// SPDX-License-Identifier: GPL-2.0-only
/*
* Generic netlink handshake service
*
* Author: Chuck Lever <[email protected]>
*
* Copyright (c) 2023, Oracle and/or its affiliates.
*/
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/mm.h>
#include <net/sock.h>
#include <net/genetlink.h>
#include <net/netns/generic.h>
#include <kunit/visibility.h>
#include <uapi/linux/handshake.h>
#include "handshake.h"
#include "genl.h"
#include <trace/events/handshake.h>
/**
* handshake_genl_notify - Notify handlers that a request is waiting
* @net: target network namespace
* @proto: handshake protocol
* @flags: memory allocation control flags
*
* Returns zero on success or a negative errno if notification failed.
*/
int handshake_genl_notify(struct net *net, const struct handshake_proto *proto,
gfp_t flags)
{
struct sk_buff *msg;
void *hdr;
/* Disable notifications during unit testing */
if (!test_bit(HANDSHAKE_F_PROTO_NOTIFY, &proto->hp_flags))
return 0;
if (!genl_has_listeners(&handshake_nl_family, net,
proto->hp_handler_class))
return -ESRCH;
msg = genlmsg_new(GENLMSG_DEFAULT_SIZE, flags);
if (!msg)
return -ENOMEM;
hdr = genlmsg_put(msg, 0, 0, &handshake_nl_family, 0,
HANDSHAKE_CMD_READY);
if (!hdr)
goto out_free;
if (nla_put_u32(msg, HANDSHAKE_A_ACCEPT_HANDLER_CLASS,
proto->hp_handler_class) < 0) {
genlmsg_cancel(msg, hdr);
goto out_free;
}
genlmsg_end(msg, hdr);
return genlmsg_multicast_netns(&handshake_nl_family, net, msg,
0, proto->hp_handler_class, flags);
out_free:
nlmsg_free(msg);
return -EMSGSIZE;
}
/**
* handshake_genl_put - Create a generic netlink message header
* @msg: buffer in which to create the header
* @info: generic netlink message context
*
* Returns a ready-to-use header, or NULL.
*/
struct nlmsghdr *handshake_genl_put(struct sk_buff *msg,
struct genl_info *info)
{
return genlmsg_put(msg, info->snd_portid, info->snd_seq,
&handshake_nl_family, 0, info->genlhdr->cmd);
}
EXPORT_SYMBOL(handshake_genl_put);
int handshake_nl_accept_doit(struct sk_buff *skb, struct genl_info *info)
{
struct net *net = sock_net(skb->sk);
struct handshake_net *hn = handshake_pernet(net);
struct handshake_req *req = NULL;
struct socket *sock;
int class, fd, err;
err = -EOPNOTSUPP;
if (!hn)
goto out_status;
err = -EINVAL;
if (GENL_REQ_ATTR_CHECK(info, HANDSHAKE_A_ACCEPT_HANDLER_CLASS))
goto out_status;
class = nla_get_u32(info->attrs[HANDSHAKE_A_ACCEPT_HANDLER_CLASS]);
err = -EAGAIN;
req = handshake_req_next(hn, class);
if (!req)
goto out_status;
sock = req->hr_sk->sk_socket;
fd = get_unused_fd_flags(O_CLOEXEC);
if (fd < 0) {
err = fd;
goto out_complete;
}
err = req->hr_proto->hp_accept(req, info, fd);
if (err) {
put_unused_fd(fd);
goto out_complete;
}
fd_install(fd, get_file(sock->file));
trace_handshake_cmd_accept(net, req, req->hr_sk, fd);
return 0;
out_complete:
handshake_complete(req, -EIO, NULL);
out_status:
trace_handshake_cmd_accept_err(net, req, NULL, err);
return err;
}
int handshake_nl_done_doit(struct sk_buff *skb, struct genl_info *info)
{
struct net *net = sock_net(skb->sk);
struct handshake_req *req;
struct socket *sock;
int fd, status, err;
if (GENL_REQ_ATTR_CHECK(info, HANDSHAKE_A_DONE_SOCKFD))
return -EINVAL;
fd = nla_get_s32(info->attrs[HANDSHAKE_A_DONE_SOCKFD]);
sock = sockfd_lookup(fd, &err);
if (!sock)
return err;
req = handshake_req_hash_lookup(sock->sk);
if (!req) {
err = -EBUSY;
trace_handshake_cmd_done_err(net, req, sock->sk, err);
sockfd_put(sock);
return err;
}
trace_handshake_cmd_done(net, req, sock->sk, fd);
status = -EIO;
if (info->attrs[HANDSHAKE_A_DONE_STATUS])
status = nla_get_u32(info->attrs[HANDSHAKE_A_DONE_STATUS]);
handshake_complete(req, status, info);
sockfd_put(sock);
return 0;
}
static unsigned int handshake_net_id;
static int __net_init handshake_net_init(struct net *net)
{
struct handshake_net *hn = net_generic(net, handshake_net_id);
unsigned long tmp;
struct sysinfo si;
/*
* Arbitrary limit to prevent handshakes that do not make
* progress from clogging up the system. The cap scales up
* with the amount of physical memory on the system.
*/
si_meminfo(&si);
tmp = si.totalram / (25 * si.mem_unit);
hn->hn_pending_max = clamp(tmp, 3UL, 50UL);
spin_lock_init(&hn->hn_lock);
hn->hn_pending = 0;
hn->hn_flags = 0;
INIT_LIST_HEAD(&hn->hn_requests);
return 0;
}
static void __net_exit handshake_net_exit(struct net *net)
{
struct handshake_net *hn = net_generic(net, handshake_net_id);
struct handshake_req *req;
LIST_HEAD(requests);
/*
* Drain the net's pending list. Requests that have been
* accepted and are in progress will be destroyed when
* the socket is closed.
*/
spin_lock(&hn->hn_lock);
set_bit(HANDSHAKE_F_NET_DRAINING, &hn->hn_flags);
list_splice_init(&requests, &hn->hn_requests);
spin_unlock(&hn->hn_lock);
while (!list_empty(&requests)) {
req = list_first_entry(&requests, struct handshake_req, hr_list);
list_del(&req->hr_list);
/*
* Requests on this list have not yet been
* accepted, so they do not have an fd to put.
*/
handshake_complete(req, -ETIMEDOUT, NULL);
}
}
static struct pernet_operations handshake_genl_net_ops = {
.init = handshake_net_init,
.exit = handshake_net_exit,
.id = &handshake_net_id,
.size = sizeof(struct handshake_net),
};
/**
* handshake_pernet - Get the handshake private per-net structure
* @net: network namespace
*
* Returns a pointer to the net's private per-net structure for the
* handshake module, or NULL if handshake_init() failed.
*/
struct handshake_net *handshake_pernet(struct net *net)
{
return handshake_net_id ?
net_generic(net, handshake_net_id) : NULL;
}
EXPORT_SYMBOL_IF_KUNIT(handshake_pernet);
static int __init handshake_init(void)
{
int ret;
ret = handshake_req_hash_init();
if (ret) {
pr_warn("handshake: hash initialization failed (%d)\n", ret);
return ret;
}
ret = genl_register_family(&handshake_nl_family);
if (ret) {
pr_warn("handshake: netlink registration failed (%d)\n", ret);
handshake_req_hash_destroy();
return ret;
}
/*
* ORDER: register_pernet_subsys must be done last.
*
* If initialization does not make it past pernet_subsys
* registration, then handshake_net_id will remain 0. That
* shunts the handshake consumer API to return ENOTSUPP
* to prevent it from dereferencing something that hasn't
* been allocated.
*/
ret = register_pernet_subsys(&handshake_genl_net_ops);
if (ret) {
pr_warn("handshake: pernet registration failed (%d)\n", ret);
genl_unregister_family(&handshake_nl_family);
handshake_req_hash_destroy();
}
return ret;
}
static void __exit handshake_exit(void)
{
unregister_pernet_subsys(&handshake_genl_net_ops);
handshake_net_id = 0;
handshake_req_hash_destroy();
genl_unregister_family(&handshake_nl_family);
}
module_init(handshake_init);
module_exit(handshake_exit);