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Shutemov" , Dave Hansen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" Cc: linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev, Dionna Amalie Glaze , James Bottomley , Dan Middleton , Mikko Ylinen , Sathyanarayanan Kuppuswamy X-Mailer: b4 0.13.0 Add new TSM APIs for TVM guest drivers to register and expose measurement registers (MRs) as sysfs attributes (files). New TSM APIs: - `tsm_register_measurement(struct tsm_measurement *)`: Register a set of MRs with the TSM core. - `tsm_unregister_measurement(struct tsm_measurement *)`: Unregister a previously registered set of MRs. These APIs are centered around `struct tsm_measurement`, which includes an array of `struct tsm_measurement_register`s with properties (`tsm_measurement_register::mr_flags`) like *Readable* (`TSM_MR_F_R`) and *Extensible* (`TSM_MR_F_X`). For details, see include/linux/tsm.h. Upon successful registration, the TSM core exposes MRs in sysfs at /sys/kernel/tsm/MR_PROVIDER/, where MR_PROVIDER is the measurement provider's name (`tsm_measurement::name`). Each MR is accessible either as a file (/sys/kernel/tsm/MR_PROVIDER/MR_NAME contains the MR value) or a directory (/sys/kernel/tsm/MR_PROVIDER/MR_NAME/HASH/digest contains the MR value) depending on whether `TSM_MR_F_F` is set or cleared (in `tsm_measurement_register::mr_flags`). MR_NAME is the name (`tsm_measurement_register::mr_name`) of the MR, while HASH is the hash algorithm (`tsm_measurement_register::mr_hash`) name in the latter case. *Crypto Agility* is supported by merging independent MRs with a common name into a single directory, each represented by its HASH/digest file. Note that HASH must be distinct or behavior is undefined. Signed-off-by: Cedric Xing --- Documentation/ABI/testing/sysfs-kernel-tsm | 20 ++ MAINTAINERS | 2 +- drivers/virt/coco/Kconfig | 17 +- drivers/virt/coco/Makefile | 2 + drivers/virt/coco/{tsm.c => tsm-core.c} | 6 +- drivers/virt/coco/tsm-mr.c | 383 +++++++++++++++++++++++++++++ include/linux/tsm.h | 65 +++++ 7 files changed, 492 insertions(+), 3 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-kernel-tsm b/Documentation/ABI/testing/sysfs-kernel-tsm new file mode 100644 index 000000000000..99735cf4da5c --- /dev/null +++ b/Documentation/ABI/testing/sysfs-kernel-tsm @@ -0,0 +1,20 @@ +What: /sys/kernel/tsm// +Date: February 2025 +Contact: Cedric Xing . +Description: + This file contains the value of the measurement register + . Depending on the CC architecture, this file may be + writable, in which case the value written will be the new value + of . Each write must start at the beginning and be of + the same size as the file. Partial writes are not permitted. + +What: /sys/kernel/tsm////digest +Date: February 2025 +Contact: Cedric Xing . +Description: + This file contains the value of the measurement register + . Depending on the CC architecture, this file may be + writable, in which case any value written may be extended to + using . Each write must start at the beginning + and be of the same size as the file. Partial writes are not + permitted. diff --git a/MAINTAINERS b/MAINTAINERS index 4ff26fa94895..a5eef4c7234c 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -24104,7 +24104,7 @@ M: Dan Williams L: linux-coco@lists.linux.dev S: Maintained F: Documentation/ABI/testing/configfs-tsm -F: drivers/virt/coco/tsm.c +F: drivers/virt/coco/tsm*.c F: include/linux/tsm.h TRUSTED SERVICES TEE DRIVER diff --git a/drivers/virt/coco/Kconfig b/drivers/virt/coco/Kconfig index ff869d883d95..3fa38fd731b9 100644 --- a/drivers/virt/coco/Kconfig +++ b/drivers/virt/coco/Kconfig @@ -5,7 +5,22 @@ config TSM_REPORTS select CONFIGFS_FS - tristate + select CRYPTO_HASH_INFO + select CRYPTO + tristate "Trusted Security Module (TSM) support" + +if TSM_REPORTS + +config TSM_MR_MAXBANKS + int "Max number of banks of Measurement Registers" + range 1 8 + default 1 + help + A "bank" is a group of MRs that use the same hash algorithm. This + option specifies the maximal number of banks each Measurement + Register (MR) can support. + +endif source "drivers/virt/coco/efi_secret/Kconfig" diff --git a/drivers/virt/coco/Makefile b/drivers/virt/coco/Makefile index c3d07cfc087e..4b108d8df1bd 100644 --- a/drivers/virt/coco/Makefile +++ b/drivers/virt/coco/Makefile @@ -2,6 +2,8 @@ # # Confidential computing related collateral # +tsm-y += tsm-core.o tsm-mr.o + obj-$(CONFIG_TSM_REPORTS) += tsm.o obj-$(CONFIG_EFI_SECRET) += efi_secret/ obj-$(CONFIG_ARM_PKVM_GUEST) += pkvm-guest/ diff --git a/drivers/virt/coco/tsm.c b/drivers/virt/coco/tsm-core.c similarity index 99% rename from drivers/virt/coco/tsm.c rename to drivers/virt/coco/tsm-core.c index 9432d4e303f1..ab5269db9c13 100644 --- a/drivers/virt/coco/tsm.c +++ b/drivers/virt/coco/tsm-core.c @@ -476,6 +476,9 @@ int tsm_unregister(const struct tsm_ops *ops) } EXPORT_SYMBOL_GPL(tsm_unregister); +int tsm_mr_init(void); +void tsm_mr_exit(void); + static struct config_group *tsm_report_group; static int __init tsm_init(void) @@ -497,12 +500,13 @@ static int __init tsm_init(void) } tsm_report_group = tsm; - return 0; + return tsm_mr_init(); } module_init(tsm_init); static void __exit tsm_exit(void) { + tsm_mr_exit(); configfs_unregister_default_group(tsm_report_group); configfs_unregister_subsystem(&tsm_configfs); } diff --git a/drivers/virt/coco/tsm-mr.c b/drivers/virt/coco/tsm-mr.c new file mode 100644 index 000000000000..8a96b2a78869 --- /dev/null +++ b/drivers/virt/coco/tsm-mr.c @@ -0,0 +1,383 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright(c) 2024-2025 Intel Corporation. All rights reserved. */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include + +int tsm_mr_init(void); +void tsm_mr_exit(void); + +enum tmr_dir_battr_index { + TMR_DIR_BA_DIGEST, + TMR_DIR_BA__COUNT, +}; + +struct tmr_dir { + struct kobject kobj; + struct bin_attribute battrs[CONFIG_TSM_MR_MAXBANKS][TMR_DIR_BA__COUNT]; + int algo; +}; + +struct tmr_provider { + struct kset kset; + struct rw_semaphore rwsem; + struct bin_attribute *mrfiles; + struct tsm_measurement *tmr; + bool in_sync; +}; + +static inline struct tmr_provider *tmr_mr_to_provider(const struct tsm_measurement_register *mr, + struct kobject *kobj) +{ + if (mr->mr_flags & TSM_MR_F_F) + return container_of(kobj, struct tmr_provider, kset.kobj); + else + return container_of(kobj->kset, struct tmr_provider, kset); +} + +static inline int tmr_call_refresh(struct tmr_provider *pvd, + const struct tsm_measurement_register *mr) +{ + int rc; + + rc = pvd->tmr->refresh(pvd->tmr, mr); + if (rc) + pr_warn("%s.refresh(%s) failed %d\n", kobject_name(&pvd->kset.kobj), mr->mr_name, + rc); + return rc; +} + +static inline int tmr_call_extend(struct tmr_provider *pvd, + const struct tsm_measurement_register *mr, const u8 *data) +{ + int rc; + + rc = pvd->tmr->extend(pvd->tmr, mr, data); + if (rc) + pr_warn("%s.extend(%s) failed %d\n", kobject_name(&pvd->kset.kobj), mr->mr_name, + rc); + return rc; +} + +static ssize_t tmr_digest_read(struct file *filp, struct kobject *kobj, struct bin_attribute *attr, + char *buffer, loff_t off, size_t count) +{ + const struct tsm_measurement_register *mr; + struct tmr_provider *pvd; + int rc; + + if (off < 0 || off > attr->size) + return -EINVAL; + + count = min(count, attr->size - (size_t)off); + if (!count) + return count; + + mr = attr->private; + pvd = tmr_mr_to_provider(mr, kobj); + rc = down_read_interruptible(&pvd->rwsem); + if (rc) + return rc; + + /* + * pvd->in_sync indicates if any MRs have been written/extended since the last + * pvd->refresh() call. When pvd->in_sync is false, pvd->refresh() is necessary to sync the + * cached values of all live (L) MRs with the underlying hardware. + */ + if ((mr->mr_flags & TSM_MR_F_L) && !pvd->in_sync) { + up_read(&pvd->rwsem); + + rc = down_write_killable(&pvd->rwsem); + if (rc) + return rc; + + if (!pvd->in_sync) { + rc = tmr_call_refresh(pvd, mr); + pvd->in_sync = !rc; + } + + downgrade_write(&pvd->rwsem); + } + + if (!rc) + memcpy(buffer, mr->mr_value + off, count); + + up_read(&pvd->rwsem); + return rc ?: count; +} + +static ssize_t tmr_digest_write(struct file *filp, struct kobject *kobj, struct bin_attribute *attr, + char *buffer, loff_t off, size_t count) +{ + const struct tsm_measurement_register *mr; + struct tmr_provider *pvd; + ssize_t rc; + + if (off != 0 || count != attr->size) + return -EINVAL; + + mr = attr->private; + pvd = tmr_mr_to_provider(mr, kobj); + rc = down_write_killable(&pvd->rwsem); + if (rc) + return rc; + + if (mr->mr_flags & TSM_MR_F_X) + rc = tmr_call_extend(pvd, mr, buffer); + else + memcpy(mr->mr_value, buffer, count); + + // clear pvd->in_sync so the next read from any live (L) MR will trigger pvd->refresh() + if (!rc) + pvd->in_sync = false; + + up_write(&pvd->rwsem); + return rc ?: count; +} + +static void tmr_dir_release(struct kobject *kobj) +{ + struct tmr_dir *mrd; + + mrd = container_of(kobj, typeof(*mrd), kobj); + kfree(mrd); +} + +static const struct kobj_type tmr_dir_ktype = { + .release = tmr_dir_release, + .sysfs_ops = &kobj_sysfs_ops, +}; + +static struct tmr_dir *tmr_dir_create(const struct tsm_measurement_register *mr, + struct tmr_provider *pvd) +{ + struct kobject *kobj; + struct tmr_dir *mrd; + + kobj = kset_find_obj(&pvd->kset, mr->mr_name); + if (kobj) { + mrd = container_of(kobj, typeof(*mrd), kobj); + kobject_put(kobj); + if (++mrd->algo >= CONFIG_TSM_MR_MAXBANKS) { + --mrd->algo; + return ERR_PTR(-ENOSPC); + } + } else { + int rc; + + mrd = kzalloc(sizeof(*mrd), GFP_KERNEL); + if (!mrd) + return ERR_PTR(-ENOMEM); + + mrd->kobj.kset = &pvd->kset; + rc = kobject_init_and_add(&mrd->kobj, &tmr_dir_ktype, NULL, "%s", mr->mr_name); + if (rc) { + kfree(mrd); + return ERR_PTR(rc); + } + } + + sysfs_bin_attr_init(&mrd->battrs[mrd->algo][TMR_DIR_BA_DIGEST]); + mrd->battrs[mrd->algo][TMR_DIR_BA_DIGEST].attr.name = "digest"; + if (mr->mr_flags & TSM_MR_F_W) + mrd->battrs[mrd->algo][TMR_DIR_BA_DIGEST].attr.mode |= S_IWUSR | S_IWGRP; + if (mr->mr_flags & TSM_MR_F_R) + mrd->battrs[mrd->algo][TMR_DIR_BA_DIGEST].attr.mode |= S_IRUGO; + + mrd->battrs[mrd->algo][TMR_DIR_BA_DIGEST].size = mr->mr_size; + mrd->battrs[mrd->algo][TMR_DIR_BA_DIGEST].read = tmr_digest_read; + mrd->battrs[mrd->algo][TMR_DIR_BA_DIGEST].write = tmr_digest_write; + mrd->battrs[mrd->algo][TMR_DIR_BA_DIGEST].private = (void *)mr; + + return mrd; +} + +static void tmr_provider_release(struct kobject *kobj) +{ + struct tmr_provider *pvd; + + pvd = container_of(kobj, typeof(*pvd), kset.kobj); + if (!WARN_ON(!list_empty(&pvd->kset.list))) { + kfree(pvd->mrfiles); + kfree(pvd); + } +} + +static const struct kobj_type _mr_provider_ktype = { + .release = tmr_provider_release, + .sysfs_ops = &kobj_sysfs_ops, +}; + +static struct kset *tmr_sysfs_root; + +static struct tmr_provider *tmr_provider_create(struct tsm_measurement *tmr) +{ + struct tmr_provider *pvd __free(kfree); + int rc; + + pvd = kzalloc(sizeof(*pvd), GFP_KERNEL); + if (!pvd) + return ERR_PTR(-ENOMEM); + + if (!tmr->name || !tmr->mrs || !tmr->refresh || !tmr->extend) + return ERR_PTR(-EINVAL); + + rc = kobject_set_name(&pvd->kset.kobj, "%s", tmr->name); + if (rc) + return ERR_PTR(rc); + + pvd->kset.kobj.kset = tmr_sysfs_root; + pvd->kset.kobj.ktype = &_mr_provider_ktype; + pvd->tmr = tmr; + + init_rwsem(&pvd->rwsem); + + rc = kset_register(&pvd->kset); + if (rc) + return ERR_PTR(rc); + + return_ptr(pvd); +} + +DEFINE_FREE(_unregister_measurement, struct tmr_provider *, + if (!IS_ERR_OR_NULL(_T)) tsm_unregister_measurement(_T->tmr)); + +int tsm_register_measurement(struct tsm_measurement *tmr) +{ + struct tmr_provider *pvd __free(_unregister_measurement); + int rc, nr; + + pvd = tmr_provider_create(tmr); + if (IS_ERR(pvd)) + return PTR_ERR(pvd); + + nr = 0; + for (int i = 0; tmr->mrs[i].mr_name; ++i) { + // flat files are counted and skipped + if (tmr->mrs[i].mr_flags & TSM_MR_F_F) { + ++nr; + continue; + } + + struct tmr_dir *mrd; + struct bin_attribute *battrs[TMR_DIR_BA__COUNT + 1] = {}; + struct attribute_group agrp = { + .name = hash_algo_name[tmr->mrs[i].mr_hash], + .bin_attrs = battrs, + }; + + mrd = tmr_dir_create(&tmr->mrs[i], pvd); + if (IS_ERR(mrd)) { + if (WARN_ONCE(PTR_ERR(mrd) == -ENOSPC, "too many banks")) + continue; + + return PTR_ERR(mrd); + } + + for (int j = 0; j < TMR_DIR_BA__COUNT; ++j) + battrs[j] = &mrd->battrs[mrd->algo][j]; + + rc = sysfs_create_group(&mrd->kobj, &agrp); + if (rc) + return rc; + } + + if (nr > 0) { + struct bin_attribute *mrfiles __free(kfree); + struct bin_attribute **battrs __free(kfree); + + mrfiles = kcalloc(nr, sizeof(*mrfiles), GFP_KERNEL); + battrs = kcalloc(nr + 1, sizeof(*battrs), GFP_KERNEL); + if (!battrs || !mrfiles) + return -ENOMEM; + + for (int i = 0, j = 0; tmr->mrs[i].mr_name; ++i) { + if (!(tmr->mrs[i].mr_flags & TSM_MR_F_F)) + continue; + + mrfiles[j].attr.name = tmr->mrs[i].mr_name; + mrfiles[j].read = tmr_digest_read; + mrfiles[j].write = tmr_digest_write; + mrfiles[j].size = tmr->mrs[i].mr_size; + mrfiles[j].private = (void *)&tmr->mrs[i]; + if (tmr->mrs[i].mr_flags & TSM_MR_F_R) + mrfiles[j].attr.mode |= S_IRUGO; + if (tmr->mrs[i].mr_flags & TSM_MR_F_W) + mrfiles[j].attr.mode |= S_IWUSR | S_IWGRP; + + battrs[j] = &mrfiles[j]; + ++j; + } + + struct attribute_group agrp = { + .bin_attrs = battrs, + }; + rc = sysfs_create_group(&pvd->kset.kobj, &agrp); + if (rc) + return rc; + + pvd->mrfiles = no_free_ptr(mrfiles); + } + + // initial refresh of MRs + rc = tmr_call_refresh(pvd, NULL); + pvd->in_sync = !rc; + + pvd = NULL; // to avoid being freed automatically + return 0; +} +EXPORT_SYMBOL_GPL(tsm_register_measurement); + +static void tmr_put_children(struct kset *kset) +{ + struct kobject *p, *n; + + spin_lock(&kset->list_lock); + list_for_each_entry_safe(p, n, &kset->list, entry) { + spin_unlock(&kset->list_lock); + kobject_put(p); + spin_lock(&kset->list_lock); + } + spin_unlock(&kset->list_lock); +} + +int tsm_unregister_measurement(struct tsm_measurement *tmr) +{ + struct kobject *kobj; + struct tmr_provider *pvd; + + kobj = kset_find_obj(tmr_sysfs_root, tmr->name); + if (!kobj) + return -ENOENT; + + pvd = container_of(kobj, typeof(*pvd), kset.kobj); + if (pvd->tmr != tmr) + return -EINVAL; + + tmr_put_children(&pvd->kset); + kset_unregister(&pvd->kset); + kobject_put(kobj); + return 0; +} +EXPORT_SYMBOL_GPL(tsm_unregister_measurement); + +int tsm_mr_init(void) +{ + tmr_sysfs_root = kset_create_and_add("tsm", NULL, kernel_kobj); + if (!tmr_sysfs_root) + return -ENOMEM; + return 0; +} + +void tsm_mr_exit(void) +{ + kset_unregister(tmr_sysfs_root); +} + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Provide Trusted Security Module measurements via sysfs"); diff --git a/include/linux/tsm.h b/include/linux/tsm.h index 11b0c525be30..312965d45001 100644 --- a/include/linux/tsm.h +++ b/include/linux/tsm.h @@ -5,6 +5,7 @@ #include #include #include +#include #define TSM_INBLOB_MAX 64 #define TSM_OUTBLOB_MAX SZ_32K @@ -109,4 +110,68 @@ struct tsm_ops { int tsm_register(const struct tsm_ops *ops, void *priv); int tsm_unregister(const struct tsm_ops *ops); + +/** + * struct tsm_measurement_register - describes an architectural measurement register (MR) + * @mr_name: name of the MR + * @mr_value: buffer containing the current value of the MR + * @mr_size: size of the MR - typically the digest size of @mr_hash + * @mr_flags: bitwise OR of flags defined in enum tsm_measurement_register_flag + * @mr_hash: optional hash identifier defined in include/uapi/linux/hash_info.h + * + * A CC guest driver provides this structure to detail the measurement facility supported by the + * underlying CC hardware. After registration via `tsm_register_measurement`, the CC guest driver + * must retain this structure until it is unregistered using `tsm_unregister_measurement`. + */ +struct tsm_measurement_register { + const char *mr_name; + void *mr_value; + u32 mr_size; + u32 mr_flags; + enum hash_algo mr_hash; +}; + +/** + * enum tsm_measurement_register_flag - properties of an MR + * @TSM_MR_F_X: this MR supports the extension semantics + * @TSM_MR_F_W: the sysfs attribute corresponding to this MR is writable + * @TSM_MR_F_R: the sysfs attribute corresponding to this MR is readable + * @TSM_MR_F_L: this MR is live - the current value may differ from the last value written so must + * be loaded back from TVM hardware/firmware on read + * @TSM_MR_F_F: present this MR as a file (instead of a directory) + * @TSM_MR_F_LIVE: shorthand for L (live) and R (readable) + * @TSM_MR_F_RTMR: shorthand for LIVE and X (extensible) + */ +enum tsm_measurement_register_flag { + TSM_MR_F_X = 1, + TSM_MR_F_W = 2, + TSM_MR_F_R = 4, + TSM_MR_F_L = 8, + TSM_MR_F_F = 16, + TSM_MR_F_LIVE = TSM_MR_F_L | TSM_MR_F_R, + TSM_MR_F_RTMR = TSM_MR_F_LIVE | TSM_MR_F_X, +}; + +#define TSM_MR_(mr, hash) \ + .mr_name = #mr, .mr_size = hash##_DIGEST_SIZE, .mr_hash = HASH_ALGO_##hash, \ + .mr_flags = TSM_MR_F_R + +/** + * struct tsm_measurement - define CC specific MRs and methods for updating them + * @name: name of the measurement provider + * @mrs: array of MR definitions ending with mr_name set to %NULL + * @refresh: sync/reload MR values in TVM hardware/firmware into the kernel buffers + * @extend: extend the specified MR with mr->mr_size bytes stored in mr->mr_value + */ +struct tsm_measurement { + const char *name; + const struct tsm_measurement_register *mrs; + int (*refresh)(struct tsm_measurement *tmr, const struct tsm_measurement_register *mr); + int (*extend)(struct tsm_measurement *tmr, const struct tsm_measurement_register *mr, + const u8 *data); +}; + +int tsm_register_measurement(struct tsm_measurement *tmr); +int tsm_unregister_measurement(struct tsm_measurement *tmr); + #endif /* __TSM_H */ -- 2.43.0