Currently when user changes link properties, TIPC first checks if
user's command message contains media name or bearer name through
tipc_media_find() or tipc_bearer_find() which is protected by RTNL
lock. But when tipc_nl_compat_link_set() conducts the checking with
the two functions, it doesn't hold RTNL lock at all, as a result,
the following complaints were reported:
audit: type=1400 audit(1514679888.244:9): avc: denied { write } for
pid=3194 comm="syzkaller021477" path="socket:[11143]" dev="sockfs"
ino=11143 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tclass=netlink_generic_socket permissive=1
=============================
WARNING: suspicious RCU usage
4.15.0-rc5+ #152 Not tainted
-----------------------------
net/tipc/bearer.c:177 suspicious rcu_dereference_protected() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
2 locks held by syzkaller021477/3194:
#0: (cb_lock){++++}, at: [<00000000d20133ea>] genl_rcv+0x19/0x40
net/netlink/genetlink.c:634
#1: (genl_mutex){+.+.}, at: [<00000000fcc5d1bc>] genl_lock
net/netlink/genetlink.c:33 [inline]
#1: (genl_mutex){+.+.}, at: [<00000000fcc5d1bc>] genl_rcv_msg+0x115/0x140
net/netlink/genetlink.c:622
stack backtrace:
CPU: 1 PID: 3194 Comm: syzkaller021477 Not tainted 4.15.0-rc5+ #152
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:53
lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4585
tipc_bearer_find+0x2b4/0x3b0 net/tipc/bearer.c:177
tipc_nl_compat_link_set+0x329/0x9f0 net/tipc/netlink_compat.c:729
__tipc_nl_compat_doit net/tipc/netlink_compat.c:288 [inline]
tipc_nl_compat_doit+0x15b/0x660 net/tipc/netlink_compat.c:335
tipc_nl_compat_handle net/tipc/netlink_compat.c:1119 [inline]
tipc_nl_compat_recv+0x112f/0x18f0 net/tipc/netlink_compat.c:1201
genl_family_rcv_msg+0x7b7/0xfb0 net/netlink/genetlink.c:599
genl_rcv_msg+0xb2/0x140 net/netlink/genetlink.c:624
netlink_rcv_skb+0x21e/0x460 net/netlink/af_netlink.c:2408
genl_rcv+0x28/0x40 net/netlink/genetlink.c:635
netlink_unicast_kernel net/netlink/af_netlink.c:1275 [inline]
netlink_unicast+0x4e8/0x6f0 net/netlink/af_netlink.c:1301
netlink_sendmsg+0xa4a/0xe60 net/netlink/af_netlink.c:1864
sock_sendmsg_nosec net/socket.c:636 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:646
sock_write_iter+0x31a/0x5d0 net/socket.c:915
call_write_iter include/linux/fs.h:1772 [inline]
new_sync_write fs/read_write.c:469 [inline]
__vfs_write+0x684/0x970 fs/read_write.c:482
vfs_write+0x189/0x510 fs/read_write.c:544
SYSC_write fs/read_write.c:589 [inline]
SyS_write+0xef/0x220 fs/read_write.c:581
do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline]
do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389
entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:129
In order to correct the mistake, __tipc_nl_compat_doit() has been
protected by RTNL lock, which means the whole operation of setting
bearer/media properties is under RTNL protection.
Signed-off-by: Ying Xue <ying....@windriver.com>
Reported-by: syzbot <syzbot+6345fd433db009b29...@syzkaller.appspotmail.com>
---
v3:
- Optimized return method of __tipc_nl_bearer_enable() regarding
the comments from David M and Kirill Tkhai
- Moved the allocations of memory in __tipc_nl_compat_doit() out
of RTNL lock to minimize the time of holding RTNL lock according
to the suggestion of Kirill Tkhai.
v2:
- The whole operation of setting bearer/media properties has been
protected under RTNL, as per feedback from David M.
net/tipc/bearer.c | 82 +++++++++++++++++++++++++++++------------------
net/tipc/bearer.h | 4 +++
net/tipc/net.c | 15 +++++++--
net/tipc/net.h | 1 +
net/tipc/netlink_compat.c | 43 +++++++++++++------------
5 files changed, 91 insertions(+), 54 deletions(-)
diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index c800147..3e3dce3 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c
@@ -813,7 +813,7 @@ int tipc_nl_bearer_get(struct sk_buff *skb, struct
genl_info *info)
return err;
}
-int tipc_nl_bearer_disable(struct sk_buff *skb, struct genl_info *info)
+int __tipc_nl_bearer_disable(struct sk_buff *skb, struct genl_info *info)
{
int err;
char *name;
@@ -835,20 +835,27 @@ int tipc_nl_bearer_disable(struct sk_buff *skb, struct
genl_info *info)
name = nla_data(attrs[TIPC_NLA_BEARER_NAME]);
- rtnl_lock();
bearer = tipc_bearer_find(net, name);
- if (!bearer) {
- rtnl_unlock();
+ if (!bearer)
return -EINVAL;
- }
bearer_disable(net, bearer);
- rtnl_unlock();
return 0;
}
-int tipc_nl_bearer_enable(struct sk_buff *skb, struct genl_info *info)
+int tipc_nl_bearer_disable(struct sk_buff *skb, struct genl_info *info)
+{
+ int err;
+
+ rtnl_lock();
+ err = __tipc_nl_bearer_disable(skb, info);
+ rtnl_unlock();
+
+ return err;
+}
+
+int __tipc_nl_bearer_enable(struct sk_buff *skb, struct genl_info *info)
{
int err;
char *bearer;
@@ -890,15 +897,18 @@ int tipc_nl_bearer_enable(struct sk_buff *skb, struct
genl_info *info)
prio = nla_get_u32(props[TIPC_NLA_PROP_PRIO]);
}
+ return tipc_enable_bearer(net, bearer, domain, prio, attrs);
+}
+
+int tipc_nl_bearer_enable(struct sk_buff *skb, struct genl_info *info)
+{
+ int err;
+
rtnl_lock();
- err = tipc_enable_bearer(net, bearer, domain, prio, attrs);
- if (err) {
- rtnl_unlock();
- return err;
- }
+ err = __tipc_nl_bearer_enable(skb, info);
rtnl_unlock();
- return 0;
+ return err;
}
int tipc_nl_bearer_add(struct sk_buff *skb, struct genl_info *info)
@@ -944,7 +954,7 @@ int tipc_nl_bearer_add(struct sk_buff *skb, struct
genl_info *info)
return 0;
}
-int tipc_nl_bearer_set(struct sk_buff *skb, struct genl_info *info)
+int __tipc_nl_bearer_set(struct sk_buff *skb, struct genl_info *info)
{
int err;
char *name;
@@ -965,22 +975,17 @@ int tipc_nl_bearer_set(struct sk_buff *skb, struct
genl_info *info)
return -EINVAL;
name = nla_data(attrs[TIPC_NLA_BEARER_NAME]);
- rtnl_lock();
b = tipc_bearer_find(net, name);
- if (!b) {
- rtnl_unlock();
+ if (!b)
return -EINVAL;
- }
if (attrs[TIPC_NLA_BEARER_PROP]) {
struct nlattr *props[TIPC_NLA_PROP_MAX + 1];
err = tipc_nl_parse_link_prop(attrs[TIPC_NLA_BEARER_PROP],
props);
- if (err) {
- rtnl_unlock();
+ if (err)
return err;
- }
if (props[TIPC_NLA_PROP_TOL])
b->tolerance = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
@@ -989,11 +994,21 @@ int tipc_nl_bearer_set(struct sk_buff *skb, struct
genl_info *info)
if (props[TIPC_NLA_PROP_WIN])
b->window = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
}
- rtnl_unlock();
return 0;
}
+int tipc_nl_bearer_set(struct sk_buff *skb, struct genl_info *info)
+{
+ int err;
+
+ rtnl_lock();
+ err = __tipc_nl_bearer_set(skb, info);
+ rtnl_unlock();
+
+ return err;
+}
+
static int __tipc_nl_add_media(struct tipc_nl_msg *msg,
struct tipc_media *media, int nlflags)
{
@@ -1115,7 +1130,7 @@ int tipc_nl_media_get(struct sk_buff *skb, struct
genl_info *info)
return err;
}
-int tipc_nl_media_set(struct sk_buff *skb, struct genl_info *info)
+int __tipc_nl_media_set(struct sk_buff *skb, struct genl_info *info)
{
int err;
char *name;
@@ -1133,22 +1148,17 @@ int tipc_nl_media_set(struct sk_buff *skb, struct
genl_info *info)
return -EINVAL;
name = nla_data(attrs[TIPC_NLA_MEDIA_NAME]);
- rtnl_lock();
m = tipc_media_find(name);
- if (!m) {
- rtnl_unlock();
+ if (!m)
return -EINVAL;
- }
if (attrs[TIPC_NLA_MEDIA_PROP]) {
struct nlattr *props[TIPC_NLA_PROP_MAX + 1];
err = tipc_nl_parse_link_prop(attrs[TIPC_NLA_MEDIA_PROP],
props);
- if (err) {
- rtnl_unlock();
+ if (err)
return err;
- }
if (props[TIPC_NLA_PROP_TOL])
m->tolerance = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
@@ -1157,7 +1167,17 @@ int tipc_nl_media_set(struct sk_buff *skb, struct
genl_info *info)
if (props[TIPC_NLA_PROP_WIN])
m->window = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
}
- rtnl_unlock();
return 0;
}
+
+int tipc_nl_media_set(struct sk_buff *skb, struct genl_info *info)
+{
+ int err;
+
+ rtnl_lock();
+ err = __tipc_nl_media_set(skb, info);
+ rtnl_unlock();
+
+ return err;
+}
diff --git a/net/tipc/bearer.h b/net/tipc/bearer.h
index 42d6eee..a53613d 100644
--- a/net/tipc/bearer.h
+++ b/net/tipc/bearer.h
@@ -188,15 +188,19 @@ extern struct tipc_media udp_media_info;
#endif
int tipc_nl_bearer_disable(struct sk_buff *skb, struct genl_info *info);
+int __tipc_nl_bearer_disable(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_bearer_enable(struct sk_buff *skb, struct genl_info *info);
+int __tipc_nl_bearer_enable(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_bearer_dump(struct sk_buff *skb, struct netlink_callback *cb);
int tipc_nl_bearer_get(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_bearer_set(struct sk_buff *skb, struct genl_info *info);
+int __tipc_nl_bearer_set(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_bearer_add(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_media_dump(struct sk_buff *skb, struct netlink_callback *cb);
int tipc_nl_media_get(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_media_set(struct sk_buff *skb, struct genl_info *info);
+int __tipc_nl_media_set(struct sk_buff *skb, struct genl_info *info);
int tipc_media_set_priority(const char *name, u32 new_value);
int tipc_media_set_window(const char *name, u32 new_value);
diff --git a/net/tipc/net.c b/net/tipc/net.c
index 719c592..1a2fde0 100644
--- a/net/tipc/net.c
+++ b/net/tipc/net.c
@@ -200,7 +200,7 @@ int tipc_nl_net_dump(struct sk_buff *skb, struct
netlink_callback *cb)
return skb->len;
}
-int tipc_nl_net_set(struct sk_buff *skb, struct genl_info *info)
+int __tipc_nl_net_set(struct sk_buff *skb, struct genl_info *info)
{
struct net *net = sock_net(skb->sk);
struct tipc_net *tn = net_generic(net, tipc_net_id);
@@ -241,10 +241,19 @@ int tipc_nl_net_set(struct sk_buff *skb, struct genl_info
*info)
if (!tipc_addr_node_valid(addr))
return -EINVAL;
- rtnl_lock();
tipc_net_start(net, addr);
- rtnl_unlock();
}
return 0;
}
+
+int tipc_nl_net_set(struct sk_buff *skb, struct genl_info *info)
+{
+ int err;
+
+ rtnl_lock();
+ err = __tipc_nl_net_set(skb, info);
+ rtnl_unlock();
+
+ return err;
+}
diff --git a/net/tipc/net.h b/net/tipc/net.h
index c7c2549..c0306aa 100644
--- a/net/tipc/net.h
+++ b/net/tipc/net.h
@@ -47,5 +47,6 @@ void tipc_net_stop(struct net *net);
int tipc_nl_net_dump(struct sk_buff *skb, struct netlink_callback *cb);
int tipc_nl_net_set(struct sk_buff *skb, struct genl_info *info);
+int __tipc_nl_net_set(struct sk_buff *skb, struct genl_info *info);
#endif
diff --git a/net/tipc/netlink_compat.c b/net/tipc/netlink_compat.c
index e48f0b2..4492cda 100644
--- a/net/tipc/netlink_compat.c
+++ b/net/tipc/netlink_compat.c
@@ -285,10 +285,6 @@ static int __tipc_nl_compat_doit(struct
tipc_nl_compat_cmd_doit *cmd,
if (!trans_buf)
return -ENOMEM;
- err = (*cmd->transcode)(cmd, trans_buf, msg);
- if (err)
- goto trans_out;
-
attrbuf = kmalloc((tipc_genl_family.maxattr + 1) *
sizeof(struct nlattr *), GFP_KERNEL);
if (!attrbuf) {
@@ -296,27 +292,34 @@ static int __tipc_nl_compat_doit(struct
tipc_nl_compat_cmd_doit *cmd,
goto trans_out;
}
- err = nla_parse(attrbuf, tipc_genl_family.maxattr,
- (const struct nlattr *)trans_buf->data,
- trans_buf->len, NULL, NULL);
- if (err)
- goto parse_out;
-
doit_buf = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
if (!doit_buf) {
err = -ENOMEM;
- goto parse_out;
+ goto attrbuf_out;
}
- doit_buf->sk = msg->dst_sk;
-
memset(&info, 0, sizeof(info));
info.attrs = attrbuf;
+ rtnl_lock();
+ err = (*cmd->transcode)(cmd, trans_buf, msg);
+ if (err)
+ goto doit_out;
+
+ err = nla_parse(attrbuf, tipc_genl_family.maxattr,
+ (const struct nlattr *)trans_buf->data,
+ trans_buf->len, NULL, NULL);
+ if (err)
+ goto doit_out;
+
+ doit_buf->sk = msg->dst_sk;
+
err = (*cmd->doit)(doit_buf, &info);
+doit_out:
+ rtnl_unlock();
kfree_skb(doit_buf);
-parse_out:
+attrbuf_out:
kfree(attrbuf);
trans_out:
kfree_skb(trans_buf);
@@ -722,13 +725,13 @@ static int tipc_nl_compat_link_set(struct
tipc_nl_compat_cmd_doit *cmd,
media = tipc_media_find(lc->name);
if (media) {
- cmd->doit = &tipc_nl_media_set;
+ cmd->doit = &__tipc_nl_media_set;
return tipc_nl_compat_media_set(skb, msg);
}
bearer = tipc_bearer_find(msg->net, lc->name);
if (bearer) {
- cmd->doit = &tipc_nl_bearer_set;
+ cmd->doit = &__tipc_nl_bearer_set;
return tipc_nl_compat_bearer_set(skb, msg);
}
@@ -1089,12 +1092,12 @@ static int tipc_nl_compat_handle(struct
tipc_nl_compat_msg *msg)
return tipc_nl_compat_dumpit(&dump, msg);
case TIPC_CMD_ENABLE_BEARER:
msg->req_type = TIPC_TLV_BEARER_CONFIG;
- doit.doit = tipc_nl_bearer_enable;
+ doit.doit = __tipc_nl_bearer_enable;
doit.transcode = tipc_nl_compat_bearer_enable;
return tipc_nl_compat_doit(&doit, msg);
case TIPC_CMD_DISABLE_BEARER:
msg->req_type = TIPC_TLV_BEARER_NAME;
- doit.doit = tipc_nl_bearer_disable;
+ doit.doit = __tipc_nl_bearer_disable;
doit.transcode = tipc_nl_compat_bearer_disable;
return tipc_nl_compat_doit(&doit, msg);
case TIPC_CMD_SHOW_LINK_STATS:
@@ -1148,12 +1151,12 @@ static int tipc_nl_compat_handle(struct
tipc_nl_compat_msg *msg)
return tipc_nl_compat_dumpit(&dump, msg);
case TIPC_CMD_SET_NODE_ADDR:
msg->req_type = TIPC_TLV_NET_ADDR;
- doit.doit = tipc_nl_net_set;
+ doit.doit = __tipc_nl_net_set;
doit.transcode = tipc_nl_compat_net_set;
return tipc_nl_compat_doit(&doit, msg);
case TIPC_CMD_SET_NETID:
msg->req_type = TIPC_TLV_UNSIGNED;
- doit.doit = tipc_nl_net_set;
+ doit.doit = __tipc_nl_net_set;
doit.transcode = tipc_nl_compat_net_set;
return tipc_nl_compat_doit(&doit, msg);
case TIPC_CMD_GET_NETID:
--
2.7.4
