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90 lines
3.1 KiB
Diff
90 lines
3.1 KiB
Diff
From 10d1c75ed4382a8e79874379caa2ead8952734f9 Mon Sep 17 00:00:00 2001
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From: Harshit Mogalapalli <harshit.mogalapalli@oracle.com>
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Date: Tue, 30 Dec 2025 22:16:07 -0800
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Subject: [PATCH] ima: verify the previous kernel's IMA buffer lies in
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addressable RAM
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When the second-stage kernel is booted with a limiting command line (e.g.
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"mem=<size>"), the IMA measurement buffer handed over from the previous
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kernel may fall outside the addressable RAM of the new kernel. Accessing
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such a buffer can fault during early restore.
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Introduce a small generic helper, ima_validate_range(), which verifies
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that a physical [start, end] range for the previous-kernel IMA buffer lies
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within addressable memory:
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- On x86, use pfn_range_is_mapped().
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- On OF based architectures, use page_is_ram().
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Signed-off-by: Harshit Mogalapalli <harshit.mogalapalli@oracle.com>
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Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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---
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include/linux/ima.h | 1 +
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security/integrity/ima/ima_kexec.c | 35 ++++++++++++++++++++++++++++++
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2 files changed, 36 insertions(+)
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diff --git a/include/linux/ima.h b/include/linux/ima.h
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index 8e29cb4e6a01d..abf8923f8fc51 100644
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--- a/include/linux/ima.h
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+++ b/include/linux/ima.h
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@@ -69,6 +69,7 @@ static inline int ima_measure_critical_data(const char *event_label,
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#ifdef CONFIG_HAVE_IMA_KEXEC
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int __init ima_free_kexec_buffer(void);
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int __init ima_get_kexec_buffer(void **addr, size_t *size);
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+int ima_validate_range(phys_addr_t phys, size_t size);
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#endif
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#ifdef CONFIG_IMA_SECURE_AND_OR_TRUSTED_BOOT
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diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
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index 5beb69edd12fd..36a34c54de58b 100644
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--- a/security/integrity/ima/ima_kexec.c
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+++ b/security/integrity/ima/ima_kexec.c
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@@ -12,6 +12,8 @@
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#include <linux/kexec.h>
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#include <linux/of.h>
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#include <linux/ima.h>
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+#include <linux/mm.h>
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+#include <linux/overflow.h>
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#include <linux/reboot.h>
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#include <asm/page.h>
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#include "ima.h"
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@@ -294,3 +296,36 @@ void __init ima_load_kexec_buffer(void)
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pr_debug("Error restoring the measurement list: %d\n", rc);
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}
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}
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+
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+/*
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+ * ima_validate_range - verify a physical buffer lies in addressable RAM
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+ * @phys: physical start address of the buffer from previous kernel
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+ * @size: size of the buffer
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+ *
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+ * On success return 0. On failure returns -EINVAL so callers can skip
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+ * restoring.
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+ */
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+int ima_validate_range(phys_addr_t phys, size_t size)
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+{
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+ unsigned long start_pfn, end_pfn;
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+ phys_addr_t end_phys;
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+
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+ if (check_add_overflow(phys, (phys_addr_t)size - 1, &end_phys))
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+ return -EINVAL;
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+
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+ start_pfn = PHYS_PFN(phys);
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+ end_pfn = PHYS_PFN(end_phys);
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+
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+#ifdef CONFIG_X86
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+ if (!pfn_range_is_mapped(start_pfn, end_pfn))
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+#else
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+ if (!page_is_ram(start_pfn) || !page_is_ram(end_pfn))
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+#endif
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+ {
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+ pr_warn("IMA: previous kernel measurement buffer %pa (size 0x%zx) lies outside available memory\n",
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+ &phys, size);
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+ return -EINVAL;
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+ }
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+
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+ return 0;
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+}
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--
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2.51.0
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