1 files changed, 570 insertions, 0 deletions

diff --git a/net/ipv6/ioam6_iptunnel.c b/net/ipv6/ioam6_iptunnel.c
new file mode 100644
index 000000000000..1fe7894f14dd
--- /dev/null
+++ b/net/ipv6/ioam6_iptunnel.c
@@ -0,0 +1,570 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  IPv6 IOAM Lightweight Tunnel implementation
+ *
+ *  Author:
+ *  Justin Iurman <justin.iurman@uliege.be>
+ */
+
+#include <linux/kernel.h>
+#include <linux/skbuff.h>
+#include <linux/net.h>
+#include <linux/in6.h>
+#include <linux/ioam6.h>
+#include <linux/ioam6_iptunnel.h>
+#include <net/dst.h>
+#include <net/sock.h>
+#include <net/lwtunnel.h>
+#include <net/ioam6.h>
+#include <net/netlink.h>
+#include <net/ipv6.h>
+#include <net/dst_cache.h>
+#include <net/ip6_route.h>
+#include <net/addrconf.h>
+
+#define IOAM6_MASK_SHORT_FIELDS 0xff100000
+#define IOAM6_MASK_WIDE_FIELDS 0xe00000
+
+struct ioam6_lwt_encap {
+	struct ipv6_hopopt_hdr eh;
+	u8 pad[2];			/* 2-octet padding for 4n-alignment */
+	struct ioam6_hdr ioamh;
+	struct ioam6_trace_hdr traceh;
+} __packed;
+
+struct ioam6_lwt_freq {
+	u32 k;
+	u32 n;
+};
+
+struct ioam6_lwt {
+	struct dst_entry null_dst;
+	struct dst_cache cache;
+	struct ioam6_lwt_freq freq;
+	atomic_t pkt_cnt;
+	u8 mode;
+	bool has_tunsrc;
+	struct in6_addr tunsrc;
+	struct in6_addr tundst;
+	struct ioam6_lwt_encap tuninfo;
+};
+
+static const struct netlink_range_validation freq_range = {
+	.min = IOAM6_IPTUNNEL_FREQ_MIN,
+	.max = IOAM6_IPTUNNEL_FREQ_MAX,
+};
+
+static struct ioam6_lwt *ioam6_lwt_state(struct lwtunnel_state *lwt)
+{
+	return (struct ioam6_lwt *)lwt->data;
+}
+
+static struct ioam6_lwt_encap *ioam6_lwt_info(struct lwtunnel_state *lwt)
+{
+	return &ioam6_lwt_state(lwt)->tuninfo;
+}
+
+static struct ioam6_trace_hdr *ioam6_lwt_trace(struct lwtunnel_state *lwt)
+{
+	return &(ioam6_lwt_state(lwt)->tuninfo.traceh);
+}
+
+static const struct nla_policy ioam6_iptunnel_policy[IOAM6_IPTUNNEL_MAX + 1] = {
+	[IOAM6_IPTUNNEL_FREQ_K] = NLA_POLICY_FULL_RANGE(NLA_U32, &freq_range),
+	[IOAM6_IPTUNNEL_FREQ_N] = NLA_POLICY_FULL_RANGE(NLA_U32, &freq_range),
+	[IOAM6_IPTUNNEL_MODE]	= NLA_POLICY_RANGE(NLA_U8,
+						   IOAM6_IPTUNNEL_MODE_MIN,
+						   IOAM6_IPTUNNEL_MODE_MAX),
+	[IOAM6_IPTUNNEL_SRC]	= NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
+	[IOAM6_IPTUNNEL_DST]	= NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
+	[IOAM6_IPTUNNEL_TRACE]	= NLA_POLICY_EXACT_LEN(
+					sizeof(struct ioam6_trace_hdr)),
+};
+
+static bool ioam6_validate_trace_hdr(struct ioam6_trace_hdr *trace)
+{
+	u32 fields;
+
+	if (!trace->type_be32 || !trace->remlen ||
+	    trace->remlen > IOAM6_TRACE_DATA_SIZE_MAX / 4 ||
+	    trace->type.bit12 | trace->type.bit13 | trace->type.bit14 |
+	    trace->type.bit15 | trace->type.bit16 | trace->type.bit17 |
+	    trace->type.bit18 | trace->type.bit19 | trace->type.bit20 |
+	    trace->type.bit21 | trace->type.bit23)
+		return false;
+
+	trace->nodelen = 0;
+	fields = be32_to_cpu(trace->type_be32);
+
+	trace->nodelen += hweight32(fields & IOAM6_MASK_SHORT_FIELDS)
+				* (sizeof(__be32) / 4);
+	trace->nodelen += hweight32(fields & IOAM6_MASK_WIDE_FIELDS)
+				* (sizeof(__be64) / 4);
+
+	return true;
+}
+
+static int ioam6_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[IOAM6_IPTUNNEL_MAX + 1];
+	struct ioam6_lwt_encap *tuninfo;
+	struct ioam6_trace_hdr *trace;
+	struct lwtunnel_state *lwt;
+	struct ioam6_lwt *ilwt;
+	int len_aligned, err;
+	u32 freq_k, freq_n;
+	u8 mode;
+
+	if (family != AF_INET6)
+		return -EINVAL;
+
+	err = nla_parse_nested(tb, IOAM6_IPTUNNEL_MAX, nla,
+			       ioam6_iptunnel_policy, extack);
+	if (err < 0)
+		return err;
+
+	if ((!tb[IOAM6_IPTUNNEL_FREQ_K] && tb[IOAM6_IPTUNNEL_FREQ_N]) ||
+	    (tb[IOAM6_IPTUNNEL_FREQ_K] && !tb[IOAM6_IPTUNNEL_FREQ_N])) {
+		NL_SET_ERR_MSG(extack, "freq: missing parameter");
+		return -EINVAL;
+	} else if (!tb[IOAM6_IPTUNNEL_FREQ_K] && !tb[IOAM6_IPTUNNEL_FREQ_N]) {
+		freq_k = IOAM6_IPTUNNEL_FREQ_MIN;
+		freq_n = IOAM6_IPTUNNEL_FREQ_MIN;
+	} else {
+		freq_k = nla_get_u32(tb[IOAM6_IPTUNNEL_FREQ_K]);
+		freq_n = nla_get_u32(tb[IOAM6_IPTUNNEL_FREQ_N]);
+
+		if (freq_k > freq_n) {
+			NL_SET_ERR_MSG(extack, "freq: k > n is forbidden");
+			return -EINVAL;
+		}
+	}
+
+	mode = nla_get_u8_default(tb[IOAM6_IPTUNNEL_MODE],
+				  IOAM6_IPTUNNEL_MODE_INLINE);
+
+	if (tb[IOAM6_IPTUNNEL_SRC] && mode == IOAM6_IPTUNNEL_MODE_INLINE) {
+		NL_SET_ERR_MSG(extack, "no tunnel src expected with this mode");
+		return -EINVAL;
+	}
+
+	if (!tb[IOAM6_IPTUNNEL_DST] && mode != IOAM6_IPTUNNEL_MODE_INLINE) {
+		NL_SET_ERR_MSG(extack, "this mode needs a tunnel destination");
+		return -EINVAL;
+	}
+
+	if (!tb[IOAM6_IPTUNNEL_TRACE]) {
+		NL_SET_ERR_MSG(extack, "missing trace");
+		return -EINVAL;
+	}
+
+	trace = nla_data(tb[IOAM6_IPTUNNEL_TRACE]);
+	if (!ioam6_validate_trace_hdr(trace)) {
+		NL_SET_ERR_MSG_ATTR(extack, tb[IOAM6_IPTUNNEL_TRACE],
+				    "invalid trace validation");
+		return -EINVAL;
+	}
+
+	len_aligned = ALIGN(trace->remlen * 4, 8);
+	lwt = lwtunnel_state_alloc(sizeof(*ilwt) + len_aligned);
+	if (!lwt)
+		return -ENOMEM;
+
+	ilwt = ioam6_lwt_state(lwt);
+	err = dst_cache_init(&ilwt->cache, GFP_ATOMIC);
+	if (err)
+		goto free_lwt;
+
+	/* This "fake" dst_entry will be stored in a dst_cache, which will call
+	 * dst_hold() and dst_release() on it. We must ensure that dst_destroy()
+	 * will never be called. For that, its initial refcount is 1 and +1 when
+	 * it is stored in the cache. Then, +1/-1 each time we read the cache
+	 * and release it. Long story short, we're fine.
+	 */
+	dst_init(&ilwt->null_dst, NULL, NULL, DST_OBSOLETE_NONE, DST_NOCOUNT);
+
+	atomic_set(&ilwt->pkt_cnt, 0);
+	ilwt->freq.k = freq_k;
+	ilwt->freq.n = freq_n;
+
+	ilwt->mode = mode;
+
+	if (!tb[IOAM6_IPTUNNEL_SRC]) {
+		ilwt->has_tunsrc = false;
+	} else {
+		ilwt->has_tunsrc = true;
+		ilwt->tunsrc = nla_get_in6_addr(tb[IOAM6_IPTUNNEL_SRC]);
+
+		if (ipv6_addr_any(&ilwt->tunsrc)) {
+			NL_SET_ERR_MSG_ATTR(extack, tb[IOAM6_IPTUNNEL_SRC],
+					    "invalid tunnel source address");
+			err = -EINVAL;
+			goto free_cache;
+		}
+	}
+
+	if (tb[IOAM6_IPTUNNEL_DST]) {
+		ilwt->tundst = nla_get_in6_addr(tb[IOAM6_IPTUNNEL_DST]);
+
+		if (ipv6_addr_any(&ilwt->tundst)) {
+			NL_SET_ERR_MSG_ATTR(extack, tb[IOAM6_IPTUNNEL_DST],
+					    "invalid tunnel dest address");
+			err = -EINVAL;
+			goto free_cache;
+		}
+	}
+
+	tuninfo = ioam6_lwt_info(lwt);
+	tuninfo->eh.hdrlen = ((sizeof(*tuninfo) + len_aligned) >> 3) - 1;
+	tuninfo->pad[0] = IPV6_TLV_PADN;
+	tuninfo->ioamh.type = IOAM6_TYPE_PREALLOC;
+	tuninfo->ioamh.opt_type = IPV6_TLV_IOAM;
+	tuninfo->ioamh.opt_len = sizeof(tuninfo->ioamh) - 2 + sizeof(*trace)
+					+ trace->remlen * 4;
+
+	memcpy(&tuninfo->traceh, trace, sizeof(*trace));
+
+	if (len_aligned - trace->remlen * 4) {
+		tuninfo->traceh.data[trace->remlen * 4] = IPV6_TLV_PADN;
+		tuninfo->traceh.data[trace->remlen * 4 + 1] = 2;
+	}
+
+	lwt->type = LWTUNNEL_ENCAP_IOAM6;
+	lwt->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
+
+	*ts = lwt;
+
+	return 0;
+free_cache:
+	dst_cache_destroy(&ilwt->cache);
+free_lwt:
+	kfree(lwt);
+	return err;
+}
+
+static int ioam6_do_fill(struct net *net, struct sk_buff *skb)
+{
+	struct ioam6_trace_hdr *trace;
+	struct ioam6_namespace *ns;
+
+	trace = (struct ioam6_trace_hdr *)(skb_transport_header(skb)
+					   + sizeof(struct ipv6_hopopt_hdr) + 2
+					   + sizeof(struct ioam6_hdr));
+
+	ns = ioam6_namespace(net, trace->namespace_id);
+	if (ns)
+		ioam6_fill_trace_data(skb, ns, trace, false);
+
+	return 0;
+}
+
+static int ioam6_do_inline(struct net *net, struct sk_buff *skb,
+			   struct ioam6_lwt_encap *tuninfo,
+			   struct dst_entry *cache_dst)
+{
+	struct ipv6hdr *oldhdr, *hdr;
+	int hdrlen, err;
+
+	hdrlen = (tuninfo->eh.hdrlen + 1) << 3;
+
+	err = skb_cow_head(skb, hdrlen + dst_dev_overhead(cache_dst, skb));
+	if (unlikely(err))
+		return err;
+
+	oldhdr = ipv6_hdr(skb);
+	skb_pull(skb, sizeof(*oldhdr));
+	skb_postpull_rcsum(skb, skb_network_header(skb), sizeof(*oldhdr));
+
+	skb_push(skb, sizeof(*oldhdr) + hdrlen);
+	skb_reset_network_header(skb);
+	skb_mac_header_rebuild(skb);
+
+	hdr = ipv6_hdr(skb);
+	memmove(hdr, oldhdr, sizeof(*oldhdr));
+	tuninfo->eh.nexthdr = hdr->nexthdr;
+
+	skb_set_transport_header(skb, sizeof(*hdr));
+	skb_postpush_rcsum(skb, hdr, sizeof(*hdr) + hdrlen);
+
+	memcpy(skb_transport_header(skb), (u8 *)tuninfo, hdrlen);
+
+	hdr->nexthdr = NEXTHDR_HOP;
+	hdr->payload_len = cpu_to_be16(skb->len - sizeof(*hdr));
+
+	return ioam6_do_fill(net, skb);
+}
+
+static int ioam6_do_encap(struct net *net, struct sk_buff *skb,
+			  struct ioam6_lwt_encap *tuninfo,
+			  bool has_tunsrc,
+			  struct in6_addr *tunsrc,
+			  struct in6_addr *tundst,
+			  struct dst_entry *cache_dst)
+{
+	struct dst_entry *dst = skb_dst(skb);
+	struct ipv6hdr *hdr, *inner_hdr;
+	int hdrlen, len, err;
+
+	hdrlen = (tuninfo->eh.hdrlen + 1) << 3;
+	len = sizeof(*hdr) + hdrlen;
+
+	err = skb_cow_head(skb, len + dst_dev_overhead(cache_dst, skb));
+	if (unlikely(err))
+		return err;
+
+	inner_hdr = ipv6_hdr(skb);
+
+	skb_push(skb, len);
+	skb_reset_network_header(skb);
+	skb_mac_header_rebuild(skb);
+	skb_set_transport_header(skb, sizeof(*hdr));
+
+	tuninfo->eh.nexthdr = NEXTHDR_IPV6;
+	memcpy(skb_transport_header(skb), (u8 *)tuninfo, hdrlen);
+
+	hdr = ipv6_hdr(skb);
+	memcpy(hdr, inner_hdr, sizeof(*hdr));
+
+	hdr->nexthdr = NEXTHDR_HOP;
+	hdr->payload_len = cpu_to_be16(skb->len - sizeof(*hdr));
+	hdr->daddr = *tundst;
+
+	if (has_tunsrc)
+		memcpy(&hdr->saddr, tunsrc, sizeof(*tunsrc));
+	else
+		ipv6_dev_get_saddr(net, dst_dev(dst), &hdr->daddr,
+				   IPV6_PREFER_SRC_PUBLIC, &hdr->saddr);
+
+	skb_postpush_rcsum(skb, hdr, len);
+
+	return ioam6_do_fill(net, skb);
+}
+
+static int ioam6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
+{
+	struct dst_entry *orig_dst = skb_dst(skb);
+	struct dst_entry *dst = NULL;
+	struct ioam6_lwt *ilwt;
+	int err = -EINVAL;
+	u32 pkt_cnt;
+
+	if (skb->protocol != htons(ETH_P_IPV6))
+		goto drop;
+
+	ilwt = ioam6_lwt_state(orig_dst->lwtstate);
+
+	/* Check for insertion frequency (i.e., "k over n" insertions) */
+	pkt_cnt = atomic_fetch_inc(&ilwt->pkt_cnt);
+	if (pkt_cnt % ilwt->freq.n >= ilwt->freq.k)
+		goto out;
+
+	local_bh_disable();
+	dst = dst_cache_get(&ilwt->cache);
+	local_bh_enable();
+
+	/* This is how we notify that the destination does not change after
+	 * transformation and that we need to use orig_dst instead of the cache
+	 */
+	if (dst == &ilwt->null_dst) {
+		dst_release(dst);
+
+		dst = orig_dst;
+		/* keep refcount balance: dst_release() is called at the end */
+		dst_hold(dst);
+	}
+
+	switch (ilwt->mode) {
+	case IOAM6_IPTUNNEL_MODE_INLINE:
+do_inline:
+		/* Direct insertion - if there is no Hop-by-Hop yet */
+		if (ipv6_hdr(skb)->nexthdr == NEXTHDR_HOP)
+			goto out;
+
+		err = ioam6_do_inline(net, skb, &ilwt->tuninfo, dst);
+		if (unlikely(err))
+			goto drop;
+
+		break;
+	case IOAM6_IPTUNNEL_MODE_ENCAP:
+do_encap:
+		/* Encapsulation (ip6ip6) */
+		err = ioam6_do_encap(net, skb, &ilwt->tuninfo,
+				     ilwt->has_tunsrc, &ilwt->tunsrc,
+				     &ilwt->tundst, dst);
+		if (unlikely(err))
+			goto drop;
+
+		break;
+	case IOAM6_IPTUNNEL_MODE_AUTO:
+		/* Automatic (RFC8200 compliant):
+		 *  - local packets -> INLINE mode
+		 *  - in-transit packets -> ENCAP mode
+		 */
+		if (!skb->dev)
+			goto do_inline;
+
+		goto do_encap;
+	default:
+		goto drop;
+	}
+
+	if (unlikely(!dst)) {
+		struct ipv6hdr *hdr = ipv6_hdr(skb);
+		struct flowi6 fl6;
+
+		memset(&fl6, 0, sizeof(fl6));
+		fl6.daddr = hdr->daddr;
+		fl6.saddr = hdr->saddr;
+		fl6.flowlabel = ip6_flowinfo(hdr);
+		fl6.flowi6_mark = skb->mark;
+		fl6.flowi6_proto = hdr->nexthdr;
+
+		dst = ip6_route_output(net, NULL, &fl6);
+		if (dst->error) {
+			err = dst->error;
+			goto drop;
+		}
+
+		/* If the destination is the same after transformation (which is
+		 * a valid use case for IOAM), then we don't want to add it to
+		 * the cache in order to avoid a reference loop. Instead, we add
+		 * our fake dst_entry to the cache as a way to detect this case.
+		 * Otherwise, we add the resolved destination to the cache.
+		 */
+		local_bh_disable();
+		if (orig_dst->lwtstate == dst->lwtstate)
+			dst_cache_set_ip6(&ilwt->cache,
+					  &ilwt->null_dst, &fl6.saddr);
+		else
+			dst_cache_set_ip6(&ilwt->cache, dst, &fl6.saddr);
+		local_bh_enable();
+
+		err = skb_cow_head(skb, LL_RESERVED_SPACE(dst_dev(dst)));
+		if (unlikely(err))
+			goto drop;
+	}
+
+	/* avoid lwtunnel_output() reentry loop when destination is the same
+	 * after transformation (e.g., with the inline mode)
+	 */
+	if (orig_dst->lwtstate != dst->lwtstate) {
+		skb_dst_drop(skb);
+		skb_dst_set(skb, dst);
+		return dst_output(net, sk, skb);
+	}
+out:
+	dst_release(dst);
+	return orig_dst->lwtstate->orig_output(net, sk, skb);
+drop:
+	dst_release(dst);
+	kfree_skb(skb);
+	return err;
+}
+
+static void ioam6_destroy_state(struct lwtunnel_state *lwt)
+{
+	/* Since the refcount of per-cpu dst_entry caches will never be 0 (see
+	 * why above) when our "fake" dst_entry is used, it is not necessary to
+	 * remove them before calling dst_cache_destroy()
+	 */
+	dst_cache_destroy(&ioam6_lwt_state(lwt)->cache);
+}
+
+static int ioam6_fill_encap_info(struct sk_buff *skb,
+				 struct lwtunnel_state *lwtstate)
+{
+	struct ioam6_lwt *ilwt = ioam6_lwt_state(lwtstate);
+	int err;
+
+	err = nla_put_u32(skb, IOAM6_IPTUNNEL_FREQ_K, ilwt->freq.k);
+	if (err)
+		goto ret;
+
+	err = nla_put_u32(skb, IOAM6_IPTUNNEL_FREQ_N, ilwt->freq.n);
+	if (err)
+		goto ret;
+
+	err = nla_put_u8(skb, IOAM6_IPTUNNEL_MODE, ilwt->mode);
+	if (err)
+		goto ret;
+
+	if (ilwt->mode != IOAM6_IPTUNNEL_MODE_INLINE) {
+		if (ilwt->has_tunsrc) {
+			err = nla_put_in6_addr(skb, IOAM6_IPTUNNEL_SRC,
+					       &ilwt->tunsrc);
+			if (err)
+				goto ret;
+		}
+
+		err = nla_put_in6_addr(skb, IOAM6_IPTUNNEL_DST, &ilwt->tundst);
+		if (err)
+			goto ret;
+	}
+
+	err = nla_put(skb, IOAM6_IPTUNNEL_TRACE, sizeof(ilwt->tuninfo.traceh),
+		      &ilwt->tuninfo.traceh);
+ret:
+	return err;
+}
+
+static int ioam6_encap_nlsize(struct lwtunnel_state *lwtstate)
+{
+	struct ioam6_lwt *ilwt = ioam6_lwt_state(lwtstate);
+	int nlsize;
+
+	nlsize = nla_total_size(sizeof(ilwt->freq.k)) +
+		  nla_total_size(sizeof(ilwt->freq.n)) +
+		  nla_total_size(sizeof(ilwt->mode)) +
+		  nla_total_size(sizeof(ilwt->tuninfo.traceh));
+
+	if (ilwt->mode != IOAM6_IPTUNNEL_MODE_INLINE) {
+		if (ilwt->has_tunsrc)
+			nlsize += nla_total_size(sizeof(ilwt->tunsrc));
+
+		nlsize += nla_total_size(sizeof(ilwt->tundst));
+	}
+
+	return nlsize;
+}
+
+static int ioam6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
+{
+	struct ioam6_trace_hdr *trace_a = ioam6_lwt_trace(a);
+	struct ioam6_trace_hdr *trace_b = ioam6_lwt_trace(b);
+	struct ioam6_lwt *ilwt_a = ioam6_lwt_state(a);
+	struct ioam6_lwt *ilwt_b = ioam6_lwt_state(b);
+
+	return (ilwt_a->freq.k != ilwt_b->freq.k ||
+		ilwt_a->freq.n != ilwt_b->freq.n ||
+		ilwt_a->mode != ilwt_b->mode ||
+		ilwt_a->has_tunsrc != ilwt_b->has_tunsrc ||
+		(ilwt_a->mode != IOAM6_IPTUNNEL_MODE_INLINE &&
+		 !ipv6_addr_equal(&ilwt_a->tundst, &ilwt_b->tundst)) ||
+		(ilwt_a->mode != IOAM6_IPTUNNEL_MODE_INLINE &&
+		 ilwt_a->has_tunsrc &&
+		 !ipv6_addr_equal(&ilwt_a->tunsrc, &ilwt_b->tunsrc)) ||
+		trace_a->namespace_id != trace_b->namespace_id);
+}
+
+static const struct lwtunnel_encap_ops ioam6_iptun_ops = {
+	.build_state		= ioam6_build_state,
+	.destroy_state		= ioam6_destroy_state,
+	.output			= ioam6_output,
+	.fill_encap		= ioam6_fill_encap_info,
+	.get_encap_size		= ioam6_encap_nlsize,
+	.cmp_encap		= ioam6_encap_cmp,
+	.owner			= THIS_MODULE,
+};
+
+int __init ioam6_iptunnel_init(void)
+{
+	return lwtunnel_encap_add_ops(&ioam6_iptun_ops, LWTUNNEL_ENCAP_IOAM6);
+}
+
+void ioam6_iptunnel_exit(void)
+{
+	lwtunnel_encap_del_ops(&ioam6_iptun_ops, LWTUNNEL_ENCAP_IOAM6);
+}