From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 23F09C31E5E for ; Tue, 18 Jun 2019 16:24:46 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E208A2054F for ; Tue, 18 Jun 2019 16:24:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E208A2054F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:59532 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hdGub-0003A2-6z for qemu-devel@archiver.kernel.org; Tue, 18 Jun 2019 12:24:45 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56327) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hdFxm-0008Sr-Nt for qemu-devel@nongnu.org; Tue, 18 Jun 2019 11:24:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hdFxd-0000v6-B7 for qemu-devel@nongnu.org; Tue, 18 Jun 2019 11:23:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41714) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hdFxS-0000hH-QB; Tue, 18 Jun 2019 11:23:39 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2368A30BB524; Tue, 18 Jun 2019 15:23:37 +0000 (UTC) Received: from localhost.localdomain.com (ovpn-116-185.ams2.redhat.com [10.36.116.185]) by smtp.corp.redhat.com (Postfix) with ESMTP id 43AD519492; Tue, 18 Jun 2019 15:23:36 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Date: Tue, 18 Jun 2019 17:23:15 +0200 Message-Id: <20190618152318.24953-12-kwolf@redhat.com> In-Reply-To: <20190618152318.24953-1-kwolf@redhat.com> References: <20190618152318.24953-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Tue, 18 Jun 2019 15:23:37 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 11/14] block: Add *tighten_restrictions to *check*_perm() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Max Reitz This patch makes three functions report whether the necessary permission change tightens restrictions or not. These functions are: - bdrv_check_perm() - bdrv_check_update_perm() - bdrv_child_check_perm() Callers can use this result to decide whether a failure is fatal or not (see the next patch). Signed-off-by: Max Reitz Signed-off-by: Kevin Wolf --- block.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 70 insertions(+), 17 deletions(-) diff --git a/block.c b/block.c index b7d4149c2f..1b10a5ce35 100644 --- a/block.c +++ b/block.c @@ -1706,7 +1706,8 @@ static int bdrv_fill_options(QDict **options, const= char *filename, =20 static int bdrv_child_check_perm(BdrvChild *c, BlockReopenQueue *q, uint64_t perm, uint64_t shared, - GSList *ignore_children, Error **errp); + GSList *ignore_children, + bool *tighten_restrictions, Error **err= p); static void bdrv_child_abort_perm_update(BdrvChild *c); static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm, uint64_t sh= ared); static void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *per= m, @@ -1781,18 +1782,43 @@ static void bdrv_child_perm(BlockDriverState *bs,= BlockDriverState *child_bs, * permissions of all its parents. This involves checking whether all ne= cessary * permission changes to child nodes can be performed. * + * Will set *tighten_restrictions to true if and only if new permissions= have to + * be taken or currently shared permissions are to be unshared. Otherwi= se, + * errors are not fatal as long as the caller accepts that the restricti= ons + * remain tighter than they need to be. The caller still has to abort t= he + * transaction. + * @tighten_restrictions cannot be used together with @q: When reopening= , we may + * encounter fatal errors even though no restrictions are to be tightene= d. For + * example, changing a node from RW to RO will fail if the WRITE permiss= ion is + * to be kept. + * * A call to this function must always be followed by a call to bdrv_set= _perm() * or bdrv_abort_perm_update(). */ static int bdrv_check_perm(BlockDriverState *bs, BlockReopenQueue *q, uint64_t cumulative_perms, uint64_t cumulative_shared_perms, - GSList *ignore_children, Error **errp) + GSList *ignore_children, + bool *tighten_restrictions, Error **errp) { BlockDriver *drv =3D bs->drv; BdrvChild *c; int ret; =20 + assert(!q || !tighten_restrictions); + + if (tighten_restrictions) { + uint64_t current_perms, current_shared; + uint64_t added_perms, removed_shared_perms; + + bdrv_get_cumulative_perm(bs, ¤t_perms, ¤t_shared); + + added_perms =3D cumulative_perms & ~current_perms; + removed_shared_perms =3D current_shared & ~cumulative_shared_per= ms; + + *tighten_restrictions =3D added_perms || removed_shared_perms; + } + /* Write permissions never work with read-only images */ if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED))= && !bdrv_is_writable_after_reopen(bs, q)) @@ -1833,11 +1859,18 @@ static int bdrv_check_perm(BlockDriverState *bs, = BlockReopenQueue *q, /* Check all children */ QLIST_FOREACH(c, &bs->children, next) { uint64_t cur_perm, cur_shared; + bool child_tighten_restr; + bdrv_child_perm(bs, c->bs, c, c->role, q, cumulative_perms, cumulative_shared_perms, &cur_perm, &cur_shared); - ret =3D bdrv_child_check_perm(c, q, cur_perm, cur_shared, - ignore_children, errp); + ret =3D bdrv_child_check_perm(c, q, cur_perm, cur_shared, ignore= _children, + tighten_restrictions ? &child_tighte= n_restr + : NULL, + errp); + if (tighten_restrictions) { + *tighten_restrictions |=3D child_tighten_restr; + } if (ret < 0) { return ret; } @@ -1961,17 +1994,23 @@ char *bdrv_perm_names(uint64_t perm) * set, the BdrvChild objects in this list are ignored in the calculatio= ns; * this allows checking permission updates for an existing reference. * + * See bdrv_check_perm() for the semantics of @tighten_restrictions. + * * Needs to be followed by a call to either bdrv_set_perm() or * bdrv_abort_perm_update(). */ static int bdrv_check_update_perm(BlockDriverState *bs, BlockReopenQueue= *q, uint64_t new_used_perm, uint64_t new_shared_perm, - GSList *ignore_children, Error **errp) + GSList *ignore_children, + bool *tighten_restrictions, + Error **errp) { BdrvChild *c; uint64_t cumulative_perms =3D new_used_perm; uint64_t cumulative_shared_perms =3D new_shared_perm; =20 + assert(!q || !tighten_restrictions); + /* There is no reason why anyone couldn't tolerate write_unchanged *= / assert(new_shared_perm & BLK_PERM_WRITE_UNCHANGED); =20 @@ -1983,6 +2022,11 @@ static int bdrv_check_update_perm(BlockDriverState= *bs, BlockReopenQueue *q, if ((new_used_perm & c->shared_perm) !=3D new_used_perm) { char *user =3D bdrv_child_user_desc(c); char *perm_names =3D bdrv_perm_names(new_used_perm & ~c->sha= red_perm); + + if (tighten_restrictions) { + *tighten_restrictions =3D true; + } + error_setg(errp, "Conflicts with use by %s as '%s', which do= es not " "allow '%s' on %s", user, c->name, perm_names, bdrv_get_node_name(c->= bs)); @@ -1994,6 +2038,11 @@ static int bdrv_check_update_perm(BlockDriverState= *bs, BlockReopenQueue *q, if ((c->perm & new_shared_perm) !=3D c->perm) { char *user =3D bdrv_child_user_desc(c); char *perm_names =3D bdrv_perm_names(c->perm & ~new_shared_p= erm); + + if (tighten_restrictions) { + *tighten_restrictions =3D true; + } + error_setg(errp, "Conflicts with use by %s as '%s', which us= es " "'%s' on %s", user, c->name, perm_names, bdrv_get_node_name(c->= bs)); @@ -2007,19 +2056,21 @@ static int bdrv_check_update_perm(BlockDriverStat= e *bs, BlockReopenQueue *q, } =20 return bdrv_check_perm(bs, q, cumulative_perms, cumulative_shared_pe= rms, - ignore_children, errp); + ignore_children, tighten_restrictions, errp); } =20 /* Needs to be followed by a call to either bdrv_child_set_perm() or * bdrv_child_abort_perm_update(). */ static int bdrv_child_check_perm(BdrvChild *c, BlockReopenQueue *q, uint64_t perm, uint64_t shared, - GSList *ignore_children, Error **errp) + GSList *ignore_children, + bool *tighten_restrictions, Error **err= p) { int ret; =20 ignore_children =3D g_slist_prepend(g_slist_copy(ignore_children), c= ); - ret =3D bdrv_check_update_perm(c->bs, q, perm, shared, ignore_childr= en, errp); + ret =3D bdrv_check_update_perm(c->bs, q, perm, shared, ignore_childr= en, + tighten_restrictions, errp); g_slist_free(ignore_children); =20 if (ret < 0) { @@ -2072,7 +2123,7 @@ int bdrv_child_try_set_perm(BdrvChild *c, uint64_t = perm, uint64_t shared, { int ret; =20 - ret =3D bdrv_child_check_perm(c, NULL, perm, shared, NULL, errp); + ret =3D bdrv_child_check_perm(c, NULL, perm, shared, NULL, NULL, err= p); if (ret < 0) { bdrv_child_abort_perm_update(c); return ret; @@ -2258,7 +2309,8 @@ static void bdrv_replace_child(BdrvChild *child, Bl= ockDriverState *new_bs) * because we're just taking a parent away, so we're loosening * restrictions. */ bdrv_get_cumulative_perm(old_bs, &perm, &shared_perm); - bdrv_check_perm(old_bs, NULL, perm, shared_perm, NULL, &error_ab= ort); + bdrv_check_perm(old_bs, NULL, perm, shared_perm, NULL, + NULL, &error_abort); bdrv_set_perm(old_bs, perm, shared_perm); =20 /* When the parent requiring a non-default AioContext is removed= , the @@ -2288,7 +2340,8 @@ BdrvChild *bdrv_root_attach_child(BlockDriverState = *child_bs, Error *local_err =3D NULL; int ret; =20 - ret =3D bdrv_check_update_perm(child_bs, NULL, perm, shared_perm, NU= LL, errp); + ret =3D bdrv_check_update_perm(child_bs, NULL, perm, shared_perm, NU= LL, NULL, + errp); if (ret < 0) { bdrv_abort_perm_update(child_bs); bdrv_unref(child_bs); @@ -3369,7 +3422,7 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue= , Error **errp) QSIMPLEQ_FOREACH(bs_entry, bs_queue, entry) { BDRVReopenState *state =3D &bs_entry->state; ret =3D bdrv_check_perm(state->bs, bs_queue, state->perm, - state->shared_perm, NULL, errp); + state->shared_perm, NULL, NULL, errp); if (ret < 0) { goto cleanup_perm; } @@ -3381,7 +3434,7 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue= , Error **errp) state->perm, state->shared_perm, &nperm, &nshared); ret =3D bdrv_check_update_perm(state->new_backing_bs, NULL, - nperm, nshared, NULL, errp); + nperm, nshared, NULL, NULL, err= p); if (ret < 0) { goto cleanup_perm; } @@ -4097,7 +4150,7 @@ void bdrv_replace_node(BlockDriverState *from, Bloc= kDriverState *to, =20 /* Check whether the required permissions can be granted on @to, ign= oring * all BdrvChild in @list so that they can't block themselves. */ - ret =3D bdrv_check_update_perm(to, NULL, perm, shared, list, errp); + ret =3D bdrv_check_update_perm(to, NULL, perm, shared, list, NULL, e= rrp); if (ret < 0) { bdrv_abort_perm_update(to); goto out; @@ -4444,7 +4497,7 @@ int bdrv_drop_intermediate(BlockDriverState *top, B= lockDriverState *base, /* Check whether we are allowed to switch c from top to base */ GSList *ignore_children =3D g_slist_prepend(NULL, c); ret =3D bdrv_check_update_perm(base, NULL, c->perm, c->shared_pe= rm, - ignore_children, &local_err); + ignore_children, NULL, &local_err); g_slist_free(ignore_children); if (ret < 0) { error_report_err(local_err); @@ -5219,7 +5272,7 @@ static void coroutine_fn bdrv_co_invalidate_cache(B= lockDriverState *bs, */ bs->open_flags &=3D ~BDRV_O_INACTIVE; bdrv_get_cumulative_perm(bs, &perm, &shared_perm); - ret =3D bdrv_check_perm(bs, NULL, perm, shared_perm, NULL, &local_er= r); + ret =3D bdrv_check_perm(bs, NULL, perm, shared_perm, NULL, NULL, &lo= cal_err); if (ret < 0) { bs->open_flags |=3D BDRV_O_INACTIVE; error_propagate(errp, local_err); @@ -5369,7 +5422,7 @@ static int bdrv_inactivate_recurse(BlockDriverState= *bs) =20 /* Update permissions, they may differ for inactive nodes */ bdrv_get_cumulative_perm(bs, &perm, &shared_perm); - bdrv_check_perm(bs, NULL, perm, shared_perm, NULL, &error_abort); + bdrv_check_perm(bs, NULL, perm, shared_perm, NULL, NULL, &error_abor= t); bdrv_set_perm(bs, perm, shared_perm); =20 =20 --=20 2.20.1