netdev - [PATCH V2] vhost-vdpa: honor CAP_IPC

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Date:   Tue,  2 Mar 2021 05:51:58 -0500
From:   Jason Wang <jasowang@...hat.com>
To:     mst@...hat.com, jasowang@...hat.com, kvm@...r.kernel.org
Cc:     virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH V2] vhost-vdpa: honor CAP_IPC_LOCK

When CAP_IPC_LOCK is set we should not check locked memory against
rlimit as what has been implemented in mlock() and documented in
Documentation/admin-guide/perf-security.rst:

"
RLIMIT_MEMLOCK and perf_event_mlock_kb resource constraints are ignored
for processes with the CAP_IPC_LOCK capability.
"

Fixes: 4c8cf31885f6 ("vhost: introduce vDPA-based backend")
Signed-off-by: Jason Wang <jasowang@...hat.com>
---
 drivers/vhost/vdpa.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index ef688c8c0e0e..e93572e2e344 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -638,7 +638,8 @@ static int vhost_vdpa_process_iotlb_update(struct vhost_vdpa *v,
 	mmap_read_lock(dev->mm);
 
 	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
-	if (npages + atomic64_read(&dev->mm->pinned_vm) > lock_limit) {
+	if (!capable(CAP_IPC_LOCK) &&
+	    (npages + atomic64_read(&dev->mm->pinned_vm) > lock_limit)) {
 		ret = -ENOMEM;
 		goto unlock;
 	}
-- 
2.18.1