xfrm: Add support for per cpu xfrm state handling.

Currently all flows for a certain SA must be processed by the same
cpu to avoid packet reordering and lock contention of the xfrm
state lock.

To get rid of this limitation, the IETF standardized per cpu SAs
in RFC 9611. This patch implements the xfrm part of it.

We add the cpu as a lookup key for xfrm states and a config option
to generate acquire messages for each cpu.

With that, we can have on each cpu a SA with identical traffic selector
so that flows can be processed in parallel on all cpus.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Tested-by: Antony Antony <antony.antony@secunet.com>
Tested-by: Tobias Brunner <tobias@strongswan.org>

Author: klassert

include/net/xfrm.h

@@ -188,6 +188,7 @@ struct xfrm_state {
 	refcount_t		refcnt;
 	spinlock_t		lock;
 
+	u32			pcpu_num;
 	struct xfrm_id		id;
 	struct xfrm_selector	sel;
 	struct xfrm_mark	mark;
@@ -1684,7 +1685,7 @@ struct xfrmk_spdinfo {
 	u32 spdhmcnt;
 };
 
-struct xfrm_state *xfrm_find_acq_byseq(struct net *net, u32 mark, u32 seq);
+struct xfrm_state *xfrm_find_acq_byseq(struct net *net, u32 mark, u32 seq, u32 pcpu_num);
 int xfrm_state_delete(struct xfrm_state *x);
 int xfrm_state_flush(struct net *net, u8 proto, bool task_valid, bool sync);
 int xfrm_dev_state_flush(struct net *net, struct net_device *dev, bool task_valid);
@@ -1796,7 +1797,7 @@ int verify_spi_info(u8 proto, u32 min, u32 max, struct netlink_ext_ack *extack);
 int xfrm_alloc_spi(struct xfrm_state *x, u32 minspi, u32 maxspi,
 		   struct netlink_ext_ack *extack);
 struct xfrm_state *xfrm_find_acq(struct net *net, const struct xfrm_mark *mark,
-				 u8 mode, u32 reqid, u32 if_id, u8 proto,
+				 u8 mode, u32 reqid, u32 if_id, u32 pcpu_num, u8 proto,
 				 const xfrm_address_t *daddr,
 				 const xfrm_address_t *saddr, int create,
 				 unsigned short family);

include/uapi/linux/xfrm.h

@@ -322,6 +322,7 @@ enum xfrm_attr_type_t {
 	XFRMA_MTIMER_THRESH,	/* __u32 in seconds for input SA */
 	XFRMA_SA_DIR,		/* __u8 */
 	XFRMA_NAT_KEEPALIVE_INTERVAL,	/* __u32 in seconds for NAT keepalive */
+	XFRMA_SA_PCPU,		/* __u32 */
 	__XFRMA_MAX
 
 #define XFRMA_OUTPUT_MARK XFRMA_SET_MARK	/* Compatibility */
@@ -437,6 +438,7 @@ struct xfrm_userpolicy_info {
 #define XFRM_POLICY_LOCALOK	1	/* Allow user to override global policy */
 	/* Automatically expand selector to include matching ICMP payloads. */
 #define XFRM_POLICY_ICMP	2
+#define XFRM_POLICY_CPU_ACQUIRE	4
 	__u8				share;
 };
 

net/key/af_key.c

@@ -1354,15 +1354,16 @@ static int pfkey_getspi(struct sock *sk, struct sk_buff *skb, const struct sadb_
 	}
 
 	if (hdr->sadb_msg_seq) {
-		x = xfrm_find_acq_byseq(net, DUMMY_MARK, hdr->sadb_msg_seq);
+		x = xfrm_find_acq_byseq(net, DUMMY_MARK, hdr->sadb_msg_seq, UINT_MAX);
 		if (x && !xfrm_addr_equal(&x->id.daddr, xdaddr, family)) {
 			xfrm_state_put(x);
 			x = NULL;
 		}
 	}
 
 	if (!x)
-		x = xfrm_find_acq(net, &dummy_mark, mode, reqid, 0, proto, xdaddr, xsaddr, 1, family);
+		x = xfrm_find_acq(net, &dummy_mark, mode, reqid, 0, UINT_MAX,
+				  proto, xdaddr, xsaddr, 1, family);
 
 	if (x == NULL)
 		return -ENOENT;
@@ -1417,7 +1418,7 @@ static int pfkey_acquire(struct sock *sk, struct sk_buff *skb, const struct sadb
 	if (hdr->sadb_msg_seq == 0 || hdr->sadb_msg_errno == 0)
 		return 0;
 
-	x = xfrm_find_acq_byseq(net, DUMMY_MARK, hdr->sadb_msg_seq);
+	x = xfrm_find_acq_byseq(net, DUMMY_MARK, hdr->sadb_msg_seq, UINT_MAX);
 	if (x == NULL)
 		return 0;
 

net/xfrm/xfrm_compat.c

@@ -132,6 +132,7 @@ static const struct nla_policy compat_policy[XFRMA_MAX+1] = {
 	[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 },
+	[XFRMA_SA_PCPU]		= { .type = NLA_U32 },
 };
 
 static struct nlmsghdr *xfrm_nlmsg_put_compat(struct sk_buff *skb,
@@ -282,9 +283,10 @@ static int xfrm_xlate64_attr(struct sk_buff *dst, const struct nlattr *src)
 	case XFRMA_MTIMER_THRESH:
 	case XFRMA_SA_DIR:
 	case XFRMA_NAT_KEEPALIVE_INTERVAL:
+	case XFRMA_SA_PCPU:
 		return xfrm_nla_cpy(dst, src, nla_len(src));
 	default:
-		BUILD_BUG_ON(XFRMA_MAX != XFRMA_NAT_KEEPALIVE_INTERVAL);
+		BUILD_BUG_ON(XFRMA_MAX != XFRMA_SA_PCPU);
 		pr_warn_once("unsupported nla_type %d\n", src->nla_type);
 		return -EOPNOTSUPP;
 	}
@@ -439,7 +441,7 @@ static int xfrm_xlate32_attr(void *dst, const struct nlattr *nla,
 	int err;
 
 	if (type > XFRMA_MAX) {
-		BUILD_BUG_ON(XFRMA_MAX != XFRMA_NAT_KEEPALIVE_INTERVAL);
+		BUILD_BUG_ON(XFRMA_MAX != XFRMA_SA_PCPU);
 		NL_SET_ERR_MSG(extack, "Bad attribute");
 		return -EOPNOTSUPP;
 	}

net/xfrm/xfrm_state.c

@@ -679,6 +679,7 @@ struct xfrm_state *xfrm_state_alloc(struct net *net)
 		x->lft.hard_packet_limit = XFRM_INF;
 		x->replay_maxage = 0;
 		x->replay_maxdiff = 0;
+		x->pcpu_num = UINT_MAX;
 		spin_lock_init(&x->lock);
 	}
 	return x;
@@ -1155,6 +1156,12 @@ static void xfrm_state_look_at(struct xfrm_policy *pol, struct xfrm_state *x,
 			       struct xfrm_state **best, int *acq_in_progress,
 			       int *error)
 {
+	/* We need the cpu id just as a lookup key,
+	 * we don't require it to be stable.
+	 */
+	unsigned int pcpu_id = get_cpu();
+	put_cpu();
+
 	/* Resolution logic:
 	 * 1. There is a valid state with matching selector. Done.
 	 * 2. Valid state with inappropriate selector. Skip.
@@ -1174,13 +1181,18 @@ static void xfrm_state_look_at(struct xfrm_policy *pol, struct xfrm_state *x,
 							&fl->u.__fl_common))
 			return;
 
+		if (x->pcpu_num != UINT_MAX && x->pcpu_num != pcpu_id)
+			return;
+
 		if (!*best ||
+		    ((*best)->pcpu_num == UINT_MAX && x->pcpu_num == pcpu_id) ||
 		    (*best)->km.dying > x->km.dying ||
 		    ((*best)->km.dying == x->km.dying &&
 		     (*best)->curlft.add_time < x->curlft.add_time))
 			*best = x;
 	} else if (x->km.state == XFRM_STATE_ACQ) {
-		*acq_in_progress = 1;
+		if (!*best || x->pcpu_num == pcpu_id)
+			*acq_in_progress = 1;
 	} else if (x->km.state == XFRM_STATE_ERROR ||
 		   x->km.state == XFRM_STATE_EXPIRED) {
 		if ((!x->sel.family ||
@@ -1209,6 +1221,13 @@ xfrm_state_find(const xfrm_address_t *daddr, const xfrm_address_t *saddr,
 	unsigned short encap_family = tmpl->encap_family;
 	unsigned int sequence;
 	struct km_event c;
+	unsigned int pcpu_id;
+
+	/* We need the cpu id just as a lookup key,
+	 * we don't require it to be stable.
+	 */
+	pcpu_id = get_cpu();
+	put_cpu();
 
 	to_put = NULL;
 
@@ -1282,7 +1301,10 @@ xfrm_state_find(const xfrm_address_t *daddr, const xfrm_address_t *saddr,
 	}
 
 found:
-	x = best;
+	if (!(pol->flags & XFRM_POLICY_CPU_ACQUIRE) ||
+	    (best && (best->pcpu_num == pcpu_id)))
+		x = best;
+
 	if (!x && !error && !acquire_in_progress) {
 		if (tmpl->id.spi &&
 		    (x0 = __xfrm_state_lookup_all(net, mark, daddr,
@@ -1314,6 +1336,8 @@ xfrm_state_find(const xfrm_address_t *daddr, const xfrm_address_t *saddr,
 		xfrm_init_tempstate(x, fl, tmpl, daddr, saddr, family);
 		memcpy(&x->mark, &pol->mark, sizeof(x->mark));
 		x->if_id = if_id;
+		if ((pol->flags & XFRM_POLICY_CPU_ACQUIRE) && best)
+			x->pcpu_num = pcpu_id;
 
 		error = security_xfrm_state_alloc_acquire(x, pol->security, fl->flowi_secid);
 		if (error) {
@@ -1392,6 +1416,11 @@ xfrm_state_find(const xfrm_address_t *daddr, const xfrm_address_t *saddr,
 			x = NULL;
 			error = -ESRCH;
 		}
+
+		/* Use the already installed 'fallback' while the CPU-specific
+		 * SA acquire is handled*/
+		if (best)
+			x = best;
 	}
 out:
 	if (x) {
@@ -1524,12 +1553,14 @@ static void __xfrm_state_bump_genids(struct xfrm_state *xnew)
 	unsigned int h;
 	u32 mark = xnew->mark.v & xnew->mark.m;
 	u32 if_id = xnew->if_id;
+	u32 cpu_id = xnew->pcpu_num;
 
 	h = xfrm_dst_hash(net, &xnew->id.daddr, &xnew->props.saddr, reqid, family);
 	hlist_for_each_entry(x, net->xfrm.state_bydst+h, bydst) {
 		if (x->props.family	== family &&
 		    x->props.reqid	== reqid &&
 		    x->if_id		== if_id &&
+		    x->pcpu_num		== cpu_id &&
 		    (mark & x->mark.m) == x->mark.v &&
 		    xfrm_addr_equal(&x->id.daddr, &xnew->id.daddr, family) &&
 		    xfrm_addr_equal(&x->props.saddr, &xnew->props.saddr, family))
@@ -1552,7 +1583,7 @@ EXPORT_SYMBOL(xfrm_state_insert);
 static struct xfrm_state *__find_acq_core(struct net *net,
 					  const struct xfrm_mark *m,
 					  unsigned short family, u8 mode,
-					  u32 reqid, u32 if_id, u8 proto,
+					  u32 reqid, u32 if_id, u32 pcpu_num, u8 proto,
 					  const xfrm_address_t *daddr,
 					  const xfrm_address_t *saddr,
 					  int create)
@@ -1569,6 +1600,7 @@ static struct xfrm_state *__find_acq_core(struct net *net,
 		    x->id.spi       != 0 ||
 		    x->id.proto	    != proto ||
 		    (mark & x->mark.m) != x->mark.v ||
+		    x->pcpu_num != pcpu_num ||
 		    !xfrm_addr_equal(&x->id.daddr, daddr, family) ||
 		    !xfrm_addr_equal(&x->props.saddr, saddr, family))
 			continue;
@@ -1602,6 +1634,7 @@ static struct xfrm_state *__find_acq_core(struct net *net,
 			break;
 		}
 
+		x->pcpu_num = pcpu_num;
 		x->km.state = XFRM_STATE_ACQ;
 		x->id.proto = proto;
 		x->props.family = family;
@@ -1630,7 +1663,7 @@ static struct xfrm_state *__find_acq_core(struct net *net,
 	return x;
 }
 
-static struct xfrm_state *__xfrm_find_acq_byseq(struct net *net, u32 mark, u32 seq);
+static struct xfrm_state *__xfrm_find_acq_byseq(struct net *net, u32 mark, u32 seq, u32 pcpu_num);
 
 int xfrm_state_add(struct xfrm_state *x)
 {
@@ -1656,7 +1689,7 @@ int xfrm_state_add(struct xfrm_state *x)
 	}
 
 	if (use_spi && x->km.seq) {
-		x1 = __xfrm_find_acq_byseq(net, mark, x->km.seq);
+		x1 = __xfrm_find_acq_byseq(net, mark, x->km.seq, x->pcpu_num);
 		if (x1 && ((x1->id.proto != x->id.proto) ||
 		    !xfrm_addr_equal(&x1->id.daddr, &x->id.daddr, family))) {
 			to_put = x1;
@@ -1666,7 +1699,7 @@ int xfrm_state_add(struct xfrm_state *x)
 
 	if (use_spi && !x1)
 		x1 = __find_acq_core(net, &x->mark, family, x->props.mode,
-				     x->props.reqid, x->if_id, x->id.proto,
+				     x->props.reqid, x->if_id, x->pcpu_num, x->id.proto,
 				     &x->id.daddr, &x->props.saddr, 0);
 
 	__xfrm_state_bump_genids(x);
@@ -1791,6 +1824,7 @@ static struct xfrm_state *xfrm_state_clone(struct xfrm_state *orig,
 	x->props.flags = orig->props.flags;
 	x->props.extra_flags = orig->props.extra_flags;
 
+	x->pcpu_num = orig->pcpu_num;
 	x->if_id = orig->if_id;
 	x->tfcpad = orig->tfcpad;
 	x->replay_maxdiff = orig->replay_maxdiff;
@@ -2066,13 +2100,14 @@ EXPORT_SYMBOL(xfrm_state_lookup_byaddr);
 
 struct xfrm_state *
 xfrm_find_acq(struct net *net, const struct xfrm_mark *mark, u8 mode, u32 reqid,
-	      u32 if_id, u8 proto, const xfrm_address_t *daddr,
+	      u32 if_id, u32 pcpu_num, u8 proto, const xfrm_address_t *daddr,
 	      const xfrm_address_t *saddr, int create, unsigned short family)
 {
 	struct xfrm_state *x;
 
 	spin_lock_bh(&net->xfrm.xfrm_state_lock);
-	x = __find_acq_core(net, mark, family, mode, reqid, if_id, proto, daddr, saddr, create);
+	x = __find_acq_core(net, mark, family, mode, reqid, if_id, pcpu_num,
+			    proto, daddr, saddr, create);
 	spin_unlock_bh(&net->xfrm.xfrm_state_lock);
 
 	return x;
@@ -2207,14 +2242,15 @@ xfrm_state_sort(struct xfrm_state **dst, struct xfrm_state **src, int n,
 
 /* Silly enough, but I'm lazy to build resolution list */
 
-static struct xfrm_state *__xfrm_find_acq_byseq(struct net *net, u32 mark, u32 seq)
+static struct xfrm_state *__xfrm_find_acq_byseq(struct net *net, u32 mark, u32 seq, u32 pcpu_num)
 {
 	unsigned int h = xfrm_seq_hash(net, seq);
 	struct xfrm_state *x;
 
 	hlist_for_each_entry_rcu(x, net->xfrm.state_byseq + h, byseq) {
 		if (x->km.seq == seq &&
 		    (mark & x->mark.m) == x->mark.v &&
+		    x->pcpu_num == pcpu_num &&
 		    x->km.state == XFRM_STATE_ACQ) {
 			xfrm_state_hold(x);
 			return x;
@@ -2224,12 +2260,12 @@ static struct xfrm_state *__xfrm_find_acq_byseq(struct net *net, u32 mark, u32 s
 	return NULL;
 }
 
-struct xfrm_state *xfrm_find_acq_byseq(struct net *net, u32 mark, u32 seq)
+struct xfrm_state *xfrm_find_acq_byseq(struct net *net, u32 mark, u32 seq, u32 pcpu_num)
 {
 	struct xfrm_state *x;
 
 	spin_lock_bh(&net->xfrm.xfrm_state_lock);
-	x = __xfrm_find_acq_byseq(net, mark, seq);
+	x = __xfrm_find_acq_byseq(net, mark, seq, pcpu_num);
 	spin_unlock_bh(&net->xfrm.xfrm_state_lock);
 	return x;
 }