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

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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: Tanner Love <tannerlove@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Tanner Love 2020-11-06 13:07:40 -05:00 committed by Jakub Kicinski
parent a3ce2b109a
commit 9c661b0b85
3 changed files with 40 additions and 14 deletions
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12
include/uapi/linux/if_packet.h
View File

@ -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

37
net/packet/af_packet.c
View File

@ -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)
goto out;
if (!match) {
if (match) {
if (match->flags != flags)
goto out;
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:
{

5
net/packet/internal.h
View File

@ -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 {