[qemu-xen staging] block/crypto: disallow write sharing by default

[patchbot@xxxxxxx]

commit 662d0c5392a272aa0357aa7205e77fa3ca89c316
Author:     Maxim Levitsky <mlevitsk@xxxxxxxxxx>
AuthorDate: Sun Jul 19 15:20:58 2020 +0300
Commit:     Max Reitz <mreitz@xxxxxxxxxx>
CommitDate: Tue Jul 21 10:49:02 2020 +0200

    block/crypto: disallow write sharing by default
    
    My commit 'block/crypto: implement the encryption key management'
    accidently allowed raw luks images to be shared between different
    qemu processes without share-rw=on explicit override.
    Fix that.
    
    Fixes: bbfdae91fb ("block/crypto: implement the encryption key management")
    Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1857490
    
    Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
    Message-Id: <20200719122059.59843-2-mlevitsk@xxxxxxxxxx>
    Signed-off-by: Max Reitz <mreitz@xxxxxxxxxx>
---
 block/crypto.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/crypto.c b/block/crypto.c
index 8725c1bc02..0807557763 100644
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -881,7 +881,7 @@ block_crypto_child_perms(BlockDriverState *bs, BdrvChild *c,
      * For backward compatibility, manually share the write
      * and resize permission
      */
-    *nshared |= (BLK_PERM_WRITE | BLK_PERM_RESIZE);
+    *nshared |= shared & (BLK_PERM_WRITE | BLK_PERM_RESIZE);
     /*
      * Since we are not fully a format driver, don't always request
      * the read/resize permission but only when explicitly
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#staging