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-rw-r--r--net/core/lwt_bpf.c657
1 files changed, 657 insertions, 0 deletions
diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c
new file mode 100644
index 000000000..4a0797f0a
--- /dev/null
+++ b/net/core/lwt_bpf.c
@@ -0,0 +1,657 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2016 Thomas Graf <tgraf@tgraf.ch>
+ */
+
+#include <linux/filter.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/types.h>
+#include <linux/bpf.h>
+#include <net/lwtunnel.h>
+#include <net/gre.h>
+#include <net/ip6_route.h>
+#include <net/ipv6_stubs.h>
+
+struct bpf_lwt_prog {
+ struct bpf_prog *prog;
+ char *name;
+};
+
+struct bpf_lwt {
+ struct bpf_lwt_prog in;
+ struct bpf_lwt_prog out;
+ struct bpf_lwt_prog xmit;
+ int family;
+};
+
+#define MAX_PROG_NAME 256
+
+static inline struct bpf_lwt *bpf_lwt_lwtunnel(struct lwtunnel_state *lwt)
+{
+ return (struct bpf_lwt *)lwt->data;
+}
+
+#define NO_REDIRECT false
+#define CAN_REDIRECT true
+
+static int run_lwt_bpf(struct sk_buff *skb, struct bpf_lwt_prog *lwt,
+ struct dst_entry *dst, bool can_redirect)
+{
+ int ret;
+
+ /* Migration disable and BH disable are needed to protect per-cpu
+ * redirect_info between BPF prog and skb_do_redirect().
+ */
+ migrate_disable();
+ local_bh_disable();
+ bpf_compute_data_pointers(skb);
+ ret = bpf_prog_run_save_cb(lwt->prog, skb);
+
+ switch (ret) {
+ case BPF_OK:
+ case BPF_LWT_REROUTE:
+ break;
+
+ case BPF_REDIRECT:
+ if (unlikely(!can_redirect)) {
+ pr_warn_once("Illegal redirect return code in prog %s\n",
+ lwt->name ? : "<unknown>");
+ ret = BPF_OK;
+ } else {
+ skb_reset_mac_header(skb);
+ skb_do_redirect(skb);
+ ret = BPF_REDIRECT;
+ }
+ break;
+
+ case BPF_DROP:
+ kfree_skb(skb);
+ ret = -EPERM;
+ break;
+
+ default:
+ pr_warn_once("bpf-lwt: Illegal return value %u, expect packet loss\n", ret);
+ kfree_skb(skb);
+ ret = -EINVAL;
+ break;
+ }
+
+ local_bh_enable();
+ migrate_enable();
+
+ return ret;
+}
+
+static int bpf_lwt_input_reroute(struct sk_buff *skb)
+{
+ int err = -EINVAL;
+
+ if (skb->protocol == htons(ETH_P_IP)) {
+ struct net_device *dev = skb_dst(skb)->dev;
+ struct iphdr *iph = ip_hdr(skb);
+
+ dev_hold(dev);
+ skb_dst_drop(skb);
+ err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
+ iph->tos, dev);
+ dev_put(dev);
+ } else if (skb->protocol == htons(ETH_P_IPV6)) {
+ skb_dst_drop(skb);
+ err = ipv6_stub->ipv6_route_input(skb);
+ } else {
+ err = -EAFNOSUPPORT;
+ }
+
+ if (err)
+ goto err;
+ return dst_input(skb);
+
+err:
+ kfree_skb(skb);
+ return err;
+}
+
+static int bpf_input(struct sk_buff *skb)
+{
+ struct dst_entry *dst = skb_dst(skb);
+ struct bpf_lwt *bpf;
+ int ret;
+
+ bpf = bpf_lwt_lwtunnel(dst->lwtstate);
+ if (bpf->in.prog) {
+ ret = run_lwt_bpf(skb, &bpf->in, dst, NO_REDIRECT);
+ if (ret < 0)
+ return ret;
+ if (ret == BPF_LWT_REROUTE)
+ return bpf_lwt_input_reroute(skb);
+ }
+
+ if (unlikely(!dst->lwtstate->orig_input)) {
+ kfree_skb(skb);
+ return -EINVAL;
+ }
+
+ return dst->lwtstate->orig_input(skb);
+}
+
+static int bpf_output(struct net *net, struct sock *sk, struct sk_buff *skb)
+{
+ struct dst_entry *dst = skb_dst(skb);
+ struct bpf_lwt *bpf;
+ int ret;
+
+ bpf = bpf_lwt_lwtunnel(dst->lwtstate);
+ if (bpf->out.prog) {
+ ret = run_lwt_bpf(skb, &bpf->out, dst, NO_REDIRECT);
+ if (ret < 0)
+ return ret;
+ }
+
+ if (unlikely(!dst->lwtstate->orig_output)) {
+ pr_warn_once("orig_output not set on dst for prog %s\n",
+ bpf->out.name);
+ kfree_skb(skb);
+ return -EINVAL;
+ }
+
+ return dst->lwtstate->orig_output(net, sk, skb);
+}
+
+static int xmit_check_hhlen(struct sk_buff *skb, int hh_len)
+{
+ if (skb_headroom(skb) < hh_len) {
+ int nhead = HH_DATA_ALIGN(hh_len - skb_headroom(skb));
+
+ if (pskb_expand_head(skb, nhead, 0, GFP_ATOMIC))
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static int bpf_lwt_xmit_reroute(struct sk_buff *skb)
+{
+ struct net_device *l3mdev = l3mdev_master_dev_rcu(skb_dst(skb)->dev);
+ int oif = l3mdev ? l3mdev->ifindex : 0;
+ struct dst_entry *dst = NULL;
+ int err = -EAFNOSUPPORT;
+ struct sock *sk;
+ struct net *net;
+ bool ipv4;
+
+ if (skb->protocol == htons(ETH_P_IP))
+ ipv4 = true;
+ else if (skb->protocol == htons(ETH_P_IPV6))
+ ipv4 = false;
+ else
+ goto err;
+
+ sk = sk_to_full_sk(skb->sk);
+ if (sk) {
+ if (sk->sk_bound_dev_if)
+ oif = sk->sk_bound_dev_if;
+ net = sock_net(sk);
+ } else {
+ net = dev_net(skb_dst(skb)->dev);
+ }
+
+ if (ipv4) {
+ struct iphdr *iph = ip_hdr(skb);
+ struct flowi4 fl4 = {};
+ struct rtable *rt;
+
+ fl4.flowi4_oif = oif;
+ fl4.flowi4_mark = skb->mark;
+ fl4.flowi4_uid = sock_net_uid(net, sk);
+ fl4.flowi4_tos = RT_TOS(iph->tos);
+ fl4.flowi4_flags = FLOWI_FLAG_ANYSRC;
+ fl4.flowi4_proto = iph->protocol;
+ fl4.daddr = iph->daddr;
+ fl4.saddr = iph->saddr;
+
+ rt = ip_route_output_key(net, &fl4);
+ if (IS_ERR(rt)) {
+ err = PTR_ERR(rt);
+ goto err;
+ }
+ dst = &rt->dst;
+ } else {
+ struct ipv6hdr *iph6 = ipv6_hdr(skb);
+ struct flowi6 fl6 = {};
+
+ fl6.flowi6_oif = oif;
+ fl6.flowi6_mark = skb->mark;
+ fl6.flowi6_uid = sock_net_uid(net, sk);
+ fl6.flowlabel = ip6_flowinfo(iph6);
+ fl6.flowi6_proto = iph6->nexthdr;
+ fl6.daddr = iph6->daddr;
+ fl6.saddr = iph6->saddr;
+
+ dst = ipv6_stub->ipv6_dst_lookup_flow(net, skb->sk, &fl6, NULL);
+ if (IS_ERR(dst)) {
+ err = PTR_ERR(dst);
+ goto err;
+ }
+ }
+ if (unlikely(dst->error)) {
+ err = dst->error;
+ dst_release(dst);
+ goto err;
+ }
+
+ /* Although skb header was reserved in bpf_lwt_push_ip_encap(), it
+ * was done for the previous dst, so we are doing it here again, in
+ * case the new dst needs much more space. The call below is a noop
+ * if there is enough header space in skb.
+ */
+ err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
+ if (unlikely(err))
+ goto err;
+
+ skb_dst_drop(skb);
+ skb_dst_set(skb, dst);
+
+ err = dst_output(dev_net(skb_dst(skb)->dev), skb->sk, skb);
+ if (unlikely(err))
+ return net_xmit_errno(err);
+
+ /* ip[6]_finish_output2 understand LWTUNNEL_XMIT_DONE */
+ return LWTUNNEL_XMIT_DONE;
+
+err:
+ kfree_skb(skb);
+ return err;
+}
+
+static int bpf_xmit(struct sk_buff *skb)
+{
+ struct dst_entry *dst = skb_dst(skb);
+ struct bpf_lwt *bpf;
+
+ bpf = bpf_lwt_lwtunnel(dst->lwtstate);
+ if (bpf->xmit.prog) {
+ int hh_len = dst->dev->hard_header_len;
+ __be16 proto = skb->protocol;
+ int ret;
+
+ ret = run_lwt_bpf(skb, &bpf->xmit, dst, CAN_REDIRECT);
+ switch (ret) {
+ case BPF_OK:
+ /* If the header changed, e.g. via bpf_lwt_push_encap,
+ * BPF_LWT_REROUTE below should have been used if the
+ * protocol was also changed.
+ */
+ if (skb->protocol != proto) {
+ kfree_skb(skb);
+ return -EINVAL;
+ }
+ /* If the header was expanded, headroom might be too
+ * small for L2 header to come, expand as needed.
+ */
+ ret = xmit_check_hhlen(skb, hh_len);
+ if (unlikely(ret))
+ return ret;
+
+ return LWTUNNEL_XMIT_CONTINUE;
+ case BPF_REDIRECT:
+ return LWTUNNEL_XMIT_DONE;
+ case BPF_LWT_REROUTE:
+ return bpf_lwt_xmit_reroute(skb);
+ default:
+ return ret;
+ }
+ }
+
+ return LWTUNNEL_XMIT_CONTINUE;
+}
+
+static void bpf_lwt_prog_destroy(struct bpf_lwt_prog *prog)
+{
+ if (prog->prog)
+ bpf_prog_put(prog->prog);
+
+ kfree(prog->name);
+}
+
+static void bpf_destroy_state(struct lwtunnel_state *lwt)
+{
+ struct bpf_lwt *bpf = bpf_lwt_lwtunnel(lwt);
+
+ bpf_lwt_prog_destroy(&bpf->in);
+ bpf_lwt_prog_destroy(&bpf->out);
+ bpf_lwt_prog_destroy(&bpf->xmit);
+}
+
+static const struct nla_policy bpf_prog_policy[LWT_BPF_PROG_MAX + 1] = {
+ [LWT_BPF_PROG_FD] = { .type = NLA_U32, },
+ [LWT_BPF_PROG_NAME] = { .type = NLA_NUL_STRING,
+ .len = MAX_PROG_NAME },
+};
+
+static int bpf_parse_prog(struct nlattr *attr, struct bpf_lwt_prog *prog,
+ enum bpf_prog_type type)
+{
+ struct nlattr *tb[LWT_BPF_PROG_MAX + 1];
+ struct bpf_prog *p;
+ int ret;
+ u32 fd;
+
+ ret = nla_parse_nested_deprecated(tb, LWT_BPF_PROG_MAX, attr,
+ bpf_prog_policy, NULL);
+ if (ret < 0)
+ return ret;
+
+ if (!tb[LWT_BPF_PROG_FD] || !tb[LWT_BPF_PROG_NAME])
+ return -EINVAL;
+
+ prog->name = nla_memdup(tb[LWT_BPF_PROG_NAME], GFP_ATOMIC);
+ if (!prog->name)
+ return -ENOMEM;
+
+ fd = nla_get_u32(tb[LWT_BPF_PROG_FD]);
+ p = bpf_prog_get_type(fd, type);
+ if (IS_ERR(p))
+ return PTR_ERR(p);
+
+ prog->prog = p;
+
+ return 0;
+}
+
+static const struct nla_policy bpf_nl_policy[LWT_BPF_MAX + 1] = {
+ [LWT_BPF_IN] = { .type = NLA_NESTED, },
+ [LWT_BPF_OUT] = { .type = NLA_NESTED, },
+ [LWT_BPF_XMIT] = { .type = NLA_NESTED, },
+ [LWT_BPF_XMIT_HEADROOM] = { .type = NLA_U32 },
+};
+
+static int bpf_build_state(struct net *net, struct nlattr *nla,
+ unsigned int family, const void *cfg,
+ struct lwtunnel_state **ts,
+ struct netlink_ext_ack *extack)
+{
+ struct nlattr *tb[LWT_BPF_MAX + 1];
+ struct lwtunnel_state *newts;
+ struct bpf_lwt *bpf;
+ int ret;
+
+ if (family != AF_INET && family != AF_INET6)
+ return -EAFNOSUPPORT;
+
+ ret = nla_parse_nested_deprecated(tb, LWT_BPF_MAX, nla, bpf_nl_policy,
+ extack);
+ if (ret < 0)
+ return ret;
+
+ if (!tb[LWT_BPF_IN] && !tb[LWT_BPF_OUT] && !tb[LWT_BPF_XMIT])
+ return -EINVAL;
+
+ newts = lwtunnel_state_alloc(sizeof(*bpf));
+ if (!newts)
+ return -ENOMEM;
+
+ newts->type = LWTUNNEL_ENCAP_BPF;
+ bpf = bpf_lwt_lwtunnel(newts);
+
+ if (tb[LWT_BPF_IN]) {
+ newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT;
+ ret = bpf_parse_prog(tb[LWT_BPF_IN], &bpf->in,
+ BPF_PROG_TYPE_LWT_IN);
+ if (ret < 0)
+ goto errout;
+ }
+
+ if (tb[LWT_BPF_OUT]) {
+ newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
+ ret = bpf_parse_prog(tb[LWT_BPF_OUT], &bpf->out,
+ BPF_PROG_TYPE_LWT_OUT);
+ if (ret < 0)
+ goto errout;
+ }
+
+ if (tb[LWT_BPF_XMIT]) {
+ newts->flags |= LWTUNNEL_STATE_XMIT_REDIRECT;
+ ret = bpf_parse_prog(tb[LWT_BPF_XMIT], &bpf->xmit,
+ BPF_PROG_TYPE_LWT_XMIT);
+ if (ret < 0)
+ goto errout;
+ }
+
+ if (tb[LWT_BPF_XMIT_HEADROOM]) {
+ u32 headroom = nla_get_u32(tb[LWT_BPF_XMIT_HEADROOM]);
+
+ if (headroom > LWT_BPF_MAX_HEADROOM) {
+ ret = -ERANGE;
+ goto errout;
+ }
+
+ newts->headroom = headroom;
+ }
+
+ bpf->family = family;
+ *ts = newts;
+
+ return 0;
+
+errout:
+ bpf_destroy_state(newts);
+ kfree(newts);
+ return ret;
+}
+
+static int bpf_fill_lwt_prog(struct sk_buff *skb, int attr,
+ struct bpf_lwt_prog *prog)
+{
+ struct nlattr *nest;
+
+ if (!prog->prog)
+ return 0;
+
+ nest = nla_nest_start_noflag(skb, attr);
+ if (!nest)
+ return -EMSGSIZE;
+
+ if (prog->name &&
+ nla_put_string(skb, LWT_BPF_PROG_NAME, prog->name))
+ return -EMSGSIZE;
+
+ return nla_nest_end(skb, nest);
+}
+
+static int bpf_fill_encap_info(struct sk_buff *skb, struct lwtunnel_state *lwt)
+{
+ struct bpf_lwt *bpf = bpf_lwt_lwtunnel(lwt);
+
+ if (bpf_fill_lwt_prog(skb, LWT_BPF_IN, &bpf->in) < 0 ||
+ bpf_fill_lwt_prog(skb, LWT_BPF_OUT, &bpf->out) < 0 ||
+ bpf_fill_lwt_prog(skb, LWT_BPF_XMIT, &bpf->xmit) < 0)
+ return -EMSGSIZE;
+
+ return 0;
+}
+
+static int bpf_encap_nlsize(struct lwtunnel_state *lwtstate)
+{
+ int nest_len = nla_total_size(sizeof(struct nlattr)) +
+ nla_total_size(MAX_PROG_NAME) + /* LWT_BPF_PROG_NAME */
+ 0;
+
+ return nest_len + /* LWT_BPF_IN */
+ nest_len + /* LWT_BPF_OUT */
+ nest_len + /* LWT_BPF_XMIT */
+ 0;
+}
+
+static int bpf_lwt_prog_cmp(struct bpf_lwt_prog *a, struct bpf_lwt_prog *b)
+{
+ /* FIXME:
+ * The LWT state is currently rebuilt for delete requests which
+ * results in a new bpf_prog instance. Comparing names for now.
+ */
+ if (!a->name && !b->name)
+ return 0;
+
+ if (!a->name || !b->name)
+ return 1;
+
+ return strcmp(a->name, b->name);
+}
+
+static int bpf_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
+{
+ struct bpf_lwt *a_bpf = bpf_lwt_lwtunnel(a);
+ struct bpf_lwt *b_bpf = bpf_lwt_lwtunnel(b);
+
+ return bpf_lwt_prog_cmp(&a_bpf->in, &b_bpf->in) ||
+ bpf_lwt_prog_cmp(&a_bpf->out, &b_bpf->out) ||
+ bpf_lwt_prog_cmp(&a_bpf->xmit, &b_bpf->xmit);
+}
+
+static const struct lwtunnel_encap_ops bpf_encap_ops = {
+ .build_state = bpf_build_state,
+ .destroy_state = bpf_destroy_state,
+ .input = bpf_input,
+ .output = bpf_output,
+ .xmit = bpf_xmit,
+ .fill_encap = bpf_fill_encap_info,
+ .get_encap_size = bpf_encap_nlsize,
+ .cmp_encap = bpf_encap_cmp,
+ .owner = THIS_MODULE,
+};
+
+static int handle_gso_type(struct sk_buff *skb, unsigned int gso_type,
+ int encap_len)
+{
+ struct skb_shared_info *shinfo = skb_shinfo(skb);
+
+ gso_type |= SKB_GSO_DODGY;
+ shinfo->gso_type |= gso_type;
+ skb_decrease_gso_size(shinfo, encap_len);
+ shinfo->gso_segs = 0;
+ return 0;
+}
+
+static int handle_gso_encap(struct sk_buff *skb, bool ipv4, int encap_len)
+{
+ int next_hdr_offset;
+ void *next_hdr;
+ __u8 protocol;
+
+ /* SCTP and UDP_L4 gso need more nuanced handling than what
+ * handle_gso_type() does above: skb_decrease_gso_size() is not enough.
+ * So at the moment only TCP GSO packets are let through.
+ */
+ if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
+ return -ENOTSUPP;
+
+ if (ipv4) {
+ protocol = ip_hdr(skb)->protocol;
+ next_hdr_offset = sizeof(struct iphdr);
+ next_hdr = skb_network_header(skb) + next_hdr_offset;
+ } else {
+ protocol = ipv6_hdr(skb)->nexthdr;
+ next_hdr_offset = sizeof(struct ipv6hdr);
+ next_hdr = skb_network_header(skb) + next_hdr_offset;
+ }
+
+ switch (protocol) {
+ case IPPROTO_GRE:
+ next_hdr_offset += sizeof(struct gre_base_hdr);
+ if (next_hdr_offset > encap_len)
+ return -EINVAL;
+
+ if (((struct gre_base_hdr *)next_hdr)->flags & GRE_CSUM)
+ return handle_gso_type(skb, SKB_GSO_GRE_CSUM,
+ encap_len);
+ return handle_gso_type(skb, SKB_GSO_GRE, encap_len);
+
+ case IPPROTO_UDP:
+ next_hdr_offset += sizeof(struct udphdr);
+ if (next_hdr_offset > encap_len)
+ return -EINVAL;
+
+ if (((struct udphdr *)next_hdr)->check)
+ return handle_gso_type(skb, SKB_GSO_UDP_TUNNEL_CSUM,
+ encap_len);
+ return handle_gso_type(skb, SKB_GSO_UDP_TUNNEL, encap_len);
+
+ case IPPROTO_IP:
+ case IPPROTO_IPV6:
+ if (ipv4)
+ return handle_gso_type(skb, SKB_GSO_IPXIP4, encap_len);
+ else
+ return handle_gso_type(skb, SKB_GSO_IPXIP6, encap_len);
+
+ default:
+ return -EPROTONOSUPPORT;
+ }
+}
+
+int bpf_lwt_push_ip_encap(struct sk_buff *skb, void *hdr, u32 len, bool ingress)
+{
+ struct iphdr *iph;
+ bool ipv4;
+ int err;
+
+ if (unlikely(len < sizeof(struct iphdr) || len > LWT_BPF_MAX_HEADROOM))
+ return -EINVAL;
+
+ /* validate protocol and length */
+ iph = (struct iphdr *)hdr;
+ if (iph->version == 4) {
+ ipv4 = true;
+ if (unlikely(len < iph->ihl * 4))
+ return -EINVAL;
+ } else if (iph->version == 6) {
+ ipv4 = false;
+ if (unlikely(len < sizeof(struct ipv6hdr)))
+ return -EINVAL;
+ } else {
+ return -EINVAL;
+ }
+
+ if (ingress)
+ err = skb_cow_head(skb, len + skb->mac_len);
+ else
+ err = skb_cow_head(skb,
+ len + LL_RESERVED_SPACE(skb_dst(skb)->dev));
+ if (unlikely(err))
+ return err;
+
+ /* push the encap headers and fix pointers */
+ skb_reset_inner_headers(skb);
+ skb_reset_inner_mac_header(skb); /* mac header is not yet set */
+ skb_set_inner_protocol(skb, skb->protocol);
+ skb->encapsulation = 1;
+ skb_push(skb, len);
+ if (ingress)
+ skb_postpush_rcsum(skb, iph, len);
+ skb_reset_network_header(skb);
+ memcpy(skb_network_header(skb), hdr, len);
+ bpf_compute_data_pointers(skb);
+ skb_clear_hash(skb);
+
+ if (ipv4) {
+ skb->protocol = htons(ETH_P_IP);
+ iph = ip_hdr(skb);
+
+ if (!iph->check)
+ iph->check = ip_fast_csum((unsigned char *)iph,
+ iph->ihl);
+ } else {
+ skb->protocol = htons(ETH_P_IPV6);
+ }
+
+ if (skb_is_gso(skb))
+ return handle_gso_encap(skb, ipv4, len);
+
+ return 0;
+}
+
+static int __init bpf_lwt_init(void)
+{
+ return lwtunnel_encap_add_ops(&bpf_encap_ops, LWTUNNEL_ENCAP_BPF);
+}
+
+subsys_initcall(bpf_lwt_init)
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-18 14:53:17 +0000