linux/net/core/sock_diag.c
Eric Dumazet b4cb4a1391 net: use unrcu_pointer() helper
Toke mentioned unrcu_pointer() existence, allowing
to remove some of the ugly casts we have when using
xchg() for rcu protected pointers.

Also make inet_rcv_compat const.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Toke Høiland-Jørgensen <toke@redhat.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20240604111603.45871-1-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2024-06-06 11:52:52 +02:00

358 lines
8.0 KiB
C

/* License: GPL */
#include <linux/filter.h>
#include <linux/mutex.h>
#include <linux/socket.h>
#include <linux/skbuff.h>
#include <net/netlink.h>
#include <net/net_namespace.h>
#include <linux/module.h>
#include <net/sock.h>
#include <linux/kernel.h>
#include <linux/tcp.h>
#include <linux/workqueue.h>
#include <linux/nospec.h>
#include <linux/cookie.h>
#include <linux/inet_diag.h>
#include <linux/sock_diag.h>
static const struct sock_diag_handler __rcu *sock_diag_handlers[AF_MAX];
static const struct sock_diag_inet_compat __rcu *inet_rcv_compat;
static struct workqueue_struct *broadcast_wq;
DEFINE_COOKIE(sock_cookie);
u64 __sock_gen_cookie(struct sock *sk)
{
u64 res = atomic64_read(&sk->sk_cookie);
if (!res) {
u64 new = gen_cookie_next(&sock_cookie);
atomic64_cmpxchg(&sk->sk_cookie, res, new);
/* Another thread might have changed sk_cookie before us. */
res = atomic64_read(&sk->sk_cookie);
}
return res;
}
int sock_diag_check_cookie(struct sock *sk, const __u32 *cookie)
{
u64 res;
if (cookie[0] == INET_DIAG_NOCOOKIE && cookie[1] == INET_DIAG_NOCOOKIE)
return 0;
res = sock_gen_cookie(sk);
if ((u32)res != cookie[0] || (u32)(res >> 32) != cookie[1])
return -ESTALE;
return 0;
}
EXPORT_SYMBOL_GPL(sock_diag_check_cookie);
void sock_diag_save_cookie(struct sock *sk, __u32 *cookie)
{
u64 res = sock_gen_cookie(sk);
cookie[0] = (u32)res;
cookie[1] = (u32)(res >> 32);
}
EXPORT_SYMBOL_GPL(sock_diag_save_cookie);
int sock_diag_put_meminfo(struct sock *sk, struct sk_buff *skb, int attrtype)
{
u32 mem[SK_MEMINFO_VARS];
sk_get_meminfo(sk, mem);
return nla_put(skb, attrtype, sizeof(mem), &mem);
}
EXPORT_SYMBOL_GPL(sock_diag_put_meminfo);
int sock_diag_put_filterinfo(bool may_report_filterinfo, struct sock *sk,
struct sk_buff *skb, int attrtype)
{
struct sock_fprog_kern *fprog;
struct sk_filter *filter;
struct nlattr *attr;
unsigned int flen;
int err = 0;
if (!may_report_filterinfo) {
nla_reserve(skb, attrtype, 0);
return 0;
}
rcu_read_lock();
filter = rcu_dereference(sk->sk_filter);
if (!filter)
goto out;
fprog = filter->prog->orig_prog;
if (!fprog)
goto out;
flen = bpf_classic_proglen(fprog);
attr = nla_reserve(skb, attrtype, flen);
if (attr == NULL) {
err = -EMSGSIZE;
goto out;
}
memcpy(nla_data(attr), fprog->filter, flen);
out:
rcu_read_unlock();
return err;
}
EXPORT_SYMBOL(sock_diag_put_filterinfo);
struct broadcast_sk {
struct sock *sk;
struct work_struct work;
};
static size_t sock_diag_nlmsg_size(void)
{
return NLMSG_ALIGN(sizeof(struct inet_diag_msg)
+ nla_total_size(sizeof(u8)) /* INET_DIAG_PROTOCOL */
+ nla_total_size_64bit(sizeof(struct tcp_info))); /* INET_DIAG_INFO */
}
static const struct sock_diag_handler *sock_diag_lock_handler(int family)
{
const struct sock_diag_handler *handler;
rcu_read_lock();
handler = rcu_dereference(sock_diag_handlers[family]);
if (handler && !try_module_get(handler->owner))
handler = NULL;
rcu_read_unlock();
return handler;
}
static void sock_diag_unlock_handler(const struct sock_diag_handler *handler)
{
module_put(handler->owner);
}
static void sock_diag_broadcast_destroy_work(struct work_struct *work)
{
struct broadcast_sk *bsk =
container_of(work, struct broadcast_sk, work);
struct sock *sk = bsk->sk;
const struct sock_diag_handler *hndl;
struct sk_buff *skb;
const enum sknetlink_groups group = sock_diag_destroy_group(sk);
int err = -1;
WARN_ON(group == SKNLGRP_NONE);
skb = nlmsg_new(sock_diag_nlmsg_size(), GFP_KERNEL);
if (!skb)
goto out;
hndl = sock_diag_lock_handler(sk->sk_family);
if (hndl) {
if (hndl->get_info)
err = hndl->get_info(skb, sk);
sock_diag_unlock_handler(hndl);
}
if (!err)
nlmsg_multicast(sock_net(sk)->diag_nlsk, skb, 0, group,
GFP_KERNEL);
else
kfree_skb(skb);
out:
sk_destruct(sk);
kfree(bsk);
}
void sock_diag_broadcast_destroy(struct sock *sk)
{
/* Note, this function is often called from an interrupt context. */
struct broadcast_sk *bsk =
kmalloc(sizeof(struct broadcast_sk), GFP_ATOMIC);
if (!bsk)
return sk_destruct(sk);
bsk->sk = sk;
INIT_WORK(&bsk->work, sock_diag_broadcast_destroy_work);
queue_work(broadcast_wq, &bsk->work);
}
void sock_diag_register_inet_compat(const struct sock_diag_inet_compat *ptr)
{
xchg(&inet_rcv_compat, RCU_INITIALIZER(ptr));
}
EXPORT_SYMBOL_GPL(sock_diag_register_inet_compat);
void sock_diag_unregister_inet_compat(const struct sock_diag_inet_compat *ptr)
{
const struct sock_diag_inet_compat *old;
old = unrcu_pointer(xchg(&inet_rcv_compat, NULL));
WARN_ON_ONCE(old != ptr);
}
EXPORT_SYMBOL_GPL(sock_diag_unregister_inet_compat);
int sock_diag_register(const struct sock_diag_handler *hndl)
{
int family = hndl->family;
if (family >= AF_MAX)
return -EINVAL;
return !cmpxchg((const struct sock_diag_handler **)
&sock_diag_handlers[family],
NULL, hndl) ? 0 : -EBUSY;
}
EXPORT_SYMBOL_GPL(sock_diag_register);
void sock_diag_unregister(const struct sock_diag_handler *hndl)
{
int family = hndl->family;
if (family >= AF_MAX)
return;
xchg((const struct sock_diag_handler **)&sock_diag_handlers[family],
NULL);
}
EXPORT_SYMBOL_GPL(sock_diag_unregister);
static int __sock_diag_cmd(struct sk_buff *skb, struct nlmsghdr *nlh)
{
int err;
struct sock_diag_req *req = nlmsg_data(nlh);
const struct sock_diag_handler *hndl;
if (nlmsg_len(nlh) < sizeof(*req))
return -EINVAL;
if (req->sdiag_family >= AF_MAX)
return -EINVAL;
req->sdiag_family = array_index_nospec(req->sdiag_family, AF_MAX);
if (!rcu_access_pointer(sock_diag_handlers[req->sdiag_family]))
sock_load_diag_module(req->sdiag_family, 0);
hndl = sock_diag_lock_handler(req->sdiag_family);
if (hndl == NULL)
return -ENOENT;
if (nlh->nlmsg_type == SOCK_DIAG_BY_FAMILY)
err = hndl->dump(skb, nlh);
else if (nlh->nlmsg_type == SOCK_DESTROY && hndl->destroy)
err = hndl->destroy(skb, nlh);
else
err = -EOPNOTSUPP;
sock_diag_unlock_handler(hndl);
return err;
}
static int sock_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack)
{
const struct sock_diag_inet_compat *ptr;
int ret;
switch (nlh->nlmsg_type) {
case TCPDIAG_GETSOCK:
case DCCPDIAG_GETSOCK:
if (!rcu_access_pointer(inet_rcv_compat))
sock_load_diag_module(AF_INET, 0);
rcu_read_lock();
ptr = rcu_dereference(inet_rcv_compat);
if (ptr && !try_module_get(ptr->owner))
ptr = NULL;
rcu_read_unlock();
ret = -EOPNOTSUPP;
if (ptr) {
ret = ptr->fn(skb, nlh);
module_put(ptr->owner);
}
return ret;
case SOCK_DIAG_BY_FAMILY:
case SOCK_DESTROY:
return __sock_diag_cmd(skb, nlh);
default:
return -EINVAL;
}
}
static void sock_diag_rcv(struct sk_buff *skb)
{
netlink_rcv_skb(skb, &sock_diag_rcv_msg);
}
static int sock_diag_bind(struct net *net, int group)
{
switch (group) {
case SKNLGRP_INET_TCP_DESTROY:
case SKNLGRP_INET_UDP_DESTROY:
if (!rcu_access_pointer(sock_diag_handlers[AF_INET]))
sock_load_diag_module(AF_INET, 0);
break;
case SKNLGRP_INET6_TCP_DESTROY:
case SKNLGRP_INET6_UDP_DESTROY:
if (!rcu_access_pointer(sock_diag_handlers[AF_INET6]))
sock_load_diag_module(AF_INET6, 0);
break;
}
return 0;
}
int sock_diag_destroy(struct sock *sk, int err)
{
if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
return -EPERM;
if (!sk->sk_prot->diag_destroy)
return -EOPNOTSUPP;
return sk->sk_prot->diag_destroy(sk, err);
}
EXPORT_SYMBOL_GPL(sock_diag_destroy);
static int __net_init diag_net_init(struct net *net)
{
struct netlink_kernel_cfg cfg = {
.groups = SKNLGRP_MAX,
.input = sock_diag_rcv,
.bind = sock_diag_bind,
.flags = NL_CFG_F_NONROOT_RECV,
};
net->diag_nlsk = netlink_kernel_create(net, NETLINK_SOCK_DIAG, &cfg);
return net->diag_nlsk == NULL ? -ENOMEM : 0;
}
static void __net_exit diag_net_exit(struct net *net)
{
netlink_kernel_release(net->diag_nlsk);
net->diag_nlsk = NULL;
}
static struct pernet_operations diag_net_ops = {
.init = diag_net_init,
.exit = diag_net_exit,
};
static int __init sock_diag_init(void)
{
broadcast_wq = alloc_workqueue("sock_diag_events", 0, 0);
BUG_ON(!broadcast_wq);
return register_pernet_subsys(&diag_net_ops);
}
device_initcall(sock_diag_init);