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Mon, 16 May 2022 14:51:08 +0000 (GMT) Received: from p-imbrenda (unknown [9.145.0.224]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 16 May 2022 14:51:08 +0000 (GMT) Date: Mon, 16 May 2022 16:51:06 +0200 From: Claudio Imbrenda To: Steffen Eiden Cc: Greg KH , Heiko Carstens , Alexander Gordeev , Shuah Khan , Christian Borntraeger , Janosch Frank , David Hildenbrand , Nico Boehr , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH v4 1/2] drivers/s390/char: Add Ultravisor io device Message-ID: <20220516165106.3ef418ce@p-imbrenda> In-Reply-To: <20220516113335.338212-1-seiden@linux.ibm.com> References: <20220510144724.3321985-2-seiden@linux.ibm.com> <20220516113335.338212-1-seiden@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: xBhhIRDv3ikjOUP7QFb53BVkEwra_Cnc X-Proofpoint-ORIG-GUID: trkqZAMsQrxr_CLjR-njliN_lBey1uSB X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.858,Hydra:6.0.486,FMLib:17.11.64.514 definitions=2022-05-16_14,2022-05-16_02,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 malwarescore=0 spamscore=0 clxscore=1015 mlxlogscore=999 bulkscore=0 suspectscore=0 mlxscore=0 lowpriorityscore=0 priorityscore=1501 phishscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2202240000 definitions=main-2205160083 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 16 May 2022 11:33:35 +0000 Steffen Eiden wrote: > This patch adds a new miscdevice to expose some Ultravisor functions > to userspace. Userspace can send IOCTLs to the uvdevice that will then > emit a corresponding Ultravisor Call and hands the result over to > userspace. The uvdevice is available if the Ultravisor Call facility is > present. > Userspace can call the Retrieve Attestation Measurement > Ultravisor Call using IOCTLs on the uvdevice. > > The uvdevice will do some sanity checks first. > Then, copy the request data to kernel space, build the UVCB, > perform the UV call, and copy the result back to userspace. > > Signed-off-by: Steffen Eiden > Reviewed-by: Janosch Frank Reviewed-by: Claudio Imbrenda > --- > After some private discussion "struct uvio_ioctl_cb uv_ioctl" > in "uvio_ioctl()" is now in the stack. > > MAINTAINERS | 2 + > arch/s390/include/asm/uv.h | 23 ++- > arch/s390/include/uapi/asm/uvdevice.h | 51 +++++ > drivers/s390/char/Kconfig | 10 + > drivers/s390/char/Makefile | 1 + > drivers/s390/char/uvdevice.c | 257 ++++++++++++++++++++++++++ > 6 files changed, 343 insertions(+), 1 deletion(-) > create mode 100644 arch/s390/include/uapi/asm/uvdevice.h > create mode 100644 drivers/s390/char/uvdevice.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index e8c52d0192a6..b42ab4a35e18 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -10781,9 +10781,11 @@ F: Documentation/virt/kvm/s390* > F: arch/s390/include/asm/gmap.h > F: arch/s390/include/asm/kvm* > F: arch/s390/include/uapi/asm/kvm* > +F: arch/s390/include/uapi/asm/uvdevice.h > F: arch/s390/kernel/uv.c > F: arch/s390/kvm/ > F: arch/s390/mm/gmap.c > +F: drivers/s390/char/uvdevice.c > F: tools/testing/selftests/kvm/*/s390x/ > F: tools/testing/selftests/kvm/s390x/ > > diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h > index a2d376b8bce3..cfea7b77a5b8 100644 > --- a/arch/s390/include/asm/uv.h > +++ b/arch/s390/include/asm/uv.h > @@ -2,7 +2,7 @@ > /* > * Ultravisor Interfaces > * > - * Copyright IBM Corp. 2019 > + * Copyright IBM Corp. 2019, 2022 > * > * Author(s): > * Vasily Gorbik > @@ -52,6 +52,7 @@ > #define UVC_CMD_UNPIN_PAGE_SHARED 0x0342 > #define UVC_CMD_SET_SHARED_ACCESS 0x1000 > #define UVC_CMD_REMOVE_SHARED_ACCESS 0x1001 > +#define UVC_CMD_RETR_ATTEST 0x1020 > > /* Bits in installed uv calls */ > enum uv_cmds_inst { > @@ -76,6 +77,7 @@ enum uv_cmds_inst { > BIT_UVC_CMD_UNSHARE_ALL = 20, > BIT_UVC_CMD_PIN_PAGE_SHARED = 21, > BIT_UVC_CMD_UNPIN_PAGE_SHARED = 22, > + BIT_UVC_CMD_RETR_ATTEST = 28, > }; > > enum uv_feat_ind { > @@ -219,6 +221,25 @@ struct uv_cb_share { > u64 reserved28; > } __packed __aligned(8); > > +/* Retrieve Attestation Measurement */ > +struct uv_cb_attest { > + struct uv_cb_header header; /* 0x0000 */ > + u64 reserved08[2]; /* 0x0008 */ > + u64 arcb_addr; /* 0x0018 */ > + u64 cont_token; /* 0x0020 */ > + u8 reserved28[6]; /* 0x0028 */ > + u16 user_data_len; /* 0x002e */ > + u8 user_data[256]; /* 0x0030 */ > + u32 reserved130[3]; /* 0x0130 */ > + u32 meas_len; /* 0x013c */ > + u64 meas_addr; /* 0x0140 */ > + u8 config_uid[16]; /* 0x0148 */ > + u32 reserved158; /* 0x0158 */ > + u32 add_data_len; /* 0x015c */ > + u64 add_data_addr; /* 0x0160 */ > + u64 reserved168[4]; /* 0x0168 */ > +} __packed __aligned(8); > + > static inline int __uv_call(unsigned long r1, unsigned long r2) > { > int cc; > diff --git a/arch/s390/include/uapi/asm/uvdevice.h b/arch/s390/include/uapi/asm/uvdevice.h > new file mode 100644 > index 000000000000..d0bdde4969a1 > --- /dev/null > +++ b/arch/s390/include/uapi/asm/uvdevice.h > @@ -0,0 +1,51 @@ > +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ > +/* > + * Copyright IBM Corp. 2022 > + * Author(s): Steffen Eiden > + */ > +#ifndef __S390_ASM_UVDEVICE_H > +#define __S390_ASM_UVDEVICE_H > + > +#include > + > +struct uvio_ioctl_cb { > + __u32 flags; > + __u16 uv_rc; /* UV header rc value */ > + __u16 uv_rrc; /* UV header rrc value */ > + __u64 argument_addr; /* Userspace address of uvio argument */ > + __u32 argument_len; > + __u8 reserved14[0x40 - 0x14]; /* must be zero */ > +}; > + > +#define UVIO_ATT_USER_DATA_LEN 0x100 > +#define UVIO_ATT_UID_LEN 0x10 > +struct uvio_attest { > + __u64 arcb_addr; /* 0x0000 */ > + __u64 meas_addr; /* 0x0008 */ > + __u64 add_data_addr; /* 0x0010 */ > + __u8 user_data[UVIO_ATT_USER_DATA_LEN]; /* 0x0018 */ > + __u8 config_uid[UVIO_ATT_UID_LEN]; /* 0x0118 */ > + __u32 arcb_len; /* 0x0128 */ > + __u32 meas_len; /* 0x012c */ > + __u32 add_data_len; /* 0x0130 */ > + __u16 user_data_len; /* 0x0134 */ > + __u16 reserved136; /* 0x0136 */ > +}; > + > +/* > + * The following max values define an upper length for the IOCTL in/out buffers. > + * However, they do not represent the maximum the Ultravisor allows which is > + * often way smaller. By allowing larger buffer sizes we hopefully do not need > + * to update the code with every machine update. It is therefore possible for > + * userspace to request more memory than actually used by kernel/UV. > + */ > +#define UVIO_ATT_ARCB_MAX_LEN 0x100000 > +#define UVIO_ATT_MEASUREMENT_MAX_LEN 0x8000 > +#define UVIO_ATT_ADDITIONAL_MAX_LEN 0x8000 > + > +#define UVIO_DEVICE_NAME "uv" > +#define UVIO_TYPE_UVC 'u' > + > +#define UVIO_IOCTL_ATT _IOWR(UVIO_TYPE_UVC, 0x01, struct uvio_ioctl_cb) > + > +#endif /* __S390_ASM_UVDEVICE_H */ > diff --git a/drivers/s390/char/Kconfig b/drivers/s390/char/Kconfig > index 6cc4b19acf85..e9b9902abbaf 100644 > --- a/drivers/s390/char/Kconfig > +++ b/drivers/s390/char/Kconfig > @@ -100,6 +100,16 @@ config SCLP_OFB > This option enables the Open-for-Business interface to the s390 > Service Element. > > +config S390_UV_UAPI > + def_tristate y > + prompt "Ultravisor userspace API" > + help > + Selecting exposes parts of the UV interface to userspace > + by providing a misc character device at /dev/uv. > + Using IOCTLs one can interact with the UV. > + The device is only available if the Ultravisor > + Facility (158) is present. > + > config S390_TAPE > def_tristate m > prompt "S/390 tape device support" > diff --git a/drivers/s390/char/Makefile b/drivers/s390/char/Makefile > index c6fdb81a068a..ce32270082f5 100644 > --- a/drivers/s390/char/Makefile > +++ b/drivers/s390/char/Makefile > @@ -48,6 +48,7 @@ obj-$(CONFIG_MONREADER) += monreader.o > obj-$(CONFIG_MONWRITER) += monwriter.o > obj-$(CONFIG_S390_VMUR) += vmur.o > obj-$(CONFIG_CRASH_DUMP) += sclp_sdias.o zcore.o > +obj-$(CONFIG_S390_UV_UAPI) += uvdevice.o > > hmcdrv-objs := hmcdrv_mod.o hmcdrv_dev.o hmcdrv_ftp.o hmcdrv_cache.o diag_ftp.o sclp_ftp.o > obj-$(CONFIG_HMC_DRV) += hmcdrv.o > diff --git a/drivers/s390/char/uvdevice.c b/drivers/s390/char/uvdevice.c > new file mode 100644 > index 000000000000..e8e1409df015 > --- /dev/null > +++ b/drivers/s390/char/uvdevice.c > @@ -0,0 +1,257 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright IBM Corp. 2022 > + * Author(s): Steffen Eiden > + * > + * This file provides a Linux misc device to give userspace access to some > + * Ultravisor (UV) functions. The device only accepts IOCTLs and will only > + * be present if the Ultravisor facility (158) is present. > + * > + * When userspace sends a valid IOCTL uvdevice will copy the input data to > + * kernel space, do some basic validity checks to avoid kernel/system > + * corruption. Any other check that the Ultravisor does will not be done by > + * the uvdevice to keep changes minimal when adding new functionalities > + * to existing UV-calls. > + * After the checks uvdevice builds a corresponding > + * Ultravisor Call Control Block, and sends the request to the Ultravisor. > + * Then, it copies the response, including the return codes, back to userspace. > + * It is the responsibility of the userspace to check for any error issued > + * by UV and to interpret the UV response. The uvdevice acts as a communication > + * channel for userspace to the Ultravisor. > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#include > +#include > + > +static int uvio_build_uvcb_attest(struct uv_cb_attest *uvcb_attest, u8 *arcb, > + u8 *meas, u8 *add_data, struct uvio_attest *uvio_attest) > +{ > + void __user *user_buf_arcb = (void __user *)uvio_attest->arcb_addr; > + > + if (copy_from_user(arcb, user_buf_arcb, uvio_attest->arcb_len)) > + return -EFAULT; > + > + uvcb_attest->header.len = sizeof(*uvcb_attest); > + uvcb_attest->header.cmd = UVC_CMD_RETR_ATTEST; > + uvcb_attest->arcb_addr = (u64)arcb; > + uvcb_attest->cont_token = 0; > + uvcb_attest->user_data_len = uvio_attest->user_data_len; > + memcpy(uvcb_attest->user_data, uvio_attest->user_data, sizeof(uvcb_attest->user_data)); > + uvcb_attest->meas_len = uvio_attest->meas_len; > + uvcb_attest->meas_addr = (u64)meas; > + uvcb_attest->add_data_len = uvio_attest->add_data_len; > + uvcb_attest->add_data_addr = (u64)add_data; > + > + return 0; > +} > + > +static int uvio_copy_attest_result_to_user(struct uv_cb_attest *uvcb_attest, > + struct uvio_ioctl_cb *uv_ioctl, > + u8 *measurement, u8 *add_data, > + struct uvio_attest *uvio_attest) > +{ > + struct uvio_attest __user *user_uvio_attest = (void __user *)uv_ioctl->argument_addr; > + void __user *user_buf_add = (void __user *)uvio_attest->add_data_addr; > + void __user *user_buf_meas = (void __user *)uvio_attest->meas_addr; > + void __user *user_buf_uid = &user_uvio_attest->config_uid; > + > + if (copy_to_user(user_buf_meas, measurement, uvio_attest->meas_len)) > + return -EFAULT; > + if (add_data && copy_to_user(user_buf_add, add_data, uvio_attest->add_data_len)) > + return -EFAULT; > + if (copy_to_user(user_buf_uid, uvcb_attest->config_uid, sizeof(uvcb_attest->config_uid))) > + return -EFAULT; > + return 0; > +} > + > +static int get_uvio_attest(struct uvio_ioctl_cb *uv_ioctl, struct uvio_attest *uvio_attest) > +{ > + u8 __user *user_arg_buf = (u8 __user *)uv_ioctl->argument_addr; > + > + if (copy_from_user(uvio_attest, user_arg_buf, sizeof(*uvio_attest))) > + return -EFAULT; > + > + if (uvio_attest->arcb_len > UVIO_ATT_ARCB_MAX_LEN) > + return -EINVAL; > + if (uvio_attest->arcb_len == 0) > + return -EINVAL; > + if (uvio_attest->meas_len > UVIO_ATT_MEASUREMENT_MAX_LEN) > + return -EINVAL; > + if (uvio_attest->meas_len == 0) > + return -EINVAL; > + if (uvio_attest->add_data_len > UVIO_ATT_ADDITIONAL_MAX_LEN) > + return -EINVAL; > + if (uvio_attest->reserved136) > + return -EINVAL; > + return 0; > +} > + > +/** > + * uvio_attestation() - Perform a Retrieve Attestation Measurement UVC. > + * > + * @uv_ioctl: ioctl control block > + * > + * uvio_attestation() does a Retrieve Attestation Measurement Ultravisor Call. > + * It verifies that the given userspace addresses are valid and request sizes > + * are sane. Every other check is made by the Ultravisor (UV) and won't result > + * in a negative return value. It copies the input to kernelspace, builds the > + * request, sends the UV-call, and copies the result to userspace. > + * > + * The Attestation Request has two input and two outputs. > + * ARCB and User Data are inputs for the UV generated by userspace. > + * Measurement and Additional Data are outputs for userspace generated by UV. > + * > + * The Attestation Request Control Block (ARCB) is a cryptographically verified > + * and secured request to UV and User Data is some plaintext data which is > + * going to be included in the Attestation Measurement calculation. > + * > + * Measurement is a cryptographic measurement of the callers properties, > + * optional data configured by the ARCB and the user data. If specified by the > + * ARCB, UV will add some Additional Data to the measurement calculation. > + * This Additional Data is then returned as well. > + * > + * If the Retrieve Attestation Measurement UV facility is not present, > + * UV will return invalid command rc. This won't be fenced in the driver > + * and does not result in a negative return value. > + * > + * Context: might sleep > + * > + * Return: 0 on success or a negative error code on error. > + */ > +static int uvio_attestation(struct uvio_ioctl_cb *uv_ioctl) > +{ > + struct uv_cb_attest *uvcb_attest = NULL; > + struct uvio_attest *uvio_attest = NULL; > + u8 *measurement = NULL; > + u8 *add_data = NULL; > + u8 *arcb = NULL; > + int ret; > + > + ret = -EINVAL; > + if (uv_ioctl->argument_len != sizeof(*uvio_attest)) > + goto out; > + > + ret = -ENOMEM; > + uvio_attest = kzalloc(sizeof(*uvio_attest), GFP_KERNEL); > + if (!uvio_attest) > + goto out; > + > + ret = get_uvio_attest(uv_ioctl, uvio_attest); > + if (ret) > + goto out; > + > + ret = -ENOMEM; > + arcb = kvzalloc(uvio_attest->arcb_len, GFP_KERNEL); > + measurement = kvzalloc(uvio_attest->meas_len, GFP_KERNEL); > + if (!arcb || !measurement) > + goto out; > + > + if (uvio_attest->add_data_len) { > + add_data = kvzalloc(uvio_attest->add_data_len, GFP_KERNEL); > + if (!add_data) > + goto out; > + } > + > + uvcb_attest = kzalloc(sizeof(*uvcb_attest), GFP_KERNEL); > + if (!uvcb_attest) > + goto out; > + > + ret = uvio_build_uvcb_attest(uvcb_attest, arcb, measurement, add_data, uvio_attest); > + if (ret) > + goto out; > + > + uv_call_sched(0, (u64)uvcb_attest); > + > + uv_ioctl->uv_rc = uvcb_attest->header.rc; > + uv_ioctl->uv_rrc = uvcb_attest->header.rrc; > + > + ret = uvio_copy_attest_result_to_user(uvcb_attest, uv_ioctl, measurement, add_data, > + uvio_attest); > +out: > + kvfree(arcb); > + kvfree(measurement); > + kvfree(add_data); > + kfree(uvio_attest); > + kfree(uvcb_attest); > + return ret; > +} > + > +static int uvio_copy_and_check_ioctl(struct uvio_ioctl_cb *ioctl, void __user *argp) > +{ > + if (copy_from_user(ioctl, argp, sizeof(*ioctl))) > + return -EFAULT; > + if (ioctl->flags != 0) > + return -EINVAL; > + if (memchr_inv(ioctl->reserved14, 0, sizeof(ioctl->reserved14))) > + return -EINVAL; > + > + return 0; > +} > + > +/* > + * IOCTL entry point for the Ultravisor device. > + */ > +static long uvio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > +{ > + void __user *argp = (void __user *)arg; > + struct uvio_ioctl_cb uv_ioctl = { }; > + long ret; > + > + switch (cmd) { > + case UVIO_IOCTL_ATT: > + ret = uvio_copy_and_check_ioctl(&uv_ioctl, argp); > + if (ret) > + return ret; > + ret = uvio_attestation(&uv_ioctl); > + break; > + default: > + ret = -ENOIOCTLCMD; > + break; > + } > + if (ret) > + return ret; > + > + if (copy_to_user(argp, &uv_ioctl, sizeof(uv_ioctl))) > + ret = -EFAULT; > + > + return ret; > +} > + > +static const struct file_operations uvio_dev_fops = { > + .owner = THIS_MODULE, > + .unlocked_ioctl = uvio_ioctl, > + .llseek = no_llseek, > +}; > + > +static struct miscdevice uvio_dev_miscdev = { > + .minor = MISC_DYNAMIC_MINOR, > + .name = UVIO_DEVICE_NAME, > + .fops = &uvio_dev_fops, > +}; > + > +static void __exit uvio_dev_exit(void) > +{ > + misc_deregister(&uvio_dev_miscdev); > +} > + > +static int __init uvio_dev_init(void) > +{ > + if (!test_facility(158)) > + return -ENXIO; > + return misc_register(&uvio_dev_miscdev); > +} > + > +module_init(uvio_dev_init); > +module_exit(uvio_dev_exit); > + > +MODULE_AUTHOR("IBM Corporation"); > +MODULE_LICENSE("GPL"); > +MODULE_DESCRIPTION("Ultravisor UAPI driver");