[PATCH v6 3/3] arm64: Add IMA kexec buffer to DTB

Lakshmi Ramasubramanian
2020-09-08T23:09:31Z

Any existing FDT_PROP_IMA_KEXEC_BUFFER property in the device tree
needs to be removed and its corresponding memory reservation in
the currently running kernel needs to be freed.

The address and size of the current kernel's IMA measurement log need
to be added to the device tree's IMA kexec buffer node and memory for
the buffer needs to be reserved for the log to be carried over to
the next kernel on the kexec call.

Remove any existing FDT_PROP_IMA_KEXEC_BUFFER property in the device
tree and free the corresponding memory reservation in the currently
running kernel. Add FDT_PROP_IMA_KEXEC_BUFFER property to the device
tree and reserve the memory for storing the IMA log.
Update CONFIG_KEXEC_FILE to select CONFIG_HAVE_IMA_KEXEC to indicate
that the IMA measurement log information is present in the device tree
for ARM64.

Co-developed-by: Prakhar Srivastava <prsriva@linux.microsoft.com>
Signed-off-by: Prakhar Srivastava <prsriva@linux.microsoft.com>
Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
---
arch/arm64/Kconfig | 1 +
arch/arm64/kernel/machine_kexec_file.c | 18 ++++++++++++++++++
2 files changed, 19 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 6d232837cbee..9f03c8245e5b 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1077,6 +1077,7 @@ config KEXEC
config KEXEC_FILE
bool "kexec file based system call"
select KEXEC_CORE
+ select HAVE_IMA_KEXEC
help
This is new version of kexec system call. This system call is
file based and takes file descriptors as system call argument
diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
index 361a1143e09e..66909505d959 100644
--- a/arch/arm64/kernel/machine_kexec_file.c
+++ b/arch/arm64/kernel/machine_kexec_file.c
@@ -21,6 +21,7 @@
#include <linux/string.h>
#include <linux/types.h>
#include <linux/vmalloc.h>
+#include <linux/ima.h>
#include <asm/byteorder.h>

/* relevant device tree properties */
@@ -62,6 +63,8 @@ static int setup_dtb(struct kimage *image,

off = ret;

+ ima_remove_kexec_buffer(dtb, ret);
+
ret = fdt_delprop(dtb, off, FDT_PROP_KEXEC_ELFHDR);
if (ret && ret != -FDT_ERR_NOTFOUND)
goto out;
@@ -136,6 +139,21 @@ static int setup_dtb(struct kimage *image,
FDT_PROP_KASLR_SEED);
}

+ /* add ima-kexec-buffer */
+ if (image->arch.ima_buffer_size > 0) {
+ ret = fdt_appendprop_addrrange(dtb, 0, off,
+ FDT_PROP_IMA_KEXEC_BUFFER,
+ image->arch.ima_buffer_addr,
+ image->arch.ima_buffer_size);
+ if (ret)
+ return (ret == -FDT_ERR_NOSPACE ? -ENOMEM : -EINVAL);
+
+ ret = fdt_add_mem_rsv(dtb, image->arch.ima_buffer_addr,
+ image->arch.ima_buffer_size);
+ if (ret)
+ goto out;
+ }
+
/* add rng-seed */
if (rng_is_initialized()) {
void *rng_seed;
--
2.28.0