Commit 9c661b0b authored by Tanner Love's avatar Tanner Love Committed by Jakub Kicinski
Browse files

net/packet: make packet_fanout.arr size configurable up to 64K 



One use case of PACKET_FANOUT is lockless reception with one socket
per CPU. 256 is a practical limit on increasingly many machines.

Increase PACKET_FANOUT_MAX to 64K. Expand setsockopt PACKET_FANOUT to
take an extra argument max_num_members. Also explicitly define a
fanout_args struct, instead of implicitly casting to an integer. This
documents the API and simplifies the control flow.

If max_num_members is not specified or is set to 0, then 256 is used,
same as before.

Signed-off-by: default avatarTanner Love <tannerlove@google.com>
Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent a3ce2b10

include/uapi/linux/if_packet.h

+12 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
#ifndef __LINUX_IF_PACKET_H

#define __LINUX_IF_PACKET_H



#include <asm/byteorder.h>

#include <linux/types.h>



struct sockaddr_pkt {
@@ -296,6 +297,17 @@ struct packet_mreq { 
	unsigned char	mr_address[8];

};



struct fanout_args {

#if defined(__LITTLE_ENDIAN_BITFIELD)

	__u16		id;

	__u16		type_flags;

#else

	__u16		type_flags;

	__u16		id;

#endif

	__u32		max_num_members;

};



#define PACKET_MR_MULTICAST	0

#define PACKET_MR_PROMISC	1

#define PACKET_MR_ALLMULTI	2

net/packet/af_packet.c

+25 −12
Original line number Diff line number Diff line
@@ -1636,13 +1636,15 @@ static bool fanout_find_new_id(struct sock *sk, u16 *new_id) 
	return false;

}



static int fanout_add(struct sock *sk, u16 id, u16 type_flags)

static int fanout_add(struct sock *sk, struct fanout_args *args)

{

	struct packet_rollover *rollover = NULL;

	struct packet_sock *po = pkt_sk(sk);

	u16 type_flags = args->type_flags;

	struct packet_fanout *f, *match;

	u8 type = type_flags & 0xff;

	u8 flags = type_flags >> 8;

	u16 id = args->id;

	int err;



	switch (type) {
@@ -1700,11 +1702,21 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags) 
		}

	}

	err = -EINVAL;

	if (match && match->flags != flags)

	if (match) {

		if (match->flags != flags)

			goto out;

	if (!match) {

		if (args->max_num_members &&

		    args->max_num_members != match->max_num_members)

			goto out;

	} else {

		if (args->max_num_members > PACKET_FANOUT_MAX)

			goto out;

		if (!args->max_num_members)

			/* legacy PACKET_FANOUT_MAX */

			args->max_num_members = 256;

		err = -ENOMEM;

		match = kzalloc(sizeof(*match), GFP_KERNEL);

		match = kvzalloc(struct_size(match, arr, args->max_num_members),

				 GFP_KERNEL);

		if (!match)

			goto out;

		write_pnet(&match->net, sock_net(sk));
@@ -1720,6 +1732,7 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags) 
		match->prot_hook.func = packet_rcv_fanout;

		match->prot_hook.af_packet_priv = match;

		match->prot_hook.id_match = match_fanout_group;

		match->max_num_members = args->max_num_members;

		list_add(&match->list, &fanout_list);

	}

	err = -EINVAL;
@@ -1730,7 +1743,7 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags) 
	    match->prot_hook.type == po->prot_hook.type &&

	    match->prot_hook.dev == po->prot_hook.dev) {

		err = -ENOSPC;

		if (refcount_read(&match->sk_ref) < PACKET_FANOUT_MAX) {

		if (refcount_read(&match->sk_ref) < match->max_num_members) {

			__dev_remove_pack(&po->prot_hook);

			po->fanout = match;

			po->rollover = rollover;
@@ -1744,7 +1757,7 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags) 


	if (err && !refcount_read(&match->sk_ref)) {

		list_del(&match->list);

		kfree(match);

		kvfree(match);

	}



out:
@@ -3075,7 +3088,7 @@ static int packet_release(struct socket *sock) 
	kfree(po->rollover);

	if (f) {

		fanout_release_data(f);

		kfree(f);

		kvfree(f);

	}

	/*

	 *	Now the socket is dead. No more input will appear.
@@ -3866,14 +3879,14 @@ packet_setsockopt(struct socket *sock, int level, int optname, sockptr_t optval, 
	}

	case PACKET_FANOUT:

	{

		int val;

		struct fanout_args args = { 0 };



		if (optlen != sizeof(val))

		if (optlen != sizeof(int) && optlen != sizeof(args))

			return -EINVAL;

		if (copy_from_sockptr(&val, optval, sizeof(val)))

		if (copy_from_sockptr(&args, optval, optlen))

			return -EFAULT;



		return fanout_add(sk, val & 0xffff, val >> 16);

		return fanout_add(sk, &args);

	}

	case PACKET_FANOUT_DATA:

	{

net/packet/internal.h

+3 −2
Original line number Diff line number Diff line
@@ -77,11 +77,12 @@ struct packet_ring_buffer { 
};



extern struct mutex fanout_mutex;

#define PACKET_FANOUT_MAX	256

#define PACKET_FANOUT_MAX	(1 << 16)



struct packet_fanout {

	possible_net_t		net;

	unsigned int		num_members;

	u32			max_num_members;

	u16			id;

	u8			type;

	u8			flags;
@@ -90,10 +91,10 @@ struct packet_fanout { 
		struct bpf_prog __rcu	*bpf_prog;

	};

	struct list_head	list;

	struct sock		*arr[PACKET_FANOUT_MAX];

	spinlock_t		lock;

	refcount_t		sk_ref;

	struct packet_type	prot_hook ____cacheline_aligned_in_smp;

	struct sock		*arr[];

};



struct packet_rollover {

CRA Git | Maintained and supported by SUSTech CRA and CCSE