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Date: Sat, 10 Mar 2018 18:57:50 +0800
From: Xin Long <lucien.xin@...il.com>
To: network dev <netdev@...r.kernel.org>
Cc: davem@...emloft.net, Eric Dumazet <edumazet@...gle.com>,
Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
Phil Sutter <phil@....cc>, Sabrina Dubroca <sd@...asysnail.net>
Subject: [PATCHv3 net] sock_diag: request _diag module only when the family or proto has been registered
Now when using 'ss' in iproute, kernel would try to load all _diag
modules, which also causes corresponding family and proto modules
to be loaded as well due to module dependencies.
Like after running 'ss', sctp, dccp, af_packet (if it works as a module)
would be loaded.
For example:
$ lsmod|grep sctp
$ ss
$ lsmod|grep sctp
sctp_diag 16384 0
sctp 323584 5 sctp_diag
inet_diag 24576 4 raw_diag,tcp_diag,sctp_diag,udp_diag
libcrc32c 16384 3 nf_conntrack,nf_nat,sctp
As these family and proto modules are loaded unintentionally, it
could cause some problems, like:
- Some debug tools use 'ss' to collect the socket info, which loads all
those diag and family and protocol modules. It's noisy for identifying
issues.
- Users usually expect to drop sctp init packet silently when they
have no sense of sctp protocol instead of sending abort back.
- It wastes resources (especially with multiple netns), and SCTP module
can't be unloaded once it's loaded.
...
In short, it's really inappropriate to have these family and proto
modules loaded unexpectedly when just doing debugging with inet_diag.
This patch is to introduce sock_load_diag_module() where it loads
the _diag module only when it's corresponding family or proto has
been already registered.
Note that we can't just load _diag module without the family or
proto loaded, as some symbols used in _diag module are from the
family or proto module.
v1->v2:
- move inet proto check to inet_diag to avoid a compiling err.
v2->v3:
- define sock_load_diag_module in sock.c and export one symbol
only.
- improve the changelog.
Reported-by: Sabrina Dubroca <sd@...asysnail.net>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Acked-by: Phil Sutter <phil@....cc>
Acked-by: Sabrina Dubroca <sd@...asysnail.net>
Signed-off-by: Xin Long <lucien.xin@...il.com>
---
include/linux/net.h | 1 +
include/net/sock.h | 1 +
net/core/sock.c | 21 +++++++++++++++++++++
net/core/sock_diag.c | 12 ++++--------
net/ipv4/inet_diag.c | 3 +--
net/socket.c | 5 +++++
6 files changed, 33 insertions(+), 10 deletions(-)
diff --git a/include/linux/net.h b/include/linux/net.h
index 91216b1..2a0391e 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -222,6 +222,7 @@ 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/net/sock.h b/include/net/sock.h
index 169c92a..ae23f3b 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1137,6 +1137,7 @@ struct proto {
int proto_register(struct proto *prot, int alloc_slab);
void proto_unregister(struct proto *prot);
+int sock_load_diag_module(int family, int protocol);
#ifdef SOCK_REFCNT_DEBUG
static inline void sk_refcnt_debug_inc(struct sock *sk)
diff --git a/net/core/sock.c b/net/core/sock.c
index c501499..85b0b64 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3261,6 +3261,27 @@ void proto_unregister(struct proto *prot)
}
EXPORT_SYMBOL(proto_unregister);
+int sock_load_diag_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);
+ }
+
+#ifdef CONFIG_INET
+ if (family == AF_INET &&
+ !rcu_access_pointer(inet_protos[protocol]))
+ return -ENOENT;
+#endif
+
+ return request_module("net-pf-%d-proto-%d-type-%d-%d", PF_NETLINK,
+ NETLINK_SOCK_DIAG, family, protocol);
+}
+EXPORT_SYMBOL(sock_load_diag_module);
+
#ifdef CONFIG_PROC_FS
static void *proto_seq_start(struct seq_file *seq, loff_t *pos)
__acquires(proto_list_mutex)
diff --git a/net/core/sock_diag.c b/net/core/sock_diag.c
index 146b50e..c37b5be 100644
--- a/net/core/sock_diag.c
+++ b/net/core/sock_diag.c
@@ -220,8 +220,7 @@ 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_load_diag_module(req->sdiag_family, 0);
mutex_lock(&sock_diag_table_mutex);
hndl = sock_diag_handlers[req->sdiag_family];
@@ -247,8 +246,7 @@ 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_load_diag_module(AF_INET, 0);
mutex_lock(&sock_diag_table_mutex);
if (inet_rcv_compat != NULL)
@@ -281,14 +279,12 @@ 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_load_diag_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_INET6);
+ sock_load_diag_module(AF_INET6, 0);
break;
}
return 0;
diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index a383f29..4e5bc4b 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_load_diag_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 a93c99b5..08847c3 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2587,6 +2587,11 @@ 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
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