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a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:date:from:in-reply-to:message-id :mime-version:references:subject:to; s=pp1; bh=GN1Hq6j9I3FWk+035 MqB8fKDHbeRygIDEpGYhCCG8Qk=; b=hxMl2x/zNMiUxufL6zIrq7ct0X+Dz2FII hoqHw35SFlDQea9x3uyfZOKR2Y0SOjJy3QJQ4FobMNW/m3toL7i6zIyyDNgI29wF W0D0Be2BCZX8Wc5Cfb8XgAcReAA/zj3odEi3K2vkjPnq5GooWcYqKnkisinGP1JY AERQZpYkb6VYMDE/hx0dsH47cfCZLNl7P1MraFFJ9qLZC51eFrWsyI7k8b0q5FKO r+dXrbXsVpCp1jpHdd4NFhopUn/t0mIVE5q6423sZmbXewTkgakZkELiRLUtWytK hmdB3rnNxq/w2vOhCtkIdxYN2MjF9ttEjuZkC4XvR49ZQy747BPZQ== From: Stefan Berger To: qemu-devel@nongnu.org Cc: berrange@redhat.com, marcandre.lureau@gmail.com, Stefan Berger Subject: [PATCH v2 2/2] tpm_emulator: Read control channel response in 2 passes Date: Wed, 16 Oct 2024 09:34:50 -0400 Message-ID: <20241016133450.1071197-3-stefanb@linux.ibm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241016133450.1071197-1-stefanb@linux.ibm.com> References: <20241016133450.1071197-1-stefanb@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: p_X998_q_CjIygA8mHS2Q0yc9jHLk-2b X-Proofpoint-GUID: W-sZN8HUY6Ht_cT4it85qZOcjiYe1OyK Content-Transfer-Encoding: quoted-printable X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1051,Hydra:6.0.680,FMLib:17.12.62.30 definitions=2024-10-15_01,2024-10-11_01,2024-09-30_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 mlxlogscore=754 clxscore=1015 lowpriorityscore=0 impostorscore=0 mlxscore=0 adultscore=0 priorityscore=1501 suspectscore=0 malwarescore=0 bulkscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2409260000 definitions=main-2410160084 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=148.163.158.5; envelope-from=stefanb@linux.ibm.com; helo=mx0b-001b2d01.pphosted.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, 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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @ibm.com) X-ZM-MESSAGEID: 1729085755465116600 Content-Type: text/plain; charset="utf-8" Error responses from swtpm are always only 4 bytes long with the exception of CMD_GET_STATEBLOB that returns more bytes. Therefore, read the entire response in 2 passes and stop if the first 4 bytes indicate an error response with no subsequent bytes readable. Read the rest in a 2nd pass, if needed. This avoids getting stuck while waiting for too many bytes if only 4 bytes were sent due to an error message. The 'getting stuck' condition has not been observed in practice so far, though. Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2615 Signed-off-by: Stefan Berger --- backends/tpm/tpm_emulator.c | 31 +++++++++++++++++++++++++++++-- 1 file changed, 29 insertions(+), 2 deletions(-) diff --git a/backends/tpm/tpm_emulator.c b/backends/tpm/tpm_emulator.c index b0e2fb3fc7..8f5d31be09 100644 --- a/backends/tpm/tpm_emulator.c +++ b/backends/tpm/tpm_emulator.c @@ -129,6 +129,9 @@ static int tpm_emulator_ctrlcmd(TPMEmulator *tpm, unsig= ned long cmd, void *msg, uint32_t cmd_no =3D cpu_to_be32(cmd); ssize_t n =3D sizeof(uint32_t) + msg_len_in; uint8_t *buf =3D NULL; + ptm_res res; + off_t o =3D 0; + int to_read; =20 WITH_QEMU_LOCK_GUARD(&tpm->mutex) { buf =3D g_alloca(n); @@ -140,11 +143,35 @@ static int tpm_emulator_ctrlcmd(TPMEmulator *tpm, uns= igned long cmd, void *msg, return -1; } =20 - if (msg_len_out !=3D 0) { - n =3D qemu_chr_fe_read_all(dev, msg, msg_len_out); + /* + * Any response will be at least 4 bytes long. Error responses are= only + * 4 bytes (=3Dsizeof(ptm_res)), with exception by CMD_GET_STATEBL= OB. + * Therefore, read response in 2 passes, returning when an error + * response is encountered. + */ + if (cmd =3D=3D CMD_GET_STATEBLOB) { + to_read =3D msg_len_out; + } else { + to_read =3D sizeof(res); + } + + while (msg_len_out > 0) { + n =3D qemu_chr_fe_read_all(dev, (uint8_t *)msg + o, to_read); if (n <=3D 0) { return -1; } + msg_len_out -=3D to_read; + if (msg_len_out =3D=3D 0) { + return 0; + } + + memcpy(&res, msg, sizeof(res)); + if (res) { + return 0; + } + + o =3D to_read; + to_read =3D msg_len_out; } } =20 --=20 2.47.0