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net: add a refcount tracker for kernel sockets

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Commit ffa84b5ffb ("net: add netns refcount tracker to struct sock")
added a tracker to sockets, but did not track kernel sockets.

We still have syzbot reports hinting about netns being destroyed
while some kernel TCP sockets had not been dismantled.

This patch tracks kernel sockets, and adds a ref_tracker_dir_print()
call to net_free() right before the netns is freed.

Normally, each layer is responsible for properly releasing its
kernel sockets before last call to net_free().

This debugging facility is enabled with CONFIG_NET_NS_REFCNT_TRACKER=y

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Tested-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2022-10-20 23:20:18 +00:00
committed by David S. Miller
parent b29e0dece4
commit 0cafd77dcd
5 changed files with 55 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

30
include/net/net_namespace.h
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@@ -92,7 +92,9 @@ struct net {
struct ns_common ns;
struct ref_tracker_dir refcnt_tracker;
struct ref_tracker_dir notrefcnt_tracker; /* tracker for objects not
* refcounted against netns
*/
struct list_head dev_base_head;
struct proc_dir_entry *proc_net;
struct proc_dir_entry *proc_net_stat;
@@ -320,19 +322,31 @@ static inline int check_net(const struct net *net)
#endif
static inline void netns_tracker_alloc(struct net *net,
netns_tracker *tracker, gfp_t gfp)
static inline void __netns_tracker_alloc(struct net *net,
netns_tracker *tracker,
bool refcounted,
gfp_t gfp)
{
#ifdef CONFIG_NET_NS_REFCNT_TRACKER
ref_tracker_alloc(&net->refcnt_tracker, tracker, gfp);
ref_tracker_alloc(refcounted ? &net->refcnt_tracker :
&net->notrefcnt_tracker,
tracker, gfp);
#endif
}
static inline void netns_tracker_free(struct net *net,
netns_tracker *tracker)
static inline void netns_tracker_alloc(struct net *net, netns_tracker *tracker,
gfp_t gfp)
{
__netns_tracker_alloc(net, tracker, true, gfp);
}
static inline void __netns_tracker_free(struct net *net,
netns_tracker *tracker,
bool refcounted)
{
#ifdef CONFIG_NET_NS_REFCNT_TRACKER
ref_tracker_free(&net->refcnt_tracker, tracker);
ref_tracker_free(refcounted ? &net->refcnt_tracker :
&net->notrefcnt_tracker, tracker);
#endif
}
@@ -346,7 +360,7 @@ static inline struct net *get_net_track(struct net *net,
static inline void put_net_track(struct net *net, netns_tracker *tracker)
{
netns_tracker_free(net, tracker);
__netns_tracker_free(net, tracker, true);
put_net(net);
}