpf_ct_opts structure
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* Must be NF_BPF_CT_OPTS_SZ (12)
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*/
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struct nf_conn *
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bpf_xdp_ct_lookup(struct xdp_md *xdp_ctx, struct bpf_sock_tuple *bpf_tuple,
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u32 tuple__sz, struct bpf_ct_opts *opts, u32 opts__sz)
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{
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struct xdp_buff *ctx = (struct xdp_buff *)xdp_ctx;
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struct net *caller_net;
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struct nf_conn *nfct;
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BUILD_BUG_ON(sizeof(struct bpf_ct_opts) != NF_BPF_CT_OPTS_SZ);
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if (!opts)
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return NULL;
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if (!bpf_tuple || opts->reserved[0] || opts->reserved[1] ||
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opts__sz != NF_BPF_CT_OPTS_SZ) {
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opts->error = -EINVAL;
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return NULL;
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}
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caller_net = dev_net(ctx->rxq->dev);
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nfct = __bpf_nf_ct_lookup(caller_net, bpf_tuple, tuple__sz, opts->l4proto,
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opts->netns_id, &opts->dir);
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if (IS_ERR(nfct)) {
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opts->error = PTR_ERR(nfct);
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return NULL;
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}
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return nfct;
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}
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/* bpf_skb_ct_lookup - Lookup CT entry for the given tuple, and acquire a
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* reference to it
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*
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* Parameters:
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* @skb_ctx - Pointer to ctx (__sk_buff) in TC program
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* Cannot be NULL
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* @bpf_tuple - Pointer to memory representing the tuple to look up
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* Cannot be NULL
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* @tuple__sz - Length of the tuple structure
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* Must be one of sizeof(bpf_tuple->ipv4) or
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* sizeof(bpf_tuple->ipv6)
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* @opts - Additional options for lookup (documented above)
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* Cannot be NULL
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* @opts__sz - Length of the bpf_ct_opts structure
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* Must be NF_BPF_CT_OPTS_SZ (12)
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*/
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struct nf_conn *
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bpf_skb_ct_lookup(struct __sk_buff *skb_ctx, struct bpf_sock_tuple *bpf_tuple,
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u32 tuple__sz, struct bpf_ct_opts *opts, u32 opts__sz)
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{
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struct sk_buff *skb = (struct sk_buff *)skb_ctx;
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struct net *caller_net;
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struct nf_conn *nfct;
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BUILD_BUG_ON(sizeof(struct bpf_ct_opts) != NF_BPF_CT_OPTS_SZ);
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if (!opts)
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return NULL;
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if (!bpf_tuple || opts->reserved[0] || opts->reserved[1] ||
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opts__sz != NF_BPF_CT_OPTS_SZ) {
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opts->error = -EINVAL;
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return NULL;
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}
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caller_net = skb->dev ? dev_net(skb->dev) : sock_net(skb->sk);
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nfct = __bpf_nf_ct_lookup(caller_net, bpf_tuple, tuple__sz, opts->l4proto,
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opts->netns_id, &opts->dir);
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if (IS_ERR(nfct)) {
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opts->error = PTR_ERR(nfct);
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return NULL;
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}
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return nfct;
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}
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/* bpf_ct_release - Release acquired nf_conn object
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*
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* This must be invoked for referenced PTR_TO_BTF_ID, and the verifier rejects
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* the program if any references remain in the program in all of the explored
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* states.
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*
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* Parameters:
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* @nf_conn - Pointer to referenced nf_conn object, obtained using
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* bpf_xdp_ct_lookup or bpf_skb_ct_lookup.
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*/
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void bpf_ct_release(struct nf_conn *nfct)
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{
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if (!nfct)
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return;
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nf_ct_put(nfct);
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}
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__diag_pop()
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BTF_SET_START(nf_ct_xdp_check_kfunc_ids)
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BTF_ID(func, bpf_xdp_ct_lookup)
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BTF_ID(func, bpf_ct_release)
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BTF_SET_END(nf_ct_xdp_check_kfunc_ids)
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BTF_SET_START(nf_ct_tc_check_kfunc_ids)
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BTF_ID(func, bpf_skb_ct_lookup)
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BTF_ID(func, bpf_ct_release)
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BTF_SET_END(nf_ct_tc_check_kfunc_ids)
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BTF_SET_START(nf_ct_acquire_kfunc_ids)
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BTF_ID(func, bpf_xdp_ct_lookup)
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BTF_ID(func, bpf_skb_ct_lookup)
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BTF_SET_END(nf_ct_acquire_kfunc_ids)
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BTF_SET_START(nf_ct_release_kfunc_ids)
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BTF_ID(func, bpf_ct_release)
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BTF_SET_END(nf_ct_release_kfunc_ids)
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/* Both sets are identical */
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#define nf_ct_ret_null_kfunc_ids nf_ct_acquire_kfunc_ids
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static const struct btf_kfunc_id_set nf_conntrack_xdp_kfunc_set = {
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.owner = THIS_MODULE,
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.check_set = &nf_ct_xdp_check_kfunc_ids,
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.acquire_set = &nf_ct_acquire_kfunc_ids,
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.release_set = &nf_ct_release_kfunc_ids,
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.ret_null_set = &nf_ct_ret_null_kfunc_ids,
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};
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static const struct btf_kfunc_id_set nf_conntrack_tc_kfunc_set = {
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.owner = THIS_MODULE,
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.check_set = &nf_ct_tc_check_kfunc_ids,
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.acquire_set = &nf_ct_acquire_kfunc_ids,
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.release_set = &nf_ct_release_kfunc_ids,
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.ret_null_set = &nf_ct_ret_null_kfunc_ids,
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};
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int register_nf_conntrack_bpf(void)
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{
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int ret;
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ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &nf_conntrack_xdp_kfunc_set);
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return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &nf_conntrack_tc_kfunc_set);
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}
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