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| author | Ricardo Ribalda <ribalda@chromium.org> | 2023-01-04 15:38:48 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-02-03 07:50:05 +0100 |
| commit | a42aaad2e47b23d63037bfc0130e33fc0f74cd71 (patch) | |
| tree | 6b900845b9c96fbf2d9c8179ac0c3a1e6ca0ad41 /kernel/kexec.c | |
| parent | kexec: factor out kexec_load_permitted (diff) | |
| download | linux-a42aaad2e47b23d63037bfc0130e33fc0f74cd71.tar.xz linux-a42aaad2e47b23d63037bfc0130e33fc0f74cd71.zip | |
kexec: introduce sysctl parameters kexec_load_limit_*
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>
Diffstat (limited to 'kernel/kexec.c')
| -rw-r--r-- | kernel/kexec.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/kexec.c b/kernel/kexec.c index ce1bca874a8d..92d301f98776 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -190,10 +190,12 @@ out_unlock: static inline int kexec_load_check(unsigned long nr_segments, unsigned long flags) { + int image_type = (flags & KEXEC_ON_CRASH) ? + KEXEC_TYPE_CRASH : KEXEC_TYPE_DEFAULT; int result; /* We only trust the superuser with rebooting the system. */ - if (!kexec_load_permitted()) + if (!kexec_load_permitted(image_type)) return -EPERM; /* Permit LSMs and IMA to fail the kexec */ |