Re: [PATCH] vhost-vdpa: honor CAP_IPC_LOCK

On 2021/3/2 5:51 下午, Michael S. Tsirkin wrote:

On Tue, Mar 02, 2021 at 04:14:18AM -0500, Jason Wang wrote:

quoted

When CAP_IPC_LOCK is set we should not check locked memory against
rlimit as what has been implemented in mlock().

Signed-off-by: Jason Wang <redacted>

Indeed and it's not just mlock.

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.

and let's add a Fixes: tag?

Sure, V2 is posted.

Thanks

quoted

---
  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

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