[PATCH v6 0/3] Carry forward IMA measurement log on kexec on ARM64

[PATCH v6 0/3] Carry forward IMA measurement log on kexec on ARM64

[Lakshmi Ramasubramanian]

On kexec file load Integrity Measurement Architecture(IMA) subsystem
may verify the IMA signature of the kernel and initramfs, and measure
it. The command line parameters passed to the kernel in the kexec call
may also be measured by IMA. A remote attestation service can verify
the measurement through the IMA log and the TPM PCR data. This can be
achieved only if the IMA measurement log is carried over from
the current kernel to the next kernel across the kexec call.
However in the current implementation the IMA measurement logs are not
carried over on ARM64 platforms. Therefore a remote attestation service
cannot verify the authenticity of the running kernel on ARM64 platforms
when the kernel is updated through the kexec system call.

This patch series adds support for carrying forward the IMA measurement
log on kexec on ARM64. powerpc already supports carrying forward
the IMA measurement log on kexec.

This series refactors the platform independent code defined for powerpc
such that it can be reused for ARM64 as well. A chosen node namely
"linux,ima-kexec-buffer" is added to the DTB for ARM64 to hold
the address and the size of the memory reserved to carry
the IMA measurement log.

This patch series has been tested for ARM64 platform using QEMU.
I would like help from the community for testing this change on powerpc.
Thanks.

This series is based on commit f4d51dffc6c0 ("Linux 5.9-rc4") in
https://github.com/torvalds/linux "master" branch.

Changelog:

v6:
  - Remove any existing FDT_PROP_IMA_KEXEC_BUFFER property in the device
    tree and also its corresponding memory reservation in the currently
    running kernel.
  - Moved the function remove_ima_buffer() defined for powerpc to IMA
    and renamed the function to ima_remove_kexec_buffer(). Also, moved
    delete_fdt_mem_rsv() from powerpc to IMA.

v5:
  - Merged get_addr_size_cells() and do_get_kexec_buffer() into a single
    function when moving the arch independent code from powerpc to IMA
  - Reverted the change to use FDT functions in powerpc code and added
    back the original code in get_addr_size_cells() and
    do_get_kexec_buffer() for powerpc.
  - Added fdt_add_mem_rsv() for ARM64 to reserve the memory for
    the IMA log buffer during kexec.
  - Fixed the warning reported by kernel test bot for ARM64
    arch_ima_add_kexec_buffer() - moved this function to a new file
    namely arch/arm64/kernel/ima_kexec.c

v4:
  - Submitting the patch series on behalf of the original author
    Prakhar Srivastava <prsriva@linux.microsoft.com>
  - Moved FDT_PROP_IMA_KEXEC_BUFFER ("linux,ima-kexec-buffer") to
    libfdt.h so that it can be shared by multiple platforms.

v3:
Breakup patches further into separate patches.
  - Refactoring non architecture specific code out of powerpc
  - Update powerpc related code to use fdt functions
  - Update IMA buffer read related code to use of functions
  - Add support to store the memory information of the IMA
    measurement logs to be carried forward.
  - Update the property strings to align with documented nodes
    https://github.com/devicetree-org/dt-schema/pull/46

v2:
  Break patches into separate patches.
  - Powerpc related Refactoring
  - Updating the docuemntation for chosen node
  - Updating arm64 to support IMA buffer pass

v1:
  Refactoring carrying over IMA measuremnet logs over Kexec. This patch
    moves the non-architecture specific code out of powerpc and adds to
    security/ima.(Suggested by Thiago)
  Add Documentation regarding the ima-kexec-buffer node in the chosen
    node documentation

v0:
  Add a layer of abstraction to use the memory reserved by device tree
    for ima buffer pass.
  Add support for ima buffer pass using reserved memory for arm64 kexec.
    Update the arch sepcific code path in kexec file load to store the
    ima buffer in the reserved memory. The same reserved memory is read
    on kexec or cold boot.

Lakshmi Ramasubramanian (3):
  powerpc: Refactor kexec functions to move arch independent code to IMA
  arm64: Store IMA log information in kimage used for kexec
  arm64: Add IMA kexec buffer to DTB

 arch/arm64/Kconfig                      |   1 +
 arch/arm64/include/asm/ima.h            |  18 ++++
 arch/arm64/include/asm/kexec.h          |   3 +
 arch/arm64/kernel/Makefile              |   1 +
 arch/arm64/kernel/ima_kexec.c           |  34 ++++++++
 arch/arm64/kernel/machine_kexec_file.c  |  18 ++++
 arch/powerpc/include/asm/ima.h          |  11 +--
 arch/powerpc/include/asm/kexec.h        |   1 -
 arch/powerpc/kexec/file_load.c          |  33 +-------
 arch/powerpc/kexec/ima.c                | 104 +-----------------------
 include/linux/ima.h                     |   2 +
 include/linux/kexec.h                   |  11 +++
 include/linux/libfdt.h                  |   3 +
 security/integrity/ima/Makefile         |   3 +-
 security/integrity/ima/ima.h            |   2 +
 security/integrity/ima/ima_fdt.c        |  80 ++++++++++++++++++
 security/integrity/ima/ima_kexec.c      |  58 +++++++++++++
 security/integrity/ima/ima_kexec_file.c |  51 ++++++++++++
 18 files changed, 289 insertions(+), 145 deletions(-)
 create mode 100644 arch/arm64/include/asm/ima.h
 create mode 100644 arch/arm64/kernel/ima_kexec.c
 create mode 100644 security/integrity/ima/ima_fdt.c
 create mode 100644 security/integrity/ima/ima_kexec_file.c

-- 
2.28.0

[PATCH v6 1/3] powerpc: Refactor kexec functions to move arch independent code to IMA

[Lakshmi Ramasubramanian]

The functions ima_get_kexec_buffer(), ima_free_kexec_buffer(),
remove_ima_buffer(), and delete_fdt_mem_rsv() that handle carrying
forward the IMA measurement logs on kexec for powerpc do not have
architecture specific code, but they are currently defined for
powerpc only.

Move these functions to IMA subsystem so that it can be used for other
architectures as well. A later patch in this series will use these
functions for carrying forward the IMA measurement log for ARM64.
Rename remove_ima_buffer() to ima_remove_kexec_buffer().

Define FDT_PROP_IMA_KEXEC_BUFFER for the chosen node, namely
"linux,ima-kexec-buffer", that is added to the DTB to hold
the address and the size of the memory reserved to carry
the IMA measurement log.

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/powerpc/include/asm/ima.h          |  11 +--
 arch/powerpc/include/asm/kexec.h        |   1 -
 arch/powerpc/kexec/file_load.c          |  33 +-------
 arch/powerpc/kexec/ima.c                | 104 +-----------------------
 include/linux/ima.h                     |   2 +
 include/linux/kexec.h                   |  11 +++
 include/linux/libfdt.h                  |   3 +
 security/integrity/ima/Makefile         |   3 +-
 security/integrity/ima/ima.h            |   2 +
 security/integrity/ima/ima_fdt.c        |  80 ++++++++++++++++++
 security/integrity/ima/ima_kexec.c      |  58 +++++++++++++
 security/integrity/ima/ima_kexec_file.c |  51 ++++++++++++
 12 files changed, 214 insertions(+), 145 deletions(-)
 create mode 100644 security/integrity/ima/ima_fdt.c
 create mode 100644 security/integrity/ima/ima_kexec_file.c

diff --git a/arch/powerpc/include/asm/ima.h b/arch/powerpc/include/asm/ima.h
index ead488cf3981..188146ecbfaf 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);
@@ -22,7 +13,7 @@ int setup_ima_buffer(const struct kimage *image, void *fdt, int chosen_node);
 static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
 				   int chosen_node)
 {
-	remove_ima_buffer(fdt, chosen_node);
+	ima_remove_kexec_buffer(fdt, chosen_node);
 	return 0;
 }
 #endif /* CONFIG_IMA_KEXEC */
diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
index 55d6ede30c19..7c223031ecdd 100644
--- a/arch/powerpc/include/asm/kexec.h
+++ b/arch/powerpc/include/asm/kexec.h
@@ -126,7 +126,6 @@ int setup_purgatory(struct kimage *image, const void *slave_code,
 int setup_new_fdt(const struct kimage *image, void *fdt,
 		  unsigned long initrd_load_addr, unsigned long initrd_len,
 		  const char *cmdline);
-int delete_fdt_mem_rsv(void *fdt, unsigned long start, unsigned long size);
 
 #ifdef CONFIG_PPC64
 struct kexec_buf;
diff --git a/arch/powerpc/kexec/file_load.c b/arch/powerpc/kexec/file_load.c
index 9a232bc36c8f..7a17655c530e 100644
--- a/arch/powerpc/kexec/file_load.c
+++ b/arch/powerpc/kexec/file_load.c
@@ -18,6 +18,7 @@
 #include <linux/kexec.h>
 #include <linux/of_fdt.h>
 #include <linux/libfdt.h>
+#include <linux/kexec.h>
 #include <asm/setup.h>
 #include <asm/ima.h>
 
@@ -109,38 +110,6 @@ int setup_purgatory(struct kimage *image, const void *slave_code,
 	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;
-}
-
 /*
  * setup_new_fdt - modify /chosen and memory reservation for the next kernel
  * @image:		kexec image being loaded.
diff --git a/arch/powerpc/kexec/ima.c b/arch/powerpc/kexec/ima.c
index 720e50e490b6..467647886064 100644
--- a/arch/powerpc/kexec/ima.c
+++ b/arch/powerpc/kexec/ima.c
@@ -9,6 +9,7 @@
 #include <linux/slab.h>
 #include <linux/kexec.h>
 #include <linux/of.h>
+#include <linux/ima.h>
 #include <linux/memblock.h>
 #include <linux/libfdt.h>
 
@@ -28,105 +29,6 @@ static int get_addr_size_cells(int *addr_cells, int *size_cells)
 	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 +81,7 @@ 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);
+	ima_remove_kexec_buffer(fdt, chosen_node);
 	if (!image->arch.ima_buffer_size)
 		return 0;
 
@@ -201,7 +103,7 @@ int setup_ima_buffer(const struct kimage *image, void *fdt, int chosen_node)
 	if (ret)
 		return ret;
 
-	ret = fdt_setprop(fdt, chosen_node, "linux,ima-kexec-buffer", value,
+	ret = fdt_setprop(fdt, chosen_node, FDT_PROP_IMA_KEXEC_BUFFER, value,
 			  entry_size);
 	if (ret < 0)
 		return -EINVAL;
diff --git a/include/linux/ima.h b/include/linux/ima.h
index d15100de6cdd..e8e0afdfe783 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -26,6 +26,7 @@ extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
 extern void ima_post_path_mknod(struct dentry *dentry);
 extern int ima_file_hash(struct file *file, char *buf, size_t buf_size);
 extern void ima_kexec_cmdline(int kernel_fd, const void *buf, int size);
+extern void ima_remove_kexec_buffer(void *fdt, int chosen_node);
 
 #ifdef CONFIG_IMA_KEXEC
 extern void ima_add_kexec_buffer(struct kimage *image);
@@ -104,6 +105,7 @@ static inline int ima_file_hash(struct file *file, char *buf, size_t buf_size)
 }
 
 static inline void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) {}
+static inline void ima_remove_kexec_buffer(void *fdt, int chosen_node) {}
 #endif /* CONFIG_IMA */
 
 #ifndef CONFIG_IMA_KEXEC
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 9e93bef52968..00a60dcc7075 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -223,8 +223,19 @@ extern int crash_exclude_mem_range(struct crash_mem *mem,
 				   unsigned long long mend);
 extern int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
 				       void **addr, unsigned long *sz);
+
+extern int delete_fdt_mem_rsv(void *fdt, unsigned long start,
+			      unsigned long size);
 #endif /* CONFIG_KEXEC_FILE */
 
+#ifndef CONFIG_KEXEC_FILE
+static inline int delete_fdt_mem_rsv(void *fdt, unsigned long start,
+				     unsigned long size)
+{
+	return 0;
+}
+#endif /* ifndef CONFIG_KEXEC_FILE */
+
 #ifdef CONFIG_KEXEC_ELF
 struct kexec_elf_info {
 	/*
diff --git a/include/linux/libfdt.h b/include/linux/libfdt.h
index 90ed4ebfa692..75fb40aa013b 100644
--- a/include/linux/libfdt.h
+++ b/include/linux/libfdt.h
@@ -5,4 +5,7 @@
 #include <linux/libfdt_env.h>
 #include "../../scripts/dtc/libfdt/libfdt.h"
 
+/* Common device tree properties */
+#define FDT_PROP_IMA_KEXEC_BUFFER	"linux,ima-kexec-buffer"
+
 #endif /* _INCLUDE_LIBFDT_H_ */
diff --git a/security/integrity/ima/Makefile b/security/integrity/ima/Makefile
index 67dabca670e2..05719fd28aec 100644
--- a/security/integrity/ima/Makefile
+++ b/security/integrity/ima/Makefile
@@ -7,10 +7,11 @@
 obj-$(CONFIG_IMA) += ima.o
 
 ima-y := ima_fs.o ima_queue.o ima_init.o ima_main.o ima_crypto.o ima_api.o \
-	 ima_policy.o ima_template.o ima_template_lib.o
+	 ima_policy.o ima_template.o ima_template_lib.o ima_fdt.o
 ima-$(CONFIG_IMA_APPRAISE) += ima_appraise.o
 ima-$(CONFIG_IMA_APPRAISE_MODSIG) += ima_modsig.o
 ima-$(CONFIG_HAVE_IMA_KEXEC) += ima_kexec.o
 ima-$(CONFIG_IMA_BLACKLIST_KEYRING) += ima_mok.o
 ima-$(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) += ima_asymmetric_keys.o
 ima-$(CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS) += ima_queue_keys.o
+ima-$(CONFIG_KEXEC_FILE) += ima_kexec_file.o
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 38043074ce5e..0d2bfe53be69 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -167,6 +167,8 @@ void ima_init_template_list(void);
 int __init ima_init_digests(void);
 int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event,
 			  void *lsm_data);
+int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
+			size_t *size);
 
 /*
  * used to protect h_table and sha_table
diff --git a/security/integrity/ima/ima_fdt.c b/security/integrity/ima/ima_fdt.c
new file mode 100644
index 000000000000..8c4cb580b772
--- /dev/null
+++ b/security/integrity/ima/ima_fdt.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2020 Microsoft Corporation
+ *
+ * Author: Lakshmi Ramasubramanian (nramas@linux.microsoft.com)
+ *
+ * ima_fdt.c
+ *	Implements functions to handle IMA buffer in device tree
+ */
+
+#include <linux/libfdt.h>
+#include <linux/kexec.h>
+#include <linux/ima.h>
+#include "ima.h"
+
+/**
+ * do_get_kexec_buffer - Get address and size of IMA kexec buffer
+ *
+ * @prop: IMA kexec buffer node in the device tree
+ * @addr: Return address of the node
+ * @size: Return size of the node
+ */
+int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
+			size_t *size)
+{
+	int addr_cells, 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);
+
+	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_remove_kexec_buffer - remove the IMA buffer property and
+ *			     reservation from @fdt
+ *
+ * @fdt: Flattened Device Tree to update
+ * @chosen_node: Offset to the chosen node in the device tree
+ *
+ * The IMA measurement buffer is of no use to a subsequent kernel,
+ * so we always remove it from the device tree.
+ */
+void ima_remove_kexec_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_IMA_KEXEC_BUFFER, &len);
+	if (!prop) {
+		pr_err("Unable to find the ima kexec buffer node\n");
+		return;
+	}
+
+	ret = do_get_kexec_buffer(prop, len, &addr, &size);
+	fdt_delprop(fdt, chosen_node, FDT_PROP_IMA_KEXEC_BUFFER);
+	if (ret) {
+		pr_err("Unable to delete the ima kexec buffer node\n");
+		return;
+	}
+
+	ret = delete_fdt_mem_rsv(fdt, addr, size);
+	if (!ret)
+		pr_err("Removed old IMA buffer reservation.\n");
+}
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index 121de3e04af2..ed70f99aeedc 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -10,8 +10,66 @@
 #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 <linux/ima.h>
 #include "ima.h"
 
+/**
+ * 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.
+ */
+static 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_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
+ */
+static 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_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);
+
+}
+
 #ifdef CONFIG_IMA_KEXEC
 static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
 				     unsigned long segment_size)
diff --git a/security/integrity/ima/ima_kexec_file.c b/security/integrity/ima/ima_kexec_file.c
new file mode 100644
index 000000000000..225e913e6ef2
--- /dev/null
+++ b/security/integrity/ima/ima_kexec_file.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2020 Microsoft Corporation
+ *
+ * Author: Lakshmi Ramasubramanian (nramas@linux.microsoft.com)
+ *
+ * ima_kexec_file.c
+ *	Implements functions to handle device tree operations
+ */
+
+#include <linux/libfdt.h>
+#include <linux/kexec.h>
+#include <linux/types.h>
+
+/**
+ * delete_fdt_mem_rsv - delete memory reservation with given address and size
+ *
+ * @fdt: Flattened Device Tree to update
+ * @start: Starting address of the property to update
+ * @size: Size of the buffer corresponding to the given property
+ *
+ * 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;
+			}
+
+			pr_err("Freed the reserved memory at %lu of size %lu\n",
+				start, size);
+			return 0;
+		}
+	}
+
+	return -ENOENT;
+}
-- 
2.28.0

[PATCH v6 2/3] arm64: Store IMA log information in kimage used for kexec

[Lakshmi Ramasubramanian]

Address and size of the buffer containing the IMA measurement log need
to be passed from the current kernel to the next kernel on kexec.

Add address and size fields to "struct kimage_arch" for ARM64 platform
to hold the address and size of the IMA measurement log buffer.
Define an architecture specific function for ARM64 namely
arch_ima_add_kexec_buffer() that will set the address and size of
the current kernel's IMA buffer to be passed to the next kernel on kexec.

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>
Reported-by: kernel test robot <lkp@intel.com> warning: no previous prototype for 'arch_ima_add_kexec_buffer' [-Wmissing-prototypes]
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
---
 arch/arm64/include/asm/ima.h   | 18 ++++++++++++++++++
 arch/arm64/include/asm/kexec.h |  3 +++
 arch/arm64/kernel/Makefile     |  1 +
 arch/arm64/kernel/ima_kexec.c  | 34 ++++++++++++++++++++++++++++++++++
 4 files changed, 56 insertions(+)
 create mode 100644 arch/arm64/include/asm/ima.h
 create mode 100644 arch/arm64/kernel/ima_kexec.c

diff --git a/arch/arm64/include/asm/ima.h b/arch/arm64/include/asm/ima.h
new file mode 100644
index 000000000000..507fc94ddaba
--- /dev/null
+++ b/arch/arm64/include/asm/ima.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2019 Microsoft Corporation
+ *
+ * Author: Prakhar Srivastava <prsriva@linux.microsoft.com>
+ *
+ */
+#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);
+#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/Makefile b/arch/arm64/kernel/Makefile
index a561cbb91d4d..39c5d99b49fc 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -62,6 +62,7 @@ obj-$(CONFIG_ARM_SDE_INTERFACE)		+= sdei.o
 obj-$(CONFIG_ARM64_SSBD)		+= ssbd.o
 obj-$(CONFIG_ARM64_PTR_AUTH)		+= pointer_auth.o
 obj-$(CONFIG_SHADOW_CALL_STACK)		+= scs.o
+obj-$(CONFIG_IMA_KEXEC)			+= ima_kexec.o
 
 obj-y					+= vdso/ probes/
 obj-$(CONFIG_COMPAT_VDSO)		+= vdso32/
diff --git a/arch/arm64/kernel/ima_kexec.c b/arch/arm64/kernel/ima_kexec.c
new file mode 100644
index 000000000000..1847f1230710
--- /dev/null
+++ b/arch/arm64/kernel/ima_kexec.c
@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2019 Microsoft Corporation
+ *
+ * Author: Prakhar Srivastava <prsriva@linux.microsoft.com>
+ *
+ * File: ima_kexec.c
+ *       Defines IMA kexec functions.
+ */
+
+#include <linux/kernel.h>
+#include <linux/kexec.h>
+#include <linux/types.h>
+#include <asm/ima.h>
+
+/**
+ * arch_ima_add_kexec_buffer - do arch-specific steps to add the IMA buffer
+ *
+ * @image: kimage structure to set ima buffer information in for kexec
+ * @load_addr: Start address of the IMA buffer
+ * @size: size of 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;
+}
-- 
2.28.0

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

[Lakshmi Ramasubramanian]

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

Re: [PATCH v6 1/3] powerpc: Refactor kexec functions to move arch independent code to IMA

[Thiago Jung Bauermann]

Hello Lakshmi,

The code itself is good, I have just some minor comments about it.

But movement of powerpc code is unfortunately creating some issues. More
details below.

Lakshmi Ramasubramanian <nramas@linux.microsoft.com> writes:

> diff --git a/arch/powerpc/kexec/ima.c b/arch/powerpc/kexec/ima.c
> index 720e50e490b6..467647886064 100644
> --- a/arch/powerpc/kexec/ima.c
> +++ b/arch/powerpc/kexec/ima.c
> @@ -9,6 +9,7 @@
>  #include <linux/slab.h>
>  #include <linux/kexec.h>
>  #include <linux/of.h>
> +#include <linux/ima.h>
>  #include <linux/memblock.h>
>  #include <linux/libfdt.h>
>  
> @@ -28,105 +29,6 @@ static int get_addr_size_cells(int *addr_cells, int *size_cells)
>  	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");
> -}
> -

With this change if CONFIG_IMA=y but CONFIG_IMA_KEXEC=n, this file will
only have static int get_addr_size_cells() as its contents, which isn't
useful (and will print a warning about the function not being used). You
should change the Makefile to only build this file if CONFIG_IMA_KEXEC=y.
Then you can also remove the #ifdef CONFIG_IMA_KEXEC/#endif within it as
well.

>  #ifdef CONFIG_IMA_KEXEC
>  /**
>   * arch_ima_add_kexec_buffer - do arch-specific steps to add the IMA buffer
> @@ -179,7 +81,7 @@ 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);
> +	ima_remove_kexec_buffer(fdt, chosen_node);
>  	if (!image->arch.ima_buffer_size)
>  		return 0;
>  
> @@ -201,7 +103,7 @@ int setup_ima_buffer(const struct kimage *image, void *fdt, int chosen_node)
>  	if (ret)
>  		return ret;
>  
> -	ret = fdt_setprop(fdt, chosen_node, "linux,ima-kexec-buffer", value,
> +	ret = fdt_setprop(fdt, chosen_node, FDT_PROP_IMA_KEXEC_BUFFER, value,
>  			  entry_size);
>  	if (ret < 0)
>  		return -EINVAL;

<snip>

> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 9e93bef52968..00a60dcc7075 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -223,8 +223,19 @@ extern int crash_exclude_mem_range(struct crash_mem *mem,
>  				   unsigned long long mend);
>  extern int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
>  				       void **addr, unsigned long *sz);
> +
> +extern int delete_fdt_mem_rsv(void *fdt, unsigned long start,
> +			      unsigned long size);
>  #endif /* CONFIG_KEXEC_FILE */
>  
> +#ifndef CONFIG_KEXEC_FILE

I would use an `#else /* CONFIG_KEXEC_FILE */` here instead of #endif / #ifndef

> +static inline int delete_fdt_mem_rsv(void *fdt, unsigned long start,
> +				     unsigned long size)
> +{
> +	return 0;
> +}
> +#endif /* ifndef CONFIG_KEXEC_FILE */
> +
>  #ifdef CONFIG_KEXEC_ELF
>  struct kexec_elf_info {
>  	/*
> diff --git a/include/linux/libfdt.h b/include/linux/libfdt.h
> index 90ed4ebfa692..75fb40aa013b 100644
> --- a/include/linux/libfdt.h
> +++ b/include/linux/libfdt.h
> @@ -5,4 +5,7 @@
>  #include <linux/libfdt_env.h>
>  #include "../../scripts/dtc/libfdt/libfdt.h"
>  
> +/* Common device tree properties */
> +#define FDT_PROP_IMA_KEXEC_BUFFER	"linux,ima-kexec-buffer"
> +
>  #endif /* _INCLUDE_LIBFDT_H_ */
> diff --git a/security/integrity/ima/Makefile b/security/integrity/ima/Makefile
> index 67dabca670e2..05719fd28aec 100644
> --- a/security/integrity/ima/Makefile
> +++ b/security/integrity/ima/Makefile
> @@ -7,10 +7,11 @@
>  obj-$(CONFIG_IMA) += ima.o
>  
>  ima-y := ima_fs.o ima_queue.o ima_init.o ima_main.o ima_crypto.o ima_api.o \
> -	 ima_policy.o ima_template.o ima_template_lib.o
> +	 ima_policy.o ima_template.o ima_template_lib.o ima_fdt.o
>  ima-$(CONFIG_IMA_APPRAISE) += ima_appraise.o
>  ima-$(CONFIG_IMA_APPRAISE_MODSIG) += ima_modsig.o
>  ima-$(CONFIG_HAVE_IMA_KEXEC) += ima_kexec.o
>  ima-$(CONFIG_IMA_BLACKLIST_KEYRING) += ima_mok.o
>  ima-$(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) += ima_asymmetric_keys.o
>  ima-$(CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS) += ima_queue_keys.o
> +ima-$(CONFIG_KEXEC_FILE) += ima_kexec_file.o

Even though you are using CONFIG_KEXEC_FILE here, AFAIK this will break
the powerpc build in the case of CONFIG_IMA=n and CONFIG_KEXEC_FILE=y
because the build system won't visit security/integrity/ima in that
case.

<snip>

> +/**
> + * ima_remove_kexec_buffer - remove the IMA buffer property and
> + *			     reservation from @fdt
> + *
> + * @fdt: Flattened Device Tree to update
> + * @chosen_node: Offset to the chosen node in the device tree
> + *
> + * The IMA measurement buffer is of no use to a subsequent kernel,
> + * so we always remove it from the device tree.
> + */
> +void ima_remove_kexec_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_IMA_KEXEC_BUFFER, &len);
> +	if (!prop) {
> +		pr_err("Unable to find the ima kexec buffer node\n");

It's not an error if there's no IMA kexec buffer node. In case the
previous kernel didn't pass a buffer to this kernel there won't be one,
and it's fine. You should remove this pr_err().

> +		return;
> +	}
> +
> +	ret = do_get_kexec_buffer(prop, len, &addr, &size);
> +	fdt_delprop(fdt, chosen_node, FDT_PROP_IMA_KEXEC_BUFFER);
> +	if (ret) {
> +		pr_err("Unable to delete the ima kexec buffer node\n");
> +		return;
> +	}
> +
> +	ret = delete_fdt_mem_rsv(fdt, addr, size);
> +	if (!ret)
> +		pr_err("Removed old IMA buffer reservation.\n");

Here you're printing an error when the function actually succeeded. You
should either change this back to a pr_debug(), or remove it.

> +}
> diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
> index 121de3e04af2..ed70f99aeedc 100644
> --- a/security/integrity/ima/ima_kexec.c
> +++ b/security/integrity/ima/ima_kexec.c
> @@ -10,8 +10,66 @@
>  #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 <linux/ima.h>
>  #include "ima.h"
>  
> +/**
> + * 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.
> + */
> +static 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_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
> + */
> +static 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_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);
> +
> +}
> +

Since you created ima_fdt.c, shouldn't the two functions above go in
that file instead of here, since they work with the device tree?

>  #ifdef CONFIG_IMA_KEXEC
>  static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
>  				     unsigned long segment_size)
> diff --git a/security/integrity/ima/ima_kexec_file.c b/security/integrity/ima/ima_kexec_file.c
> new file mode 100644
> index 000000000000..225e913e6ef2
> --- /dev/null
> +++ b/security/integrity/ima/ima_kexec_file.c
> @@ -0,0 +1,51 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2020 Microsoft Corporation
> + *
> + * Author: Lakshmi Ramasubramanian (nramas@linux.microsoft.com)
> + *
> + * ima_kexec_file.c
> + *	Implements functions to handle device tree operations
> + */
> +
> +#include <linux/libfdt.h>
> +#include <linux/kexec.h>
> +#include <linux/types.h>
> +
> +/**
> + * delete_fdt_mem_rsv - delete memory reservation with given address and size
> + *
> + * @fdt: Flattened Device Tree to update
> + * @start: Starting address of the property to update

s/property to update/reservation to delete/

> + * @size: Size of the buffer corresponding to the given property

s/buffer corresponding to the given property/reservation to delete/

> + *
> + * Return: 0 on success, or negative errno on error.
> + */
> +int delete_fdt_mem_rsv(void *fdt, unsigned long start, unsigned long size)

This function can't go in an IMA-specific directory, because it's used
in arch/powerpc/kexec/file_load.c even if IMA isn't enabled.

I'm not sure where would be a good place for it. Perhaps a new file
called kernel/kexec_file_fdt.c?

> +{
> +	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;
> +			}
> +
> +			pr_err("Freed the reserved memory at %lu of size %lu\n",
> +				start, size);

This isn't an error. You should change it to a pr_debug() or remove it.

> +			return 0;
> +		}
> +	}
> +
> +	return -ENOENT;
> +}


-- 
Thiago Jung Bauermann
IBM Linux Technology Center

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

[Thiago Jung Bauermann]

Lakshmi Ramasubramanian <nramas@linux.microsoft.com> writes:

> 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>

Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>

-- 
Thiago Jung Bauermann
IBM Linux Technology Center

Re: [PATCH v6 0/3] Carry forward IMA measurement log on kexec on ARM64

[Mimi Zohar]

[Cc'ing Nayna Jain, linuxppc-dev@lists.ozlabs.org]

Hi Lakshmi,

On Tue, 2020-09-08 at 16:08 -0700, Lakshmi Ramasubramanian wrote:
> On kexec file load Integrity Measurement Architecture(IMA) subsystem
> may verify the IMA signature of the kernel and initramfs, and measure
> it. The command line parameters passed to the kernel in the kexec call
> may also be measured by IMA. A remote attestation service can verify
> the measurement through the IMA log and the TPM PCR data. This can be
> achieved only if the IMA measurement log is carried over from
> the current kernel to the next kernel across the kexec call.
> However in the current implementation the IMA measurement logs are not
> carried over on ARM64 platforms. Therefore a remote attestation service
> cannot verify the authenticity of the running kernel on ARM64 platforms
> when the kernel is updated through the kexec system call.
> 
> This patch series adds support for carrying forward the IMA measurement
> log on kexec on ARM64. powerpc already supports carrying forward
> the IMA measurement log on kexec.
> 
> This series refactors the platform independent code defined for powerpc
> such that it can be reused for ARM64 as well. A chosen node namely
> "linux,ima-kexec-buffer" is added to the DTB for ARM64 to hold
> the address and the size of the memory reserved to carry
> the IMA measurement log.
> 
> This patch series has been tested for ARM64 platform using QEMU.
> I would like help from the community for testing this change on powerpc.
> Thanks.

Getting access to and upgrading our group's Power system firmware took
time due to limited employee site access.  Confirmed, with these
patches applied, ima-evm-utils still properly verifies carrying the IMA
measurement list across kexec.

I plan on reviewing this patch set shortly.

thanks,

Mimi

> 
> This series is based on commit f4d51dffc6c0 ("Linux 5.9-rc4") in
> https://github.com/torvalds/linux "master" branch.
> 
> Changelog:
> 
> v6:
>   - Remove any existing FDT_PROP_IMA_KEXEC_BUFFER property in the device
>     tree and also its corresponding memory reservation in the currently
>     running kernel.
>   - Moved the function remove_ima_buffer() defined for powerpc to IMA
>     and renamed the function to ima_remove_kexec_buffer(). Also, moved
>     delete_fdt_mem_rsv() from powerpc to IMA.
> 
> v5:
>   - Merged get_addr_size_cells() and do_get_kexec_buffer() into a single
>     function when moving the arch independent code from powerpc to IMA
>   - Reverted the change to use FDT functions in powerpc code and added
>     back the original code in get_addr_size_cells() and
>     do_get_kexec_buffer() for powerpc.
>   - Added fdt_add_mem_rsv() for ARM64 to reserve the memory for
>     the IMA log buffer during kexec.
>   - Fixed the warning reported by kernel test bot for ARM64
>     arch_ima_add_kexec_buffer() - moved this function to a new file
>     namely arch/arm64/kernel/ima_kexec.c
> 
> v4:
>   - Submitting the patch series on behalf of the original author
>     Prakhar Srivastava <prsriva@linux.microsoft.com>
>   - Moved FDT_PROP_IMA_KEXEC_BUFFER ("linux,ima-kexec-buffer") to
>     libfdt.h so that it can be shared by multiple platforms.
> 
> v3:
> Breakup patches further into separate patches.
>   - Refactoring non architecture specific code out of powerpc
>   - Update powerpc related code to use fdt functions
>   - Update IMA buffer read related code to use of functions
>   - Add support to store the memory information of the IMA
>     measurement logs to be carried forward.
>   - Update the property strings to align with documented nodes
>     https://github.com/devicetree-org/dt-schema/pull/46
> 
> v2:
>   Break patches into separate patches.
>   - Powerpc related Refactoring
>   - Updating the docuemntation for chosen node
>   - Updating arm64 to support IMA buffer pass
> 
> v1:
>   Refactoring carrying over IMA measuremnet logs over Kexec. This patch
>     moves the non-architecture specific code out of powerpc and adds to
>     security/ima.(Suggested by Thiago)
>   Add Documentation regarding the ima-kexec-buffer node in the chosen
>     node documentation
> 
> v0:
>   Add a layer of abstraction to use the memory reserved by device tree
>     for ima buffer pass.
>   Add support for ima buffer pass using reserved memory for arm64 kexec.
>     Update the arch sepcific code path in kexec file load to store the
>     ima buffer in the reserved memory. The same reserved memory is read
>     on kexec or cold boot.
> 
> Lakshmi Ramasubramanian (3):
>   powerpc: Refactor kexec functions to move arch independent code to IMA
>   arm64: Store IMA log information in kimage used for kexec
>   arm64: Add IMA kexec buffer to DTB
> 
>  arch/arm64/Kconfig                      |   1 +
>  arch/arm64/include/asm/ima.h            |  18 ++++
>  arch/arm64/include/asm/kexec.h          |   3 +
>  arch/arm64/kernel/Makefile              |   1 +
>  arch/arm64/kernel/ima_kexec.c           |  34 ++++++++
>  arch/arm64/kernel/machine_kexec_file.c  |  18 ++++
>  arch/powerpc/include/asm/ima.h          |  11 +--
>  arch/powerpc/include/asm/kexec.h        |   1 -
>  arch/powerpc/kexec/file_load.c          |  33 +-------
>  arch/powerpc/kexec/ima.c                | 104 +-----------------------
>  include/linux/ima.h                     |   2 +
>  include/linux/kexec.h                   |  11 +++
>  include/linux/libfdt.h                  |   3 +
>  security/integrity/ima/Makefile         |   3 +-
>  security/integrity/ima/ima.h            |   2 +
>  security/integrity/ima/ima_fdt.c        |  80 ++++++++++++++++++
>  security/integrity/ima/ima_kexec.c      |  58 +++++++++++++
>  security/integrity/ima/ima_kexec_file.c |  51 ++++++++++++
>  18 files changed, 289 insertions(+), 145 deletions(-)
>  create mode 100644 arch/arm64/include/asm/ima.h
>  create mode 100644 arch/arm64/kernel/ima_kexec.c
>  create mode 100644 security/integrity/ima/ima_fdt.c
>  create mode 100644 security/integrity/ima/ima_kexec_file.c
>