From: Eric Dumazet edumazet@google.com
[ Upstream commit 9c1be1935fb68b2413796cdc03d019b8cf35ab51 ]
While testing a patch that will follow later ("net: add netns refcount tracker to struct nsproxy") I found that devtmpfs_init() was called before init_net was initialized.
This is a bug, because devtmpfs_setup() calls ksys_unshare(CLONE_NEWNS);
This has the effect of increasing init_net refcount, which will be later overwritten to 1, as part of setup_net(&init_net)
We had too many prior patches [1] trying to work around the root cause.
Really, make sure init_net is in BSS section, and that net_ns_init() is called earlier at boot time.
Note that another patch ("vfs: add netns refcount tracker to struct fs_context") also will need net_ns_init() being called before vfs_caches_init()
As a bonus, this patch saves around 4KB in .data section.
[1]
f8c46cb39079 ("netns: do not call pernet ops for not yet set up init_net namespace") b5082df8019a ("net: Initialise init_net.count to 1") 734b65417b24 ("net: Statically initialize init_net.dev_base_head")
v2: fixed a build error reported by kernel build bots (CONFIG_NET=n)
Signed-off-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/net_namespace.h | 6 ++++++ init/main.c | 2 ++ net/core/dev.c | 3 +-- net/core/net_namespace.c | 17 +++++------------ 4 files changed, 14 insertions(+), 14 deletions(-)
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index bb5fa5914032..2ba326f9e004 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -479,4 +479,10 @@ static inline void fnhe_genid_bump(struct net *net) atomic_inc(&net->fnhe_genid); }
+#ifdef CONFIG_NET +void net_ns_init(void); +#else +static inline void net_ns_init(void) {} +#endif + #endif /* __NET_NET_NAMESPACE_H */ diff --git a/init/main.c b/init/main.c index bb984ed79de0..cb68bc48a682 100644 --- a/init/main.c +++ b/init/main.c @@ -99,6 +99,7 @@ #include <linux/kcsan.h> #include <linux/init_syscalls.h> #include <linux/stackdepot.h> +#include <net/net_namespace.h>
#include <asm/io.h> #include <asm/bugs.h> @@ -1113,6 +1114,7 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void) key_init(); security_init(); dbg_late_init(); + net_ns_init(); vfs_caches_init(); pagecache_init(); signals_init(); diff --git a/net/core/dev.c b/net/core/dev.c index 2078d04c6482..8c47e0f2075d 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -11403,8 +11403,7 @@ static int __net_init netdev_init(struct net *net) BUILD_BUG_ON(GRO_HASH_BUCKETS > 8 * sizeof_field(struct napi_struct, gro_bitmask));
- if (net != &init_net) - INIT_LIST_HEAD(&net->dev_base_head); + INIT_LIST_HEAD(&net->dev_base_head);
net->dev_name_head = netdev_create_hash(); if (net->dev_name_head == NULL) diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index 9702d2b0d920..9745cb6fdf51 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -44,13 +44,7 @@ EXPORT_SYMBOL_GPL(net_rwsem); static struct key_tag init_net_key_domain = { .usage = REFCOUNT_INIT(1) }; #endif
-struct net init_net = { - .ns.count = REFCOUNT_INIT(1), - .dev_base_head = LIST_HEAD_INIT(init_net.dev_base_head), -#ifdef CONFIG_KEYS - .key_domain = &init_net_key_domain, -#endif -}; +struct net init_net; EXPORT_SYMBOL(init_net);
static bool init_net_initialized; @@ -1081,7 +1075,7 @@ static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid, rtnl_set_sk_err(net, RTNLGRP_NSID, err); }
-static int __init net_ns_init(void) +void __init net_ns_init(void) { struct net_generic *ng;
@@ -1102,6 +1096,9 @@ static int __init net_ns_init(void)
rcu_assign_pointer(init_net.gen, ng);
+#ifdef CONFIG_KEYS + init_net.key_domain = &init_net_key_domain; +#endif down_write(&pernet_ops_rwsem); if (setup_net(&init_net, &init_user_ns)) panic("Could not setup the initial network namespace"); @@ -1116,12 +1113,8 @@ static int __init net_ns_init(void) RTNL_FLAG_DOIT_UNLOCKED); rtnl_register(PF_UNSPEC, RTM_GETNSID, rtnl_net_getid, rtnl_net_dumpid, RTNL_FLAG_DOIT_UNLOCKED); - - return 0; }
-pure_initcall(net_ns_init); - static void free_exit_list(struct pernet_operations *ops, struct list_head *net_exit_list) { ops_pre_exit_list(ops, net_exit_list);