Now when using 'ss' in iproute, kernel would try to load all _diag
modules. It causes the corresponding family or proto modules to be
loaded as well.
Like after 'ss -a', sctp, dccp, af_packet(if it works as a moudle)
will be loaded.
As these family or proto modules are loaded unexpectly, this might
have some security implications.
This patch is to introduce sock_diag_request_module() in which we
only request the _diag module when it's corresponding family or
proto has been registered.
Note that we can't just load _diag module without the family or
proto loaded, as some symbols in _diag module are from the family
or proto moudle.
Reported-by: Sabrina Dubroca <s...@queasysnail.net>
Signed-off-by: Xin Long <lucien....@gmail.com>
---
include/linux/net.h | 1 +
include/linux/sock_diag.h | 1 +
net/core/sock_diag.c | 32 ++++++++++++++++++++++++--------
net/ipv4/inet_diag.c | 3 +--
net/socket.c | 5 +++++
5 files changed, 32 insertions(+), 10 deletions(-)
diff --git a/include/linux/net.h b/include/linux/net.h
index d97d80d..6c7cf09 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -225,6 +225,7 @@ enum {
int sock_wake_async(struct socket_wq *sk_wq, int how, int band);
int sock_register(const struct net_proto_family *fam);
void sock_unregister(int family);
+bool sock_is_registered(int family);
int __sock_create(struct net *net, int family, int type, int proto,
struct socket **res, int kern);
int sock_create(int family, int type, int proto, struct socket **res);
diff --git a/include/linux/sock_diag.h b/include/linux/sock_diag.h
index a2f8109..e9a1b8d 100644
--- a/include/linux/sock_diag.h
+++ b/include/linux/sock_diag.h
@@ -77,4 +77,5 @@ bool sock_diag_has_destroy_listeners(const struct sock *sk)
void sock_diag_broadcast_destroy(struct sock *sk);
int sock_diag_destroy(struct sock *sk, int err);
+int sock_diag_request_module(int family, int protocol);
#endif
diff --git a/net/core/sock_diag.c b/net/core/sock_diag.c
index 217f4e3..caad6b6 100644
--- a/net/core/sock_diag.c
+++ b/net/core/sock_diag.c
@@ -7,6 +7,7 @@
#include <net/net_namespace.h>
#include <linux/module.h>
#include <net/sock.h>
+#include <net/protocol.h>
#include <linux/kernel.h>
#include <linux/tcp.h>
#include <linux/workqueue.h>
@@ -207,6 +208,25 @@ void sock_diag_unregister(const struct sock_diag_handler
*hnld)
}
EXPORT_SYMBOL_GPL(sock_diag_unregister);
+int sock_diag_request_module(int family, int protocol)
+{
+ if (!protocol) {
+ if (!sock_is_registered(family))
+ return -ENOENT;
+
+ return request_module("net-pf-%d-proto-%d-type-%d", PF_NETLINK,
+ NETLINK_SOCK_DIAG, family);
+ }
+
+ if (family == AF_INET &&
+ !rcu_access_pointer(inet_protos[protocol]))
+ return -ENOENT;
+
+ return request_module("net-pf-%d-proto-%d-type-%d-%d", PF_NETLINK,
+ NETLINK_SOCK_DIAG, family, protocol);
+}
+EXPORT_SYMBOL_GPL(sock_diag_request_module);
+
static int __sock_diag_cmd(struct sk_buff *skb, struct nlmsghdr *nlh)
{
int err;
@@ -220,8 +240,7 @@ static int __sock_diag_cmd(struct sk_buff *skb, struct
nlmsghdr *nlh)
return -EINVAL;
if (sock_diag_handlers[req->sdiag_family] == NULL)
- request_module("net-pf-%d-proto-%d-type-%d", PF_NETLINK,
- NETLINK_SOCK_DIAG, req->sdiag_family);
+ sock_diag_request_module(req->sdiag_family, 0);
mutex_lock(&sock_diag_table_mutex);
hndl = sock_diag_handlers[req->sdiag_family];
@@ -247,8 +266,7 @@ static int sock_diag_rcv_msg(struct sk_buff *skb, struct
nlmsghdr *nlh,
case TCPDIAG_GETSOCK:
case DCCPDIAG_GETSOCK:
if (inet_rcv_compat == NULL)
- request_module("net-pf-%d-proto-%d-type-%d", PF_NETLINK,
- NETLINK_SOCK_DIAG, AF_INET);
+ sock_diag_request_module(AF_INET, 0);
mutex_lock(&sock_diag_table_mutex);
if (inet_rcv_compat != NULL)
@@ -281,14 +299,12 @@ static int sock_diag_bind(struct net *net, int group)
case SKNLGRP_INET_TCP_DESTROY:
case SKNLGRP_INET_UDP_DESTROY:
if (!sock_diag_handlers[AF_INET])
- request_module("net-pf-%d-proto-%d-type-%d", PF_NETLINK,
- NETLINK_SOCK_DIAG, AF_INET);
+ sock_diag_request_module(AF_INET, 0);
break;
case SKNLGRP_INET6_TCP_DESTROY:
case SKNLGRP_INET6_UDP_DESTROY:
if (!sock_diag_handlers[AF_INET6])
- request_module("net-pf-%d-proto-%d-type-%d", PF_NETLINK,
- NETLINK_SOCK_DIAG, AF_INET);
+ sock_diag_request_module(AF_INET, 0);
break;
}
return 0;
diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index c9c35b6..d10c8fa 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -53,8 +53,7 @@ static DEFINE_MUTEX(inet_diag_table_mutex);
static const struct inet_diag_handler *inet_diag_lock_handler(int proto)
{
if (!inet_diag_table[proto])
- request_module("net-pf-%d-proto-%d-type-%d-%d", PF_NETLINK,
- NETLINK_SOCK_DIAG, AF_INET, proto);
+ sock_diag_request_module(AF_INET, proto);
mutex_lock(&inet_diag_table_mutex);
if (!inet_diag_table[proto])
diff --git a/net/socket.c b/net/socket.c
index c729625..733d657 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2590,6 +2590,11 @@ void sock_unregister(int family)
}
EXPORT_SYMBOL(sock_unregister);
+bool sock_is_registered(int family)
+{
+ return family < NPROTO && rcu_access_pointer(net_families[family]);
+}
+
static int __init sock_init(void)
{
int err;
--
2.1.0
