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bh=WNBvx4THG0M9pR8FSX6Ps6fHmdrKHB/so8DozTyNlvw=; b=KPrcLxfkqsJlO7o5wyzQEX+9Exg87IpoYGHF3eArwNNOGuz3F5oL2OOo8KH1Qw6A/dclMe X9MS5uUHKCOY6DerufzYZ/6CwVFCoSbkzibWraLnQZ6O5+NmxcyZci/9c+7NAlG/rc1mUu Trg3DRmRQLjx/FPwSuFIzKpBKk4mb24= X-MC-Unique: NLdMEcwnOCunYQJuxnjR3Q-1 From: Kevin Wolf To: qemu-block@nongnu.org Subject: [PATCH for-5.1 2/3] file-posix: Fix check_hdev_writable() with auto-read-only Date: Fri, 17 Jul 2020 12:54:25 +0200 Message-Id: <20200717105426.51134-3-kwolf@redhat.com> In-Reply-To: <20200717105426.51134-1-kwolf@redhat.com> References: <20200717105426.51134-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=207.211.31.81; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/17 05:27:47 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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, mreitz@redhat.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" For Linux block devices, being able to open the device read-write doesn't necessarily mean that the device is actually writable (one example is a read-only LV, as you get with lvchange -pr ). We have check_hdev_writable() to check this condition and fail opening the image read-write if it's not actually writable. However, this check doesn't take auto-read-only into account, but results in a hard failure instead of downgrading to read-only where possible. Fix this and do the writable check not based on BDRV_O_RDWR, but only when this actually results in opening the file read-write. A second check is inserted in raw_reconfigure_getfd() to have the same check when dynamic auto-read-only upgrades an image file from read-only to read-write. Signed-off-by: Kevin Wolf Reviewed-by: Max Reitz --- block/file-posix.c | 33 +++++++++++++++++++++------------ 1 file changed, 21 insertions(+), 12 deletions(-) diff --git a/block/file-posix.c b/block/file-posix.c index e35e15185a..659f780570 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -401,7 +401,7 @@ static void raw_probe_alignment(BlockDriverState *bs, i= nt fd, Error **errp) } } =20 -static int check_hdev_writable(BDRVRawState *s) +static int check_hdev_writable(int fd) { #if defined(BLKROGET) /* Linux block devices can be configured "read-only" using blockdev(8). @@ -415,7 +415,7 @@ static int check_hdev_writable(BDRVRawState *s) struct stat st; int readonly =3D 0; =20 - if (fstat(s->fd, &st)) { + if (fstat(fd, &st)) { return -errno; } =20 @@ -423,7 +423,7 @@ static int check_hdev_writable(BDRVRawState *s) return 0; } =20 - if (ioctl(s->fd, BLKROGET, &readonly) < 0) { + if (ioctl(fd, BLKROGET, &readonly) < 0) { return -errno; } =20 @@ -618,6 +618,15 @@ static int raw_open_common(BlockDriverState *bs, QDict= *options, } s->fd =3D fd; =20 + /* Check s->open_flags rather than bdrv_flags due to auto-read-only */ + if (s->open_flags & O_RDWR) { + ret =3D check_hdev_writable(s->fd); + if (ret < 0) { + error_setg_errno(errp, -ret, "The device is not writable"); + goto fail; + } + } + s->perm =3D 0; s->shared_perm =3D BLK_PERM_ALL; =20 @@ -1010,6 +1019,15 @@ static int raw_reconfigure_getfd(BlockDriverState *b= s, int flags, } } =20 + if (fd !=3D -1 && (*open_flags & O_RDWR)) { + ret =3D check_hdev_writable(fd); + if (ret < 0) { + qemu_close(fd); + error_setg_errno(errp, -ret, "The device is not writable"); + return -1; + } + } + return fd; } =20 @@ -3454,15 +3472,6 @@ hdev_open_Mac_error: /* Since this does ioctl the device must be already opened */ bs->sg =3D hdev_is_sg(bs); =20 - if (flags & BDRV_O_RDWR) { - ret =3D check_hdev_writable(s); - if (ret < 0) { - raw_close(bs); - error_setg_errno(errp, -ret, "The device is not writable"); - return ret; - } - } - return ret; } =20 --=20 2.25.4