From: AKASHI Takahiro <takahiro.akashi@linaro.org>
To: catalin.marinas@arm.com, will.deacon@arm.com,
bauerman@linux.vnet.ibm.com, dhowells@redhat.com,
vgoyal@redhat.com, herbert@gondor.apana.org.au,
davem@davemloft.net, akpm@linux-foundation.org,
mpe@ellerman.id.au, dyoung@redhat.com, bhe@redhat.com,
arnd@arndb.de, ard.biesheuvel@linaro.org, julien.thierry@arm.com
Cc: kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
AKASHI Takahiro <takahiro.akashi@linaro.org>
Subject: [PATCH v8 13/13] arm64: kexec_file: enable KEXEC_VERIFY_SIG for Image
Date: Thu, 22 Feb 2018 20:17:32 +0900 [thread overview]
Message-ID: <20180222111732.23051-14-takahiro.akashi@linaro.org> (raw)
In-Reply-To: <20180222111732.23051-1-takahiro.akashi@linaro.org>
With this patch, kernel verification can be done without IMA security
subsystem enabled. Turn on CONFIG_KEXEC_VERIFY_SIG instead.
On x86, a signature is embedded into a PE file (Microsoft's format) header
of binary. Since arm64's "Image" can also be seen as a PE file as far as
CONFIG_EFI is enabled, we adopt this format for kernel signing.
You can create a signed kernel image with:
$ sbsign --key ${KEY} --cert ${CERT} Image
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/Kconfig | 24 ++++++++++++++++++++++++
arch/arm64/include/asm/kexec.h | 16 ++++++++++++++++
arch/arm64/kernel/kexec_image.c | 15 +++++++++++++++
3 files changed, 55 insertions(+)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 79ee27b8d2a0..e400edc291d4 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -839,6 +839,30 @@ config KEXEC_FILE
for kernel and initramfs as opposed to list of segments as
accepted by previous system call.
+config KEXEC_VERIFY_SIG
+ bool "Verify kernel signature during kexec_file_load() syscall"
+ depends on KEXEC_FILE
+ ---help---
+ Select this option to verify a signature with loaded kernel
+ image. If configured, any attempt of loading a image without
+ valid signature will fail.
+
+ In addition to that option, you need to enable signature
+ verification for the corresponding kernel image type being
+ loaded in order for this to work.
+
+config KEXEC_IMAGE_VERIFY_SIG
+ bool "Enable Image signature verification support"
+ default y
+ depends on KEXEC_VERIFY_SIG
+ depends on EFI && SIGNED_PE_FILE_VERIFICATION
+ ---help---
+ Enable Image signature verification support.
+
+comment "Image signature verification is missing yet"
+ depends on KEXEC_VERIFY_SIG
+ depends on !EFI || !SIGNED_PE_FILE_VERIFICATION
+
config CRASH_DUMP
bool "Build kdump crash kernel"
help
diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
index 592890085aae..85f6913f868f 100644
--- a/arch/arm64/include/asm/kexec.h
+++ b/arch/arm64/include/asm/kexec.h
@@ -132,6 +132,7 @@ struct arm64_image_header {
};
static const u8 arm64_image_magic[4] = {'A', 'R', 'M', 0x64U};
+static const u8 arm64_image_pe_sig[2] = {'M', 'Z'};
/**
* arm64_header_check_magic - Helper to check the arm64 image header.
@@ -153,6 +154,21 @@ static inline int arm64_header_check_magic(const struct arm64_image_header *h)
&& h->magic[3] == arm64_image_magic[3]);
}
+/**
+ * arm64_header_check_pe_sig - Helper to check the arm64 image header.
+ *
+ * Returns non-zero if 'MZ' signature is found.
+ */
+
+static inline int arm64_header_check_pe_sig(const struct arm64_image_header *h)
+{
+ if (!h)
+ return 0;
+
+ return (h->pe_sig[0] == arm64_image_pe_sig[0]
+ && h->pe_sig[1] == arm64_image_pe_sig[1]);
+}
+
extern const struct kexec_file_ops kexec_image_ops;
struct kimage;
diff --git a/arch/arm64/kernel/kexec_image.c b/arch/arm64/kernel/kexec_image.c
index de62def63dd6..816d5faf491d 100644
--- a/arch/arm64/kernel/kexec_image.c
+++ b/arch/arm64/kernel/kexec_image.c
@@ -15,6 +15,7 @@
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/kexec.h>
+#include <linux/verification.h>
#include <asm/byteorder.h>
#include <asm/memory.h>
@@ -27,6 +28,9 @@ static int image_probe(const char *kernel_buf, unsigned long kernel_len)
if ((kernel_len < sizeof(*h)) || !arm64_header_check_magic(h))
return -EINVAL;
+ pr_debug("PE format: %s\n",
+ (arm64_header_check_pe_sig(h) ? "yes" : "no"));
+
return 0;
}
@@ -84,7 +88,18 @@ static void *image_load(struct kimage *image, char *kernel,
return ERR_PTR(ret);
}
+#ifdef CONFIG_KEXEC_IMAGE_VERIFY_SIG
+static int image_verify_sig(const char *kernel, unsigned long kernel_len)
+{
+ return verify_pefile_signature(kernel, kernel_len, NULL,
+ VERIFYING_KEXEC_PE_SIGNATURE);
+}
+#endif
+
const struct kexec_file_ops kexec_image_ops = {
.probe = image_probe,
.load = image_load,
+#ifdef CONFIG_KEXEC_IMAGE_VERIFY_SIG
+ .verify_sig = image_verify_sig,
+#endif
};
--
2.16.2
next prev parent reply other threads:[~2018-02-22 11:20 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-22 11:17 [PATCH v8 00/13] arm64: kexec: add kexec_file_load() support AKASHI Takahiro
2018-02-22 11:17 ` [PATCH v8 01/13] resource: add walk_system_ram_res_rev() AKASHI Takahiro
2018-02-23 8:36 ` Dave Young
2018-03-20 1:43 ` Baoquan He
2018-03-20 3:12 ` AKASHI Takahiro
2018-03-20 3:48 ` Baoquan He
2018-02-22 11:17 ` [PATCH v8 02/13] kexec_file: make an use of purgatory optional AKASHI Takahiro
2018-02-23 8:49 ` Dave Young
2018-02-26 10:24 ` AKASHI Takahiro
2018-02-28 12:33 ` Dave Young
2018-03-01 2:59 ` AKASHI Takahiro
2018-02-22 11:17 ` [PATCH v8 03/13] kexec_file,x86,powerpc: factor out kexec_file_ops functions AKASHI Takahiro
2018-02-23 9:24 ` Dave Young
2018-02-26 10:01 ` AKASHI Takahiro
2018-02-26 11:25 ` Philipp Rudo
2018-02-28 12:38 ` Dave Young
2018-03-01 3:18 ` AKASHI Takahiro
2018-02-26 11:17 ` [PATCH v8 03/13] kexec_file, x86, powerpc: " Philipp Rudo
2018-02-27 2:03 ` AKASHI Takahiro
2018-02-27 9:26 ` Philipp Rudo
2018-02-22 11:17 ` [PATCH v8 04/13] x86: kexec_file: factor out elf core header related functions AKASHI Takahiro
2018-02-24 3:15 ` Dave Young
2018-02-26 9:21 ` AKASHI Takahiro
2018-02-22 11:17 ` [PATCH v8 05/13] kexec_file, x86: move re-factored code to generic side AKASHI Takahiro
2018-02-22 11:17 ` [PATCH v8 06/13] asm-generic: add kexec_file_load system call to unistd.h AKASHI Takahiro
2018-02-22 11:17 ` [PATCH v8 07/13] arm64: kexec_file: invoke the kernel without purgatory AKASHI Takahiro
2018-02-22 11:17 ` [PATCH v8 08/13] arm64: kexec_file: load initrd and device-tree AKASHI Takahiro
2018-02-22 11:17 ` [PATCH v8 09/13] arm64: kexec_file: add crash dump support AKASHI Takahiro
2018-02-22 11:17 ` [PATCH v8 10/13] arm64: kexec_file: add Image format support AKASHI Takahiro
2018-02-22 11:17 ` [PATCH v8 11/13] arm64: kexec_file: enable KEXEC_FILE config AKASHI Takahiro
2018-02-22 11:17 ` [PATCH v8 12/13] include: pe.h: remove message[] from mz header definition AKASHI Takahiro
2018-02-22 11:17 ` AKASHI Takahiro [this message]
2018-02-27 4:56 ` [PATCH v8 00/13] arm64: kexec: add kexec_file_load() support AKASHI Takahiro
2018-02-28 12:25 ` Dave Young
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