From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794209679; b=xeFnU4l12ecPRY39iwIBeZL/KkvFS2uTdvvQFrux4QOrRj9dl9GAAM+g0SBjVXXz31Cc CZSDf7TRjbvEfnvAk6QlaKFVlBIeicWBJRkbGnvR3uv6vdmh8zkSxwBzVAvT+OEWjmOmW 3b0w43cWJgN/azVcFPfZRkD+obgWWCH717bv+56ohc4Aov7ibl7cxwCFoLzCswqtKT34K R5s/xBGXvrredI/9RZYmx0Qvh71SpLitRypT8m8VzaoPBobGlfJ3/lcloVDekD5z9XfMU ghqodsCFyc2xa2scT0ky+Ubb5EKVdEREfID55OfYHX+248ZdjPgyCy953PJWAbLjaRA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794209679; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Type:X-Mailer: Content-Transfer-Encoding; bh=4rGATcdkFHVDIIsPGWAGyVXOOtm1+i4aQGdQVAamHuU=; b=TJ5FUMSQHfw1Pgg2NXf7206cRaFfoqtxdtidPBlkrqQqALEnEoqhA0cc5wWLEhr50hkx sGyIS3Sc5gLuh7QdidU1tEzmlO+Z8OQ2QsmesIm99sJNOY2Em3W40vxQ57imBSuAbBM6C ATGZ4OeOVEHpE4utGLk64oyJCy9BBD/tx3pj7gdOjT1RJkcbKShvLVz5KNtCdxkJe9Mdu 1xXryzmMoi7AjuBUfKOhIWQYXU5WvG0RJpcn8YnkaMtlt8hp2j+V/c8jTKq9y8np2w76B SYYmet6aNY0P4IoZ5qhxP+w5GKBZ8a/+ffUhad17LvROWMDPYSw4eMjhwTrb8XNLjow== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=L6t12SSh; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 80D9D60A5BE8; Mon, 9 Nov 2026 07:34:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=L6t12SSh Received: by smtp.kernel.org (Postfix) with ESMTPSA id 660881F0089F; Mon, 9 Nov 2026 07:34:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794209679; bh=4rGATcdkFHVDIIsPGWAGyVXOOtm1+i4aQGdQVAamHuU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=L6t12SShyoy5fNLsK/7yt58iOBG+vbCkNSlA+3QJHMQS8lIxj9xFIAv6fZFfOUD3o xxgJArlgj9nXSzNipTYmebMXsABKSz+uuT3y3lfH4ZjoVmxrRBmnrEDHPaoDl1Oa1l y5jh5WsHe3HuEQG4ha3jOolF1Jwdyb9Qzmr+XzykaZnQIIlrO1PLGTh/xPwN/bHOSz CGEQXpCjE+Zv32fz0kUOtLM+oLGrO8JDSX5jbBpmD/N1aa4iMrwAt0LXiw390WQYK8 D1Yt4fGOn39iPRnLGybIobRgeKyRBhrh712cCy+p+0WGf0aIP4/3ZqhxWNPZv3FHi8 JpCkXhmR1XvhA== From: Leon Romanovsky To: Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich , Dmitry Torokhov , Andrew Lunn , Heiner Kallweit , Russell King , "David S. Miller" , Jakub Kicinski , Paolo Abeni , Johannes Berg , Jonathan Corbet , Shuah Khan , Randy Dunlap , Bjorn Helgaas , "Joerg Roedel (AMD)" , Suravee Suthikulpanit , Vasant Hegde , Will Deacon , Robin Murphy , David Woodhouse , Lu Baolu , Johan Hovold , Eric Dumazet , Marcel Holtmann , Luiz Augusto von Dentz , Nipun Gupta , Nikhil Agarwal , Pieter Jansen van Vuuren Cc: linux-kernel@vger.kernel.org, driver-core@lists.linux.dev, linux-input@vger.kernel.org, netdev@vger.kernel.org, linux-wireless@vger.kernel.org, linux-usb@vger.kernel.org, linux-bluetooth@vger.kernel.org, linux-acpi@vger.kernel.org, linux-doc@vger.kernel.org, linux-pci@vger.kernel.org, iommu@lists.linux.dev, Jason Gunthorpe Subject: [PATCH v2 12/19] driver core: Expose device trust authorization interfaces Date: Mon, 9 Nov 2026 09:33:42 +0200 Message-ID: <20261109-device-trust-core-v2-12-3b12d9a9f861@nvidia.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261109-device-trust-core-v2-0-3b12d9a9f861@nvidia.com> References: <20261109-device-trust-core-v2-0-3b12d9a9f861@nvidia.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" X-Mailer: b4 0.15-dev-18f8f Content-Transfer-Encoding: 8bit From: Leon Romanovsky An initrd must authorize a disabled device after attestation even if a built-in driver already attempted to probe it. Buses with their own authorization interface need to apply the same policy rules. Expose requested policy and active trust through sysfs, and export device_trust_set_policy() for bus authorization. Fix explicit authorization or commitment for the device lifetime and serialize writes with probing. Under the global full policy, reject changes and leave same-value writes as no-ops so manual attachment needs no additional lock. Include the attributes in device ownership changes. Signed-off-by: Leon Romanovsky --- Documentation/ABI/testing/sysfs-devices-trust | 28 +++++++ Documentation/admin-guide/kernel-parameters.txt | 1 + MAINTAINERS | 1 + drivers/base/base.h | 2 + drivers/base/core.c | 15 +++- drivers/base/trust.c | 106 ++++++++++++++++++++++++ include/linux/device.h | 5 ++ include/linux/device/trust.h | 1 + 8 files changed, 158 insertions(+), 1 deletion(-) diff --git a/Documentation/ABI/testing/sysfs-devices-trust b/Documentation/ABI/testing/sysfs-devices-trust new file mode 100644 index 0000000000000..d68113b0d6b08 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-devices-trust @@ -0,0 +1,28 @@ +What: /sys/devices/.../trust +Date: September 2026 +Contact: driver-core@lists.linux.dev +Description: + (RO) The active trust level for the device. The values are + "disabled", "adversary", and "full". Driver core resolves + the level before probe, and retains it through whole lifetime. + +What: /sys/devices/.../trust_policy +Date: September 2026 +Contact: driver-core@lists.linux.dev +Description: + (RW) The requested trust policy for the device. The initial + value may be selected by the bus before the device is + registered; otherwise it is "default". The policy is resolved + to an active trust level before the device is probed. + + The values are "default", "disabled", "adversary", and + "full". "default" lets the bus select the active trust level. + "disabled" prevents a driver from binding and informs the kernel + to provide containtment of the device. For example a PCIe device + should be unable to DMA to the memory. "adversary" informs the + kernel that the userspace wants to opt into any security + defences the kernel may have to restrict and further validate + interactions with the device. This may have a performance or + functional cost compared to "full". As an example the DMA API + and IOMMU layers will avoid exposing unrelated nearby memory + to the device during DMA. "full" requests normal operation. diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 81a936dca9476..2d046c79becd9 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1266,6 +1266,7 @@ Kernel parameters Other values replace bus policy. The last valid value wins. Full-only manual driver attachment requires full; other global policies reject it before the probe callback. + With full, runtime trust policy changes are unavailable. dfltcc= [HW,S390] Format: { on | off | def_only | inf_only | always } diff --git a/MAINTAINERS b/MAINTAINERS index b726344362b41..a145aaaca2ef3 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8150,6 +8150,7 @@ L: driver-core@lists.linux.dev S: Supported T: git git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core.git F: Documentation/ABI/testing/sysfs-bus-drivers-probe +F: Documentation/ABI/testing/sysfs-devices-trust F: Documentation/core-api/kobject.rst F: Documentation/driver-api/driver-model/ F: drivers/base/ diff --git a/drivers/base/base.h b/drivers/base/base.h index ba8b5b3c51a65..623444c7a3be8 100644 --- a/drivers/base/base.h +++ b/drivers/base/base.h @@ -176,6 +176,8 @@ void bus_remove_driver(struct device_driver *drv); void device_release_driver_internal(struct device *dev, const struct device_driver *drv, struct device *parent); +extern const struct attribute_group device_trust_attr_group; + /* Full-only manual attachment uses the caller's subsystem serialization. */ void device_trust_init_state(struct device *dev); int device_trust_prepare(struct device *dev, const struct device_driver *drv); diff --git a/drivers/base/core.c b/drivers/base/core.c index 6b94a163cda8d..bd96d84c2ac2c 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -2989,10 +2989,14 @@ static int device_add_attrs(struct device *dev) if (error) goto err_remove_type_groups; + error = device_add_group(dev, &device_trust_attr_group); + if (error) + goto err_remove_dev_groups; + if (device_supports_offline(dev) && !dev_offline_disabled(dev)) { error = device_create_file(dev, &dev_attr_online); if (error) - goto err_remove_dev_groups; + goto err_remove_dev_trust_group; } if (fw_devlink_flags && !fw_devlink_is_permissive() && dev->fwnode) { @@ -3022,6 +3026,8 @@ static int device_add_attrs(struct device *dev) device_remove_file(dev, &dev_attr_waiting_for_supplier); err_remove_dev_online: device_remove_file(dev, &dev_attr_online); + err_remove_dev_trust_group: + device_remove_group(dev, &device_trust_attr_group); err_remove_dev_groups: device_remove_groups(dev, dev->groups); err_remove_type_groups: @@ -3047,6 +3053,7 @@ static void device_remove_attrs(struct device *dev) device_remove_file(dev, &dev_attr_removable); device_remove_file(dev, &dev_attr_waiting_for_supplier); device_remove_file(dev, &dev_attr_online); + device_remove_group(dev, &device_trust_attr_group); device_remove_groups(dev, dev->groups); if (type) @@ -4791,6 +4798,12 @@ static int device_attrs_change_owner(struct device *dev, kuid_t kuid, if (error) return error; + /* Change the trust attributes of @dev to @kuid/@kgid. */ + error = sysfs_group_change_owner(kobj, &device_trust_attr_group, kuid, + kgid); + if (error) + return error; + if (device_supports_offline(dev) && !dev_offline_disabled(dev)) { /* Change online device attributes of @dev to @kuid/@kgid. */ error = sysfs_file_change_owner(kobj, dev_attr_online.attr.name, diff --git a/drivers/base/trust.c b/drivers/base/trust.c index 6a71abf10b3bb..86ce2751f30a3 100644 --- a/drivers/base/trust.c +++ b/drivers/base/trust.c @@ -5,6 +5,7 @@ #include #include #include +#include #include #include "base.h" @@ -105,6 +106,111 @@ static const char * const device_trust_policy_names[] = { [DEVICE_TRUST_POLICY_FULL] = "full", }; +static const char * const device_trust_level_names[] = { + [DEVICE_TRUST_DISABLED] = "disabled", + [DEVICE_TRUST_ADVERSARY] = "adversary", + [DEVICE_TRUST_FULL] = "full", +}; + +static ssize_t trust_show(struct device *dev, + const struct device_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%s\n", + device_trust_level_names[device_get_trust_level(dev)]); +} +static DEVICE_ATTR_RO(trust); + +static ssize_t trust_policy_show(struct device *dev, + const struct device_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%s\n", + device_trust_policy_names[READ_ONCE(dev->trust_policy)]); +} + +/** + * device_trust_set_policy - Request a trust policy for a device + * @dev: registered device + * @policy: requested policy + * + * Apply the same rules as a write to the device's trust_policy attribute. + * A bus can use this to translate its own authorization interface into + * device trust. Takes the device lock except when the global full policy + * makes runtime policy changes unavailable. In that mode, writing the current + * policy is a no-op. + * + * Return: 0 on success, -EBUSY if the policy can no longer change, -ENODEV + * if the device is being removed outside global full mode. + */ +int device_trust_set_policy(struct device *dev, enum device_trust_policy policy) +{ + int ret = 0; + + if (device_trust_default_policy == DEVICE_TRUST_POLICY_FULL) + return policy == READ_ONCE(dev->trust_policy) ? 0 : -EBUSY; + + device_lock(dev); + if (dev->p->dead) { + ret = -ENODEV; + goto unlock; + } + if (policy == dev->trust_policy) + goto unlock; + + /* A driver that claimed the device before registration was not admitted. */ + if (READ_ONCE(dev->driver)) { + ret = -EBUSY; + goto unlock; + } + + switch (dev->p->trust_state) { + case DEVICE_TRUST_SELECTABLE: + if (policy == DEVICE_TRUST_POLICY_DISABLED) + dev->p->trust_state = DEVICE_TRUST_WAITING; + break; + case DEVICE_TRUST_WAITING: + if (policy != DEVICE_TRUST_POLICY_ADVERSARY && + policy != DEVICE_TRUST_POLICY_FULL) { + ret = -EBUSY; + goto unlock; + } + dev->p->trust_state = DEVICE_TRUST_AUTHORIZED; + break; + default: + ret = -EBUSY; + goto unlock; + } + WRITE_ONCE(dev->trust_policy, policy); +unlock: + device_unlock(dev); + return ret; +} +EXPORT_SYMBOL_GPL(device_trust_set_policy); + +static ssize_t trust_policy_store(struct device *dev, + const struct device_attribute *attr, + const char *buf, size_t count) +{ + int policy, ret; + + policy = sysfs_match_string(device_trust_policy_names, buf); + if (policy < 0) + return policy; + + ret = device_trust_set_policy(dev, policy); + + return ret ? ret : count; +} +static DEVICE_ATTR_RW(trust_policy); + +static struct attribute *device_trust_attrs[] = { + &dev_attr_trust.attr, + &dev_attr_trust_policy.attr, + NULL, +}; + +const struct attribute_group device_trust_attr_group = { + .attrs = device_trust_attrs, +}; static int __init device_trust_default_setup(char *str) { int policy = match_string(device_trust_policy_names, diff --git a/include/linux/device.h b/include/linux/device.h index 57d2e1b0d98ad..e3e7457cd50f4 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -933,6 +933,11 @@ static inline bool device_iommu_mapped(struct device *dev) return (dev->iommu_group != NULL); } +static inline bool device_policy_is_disabled(const struct device *dev) +{ + return READ_ONCE(dev->trust_policy) == DEVICE_TRUST_POLICY_DISABLED; +} + /* Get the wakeup routines, which depend on struct device */ #include diff --git a/include/linux/device/trust.h b/include/linux/device/trust.h index b8f5514cacec3..eb36970289e84 100644 --- a/include/linux/device/trust.h +++ b/include/linux/device/trust.h @@ -38,6 +38,7 @@ enum device_trust_policy { }; void device_trust_init(struct device *dev); +int device_trust_set_policy(struct device *dev, enum device_trust_policy policy); enum device_trust_level device_get_trust_level(const struct device *dev); bool device_is_adversarial(const struct device *dev); -- 2.56.0