[v1 PATCH 1/2] Refactoring carrying over IMA measuremnet logs over Kexec.

From: Prakhar Srivastava
Date: Sun Jun 07 2020 - 19:33:50 EST


This patch moves the non-architecture specific code out of powerpc and
adds to security/ima.
Update the arm64 and powerpc kexec file load paths to carry the IMA measurement
logs.

Signed-off-by: Prakhar Srivastava <prsriva@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/ima.h | 24 ++++
arch/arm64/include/asm/kexec.h | 3 +
arch/arm64/kernel/machine_kexec_file.c | 47 ++++++--
arch/powerpc/include/asm/ima.h | 9 --
arch/powerpc/kexec/ima.c | 117 +------------------
security/integrity/ima/ima_kexec.c | 151 +++++++++++++++++++++++++
7 files changed, 219 insertions(+), 133 deletions(-)
create mode 100644 arch/arm64/include/asm/ima.h

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 5d513f461957..3d544e2e25e6 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1070,6 +1070,7 @@ 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/include/asm/ima.h b/arch/arm64/include/asm/ima.h
new file mode 100644
index 000000000000..8946bae8baa2
--- /dev/null
+++ b/arch/arm64/include/asm/ima.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_ARCH_IMA_H
+#define _ASM_ARCH_IMA_H
+
+struct kimage;
+
+#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 arch_ima_add_kexec_buffer(struct kimage *image,
+ unsigned long load_addr, size_t size)
+{
+ return 0;
+}
+static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
+ int chosen_node)
+{
+ return 0;
+}
+#endif /* CONFIG_IMA_KEXEC */
+#endif /* _ASM_ARCH_IMA_H */
diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
index d24b527e8c00..7bd60c185ad3 100644
--- a/arch/arm64/include/asm/kexec.h
+++ b/arch/arm64/include/asm/kexec.h
@@ -100,6 +100,9 @@ struct kimage_arch {
void *elf_headers;
unsigned long elf_headers_mem;
unsigned long elf_headers_sz;
+
+ phys_addr_t ima_buffer_addr;
+ size_t ima_buffer_size;
};

extern const struct kexec_file_ops kexec_image_ops;
diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
index b40c3b0def92..1e9007c926db 100644
--- a/arch/arm64/kernel/machine_kexec_file.c
+++ b/arch/arm64/kernel/machine_kexec_file.c
@@ -24,20 +24,37 @@
#include <asm/byteorder.h>

/* relevant device tree properties */
-#define FDT_PROP_KEXEC_ELFHDR "linux,elfcorehdr"
-#define FDT_PROP_MEM_RANGE "linux,usable-memory-range"
-#define FDT_PROP_INITRD_START "linux,initrd-start"
-#define FDT_PROP_INITRD_END "linux,initrd-end"
-#define FDT_PROP_BOOTARGS "bootargs"
-#define FDT_PROP_KASLR_SEED "kaslr-seed"
-#define FDT_PROP_RNG_SEED "rng-seed"
-#define RNG_SEED_SIZE 128
+#define FDT_PROP_KEXEC_ELFHDR "linux,elfcorehdr"
+#define FDT_PROP_MEM_RANGE "linux,usable-memory-range"
+#define FDT_PROP_INITRD_START "linux,initrd-start"
+#define FDT_PROP_INITRD_END "linux,initrd-end"
+#define FDT_PROP_BOOTARGS "bootargs"
+#define FDT_PROP_KASLR_SEED "kaslr-seed"
+#define FDT_PROP_RNG_SEED "rng-seed"
+#define FDT_PROP_IMA_KEXEC_BUFFER "linux,ima-kexec-buffer"
+#define RNG_SEED_SIZE 128

const struct kexec_file_ops * const kexec_file_loaders[] = {
&kexec_image_ops,
NULL
};

+/**
+ * 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;
+}
+
int arch_kimage_file_post_load_cleanup(struct kimage *image)
{
vfree(image->arch.dtb);
@@ -66,6 +83,9 @@ static int setup_dtb(struct kimage *image,
if (ret && ret != -FDT_ERR_NOTFOUND)
goto out;
ret = fdt_delprop(dtb, off, FDT_PROP_MEM_RANGE);
+ if (ret && ret != -FDT_ERR_NOTFOUND)
+ goto out;
+ ret = fdt_delprop(dtb, off, FDT_PROP_IMA_KEXEC_BUFFER);
if (ret && ret != -FDT_ERR_NOTFOUND)
goto out;

@@ -119,6 +139,17 @@ static int setup_dtb(struct kimage *image,
goto out;
}

+ 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);
+
+ }
+
/* add kaslr-seed */
ret = fdt_delprop(dtb, off, FDT_PROP_KASLR_SEED);
if (ret == -FDT_ERR_NOTFOUND)
diff --git a/arch/powerpc/include/asm/ima.h b/arch/powerpc/include/asm/ima.h
index ead488cf3981..80b83881fa03 100644
--- a/arch/powerpc/include/asm/ima.h
+++ b/arch/powerpc/include/asm/ima.h
@@ -4,15 +4,6 @@

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);
diff --git a/arch/powerpc/kexec/ima.c b/arch/powerpc/kexec/ima.c
index 720e50e490b6..537e4f82a050 100644
--- a/arch/powerpc/kexec/ima.c
+++ b/arch/powerpc/kexec/ima.c
@@ -12,121 +12,6 @@
#include <linux/memblock.h>
#include <linux/libfdt.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, "linux,ima-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, "linux,ima-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);
-
-}
-
-/**
- * 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, "linux,ima-kexec-buffer", &len);
- if (!prop)
- return;
-
- ret = do_get_kexec_buffer(prop, len, &addr, &size);
- fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer");
- if (ret)
- return;
-
- ret = delete_fdt_mem_rsv(fdt, addr, size);
- if (!ret)
- pr_debug("Removed old IMA buffer reservation.\n");
-}
-
#ifdef CONFIG_IMA_KEXEC
/**
* arch_ima_add_kexec_buffer - do arch-specific steps to add the IMA buffer
@@ -179,7 +64,7 @@ int setup_ima_buffer(const struct kimage *image, void *fdt, int chosen_node)
int ret, addr_cells, size_cells, entry_size;
u8 value[16];

- remove_ima_buffer(fdt, chosen_node);
+// remove_ima_buffer(fdt, chosen_node);
if (!image->arch.ima_buffer_size)
return 0;

diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index 121de3e04af2..36887ed4ff82 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -10,8 +10,159 @@
#include <linux/seq_file.h>
#include <linux/vmalloc.h>
#include <linux/kexec.h>
+#include <linux/of.h>
+#include <linux/memblock.h>
+#include <linux/libfdt.h>
#include "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, "linux,ima-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;
+}
+
+/**
+ * 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) {
+ pr_err("Error deleting device tree reservation.\n");
+ return -EINVAL;
+ }
+
+ return 0;
+ }
+ }
+
+ return -ENOENT;
+}
+
+/**
+ * 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, "linux,ima-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);
+
+}
+
+/**
+ * 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, "linux,ima-kexec-buffer", &len);
+ if (!prop)
+ return;
+
+ ret = do_get_kexec_buffer(prop, len, &addr, &size);
+ fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer");
+ if (ret)
+ return;
+
+ ret = delete_fdt_mem_rsv(fdt, addr, size);
+ if (!ret)
+ pr_debug("Removed old IMA buffer reservation.\n");
+}
+
+
#ifdef CONFIG_IMA_KEXEC
static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
unsigned long segment_size)
--
2.25.1