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kexec allows replacing the current kernel with a different one. This is usually a source of concerns for sysadmins that want to harden a system. Linux already provides a way to disable loading new kexec kernel via kexec_load_disabled, but that control is very coard, it is all or nothing and does not make distinction between a panic kexec and a normal kexec. This patch introduces new sysctl parameters, with finer tuning to specify how many times a kexec kernel can be loaded. The sysadmin can set different limits for kexec panic and kexec reboot kernels. The value can be modified at runtime via sysctl, but only with a stricter value. With these new parameters on place, a system with loadpin and verity enabled, using the following kernel parameters: sysctl.kexec_load_limit_reboot=0 sysct.kexec_load_limit_panic=1 can have a good warranty that if initrd tries to load a panic kernel, a malitious user will have small chances to replace that kernel with a different one, even if they can trigger timeouts on the disk where the panic kernel lives. Link: https://lkml.kernel.org/r/20221114-disable-kexec-reset-v6-3-6a8531a09b9a@chromium.org Signed-off-by: Ricardo Ribalda <ribalda@chromium.org> Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org> Acked-by: Baoquan He <bhe@redhat.com> Cc: Bagas Sanjaya <bagasdotme@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck Cc: Joel Fernandes (Google) <joel@joelfernandes.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Philipp Rudo <prudo@redhat.com> Cc: Ross Zwisler <zwisler@kernel.org> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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| ABI | ||
| accel | ||
| accounting | ||
| admin-guide | ||
| arc | ||
| arm | ||
| arm64 | ||
| block | ||
| bpf | ||
| cdrom | ||
| core-api | ||
| cpu-freq | ||
| crypto | ||
| dev-tools | ||
| devicetree | ||
| doc-guide | ||
| driver-api | ||
| fault-injection | ||
| fb | ||
| features | ||
| filesystems | ||
| firmware_class | ||
| firmware-guide | ||
| fpga | ||
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| hid | ||
| hwmon | ||
| i2c | ||
| ia64 | ||
| iio | ||
| images | ||
| infiniband | ||
| input | ||
| isdn | ||
| kbuild | ||
| kernel-hacking | ||
| leds | ||
| litmus-tests | ||
| livepatch | ||
| locking | ||
| loongarch | ||
| m68k | ||
| maintainer | ||
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| misc-devices | ||
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| netlabel | ||
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| PCI | ||
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| power | ||
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| process | ||
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| rust | ||
| s390 | ||
| scheduler | ||
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| security | ||
| sh | ||
| sound | ||
| sparc | ||
| sphinx | ||
| sphinx-static | ||
| spi | ||
| staging | ||
| target | ||
| timers | ||
| tools | ||
| trace | ||
| translations | ||
| usb | ||
| userspace-api | ||
| virt | ||
| w1 | ||
| watchdog | ||
| x86 | ||
| xtensa | ||
| .gitignore | ||
| arch.rst | ||
| atomic_bitops.txt | ||
| atomic_t.txt | ||
| Changes | ||
| CodingStyle | ||
| conf.py | ||
| docutils.conf | ||
| dontdiff | ||
| index.rst | ||
| Kconfig | ||
| Makefile | ||
| memory-barriers.txt | ||
| SubmittingPatches | ||
| subsystem-apis.rst | ||