linux-stable.git/fs/lockd, branch v4.16 Linux kernel stable tree lockd: Fix server refcounting 2018-01-24T22:33:57+00:00 Trond Myklebust trondmy@gmail.com 2018-01-24T00:39:04+00:00 535cb8f3193f2976f39371810dcad64ae2650771 The server shouldn't actually delete the struct nlm_host until it hits the garbage collector. In order to make that work correctly with the refcount API, we can bump the refcount by one, and then use refcount_dec_if_one() in the garbage collector. Signed-off-by: Trond Myklebust <trondmy@gmail.com> Acked-by: J. Bruce Fields <bfields@fieldses.org> 
The server shouldn't actually delete the struct nlm_host until it hits
the garbage collector. In order to make that work correctly with the
refcount API, we can bump the refcount by one, and then use
refcount_dec_if_one() in the garbage collector.

Signed-off-by: Trond Myklebust <trondmy@gmail.com>
Acked-by: J. Bruce Fields <bfields@fieldses.org>
lockd: convert nlm_rqst.a_count from atomic_t to refcount_t 2018-01-15T04:06:30+00:00 Elena Reshetova elena.reshetova@intel.com 2017-11-29T11:15:46+00:00 fbca30c51350399f49b09421b5ee2ef8d00c05d8 atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable nlm_rqst.a_count is used as pure reference counter. Convert it to refcount_t and fix up the operations. **Important note for maintainers: Some functions from refcount_t API defined in lib/refcount.c have different memory ordering guarantees than their atomic counterparts. The full comparison can be seen in https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon in state to be merged to the documentation tree. Normally the differences should not matter since refcount_t provides enough guarantees to satisfy the refcounting use cases, but in some rare cases it might matter. Please double check that you don't have some undocumented memory guarantees for this variable usage. For the nlm_rqst.a_count it might make a difference in following places: - nlmclnt_release_call() and nlmsvc_release_call(): decrement in refcount_dec_and_test() only provides RELEASE ordering and control dependency on success vs. fully ordered atomic counterpart Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> 
atomic_t variables are currently used to implement reference
counters with the following properties:
 - counter is initialized to 1 using atomic_set()
 - a resource is freed upon counter reaching zero
 - once counter reaches zero, its further
   increments aren't allowed
 - counter schema uses basic atomic operations
   (set, inc, inc_not_zero, dec_and_test, etc.)

Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.

The variable nlm_rqst.a_count is used as pure reference counter.
Convert it to refcount_t and fix up the operations.

**Important note for maintainers:

Some functions from refcount_t API defined in lib/refcount.c
have different memory ordering guarantees than their atomic
counterparts.
The full comparison can be seen in
https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon
in state to be merged to the documentation tree.
Normally the differences should not matter since refcount_t provides
enough guarantees to satisfy the refcounting use cases, but in
some rare cases it might matter.
Please double check that you don't have some undocumented
memory guarantees for this variable usage.

For the nlm_rqst.a_count it might make a difference
in following places:
 - nlmclnt_release_call() and nlmsvc_release_call(): decrement
   in refcount_dec_and_test() only
   provides RELEASE ordering and control dependency on success
   vs. fully ordered atomic counterpart

Suggested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
lockd: convert nlm_lockowner.count from atomic_t to refcount_t 2018-01-15T04:06:29+00:00 Elena Reshetova elena.reshetova@intel.com 2017-11-29T11:15:45+00:00 431f125b67d51a84b93095a7df6b3c30222753b1 atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable nlm_lockowner.count is used as pure reference counter. Convert it to refcount_t and fix up the operations. **Important note for maintainers: Some functions from refcount_t API defined in lib/refcount.c have different memory ordering guarantees than their atomic counterparts. The full comparison can be seen in https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon in state to be merged to the documentation tree. Normally the differences should not matter since refcount_t provides enough guarantees to satisfy the refcounting use cases, but in some rare cases it might matter. Please double check that you don't have some undocumented memory guarantees for this variable usage. For the nlm_lockowner.count it might make a difference in following places: - nlm_put_lockowner(): decrement in refcount_dec_and_lock() only provides RELEASE ordering, control dependency on success and holds a spin lock on success vs. fully ordered atomic counterpart. No changes in spin lock guarantees. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> 
atomic_t variables are currently used to implement reference
counters with the following properties:
 - counter is initialized to 1 using atomic_set()
 - a resource is freed upon counter reaching zero
 - once counter reaches zero, its further
   increments aren't allowed
 - counter schema uses basic atomic operations
   (set, inc, inc_not_zero, dec_and_test, etc.)

Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.

The variable nlm_lockowner.count is used as pure reference counter.
Convert it to refcount_t and fix up the operations.

**Important note for maintainers:

Some functions from refcount_t API defined in lib/refcount.c
have different memory ordering guarantees than their atomic
counterparts.
The full comparison can be seen in
https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon
in state to be merged to the documentation tree.
Normally the differences should not matter since refcount_t provides
enough guarantees to satisfy the refcounting use cases, but in
some rare cases it might matter.
Please double check that you don't have some undocumented
memory guarantees for this variable usage.

For the nlm_lockowner.count it might make a difference
in following places:
 - nlm_put_lockowner(): decrement in refcount_dec_and_lock() only
   provides RELEASE ordering, control dependency on success and
   holds a spin lock on success vs. fully ordered atomic counterpart.
   No changes in spin lock guarantees.

Suggested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
lockd: convert nsm_handle.sm_count from atomic_t to refcount_t 2018-01-15T04:06:29+00:00 Elena Reshetova elena.reshetova@intel.com 2017-11-29T11:15:44+00:00 c751082ceff7d5907f436729dd7cccb88cffc4de atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable nsm_handle.sm_count is used as pure reference counter. Convert it to refcount_t and fix up the operations. **Important note for maintainers: Some functions from refcount_t API defined in lib/refcount.c have different memory ordering guarantees than their atomic counterparts. The full comparison can be seen in https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon in state to be merged to the documentation tree. Normally the differences should not matter since refcount_t provides enough guarantees to satisfy the refcounting use cases, but in some rare cases it might matter. Please double check that you don't have some undocumented memory guarantees for this variable usage. For the nsm_handle.sm_count it might make a difference in following places: - nsm_release(): decrement in refcount_dec_and_lock() only provides RELEASE ordering, control dependency on success and holds a spin lock on success vs. fully ordered atomic counterpart. No change for the spin lock guarantees. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> 
atomic_t variables are currently used to implement reference
counters with the following properties:
 - counter is initialized to 1 using atomic_set()
 - a resource is freed upon counter reaching zero
 - once counter reaches zero, its further
   increments aren't allowed
 - counter schema uses basic atomic operations
   (set, inc, inc_not_zero, dec_and_test, etc.)

Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.

The variable nsm_handle.sm_count is used as pure reference counter.
Convert it to refcount_t and fix up the operations.

**Important note for maintainers:

Some functions from refcount_t API defined in lib/refcount.c
have different memory ordering guarantees than their atomic
counterparts.
The full comparison can be seen in
https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon
in state to be merged to the documentation tree.
Normally the differences should not matter since refcount_t provides
enough guarantees to satisfy the refcounting use cases, but in
some rare cases it might matter.
Please double check that you don't have some undocumented
memory guarantees for this variable usage.

For the nsm_handle.sm_count it might make a difference
in following places:
 - nsm_release(): decrement in refcount_dec_and_lock() only
   provides RELEASE ordering, control dependency on success
   and holds a spin lock on success vs. fully ordered atomic
   counterpart. No change for the spin lock guarantees.

Suggested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
lockd: convert nlm_host.h_count from atomic_t to refcount_t 2018-01-15T04:06:29+00:00 Elena Reshetova elena.reshetova@intel.com 2017-11-29T11:15:43+00:00 fee21fb587f57748c3c971e3432c4a28d74146fc atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable nlm_host.h_count is used as pure reference counter. Convert it to refcount_t and fix up the operations. **Important note for maintainers: Some functions from refcount_t API defined in lib/refcount.c have different memory ordering guarantees than their atomic counterparts. The full comparison can be seen in https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon in state to be merged to the documentation tree. Normally the differences should not matter since refcount_t provides enough guarantees to satisfy the refcounting use cases, but in some rare cases it might matter. Please double check that you don't have some undocumented memory guarantees for this variable usage. For the nlm_host.h_count it might make a difference in following places: - nlmsvc_release_host(): decrement in refcount_dec() provides RELEASE ordering, while original atomic_dec() was fully unordered. Since the change is for better, it should not matter. - nlmclnt_release_host(): decrement in refcount_dec_and_test() only provides RELEASE ordering and control dependency on success vs. fully ordered atomic counterpart. It doesn't seem to matter in this case since object freeing happens under mutex lock anyway. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> 
atomic_t variables are currently used to implement reference
counters with the following properties:
 - counter is initialized to 1 using atomic_set()
 - a resource is freed upon counter reaching zero
 - once counter reaches zero, its further
   increments aren't allowed
 - counter schema uses basic atomic operations
   (set, inc, inc_not_zero, dec_and_test, etc.)

Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.

The variable nlm_host.h_count  is used as pure reference counter.
Convert it to refcount_t and fix up the operations.

**Important note for maintainers:

Some functions from refcount_t API defined in lib/refcount.c
have different memory ordering guarantees than their atomic
counterparts.
The full comparison can be seen in
https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon
in state to be merged to the documentation tree.
Normally the differences should not matter since refcount_t provides
enough guarantees to satisfy the refcounting use cases, but in
some rare cases it might matter.
Please double check that you don't have some undocumented
memory guarantees for this variable usage.

For the nlm_host.h_count it might make a difference
in following places:
 - nlmsvc_release_host(): decrement in refcount_dec()
   provides RELEASE ordering, while original atomic_dec()
   was fully unordered. Since the change is for better, it
   should not matter.
 - nlmclnt_release_host(): decrement in refcount_dec_and_test() only
   provides RELEASE ordering and control dependency on success
   vs. fully ordered atomic counterpart. It doesn't seem to
   matter in this case since object freeing happens under mutex
   lock anyway.

Suggested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
nlm_shutdown_hosts_net() cleanup 2017-11-27T21:45:11+00:00 Vasily Averin vvs@virtuozzo.com 2017-10-30T13:47:58+00:00 9e137ed5abcb21c0efffb1b6a7c48f2d21980303 nlm_complain_hosts() walks through nlm_server_hosts hlist, which should be protected by nlm_host_mutex. Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> 
nlm_complain_hosts() walks through nlm_server_hosts hlist, which should
be protected by nlm_host_mutex.

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
race of lockd inetaddr notifiers vs nlmsvc_rqst change 2017-11-27T21:45:11+00:00 Vasily Averin vvs@virtuozzo.com 2017-11-10T07:19:26+00:00 6b18dd1c03e07262ea0866084856b2a3c5ba8d09 lockd_inet[6]addr_event use nlmsvc_rqst without taken nlmsvc_mutex, nlmsvc_rqst can be changed during execution of notifiers and crash the host. Patch enables access to nlmsvc_rqst only when it was correctly initialized and delays its cleanup until notifiers are no longer in use. Note that nlmsvc_rqst can be temporally set to ERR_PTR, so the "if (nlmsvc_rqst)" check in notifiers is insufficient on its own. Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Tested-by: Scott Mayhew <smayhew@redhat.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> 
lockd_inet[6]addr_event use nlmsvc_rqst without taken nlmsvc_mutex,
nlmsvc_rqst can be changed during execution of notifiers and crash the host.

Patch enables access to nlmsvc_rqst only when it was correctly initialized
and delays its cleanup until notifiers are no longer in use.

Note that nlmsvc_rqst can be temporally set to ERR_PTR, so the "if
(nlmsvc_rqst)" check in notifiers is insufficient on its own.

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Tested-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
lockd: lost rollback of set_grace_period() in lockd_down_net() 2017-11-27T21:45:11+00:00 Vasily Averin vvs@virtuozzo.com 2017-11-02T10:03:42+00:00 3a2b19d1ee5633f76ae8a88da7bc039a5d1732aa Commit efda760fe95ea ("lockd: fix lockd shutdown race") is incorrect, it removes lockd_manager and disarm grace_period_end for init_net only. If nfsd was started from another net namespace lockd_up_net() calls set_grace_period() that adds lockd_manager into per-netns list and queues grace_period_end delayed work. These action should be reverted in lockd_down_net(). Otherwise it can lead to double list_add on after restart nfsd in netns, and to use-after-free if non-disarmed delayed work will be executed after netns destroy. Fixes: efda760fe95e ("lockd: fix lockd shutdown race") Cc: stable@vger.kernel.org Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> 
Commit efda760fe95ea ("lockd: fix lockd shutdown race") is incorrect,
it removes lockd_manager and disarm grace_period_end for init_net only.

If nfsd was started from another net namespace lockd_up_net() calls
set_grace_period() that adds lockd_manager into per-netns list
and queues grace_period_end delayed work.

These action should be reverted in lockd_down_net().
Otherwise it can lead to double list_add on after restart nfsd in netns,
and to use-after-free if non-disarmed delayed work will be executed after netns destroy.

Fixes: efda760fe95e ("lockd: fix lockd shutdown race")
Cc: stable@vger.kernel.org
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
lockd: added cleanup checks in exit_net hook 2017-11-27T21:45:10+00:00 Vasily Averin vvs@virtuozzo.com 2017-11-06T13:23:24+00:00 a3152f1440c762128a626d90718ba6535c81c1b4 Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> 
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
lockd: remove net pointer from messages 2017-11-27T21:45:10+00:00 Vasily Averin vvs@virtuozzo.com 2017-11-08T05:55:55+00:00 e919b0765287f36f7e9c84aed785eddfbbd98dfa Publishing of net pointer is not safe, use net->ns.inum as net ID in debug messages [ 171.757678] lockd_up_net: per-net data created; net=f00001e7 [ 171.767188] NFSD: starting 90-second grace period (net f00001e7) [ 300.653313] lockd: nuking all hosts in net f00001e7... [ 300.653641] lockd: host garbage collection for net f00001e7 [ 300.653968] lockd: nlmsvc_mark_resources for net f00001e7 [ 300.711483] lockd_down_net: per-net data destroyed; net=f00001e7 [ 300.711847] lockd: nuking all hosts in net 0... [ 300.711847] lockd: host garbage collection for net 0 [ 300.711848] lockd: nlmsvc_mark_resources for net 0 Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> 
Publishing of net pointer is not safe,
use net->ns.inum as net ID in debug messages

[  171.757678] lockd_up_net: per-net data created; net=f00001e7
[  171.767188] NFSD: starting 90-second grace period (net f00001e7)
[  300.653313] lockd: nuking all hosts in net f00001e7...
[  300.653641] lockd: host garbage collection for net f00001e7
[  300.653968] lockd: nlmsvc_mark_resources for net f00001e7
[  300.711483] lockd_down_net: per-net data destroyed; net=f00001e7
[  300.711847] lockd: nuking all hosts in net 0...
[  300.711847] lockd: host garbage collection for net 0
[  300.711848] lockd: nlmsvc_mark_resources for net 0

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>