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Message-ID: <20220701072519.96097-1-kuniyu@amazon.com>
Date: Fri, 1 Jul 2022 00:25:19 -0700
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
CC: Sachin Sant <sachinp@...ux.ibm.com>,
Leonard Crestez <cdleonard@...il.com>,
Kuniyuki Iwashima <kuniyu@...zon.com>,
"Kuniyuki Iwashima" <kuni1840@...il.com>, <netdev@...r.kernel.org>
Subject: [PATCH v1 net-next] af_unix: Put a named socket in the global hash table.
Commit cf2f225e2653 ("af_unix: Put a socket into a per-netns hash
table.") accidentally broke user API for named sockets. A named
socket was able to connect() to a peer in the same mount namespace
even if they were in different network namespaces.
The commit put all sockets into each per-netns hash table. As a
result, connect() to a socket in a different netns failed to find
the peer and returned -ECONNREFUSED even when they had the same
mount namespace.
We can reproduce this issue by
Console A:
# python3
>>> from socket import *
>>> s = socket(AF_UNIX, SOCK_STREAM, 0)
>>> s.bind('test')
>>> s.listen(32)
Console B:
# ip netns add test
# ip netns exec test sh
# python3
>>> from socket import *
>>> s = socket(AF_UNIX, SOCK_STREAM, 0)
>>> s.connect('test')
Note when dumping sockets by sock_diag, procfs, and bpf_iter, they are
filtered only by netns. In other words, sockets with different netns
and the same mount ns are skipped while iterating sockets. Thus, we
need a fix only for finding a peer socket.
This patch adds a global hash table for named sockets, links them with
sk_bind_node, and uses it in unix_find_socket_byinode(). By doing so,
we can keep all sockets in per-netns hash tables and dump them easily.
Thank Sachin Sant and Leonard Crestez for reports, logs and a reproducer.
Fixes: cf2f225e2653 ("af_unix: Put a socket into a per-netns hash table.")
Reported-by: Sachin Sant <sachinp@...ux.ibm.com>
Reported-by: Leonard Crestez <cdleonard@...il.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
net/unix/af_unix.c | 47 ++++++++++++++++++++++++++++++++++++----------
1 file changed, 37 insertions(+), 10 deletions(-)
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 49f6626330c3..526b872cc710 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -119,6 +119,8 @@
#include "scm.h"
static atomic_long_t unix_nr_socks;
+static struct hlist_head bsd_socket_buckets[UNIX_HASH_SIZE / 2];
+static spinlock_t bsd_socket_locks[UNIX_HASH_SIZE / 2];
/* SMP locking strategy:
* hash table is protected with spinlock.
@@ -328,6 +330,24 @@ static void unix_insert_unbound_socket(struct net *net, struct sock *sk)
spin_unlock(&net->unx.table.locks[sk->sk_hash]);
}
+static void unix_insert_bsd_socket(struct sock *sk)
+{
+ spin_lock(&bsd_socket_locks[sk->sk_hash]);
+ sk_add_bind_node(sk, &bsd_socket_buckets[sk->sk_hash]);
+ spin_unlock(&bsd_socket_locks[sk->sk_hash]);
+}
+
+static void unix_remove_bsd_socket(struct sock *sk)
+{
+ if (!hlist_unhashed(&sk->sk_bind_node)) {
+ spin_lock(&bsd_socket_locks[sk->sk_hash]);
+ __sk_del_bind_node(sk);
+ spin_unlock(&bsd_socket_locks[sk->sk_hash]);
+
+ sk_node_init(&sk->sk_bind_node);
+ }
+}
+
static struct sock *__unix_find_socket_byname(struct net *net,
struct sockaddr_un *sunname,
int len, unsigned int hash)
@@ -358,22 +378,22 @@ static inline struct sock *unix_find_socket_byname(struct net *net,
return s;
}
-static struct sock *unix_find_socket_byinode(struct net *net, struct inode *i)
+static struct sock *unix_find_socket_byinode(struct inode *i)
{
unsigned int hash = unix_bsd_hash(i);
struct sock *s;
- spin_lock(&net->unx.table.locks[hash]);
- sk_for_each(s, &net->unx.table.buckets[hash]) {
+ spin_lock(&bsd_socket_locks[hash]);
+ sk_for_each_bound(s, &bsd_socket_buckets[hash]) {
struct dentry *dentry = unix_sk(s)->path.dentry;
if (dentry && d_backing_inode(dentry) == i) {
sock_hold(s);
- spin_unlock(&net->unx.table.locks[hash]);
+ spin_unlock(&bsd_socket_locks[hash]);
return s;
}
}
- spin_unlock(&net->unx.table.locks[hash]);
+ spin_unlock(&bsd_socket_locks[hash]);
return NULL;
}
@@ -577,6 +597,7 @@ static void unix_release_sock(struct sock *sk, int embrion)
int state;
unix_remove_socket(sock_net(sk), sk);
+ unix_remove_bsd_socket(sk);
/* Clear state */
unix_state_lock(sk);
@@ -988,8 +1009,8 @@ static int unix_release(struct socket *sock)
return 0;
}
-static struct sock *unix_find_bsd(struct net *net, struct sockaddr_un *sunaddr,
- int addr_len, int type)
+static struct sock *unix_find_bsd(struct sockaddr_un *sunaddr, int addr_len,
+ int type)
{
struct inode *inode;
struct path path;
@@ -1010,7 +1031,7 @@ static struct sock *unix_find_bsd(struct net *net, struct sockaddr_un *sunaddr,
if (!S_ISSOCK(inode->i_mode))
goto path_put;
- sk = unix_find_socket_byinode(net, inode);
+ sk = unix_find_socket_byinode(inode);
if (!sk)
goto path_put;
@@ -1058,7 +1079,7 @@ static struct sock *unix_find_other(struct net *net,
struct sock *sk;
if (sunaddr->sun_path[0])
- sk = unix_find_bsd(net, sunaddr, addr_len, type);
+ sk = unix_find_bsd(sunaddr, addr_len, type);
else
sk = unix_find_abstract(net, sunaddr, addr_len, type);
@@ -1179,6 +1200,7 @@ static int unix_bind_bsd(struct sock *sk, struct sockaddr_un *sunaddr,
u->path.dentry = dget(dentry);
__unix_set_addr_hash(net, sk, addr, new_hash);
unix_table_double_unlock(net, old_hash, new_hash);
+ unix_insert_bsd_socket(sk);
mutex_unlock(&u->bindlock);
done_path_create(&parent, dentry);
return 0;
@@ -3682,10 +3704,15 @@ static void __init bpf_iter_register(void)
static int __init af_unix_init(void)
{
- int rc = -1;
+ int i, rc = -1;
BUILD_BUG_ON(sizeof(struct unix_skb_parms) > sizeof_field(struct sk_buff, cb));
+ for (i = 0; i < UNIX_HASH_SIZE / 2; i++) {
+ spin_lock_init(&bsd_socket_locks[i]);
+ INIT_HLIST_HEAD(&bsd_socket_buckets[i]);
+ }
+
rc = proto_register(&unix_dgram_proto, 1);
if (rc != 0) {
pr_crit("%s: Cannot create unix_sock SLAB cache!\n", __func__);
--
2.30.2
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