| Message ID | 1487006583-24350-12-git-send-email-kwolf@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 13.02.2017 18:22, Kevin Wolf wrote: > 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 <kwolf@redhat.com> > --- > block/vvfat.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/block/vvfat.c b/block/vvfat.c > index c6bf67e..7246432 100644 > --- a/block/vvfat.c > +++ b/block/vvfat.c > @@ -3052,6 +3052,18 @@ 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) > +{ > + assert(role == &child_vvfat_qcow); > + > + /* This is a private node, nobody should try to attach to it */ > + *nperm = BLK_PERM_WRITE; > + *nshared = 0; 0 for shared is probably enough to ward every other access off, but maybe we should still pro forma request consistent read access...? Max > +} > + > static void vvfat_close(BlockDriverState *bs) > { > BDRVVVFATState *s = bs->opaque; > @@ -3077,6 +3089,7 @@ 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, >
Am 15.02.2017 um 18:30 hat Max Reitz geschrieben: > On 13.02.2017 18:22, Kevin Wolf wrote: > > 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 <kwolf@redhat.com> > > --- > > block/vvfat.c | 13 +++++++++++++ > > 1 file changed, 13 insertions(+) > > > > diff --git a/block/vvfat.c b/block/vvfat.c > > index c6bf67e..7246432 100644 > > --- a/block/vvfat.c > > +++ b/block/vvfat.c > > @@ -3052,6 +3052,18 @@ 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) > > +{ > > + assert(role == &child_vvfat_qcow); > > + > > + /* This is a private node, nobody should try to attach to it */ > > + *nperm = BLK_PERM_WRITE; > > + *nshared = 0; > > 0 for shared is probably enough to ward every other access off, but > maybe we should still pro forma request consistent read access...? Makes sense, yes. But you missed the real bug I hid there for you: qemu-system-x86_64: block.c:1530: bdrv_check_update_perm: Assertion `new_shared_perm & BLK_PERM_WRITE_UNCHANGED' failed. Kevin > Max > > > +} > > + > > static void vvfat_close(BlockDriverState *bs) > > { > > BDRVVVFATState *s = bs->opaque; > > @@ -3077,6 +3089,7 @@ 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/block/vvfat.c b/block/vvfat.c index c6bf67e..7246432 100644 --- a/block/vvfat.c +++ b/block/vvfat.c @@ -3052,6 +3052,18 @@ 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) +{ + assert(role == &child_vvfat_qcow); + + /* This is a private node, nobody should try to attach to it */ + *nperm = BLK_PERM_WRITE; + *nshared = 0; +} + static void vvfat_close(BlockDriverState *bs) { BDRVVVFATState *s = bs->opaque; @@ -3077,6 +3089,7 @@ 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,
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 <kwolf@redhat.com> --- block/vvfat.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)