| Message ID | 1560341370-24197-1-git-send-email-wenbinzeng@tencent.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | auth_gss: netns refcount leaks when use-gss-proxy==1 | expand |
I lost track, what happened to these patches? --b. On Wed, Jun 12, 2019 at 08:09:27PM +0800, Wenbin Zeng wrote: > This patch series fixes an auth_gss bug that results in netns refcount > leaks when use-gss-proxy is set to 1. > > The problem was found in privileged docker containers with gssproxy service > enabled and /proc/net/rpc/use-gss-proxy set to 1, the corresponding > struct net->count ends up at 2 after container gets killed, the consequence > is that the struct net cannot be freed. > > It turns out that write_gssp() called gssp_rpc_create() to create a rpc > client, this increases net->count by 2; rpcsec_gss_exit_net() is supposed > to decrease net->count but it never gets called because its call-path is: > net->count==0 -> cleanup_net -> ops_exit_list -> rpcsec_gss_exit_net > Before rpcsec_gss_exit_net() gets called, net->count cannot reach 0, this > is a deadlock situation. > > To fix the problem, we must break the deadlock, rpcsec_gss_exit_net() > should move out of the put() path and find another chance to get called, > I think nsfs_evict() is a good place to go, when netns inode gets evicted > we call rpcsec_gss_exit_net() to free the rpc client, this requires a new > callback i.e. evict to be added in struct proc_ns_operations, and add > netns_evict() as one of netns_operations as well. > > v1->v2: > * in nsfs_evict(), move ->evict() in front of ->put() > v2->v3: > * rpcsec_gss_evict_net() directly call gss_svc_shutdown_net() regardless > if gssp_clnt is null, this is exactly same to what rpcsec_gss_exit_net() > previously did > > Wenbin Zeng (3): > nsfs: add evict callback into struct proc_ns_operations > netns: add netns_evict into netns_operations > auth_gss: fix deadlock that blocks rpcsec_gss_exit_net when > use-gss-proxy==1 > > fs/nsfs.c | 2 ++ > include/linux/proc_ns.h | 1 + > include/net/net_namespace.h | 1 + > net/core/net_namespace.c | 12 ++++++++++++ > net/sunrpc/auth_gss/auth_gss.c | 4 ++-- > 5 files changed, 18 insertions(+), 2 deletions(-) > > -- > 1.8.3.1
在 2019/8/2 3:53, J. Bruce Fields 写道: > I lost track, what happened to these patches? > > --b. > > On Wed, Jun 12, 2019 at 08:09:27PM +0800, Wenbin Zeng wrote: >> This patch series fixes an auth_gss bug that results in netns refcount >> leaks when use-gss-proxy is set to 1. >> >> The problem was found in privileged docker containers with gssproxy service >> enabled and /proc/net/rpc/use-gss-proxy set to 1, the corresponding >> struct net->count ends up at 2 after container gets killed, the consequence >> is that the struct net cannot be freed. >> >> It turns out that write_gssp() called gssp_rpc_create() to create a rpc >> client, this increases net->count by 2; rpcsec_gss_exit_net() is supposed >> to decrease net->count but it never gets called because its call-path is: >> net->count==0 -> cleanup_net -> ops_exit_list -> rpcsec_gss_exit_net >> Before rpcsec_gss_exit_net() gets called, net->count cannot reach 0, this >> is a deadlock situation. >> >> To fix the problem, we must break the deadlock, rpcsec_gss_exit_net() >> should move out of the put() path and find another chance to get called, >> I think nsfs_evict() is a good place to go, when netns inode gets evicted >> we call rpcsec_gss_exit_net() to free the rpc client, this requires a new >> callback i.e. evict to be added in struct proc_ns_operations, and add >> netns_evict() as one of netns_operations as well. >> >> v1->v2: >> * in nsfs_evict(), move ->evict() in front of ->put() >> v2->v3: >> * rpcsec_gss_evict_net() directly call gss_svc_shutdown_net() regardless >> if gssp_clnt is null, this is exactly same to what rpcsec_gss_exit_net() >> previously did >> >> Wenbin Zeng (3): >> nsfs: add evict callback into struct proc_ns_operations >> netns: add netns_evict into netns_operations >> auth_gss: fix deadlock that blocks rpcsec_gss_exit_net when >> use-gss-proxy==1 >> >> fs/nsfs.c | 2 ++ >> include/linux/proc_ns.h | 1 + >> include/net/net_namespace.h | 1 + >> net/core/net_namespace.c | 12 ++++++++++++ >> net/sunrpc/auth_gss/auth_gss.c | 4 ++-- >> 5 files changed, 18 insertions(+), 2 deletions(-) >> >> -- >> 1.8.3.1 These patchsets don't seem to merge into the mainline, are there any other patches that fix this bug?
This patch series fixes an auth_gss bug that results in netns refcount leaks when use-gss-proxy is set to 1. The problem was found in privileged docker containers with gssproxy service enabled and /proc/net/rpc/use-gss-proxy set to 1, the corresponding struct net->count ends up at 2 after container gets killed, the consequence is that the struct net cannot be freed. It turns out that write_gssp() called gssp_rpc_create() to create a rpc client, this increases net->count by 2; rpcsec_gss_exit_net() is supposed to decrease net->count but it never gets called because its call-path is: net->count==0 -> cleanup_net -> ops_exit_list -> rpcsec_gss_exit_net Before rpcsec_gss_exit_net() gets called, net->count cannot reach 0, this is a deadlock situation. To fix the problem, we must break the deadlock, rpcsec_gss_exit_net() should move out of the put() path and find another chance to get called, I think nsfs_evict() is a good place to go, when netns inode gets evicted we call rpcsec_gss_exit_net() to free the rpc client, this requires a new callback i.e. evict to be added in struct proc_ns_operations, and add netns_evict() as one of netns_operations as well. v1->v2: * in nsfs_evict(), move ->evict() in front of ->put() v2->v3: * rpcsec_gss_evict_net() directly call gss_svc_shutdown_net() regardless if gssp_clnt is null, this is exactly same to what rpcsec_gss_exit_net() previously did Wenbin Zeng (3): nsfs: add evict callback into struct proc_ns_operations netns: add netns_evict into netns_operations auth_gss: fix deadlock that blocks rpcsec_gss_exit_net when use-gss-proxy==1 fs/nsfs.c | 2 ++ include/linux/proc_ns.h | 1 + include/net/net_namespace.h | 1 + net/core/net_namespace.c | 12 ++++++++++++ net/sunrpc/auth_gss/auth_gss.c | 4 ++-- 5 files changed, 18 insertions(+), 2 deletions(-)