37 lines
1.2 KiB
Diff
37 lines
1.2 KiB
Diff
From: Matthew Garrett <matthew.garrett@nebula.com>
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Date: Wed, 5 Apr 2017 17:40:30 +0100
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Subject: [45/62] kexec: Disable at runtime if the kernel is locked down
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Origin: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/commit?id=e7c340d3a52b23631aa5e67cd10eac766042db50
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kexec permits the loading and execution of arbitrary code in ring 0, which
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is something that lock-down is meant to prevent. It makes sense to disable
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kexec in this situation.
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This does not affect kexec_file_load() which can check for a signature on the
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image to be booted.
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Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
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Signed-off-by: David Howells <dhowells@redhat.com>
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---
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kernel/kexec.c | 7 +++++++
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1 file changed, 7 insertions(+)
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diff --git a/kernel/kexec.c b/kernel/kexec.c
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index 980936a90ee6..46de8e6b42f4 100644
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--- a/kernel/kexec.c
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+++ b/kernel/kexec.c
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@@ -194,6 +194,13 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
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return -EPERM;
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/*
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+ * kexec can be used to circumvent module loading restrictions, so
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+ * prevent loading in that case
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+ */
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+ if (kernel_is_locked_down())
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+ return -EPERM;
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+
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+ /*
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* Verify we have a legal set of flags
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* This leaves us room for future extensions.
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*/
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