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block: bdrv_refresh_perms: check for parents permissions conflict

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Add additional check that node parents do not interfere with each
other. This should not hurt existing callers and allows in further
patch use bdrv_refresh_perms() to update a subtree of changed
BdrvChild (check that change is correct).

New check will substitute bdrv_check_update_perm() in following
permissions refactoring, so keep error messages the same to avoid
unit test result changes.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210428151804.439460-10-vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2021-04-28 18:17:37 +03:00 committed by Kevin Wolf
parent 8cad15b156
commit 3bf416ba0f
1 changed files with 54 additions and 9 deletions
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63
block.c
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@ -2026,6 +2026,57 @@ bool bdrv_is_writable(BlockDriverState *bs)
return bdrv_is_writable_after_reopen(bs, NULL);
}
static char *bdrv_child_user_desc(BdrvChild *c)
{
if (c->klass->get_parent_desc) {
return c->klass->get_parent_desc(c);
}
return g_strdup("another user");
}
static bool bdrv_a_allow_b(BdrvChild *a, BdrvChild *b, Error **errp)
{
g_autofree char *user = NULL;
g_autofree char *perm_names = NULL;
if ((b->perm & a->shared_perm) == b->perm) {
return true;
}
perm_names = bdrv_perm_names(b->perm & ~a->shared_perm);
user = bdrv_child_user_desc(a);
error_setg(errp, "Conflicts with use by %s as '%s', which does not "
"allow '%s' on %s",
user, a->name, perm_names, bdrv_get_node_name(b->bs));
return false;
}
static bool bdrv_parent_perms_conflict(BlockDriverState *bs, Error **errp)
{
BdrvChild *a, *b;
/*
* During the loop we'll look at each pair twice. That's correct because
* bdrv_a_allow_b() is asymmetric and we should check each pair in both
* directions.
*/
QLIST_FOREACH(a, &bs->parents, next_parent) {
QLIST_FOREACH(b, &bs->parents, next_parent) {
if (a == b) {
continue;
}
if (!bdrv_a_allow_b(a, b, errp)) {
return true;
}
}
}
return false;
}
static void bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs,
BdrvChild *c, BdrvChildRole role,
BlockReopenQueue *reopen_queue,
@ -2203,15 +2254,6 @@ void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
*shared_perm = cumulative_shared_perms;
}
static char *bdrv_child_user_desc(BdrvChild *c)
{
if (c->klass->get_parent_desc) {
return c->klass->get_parent_desc(c);
}
return g_strdup("another user");
}
char *bdrv_perm_names(uint64_t perm)
{
struct perm_name {
@ -2355,6 +2397,9 @@ static int bdrv_refresh_perms(BlockDriverState *bs, Error **errp)
int ret;
uint64_t perm, shared_perm;
if (bdrv_parent_perms_conflict(bs, errp)) {
return -EPERM;
}
bdrv_get_cumulative_perm(bs, &perm, &shared_perm);
ret = bdrv_check_perm(bs, NULL, perm, shared_perm, NULL, errp);
if (ret < 0) {