Merge branch 'faster-soreuseport'

Craig Gallek says:

====================
Faster SO_REUSEPORT

This series contains two optimizations for the SO_REUSEPORT feature:
Faster lookup when selecting a socket for an incoming packet and
the ability to select the socket from the group using a BPF program.

This series only includes the UDP path.  I plan to submit a follow-up
including the TCP path if the implementation in this series is
acceptable.

Changes in v4:
- pskb_may_pull is unnecessary with pskb_pull (per Alexei Starovoitov)

Changes in v3:
- skb_pull_inline -> pskb_pull (per Alexei Starovoitov)
- reuseport_attach* -> sk_reuseport_attach* and simple return statement
  syntax change (per Daniel Borkmann)

Changes in v2:
- Fix ARM build; remove unnecessary include.
- Handle case where protocol header is not in linear section (per
  Alexei Starovoitov).
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/alpha/include/uapi/asm/socket.h

@@ -92,4 +92,7 @@
 #define SO_ATTACH_BPF		50
 #define SO_DETACH_BPF		SO_DETACH_FILTER
 
+#define SO_ATTACH_REUSEPORT_CBPF	51
+#define SO_ATTACH_REUSEPORT_EBPF	52
+
 #endif /* _UAPI_ASM_SOCKET_H */

arch/avr32/include/uapi/asm/socket.h

@@ -85,4 +85,7 @@
 #define SO_ATTACH_BPF		50
 #define SO_DETACH_BPF		SO_DETACH_FILTER
 
+#define SO_ATTACH_REUSEPORT_CBPF	51
+#define SO_ATTACH_REUSEPORT_EBPF	52
+
 #endif /* _UAPI__ASM_AVR32_SOCKET_H */

arch/frv/include/uapi/asm/socket.h

@@ -85,5 +85,8 @@
 #define SO_ATTACH_BPF		50
 #define SO_DETACH_BPF		SO_DETACH_FILTER
 
+#define SO_ATTACH_REUSEPORT_CBPF	51
+#define SO_ATTACH_REUSEPORT_EBPF	52
+
 #endif /* _ASM_SOCKET_H */
 

arch/ia64/include/uapi/asm/socket.h

@@ -94,4 +94,7 @@
 #define SO_ATTACH_BPF		50
 #define SO_DETACH_BPF		SO_DETACH_FILTER
 
+#define SO_ATTACH_REUSEPORT_CBPF	51
+#define SO_ATTACH_REUSEPORT_EBPF	52
+
 #endif /* _ASM_IA64_SOCKET_H */

arch/m32r/include/uapi/asm/socket.h

@@ -85,4 +85,7 @@
 #define SO_ATTACH_BPF		50
 #define SO_DETACH_BPF		SO_DETACH_FILTER
 
+#define SO_ATTACH_REUSEPORT_CBPF	51
+#define SO_ATTACH_REUSEPORT_EBPF	52
+
 #endif /* _ASM_M32R_SOCKET_H */

arch/mips/include/uapi/asm/socket.h

@@ -103,4 +103,7 @@
 #define SO_ATTACH_BPF		50
 #define SO_DETACH_BPF		SO_DETACH_FILTER
 
+#define SO_ATTACH_REUSEPORT_CBPF	51
+#define SO_ATTACH_REUSEPORT_EBPF	52
+
 #endif /* _UAPI_ASM_SOCKET_H */

arch/mn10300/include/uapi/asm/socket.h

@@ -85,4 +85,7 @@
 #define SO_ATTACH_BPF		50
 #define SO_DETACH_BPF		SO_DETACH_FILTER
 
+#define SO_ATTACH_REUSEPORT_CBPF	51
+#define SO_ATTACH_REUSEPORT_EBPF	52
+
 #endif /* _ASM_SOCKET_H */

arch/parisc/include/uapi/asm/socket.h

@@ -84,4 +84,7 @@
 #define SO_ATTACH_BPF		0x402B
 #define SO_DETACH_BPF		SO_DETACH_FILTER
 
+#define SO_ATTACH_REUSEPORT_CBPF	0x402C
+#define SO_ATTACH_REUSEPORT_EBPF	0x402D
+
 #endif /* _UAPI_ASM_SOCKET_H */

arch/powerpc/include/uapi/asm/socket.h

@@ -92,4 +92,7 @@
 #define SO_ATTACH_BPF		50
 #define SO_DETACH_BPF		SO_DETACH_FILTER
 
+#define SO_ATTACH_REUSEPORT_CBPF	51
+#define SO_ATTACH_REUSEPORT_EBPF	52
+
 #endif	/* _ASM_POWERPC_SOCKET_H */

arch/s390/include/uapi/asm/socket.h

@@ -91,4 +91,7 @@
 #define SO_ATTACH_BPF		50
 #define SO_DETACH_BPF		SO_DETACH_FILTER
 
+#define SO_ATTACH_REUSEPORT_CBPF	51
+#define SO_ATTACH_REUSEPORT_EBPF	52
+
 #endif /* _ASM_SOCKET_H */

arch/sparc/include/uapi/asm/socket.h

@@ -81,6 +81,9 @@
 #define SO_ATTACH_BPF		0x0034
 #define SO_DETACH_BPF		SO_DETACH_FILTER
 
+#define SO_ATTACH_REUSEPORT_CBPF	0x0035
+#define SO_ATTACH_REUSEPORT_EBPF	0x0036
+
 /* Security levels - as per NRL IPv6 - don't actually do anything */
 #define SO_SECURITY_AUTHENTICATION		0x5001
 #define SO_SECURITY_ENCRYPTION_TRANSPORT	0x5002

arch/xtensa/include/uapi/asm/socket.h

@@ -96,4 +96,7 @@
 #define SO_ATTACH_BPF		50
 #define SO_DETACH_BPF		SO_DETACH_FILTER
 
+#define SO_ATTACH_REUSEPORT_CBPF	51
+#define SO_ATTACH_REUSEPORT_EBPF	52
+
 #endif	/* _XTENSA_SOCKET_H */

include/linux/filter.h

@@ -447,6 +447,8 @@ void bpf_prog_destroy(struct bpf_prog *fp);
 
 int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
 int sk_attach_bpf(u32 ufd, struct sock *sk);
+int sk_reuseport_attach_filter(struct sock_fprog *fprog, struct sock *sk);
+int sk_reuseport_attach_bpf(u32 ufd, struct sock *sk);
 int sk_detach_filter(struct sock *sk);
 int sk_get_filter(struct sock *sk, struct sock_filter __user *filter,
 		  unsigned int len);

include/net/addrconf.h

@@ -87,7 +87,8 @@ int __ipv6_get_lladdr(struct inet6_dev *idev, struct in6_addr *addr,
 		      u32 banned_flags);
 int ipv6_get_lladdr(struct net_device *dev, struct in6_addr *addr,
 		    u32 banned_flags);
-int ipv6_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2);
+int ipv6_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
+			 bool match_wildcard);
 void addrconf_join_solict(struct net_device *dev, const struct in6_addr *addr);
 void addrconf_leave_solict(struct inet6_dev *idev, const struct in6_addr *addr);
 

include/net/sock.h

@@ -318,6 +318,7 @@ struct cg_proto;
   *	@sk_error_report: callback to indicate errors (e.g. %MSG_ERRQUEUE)
   *	@sk_backlog_rcv: callback to process the backlog
   *	@sk_destruct: called at sock freeing time, i.e. when all refcnt == 0
+  *	@sk_reuseport_cb: reuseport group container
  */
 struct sock {
 	/*
@@ -453,6 +454,7 @@ struct sock {
 	int			(*sk_backlog_rcv)(struct sock *sk,
 						  struct sk_buff *skb);
 	void                    (*sk_destruct)(struct sock *sk);
+	struct sock_reuseport __rcu	*sk_reuseport_cb;
 };
 
 #define __sk_user_data(sk) ((*((void __rcu **)&(sk)->sk_user_data)))

include/net/sock_reuseport.h

+#ifndef _SOCK_REUSEPORT_H
+#define _SOCK_REUSEPORT_H
+
+#include <linux/filter.h>
+#include <linux/skbuff.h>
+#include <linux/types.h>
+#include <net/sock.h>
+
+struct sock_reuseport {
+	struct rcu_head		rcu;
+
+	u16			max_socks;	/* length of socks */
+	u16			num_socks;	/* elements in socks */
+	struct bpf_prog __rcu	*prog;		/* optional BPF sock selector */
+	struct sock		*socks[0];	/* array of sock pointers */
+};
+
+extern int reuseport_alloc(struct sock *sk);
+extern int reuseport_add_sock(struct sock *sk, const struct sock *sk2);
+extern void reuseport_detach_sock(struct sock *sk);
+extern struct sock *reuseport_select_sock(struct sock *sk,
+					  u32 hash,
+					  struct sk_buff *skb,
+					  int hdr_len);
+extern struct bpf_prog *reuseport_attach_prog(struct sock *sk,
+					      struct bpf_prog *prog);
+
+#endif  /* _SOCK_REUSEPORT_H */

include/net/udp.h

@@ -191,7 +191,7 @@ static inline void udp_lib_close(struct sock *sk, long timeout)
 }
 
 int udp_lib_get_port(struct sock *sk, unsigned short snum,
-		     int (*)(const struct sock *, const struct sock *),
+		     int (*)(const struct sock *, const struct sock *, bool),
 		     unsigned int hash2_nulladdr);
 
 u32 udp_flow_hashrnd(void);
@@ -258,7 +258,7 @@ struct sock *udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
 			     __be32 daddr, __be16 dport, int dif);
 struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
 			       __be32 daddr, __be16 dport, int dif,
-			       struct udp_table *tbl);
+			       struct udp_table *tbl, struct sk_buff *skb);
 struct sock *udp6_lib_lookup(struct net *net,
 			     const struct in6_addr *saddr, __be16 sport,
 			     const struct in6_addr *daddr, __be16 dport,
@@ -266,7 +266,8 @@ struct sock *udp6_lib_lookup(struct net *net,
 struct sock *__udp6_lib_lookup(struct net *net,
 			       const struct in6_addr *saddr, __be16 sport,
 			       const struct in6_addr *daddr, __be16 dport,
-			       int dif, struct udp_table *tbl);
+			       int dif, struct udp_table *tbl,
+			       struct sk_buff *skb);
 
 /*
  * 	SNMP statistics for UDP and UDP-Lite

include/uapi/asm-generic/socket.h

@@ -87,4 +87,7 @@
 #define SO_ATTACH_BPF		50
 #define SO_DETACH_BPF		SO_DETACH_FILTER
 
+#define SO_ATTACH_REUSEPORT_CBPF	51
+#define SO_ATTACH_REUSEPORT_EBPF	52
+
 #endif /* __ASM_GENERIC_SOCKET_H */

net/core/Makefile

@@ -9,7 +9,7 @@ obj-$(CONFIG_SYSCTL) += sysctl_net_core.o
 
 obj-y		     += dev.o ethtool.o dev_addr_lists.o dst.o netevent.o \
 			neighbour.o rtnetlink.o utils.o link_watch.o filter.o \
-			sock_diag.o dev_ioctl.o tso.o
+			sock_diag.o dev_ioctl.o tso.o sock_reuseport.o
 
 obj-$(CONFIG_XFRM) += flow.o
 obj-y += net-sysfs.o

net/core/filter.c

@@ -50,6 +50,7 @@
 #include <net/cls_cgroup.h>
 #include <net/dst_metadata.h>
 #include <net/dst.h>
+#include <net/sock_reuseport.h>
 
 /**
  *	sk_filter - run a packet through a socket filter
@@ -1167,17 +1168,32 @@ static int __sk_attach_prog(struct bpf_prog *prog, struct sock *sk)
 	return 0;
 }
 
-/**
- *	sk_attach_filter - attach a socket filter
- *	@fprog: the filter program
- *	@sk: the socket to use
- *
- * Attach the user's filter code. We first run some sanity checks on
- * it to make sure it does not explode on us later. If an error
- * occurs or there is insufficient memory for the filter a negative
- * errno code is returned. On success the return is zero.
- */
-int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
+static int __reuseport_attach_prog(struct bpf_prog *prog, struct sock *sk)
+{
+	struct bpf_prog *old_prog;
+	int err;
+
+	if (bpf_prog_size(prog->len) > sysctl_optmem_max)
+		return -ENOMEM;
+
+	if (sk_unhashed(sk)) {
+		err = reuseport_alloc(sk);
+		if (err)
+			return err;
+	} else if (!rcu_access_pointer(sk->sk_reuseport_cb)) {
+		/* The socket wasn't bound with SO_REUSEPORT */
+		return -EINVAL;
+	}
+
+	old_prog = reuseport_attach_prog(sk, prog);
+	if (old_prog)
+		bpf_prog_destroy(old_prog);
+
+	return 0;
+}
+
+static
+struct bpf_prog *__get_filter(struct sock_fprog *fprog, struct sock *sk)
 {
 	unsigned int fsize = bpf_classic_proglen(fprog);
 	unsigned int bpf_fsize = bpf_prog_size(fprog->len);
@@ -1185,19 +1201,19 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
 	int err;
 
 	if (sock_flag(sk, SOCK_FILTER_LOCKED))
-		return -EPERM;
+		return ERR_PTR(-EPERM);
 
 	/* Make sure new filter is there and in the right amounts. */
 	if (fprog->filter == NULL)
-		return -EINVAL;
+		return ERR_PTR(-EINVAL);
 
 	prog = bpf_prog_alloc(bpf_fsize, 0);
 	if (!prog)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	if (copy_from_user(prog->insns, fprog->filter, fsize)) {
 		__bpf_prog_free(prog);
-		return -EFAULT;
+		return ERR_PTR(-EFAULT);
 	}
 
 	prog->len = fprog->len;
@@ -1205,13 +1221,30 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
 	err = bpf_prog_store_orig_filter(prog, fprog);
 	if (err) {
 		__bpf_prog_free(prog);
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 	}
 
 	/* bpf_prepare_filter() already takes care of freeing
 	 * memory in case something goes wrong.
 	 */
-	prog = bpf_prepare_filter(prog, NULL);
+	return bpf_prepare_filter(prog, NULL);
+}
+
+/**
+ *	sk_attach_filter - attach a socket filter
+ *	@fprog: the filter program
+ *	@sk: the socket to use
+ *
+ * Attach the user's filter code. We first run some sanity checks on
+ * it to make sure it does not explode on us later. If an error
+ * occurs or there is insufficient memory for the filter a negative
+ * errno code is returned. On success the return is zero.
+ */
+int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
+{
+	struct bpf_prog *prog = __get_filter(fprog, sk);
+	int err;
+
 	if (IS_ERR(prog))
 		return PTR_ERR(prog);
 
@@ -1225,23 +1258,50 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
 }
 EXPORT_SYMBOL_GPL(sk_attach_filter);
 
-int sk_attach_bpf(u32 ufd, struct sock *sk)
+int sk_reuseport_attach_filter(struct sock_fprog *fprog, struct sock *sk)
 {
-	struct bpf_prog *prog;
+	struct bpf_prog *prog = __get_filter(fprog, sk);
 	int err;
 
+	if (IS_ERR(prog))
+		return PTR_ERR(prog);
+
+	err = __reuseport_attach_prog(prog, sk);
+	if (err < 0) {
+		__bpf_prog_release(prog);
+		return err;
+	}
+
+	return 0;
+}
+
+static struct bpf_prog *__get_bpf(u32 ufd, struct sock *sk)
+{
+	struct bpf_prog *prog;
+
 	if (sock_flag(sk, SOCK_FILTER_LOCKED))
-		return -EPERM;
+		return ERR_PTR(-EPERM);
 
 	prog = bpf_prog_get(ufd);
 	if (IS_ERR(prog))
-		return PTR_ERR(prog);
+		return prog;
 
 	if (prog->type != BPF_PROG_TYPE_SOCKET_FILTER) {
 		bpf_prog_put(prog);
-		return -EINVAL;
+		return ERR_PTR(-EINVAL);
 	}
 
+	return prog;
+}
+
+int sk_attach_bpf(u32 ufd, struct sock *sk)
+{
+	struct bpf_prog *prog = __get_bpf(ufd, sk);
+	int err;
+
+	if (IS_ERR(prog))
+		return PTR_ERR(prog);
+
 	err = __sk_attach_prog(prog, sk);
 	if (err < 0) {
 		bpf_prog_put(prog);
@@ -1251,6 +1311,23 @@ int sk_attach_bpf(u32 ufd, struct sock *sk)
 	return 0;
 }
 
+int sk_reuseport_attach_bpf(u32 ufd, struct sock *sk)
+{
+	struct bpf_prog *prog = __get_bpf(ufd, sk);
+	int err;
+
+	if (IS_ERR(prog))
+		return PTR_ERR(prog);
+
+	err = __reuseport_attach_prog(prog, sk);
+	if (err < 0) {
+		bpf_prog_put(prog);
+		return err;
+	}
+
+	return 0;
+}
+
 #define BPF_RECOMPUTE_CSUM(flags)	((flags) & 1)
 #define BPF_LDST_LEN			16U
 

net/core/sock.c

@@ -134,6 +134,7 @@
 #include <linux/sock_diag.h>
 
 #include <linux/filter.h>
+#include <net/sock_reuseport.h>
 
 #include <trace/events/sock.h>
 
@@ -932,6 +933,32 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
 		}
 		break;
 
+	case SO_ATTACH_REUSEPORT_CBPF:
+		ret = -EINVAL;
+		if (optlen == sizeof(struct sock_fprog)) {
+			struct sock_fprog fprog;
+
+			ret = -EFAULT;
+			if (copy_from_user(&fprog, optval, sizeof(fprog)))
+				break;
+
+			ret = sk_reuseport_attach_filter(&fprog, sk);
+		}
+		break;
+
+	case SO_ATTACH_REUSEPORT_EBPF:
+		ret = -EINVAL;
+		if (optlen == sizeof(u32)) {
+			u32 ufd;
+
+			ret = -EFAULT;
+			if (copy_from_user(&ufd, optval, sizeof(ufd)))
+				break;
+
+			ret = sk_reuseport_attach_bpf(ufd, sk);
+		}
+		break;
+
 	case SO_DETACH_FILTER:
 		ret = sk_detach_filter(sk);
 		break;
@@ -1443,6 +1470,8 @@ void sk_destruct(struct sock *sk)
 		sk_filter_uncharge(sk, filter);
 		RCU_INIT_POINTER(sk->sk_filter, NULL);
 	}
+	if (rcu_access_pointer(sk->sk_reuseport_cb))
+		reuseport_detach_sock(sk);
 
 	sock_disable_timestamp(sk, SK_FLAGS_TIMESTAMP);
 

net/core/sock_reuseport.c

+/*
+ * To speed up listener socket lookup, create an array to store all sockets
+ * listening on the same port.  This allows a decision to be made after finding
+ * the first socket.  An optional BPF program can also be configured for
+ * selecting the socket index from the array of available sockets.
+ */
+
+#include <net/sock_reuseport.h>
+#include <linux/bpf.h>
+#include <linux/rcupdate.h>
+
+#define INIT_SOCKS 128
+
+static DEFINE_SPINLOCK(reuseport_lock);
+
+static struct sock_reuseport *__reuseport_alloc(u16 max_socks)
+{
+	size_t size = sizeof(struct sock_reuseport) +
+		      sizeof(struct sock *) * max_socks;
+	struct sock_reuseport *reuse = kzalloc(size, GFP_ATOMIC);
+
+	if (!reuse)
+		return NULL;
+
+	reuse->max_socks = max_socks;
+
+	RCU_INIT_POINTER(reuse->prog, NULL);
+	return reuse;
+}
+
+int reuseport_alloc(struct sock *sk)
+{
+	struct sock_reuseport *reuse;
+
+	/* bh lock used since this function call may precede hlist lock in
+	 * soft irq of receive path or setsockopt from process context
+	 */
+	spin_lock_bh(&reuseport_lock);
+	WARN_ONCE(rcu_dereference_protected(sk->sk_reuseport_cb,
+					    lockdep_is_held(&reuseport_lock)),
+		  "multiple allocations for the same socket");
+	reuse = __reuseport_alloc(INIT_SOCKS);
+	if (!reuse) {
+		spin_unlock_bh(&reuseport_lock);
+		return -ENOMEM;
+	}
+
+	reuse->socks[0] = sk;
+	reuse->num_socks = 1;
+	rcu_assign_pointer(sk->sk_reuseport_cb, reuse);
+
+	spin_unlock_bh(&reuseport_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL(reuseport_alloc);
+
+static struct sock_reuseport *reuseport_grow(struct sock_reuseport *reuse)
+{
+	struct sock_reuseport *more_reuse;
+	u32 more_socks_size, i;
+
+	more_socks_size = reuse->max_socks * 2U;
+	if (more_socks_size > U16_MAX)
+		return NULL;
+
+	more_reuse = __reuseport_alloc(more_socks_size);
+	if (!more_reuse)
+		return NULL;
+
+	more_reuse->max_socks = more_socks_size;
+	more_reuse->num_socks = reuse->num_socks;
+	more_reuse->prog = reuse->prog;
+
+	memcpy(more_reuse->socks, reuse->socks,
+	       reuse->num_socks * sizeof(struct sock *));
+
+	for (i = 0; i < reuse->num_socks; ++i)
+		rcu_assign_pointer(reuse->socks[i]->sk_reuseport_cb,
+				   more_reuse);
+
+	/* Note: we use kfree_rcu here instead of reuseport_free_rcu so
+	 * that reuse and more_reuse can temporarily share a reference
+	 * to prog.
+	 */
+	kfree_rcu(reuse, rcu);
+	return more_reuse;
+}
+
+/**
+ *  reuseport_add_sock - Add a socket to the reuseport group of another.
+ *  @sk:  New socket to add to the group.
+ *  @sk2: Socket belonging to the existing reuseport group.
+ *  May return ENOMEM and not add socket to group under memory pressure.
+ */
+int reuseport_add_sock(struct sock *sk, const struct sock *sk2)
+{
+	struct sock_reuseport *reuse;
+
+	spin_lock_bh(&reuseport_lock);
+	reuse = rcu_dereference_protected(sk2->sk_reuseport_cb,
+					  lockdep_is_held(&reuseport_lock)),
+	WARN_ONCE(rcu_dereference_protected(sk->sk_reuseport_cb,
+					    lockdep_is_held(&reuseport_lock)),
+		  "socket already in reuseport group");
+
+	if (reuse->num_socks == reuse->max_socks) {
+		reuse = reuseport_grow(reuse);
+		if (!reuse) {
+			spin_unlock_bh(&reuseport_lock);
+			return -ENOMEM;
+		}
+	}
+
+	reuse->socks[reuse->num_socks] = sk;
+	/* paired with smp_rmb() in reuseport_select_sock() */
+	smp_wmb();
+	reuse->num_socks++;
+	rcu_assign_pointer(sk->sk_reuseport_cb, reuse);
+
+	spin_unlock_bh(&reuseport_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL(reuseport_add_sock);
+
+static void reuseport_free_rcu(struct rcu_head *head)
+{
+	struct sock_reuseport *reuse;
+
+	reuse = container_of(head, struct sock_reuseport, rcu);
+	if (reuse->prog)
+		bpf_prog_destroy(reuse->prog);
+	kfree(reuse);
+}
+
+void reuseport_detach_sock(struct sock *sk)
+{
+	struct sock_reuseport *reuse;
+	int i;
+
+	spin_lock_bh(&reuseport_lock);
+	reuse = rcu_dereference_protected(sk->sk_reuseport_cb,
+					  lockdep_is_held(&reuseport_lock));
+	rcu_assign_pointer(sk->sk_reuseport_cb, NULL);
+
+	for (i = 0; i < reuse->num_socks; i++) {
+		if (reuse->socks[i] == sk) {
+			reuse->socks[i] = reuse->socks[reuse->num_socks - 1];
+			reuse->num_socks--;
+			if (reuse->num_socks == 0)
+				call_rcu(&reuse->rcu, reuseport_free_rcu);
+			break;
+		}
+	}
+	spin_unlock_bh(&reuseport_lock);
+}
+EXPORT_SYMBOL(reuseport_detach_sock);
+
+static struct sock *run_bpf(struct sock_reuseport *reuse, u16 socks,
+			    struct bpf_prog *prog, struct sk_buff *skb,
+			    int hdr_len)
+{
+	struct sk_buff *nskb = NULL;
+	u32 index;
+
+	if (skb_shared(skb)) {
+		nskb = skb_clone(skb, GFP_ATOMIC);
+		if (!nskb)
+			return NULL;
+		skb = nskb;
+	}
+
+	/* temporarily advance data past protocol header */
+	if (!pskb_pull(skb, hdr_len)) {
+		consume_skb(nskb);
+		return NULL;
+	}
+	index = bpf_prog_run_save_cb(prog, skb);
+	__skb_push(skb, hdr_len);
+
+	consume_skb(nskb);
+
+	if (index >= socks)
+		return NULL;
+
+	return reuse->socks[index];
+}
+
+/**
+ *  reuseport_select_sock - Select a socket from an SO_REUSEPORT group.
+ *  @sk: First socket in the group.
+ *  @hash: When no BPF filter is available, use this hash to select.
+ *  @skb: skb to run through BPF filter.
+ *  @hdr_len: BPF filter expects skb data pointer at payload data.  If
+ *    the skb does not yet point at the payload, this parameter represents
+ *    how far the pointer needs to advance to reach the payload.
+ *  Returns a socket that should receive the packet (or NULL on error).
+ */
+struct sock *reuseport_select_sock(struct sock *sk,
+				   u32 hash,
+				   struct sk_buff *skb,
+				   int hdr_len)
+{
+	struct sock_reuseport *reuse;
+	struct bpf_prog *prog;
+	struct sock *sk2 = NULL;
+	u16 socks;
+
+	rcu_read_lock();
+	reuse = rcu_dereference(sk->sk_reuseport_cb);
+
+	/* if memory allocation failed or add call is not yet complete */
+	if (!reuse)
+		goto out;
+
+	prog = rcu_dereference(reuse->prog);
+	socks = READ_ONCE(reuse->num_socks);
+	if (likely(socks)) {
+		/* paired with smp_wmb() in reuseport_add_sock() */
+		smp_rmb();
+
+		if (prog && skb)
+			sk2 = run_bpf(reuse, socks, prog, skb, hdr_len);
+		else
+			sk2 = reuse->socks[reciprocal_scale(hash, socks)];
+	}
+
+out:
+	rcu_read_unlock();
+	return sk2;
+}
+EXPORT_SYMBOL(reuseport_select_sock);
+
+struct bpf_prog *
+reuseport_attach_prog(struct sock *sk, struct bpf_prog *prog)
+{
+	struct sock_reuseport *reuse;
+	struct bpf_prog *old_prog;
+
+	spin_lock_bh(&reuseport_lock);
+	reuse = rcu_dereference_protected(sk->sk_reuseport_cb,
+					  lockdep_is_held(&reuseport_lock));
+	old_prog = rcu_dereference_protected(reuse->prog,
+					     lockdep_is_held(&reuseport_lock));
+	rcu_assign_pointer(reuse->prog, prog);
+	spin_unlock_bh(&reuseport_lock);
+
+	return old_prog;
+}
+EXPORT_SYMBOL(reuseport_attach_prog);

net/ipv4/udp.c

@@ -113,6 +113,7 @@
 #include <trace/events/skb.h>
 #include <net/busy_poll.h>
 #include "udp_impl.h"
+#include <net/sock_reuseport.h>
 
 struct udp_table udp_table __read_mostly;
 EXPORT_SYMBOL(udp_table);
@@ -137,7 +138,8 @@ static int udp_lib_lport_inuse(struct net *net, __u16 num,
 			       unsigned long *bitmap,
 			       struct sock *sk,
 			       int (*saddr_comp)(const struct sock *sk1,
-						 const struct sock *sk2),
+						 const struct sock *sk2,
+						 bool match_wildcard),
 			       unsigned int log)
 {
 	struct sock *sk2;
@@ -152,8 +154,9 @@ static int udp_lib_lport_inuse(struct net *net, __u16 num,
 		    (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if ||
 		     sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
 		    (!sk2->sk_reuseport || !sk->sk_reuseport ||
+		     rcu_access_pointer(sk->sk_reuseport_cb) ||
 		     !uid_eq(uid, sock_i_uid(sk2))) &&
-		    saddr_comp(sk, sk2)) {
+		    saddr_comp(sk, sk2, true)) {
 			if (!bitmap)
 				return 1;
 			__set_bit(udp_sk(sk2)->udp_port_hash >> log, bitmap);
@@ -170,7 +173,8 @@ static int udp_lib_lport_inuse2(struct net *net, __u16 num,
 				struct udp_hslot *hslot2,
 				struct sock *sk,
 				int (*saddr_comp)(const struct sock *sk1,
-						  const struct sock *sk2))
+						  const struct sock *sk2,
+						  bool match_wildcard))
 {
 	struct sock *sk2;
 	struct hlist_nulls_node *node;
@@ -186,8 +190,9 @@ static int udp_lib_lport_inuse2(struct net *net, __u16 num,
 		    (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if ||
 		     sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
 		    (!sk2->sk_reuseport || !sk->sk_reuseport ||
+		     rcu_access_pointer(sk->sk_reuseport_cb) ||
 		     !uid_eq(uid, sock_i_uid(sk2))) &&
-		    saddr_comp(sk, sk2)) {
+		    saddr_comp(sk, sk2, true)) {
 			res = 1;
 			break;
 		}
@@ -196,6 +201,35 @@ static int udp_lib_lport_inuse2(struct net *net, __u16 num,
 	return res;
 }
 
+static int udp_reuseport_add_sock(struct sock *sk, struct udp_hslot *hslot,
+				  int (*saddr_same)(const struct sock *sk1,
+						    const struct sock *sk2,
+						    bool match_wildcard))
+{
+	struct net *net = sock_net(sk);
+	struct hlist_nulls_node *node;
+	kuid_t uid = sock_i_uid(sk);
+	struct sock *sk2;
+
+	sk_nulls_for_each(sk2, node, &hslot->head) {
+		if (net_eq(sock_net(sk2), net) &&
+		    sk2 != sk &&
+		    sk2->sk_family == sk->sk_family &&
+		    ipv6_only_sock(sk2) == ipv6_only_sock(sk) &&
+		    (udp_sk(sk2)->udp_port_hash == udp_sk(sk)->udp_port_hash) &&
+		    (sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
+		    sk2->sk_reuseport && uid_eq(uid, sock_i_uid(sk2)) &&
+		    (*saddr_same)(sk, sk2, false)) {
+			return reuseport_add_sock(sk, sk2);
+		}
+	}
+
+	/* Initial allocation may have already happened via setsockopt */
+	if (!rcu_access_pointer(sk->sk_reuseport_cb))
+		return reuseport_alloc(sk);
+	return 0;
+}
+
 /**
  *  udp_lib_get_port  -  UDP/-Lite port lookup for IPv4 and IPv6
  *
@@ -207,7 +241,8 @@ static int udp_lib_lport_inuse2(struct net *net, __u16 num,
  */
 int udp_lib_get_port(struct sock *sk, unsigned short snum,
 		     int (*saddr_comp)(const struct sock *sk1,
-				       const struct sock *sk2),
+				       const struct sock *sk2,
+				       bool match_wildcard),
 		     unsigned int hash2_nulladdr)
 {
 	struct udp_hslot *hslot, *hslot2;
@@ -290,6 +325,14 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum,
 	udp_sk(sk)->udp_port_hash = snum;
 	udp_sk(sk)->udp_portaddr_hash ^= snum;
 	if (sk_unhashed(sk)) {
+		if (sk->sk_reuseport &&
+		    udp_reuseport_add_sock(sk, hslot, saddr_comp)) {
+			inet_sk(sk)->inet_num = 0;
+			udp_sk(sk)->udp_port_hash = 0;
+			udp_sk(sk)->udp_portaddr_hash ^= snum;
+			goto fail_unlock;
+		}
+
 		sk_nulls_add_node_rcu(sk, &hslot->head);
 		hslot->count++;
 		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
@@ -309,13 +352,22 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum,
 }
 EXPORT_SYMBOL(udp_lib_get_port);
 
-static int ipv4_rcv_saddr_equal(const struct sock *sk1, const struct sock *sk2)
+/* match_wildcard == true:  0.0.0.0 equals to any IPv4 addresses
+ * match_wildcard == false: addresses must be exactly the same, i.e.
+ *                          0.0.0.0 only equals to 0.0.0.0
+ */
+static int ipv4_rcv_saddr_equal(const struct sock *sk1, const struct sock *sk2,
+				bool match_wildcard)
 {
 	struct inet_sock *inet1 = inet_sk(sk1), *inet2 = inet_sk(sk2);
 
-	return 	(!ipv6_only_sock(sk2)  &&
-		 (!inet1->inet_rcv_saddr || !inet2->inet_rcv_saddr ||
-		   inet1->inet_rcv_saddr == inet2->inet_rcv_saddr));
+	if (!ipv6_only_sock(sk2)) {
+		if (inet1->inet_rcv_saddr == inet2->inet_rcv_saddr)
+			return 1;
+		if (!inet1->inet_rcv_saddr || !inet2->inet_rcv_saddr)
+			return match_wildcard;
+	}
+	return 0;
 }
 
 static u32 udp4_portaddr_hash(const struct net *net, __be32 saddr,
@@ -459,8 +511,14 @@ static struct sock *udp4_lib_lookup2(struct net *net,
 			badness = score;
 			reuseport = sk->sk_reuseport;
 			if (reuseport) {
+				struct sock *sk2;
 				hash = udp_ehashfn(net, daddr, hnum,
 						   saddr, sport);
+				sk2 = reuseport_select_sock(sk, hash, NULL, 0);
+				if (sk2) {
+					result = sk2;
+					goto found;
+				}
 				matches = 1;
 			}
 		} else if (score == badness && reuseport) {
@@ -478,6 +536,7 @@ static struct sock *udp4_lib_lookup2(struct net *net,
 	if (get_nulls_value(node) != slot2)
 		goto begin;
 	if (result) {
+found:
 		if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
 			result = NULL;
 		else if (unlikely(compute_score2(result, net, saddr, sport,
@@ -494,7 +553,7 @@ static struct sock *udp4_lib_lookup2(struct net *net,
  */
 struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
 		__be16 sport, __be32 daddr, __be16 dport,
-		int dif, struct udp_table *udptable)
+		int dif, struct udp_table *udptable, struct sk_buff *skb)
 {
 	struct sock *sk, *result;
 	struct hlist_nulls_node *node;
@@ -540,8 +599,15 @@ struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
 			badness = score;
 			reuseport = sk->sk_reuseport;
 			if (reuseport) {
+				struct sock *sk2;
 				hash = udp_ehashfn(net, daddr, hnum,
 						   saddr, sport);
+				sk2 = reuseport_select_sock(sk, hash, skb,
+							sizeof(struct udphdr));
+				if (sk2) {
+					result = sk2;
+					goto found;
+				}
 				matches = 1;
 			}
 		} else if (score == badness && reuseport) {
@@ -560,6 +626,7 @@ struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
 		goto begin;
 
 	if (result) {
+found:
 		if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
 			result = NULL;
 		else if (unlikely(compute_score(result, net, saddr, hnum, sport,
@@ -581,13 +648,14 @@ static inline struct sock *__udp4_lib_lookup_skb(struct sk_buff *skb,
 
 	return __udp4_lib_lookup(dev_net(skb_dst(skb)->dev), iph->saddr, sport,
 				 iph->daddr, dport, inet_iif(skb),
-				 udptable);
+				 udptable, skb);
 }
 
 struct sock *udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
 			     __be32 daddr, __be16 dport, int dif)
 {
-	return __udp4_lib_lookup(net, saddr, sport, daddr, dport, dif, &udp_table);
+	return __udp4_lib_lookup(net, saddr, sport, daddr, dport, dif,
+				 &udp_table, NULL);
 }
 EXPORT_SYMBOL_GPL(udp4_lib_lookup);
 
@@ -635,7 +703,8 @@ void __udp4_lib_err(struct sk_buff *skb, u32 info, struct udp_table *udptable)
 	struct net *net = dev_net(skb->dev);
 
 	sk = __udp4_lib_lookup(net, iph->daddr, uh->dest,
-			iph->saddr, uh->source, skb->dev->ifindex, udptable);
+			iph->saddr, uh->source, skb->dev->ifindex, udptable,
+			NULL);
 	if (!sk) {
 		ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 		return;	/* No socket for error */
@@ -1398,6 +1467,8 @@ void udp_lib_unhash(struct sock *sk)
 		hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
 
 		spin_lock_bh(&hslot->lock);
+		if (rcu_access_pointer(sk->sk_reuseport_cb))
+			reuseport_detach_sock(sk);
 		if (sk_nulls_del_node_init_rcu(sk)) {
 			hslot->count--;
 			inet_sk(sk)->inet_num = 0;
@@ -1425,12 +1496,17 @@ void udp_lib_rehash(struct sock *sk, u16 newhash)
 		hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
 		nhslot2 = udp_hashslot2(udptable, newhash);
 		udp_sk(sk)->udp_portaddr_hash = newhash;
-		if (hslot2 != nhslot2) {
+
+		if (hslot2 != nhslot2 ||
+		    rcu_access_pointer(sk->sk_reuseport_cb)) {
 			hslot = udp_hashslot(udptable, sock_net(sk),
 					     udp_sk(sk)->udp_port_hash);
 			/* we must lock primary chain too */
 			spin_lock_bh(&hslot->lock);
+			if (rcu_access_pointer(sk->sk_reuseport_cb))
+				reuseport_detach_sock(sk);
 
+			if (hslot2 != nhslot2) {
 				spin_lock(&hslot2->lock);
 				hlist_nulls_del_init_rcu(&udp_sk(sk)->udp_portaddr_node);
 				hslot2->count--;
@@ -1441,6 +1517,7 @@ void udp_lib_rehash(struct sock *sk, u16 newhash)
 							 &nhslot2->head);
 				nhslot2->count++;
 				spin_unlock(&nhslot2->lock);
+			}
 
 			spin_unlock_bh(&hslot->lock);
 		}

net/ipv4/udp_diag.c

@@ -44,7 +44,7 @@ static int udp_dump_one(struct udp_table *tbl, struct sk_buff *in_skb,
 		sk = __udp4_lib_lookup(net,
 				req->id.idiag_src[0], req->id.idiag_sport,
 				req->id.idiag_dst[0], req->id.idiag_dport,
-				req->id.idiag_if, tbl);
+				req->id.idiag_if, tbl, NULL);
 #if IS_ENABLED(CONFIG_IPV6)
 	else if (req->sdiag_family == AF_INET6)
 		sk = __udp6_lib_lookup(net,
@@ -52,7 +52,7 @@ static int udp_dump_one(struct udp_table *tbl, struct sk_buff *in_skb,
 				req->id.idiag_sport,
 				(struct in6_addr *)req->id.idiag_dst,
 				req->id.idiag_dport,
-				req->id.idiag_if, tbl);
+				req->id.idiag_if, tbl, NULL);
 #endif
 	else
 		goto out_nosk;

net/ipv6/inet6_connection_sock.c

@@ -51,12 +51,12 @@ int inet6_csk_bind_conflict(const struct sock *sk,
 			     (sk2->sk_state != TCP_TIME_WAIT &&
 			      !uid_eq(uid,
 				      sock_i_uid((struct sock *)sk2))))) {
-				if (ipv6_rcv_saddr_equal(sk, sk2))
+				if (ipv6_rcv_saddr_equal(sk, sk2, true))
 					break;
 			}
 			if (!relax && reuse && sk2->sk_reuse &&
 			    sk2->sk_state != TCP_LISTEN &&
-			    ipv6_rcv_saddr_equal(sk, sk2))
+			    ipv6_rcv_saddr_equal(sk, sk2, true))
 				break;
 		}
 	}

net/ipv6/udp.c

@@ -47,6 +47,7 @@
 #include <net/xfrm.h>
 #include <net/inet6_hashtables.h>
 #include <net/busy_poll.h>
+#include <net/sock_reuseport.h>
 
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
@@ -76,7 +77,14 @@ static u32 udp6_ehashfn(const struct net *net,
 			       udp_ipv6_hash_secret + net_hash_mix(net));
 }
 
-int ipv6_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2)
+/* match_wildcard == true:  IPV6_ADDR_ANY equals to any IPv6 addresses if IPv6
+ *                          only, and any IPv4 addresses if not IPv6 only
+ * match_wildcard == false: addresses must be exactly the same, i.e.
+ *                          IPV6_ADDR_ANY only equals to IPV6_ADDR_ANY,
+ *                          and 0.0.0.0 equals to 0.0.0.0 only
+ */
+int ipv6_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
+			 bool match_wildcard)
 {
 	const struct in6_addr *sk2_rcv_saddr6 = inet6_rcv_saddr(sk2);
 	int sk2_ipv6only = inet_v6_ipv6only(sk2);
@@ -84,16 +92,24 @@ int ipv6_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2)
 	int addr_type2 = sk2_rcv_saddr6 ? ipv6_addr_type(sk2_rcv_saddr6) : IPV6_ADDR_MAPPED;
 
 	/* if both are mapped, treat as IPv4 */
-	if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED)
-		return (!sk2_ipv6only &&
-			(!sk->sk_rcv_saddr || !sk2->sk_rcv_saddr ||
-			  sk->sk_rcv_saddr == sk2->sk_rcv_saddr));
+	if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED) {
+		if (!sk2_ipv6only) {
+			if (sk->sk_rcv_saddr == sk2->sk_rcv_saddr)
+				return 1;
+			if (!sk->sk_rcv_saddr || !sk2->sk_rcv_saddr)
+				return match_wildcard;
+		}
+		return 0;
+	}
 
-	if (addr_type2 == IPV6_ADDR_ANY &&
+	if (addr_type == IPV6_ADDR_ANY && addr_type2 == IPV6_ADDR_ANY)
+		return 1;
+
+	if (addr_type2 == IPV6_ADDR_ANY && match_wildcard &&
 	    !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED))
 		return 1;
 
-	if (addr_type == IPV6_ADDR_ANY &&
+	if (addr_type == IPV6_ADDR_ANY && match_wildcard &&
 	    !(ipv6_only_sock(sk) && addr_type2 == IPV6_ADDR_MAPPED))
 		return 1;
 
@@ -253,8 +269,14 @@ static struct sock *udp6_lib_lookup2(struct net *net,
 			badness = score;
 			reuseport = sk->sk_reuseport;
 			if (reuseport) {
+				struct sock *sk2;
 				hash = udp6_ehashfn(net, daddr, hnum,
 						    saddr, sport);
+				sk2 = reuseport_select_sock(sk, hash, NULL, 0);
+				if (sk2) {
+					result = sk2;
+					goto found;
+				}
 				matches = 1;
 			}
 		} else if (score == badness && reuseport) {
@@ -273,6 +295,7 @@ static struct sock *udp6_lib_lookup2(struct net *net,
 		goto begin;
 
 	if (result) {
+found:
 		if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
 			result = NULL;
 		else if (unlikely(compute_score2(result, net, saddr, sport,
@@ -287,7 +310,8 @@ static struct sock *udp6_lib_lookup2(struct net *net,
 struct sock *__udp6_lib_lookup(struct net *net,
 				      const struct in6_addr *saddr, __be16 sport,
 				      const struct in6_addr *daddr, __be16 dport,
-				      int dif, struct udp_table *udptable)
+				      int dif, struct udp_table *udptable,
+				      struct sk_buff *skb)
 {
 	struct sock *sk, *result;
 	struct hlist_nulls_node *node;
@@ -332,8 +356,15 @@ struct sock *__udp6_lib_lookup(struct net *net,
 			badness = score;
 			reuseport = sk->sk_reuseport;
 			if (reuseport) {
+				struct sock *sk2;
 				hash = udp6_ehashfn(net, daddr, hnum,
 						    saddr, sport);
+				sk2 = reuseport_select_sock(sk, hash, skb,
+							sizeof(struct udphdr));
+				if (sk2) {
+					result = sk2;
+					goto found;
+				}
 				matches = 1;
 			}
 		} else if (score == badness && reuseport) {
@@ -352,6 +383,7 @@ struct sock *__udp6_lib_lookup(struct net *net,
 		goto begin;
 
 	if (result) {
+found:
 		if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
 			result = NULL;
 		else if (unlikely(compute_score(result, net, hnum, saddr, sport,
@@ -377,13 +409,13 @@ static struct sock *__udp6_lib_lookup_skb(struct sk_buff *skb,
 		return sk;
 	return __udp6_lib_lookup(dev_net(skb_dst(skb)->dev), &iph->saddr, sport,
 				 &iph->daddr, dport, inet6_iif(skb),
-				 udptable);
+				 udptable, skb);
 }
 
 struct sock *udp6_lib_lookup(struct net *net, const struct in6_addr *saddr, __be16 sport,
 			     const struct in6_addr *daddr, __be16 dport, int dif)
 {
-	return __udp6_lib_lookup(net, saddr, sport, daddr, dport, dif, &udp_table);
+	return __udp6_lib_lookup(net, saddr, sport, daddr, dport, dif, &udp_table, NULL);
 }
 EXPORT_SYMBOL_GPL(udp6_lib_lookup);
 
@@ -549,8 +581,8 @@ void __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 	int err;
 	struct net *net = dev_net(skb->dev);
 
-	sk = __udp6_lib_lookup(net, daddr, uh->dest,
-			       saddr, uh->source, inet6_iif(skb), udptable);
+	sk = __udp6_lib_lookup(net, daddr, uh->dest, saddr, uh->source,
+			       inet6_iif(skb), udptable, skb);
 	if (!sk) {
 		ICMP6_INC_STATS_BH(net, __in6_dev_get(skb->dev),
 				   ICMP6_MIB_INERRORS);

tools/testing/selftests/net/.gitignore

 socket
 psock_fanout
 psock_tpacket
+reuseport_bpf

tools/testing/selftests/net/Makefile

@@ -4,7 +4,7 @@ CFLAGS = -Wall -O2 -g
 
 CFLAGS += -I../../../../usr/include/
 
-NET_PROGS = socket psock_fanout psock_tpacket
+NET_PROGS = socket psock_fanout psock_tpacket reuseport_bpf
 
 all: $(NET_PROGS)
 %: %.c