From f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae Mon Sep 17 00:00:00 2001 From: Eyal Birger Date: Mon, 27 May 2024 20:29:14 -0700 Subject: [PATCH] xfrm: support sending NAT keepalives in ESP in UDP states Add the ability to send out RFC-3948 NAT keepalives from the xfrm stack. To use, Userspace sets an XFRM_NAT_KEEPALIVE_INTERVAL integer property when creating XFRM outbound states which denotes the number of seconds between keepalive messages. Keepalive messages are sent from a per net delayed work which iterates over the xfrm states. The logic is guarded by the xfrm state spinlock due to the xfrm state walk iterator. Possible future enhancements: - Adding counters to keep track of sent keepalives. - deduplicate NAT keepalives between states sharing the same nat keepalive parameters. - provisioning hardware offloads for devices capable of implementing this. - revise xfrm state list to use an rcu list in order to avoid running this under spinlock. Suggested-by: Paul Wouters Tested-by: Paul Wouters Tested-by: Antony Antony Signed-off-by: Eyal Birger Signed-off-by: Steffen Klassert --- include/net/ipv6_stubs.h | 3 + include/net/netns/xfrm.h | 1 + include/net/xfrm.h | 10 ++ include/uapi/linux/xfrm.h | 1 + net/ipv6/af_inet6.c | 1 + net/ipv6/xfrm6_policy.c | 7 + net/xfrm/Makefile | 3 +- net/xfrm/xfrm_compat.c | 6 +- net/xfrm/xfrm_nat_keepalive.c | 292 ++++++++++++++++++++++++++++++++++ net/xfrm/xfrm_policy.c | 8 + net/xfrm/xfrm_state.c | 17 ++ net/xfrm/xfrm_user.c | 15 ++ 12 files changed, 361 insertions(+), 3 deletions(-) create mode 100644 net/xfrm/xfrm_nat_keepalive.c diff --git a/include/net/ipv6_stubs.h b/include/net/ipv6_stubs.h index 485c39a89866..11cefd50704d 100644 --- a/include/net/ipv6_stubs.h +++ b/include/net/ipv6_stubs.h @@ -9,6 +9,7 @@ #include #include #include +#include /* structs from net/ip6_fib.h */ struct fib6_info; @@ -72,6 +73,8 @@ struct ipv6_stub { int (*output)(struct net *, struct sock *, struct sk_buff *)); struct net_device *(*ipv6_dev_find)(struct net *net, const struct in6_addr *addr, struct net_device *dev); + int (*ip6_xmit)(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6, + __u32 mark, struct ipv6_txoptions *opt, int tclass, u32 priority); }; extern const struct ipv6_stub *ipv6_stub __read_mostly; diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h index 423b52eca908..d489d9250bff 100644 --- a/include/net/netns/xfrm.h +++ b/include/net/netns/xfrm.h @@ -83,6 +83,7 @@ struct netns_xfrm { spinlock_t xfrm_policy_lock; struct mutex xfrm_cfg_mutex; + struct delayed_work nat_keepalive_work; }; #endif diff --git a/include/net/xfrm.h b/include/net/xfrm.h index 77ebf5bcf0b9..46a214a76081 100644 --- a/include/net/xfrm.h +++ b/include/net/xfrm.h @@ -229,6 +229,10 @@ struct xfrm_state { struct xfrm_encap_tmpl *encap; struct sock __rcu *encap_sk; + /* NAT keepalive */ + u32 nat_keepalive_interval; /* seconds */ + time64_t nat_keepalive_expiration; + /* Data for care-of address */ xfrm_address_t *coaddr; @@ -2203,4 +2207,10 @@ static inline int register_xfrm_state_bpf(void) } #endif +int xfrm_nat_keepalive_init(unsigned short family); +void xfrm_nat_keepalive_fini(unsigned short family); +int xfrm_nat_keepalive_net_init(struct net *net); +int xfrm_nat_keepalive_net_fini(struct net *net); +void xfrm_nat_keepalive_state_updated(struct xfrm_state *x); + #endif /* _NET_XFRM_H */ diff --git a/include/uapi/linux/xfrm.h b/include/uapi/linux/xfrm.h index d950d02ab791..f28701500714 100644 --- a/include/uapi/linux/xfrm.h +++ b/include/uapi/linux/xfrm.h @@ -321,6 +321,7 @@ enum xfrm_attr_type_t { XFRMA_IF_ID, /* __u32 */ XFRMA_MTIMER_THRESH, /* __u32 in seconds for input SA */ XFRMA_SA_DIR, /* __u8 */ + XFRMA_NAT_KEEPALIVE_INTERVAL, /* __u32 in seconds for NAT keepalive */ __XFRMA_MAX #define XFRMA_OUTPUT_MARK XFRMA_SET_MARK /* Compatibility */ diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c index 8041dc181bd4..2b893858b9a9 100644 --- a/net/ipv6/af_inet6.c +++ b/net/ipv6/af_inet6.c @@ -1060,6 +1060,7 @@ static const struct ipv6_stub ipv6_stub_impl = { .nd_tbl = &nd_tbl, .ipv6_fragment = ip6_fragment, .ipv6_dev_find = ipv6_dev_find, + .ip6_xmit = ip6_xmit, }; static const struct ipv6_bpf_stub ipv6_bpf_stub_impl = { diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c index cc885d3aa9e5..6837ff05f11a 100644 --- a/net/ipv6/xfrm6_policy.c +++ b/net/ipv6/xfrm6_policy.c @@ -284,8 +284,14 @@ int __init xfrm6_init(void) ret = register_pernet_subsys(&xfrm6_net_ops); if (ret) goto out_protocol; + + ret = xfrm_nat_keepalive_init(AF_INET6); + if (ret) + goto out_nat_keepalive; out: return ret; +out_nat_keepalive: + unregister_pernet_subsys(&xfrm6_net_ops); out_protocol: xfrm6_protocol_fini(); out_state: @@ -297,6 +303,7 @@ out_policy: void xfrm6_fini(void) { + xfrm_nat_keepalive_fini(AF_INET6); unregister_pernet_subsys(&xfrm6_net_ops); xfrm6_protocol_fini(); xfrm6_policy_fini(); diff --git a/net/xfrm/Makefile b/net/xfrm/Makefile index 547cec77ba03..512e0b2f8514 100644 --- a/net/xfrm/Makefile +++ b/net/xfrm/Makefile @@ -13,7 +13,8 @@ endif obj-$(CONFIG_XFRM) := xfrm_policy.o xfrm_state.o xfrm_hash.o \ xfrm_input.o xfrm_output.o \ - xfrm_sysctl.o xfrm_replay.o xfrm_device.o + xfrm_sysctl.o xfrm_replay.o xfrm_device.o \ + xfrm_nat_keepalive.o obj-$(CONFIG_XFRM_STATISTICS) += xfrm_proc.o obj-$(CONFIG_XFRM_ALGO) += xfrm_algo.o obj-$(CONFIG_XFRM_USER) += xfrm_user.o diff --git a/net/xfrm/xfrm_compat.c b/net/xfrm/xfrm_compat.c index 703d4172c7d7..91357ccaf4af 100644 --- a/net/xfrm/xfrm_compat.c +++ b/net/xfrm/xfrm_compat.c @@ -131,6 +131,7 @@ static const struct nla_policy compat_policy[XFRMA_MAX+1] = { [XFRMA_IF_ID] = { .type = NLA_U32 }, [XFRMA_MTIMER_THRESH] = { .type = NLA_U32 }, [XFRMA_SA_DIR] = NLA_POLICY_RANGE(NLA_U8, XFRM_SA_DIR_IN, XFRM_SA_DIR_OUT), + [XFRMA_NAT_KEEPALIVE_INTERVAL] = { .type = NLA_U32 }, }; static struct nlmsghdr *xfrm_nlmsg_put_compat(struct sk_buff *skb, @@ -280,9 +281,10 @@ static int xfrm_xlate64_attr(struct sk_buff *dst, const struct nlattr *src) case XFRMA_IF_ID: case XFRMA_MTIMER_THRESH: case XFRMA_SA_DIR: + case XFRMA_NAT_KEEPALIVE_INTERVAL: return xfrm_nla_cpy(dst, src, nla_len(src)); default: - BUILD_BUG_ON(XFRMA_MAX != XFRMA_SA_DIR); + BUILD_BUG_ON(XFRMA_MAX != XFRMA_NAT_KEEPALIVE_INTERVAL); pr_warn_once("unsupported nla_type %d\n", src->nla_type); return -EOPNOTSUPP; } @@ -437,7 +439,7 @@ static int xfrm_xlate32_attr(void *dst, const struct nlattr *nla, int err; if (type > XFRMA_MAX) { - BUILD_BUG_ON(XFRMA_MAX != XFRMA_SA_DIR); + BUILD_BUG_ON(XFRMA_MAX != XFRMA_NAT_KEEPALIVE_INTERVAL); NL_SET_ERR_MSG(extack, "Bad attribute"); return -EOPNOTSUPP; } diff --git a/net/xfrm/xfrm_nat_keepalive.c b/net/xfrm/xfrm_nat_keepalive.c new file mode 100644 index 000000000000..82f0a301683f --- /dev/null +++ b/net/xfrm/xfrm_nat_keepalive.c @@ -0,0 +1,292 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * xfrm_nat_keepalive.c + * + * (c) 2024 Eyal Birger + */ + +#include +#include +#include + +static DEFINE_PER_CPU(struct sock *, nat_keepalive_sk_ipv4); +#if IS_ENABLED(CONFIG_IPV6) +static DEFINE_PER_CPU(struct sock *, nat_keepalive_sk_ipv6); +#endif + +struct nat_keepalive { + struct net *net; + u16 family; + xfrm_address_t saddr; + xfrm_address_t daddr; + __be16 encap_sport; + __be16 encap_dport; + __u32 smark; +}; + +static void nat_keepalive_init(struct nat_keepalive *ka, struct xfrm_state *x) +{ + ka->net = xs_net(x); + ka->family = x->props.family; + ka->saddr = x->props.saddr; + ka->daddr = x->id.daddr; + ka->encap_sport = x->encap->encap_sport; + ka->encap_dport = x->encap->encap_dport; + ka->smark = xfrm_smark_get(0, x); +} + +static int nat_keepalive_send_ipv4(struct sk_buff *skb, + struct nat_keepalive *ka) +{ + struct net *net = ka->net; + struct flowi4 fl4; + struct rtable *rt; + struct sock *sk; + __u8 tos = 0; + int err; + + flowi4_init_output(&fl4, 0 /* oif */, skb->mark, tos, + RT_SCOPE_UNIVERSE, IPPROTO_UDP, 0, + ka->daddr.a4, ka->saddr.a4, ka->encap_dport, + ka->encap_sport, sock_net_uid(net, NULL)); + + rt = ip_route_output_key(net, &fl4); + if (IS_ERR(rt)) + return PTR_ERR(rt); + + skb_dst_set(skb, &rt->dst); + + sk = *this_cpu_ptr(&nat_keepalive_sk_ipv4); + sock_net_set(sk, net); + err = ip_build_and_send_pkt(skb, sk, fl4.saddr, fl4.daddr, NULL, tos); + sock_net_set(sk, &init_net); + return err; +} + +#if IS_ENABLED(CONFIG_IPV6) +static int nat_keepalive_send_ipv6(struct sk_buff *skb, + struct nat_keepalive *ka, + struct udphdr *uh) +{ + struct net *net = ka->net; + struct dst_entry *dst; + struct flowi6 fl6; + struct sock *sk; + __wsum csum; + int err; + + csum = skb_checksum(skb, 0, skb->len, 0); + uh->check = csum_ipv6_magic(&ka->saddr.in6, &ka->daddr.in6, + skb->len, IPPROTO_UDP, csum); + if (uh->check == 0) + uh->check = CSUM_MANGLED_0; + + memset(&fl6, 0, sizeof(fl6)); + fl6.flowi6_mark = skb->mark; + fl6.saddr = ka->saddr.in6; + fl6.daddr = ka->daddr.in6; + fl6.flowi6_proto = IPPROTO_UDP; + fl6.fl6_sport = ka->encap_sport; + fl6.fl6_dport = ka->encap_dport; + + sk = *this_cpu_ptr(&nat_keepalive_sk_ipv6); + sock_net_set(sk, net); + dst = ipv6_stub->ipv6_dst_lookup_flow(net, sk, &fl6, NULL); + if (IS_ERR(dst)) + return PTR_ERR(dst); + + skb_dst_set(skb, dst); + err = ipv6_stub->ip6_xmit(sk, skb, &fl6, skb->mark, NULL, 0, 0); + sock_net_set(sk, &init_net); + return err; +} +#endif + +static void nat_keepalive_send(struct nat_keepalive *ka) +{ + const int nat_ka_hdrs_len = max(sizeof(struct iphdr), + sizeof(struct ipv6hdr)) + + sizeof(struct udphdr); + const u8 nat_ka_payload = 0xFF; + int err = -EAFNOSUPPORT; + struct sk_buff *skb; + struct udphdr *uh; + + skb = alloc_skb(nat_ka_hdrs_len + sizeof(nat_ka_payload), GFP_ATOMIC); + if (unlikely(!skb)) + return; + + skb_reserve(skb, nat_ka_hdrs_len); + + skb_put_u8(skb, nat_ka_payload); + + uh = skb_push(skb, sizeof(*uh)); + uh->source = ka->encap_sport; + uh->dest = ka->encap_dport; + uh->len = htons(skb->len); + uh->check = 0; + + skb->mark = ka->smark; + + switch (ka->family) { + case AF_INET: + err = nat_keepalive_send_ipv4(skb, ka); + break; +#if IS_ENABLED(CONFIG_IPV6) + case AF_INET6: + err = nat_keepalive_send_ipv6(skb, ka, uh); + break; +#endif + } + if (err) + kfree_skb(skb); +} + +struct nat_keepalive_work_ctx { + time64_t next_run; + time64_t now; +}; + +static int nat_keepalive_work_single(struct xfrm_state *x, int count, void *ptr) +{ + struct nat_keepalive_work_ctx *ctx = ptr; + bool send_keepalive = false; + struct nat_keepalive ka; + time64_t next_run; + u32 interval; + int delta; + + interval = x->nat_keepalive_interval; + if (!interval) + return 0; + + spin_lock(&x->lock); + + delta = (int)(ctx->now - x->lastused); + if (delta < interval) { + x->nat_keepalive_expiration = ctx->now + interval - delta; + next_run = x->nat_keepalive_expiration; + } else if (x->nat_keepalive_expiration > ctx->now) { + next_run = x->nat_keepalive_expiration; + } else { + next_run = ctx->now + interval; + nat_keepalive_init(&ka, x); + send_keepalive = true; + } + + spin_unlock(&x->lock); + + if (send_keepalive) + nat_keepalive_send(&ka); + + if (!ctx->next_run || next_run < ctx->next_run) + ctx->next_run = next_run; + return 0; +} + +static void nat_keepalive_work(struct work_struct *work) +{ + struct nat_keepalive_work_ctx ctx; + struct xfrm_state_walk walk; + struct net *net; + + ctx.next_run = 0; + ctx.now = ktime_get_real_seconds(); + + net = container_of(work, struct net, xfrm.nat_keepalive_work.work); + xfrm_state_walk_init(&walk, IPPROTO_ESP, NULL); + xfrm_state_walk(net, &walk, nat_keepalive_work_single, &ctx); + xfrm_state_walk_done(&walk, net); + if (ctx.next_run) + schedule_delayed_work(&net->xfrm.nat_keepalive_work, + (ctx.next_run - ctx.now) * HZ); +} + +static int nat_keepalive_sk_init(struct sock * __percpu *socks, + unsigned short family) +{ + struct sock *sk; + int err, i; + + for_each_possible_cpu(i) { + err = inet_ctl_sock_create(&sk, family, SOCK_RAW, IPPROTO_UDP, + &init_net); + if (err < 0) + goto err; + + *per_cpu_ptr(socks, i) = sk; + } + + return 0; +err: + for_each_possible_cpu(i) + inet_ctl_sock_destroy(*per_cpu_ptr(socks, i)); + return err; +} + +static void nat_keepalive_sk_fini(struct sock * __percpu *socks) +{ + int i; + + for_each_possible_cpu(i) + inet_ctl_sock_destroy(*per_cpu_ptr(socks, i)); +} + +void xfrm_nat_keepalive_state_updated(struct xfrm_state *x) +{ + struct net *net; + + if (!x->nat_keepalive_interval) + return; + + net = xs_net(x); + schedule_delayed_work(&net->xfrm.nat_keepalive_work, 0); +} + +int __net_init xfrm_nat_keepalive_net_init(struct net *net) +{ + INIT_DELAYED_WORK(&net->xfrm.nat_keepalive_work, nat_keepalive_work); + return 0; +} + +int xfrm_nat_keepalive_net_fini(struct net *net) +{ + cancel_delayed_work_sync(&net->xfrm.nat_keepalive_work); + return 0; +} + +int xfrm_nat_keepalive_init(unsigned short family) +{ + int err = -EAFNOSUPPORT; + + switch (family) { + case AF_INET: + err = nat_keepalive_sk_init(&nat_keepalive_sk_ipv4, PF_INET); + break; +#if IS_ENABLED(CONFIG_IPV6) + case AF_INET6: + err = nat_keepalive_sk_init(&nat_keepalive_sk_ipv6, PF_INET6); + break; +#endif + } + + if (err) + pr_err("xfrm nat keepalive init: failed to init err:%d\n", err); + return err; +} +EXPORT_SYMBOL_GPL(xfrm_nat_keepalive_init); + +void xfrm_nat_keepalive_fini(unsigned short family) +{ + switch (family) { + case AF_INET: + nat_keepalive_sk_fini(&nat_keepalive_sk_ipv4); + break; +#if IS_ENABLED(CONFIG_IPV6) + case AF_INET6: + nat_keepalive_sk_fini(&nat_keepalive_sk_ipv6); + break; +#endif + } +} +EXPORT_SYMBOL_GPL(xfrm_nat_keepalive_fini); diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index 475b904fe68b..6603d3bd171f 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -4289,8 +4289,14 @@ static int __net_init xfrm_net_init(struct net *net) if (rv < 0) goto out_sysctl; + rv = xfrm_nat_keepalive_net_init(net); + if (rv < 0) + goto out_nat_keepalive; + return 0; +out_nat_keepalive: + xfrm_sysctl_fini(net); out_sysctl: xfrm_policy_fini(net); out_policy: @@ -4303,6 +4309,7 @@ out_statistics: static void __net_exit xfrm_net_exit(struct net *net) { + xfrm_nat_keepalive_net_fini(net); xfrm_sysctl_fini(net); xfrm_policy_fini(net); xfrm_state_fini(net); @@ -4364,6 +4371,7 @@ void __init xfrm_init(void) #endif register_xfrm_state_bpf(); + xfrm_nat_keepalive_init(AF_INET); } #ifdef CONFIG_AUDITSYSCALL diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c index 649bb739df0d..abadc857cd45 100644 --- a/net/xfrm/xfrm_state.c +++ b/net/xfrm/xfrm_state.c @@ -715,6 +715,7 @@ int __xfrm_state_delete(struct xfrm_state *x) if (x->id.spi) hlist_del_rcu(&x->byspi); net->xfrm.state_num--; + xfrm_nat_keepalive_state_updated(x); spin_unlock(&net->xfrm.xfrm_state_lock); if (x->encap_sk) @@ -1453,6 +1454,7 @@ static void __xfrm_state_insert(struct xfrm_state *x) net->xfrm.state_num++; xfrm_hash_grow_check(net, x->bydst.next != NULL); + xfrm_nat_keepalive_state_updated(x); } /* net->xfrm.xfrm_state_lock is held */ @@ -2871,6 +2873,21 @@ int __xfrm_init_state(struct xfrm_state *x, bool init_replay, bool offload, goto error; } + if (x->nat_keepalive_interval) { + if (x->dir != XFRM_SA_DIR_OUT) { + NL_SET_ERR_MSG(extack, "NAT keepalive is only supported for outbound SAs"); + err = -EINVAL; + goto error; + } + + if (!x->encap || x->encap->encap_type != UDP_ENCAP_ESPINUDP) { + NL_SET_ERR_MSG(extack, + "NAT keepalive is only supported for UDP encapsulation"); + err = -EINVAL; + goto error; + } + } + error: return err; } diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index e83c687bd64e..a552cfa623ea 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -833,6 +833,10 @@ static struct xfrm_state *xfrm_state_construct(struct net *net, if (attrs[XFRMA_SA_DIR]) x->dir = nla_get_u8(attrs[XFRMA_SA_DIR]); + if (attrs[XFRMA_NAT_KEEPALIVE_INTERVAL]) + x->nat_keepalive_interval = + nla_get_u32(attrs[XFRMA_NAT_KEEPALIVE_INTERVAL]); + err = __xfrm_init_state(x, false, attrs[XFRMA_OFFLOAD_DEV], extack); if (err) goto error; @@ -1288,6 +1292,13 @@ static int copy_to_user_state_extra(struct xfrm_state *x, } if (x->dir) ret = nla_put_u8(skb, XFRMA_SA_DIR, x->dir); + + if (x->nat_keepalive_interval) { + ret = nla_put_u32(skb, XFRMA_NAT_KEEPALIVE_INTERVAL, + x->nat_keepalive_interval); + if (ret) + goto out; + } out: return ret; } @@ -3165,6 +3176,7 @@ const struct nla_policy xfrma_policy[XFRMA_MAX+1] = { [XFRMA_IF_ID] = { .type = NLA_U32 }, [XFRMA_MTIMER_THRESH] = { .type = NLA_U32 }, [XFRMA_SA_DIR] = NLA_POLICY_RANGE(NLA_U8, XFRM_SA_DIR_IN, XFRM_SA_DIR_OUT), + [XFRMA_NAT_KEEPALIVE_INTERVAL] = { .type = NLA_U32 }, }; EXPORT_SYMBOL_GPL(xfrma_policy); @@ -3474,6 +3486,9 @@ static inline unsigned int xfrm_sa_len(struct xfrm_state *x) if (x->dir) l += nla_total_size(sizeof(x->dir)); + if (x->nat_keepalive_interval) + l += nla_total_size(sizeof(x->nat_keepalive_interval)); + return l; }