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Message-ID: <20240520214255.2590923-10-chopps@chopps.org>
Date: Mon, 20 May 2024 17:42:47 -0400
From: Christian Hopps <chopps@...pps.org>
To: devel@...ux-ipsec.org
Cc: Steffen Klassert <steffen.klassert@...unet.com>,
netdev@...r.kernel.org,
Christian Hopps <chopps@...pps.org>,
Christian Hopps <chopps@...n.net>
Subject: [PATCH ipsec-next v2 09/17] xfrm: iptfs: add user packet (tunnel ingress) handling
From: Christian Hopps <chopps@...n.net>
Add tunnel packet output functionality. This is code handles
the ingress to the tunnel.
Signed-off-by: Christian Hopps <chopps@...n.net>
---
net/xfrm/xfrm_iptfs.c | 519 +++++++++++++++++++++++++++++++++++++++++-
1 file changed, 516 insertions(+), 3 deletions(-)
diff --git a/net/xfrm/xfrm_iptfs.c b/net/xfrm/xfrm_iptfs.c
index e7b5546e1f6a..561483fc83f9 100644
--- a/net/xfrm/xfrm_iptfs.c
+++ b/net/xfrm/xfrm_iptfs.c
@@ -19,8 +19,13 @@
#include "xfrm_inout.h"
+#define NSECS_IN_USEC 1000
+
+#define IPTFS_HRTIMER_MODE HRTIMER_MODE_REL_SOFT
+
struct xfrm_iptfs_config {
u32 pkt_size; /* outer_packet_size or 0 */
+ u32 max_queue_size; /* octets */
};
struct xfrm_iptfs_data {
@@ -28,9 +33,495 @@ struct xfrm_iptfs_data {
/* Ingress User Input */
struct xfrm_state *x; /* owning state */
+ struct sk_buff_head queue; /* output queue */
+ u32 queue_size; /* octets */
+ u32 ecn_queue_size; /* octets above which ECN mark */
+ u64 init_delay_ns; /* nanoseconds */
+ struct hrtimer iptfs_timer; /* output timer */
+ time64_t iptfs_settime; /* time timer was set */
u32 payload_mtu; /* max payload size */
};
+static u32 iptfs_get_inner_mtu(struct xfrm_state *x, int outer_mtu);
+static enum hrtimer_restart iptfs_delay_timer(struct hrtimer *me);
+
+/* ================================= */
+/* IPTFS Sending (ingress) Functions */
+/* ================================= */
+
+/* ------------------------- */
+/* Enqueue to send functions */
+/* ------------------------- */
+
+/**
+ * iptfs_enqueue() - enqueue packet if ok to send.
+ * @xtfs: xtfs state
+ * @skb: the packet
+ *
+ * Return: true if packet enqueued.
+ */
+static bool iptfs_enqueue(struct xfrm_iptfs_data *xtfs, struct sk_buff *skb)
+{
+ u64 newsz = xtfs->queue_size + skb->len;
+ struct iphdr *iph;
+
+ assert_spin_locked(&xtfs->x->lock);
+
+ if (newsz > xtfs->cfg.max_queue_size)
+ return false;
+
+ /* Set ECN CE if we are above our ECN queue threshold */
+ if (newsz > xtfs->ecn_queue_size) {
+ iph = ip_hdr(skb);
+ if (iph->version == 4)
+ IP_ECN_set_ce(iph);
+ else if (iph->version == 6)
+ IP6_ECN_set_ce(skb, ipv6_hdr(skb));
+ }
+
+ __skb_queue_tail(&xtfs->queue, skb);
+ xtfs->queue_size += skb->len;
+ return true;
+}
+
+static int iptfs_get_cur_pmtu(struct xfrm_state *x,
+ struct xfrm_iptfs_data *xtfs, struct sk_buff *skb)
+{
+ struct xfrm_dst *xdst = (struct xfrm_dst *)skb_dst(skb);
+ u32 payload_mtu = xtfs->payload_mtu;
+ u32 pmtu = iptfs_get_inner_mtu(x, xdst->child_mtu_cached);
+
+ if (payload_mtu && payload_mtu < pmtu)
+ pmtu = payload_mtu;
+
+ return pmtu;
+}
+
+static int iptfs_is_too_big(struct sock *sk, struct sk_buff *skb, u32 pmtu)
+{
+ if (skb->len <= pmtu)
+ return 0;
+
+ /* We only send ICMP too big if the user has configured us as
+ * dont-fragment.
+ */
+ XFRM_INC_STATS(dev_net(skb->dev), LINUX_MIB_XFRMOUTERROR);
+
+ if (sk) {
+ xfrm_local_error(skb, pmtu);
+ } else if (ip_hdr(skb)->version == 4) {
+ icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
+ htonl(pmtu));
+ } else {
+ WARN_ON_ONCE(ip_hdr(skb)->version != 6);
+ icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, pmtu);
+ }
+ return 1;
+}
+
+/* IPv4/IPv6 packet ingress to IPTFS tunnel, arrange to send in IPTFS payload
+ * (i.e., aggregating or fragmenting as appropriate).
+ * This is set in dst->output for an SA.
+ */
+static int iptfs_output_collect(struct net *net, struct sock *sk,
+ struct sk_buff *skb)
+{
+ struct dst_entry *dst = skb_dst(skb);
+ struct xfrm_state *x = dst->xfrm;
+ struct xfrm_iptfs_data *xtfs = x->mode_data;
+ struct sk_buff *segs, *nskb;
+ u32 pmtu = 0;
+ bool ok = true;
+ bool was_gso;
+
+ /* We have hooked into dst_entry->output which means we have skipped the
+ * protocol specific netfilter (see xfrm4_output, xfrm6_output).
+ * when our timer runs we will end up calling xfrm_output directly on
+ * the encapsulated traffic.
+ *
+ * For both cases this is the NF_INET_POST_ROUTING hook which allows
+ * changing the skb->dst entry which then may not be xfrm based anymore
+ * in which case a REROUTED flag is set. and dst_output is called.
+ *
+ * For IPv6 we are also skipping fragmentation handling for local
+ * sockets, which may or may not be good depending on our tunnel DF
+ * setting. Normally with fragmentation supported we want to skip this
+ * fragmentation.
+ */
+
+ BUG_ON(!xtfs);
+
+ pmtu = iptfs_get_cur_pmtu(x, xtfs, skb);
+
+ /* Break apart GSO skbs. If the queue is nearing full then we want the
+ * accounting and queuing to be based on the individual packets not on the
+ * aggregate GSO buffer.
+ */
+ was_gso = skb_is_gso(skb);
+ if (!was_gso) {
+ segs = skb;
+ } else {
+ segs = skb_gso_segment(skb, 0);
+ if (IS_ERR_OR_NULL(segs)) {
+ XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
+ kfree_skb(skb);
+ return PTR_ERR(segs);
+ }
+ consume_skb(skb);
+ skb = NULL;
+ }
+
+ /* We can be running on multiple cores and from the network softirq or
+ * from user context depending on where the packet is coming from.
+ */
+ spin_lock_bh(&x->lock);
+
+ skb_list_walk_safe(segs, skb, nskb)
+ {
+ skb_mark_not_on_list(skb);
+
+ /* Once we drop due to no queue space we continue to drop the
+ * rest of the packets from that GRO.
+ */
+ if (!ok) {
+nospace:
+ XFRM_INC_STATS(dev_net(skb->dev),
+ LINUX_MIB_XFRMOUTNOQSPACE);
+ kfree_skb_reason(skb, SKB_DROP_REASON_FULL_RING);
+ continue;
+ }
+
+ /* Fragmenting handled in following commits. */
+ if (iptfs_is_too_big(sk, skb, pmtu)) {
+ kfree_skb_reason(skb, SKB_DROP_REASON_PKT_TOO_BIG);
+ continue;
+ }
+
+ /* Enqueue to send in tunnel */
+ ok = iptfs_enqueue(xtfs, skb);
+ if (!ok)
+ goto nospace;
+ }
+
+ /* Start a delay timer if we don't have one yet */
+ if (!hrtimer_is_queued(&xtfs->iptfs_timer)) {
+ hrtimer_start(&xtfs->iptfs_timer, xtfs->init_delay_ns,
+ IPTFS_HRTIMER_MODE);
+ xtfs->iptfs_settime = ktime_get_raw_fast_ns();
+ }
+
+ spin_unlock_bh(&x->lock);
+ return 0;
+}
+
+/* -------------------------- */
+/* Dequeue and send functions */
+/* -------------------------- */
+
+static void iptfs_output_prepare_skb(struct sk_buff *skb, u32 blkoff)
+{
+ struct ip_iptfs_hdr *h;
+ size_t hsz = sizeof(*h);
+
+ /* now reset values to be pointing at the rest of the packets */
+ h = skb_push(skb, hsz);
+ memset(h, 0, hsz);
+ if (blkoff)
+ h->block_offset = htons(blkoff);
+
+ /* network_header current points at the inner IP packet
+ * move it to the iptfs header
+ */
+ skb->transport_header = skb->network_header;
+ skb->network_header -= hsz;
+
+ IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
+}
+
+static struct sk_buff **iptfs_rehome_fraglist(struct sk_buff **nextp,
+ struct sk_buff *child)
+{
+ u32 fllen = 0;
+
+ /* It might be possible to account for a frag list in addition to page
+ * fragment if it's a valid state to be in. The page fragments size
+ * should be kept as data_len so only the frag_list size is removed,
+ * this must be done above as well.
+ */
+ BUG_ON(skb_shinfo(child)->nr_frags);
+ *nextp = skb_shinfo(child)->frag_list;
+ while (*nextp) {
+ fllen += (*nextp)->len;
+ nextp = &(*nextp)->next;
+ }
+ skb_frag_list_init(child);
+ BUG_ON(fllen > child->data_len);
+ child->len -= fllen;
+ child->data_len -= fllen;
+
+ return nextp;
+}
+
+static void iptfs_output_queued(struct xfrm_state *x, struct sk_buff_head *list)
+{
+ struct xfrm_iptfs_data *xtfs = x->mode_data;
+ struct sk_buff *skb, *skb2, **nextp;
+ struct skb_shared_info *shi;
+
+ while ((skb = __skb_dequeue(list))) {
+ u32 mtu = iptfs_get_cur_pmtu(x, xtfs, skb);
+ int remaining;
+
+ /* protocol comes to us cleared sometimes */
+ skb->protocol = x->outer_mode.family == AF_INET ?
+ htons(ETH_P_IP) :
+ htons(ETH_P_IPV6);
+
+ if (skb->len > mtu) {
+ /* We handle this case before enqueueing so we are only
+ * here b/c MTU changed after we enqueued before we
+ * dequeued, just drop these.
+ */
+ XFRM_INC_STATS(dev_net(skb->dev),
+ LINUX_MIB_XFRMOUTERROR);
+
+ kfree_skb_reason(skb, SKB_DROP_REASON_PKT_TOO_BIG);
+ continue;
+ }
+
+ /* If we don't have a cksum in the packet we need to add one
+ * before encapsulation.
+ */
+ if (skb->ip_summed == CHECKSUM_PARTIAL) {
+ if (skb_checksum_help(skb)) {
+ XFRM_INC_STATS(dev_net(skb_dst(skb)->dev),
+ LINUX_MIB_XFRMOUTERROR);
+ kfree_skb(skb);
+ continue;
+ }
+ }
+
+ /* Convert first inner packet into an outer IPTFS packet */
+ iptfs_output_prepare_skb(skb, 0);
+
+ /* The space remaining to send more inner packet data is `mtu` -
+ * (skb->len - sizeof iptfs header). This is b/c the `mtu` value
+ * has the basic IPTFS header len accounted for, and we added
+ * that header to the skb so it is a part of skb->len, thus we
+ * subtract it from the skb length.
+ */
+ remaining = mtu - (skb->len - sizeof(struct ip_iptfs_hdr));
+
+ /* Re-home (un-nest) nested fragment lists. We need to do this
+ * b/c we will simply be appending any following aggregated
+ * inner packets to the frag list.
+ */
+ shi = skb_shinfo(skb);
+ nextp = &shi->frag_list;
+ while (*nextp) {
+ if (skb_has_frag_list(*nextp))
+ nextp = iptfs_rehome_fraglist(&(*nextp)->next,
+ *nextp);
+ else
+ nextp = &(*nextp)->next;
+ }
+
+ /* See if we have enough space to simply append.
+ *
+ * NOTE: Maybe do not append if we will be mis-aligned,
+ * SW-based endpoints will probably have to copy in this
+ * case.
+ */
+ while ((skb2 = skb_peek(list))) {
+ if (skb2->len > remaining)
+ break;
+
+ __skb_unlink(skb2, list);
+
+ /* If we don't have a cksum in the packet we need to add
+ * one before encapsulation.
+ */
+ if (skb2->ip_summed == CHECKSUM_PARTIAL) {
+ if (skb_checksum_help(skb2)) {
+ XFRM_INC_STATS(
+ dev_net(skb_dst(skb2)->dev),
+ LINUX_MIB_XFRMOUTERROR);
+ kfree_skb(skb2);
+ continue;
+ }
+ }
+
+ /* Do accounting */
+ skb->data_len += skb2->len;
+ skb->len += skb2->len;
+ remaining -= skb2->len;
+
+ /* Append to the frag_list */
+ *nextp = skb2;
+ nextp = &skb2->next;
+ BUG_ON(*nextp);
+ if (skb_has_frag_list(skb2))
+ nextp = iptfs_rehome_fraglist(nextp, skb2);
+ skb->truesize += skb2->truesize;
+ }
+
+ xfrm_output(NULL, skb);
+ }
+}
+
+static enum hrtimer_restart iptfs_delay_timer(struct hrtimer *me)
+{
+ struct sk_buff_head list;
+ struct xfrm_iptfs_data *xtfs;
+ struct xfrm_state *x;
+ time64_t settime;
+
+ xtfs = container_of(me, typeof(*xtfs), iptfs_timer);
+ x = xtfs->x;
+
+ /* Process all the queued packets
+ *
+ * softirq execution order: timer > tasklet > hrtimer
+ *
+ * Network rx will have run before us giving one last chance to queue
+ * ingress packets for us to process and transmit.
+ */
+
+ spin_lock(&x->lock);
+ __skb_queue_head_init(&list);
+ skb_queue_splice_init(&xtfs->queue, &list);
+ xtfs->queue_size = 0;
+ settime = xtfs->iptfs_settime;
+ spin_unlock(&x->lock);
+
+ /* After the above unlock, packets can begin queuing again, and the
+ * timer can be set again, from another CPU either in softirq or user
+ * context (not from this one since we are running at softirq level
+ * already).
+ */
+
+ iptfs_output_queued(x, &list);
+
+ return HRTIMER_NORESTART;
+}
+
+/**
+ * iptfs_encap_add_ipv4() - add outer encaps
+ * @x: xfrm state
+ * @skb: the packet
+ *
+ * This was originally taken from xfrm4_tunnel_encap_add. The reason for the
+ * copy is that IP-TFS/AGGFRAG can have different functionality for how to set
+ * the TOS/DSCP bits. Sets the protocol to a different value and doesn't do
+ * anything with inner headers as they aren't pointing into a normal IP
+ * singleton inner packet.
+ */
+static int iptfs_encap_add_ipv4(struct xfrm_state *x, struct sk_buff *skb)
+{
+ struct dst_entry *dst = skb_dst(skb);
+ struct iphdr *top_iph;
+
+ skb_reset_inner_network_header(skb);
+ skb_reset_inner_transport_header(skb);
+
+ skb_set_network_header(skb,
+ -(x->props.header_len - x->props.enc_hdr_len));
+ skb->mac_header =
+ skb->network_header + offsetof(struct iphdr, protocol);
+ skb->transport_header = skb->network_header + sizeof(*top_iph);
+
+ top_iph = ip_hdr(skb);
+ top_iph->ihl = 5;
+ top_iph->version = 4;
+ top_iph->protocol = IPPROTO_AGGFRAG;
+
+ /* As we have 0, fractional, 1 or N inner packets there's no obviously
+ * correct DSCP mapping to inherit. ECN should be cleared per RFC9347
+ * 3.1.
+ */
+ top_iph->tos = 0;
+
+ top_iph->frag_off = htons(IP_DF);
+ top_iph->ttl = ip4_dst_hoplimit(xfrm_dst_child(dst));
+ top_iph->saddr = x->props.saddr.a4;
+ top_iph->daddr = x->id.daddr.a4;
+ ip_select_ident(dev_net(dst->dev), skb, NULL);
+
+ return 0;
+}
+
+/**
+ * iptfs_encap_add_ipv6() - add outer encaps
+ * @x: xfrm state
+ * @skb: the packet
+ *
+ * This was originally taken from xfrm6_tunnel_encap_add. The reason for the
+ * copy is that IP-TFS/AGGFRAG can have different functionality for how to set
+ * the flow label and TOS/DSCP bits. It also sets the protocol to a different
+ * value and doesn't do anything with inner headers as they aren't pointing into
+ * a normal IP singleton inner packet.
+ */
+static int iptfs_encap_add_ipv6(struct xfrm_state *x, struct sk_buff *skb)
+{
+ struct dst_entry *dst = skb_dst(skb);
+ struct ipv6hdr *top_iph;
+ int dsfield;
+
+ skb_reset_inner_network_header(skb);
+ skb_reset_inner_transport_header(skb);
+
+ skb_set_network_header(skb,
+ -x->props.header_len + x->props.enc_hdr_len);
+ skb->mac_header =
+ skb->network_header + offsetof(struct ipv6hdr, nexthdr);
+ skb->transport_header = skb->network_header + sizeof(*top_iph);
+
+ top_iph = ipv6_hdr(skb);
+ top_iph->version = 6;
+ top_iph->priority = 0;
+ memset(top_iph->flow_lbl, 0, sizeof(top_iph->flow_lbl));
+ top_iph->nexthdr = IPPROTO_AGGFRAG;
+
+ /* As we have 0, fractional, 1 or N inner packets there's no obviously
+ * correct DSCP mapping to inherit. ECN should be cleared per RFC9347
+ * 3.1.
+ */
+ dsfield = 0;
+ ipv6_change_dsfield(top_iph, 0, dsfield);
+
+ top_iph->hop_limit = ip6_dst_hoplimit(xfrm_dst_child(dst));
+ top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
+ top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
+
+ return 0;
+}
+
+/**
+ * iptfs_prepare_output() - prepare the skb for output
+ * @x: xfrm state
+ * @skb: the packet
+ *
+ * Return: Error value, if 0 then skb values should be as follows:
+ * - transport_header should point at ESP header
+ * - network_header should point at Outer IP header
+ * - mac_header should point at protocol/nexthdr of the outer IP
+ */
+static int iptfs_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
+{
+ if (x->outer_mode.family == AF_INET)
+ return iptfs_encap_add_ipv4(x, skb);
+ if (x->outer_mode.family == AF_INET6) {
+#if IS_ENABLED(CONFIG_IPV6)
+ return iptfs_encap_add_ipv6(x, skb);
+#else
+ WARN_ON_ONCE(1);
+ return -EAFNOSUPPORT;
+#endif
+ }
+ WARN_ON_ONCE(1);
+ return -EOPNOTSUPP;
+}
+
/* ========================== */
/* State Management Functions */
/* ========================== */
@@ -66,6 +557,9 @@ static int iptfs_user_init(struct net *net, struct xfrm_state *x,
struct xfrm_iptfs_config *xc;
xc = &xtfs->cfg;
+ xc->max_queue_size = net->xfrm.sysctl_iptfs_max_qsize;
+ xtfs->init_delay_ns =
+ (u64)net->xfrm.sysctl_iptfs_init_delay * NSECS_IN_USEC;
if (attrs[XFRMA_IPTFS_PKT_SIZE]) {
xc->pkt_size = nla_get_u32(attrs[XFRMA_IPTFS_PKT_SIZE]);
@@ -79,6 +573,15 @@ static int iptfs_user_init(struct net *net, struct xfrm_state *x,
return -EINVAL;
}
}
+ if (attrs[XFRMA_IPTFS_MAX_QSIZE])
+ xc->max_queue_size = nla_get_u32(attrs[XFRMA_IPTFS_MAX_QSIZE]);
+ if (attrs[XFRMA_IPTFS_INIT_DELAY])
+ xtfs->init_delay_ns =
+ (u64)nla_get_u32(attrs[XFRMA_IPTFS_INIT_DELAY]) *
+ NSECS_IN_USEC;
+
+ xtfs->ecn_queue_size = (u64)xc->max_queue_size * 95 / 100;
+
return 0;
}
@@ -91,7 +594,7 @@ static unsigned int iptfs_sa_len(const struct xfrm_state *x)
l += nla_total_size(0);
l += nla_total_size(sizeof(u16));
l += nla_total_size(sizeof(xc->pkt_size));
- l += nla_total_size(sizeof(u32));
+ l += nla_total_size(sizeof(xc->max_queue_size));
l += nla_total_size(sizeof(u32)); /* drop time usec */
l += nla_total_size(sizeof(u32)); /* init delay usec */
@@ -103,6 +606,7 @@ static int iptfs_copy_to_user(struct xfrm_state *x, struct sk_buff *skb)
struct xfrm_iptfs_data *xtfs = x->mode_data;
struct xfrm_iptfs_config *xc = &xtfs->cfg;
int ret;
+ u64 q;
ret = nla_put_flag(skb, XFRMA_IPTFS_DONT_FRAG);
if (ret)
@@ -113,7 +617,7 @@ static int iptfs_copy_to_user(struct xfrm_state *x, struct sk_buff *skb)
ret = nla_put_u32(skb, XFRMA_IPTFS_PKT_SIZE, xc->pkt_size);
if (ret)
return ret;
- ret = nla_put_u32(skb, XFRMA_IPTFS_MAX_QSIZE, 0);
+ ret = nla_put_u32(skb, XFRMA_IPTFS_MAX_QSIZE, xc->max_queue_size);
if (ret)
return ret;
@@ -121,7 +625,9 @@ static int iptfs_copy_to_user(struct xfrm_state *x, struct sk_buff *skb)
if (ret)
return ret;
- ret = nla_put_u32(skb, XFRMA_IPTFS_INIT_DELAY, 0);
+ q = xtfs->init_delay_ns;
+ (void)do_div(q, NSECS_IN_USEC);
+ ret = nla_put_u32(skb, XFRMA_IPTFS_INIT_DELAY, q);
return ret;
}
@@ -129,6 +635,10 @@ static int iptfs_copy_to_user(struct xfrm_state *x, struct sk_buff *skb)
static int __iptfs_init_state(struct xfrm_state *x,
struct xfrm_iptfs_data *xtfs)
{
+ __skb_queue_head_init(&xtfs->queue);
+ hrtimer_init(&xtfs->iptfs_timer, CLOCK_MONOTONIC, IPTFS_HRTIMER_MODE);
+ xtfs->iptfs_timer.function = iptfs_delay_timer;
+
/* Modify type (esp) adjustment values */
if (x->props.family == AF_INET)
@@ -186,6 +696,7 @@ static void iptfs_delete_state(struct xfrm_state *x)
if (!xtfs)
return;
+ hrtimer_cancel(&xtfs->iptfs_timer);
kfree_sensitive(xtfs);
module_put(x->mode_cbs->owner);
@@ -200,6 +711,8 @@ static const struct xfrm_mode_cbs iptfs_mode_cbs = {
.sa_len = iptfs_sa_len,
.clone = iptfs_clone,
.get_inner_mtu = iptfs_get_inner_mtu,
+ .output = iptfs_output_collect,
+ .prepare_output = iptfs_prepare_output,
};
static int __init xfrm_iptfs_init(void)
--
2.45.1
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