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Subject: [PATCH v6 0/3] kexec: Add new parameter to limit the access to kexec
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From:   Ricardo Ribalda <ribalda@chromium.org>
Date:   Wed, 04 Jan 2023 15:38:45 +0100
Message-Id: <20221114-disable-kexec-reset-v6-0-6a8531a09b9a@chromium.org>
To:     Philipp Rudo <prudo@redhat.com>,
        Eric Biederman <ebiederm@xmission.com>,
        "Guilherme G. Piccoli" <gpiccoli@igalia.com>,
        Jonathan Corbet <corbet@lwn.net>
Cc:     Ricardo Ribalda <ribalda@chromium.org>, linux-doc@vger.kernel.org,
        Sergey Senozhatsky <senozhatsky@chromium.org>,
        "Joel Fernandes (Google)" <joel@joelfernandes.org>,
        Baoquan He <bhe@redhat.com>, Petr Tesarik <petr@tesarici.cz>,
        kexec@lists.infradead.org, Bagas Sanjaya <bagasdotme@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        linux-kernel@vger.kernel.org, Ross Zwisler <zwisler@kernel.org>
Precedence: bulk

Add two parameter to specify how many times a kexec kernel can be loaded.

These parameter allow hardening the system.

While we are at it, fix a documentation issue and refactor some code.

To: Jonathan Corbet <corbet@lwn.net>
To: Eric Biederman <ebiederm@xmission.com>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: kexec@lists.infradead.org
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ross Zwisler <zwisler@kernel.org>
To: Philipp Rudo <prudo@redhat.com>
To: Guilherme G. Piccoli <gpiccoli@igalia.com>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Petr Tesarik <petr@tesarici.cz>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>

---
Changes in v6:
- Fix kexec type on kexec_file
- Match the length of the table borders to the sections underline (Thanks Bagas!)
- Fix typo on kexec_load_limit_reboot (Thanks Petr!)
- Improve commit message (Thanks Baoquan!)
- Link to v5: https://lore.kernel.org/r/20221114-disable-kexec-reset-v5-0-1bd37caf3c75@chromium.org

Changes in v5:
- Remove maxlen from ctl_table. Thanks Steven!
- Link to v4: https://lore.kernel.org/r/20221114-disable-kexec-reset-v4-0-ab809c8d988c@chromium.org

Changes in v4 (Thanks Steven!):
- Uses sysctl instead or module_parameters
- Pass image type instead of boolean to permitted
- Fix typo on flag handling
- Return -EINVAL for values that does not change the current value.
- Link to v3: https://lore.kernel.org/r/20221114-disable-kexec-reset-v3-0-4ef4e929adf6@chromium.org

Changes in v3:
- s/paramter/parameter/ Thanks Ghilherme!
- s/permited/permitted/ Thanks Joel!
- Link to v2: https://lore.kernel.org/r/20221114-disable-kexec-reset-v2-0-c498313c1bb5@chromium.org

Changes in v2:
- Instead of kexec_reboot_disabled, add two new counters (Thanks Philipp!)
- Link to v1: https://lore.kernel.org/r/20221114-disable-kexec-reset-v1-0-fb51d20cf871@chromium.org

---
Ricardo Ribalda (3):
      Documentation: sysctl: Correct kexec_load_disabled
      kexec: Factor out kexec_load_permitted
      kexec: Introduce sysctl parameters kexec_load_limit_*

 Documentation/admin-guide/sysctl/kernel.rst | 25 +++++++-
 include/linux/kexec.h                       |  3 +-
 kernel/kexec.c                              |  4 +-
 kernel/kexec_core.c                         | 94 ++++++++++++++++++++++++++++-
 kernel/kexec_file.c                         | 11 ++--
 5 files changed, 127 insertions(+), 10 deletions(-)
---
base-commit: 479174d402bcf60789106eedc4def3957c060bad
change-id: 20221114-disable-kexec-reset-19b7e117338f

Best regards,
-- 
Ricardo Ribalda <ribalda@chromium.org>