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linux/net/unix/diag.c
Kuniyuki Iwashima c4da4661d9 af_unix: Remove U_LOCK_DIAG. 
sk_diag_dump_icons() acquires embryo's lock by unix_state_lock_nested()
to fetch its peer.

The embryo's ->peer is set to NULL only when its parent listener is
close()d.  Then, unix_release_sock() is called for each embryo after
unlinking skb by skb_dequeue().

In sk_diag_dump_icons(), we hold the parent's recvq lock, so we need
not acquire unix_state_lock_nested(), and peer is always non-NULL.

Let's remove unnecessary unix_state_lock_nested() and non-NULL test
for peer.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2024-06-25 11:10:18 +02:00

323 lines
7.2 KiB
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// SPDX-License-Identifier: GPL-2.0-only
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/sock_diag.h>
#include <linux/unix_diag.h>
#include <linux/skbuff.h>
#include <linux/module.h>
#include <linux/uidgid.h>
#include <net/netlink.h>
#include <net/af_unix.h>
#include <net/tcp_states.h>
#include <net/sock.h>
static int sk_diag_dump_name(struct sock *sk, struct sk_buff *nlskb)
{
/* might or might not have a hash table lock */
struct unix_address *addr = smp_load_acquire(&unix_sk(sk)->addr);
if (!addr)
return 0;
return nla_put(nlskb, UNIX_DIAG_NAME,
addr->len - offsetof(struct sockaddr_un, sun_path),
addr->name->sun_path);
}
static int sk_diag_dump_vfs(struct sock *sk, struct sk_buff *nlskb)
{
struct dentry *dentry = unix_sk(sk)->path.dentry;
if (dentry) {
struct unix_diag_vfs uv = {
.udiag_vfs_ino = d_backing_inode(dentry)->i_ino,
.udiag_vfs_dev = dentry->d_sb->s_dev,
};
return nla_put(nlskb, UNIX_DIAG_VFS, sizeof(uv), &uv);
}
return 0;
}
static int sk_diag_dump_peer(struct sock *sk, struct sk_buff *nlskb)
{
struct sock *peer;
int ino;
peer = unix_peer_get(sk);
if (peer) {
ino = sock_i_ino(peer);
sock_put(peer);
return nla_put_u32(nlskb, UNIX_DIAG_PEER, ino);
}
return 0;
}
static int sk_diag_dump_icons(struct sock *sk, struct sk_buff *nlskb)
{
struct sk_buff *skb;
struct nlattr *attr;
u32 *buf;
int i;
if (READ_ONCE(sk->sk_state) == TCP_LISTEN) {
spin_lock(&sk->sk_receive_queue.lock);
attr = nla_reserve(nlskb, UNIX_DIAG_ICONS,
sk->sk_receive_queue.qlen * sizeof(u32));
if (!attr)
goto errout;
buf = nla_data(attr);
i = 0;
skb_queue_walk(&sk->sk_receive_queue, skb)
buf[i++] = sock_i_ino(unix_peer(skb->sk));
spin_unlock(&sk->sk_receive_queue.lock);
}
return 0;
errout:
spin_unlock(&sk->sk_receive_queue.lock);
return -EMSGSIZE;
}
static int sk_diag_show_rqlen(struct sock *sk, struct sk_buff *nlskb)
{
struct unix_diag_rqlen rql;
if (READ_ONCE(sk->sk_state) == TCP_LISTEN) {
rql.udiag_rqueue = skb_queue_len_lockless(&sk->sk_receive_queue);
rql.udiag_wqueue = sk->sk_max_ack_backlog;
} else {
rql.udiag_rqueue = (u32) unix_inq_len(sk);
rql.udiag_wqueue = (u32) unix_outq_len(sk);
}
return nla_put(nlskb, UNIX_DIAG_RQLEN, sizeof(rql), &rql);
}
static int sk_diag_dump_uid(struct sock *sk, struct sk_buff *nlskb,
struct user_namespace *user_ns)
{
uid_t uid = from_kuid_munged(user_ns, sock_i_uid(sk));
return nla_put(nlskb, UNIX_DIAG_UID, sizeof(uid_t), &uid);
}
static int sk_diag_fill(struct sock *sk, struct sk_buff *skb, struct unix_diag_req *req,
struct user_namespace *user_ns,
u32 portid, u32 seq, u32 flags, int sk_ino)
{
struct nlmsghdr *nlh;
struct unix_diag_msg *rep;
nlh = nlmsg_put(skb, portid, seq, SOCK_DIAG_BY_FAMILY, sizeof(*rep),
flags);
if (!nlh)
return -EMSGSIZE;
rep = nlmsg_data(nlh);
rep->udiag_family = AF_UNIX;
rep->udiag_type = sk->sk_type;
rep->udiag_state = READ_ONCE(sk->sk_state);
rep->pad = 0;
rep->udiag_ino = sk_ino;
sock_diag_save_cookie(sk, rep->udiag_cookie);
if ((req->udiag_show & UDIAG_SHOW_NAME) &&
sk_diag_dump_name(sk, skb))
goto out_nlmsg_trim;
if ((req->udiag_show & UDIAG_SHOW_VFS) &&
sk_diag_dump_vfs(sk, skb))
goto out_nlmsg_trim;
if ((req->udiag_show & UDIAG_SHOW_PEER) &&
sk_diag_dump_peer(sk, skb))
goto out_nlmsg_trim;
if ((req->udiag_show & UDIAG_SHOW_ICONS) &&
sk_diag_dump_icons(sk, skb))
goto out_nlmsg_trim;
if ((req->udiag_show & UDIAG_SHOW_RQLEN) &&
sk_diag_show_rqlen(sk, skb))
goto out_nlmsg_trim;
if ((req->udiag_show & UDIAG_SHOW_MEMINFO) &&
sock_diag_put_meminfo(sk, skb, UNIX_DIAG_MEMINFO))
goto out_nlmsg_trim;
if (nla_put_u8(skb, UNIX_DIAG_SHUTDOWN, READ_ONCE(sk->sk_shutdown)))
goto out_nlmsg_trim;
if ((req->udiag_show & UDIAG_SHOW_UID) &&
sk_diag_dump_uid(sk, skb, user_ns))
goto out_nlmsg_trim;
nlmsg_end(skb, nlh);
return 0;
out_nlmsg_trim:
nlmsg_cancel(skb, nlh);
return -EMSGSIZE;
}
static int unix_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
struct net *net = sock_net(skb->sk);
int num, s_num, slot, s_slot;
struct unix_diag_req *req;
req = nlmsg_data(cb->nlh);
s_slot = cb->args[0];
num = s_num = cb->args[1];
for (slot = s_slot; slot < UNIX_HASH_SIZE; s_num = 0, slot++) {
struct sock *sk;
num = 0;
spin_lock(&net->unx.table.locks[slot]);
sk_for_each(sk, &net->unx.table.buckets[slot]) {
int sk_ino;
if (num < s_num)
goto next;
if (!(req->udiag_states & (1 << READ_ONCE(sk->sk_state))))
goto next;
sk_ino = sock_i_ino(sk);
if (!sk_ino)
goto next;
if (sk_diag_fill(sk, skb, req, sk_user_ns(skb->sk),
NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq,
NLM_F_MULTI, sk_ino) < 0) {
spin_unlock(&net->unx.table.locks[slot]);
goto done;
}
next:
num++;
}
spin_unlock(&net->unx.table.locks[slot]);
}
done:
cb->args[0] = slot;
cb->args[1] = num;
return skb->len;
}
static struct sock *unix_lookup_by_ino(struct net *net, unsigned int ino)
{
struct sock *sk;
int i;
for (i = 0; i < UNIX_HASH_SIZE; i++) {
spin_lock(&net->unx.table.locks[i]);
sk_for_each(sk, &net->unx.table.buckets[i]) {
if (ino == sock_i_ino(sk)) {
sock_hold(sk);
spin_unlock(&net->unx.table.locks[i]);
return sk;
}
}
spin_unlock(&net->unx.table.locks[i]);
}
return NULL;
}
static int unix_diag_get_exact(struct sk_buff *in_skb,
const struct nlmsghdr *nlh,
struct unix_diag_req *req)
{
struct net *net = sock_net(in_skb->sk);
unsigned int extra_len;
struct sk_buff *rep;
struct sock *sk;
int err;
err = -EINVAL;
if (req->udiag_ino == 0)
goto out_nosk;
sk = unix_lookup_by_ino(net, req->udiag_ino);
err = -ENOENT;
if (sk == NULL)
goto out_nosk;
err = sock_diag_check_cookie(sk, req->udiag_cookie);
if (err)
goto out;
extra_len = 256;
again:
err = -ENOMEM;
rep = nlmsg_new(sizeof(struct unix_diag_msg) + extra_len, GFP_KERNEL);
if (!rep)
goto out;
err = sk_diag_fill(sk, rep, req, sk_user_ns(NETLINK_CB(in_skb).sk),
NETLINK_CB(in_skb).portid,
nlh->nlmsg_seq, 0, req->udiag_ino);
if (err < 0) {
nlmsg_free(rep);
extra_len += 256;
if (extra_len >= PAGE_SIZE)
goto out;
goto again;
}
err = nlmsg_unicast(net->diag_nlsk, rep, NETLINK_CB(in_skb).portid);
out:
if (sk)
sock_put(sk);
out_nosk:
return err;
}
static int unix_diag_handler_dump(struct sk_buff *skb, struct nlmsghdr *h)
{
int hdrlen = sizeof(struct unix_diag_req);
if (nlmsg_len(h) < hdrlen)
return -EINVAL;
if (h->nlmsg_flags & NLM_F_DUMP) {
struct netlink_dump_control c = {
.dump = unix_diag_dump,
};
return netlink_dump_start(sock_net(skb->sk)->diag_nlsk, skb, h, &c);
} else
return unix_diag_get_exact(skb, h, nlmsg_data(h));
}
static const struct sock_diag_handler unix_diag_handler = {
.owner = THIS_MODULE,
.family = AF_UNIX,
.dump = unix_diag_handler_dump,
};
static int __init unix_diag_init(void)
{
return sock_diag_register(&unix_diag_handler);
}
static void __exit unix_diag_exit(void)
{
sock_diag_unregister(&unix_diag_handler);
}
module_init(unix_diag_init);
module_exit(unix_diag_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("UNIX socket monitoring via SOCK_DIAG");
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 1 /* AF_LOCAL */);
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