From nobody Sun Apr 13 04:29:57 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1488315715568862.5906655688069; Tue, 28 Feb 2017 13:01:55 -0800 (PST) Received: from localhost ([::1]:36895 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ciouA-0001XT-8j for importer@patchew.org; Tue, 28 Feb 2017 16:01:54 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45651) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cioXB-0006cg-Bg for qemu-devel@nongnu.org; Tue, 28 Feb 2017 15:38:12 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cioX9-00085u-Up for qemu-devel@nongnu.org; Tue, 28 Feb 2017 15:38:09 -0500 Received: from mx1.redhat.com ([209.132.183.28]:23581) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cioX6-00083y-Lv; Tue, 28 Feb 2017 15:38:04 -0500 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CABA33B71B; Tue, 28 Feb 2017 20:38:04 +0000 (UTC) Received: from noname.redhat.com (ovpn-116-177.ams2.redhat.com [10.36.116.177]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id v1SKapFd021888; Tue, 28 Feb 2017 15:38:03 -0500 From: Kevin Wolf To: qemu-block@nongnu.org Date: Tue, 28 Feb 2017 21:36:37 +0100 Message-Id: <1488314205-16264-39-git-send-email-kwolf@redhat.com> In-Reply-To: <1488314205-16264-1-git-send-email-kwolf@redhat.com> References: <1488314205-16264-1-git-send-email-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Tue, 28 Feb 2017 20:38:04 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 38/46] hmp: Request permissions in qemu-io X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 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+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" The HMP command 'qemu-io' is a bit tricky because it wants to work on the original BlockBackend, but additional permissions could be required. The details are explained in a comment in the code, but in summary, just request whatever permissions the current qemu-io command needs. Signed-off-by: Kevin Wolf Reviewed-by: Max Reitz Acked-by: Fam Zheng --- block/block-backend.c | 6 ++++++ hmp.c | 26 +++++++++++++++++++++++++- include/qemu-io.h | 1 + include/sysemu/block-backend.h | 1 + qemu-io-cmds.c | 28 ++++++++++++++++++++++++++++ 5 files changed, 61 insertions(+), 1 deletion(-) diff --git a/block/block-backend.c b/block/block-backend.c index 38a3858..daa7908 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -584,6 +584,12 @@ int blk_set_perm(BlockBackend *blk, uint64_t perm, uin= t64_t shared_perm, return 0; } =20 +void blk_get_perm(BlockBackend *blk, uint64_t *perm, uint64_t *shared_perm) +{ + *perm =3D blk->perm; + *shared_perm =3D blk->shared_perm; +} + static int blk_do_attach_dev(BlockBackend *blk, void *dev) { if (blk->dev) { diff --git a/hmp.c b/hmp.c index e219f97..7b44e64 100644 --- a/hmp.c +++ b/hmp.c @@ -2051,7 +2051,6 @@ void hmp_qemu_io(Monitor *mon, const QDict *qdict) if (!blk) { BlockDriverState *bs =3D bdrv_lookup_bs(NULL, device, &err); if (bs) { - /* FIXME Use real permissions */ blk =3D local_blk =3D blk_new(0, BLK_PERM_ALL); ret =3D blk_insert_bs(blk, bs, &err); if (ret < 0) { @@ -2065,6 +2064,31 @@ void hmp_qemu_io(Monitor *mon, const QDict *qdict) aio_context =3D blk_get_aio_context(blk); aio_context_acquire(aio_context); =20 + /* + * Notably absent: Proper permission management. This is sad, but it s= eems + * almost impossible to achieve without changing the semantics and the= reby + * limiting the use cases of the qemu-io HMP command. + * + * In an ideal world we would unconditionally create a new BlockBacken= d for + * qemuio_command(), but we have commands like 'reopen' and want them = to + * take effect on the exact BlockBackend whose name the user passed in= stead + * of just on a temporary copy of it. + * + * Another problem is that deleting the temporary BlockBackend involves + * draining all requests on it first, but some qemu-iotests cases want= to + * issue multiple aio_read/write requests and expect them to complete = in + * the background while the monitor has already returned. + * + * This is also what prevents us from saving the original permissions = and + * restoring them later: We can't revoke permissions until all requests + * have completed, and we don't know when that is nor can we really let + * anything else run before we have revoken them to avoid race conditi= ons. + * + * What happens now is that command() in qemu-io-cmds.c can extend the + * permissions if necessary for the qemu-io command. And they simply s= tay + * extended, possibly resulting in a read-only guest device keeping wr= ite + * permissions. Ugly, but it appears to be the lesser evil. + */ qemuio_command(blk, command); =20 aio_context_release(aio_context); diff --git a/include/qemu-io.h b/include/qemu-io.h index 4d402b9..196fde0 100644 --- a/include/qemu-io.h +++ b/include/qemu-io.h @@ -36,6 +36,7 @@ typedef struct cmdinfo { const char *args; const char *oneline; helpfunc_t help; + uint64_t perm; } cmdinfo_t; =20 extern bool qemuio_misalign; diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h index b23f683..096c17f 100644 --- a/include/sysemu/block-backend.h +++ b/include/sysemu/block-backend.h @@ -107,6 +107,7 @@ bool bdrv_has_blk(BlockDriverState *bs); bool bdrv_is_root_node(BlockDriverState *bs); int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm, Error **errp); +void blk_get_perm(BlockBackend *blk, uint64_t *perm, uint64_t *shared_perm= ); =20 void blk_set_allow_write_beyond_eof(BlockBackend *blk, bool allow); void blk_iostatus_enable(BlockBackend *blk); diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c index 7ac1576..2c48f9c 100644 --- a/qemu-io-cmds.c +++ b/qemu-io-cmds.c @@ -83,6 +83,29 @@ static int command(BlockBackend *blk, const cmdinfo_t *c= t, int argc, } return 0; } + + /* Request additional permissions if necessary for this command. The c= aller + * is responsible for restoring the original permissions afterwards if= this + * is what it wants. */ + if (ct->perm && blk_is_available(blk)) { + uint64_t orig_perm, orig_shared_perm; + blk_get_perm(blk, &orig_perm, &orig_shared_perm); + + if (ct->perm & ~orig_perm) { + uint64_t new_perm; + Error *local_err =3D NULL; + int ret; + + new_perm =3D orig_perm | ct->perm; + + ret =3D blk_set_perm(blk, new_perm, orig_shared_perm, &local_e= rr); + if (ret < 0) { + error_report_err(local_err); + return 0; + } + } + } + optind =3D 0; return ct->cfunc(blk, argc, argv); } @@ -918,6 +941,7 @@ static const cmdinfo_t write_cmd =3D { .name =3D "write", .altname =3D "w", .cfunc =3D write_f, + .perm =3D BLK_PERM_WRITE, .argmin =3D 2, .argmax =3D -1, .args =3D "[-bcCfquz] [-P pattern] off len", @@ -1093,6 +1117,7 @@ static int writev_f(BlockBackend *blk, int argc, char= **argv); static const cmdinfo_t writev_cmd =3D { .name =3D "writev", .cfunc =3D writev_f, + .perm =3D BLK_PERM_WRITE, .argmin =3D 2, .argmax =3D -1, .args =3D "[-Cfq] [-P pattern] off len [len..]", @@ -1392,6 +1417,7 @@ static int aio_write_f(BlockBackend *blk, int argc, c= har **argv); static const cmdinfo_t aio_write_cmd =3D { .name =3D "aio_write", .cfunc =3D aio_write_f, + .perm =3D BLK_PERM_WRITE, .argmin =3D 2, .argmax =3D -1, .args =3D "[-Cfiquz] [-P pattern] off len [len..]", @@ -1556,6 +1582,7 @@ static const cmdinfo_t truncate_cmd =3D { .name =3D "truncate", .altname =3D "t", .cfunc =3D truncate_f, + .perm =3D BLK_PERM_WRITE | BLK_PERM_RESIZE, .argmin =3D 1, .argmax =3D 1, .args =3D "off", @@ -1653,6 +1680,7 @@ static const cmdinfo_t discard_cmd =3D { .name =3D "discard", .altname =3D "d", .cfunc =3D discard_f, + .perm =3D BLK_PERM_WRITE, .argmin =3D 2, .argmax =3D -1, .args =3D "[-Cq] off len", --=20 1.8.3.1