// SPDX-License-Identifier: GPL-2.0-or-later /* * Checksum updating actions * * Copyright (c) 2010 Gregoire Baron <baronchon@n7mm.org> */ #include <linux/types.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/spinlock.h> #include <linux/netlink.h> #include <net/netlink.h> #include <linux/rtnetlink.h> #include <linux/skbuff.h> #include <net/ip.h> #include <net/ipv6.h> #include <net/icmp.h> #include <linux/icmpv6.h> #include <linux/igmp.h> #include <net/tcp.h> #include <net/udp.h> #include <net/ip6_checksum.h> #include <net/sctp/checksum.h> #include <net/act_api.h> #include <net/pkt_cls.h> #include <linux/tc_act/tc_csum.h> #include <net/tc_act/tc_csum.h> static const struct nla_policy csum_policy[TCA_CSUM_MAX + 1] = { [TCA_CSUM_PARMS] = { .len = sizeof(struct tc_csum), }, }; static unsigned int csum_net_id; static struct tc_action_ops act_csum_ops; static int tcf_csum_init(struct net *net, struct nlattr *nla, struct nlattr *est, struct tc_action **a, int ovr, int bind, bool rtnl_held, struct tcf_proto *tp, u32 flags, struct netlink_ext_ack *extack) { struct tc_action_net *tn = net_generic(net, csum_net_id); struct tcf_csum_params *params_new; struct nlattr *tb[TCA_CSUM_MAX + 1]; struct tcf_chain *goto_ch = NULL; struct tc_csum *parm; struct tcf_csum *p; int ret = 0, err; u32 index; if (nla == NULL) return -EINVAL; err = nla_parse_nested_deprecated(tb, TCA_CSUM_MAX, nla, csum_policy, NULL); if (err < 0) return err; if (tb[TCA_CSUM_PARMS] == NULL) return -EINVAL; parm = nla_data(tb[TCA_CSUM_PARMS]); index = parm->index; err = tcf_idr_check_alloc(tn, &index, a, bind); if (!err) { ret = tcf_idr_create_from_flags(tn, index, est, a, &act_csum_ops, bind, flags); if (ret) { tcf_idr_cleanup(tn, index); return ret; } ret = ACT_P_CREATED; } else if (err > 0) { if (bind)/* dont override defaults */ return 0; if (!ovr) { tcf_idr_release(*a, bind); return -EEXIST; } } else { return err; } err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack); if (err < 0) goto release_idr; p = to_tcf_csum(*a); params_new = kzalloc(sizeof(*params_new), GFP_KERNEL); if (unlikely(!params_new)) { err = -ENOMEM; goto put_chain; } params_new->update_flags = parm->update_flags; spin_lock_bh(&p->tcf_lock); goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch); params_new = rcu_replace_pointer(p->params, params_new, lockdep_is_held(&p->tcf_lock)); spin_unlock_bh(&p->tcf_lock); if (goto_ch) tcf_chain_put_by_act(goto_ch); if (params_new) kfree_rcu(params_new, rcu); return ret; put_chain: if (goto_ch) tcf_chain_put_by_act(goto_ch); release_idr: tcf_idr_release(*a, bind); return err; } /** * tcf_csum_skb_nextlayer - Get next layer pointer * @skb: sk_buff to use * @ihl: previous summed headers length * @ipl: complete packet length * @jhl: next header length * * Check the expected next layer availability in the specified sk_buff. * Return the next layer pointer if pass, NULL otherwise. */ static void *tcf_csum_skb_nextlayer(struct sk_buff *skb, unsigned int ihl, unsigned int ipl, unsigned int jhl) { int ntkoff = skb_network_offset(skb); int hl = ihl + jhl; if (!pskb_may_pull(skb, ipl + ntkoff) || (ipl < hl) || skb_try_make_writable(skb, hl + ntkoff)) return NULL; else return (void *)(skb_network_header(skb) + ihl); } static int tcf_csum_ipv4_icmp(struct sk_buff *skb, unsigned int ihl, unsigned int ipl) { struct icmphdr *icmph; icmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmph)); if (icmph == NULL) return 0; icmph->checksum = 0; skb->csum = csum_partial(icmph, ipl - ihl, 0); icmph->checksum = csum_fold(skb->csum); skb->ip_summed = CHECKSUM_NONE; return 1; } static int tcf_csum_ipv4_igmp(struct sk_buff *skb, unsigned int ihl, unsigned int ipl) { struct igmphdr *igmph; igmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*igmph)); if (igmph == NULL) return 0; igmph->csum = 0; skb->csum = csum_partial(igmph, ipl - ihl, 0); igmph->csum = csum_fold(skb->csum); skb->ip_summed = CHECKSUM_NONE; return 1; } static int tcf_csum_ipv6_icmp(struct sk_buff *skb, unsigned int ihl, unsigned int ipl) { struct icmp6hdr *icmp6h; const struct ipv6hdr *ip6h; icmp6h = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmp6h)); if (icmp6h == NULL) return 0; ip6h = ipv6_hdr(skb); icmp6h->icmp6_cksum = 0; skb->csum = csum_partial(icmp6h, ipl - ihl, 0); icmp6h->icmp6_cksum = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, ipl - ihl, IPPROTO_ICMPV6, skb->csum); skb->ip_summed = CHECKSUM_NONE; return 1; } static int tcf_csum_ipv4_tcp(struct sk_buff *skb, unsigned int ihl, unsigned int ipl) { struct tcphdr *tcph; const struct iphdr *iph; if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4) return 1; tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph)); if (tcph == NULL) return 0; iph = ip_hdr(skb); tcph->check = 0; skb->csum = csum_partial(tcph, ipl - ihl, 0); tcph->check = tcp_v4_check(ipl - ihl, iph->saddr, iph->daddr, skb->csum); skb->ip_summed = CHECKSUM_NONE; return 1; } static int tcf_csum_ipv6_tcp(struct sk_buff *skb, unsigned int ihl, unsigned int ipl) { struct tcphdr *tcph; const struct ipv6hdr *ip6h; if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6) return 1; tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph)); if (tcph == NULL) return 0; ip6h = ipv6_hdr(skb); tcph->check = 0; skb->csum = csum_partial(tcph, ipl - ihl, 0); tcph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, ipl - ihl, IPPROTO_TCP, skb->csum); skb->ip_summed = CHECKSUM_NONE; return 1; } static int tcf_csum_ipv4_udp(struct sk_buff *skb, unsigned int ihl, unsigned int ipl, int udplite) { struct udphdr *udph; const struct iphdr *iph; u16 ul; if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_UDP) return 1; /* * Support both UDP and UDPLITE checksum algorithms, Don't use * udph->len to get the real length without any protocol check, * UDPLITE uses udph->len for another thing, * Use iph->tot_len, or just ipl. */ udph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*udph)); if (udph == NULL) return 0; iph = ip_hdr(skb); ul = ntohs(udph->len); if (udplite || udph->check) { udph->check = 0; if (udplite) { if (ul == 0) skb->csum = csum_partial(udph, ipl - ihl, 0); else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl)) skb->csum = csum_partial(udph, ul, 0); else goto ignore_obscure_skb; } else { if (ul != ipl - ihl) goto ignore_obscure_skb; skb->csum = csum_partial(udph, ul, 0); } udph->check = csum_tcpudp_magic(iph->saddr, iph->daddr, ul, iph->protocol, skb->csum); if (!udph->check) udph->check = CSUM_MANGLED_0; } skb->ip_summed = CHECKSUM_NONE; ignore_obscure_skb: return 1; } static int tcf_csum_ipv6_udp(struct sk_buff *skb, unsigned int ihl, unsigned int ipl, int udplite) { struct udphdr *udph; const struct ipv6hdr *ip6h; u16 ul; if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_UDP) return 1; /* * Support both UDP and UDPLITE checksum algorithms, Don't use * udph->len to get the real length without any protocol check, * UDPLITE uses udph->len for another thing, * Use ip6h->payload_len + sizeof(*ip6h) ... , or just ipl. */ udph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*udph)); if (udph == NULL) return 0; ip6h = ipv6_hdr(skb); ul = ntohs(udph->len); udph->check = 0; if (udplite) { if (ul == 0) skb->csum = csum_partial(udph, ipl - ihl, 0); else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl)) skb->csum = csum_partial(udph, ul, 0); else goto ignore_obscure_skb; } else { if (ul != ipl - ihl) goto ignore_obscure_skb; skb->csum = csum_partial(udph, ul, 0); } udph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, ul, udplite ? IPPROTO_UDPLITE : IPPROTO_UDP, skb->csum); if (!udph->check) udph->check = CSUM_MANGLED_0; skb->ip_summed = CHECKSUM_NONE; ignore_obscure_skb: return 1; } static int tcf_csum_sctp(struct sk_buff *skb, unsigned int ihl, unsigned int ipl) { struct sctphdr *sctph; if (skb_is_gso(skb) && skb_is_gso_sctp(skb)) return 1; sctph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*sctph)); if (!sctph) return 0; sctph->checksum = sctp_compute_cksum(skb, skb_network_offset(skb) + ihl); skb->ip_summed = CHECKSUM_NONE; skb->csum_not_inet = 0; return 1; } static int tcf_csum_ipv4(struct sk_buff *skb, u32 update_flags) { const struct iphdr *iph; int ntkoff; ntkoff = skb_network_offset(skb); if (!pskb_may_pull(skb, sizeof(*iph) + ntkoff)) goto fail; iph = ip_hdr(skb); switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) { case IPPROTO_ICMP: if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP) if (!tcf_csum_ipv4_icmp(skb, iph->ihl * 4, ntohs(iph->tot_len))) goto fail; break; case IPPROTO_IGMP: if (update_flags & TCA_CSUM_UPDATE_FLAG_IGMP) if (!tcf_csum_ipv4_igmp(skb, iph->ihl * 4, ntohs(iph->tot_len))) goto fail; break; case IPPROTO_TCP: if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP) if (!tcf_csum_ipv4_tcp(skb, iph->ihl * 4, ntohs(iph->tot_len))) goto fail; break; case IPPROTO_UDP: if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP) if (!tcf_csum_ipv4_udp(skb, iph->ihl * 4, ntohs(iph->tot_len), 0)) goto fail; break; case IPPROTO_UDPLITE: if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE) if (!tcf_csum_ipv4_udp(skb, iph->ihl * 4, ntohs(iph->tot_len), 1)) goto fail; break; case IPPROTO_SCTP: if ((update_flags & TCA_CSUM_UPDATE_FLAG_SCTP) && !tcf_csum_sctp(skb, iph->ihl * 4, ntohs(iph->tot_len))) goto fail; break; } if (update_flags & TCA_CSUM_UPDATE_FLAG_IPV4HDR) { if (skb_try_make_writable(skb, sizeof(*iph) + ntkoff)) goto fail; ip_send_check(ip_hdr(skb)); } return 1; fail: return 0; } static int tcf_csum_ipv6_hopopts(struct ipv6_opt_hdr *ip6xh, unsigned int ixhl, unsigned int *pl) { int off, len, optlen; unsigned char *xh = (void *)ip6xh; off = sizeof(*ip6xh); len = ixhl - off; while (len > 1) { switch (xh[off]) { case IPV6_TLV_PAD1: optlen = 1; break; case IPV6_TLV_JUMBO: optlen = xh[off + 1] + 2; if (optlen != 6 || len < 6 || (off & 3) != 2) /* wrong jumbo option length/alignment */ return 0; *pl = ntohl(*(__be32 *)(xh + off + 2)); goto done; default: optlen = xh[off + 1] + 2; if (optlen > len) /* ignore obscure options */ goto done; break; } off += optlen; len -= optlen; } done: return 1; } static int tcf_csum_ipv6(struct sk_buff *skb, u32 update_flags) { struct ipv6hdr *ip6h; struct ipv6_opt_hdr *ip6xh; unsigned int hl, ixhl; unsigned int pl; int ntkoff; u8 nexthdr; ntkoff = skb_network_offset(skb); hl = sizeof(*ip6h); if (!pskb_may_pull(skb, hl + ntkoff)) goto fail; ip6h = ipv6_hdr(skb); pl = ntohs(ip6h->payload_len); nexthdr = ip6h->nexthdr; do { switch (nexthdr) { case NEXTHDR_FRAGMENT: goto ignore_skb; case NEXTHDR_ROUTING: case NEXTHDR_HOP: case NEXTHDR_DEST: if (!pskb_may_pull(skb, hl + sizeof(*ip6xh) + ntkoff)) goto fail; ip6xh = (void *)(skb_network_header(skb) + hl); ixhl = ipv6_optlen(ip6xh); if (!pskb_may_pull(skb, hl + ixhl + ntkoff)) goto fail; ip6xh = (void *)(skb_network_header(skb) + hl); if ((nexthdr == NEXTHDR_HOP) && !(tcf_csum_ipv6_hopopts(ip6xh, ixhl, &pl))) goto fail; nexthdr = ip6xh->nexthdr; hl += ixhl; break; case IPPROTO_ICMPV6: if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP) if (!tcf_csum_ipv6_icmp(skb, hl, pl + sizeof(*ip6h))) goto fail; goto done; case IPPROTO_TCP: if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP) if (!tcf_csum_ipv6_tcp(skb, hl, pl + sizeof(*ip6h))) goto fail; goto done; case IPPROTO_UDP: if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP) if (!tcf_csum_ipv6_udp(skb, hl, pl + sizeof(*ip6h), 0)) goto fail; goto done; case IPPROTO_UDPLITE: if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE) if (!tcf_csum_ipv6_udp(skb, hl, pl + sizeof(*ip6h), 1)) goto fail; goto done; case IPPROTO_SCTP: if ((update_flags & TCA_CSUM_UPDATE_FLAG_SCTP) && !tcf_csum_sctp(skb, hl, pl + sizeof(*ip6h))) goto fail; goto done; default: goto ignore_skb; } } while (pskb_may_pull(skb, hl + 1 + ntkoff)); done: ignore_skb: return 1; fail: return 0; } static int tcf_csum_act(struct sk_buff *skb, const struct tc_action *a, struct tcf_result *res) { struct tcf_csum *p = to_tcf_csum(a); bool orig_vlan_tag_present = false; unsigned int vlan_hdr_count = 0; struct tcf_csum_params *params; u32 update_flags; __be16 protocol; int action; params = rcu_dereference_bh(p->params); tcf_lastuse_update(&p->tcf_tm); tcf_action_update_bstats(&p->common, skb); action = READ_ONCE(p->tcf_action); if (unlikely(action == TC_ACT_SHOT)) goto drop; update_flags = params->update_flags; protocol = skb_protocol(skb, false); again: switch (protocol) { case cpu_to_be16(ETH_P_IP): if (!tcf_csum_ipv4(skb, update_flags)) goto drop; break; case cpu_to_be16(ETH_P_IPV6): if (!tcf_csum_ipv6(skb, update_flags)) goto drop; break; case cpu_to_be16(ETH_P_8021AD): fallthrough; case cpu_to_be16(ETH_P_8021Q): if (skb_vlan_tag_present(skb) && !orig_vlan_tag_present) { protocol = skb->protocol; orig_vlan_tag_present = true; } else { struct vlan_hdr *vlan = (struct vlan_hdr *)skb->data; protocol = vlan->h_vlan_encapsulated_proto; skb_pull(skb, VLAN_HLEN); skb_reset_network_header(skb); vlan_hdr_count++; } goto again; } out: /* Restore the skb for the pulled VLAN tags */ while (vlan_hdr_count--) { skb_push(skb, VLAN_HLEN); skb_reset_network_header(skb); } return action; drop: tcf_action_inc_drop_qstats(&p->common); action = TC_ACT_SHOT; goto out; } static int tcf_csum_dump(struct sk_buff *skb, struct tc_action *a, int bind, int ref) { unsigned char *b = skb_tail_pointer(skb); struct tcf_csum *p = to_tcf_csum(a); struct tcf_csum_params *params; struct tc_csum opt = { .index = p->tcf_index, .refcnt = refcount_read(&p->tcf_refcnt) - ref, .bindcnt = atomic_read(&p->tcf_bindcnt) - bind, }; struct tcf_t t; spin_lock_bh(&p->tcf_lock); params = rcu_dereference_protected(p->params, lockdep_is_held(&p->tcf_lock)); opt.action = p->tcf_action; opt.update_flags = params->update_flags; if (nla_put(skb, TCA_CSUM_PARMS, sizeof(opt), &opt)) goto nla_put_failure; tcf_tm_dump(&t, &p->tcf_tm); if (nla_put_64bit(skb, TCA_CSUM_TM, sizeof(t), &t, TCA_CSUM_PAD)) goto nla_put_failure; spin_unlock_bh(&p->tcf_lock); return skb->len; nla_put_failure: spin_unlock_bh(&p->tcf_lock); nlmsg_trim(skb, b); return -1; } static void tcf_csum_cleanup(struct tc_action *a) { struct tcf_csum *p = to_tcf_csum(a); struct tcf_csum_params *params; params = rcu_dereference_protected(p->params, 1); if (params) kfree_rcu(params, rcu); } static int tcf_csum_walker(struct net *net, struct sk_buff *skb, struct netlink_callback *cb, int type, const struct tc_action_ops *ops, struct netlink_ext_ack *extack) { struct tc_action_net *tn = net_generic(net, csum_net_id); return tcf_generic_walker(tn, skb, cb, type, ops, extack); } static int tcf_csum_search(struct net *net, struct tc_action **a, u32 index) { struct tc_action_net *tn = net_generic(net, csum_net_id); return tcf_idr_search(tn, a, index); } static size_t tcf_csum_get_fill_size(const struct tc_action *act) { return nla_total_size(sizeof(struct tc_csum)); } static struct tc_action_ops act_csum_ops = { .kind = "csum", .id = TCA_ID_CSUM, .owner = THIS_MODULE, .act = tcf_csum_act, .dump = tcf_csum_dump, .init = tcf_csum_init, .cleanup = tcf_csum_cleanup, .walk = tcf_csum_walker, .lookup = tcf_csum_search, .get_fill_size = tcf_csum_get_fill_size, .size = sizeof(struct tcf_csum), }; static __net_init int csum_init_net(struct net *net) { struct tc_action_net *tn = net_generic(net, csum_net_id); return tc_action_net_init(net, tn, &act_csum_ops); } static void __net_exit csum_exit_net(struct list_head *net_list) { tc_action_net_exit(net_list, csum_net_id); } static struct pernet_operations csum_net_ops = { .init = csum_init_net, .exit_batch = csum_exit_net, .id = &csum_net_id, .size = sizeof(struct tc_action_net), }; MODULE_DESCRIPTION("Checksum updating actions"); MODULE_LICENSE("GPL"); static int __init csum_init_module(void) { return tcf_register_action(&act_csum_ops, &csum_net_ops); } static void __exit csum_cleanup_module(void) { tcf_unregister_action(&act_csum_ops, &csum_net_ops); } module_init(csum_init_module); module_exit(csum_cleanup_module);