Dmitry Safonov d7bd8cf0b3 ima_fs: Correctly create securityfs files for unsupported hash algos
ima_tpm_chip->allocated_banks[i].crypto_id is initialized to
HASH_ALGO__LAST if the TPM algorithm is not supported. However there
are places relying on the algorithm to be valid because it is accessed
by hash_algo_name[].

On 6.12.40 I observe the following read out-of-bounds in hash_algo_name:
  ==================================================================
  BUG: KASAN: global-out-of-bounds in create_securityfs_measurement_lists+0x396/0x440
  Read of size 8 at addr ffffffff83e18138 by task swapper/0/1

  CPU: 4 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.12.40 #3
  Call Trace:
   <TASK>
   dump_stack_lvl+0x61/0x90
   print_report+0xc4/0x580
   ? kasan_addr_to_slab+0x26/0x80
   ? create_securityfs_measurement_lists+0x396/0x440
   kasan_report+0xc2/0x100
   ? create_securityfs_measurement_lists+0x396/0x440
   create_securityfs_measurement_lists+0x396/0x440
   ima_fs_init+0xa3/0x300
   ima_init+0x7d/0xd0
   init_ima+0x28/0x100
   do_one_initcall+0xa6/0x3e0
   kernel_init_freeable+0x455/0x740
   kernel_init+0x24/0x1d0
   ret_from_fork+0x38/0x80
   ret_from_fork_asm+0x11/0x20
   </TASK>

  The buggy address belongs to the variable:
   hash_algo_name+0xb8/0x420

  Memory state around the buggy address:
   ffffffff83e18000: 00 01 f9 f9 f9 f9 f9 f9 00 01 f9 f9 f9 f9 f9 f9
   ffffffff83e18080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  >ffffffff83e18100: 00 00 00 00 00 00 00 f9 f9 f9 f9 f9 00 05 f9 f9
                                          ^
   ffffffff83e18180: f9 f9 f9 f9 00 00 00 00 00 00 00 04 f9 f9 f9 f9
   ffffffff83e18200: 00 00 00 00 00 00 00 00 04 f9 f9 f9 f9 f9 f9 f9
  ==================================================================

Seems like the TPM chip supports sha3_256, which isn't yet in
tpm_algorithms:
  tpm tpm0: TPM with unsupported bank algorithm 0x0027

That's TPM_ALG_SHA3_256 == 0x0027 from "Trusted Platform Module 2.0
Library Part 2: Structures", page 51 [1].
See also the related U-Boot algorithms update [2].

Thus solve the problem by creating a file name with "_tpm_alg_<ID>"
postfix if the crypto algorithm isn't initialized.

This is how it looks on the test machine (patch ported to v6.12 release):
  # ls -1 /sys/kernel/security/ima/
  ascii_runtime_measurements
  ascii_runtime_measurements_tpm_alg_27
  ascii_runtime_measurements_sha1
  ascii_runtime_measurements_sha256
  binary_runtime_measurements
  binary_runtime_measurements_tpm_alg_27
  binary_runtime_measurements_sha1
  binary_runtime_measurements_sha256
  policy
  runtime_measurements_count
  violations

[1]: https://trustedcomputinggroup.org/wp-content/uploads/Trusted-Platform-Module-2.0-Library-Part-2-Version-184_pub.pdf
[2]: https://lists.denx.de/pipermail/u-boot/2024-July/558835.html

Fixes: 9fa8e76250 ("ima: add crypto agility support for template-hash algorithm")
Signed-off-by: Dmitry Safonov <dima@arista.com>
Cc: Enrico Bravi <enrico.bravi@polito.it>
Cc: Silvia Sisinni <silvia.sisinni@polito.it>
Cc: Roberto Sassu <roberto.sassu@huawei.com>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Roberto Sassu <roberto.sassu@huawei.com>
Tested-by: Roberto Sassu <roberto.sassu@huawei.com>
Link: https://github.com/linux-integrity/linux/issues/14
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2026-03-11 14:24:46 -04:00
2026-02-28 15:31:35 +01:00
2026-01-26 19:07:09 -08:00
2022-09-28 09:02:20 +02:00
2025-02-19 14:53:27 -07:00
2026-03-01 15:39:31 -08:00

Linux kernel
============

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer - Getting started with kernel development
* Academic Researcher - Studying kernel internals and architecture
* Security Expert - Hardening and vulnerability analysis
* Backport/Maintenance Engineer - Maintaining stable kernels
* System Administrator - Configuring and troubleshooting
* Maintainer - Leading subsystems and reviewing patches
* Hardware Vendor - Writing drivers for new hardware
* Distribution Maintainer - Packaging kernels for distros
* AI Coding Assistant - LLMs and AI-powered development tools


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst
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