41 lines
1.4 KiB
Diff
41 lines
1.4 KiB
Diff
From: Matthew Garrett <matthew.garrett@nebula.com>
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Date: Wed, 8 Nov 2017 15:11:32 +0000
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Subject: [06/29] 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=6081db9ba435b757a3a3473d0cd50ee2252ccaeb
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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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Acked-by: Dave Young <dyoung@redhat.com>
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Reviewed-by: "Lee, Chun-Yi" <jlee@suse.com>
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Reviewed-by: James Morris <james.l.morris@oracle.com>
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cc: kexec@lists.infradead.org
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[bwh: Adjust context to apply after commit a210fd32a46b
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"kexec: add call to LSM hook in original kexec_load syscall"]
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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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--- a/kernel/kexec.c
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+++ b/kernel/kexec.c
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@@ -208,6 +208,13 @@ static inline int kexec_load_check(unsig
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return result;
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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("kexec of unsigned images"))
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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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