Carry ima measurement log for arm64 via kexec_file_load

Carry ima measurement log for arm64 via kexec_file_load. add support to kexec_file_load to pass the ima measurement log

This patch adds entry for the ima measurement log in the

dtb which is then used in the kexec'ed session to fetch the segment and then load the ima measurement log.

Signed-off-by Prakhar Srivastava <[email protected]>

arch/arm64/Kconfig +0 -0

index 3adcec05b1f6..9e1b831e7baa 100644

arch/arm64/Kconfig +1 -0

+
 config KEXEC_VERIFY_SIG
        bool "Verify kernel signature during kexec_file_load() syscall"
        depends on KEXEC_FILE

arch/arm64/include/asm/ima.h new file +0 -0

new file mode 100644
index 000000000000..2c504281028d

arch/arm64/include/asm/ima.h new file +26 -0

+
+struct kimage;
+
+int ima_get_kexec_buffer(void **addr, size_t *size);
+int ima_free_kexec_buffer(void);
+
+#ifdef CONFIG_IMA
+void remove_ima_buffer(void *fdt, int chosen_node);
+#else
+static inline void remove_ima_buffer(void *fdt, int chosen_node) {}
+#endif
+
+#ifdef CONFIG_IMA_KEXEC
+int arch_ima_add_kexec_buffer(struct kimage *image, unsigned long load_addr,
+                             size_t size);
+
+int setup_ima_buffer(const struct kimage *image, void *fdt, int chosen_node);
+#else
+static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
+                                  int chosen_node)
+{
+       remove_ima_buffer(fdt, chosen_node);
+       return 0;
+}
+#endif /* CONFIG_IMA_KEXEC */
+#endif /* _ASM_ARM64_IMA_H */

arch/arm64/include/asm/kexec.h +0 -0

index 12a561a54128..ca1f9ad5c4d4 100644

arch/arm64/include/asm/kexec.h +2 -0

 };
 
 extern const struct kexec_file_ops kexec_image_ops;

@@ -107,6 +109,8 @@ extern int load_other_segments(struct kimage *image,
                unsigned long kernel_load_addr, unsigned long kernel_size,
                char *initrd, unsigned long initrd_len,
                char *cmdline);
+extern int delete_fdt_mem_rsv(void *fdt, unsigned long start,
+               unsigned long size);
 #endif
 
 #endif /* __ASSEMBLY__ */

arch/arm64/kernel/ima_kexec.c new file +0 -0

new file mode 100644
index 000000000000..5ae0d776ec42

arch/arm64/kernel/ima_kexec.c new file +134 -0

+ */
+
+#include <linux/slab.h>
+#include <linux/kexec.h>
+#include <linux/of.h>
+#include <linux/memblock.h>
+#include <linux/libfdt.h>
+#include <asm/kexec.h>
+#include <asm/ima.h>
+
+static int get_addr_size_cells(int *addr_cells, int *size_cells)
+{
+       struct device_node *root;
+
+       root = of_find_node_by_path("/");
+       if (!root)
+               return -EINVAL;
+
+       *addr_cells = of_n_addr_cells(root);
+       *size_cells = of_n_size_cells(root);
+
+       of_node_put(root);
+
+       return 0;
+}
+
+static int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
+                              size_t *size)
+{
+
+       int ret, addr_cells, size_cells;
+
+       ret = get_addr_size_cells(&addr_cells, &size_cells);
+       if (ret)
+               return ret;
+
+       if (len < 4 * (addr_cells + size_cells))
+               return -ENOENT;
+
+       *addr = of_read_number(prop, addr_cells);
+       *size = of_read_number(prop + 4 * addr_cells, size_cells);
+
+       return 0;
+}
+
+/**
+ * ima_get_kexec_buffer - get IMA buffer from the previous kernel
+ * @addr:      On successful return, set to point to the buffer contents.
+ * @size:      On successful return, set to the buffer size.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int ima_get_kexec_buffer(void **addr, size_t *size)
+{
+       int ret, len;
+       unsigned long tmp_addr;
+       size_t tmp_size;
+       const void *prop;
+
+       prop = of_get_property(of_chosen, FDT_PROP_KEXEC_BUFFER, &len);
+       if (!prop)
+               return -ENOENT;
+
+       ret = do_get_kexec_buffer(prop, len, &tmp_addr, &tmp_size);
+       if (ret)
+               return ret;
+
+       *addr = __va(tmp_addr);
+       *size = tmp_size;
+       return 0;
+}
+
+/**
+ * ima_free_kexec_buffer - free memory used by the IMA buffer
+ */
+int ima_free_kexec_buffer(void)
+{
+       int ret;
+       unsigned long addr;
+       size_t size;
+       struct property *prop;
+
+       prop = of_find_property(of_chosen, FDT_PROP_KEXEC_BUFFER, NULL);
+       if (!prop)
+               return -ENOENT;
+
+       ret = do_get_kexec_buffer(prop->value, prop->length, &addr, &size);
+       if (ret)
+               return ret;
+
+       ret = of_remove_property(of_chosen, prop);
+       if (ret)
+               return ret;
+
+       return memblock_free(addr, size);
+}
+
+#ifdef CONFIG_IMA
+/**
+ * remove_ima_buffer - remove the IMA buffer property and reservation from @fdt
+ *
+ * The IMA measurement buffer is of no use to a subsequent kernel, so we always
+ * remove it from the device tree.
+ */
+void remove_ima_buffer(void *fdt, int chosen_node)
+{
+       int ret, len;
+       unsigned long addr;
+       size_t size;
+       const void *prop;
+
+       prop = fdt_getprop(fdt, chosen_node, FDT_PROP_KEXEC_BUFFER, &len);
+       if (!prop)
+               return;
+
+       ret = do_get_kexec_buffer(prop, len, &addr, &size);
+       fdt_delprop(fdt, chosen_node, FDT_PROP_KEXEC_BUFFER);
+       if (ret)
+               return;
+
+       ret = delete_fdt_mem_rsv(fdt, addr, size);
+       if (!ret)
+               pr_debug("Removed old IMA buffer reservation.\n");
+}
+#endif /* CONFIG_IMA */
+
+#ifdef CONFIG_IMA_KEXEC
+/**
+ * arch_ima_add_kexec_buffer - do arch-specific steps to add the IMA buffer
+ *
+ * Architectures should use this function to pass on the IMA buffer
+ * information to the next kernel.
+ *
+ * Return: 0 on success, negative errno on error.

arch/arm64/kernel/ima_kexec.c new file +6 -0

+{
+       if (cells == 1) {
+               u32 tmp;
+
+               if (value > U32_MAX)
+                       return -EINVAL;

arch/arm64/kernel/ima_kexec.c new file +41 -0

+ *
+ * Return: 0 on success, or negative errno on error.
+ */
+int setup_ima_buffer(const struct kimage *image, void *dtb, int chosen_node)
+{
+       int ret, addr_cells, size_cells, entry_size;
+       u8 value[16];
+
+       remove_ima_buffer(dtb, chosen_node);
+
+       ret = get_addr_size_cells(&addr_cells, &size_cells);
+       if (ret)
+               return ret;
+
+       entry_size = 4 * (addr_cells + size_cells);
+
+       if (entry_size > sizeof(value))
+               return -EINVAL;
+
+       ret = write_number(value, image->arch.ima_buffer_addr, addr_cells);
+       if (ret)
+               return ret;
+
+       ret = write_number(value + 4 * addr_cells, image->arch.ima_buffer_size,
+                       size_cells);
+       if (ret)
+               return ret;
+
+       ret = fdt_setprop(dtb, chosen_node, FDT_PROP_KEXEC_BUFFER, value,
+                         entry_size);
+       if (ret < 0)
+               return -EINVAL;
+
+       ret = fdt_add_mem_rsv(dtb, image->segment[0].mem,
+                             image->segment[0].memsz);
+       if (ret)
+               return -EINVAL;
+
+       return 0;
+}
+#endif /* CONFIG_IMA_KEXEC */

arch/arm64/kernel/machine_kexec_file.c +6 -0

index 58871333737a..c05ad6b74b62 100644
@@ -21,6 +21,7 @@
 #include <linux/types.h>
 #include <linux/vmalloc.h>
 #include <asm/byteorder.h>
+#include <asm/ima.h>
 
 /* relevant device tree properties */
 #define FDT_PROP_INITRD_START  "linux,initrd-start"

@@ -85,6 +86,11 @@ static int setup_dtb(struct kimage *image,
                        goto out;
        }
 
+       /* add ima_buffer */
+       ret = setup_ima_buffer(image, dtb, off);
+       if (ret)
+               goto out;
+
        /* add kaslr-seed */
        ret = fdt_delprop(dtb, off, FDT_PROP_KASLR_SEED);
        if  (ret == -FDT_ERR_NOTFOUND)

A lot of this code looks DT generic. Can it be moved out of the arch layer to drivers/of/?

The code is in most part same as powerpc, i want to get feedback as to how/correct way to refactor the code so that cross architecture partial helpers can be put in a common place.

Carry ima measurement log for arm64 via kexec_file_load. add support to kexec_file_load to pass the ima measurement log

This patch adds entry for the ima measurement log in the dtb which is then used in the kexec'ed session to fetch the segment and then load the ima measurement log.

Signed-off-by Prakhar Srivastava <[email protected]>

---
 arch/arm64/Kconfig                     |   7 +
 arch/arm64/include/asm/ima.h           |  31 ++++
 arch/arm64/include/asm/kexec.h         |   4 +
 arch/arm64/kernel/Makefile             |   1 +
 arch/arm64/kernel/ima_kexec.c          | 219 +++++++++++++++++++++++++
 arch/arm64/kernel/machine_kexec_file.c |  39 +++++
 6 files changed, 301 insertions(+)
 create mode 100644 arch/arm64/include/asm/ima.h
 create mode 100644 arch/arm64/kernel/ima_kexec.c

arch/arm64/Kconfig +0 -0

index 3adcec05b1f6..9e1b831e7baa 100644
@@ -964,6 +964,13 @@ config KEXEC_FILE
 	  for kernel and initramfs as opposed to list of segments as
 	  accepted by previous system call.
 

arch/arm64/kernel/Makefile +1 -0

index 478491f07b4f..9620f90bd0e1 100644
@@ -63,6 +63,7 @@ obj-$(CONFIG_CRASH_CORE)		+= crash_core.o
 obj-$(CONFIG_ARM_SDE_INTERFACE)		+= sdei.o
 obj-$(CONFIG_ARM64_SSBD)		+= ssbd.o
 obj-$(CONFIG_ARM64_PTR_AUTH)		+= pointer_auth.o
+obj-$(CONFIG_HAVE_IMA_KEXEC)		+= ima_kexec.o
 
 obj-y					+= vdso/ probes/
 obj-$(CONFIG_COMPAT_VDSO)		+= vdso32/

arch/arm64/kernel/ima_kexec.c new file +1 -0

new file mode 100644
index 000000000000..5ae0d776ec42
@@ -0,0 +1,219 @@
+/*

arch/arm64/kernel/ima_kexec.c new file +18 -0

+#include <linux/slab.h>
+#include <linux/kexec.h>
+#include <linux/of.h>
+#include <linux/memblock.h>
+#include <linux/libfdt.h>
+#include <asm/kexec.h>
+#include <asm/ima.h>
+
+static int get_addr_size_cells(int *addr_cells, int *size_cells)
+{
+	struct device_node *root;
+
+	root = of_find_node_by_path("/");
+	if (!root)
+		return -EINVAL;
+
+	*addr_cells = of_n_addr_cells(root);
+	*size_cells = of_n_size_cells(root);

arch/arm64/kernel/ima_kexec.c new file +55 -0

+	int ret, addr_cells, size_cells;
+
+	ret = get_addr_size_cells(&addr_cells, &size_cells);
+	if (ret)
+		return ret;
+
+	if (len < 4 * (addr_cells + size_cells))
+		return -ENOENT;
+
+	*addr = of_read_number(prop, addr_cells);
+	*size = of_read_number(prop + 4 * addr_cells, size_cells);
+
+	return 0;
+}
+
+/**
+ * ima_get_kexec_buffer - get IMA buffer from the previous kernel
+ * @addr:	On successful return, set to point to the buffer contents.
+ * @size:	On successful return, set to the buffer size.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int ima_get_kexec_buffer(void **addr, size_t *size)
+{
+	int ret, len;
+	unsigned long tmp_addr;
+	size_t tmp_size;
+	const void *prop;
+
+	prop = of_get_property(of_chosen, FDT_PROP_KEXEC_BUFFER, &len);
+	if (!prop)
+		return -ENOENT;
+
+	ret = do_get_kexec_buffer(prop, len, &tmp_addr, &tmp_size);
+	if (ret)
+		return ret;
+
+	*addr = __va(tmp_addr);
+	*size = tmp_size;
+	return 0;
+}
+
+/**
+ * ima_free_kexec_buffer - free memory used by the IMA buffer
+ */
+int ima_free_kexec_buffer(void)
+{
+	int ret;
+	unsigned long addr;
+	size_t size;
+	struct property *prop;
+
+	prop = of_find_property(of_chosen, FDT_PROP_KEXEC_BUFFER, NULL);
+	if (!prop)
+		return -ENOENT;

arch/arm64/kernel/ima_kexec.c new file +65 -0

+/**
+ * remove_ima_buffer - remove the IMA buffer property and reservation from @fdt
+ *
+ * The IMA measurement buffer is of no use to a subsequent kernel, so we always
+ * remove it from the device tree.
+ */
+void remove_ima_buffer(void *fdt, int chosen_node)
+{
+	int ret, len;
+	unsigned long addr;
+	size_t size;
+	const void *prop;
+
+	prop = fdt_getprop(fdt, chosen_node, FDT_PROP_KEXEC_BUFFER, &len);
+	if (!prop)
+		return;
+
+	ret = do_get_kexec_buffer(prop, len, &addr, &size);
+	fdt_delprop(fdt, chosen_node, FDT_PROP_KEXEC_BUFFER);
+	if (ret)
+		return;
+
+	ret = delete_fdt_mem_rsv(fdt, addr, size);
+	if (!ret)
+		pr_debug("Removed old IMA buffer reservation.\n");
+}
+#endif /* CONFIG_IMA */
+
+#ifdef CONFIG_IMA_KEXEC
+/**
+ * arch_ima_add_kexec_buffer - do arch-specific steps to add the IMA buffer
+ *
+ * Architectures should use this function to pass on the IMA buffer
+ * information to the next kernel.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int arch_ima_add_kexec_buffer(struct kimage *image, unsigned long load_addr,
+			      size_t size)
+{
+	image->arch.ima_buffer_addr = load_addr;
+	image->arch.ima_buffer_size = size;
+	return 0;
+}
+
+static int write_number(void *p, u64 value, int cells)
+{
+	if (cells == 1) {
+		u32 tmp;
+
+		if (value > U32_MAX)
+			return -EINVAL;
+
+		tmp = cpu_to_be32(value);
+		memcpy(p, &tmp, sizeof(tmp));
+	} else if (cells == 2) {
+		u64 tmp;
+
+		tmp = cpu_to_be64(value);
+		memcpy(p, &tmp, sizeof(tmp));
+	} else
+		return -EINVAL;
+	return 0;
+}
+

arch/arm64/kernel/ima_kexec.c new file +16 -0

+
+	ret = get_addr_size_cells(&addr_cells, &size_cells);
+	if (ret)
+		return ret;
+
+	entry_size = 4 * (addr_cells + size_cells);
+
+	if (entry_size > sizeof(value))
+		return -EINVAL;
+
+	ret = write_number(value, image->arch.ima_buffer_addr, addr_cells);
+	if (ret)
+		return ret;
+
+	ret = write_number(value + 4 * addr_cells, image->arch.ima_buffer_size,
+			size_cells);

arch/arm64/kernel/ima_kexec.c new file +6 -0

+	if (ret)
+		return -EINVAL;
+
+	return 0;
+}
+#endif /* CONFIG_IMA_KEXEC */

arch/arm64/kernel/machine_kexec_file.c +28 -0

index 58871333737a..c05ad6b74b62 100644
@@ -21,6 +21,7 @@
 #include <linux/types.h>
 #include <linux/vmalloc.h>
 #include <asm/byteorder.h>
+#include <asm/ima.h>
 
 /* relevant device tree properties */
 #define FDT_PROP_INITRD_START	"linux,initrd-start"

@@ -85,6 +86,11 @@ static int setup_dtb(struct kimage *image,
 			goto out;
 	}
 
+	/* add ima_buffer */
+	ret = setup_ima_buffer(image, dtb, off);
+	if (ret)
+		goto out;
+
 	/* add kaslr-seed */
 	ret = fdt_delprop(dtb, off, FDT_PROP_KASLR_SEED);
 	if  (ret == -FDT_ERR_NOTFOUND)

@@ -114,6 +120,39 @@ static int setup_dtb(struct kimage *image,
  */
 #define DTB_EXTRA_SPACE 0x1000
 
+
+/**
+ * delete_fdt_mem_rsv - delete memory reservation with given address and size
+ *
+ * Return: 0 on success, or negative errno on error.
+ */
+int delete_fdt_mem_rsv(void *fdt, unsigned long start, unsigned long size)
+{
+	int i, ret, num_rsvs = fdt_num_mem_rsv(fdt);
+
+	for (i = 0; i < num_rsvs; i++) {
+		uint64_t rsv_start, rsv_size;
+
+		ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size);
+		if (ret) {
+			pr_err("Malformed device tree.\n");
+			return -EINVAL;
+		}
+
+		if (rsv_start == start && rsv_size == size) {
+			ret = fdt_del_mem_rsv(fdt, i);
+			if (ret) {

Hello Prakhar,

Answering this part from the cover letter:

Quoted 3 lines

The code is in most part same as powerpc, i want to get feedback as to how/correct way to refactor the code so that cross architecture partial helpers can be put in a common place.

That's a great idea. If it could go to drivers/of/ as Stephen Boyd mentioned in the other email that would be great.

More comments below.
-Addressed those in the v1 patch
Prakhar Srivastava <[email protected]> writes:

Quoted 7 lines · Thiago Jung Bauermann

Hello Prakhar,

Answering this part from the cover letter:

Quoted 3 lines

The code is in most part same as powerpc, i want to get feedback as to how/correct way to refactor the code so that cross architecture partial helpers can be put in a common place.

I started refactoring code to bring helpers under drivers/of, but

i soon reliazed the current implementation can be changed a bit

so that some of the additional functions can be sourced from

existing fdt_*/of_* functions since the fdt_ima was seeming to be

an overkill. I have done so in the V1 patch and also addressed

comments you have.

Hopefully its(v1) is a cleaner approach.

- Thanks for the review, and guidance.

Quoted 7 lines

That's a great idea. If it could go to drivers/of/ as Stephen Boyd mentioned in the other email that would be great.

More comments below.
-Addressed those in the v1 patch
Prakhar Srivastava <[email protected]> writes:

Hi Prakhar,
"Carrying over the ima log during kexec_file_load" was originally posted on 5/10 and 5/31 without a cover letter. On 8/29 it was reposted as an RFC with a cover letter.  The cover letter was v1, but the patch itself was not.  In the future, please use the "git format- patch "-subject-prefix" option to add the version number to both the cover letter and the patches.

The comments you received were based on the 8/29 version.  I haven't seen anything after that.

Mimi