[PATCH 3/3] powerpc/kexec_file: Add KEXEC_SIG support.

Michal Suchanek
2021-11-03T14:27:19Z

Use the module verifier for the kernel image verification.

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
---
arch/powerpc/Kconfig | 11 +++++++++++
arch/powerpc/kexec/elf_64.c | 14 ++++++++++++++
2 files changed, 25 insertions(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 743c9783c64f..27bffafa9e79 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -558,6 +558,17 @@ config KEXEC_FILE
config ARCH_HAS_KEXEC_PURGATORY
def_bool KEXEC_FILE

+config KEXEC_SIG
+ bool "Verify kernel signature during kexec_file_load() syscall"
+ depends on KEXEC_FILE && MODULE_SIG_FORMAT
+ help
+ This option makes kernel signature verification mandatory for
+ the kexec_file_load() syscall.
+
+ 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 PPC64_BUILD_ELF_V2_ABI
bool

diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c
index eeb258002d1e..e8dff6b23ac5 100644
--- a/arch/powerpc/kexec/elf_64.c
+++ b/arch/powerpc/kexec/elf_64.c
@@ -23,6 +23,7 @@
#include <linux/of_fdt.h>
#include <linux/slab.h>
#include <linux/types.h>
+#include <linux/verification.h>

static void *elf64_load(struct kimage *image, char *kernel_buf,
unsigned long kernel_len, char *initrd,
@@ -151,7 +152,20 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
return ret ? ERR_PTR(ret) : NULL;
}

+#ifdef CONFIG_KEXEC_SIG
+int elf64_verify_sig(const char *kernel, unsigned long length)
+{
+ size_t kernel_len = length;
+
+ return verify_appended_signature(kernel, &kernel_len, VERIFY_USE_PLATFORM_KEYRING,
+ "kexec_file");
+}
+#endif /* CONFIG_KEXEC_SIG */
+
const struct kexec_file_ops kexec_elf64_ops = {
.probe = kexec_elf_probe,
.load = elf64_load,
+#ifdef CONFIG_KEXEC_SIG
+ .verify_sig = elf64_verify_sig,
+#endif
};
--
2.31.1