From 91ef38257ad225f7fa17a6583fb792c0be9e8acf Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Tue, 20 Dec 2016 16:23:46 +0100 Subject: [PATCH] vvfat: Implement .bdrv_child_perm() vvfat is the last remaining driver that can have children, but doesn't implement .bdrv_child_perm() yet. The default handlers aren't suitable here, so let's implement a very simple driver-specific one that protects the internal child from being used by other users as good as our permissions permit. Signed-off-by: Kevin Wolf Reviewed-by: Max Reitz Acked-by: Fam Zheng --- block.c | 2 +- block/vvfat.c | 22 ++++++++++++++++++++++ include/block/block_int.h | 1 + 3 files changed, 24 insertions(+), 1 deletion(-) diff --git a/block.c b/block.c index d67819f2a2..281ce7bec3 100644 --- a/block.c +++ b/block.c @@ -823,7 +823,7 @@ static void bdrv_backing_options(int *child_flags, QDict *child_options, *child_flags = flags; } -static const BdrvChildRole child_backing = { +const BdrvChildRole child_backing = { .inherit_options = bdrv_backing_options, .drained_begin = bdrv_child_cb_drained_begin, .drained_end = bdrv_child_cb_drained_end, diff --git a/block/vvfat.c b/block/vvfat.c index 7f230be006..72b482cb1f 100644 --- a/block/vvfat.c +++ b/block/vvfat.c @@ -3052,6 +3052,27 @@ err: return ret; } +static void vvfat_child_perm(BlockDriverState *bs, BdrvChild *c, + const BdrvChildRole *role, + uint64_t perm, uint64_t shared, + uint64_t *nperm, uint64_t *nshared) +{ + BDRVVVFATState *s = bs->opaque; + + assert(c == s->qcow || role == &child_backing); + + if (c == s->qcow) { + /* This is a private node, nobody should try to attach to it */ + *nperm = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE; + *nshared = BLK_PERM_WRITE_UNCHANGED; + } else { + /* The backing file is there so 'commit' can use it. vvfat doesn't + * access it in any way. */ + *nperm = 0; + *nshared = BLK_PERM_ALL; + } +} + static void vvfat_close(BlockDriverState *bs) { BDRVVVFATState *s = bs->opaque; @@ -3077,6 +3098,7 @@ static BlockDriver bdrv_vvfat = { .bdrv_file_open = vvfat_open, .bdrv_refresh_limits = vvfat_refresh_limits, .bdrv_close = vvfat_close, + .bdrv_child_perm = vvfat_child_perm, .bdrv_co_preadv = vvfat_co_preadv, .bdrv_co_pwritev = vvfat_co_pwritev, diff --git a/include/block/block_int.h b/include/block/block_int.h index eb0598e580..63d54460e5 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -466,6 +466,7 @@ struct BdrvChildRole { extern const BdrvChildRole child_file; extern const BdrvChildRole child_format; +extern const BdrvChildRole child_backing; struct BdrvChild { BlockDriverState *bs;