Carry forward IMA measurement log on kexec on ARM64

The functions 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.

remove_ima_buffer() and delete_fdt_mem_rsv() are used to remove the IMA log entry from the device tree and free the memory reserved for the log. These functions need to be defined even if the current kernel does not support carrying forward IMA log across kexec since the previous kernel could have supported that and therefore the current kernel needs to free the allocation.

Rename remove_ima_buffer() to remove_ima_kexec_buffer(). Define remove_ima_kexec_buffer() and delete_fdt_mem_rsv() in drivers/of/fdt.c. A later patch in this series will use these functions to free the allocation, if any, made by the previous kernel for ARM64.

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.

Quoted 4 lines

The functions 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.

^ ... logs on kexec, do not have architecture specific code, but are currently limited to powerpc.

Quoted 8 lines

remove_ima_buffer() and delete_fdt_mem_rsv() are used to remove the IMA log entry from the device tree and free the memory reserved for the log. These functions need to be defined even if the current kernel does not support carrying forward IMA log across kexec since the previous kernel could have supported that and therefore the current kernel needs to free the allocation.

The first paragraph describes these function as "handle carrying forward the IMA measurement logs on kexec", while this paragraph says "are used to remove the IMA log entry". Consider listing all of the functions being moved in the first paragrah, then "handle carrying forward" could be expanded to "carrying ... and removing".

Quoted 6 lines

Rename remove_ima_buffer() to remove_ima_kexec_buffer(). Define remove_ima_kexec_buffer() and delete_fdt_mem_rsv() in drivers/of/fdt.c. A later patch in this series will use these functions to free the allocation, if any, made by the previous kernel for ARM64.

- ^Define -> Move
- Three functions are being moved, but only two are listed. "do_get_kexec_buffer" is not mentioned.
- Don't refer to a later patch, but explain the purpose here. For example, "Move ... , making them accessible to other archs."

Quoted 6 lines

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.

The above two paragraphs describe renaming a function and defining a chosen node. These two preparatory changes should be made, independently of each other, prior to this patch. This patch should be limited to moving code, with the subject line truncated to "move arch independent code to drivers/of".

On 11/3/20 6:55 AM, Mimi Zohar wrote:

Hi Mimi,

Thanks for reviewing the patches.

Quoted 8 lines · Lakshmi Ramasubramanian

Quoted 4 lines

The functions 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.

^ ... logs on kexec, do not have architecture specific code, but are currently limited to powerpc.

Will make this change.

Quoted 9 lines

Quoted 8 lines

remove_ima_buffer() and delete_fdt_mem_rsv() are used to remove the IMA log entry from the device tree and free the memory reserved for the log. These functions need to be defined even if the current kernel does not support carrying forward IMA log across kexec since the previous kernel could have supported that and therefore the current kernel needs to free the allocation.

Quoted 5 lines

The first paragraph describes these function as "handle carrying forward the IMA measurement logs on kexec", while this paragraph says "are used to remove the IMA log entry". Consider listing all of the functions being moved in the first paragrah, then "handle carrying forward" could be expanded to "carrying ... and removing".

Sure.

Quoted 8 lines

Quoted 7 lines

Rename remove_ima_buffer() to remove_ima_kexec_buffer(). Define remove_ima_kexec_buffer() and delete_fdt_mem_rsv() in drivers/of/fdt.c. A later patch in this series will use these functions to free the allocation, if any, made by the previous kernel for ARM64.

Quoted 5 lines

- ^Define -> Move
- Three functions are being moved, but only two are listed. "do_get_kexec_buffer" is not mentioned.
- Don't refer to a later patch, but explain the purpose here. For example, "Move ... , making them accessible to other archs."

Sure.

Quoted 7 lines

Quoted 6 lines

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.

Quoted 6 lines

The above two paragraphs describe renaming a function and defining a chosen node. These two preparatory changes should be made, independently of each other, prior to this patch. This patch should be limited to moving code, with the subject line truncated to "move arch independent code to drivers/of".

Just to be clear -

Split this patch into 3 parts as listed below:

PATCH #1: Rename remove_ima_buffer() to remove_ima_kexec_buffer() PATCH #2: Define the chosen node
PATCH #3: Move the functions to drivers/of/fdt.c

Sure - I'll make the above changes and update patch descriptions accordingly.

Quoted 30 lines · Lakshmi Ramasubramanian

On 11/3/20 6:55 AM, Mimi Zohar wrote:

Hi Mimi,

Thanks for reviewing the patches.

Quoted 8 lines · Lakshmi Ramasubramanian

Quoted 4 lines

The functions 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.

^ ... logs on kexec, do not have architecture specific code, but are currently limited to powerpc.

Will make this change.

Quoted 14 lines

Quoted 8 lines

remove_ima_buffer() and delete_fdt_mem_rsv() are used to remove the IMA log entry from the device tree and free the memory reserved for the log. These functions need to be defined even if the current kernel does not support carrying forward IMA log across kexec since the previous kernel could have supported that and therefore the current kernel needs to free the allocation.

The first paragraph describes these function as "handle carrying forward the IMA measurement logs on kexec", while this paragraph says "are used to remove the IMA log entry". Consider listing all of the functions being moved in the first paragrah, then "handle carrying forward" could be expanded to "carrying ... and removing".

Quoted 1 line

Sure.

Sorry, even with naming do_get_kexec_buffer(), the measurement list
isn't being carried across kexec. Please adjust the wording.

Quoted 32 lines

Quoted 9 lines

Quoted 8 lines

Rename remove_ima_buffer() to remove_ima_kexec_buffer(). Define remove_ima_kexec_buffer() and delete_fdt_mem_rsv() in drivers/of/fdt.c. A later patch in this series will use these functions to free the allocation, if any, made by the previous kernel for ARM64.

Quoted 5 lines

- ^Define -> Move
- Three functions are being moved, but only two are listed. "do_get_kexec_buffer" is not mentioned.
- Don't refer to a later patch, but explain the purpose here. For example, "Move ... , making them accessible to other archs."

Sure.

Quoted 7 lines

Quoted 6 lines

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.

Quoted 6 lines

The above two paragraphs describe renaming a function and defining a chosen node. These two preparatory changes should be made, independently of each other, prior to this patch. This patch should be limited to moving code, with the subject line truncated to "move arch independent code to drivers/of".

Just to be clear -

Quoted 5 lines

Split this patch into 3 parts as listed below:

PATCH #1: Rename remove_ima_buffer() to remove_ima_kexec_buffer() PATCH #2: Define the chosen node
PATCH #3: Move the functions to drivers/of/fdt.c

yes, thanks.

The functions 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.

remove_ima_buffer() and delete_fdt_mem_rsv() are used to remove the IMA log entry from the device tree and free the memory reserved for the log. These functions need to be defined even if the current kernel does not support carrying forward IMA log across kexec since the previous kernel could have supported that and therefore the current kernel needs to free the allocation.

Rename remove_ima_buffer() to remove_ima_kexec_buffer(). Define remove_ima_kexec_buffer() and delete_fdt_mem_rsv() in drivers/of/fdt.c. A later patch in this series will use these functions to free the allocation, if any, made by the previous kernel for ARM64.

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 <[email protected]>

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

Signed-off-by Lakshmi Ramasubramanian <[email protected]>

Reported-by kernel test robot <[email protected]> error: kernel/kexec_file_fdt.c:30: undefined reference to `fdt_num_mem_rsv'

---
 arch/powerpc/include/asm/ima.h   |  10 +--
 arch/powerpc/include/asm/kexec.h |   1 -
 arch/powerpc/kexec/file_load.c   |  33 +---------
 arch/powerpc/kexec/ima.c         |  55 +++-------------
 drivers/of/fdt.c                 | 110 +++++++++++++++++++++++++++++++
 include/linux/kexec.h            |  24 +++++++
 include/linux/libfdt.h           |   3 +
 7 files changed, 149 insertions(+), 87 deletions(-)

arch/powerpc/include/asm/ima.h +3 -7

index ead488cf3981..6355a85a3289 100644
@@ -2,17 +2,13 @@
 #ifndef _ASM_POWERPC_IMA_H
 #define _ASM_POWERPC_IMA_H
 
+#include <linux/kexec.h>
+
 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 +18,7 @@ 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);
+	remove_ima_kexec_buffer(fdt, chosen_node);
 	return 0;
 }
 #endif /* CONFIG_IMA_KEXEC */

arch/powerpc/include/asm/kexec.h +0 -1

index 55d6ede30c19..7c223031ecdd 100644
@@ -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;

arch/powerpc/kexec/file_load.c +1 -32

index 9a232bc36c8f..7a17655c530e 100644
@@ -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.

arch/powerpc/kexec/ima.c +8 -47

index 720e50e490b6..2b790230ea15 100644
@@ -11,6 +11,8 @@
 #include <linux/of.h>
 #include <linux/memblock.h>
 #include <linux/libfdt.h>
+#include <linux/ima.h>
+#include <asm/ima.h>
 
 static int get_addr_size_cells(int *addr_cells, int *size_cells)
 {

@@ -28,24 +30,6 @@ 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.

@@ -100,37 +84,14 @@ int ima_free_kexec_buffer(void)
 
 }
 
-/**
- * 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
  *
+ * @image: kimage struct to set IMA buffer data
+ * @load_addr: Starting address where IMA buffer is loaded at
+ * @size: Number of bytes in the IMA buffer
+ *
  * Architectures should use this function to pass on the IMA buffer
  * information to the next kernel.
  *

@@ -179,7 +140,7 @@ 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_kexec_buffer(fdt, chosen_node);
 	if (!image->arch.ima_buffer_size)
 		return 0;
 

@@ -201,7 +162,7 @@ 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;

drivers/of/fdt.c +1 -0

index 4602e467ca8b..d2e6f8ce0e42 100644
@@ -25,6 +25,7 @@
 #include <linux/serial_core.h>
 #include <linux/sysfs.h>
 #include <linux/random.h>
+#include <linux/kexec.h>
 
 #include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
 #include <asm/page.h>

drivers/of/fdt.c +5 -0

+/**
+ * do_get_kexec_buffer - Get address and size of IMA kexec buffer
+ *
+ * @prop: IMA kexec buffer node in the device tree
+ * @len: Size of the given device tree node property

drivers/of/fdt.c +64 -0

+	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_debug("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_debug("Removed old IMA buffer reservation.\n");
+}
+#endif /* CONFIG_HAVE_IMA_KEXEC */
+
+#ifdef CONFIG_KEXEC_FILE
+/**
+ * delete_fdt_mem_rsv - delete memory reservation with given address and size
+ *
+ * @fdt: Flattened Device Tree to update
+ * @start: Starting address of the reservation to delete
+ * @size: Size of the 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)
+{
+	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_debug("Freed reserved memory at %lu of size %lu\n",
+				 start, size);
+			return 0;
+		}
+	}
+
+	return -ENOENT;
+}
+#endif /* CONFIG_KEXEC_FILE */
+
 #endif /* CONFIG_OF_EARLY_FLATTREE */

include/linux/kexec.h +0 -0

index 9e93bef52968..6c6c6791a7ba 100644

include/linux/kexec.h +23 -0

+extern void remove_ima_kexec_buffer(void *fdt, int chosen_node);
+extern int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
+			       size_t *size);
+#else
+static inline void remove_ima_kexec_buffer(void *fdt, int chosen_node) {}
+static inline int do_get_kexec_buffer(const void *prop, int len,
+				      unsigned long *addr, size_t *size)
+{
+	return -EOPNOTSUPP;
+}
+#endif /* CONFIG_OF_EARLY_FLATTREE && CONFIG_HAVE_IMA_KEXEC */
+
+#if defined(CONFIG_OF_EARLY_FLATTREE) && defined(CONFIG_KEXEC_FILE)
+extern int delete_fdt_mem_rsv(void *fdt, unsigned long start,
+			      unsigned long size);
+#else
+static inline int delete_fdt_mem_rsv(void *fdt, unsigned long start,
+				     unsigned long size)
+{
+	return 0;
+}
+#endif /* CONFIG_OF_EARLY_FLATTREE && CONFIG_KEXEC_FILE */
+
 #endif /* !defined(__ASSEBMLY__) */
 
 #endif /* LINUX_KEXEC_H */

include/linux/libfdt.h +0 -0

index 90ed4ebfa692..75fb40aa013b 100644

include/linux/libfdt.h +1 -0

+
 #endif /* _INCLUDE_LIBFDT_H_ */

Signature · 1 line

2.29.0

Quoted 22 lines

The functions 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.

remove_ima_buffer() and delete_fdt_mem_rsv() are used to remove the IMA log entry from the device tree and free the memory reserved for the log. These functions need to be defined even if the current kernel does not support carrying forward IMA log across kexec since the previous kernel could have supported that and therefore the current kernel needs to free the allocation.

Rename remove_ima_buffer() to remove_ima_kexec_buffer(). Define remove_ima_kexec_buffer() and delete_fdt_mem_rsv() in drivers/of/fdt.c. A later patch in this series will use these functions to free the allocation, if any, made by the previous kernel for ARM64.

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.

Quoted 4 lines

Co-developed-by Prakhar Srivastava <[email protected]>

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

Signed-off-by Lakshmi Ramasubramanian <[email protected]>

Reported-by kernel test robot <[email protected]> error: kernel/kexec_file_fdt.c:30: undefined reference to `fdt_num_mem_rsv'

This should be added for a commit fixing the reported problem. 0-day didn't report what this patch implements.

Quoted 221 lines

---
  arch/powerpc/include/asm/ima.h   |  10 +--
  arch/powerpc/include/asm/kexec.h |   1 -
  arch/powerpc/kexec/file_load.c   |  33 +---------
  arch/powerpc/kexec/ima.c         |  55 +++-------------
  drivers/of/fdt.c                 | 110 +++++++++++++++++++++++++++++++
  include/linux/kexec.h            |  24 +++++++
  include/linux/libfdt.h           |   3 +
  7 files changed, 149 insertions(+), 87 deletions(-)

arch/powerpc/include/asm/ima.h +3 -7

index ead488cf3981..6355a85a3289 100644
@@ -2,17 +2,13 @@
  #ifndef _ASM_POWERPC_IMA_H
  #define _ASM_POWERPC_IMA_H
 
+#include <linux/kexec.h>
+
  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 +18,7 @@ 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);
+	remove_ima_kexec_buffer(fdt, chosen_node);
  	return 0;
  }
  #endif /* CONFIG_IMA_KEXEC */

arch/powerpc/include/asm/kexec.h +0 -1

index 55d6ede30c19..7c223031ecdd 100644
@@ -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;

arch/powerpc/kexec/file_load.c +1 -32

index 9a232bc36c8f..7a17655c530e 100644
@@ -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.

arch/powerpc/kexec/ima.c +8 -47

index 720e50e490b6..2b790230ea15 100644
@@ -11,6 +11,8 @@
  #include <linux/of.h>
  #include <linux/memblock.h>
  #include <linux/libfdt.h>
+#include <linux/ima.h>
+#include <asm/ima.h>
 
  static int get_addr_size_cells(int *addr_cells, int *size_cells)
  {

@@ -28,24 +30,6 @@ 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.

@@ -100,37 +84,14 @@ int ima_free_kexec_buffer(void)
 
  }
 
-/**
- * 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
   *
+ * @image: kimage struct to set IMA buffer data
+ * @load_addr: Starting address where IMA buffer is loaded at
+ * @size: Number of bytes in the IMA buffer
+ *
   * Architectures should use this function to pass on the IMA buffer
   * information to the next kernel.
   *

@@ -179,7 +140,7 @@ 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_kexec_buffer(fdt, chosen_node);
  	if (!image->arch.ima_buffer_size)
  		return 0;
 

@@ -201,7 +162,7 @@ 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;

drivers/of/fdt.c +1 -0

index 4602e467ca8b..d2e6f8ce0e42 100644
@@ -25,6 +25,7 @@
  #include <linux/serial_core.h>
  #include <linux/sysfs.h>
  #include <linux/random.h>
+#include <linux/kexec.h>
 
  #include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
  #include <asm/page.h>

@@ -1289,4 +1290,113 @@ static int __init of_fdt_raw_init(void)
  late_initcall(of_fdt_raw_init);
  #endif
 

drivers/of/fdt.c static int __init of_fdt_raw_init(void) · line 1293

Quoted 1 line

drivers/of/fdt.c +1 -0

+#ifdef CONFIG_HAVE_IMA_KEXEC

Can we avoid #ifdef and use IS_ENABLED() within the functions?

Quoted 10 lines

drivers/of/fdt.c +9 -0

+/**
+ * do_get_kexec_buffer - Get address and size of IMA kexec buffer
+ *
+ * @prop: IMA kexec buffer node in the device tree
+ * @len: Size of the given device tree node property
+ * @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,

drivers/of/fdt.c static int __init of_fdt_raw_init(void) · line 1308

Quoted 6 lines

drivers/of/fdt.c +6 -0

+			size_t *size)
+{
+	int addr_cells, size_cells;
+	struct device_node *root;
+
+	root = of_find_node_by_path("/");

The code in fdt.c operates on flat trees. This is an unflattened tree.

Quoted 4 lines

drivers/of/fdt.c +3 -0

+	if (!root)
+		return -EINVAL;
+

drivers/of/fdt.c static int __init of_fdt_raw_init(void) · line 1321

Quoted 10 lines

drivers/of/fdt.c +10 -0

+	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);

There's nothing in this function specific to 'kexec buffer'.

This interface is kind of broken. 'prop' could come from anywhere in the tree, but we always read the root address and size cells. Those only apply to immediate child node properties. And anything other than immediate root child nodes, there needs to be address translation.

drivers/of/fdt.c static int __init of_fdt_raw_init(void) · line 1328

Quoted 7 lines

drivers/of/fdt.c +7 -0

+
+	return 0;
+}
+
+/**
+ * remove_ima_kexec_buffer - remove the IMA buffer property and
+ *			     reservation from @fdt

IIRC, kerneldoc requires this to be one line.

drivers/of/fdt.c static int __init of_fdt_raw_init(void) · line 1337

Quoted 10 lines

drivers/of/fdt.c +9 -0

+ *
+ * @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 remove_ima_kexec_buffer(void *fdt, int chosen_node)
+{

Can't this go in some common kexec code?

Quoted 74 lines

drivers/of/fdt.c +64 -0

+	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_debug("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_debug("Removed old IMA buffer reservation.\n");
+}
+#endif /* CONFIG_HAVE_IMA_KEXEC */
+
+#ifdef CONFIG_KEXEC_FILE
+/**
+ * delete_fdt_mem_rsv - delete memory reservation with given address and size
+ *
+ * @fdt: Flattened Device Tree to update
+ * @start: Starting address of the reservation to delete
+ * @size: Size of the 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)
+{
+	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_debug("Freed reserved memory at %lu of size %lu\n",
+				 start, size);
+			return 0;
+		}
+	}
+
+	return -ENOENT;
+}
+#endif /* CONFIG_KEXEC_FILE */
+
  #endif /* CONFIG_OF_EARLY_FLATTREE */

include/linux/kexec.h +0 -0

index 9e93bef52968..6c6c6791a7ba 100644
@@ -407,6 +407,30 @@ static inline int kexec_crash_loaded(void) { return 0; }
  #define kexec_in_progress false
  #endif /* CONFIG_KEXEC_CORE */
 

include/linux/kexec.h static inline int kexec_crash_loaded(void) { return 0; } · line 410

Quoted 1 line

include/linux/kexec.h +1 -0

+#if defined(CONFIG_OF_EARLY_FLATTREE) && defined(CONFIG_HAVE_IMA_KEXEC)

CONFIG_OF_EARLY_FLATTREE is wrong because that's all early boot (i.e. init section) functions.

If these functions are implemented in fdt.c, then this is the wrong header. But it's the implementation that should move.

Quoted 35 lines

include/linux/kexec.h +23 -0

+extern void remove_ima_kexec_buffer(void *fdt, int chosen_node);
+extern int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
+			       size_t *size);
+#else
+static inline void remove_ima_kexec_buffer(void *fdt, int chosen_node) {}
+static inline int do_get_kexec_buffer(const void *prop, int len,
+				      unsigned long *addr, size_t *size)
+{
+	return -EOPNOTSUPP;
+}
+#endif /* CONFIG_OF_EARLY_FLATTREE && CONFIG_HAVE_IMA_KEXEC */
+
+#if defined(CONFIG_OF_EARLY_FLATTREE) && defined(CONFIG_KEXEC_FILE)
+extern int delete_fdt_mem_rsv(void *fdt, unsigned long start,
+			      unsigned long size);
+#else
+static inline int delete_fdt_mem_rsv(void *fdt, unsigned long start,
+				     unsigned long size)
+{
+	return 0;
+}
+#endif /* CONFIG_OF_EARLY_FLATTREE && CONFIG_KEXEC_FILE */
+
  #endif /* !defined(__ASSEBMLY__) */
 
  #endif /* LINUX_KEXEC_H */

include/linux/libfdt.h +0 -0

index 90ed4ebfa692..75fb40aa013b 100644
@@ -5,4 +5,7 @@
  #include <linux/libfdt_env.h>
  #include "../../scripts/dtc/libfdt/libfdt.h"
 

include/linux/libfdt.h line 9

Quoted 2 lines

include/linux/libfdt.h +2 -0

+/* Common device tree properties */
+#define FDT_PROP_IMA_KEXEC_BUFFER	"linux,ima-kexec-buffer"

This is not part of libfdt. We generally don't do defines for DT strings.

Quoted 6 lines

include/linux/libfdt.h +1 -0

+
  #endif /* _INCLUDE_LIBFDT_H_ */

Signature · 1 line

2.29.0

On 11/4/20 2:28 PM, Rob Herring wrote:

Hi Rob,

Thanks for reviewing the patch.

Quoted 23 lines · Lakshmi Ramasubramanian

Quoted 22 lines

The functions 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.

remove_ima_buffer() and delete_fdt_mem_rsv() are used to remove the IMA log entry from the device tree and free the memory reserved for the log. These functions need to be defined even if the current kernel does not support carrying forward IMA log across kexec since the previous kernel could have supported that and therefore the current kernel needs to free the allocation.

Rename remove_ima_buffer() to remove_ima_kexec_buffer(). Define remove_ima_kexec_buffer() and delete_fdt_mem_rsv() in drivers/of/fdt.c. A later patch in this series will use these functions to free the allocation, if any, made by the previous kernel for ARM64.

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.

Quoted 7 lines

Quoted 4 lines

Co-developed-by Prakhar Srivastava <[email protected]>

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

Signed-off-by Lakshmi Ramasubramanian <[email protected]>

Reported-by kernel test robot <[email protected]> error: kernel/kexec_file_fdt.c:30: undefined reference to `fdt_num_mem_rsv'

This should be added for a commit fixing the reported problem. 0-day didn't report what this patch implements.

I'll remove that in the updated patch I'll post.

Quoted 221 lines

Quoted 221 lines

---
  arch/powerpc/include/asm/ima.h   |  10 +--
  arch/powerpc/include/asm/kexec.h |   1 -
  arch/powerpc/kexec/file_load.c   |  33 +---------
  arch/powerpc/kexec/ima.c         |  55 +++-------------
  drivers/of/fdt.c                 | 110 +++++++++++++++++++++++++++++++
  include/linux/kexec.h            |  24 +++++++
  include/linux/libfdt.h           |   3 +
  7 files changed, 149 insertions(+), 87 deletions(-)

arch/powerpc/include/asm/ima.h +3 -7

index ead488cf3981..6355a85a3289 100644
@@ -2,17 +2,13 @@
  #ifndef _ASM_POWERPC_IMA_H
  #define _ASM_POWERPC_IMA_H
 
+#include <linux/kexec.h>
+
  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 +18,7 @@ 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);
+    remove_ima_kexec_buffer(fdt, chosen_node);
     return 0;
  }
  #endif /* CONFIG_IMA_KEXEC */

arch/powerpc/include/asm/kexec.h +0 -1

index 55d6ede30c19..7c223031ecdd 100644
@@ -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;

arch/powerpc/kexec/file_load.c +1 -32

index 9a232bc36c8f..7a17655c530e 100644
@@ -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.

arch/powerpc/kexec/ima.c +8 -47

index 720e50e490b6..2b790230ea15 100644
@@ -11,6 +11,8 @@
  #include <linux/of.h>
  #include <linux/memblock.h>
  #include <linux/libfdt.h>
+#include <linux/ima.h>
+#include <asm/ima.h>
 
  static int get_addr_size_cells(int *addr_cells, int *size_cells)
  {

@@ -28,24 +30,6 @@ 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.

@@ -100,37 +84,14 @@ int ima_free_kexec_buffer(void)
 
  }
 
-/**
- * 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
   *
+ * @image: kimage struct to set IMA buffer data
+ * @load_addr: Starting address where IMA buffer is loaded at
+ * @size: Number of bytes in the IMA buffer
+ *
   * Architectures should use this function to pass on the IMA buffer
   * information to the next kernel.
   *

@@ -179,7 +140,7 @@ 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_kexec_buffer(fdt, chosen_node);
     if (!image->arch.ima_buffer_size)
             return 0;
 

@@ -201,7 +162,7 @@ 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;

drivers/of/fdt.c +1 -0

index 4602e467ca8b..d2e6f8ce0e42 100644
@@ -25,6 +25,7 @@
  #include <linux/serial_core.h>
  #include <linux/sysfs.h>
  #include <linux/random.h>
+#include <linux/kexec.h>
 
  #include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
  #include <asm/page.h>

@@ -1289,4 +1290,113 @@ static int __init of_fdt_raw_init(void)
  late_initcall(of_fdt_raw_init);
  #endif
 

Quoted 3 lines

drivers/of/fdt.c static int __init of_fdt_raw_init(void) · line 1293

Quoted 1 line

drivers/of/fdt.c +1 -0

+#ifdef CONFIG_HAVE_IMA_KEXEC

Can we avoid #ifdef and use IS_ENABLED() within the functions?

I can use IS_ENABLED() or move the functions to another C file and conditionally build based on the CONFIG.

Quoted 10 lines

Quoted 10 lines

drivers/of/fdt.c +9 -0

+/**
+ * do_get_kexec_buffer - Get address and size of IMA kexec buffer
+ *
+ * @prop: IMA kexec buffer node in the device tree
+ * @len: Size of the given device tree node property
+ * @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,

Quoted 8 lines

drivers/of/fdt.c static int __init of_fdt_raw_init(void) · line 1308

Quoted 6 lines

drivers/of/fdt.c +6 -0

+                    size_t *size)
+{
+    int addr_cells, size_cells;
+    struct device_node *root;
+
+    root = of_find_node_by_path("/");

The code in fdt.c operates on flat trees. This is an unflattened tree.

Would it be better if I move these functions to a new C file under "drivers/of"?

Quoted 17 lines

Quoted 4 lines

drivers/of/fdt.c +3 -0

+    if (!root)
+            return -EINVAL;
+

drivers/of/fdt.c static int __init of_fdt_raw_init(void) · line 1321

Quoted 10 lines

drivers/of/fdt.c +10 -0

+    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);

There's nothing in this function specific to 'kexec buffer'.

Quoted 5 lines

This interface is kind of broken. 'prop' could come from anywhere in the tree, but we always read the root address and size cells. Those only apply to immediate child node properties. And anything other than immediate root child nodes, there needs to be address translation.

I moved this function from arch/powerpc/kexec/ima.c to here so that it can be shared by ARM64 as well. Below is one of the usage of do_get_kexec_buffer().

         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);

Is there a way to detect if the 'prop' is an immediate root child node or not so that we can handle it appropriately in this interface function?

Quoted 9 lines

drivers/of/fdt.c static int __init of_fdt_raw_init(void) · line 1328

Quoted 7 lines

drivers/of/fdt.c +7 -0

+
+    return 0;
+}
+
+/**
+ * remove_ima_kexec_buffer - remove the IMA buffer property and
+ *                       reservation from @fdt

IIRC, kerneldoc requires this to be one line.

I'll upate.

Quoted 12 lines

drivers/of/fdt.c static int __init of_fdt_raw_init(void) · line 1337

Quoted 10 lines

drivers/of/fdt.c +9 -0

+ *
+ * @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 remove_ima_kexec_buffer(void *fdt, int chosen_node)
+{

Can't this go in some common kexec code?

I'd considered moving this to "kernel", but Thiago suggested "drivers/of" is a better place. If you have suggestions for a better place, please let me know.

Note that this function needs to be available even when CONFIG_IMA is not enabled. So I can't move it to "security/integrity/ima".

Quoted 73 lines

Quoted 73 lines

drivers/of/fdt.c +64 -0

+    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_debug("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_debug("Removed old IMA buffer reservation.\n");
+}
+#endif /* CONFIG_HAVE_IMA_KEXEC */
+
+#ifdef CONFIG_KEXEC_FILE
+/**
+ * delete_fdt_mem_rsv - delete memory reservation with given address and size
+ *
+ * @fdt: Flattened Device Tree to update
+ * @start: Starting address of the reservation to delete
+ * @size: Size of the 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)
+{
+    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_debug("Freed reserved memory at %lu of size %lu\n",
+                             start, size);
+                    return 0;
+            }
+    }
+
+    return -ENOENT;
+}
+#endif /* CONFIG_KEXEC_FILE */
+
  #endif /* CONFIG_OF_EARLY_FLATTREE */

include/linux/kexec.h +0 -0

index 9e93bef52968..6c6c6791a7ba 100644
@@ -407,6 +407,30 @@ static inline int kexec_crash_loaded(void) { return 0; }
  #define kexec_in_progress false
  #endif /* CONFIG_KEXEC_CORE */
 

Quoted 7 lines

include/linux/kexec.h static inline int kexec_crash_loaded(void) { return 0; } · line 410

Quoted 1 line

include/linux/kexec.h +1 -0

+#if defined(CONFIG_OF_EARLY_FLATTREE) && defined(CONFIG_HAVE_IMA_KEXEC)

CONFIG_OF_EARLY_FLATTREE is wrong because that's all early boot (i.e. init section) functions.

If these functions are implemented in fdt.c, then this is the wrong header. But it's the implementation that should move.

If you think defining these functions in "drivers/of" is okay, I'll move them to a new C file in OF.

Would CONFIG_OF_FLATTREE be a better one to enable these ima kexec functions? "of_" and "fdt_" are the functions called by these ima kexec functions.

Quoted 36 lines

Quoted 36 lines

include/linux/kexec.h +23 -0

+extern void remove_ima_kexec_buffer(void *fdt, int chosen_node);
+extern int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
+                           size_t *size);
+#else
+static inline void remove_ima_kexec_buffer(void *fdt, int chosen_node) {}
+static inline int do_get_kexec_buffer(const void *prop, int len,
+                                  unsigned long *addr, size_t *size)
+{
+    return -EOPNOTSUPP;
+}
+#endif /* CONFIG_OF_EARLY_FLATTREE && CONFIG_HAVE_IMA_KEXEC */
+
+#if defined(CONFIG_OF_EARLY_FLATTREE) && defined(CONFIG_KEXEC_FILE)
+extern int delete_fdt_mem_rsv(void *fdt, unsigned long start,
+                          unsigned long size);
+#else
+static inline int delete_fdt_mem_rsv(void *fdt, unsigned long start,
+                                 unsigned long size)
+{
+    return 0;
+}
+#endif /* CONFIG_OF_EARLY_FLATTREE && CONFIG_KEXEC_FILE */
+
  #endif /* !defined(__ASSEBMLY__) */
 
  #endif /* LINUX_KEXEC_H */

include/linux/libfdt.h +0 -0

index 90ed4ebfa692..75fb40aa013b 100644
@@ -5,4 +5,7 @@
  #include <linux/libfdt_env.h>
  #include "../../scripts/dtc/libfdt/libfdt.h"
 

Quoted 5 lines

include/linux/libfdt.h line 9

Quoted 2 lines

include/linux/libfdt.h +2 -0

+/* Common device tree properties */
+#define FDT_PROP_IMA_KEXEC_BUFFER   "linux,ima-kexec-buffer"

This is not part of libfdt. We generally don't do defines for DT strings.

Should I create a new header file for this or would you suggest using an existing one?

Quoted 319 lines · Lakshmi Ramasubramanian

On 11/4/20 2:28 PM, Rob Herring wrote:

Hi Rob,

Thanks for reviewing the patch.

Quoted 23 lines · Lakshmi Ramasubramanian

Quoted 22 lines

The functions 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.

remove_ima_buffer() and delete_fdt_mem_rsv() are used to remove the IMA log entry from the device tree and free the memory reserved for the log. These functions need to be defined even if the current kernel does not support carrying forward IMA log across kexec since the previous kernel could have supported that and therefore the current kernel needs to free the allocation.

Rename remove_ima_buffer() to remove_ima_kexec_buffer(). Define remove_ima_kexec_buffer() and delete_fdt_mem_rsv() in drivers/of/fdt.c. A later patch in this series will use these functions to free the allocation, if any, made by the previous kernel for ARM64.

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.

Quoted 7 lines

Quoted 4 lines

Co-developed-by Prakhar Srivastava <[email protected]>

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

Signed-off-by Lakshmi Ramasubramanian <[email protected]>

Reported-by kernel test robot <[email protected]> error: kernel/kexec_file_fdt.c:30: undefined reference to `fdt_num_mem_rsv'

This should be added for a commit fixing the reported problem. 0-day didn't report what this patch implements.

I'll remove that in the updated patch I'll post.

Quoted 221 lines

Quoted 221 lines

---
   arch/powerpc/include/asm/ima.h   |  10 +--
   arch/powerpc/include/asm/kexec.h |   1 -
   arch/powerpc/kexec/file_load.c   |  33 +---------
   arch/powerpc/kexec/ima.c         |  55 +++-------------
   drivers/of/fdt.c                 | 110 +++++++++++++++++++++++++++++++
   include/linux/kexec.h            |  24 +++++++
   include/linux/libfdt.h           |   3 +
   7 files changed, 149 insertions(+), 87 deletions(-)

arch/powerpc/include/asm/ima.h +3 -7

index ead488cf3981..6355a85a3289 100644
@@ -2,17 +2,13 @@
   #ifndef _ASM_POWERPC_IMA_H
   #define _ASM_POWERPC_IMA_H
 
+#include <linux/kexec.h>
+
   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 +18,7 @@ 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);
+    remove_ima_kexec_buffer(fdt, chosen_node);
      return 0;
   }
   #endif /* CONFIG_IMA_KEXEC */

arch/powerpc/include/asm/kexec.h +0 -1

index 55d6ede30c19..7c223031ecdd 100644
@@ -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;

arch/powerpc/kexec/file_load.c +1 -32

index 9a232bc36c8f..7a17655c530e 100644
@@ -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.

arch/powerpc/kexec/ima.c +8 -47

index 720e50e490b6..2b790230ea15 100644
@@ -11,6 +11,8 @@
   #include <linux/of.h>
   #include <linux/memblock.h>
   #include <linux/libfdt.h>
+#include <linux/ima.h>
+#include <asm/ima.h>
 
   static int get_addr_size_cells(int *addr_cells, int *size_cells)
   {

@@ -28,24 +30,6 @@ 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.

@@ -100,37 +84,14 @@ int ima_free_kexec_buffer(void)
 
   }
 
-/**
- * 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
    *
+ * @image: kimage struct to set IMA buffer data
+ * @load_addr: Starting address where IMA buffer is loaded at
+ * @size: Number of bytes in the IMA buffer
+ *
    * Architectures should use this function to pass on the IMA buffer
    * information to the next kernel.
    *

@@ -179,7 +140,7 @@ 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_kexec_buffer(fdt, chosen_node);
      if (!image->arch.ima_buffer_size)
              return 0;
 

@@ -201,7 +162,7 @@ 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;

drivers/of/fdt.c +1 -0

index 4602e467ca8b..d2e6f8ce0e42 100644
@@ -25,6 +25,7 @@
   #include <linux/serial_core.h>
   #include <linux/sysfs.h>
   #include <linux/random.h>
+#include <linux/kexec.h>
 
   #include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
   #include <asm/page.h>

@@ -1289,4 +1290,113 @@ static int __init of_fdt_raw_init(void)
   late_initcall(of_fdt_raw_init);
   #endif
 

Quoted 3 lines

drivers/of/fdt.c static int __init of_fdt_raw_init(void) · line 1293

Quoted 1 line

drivers/of/fdt.c +1 -0

+#ifdef CONFIG_HAVE_IMA_KEXEC

Can we avoid #ifdef and use IS_ENABLED() within the functions?

I can use IS_ENABLED() or move the functions to another C file and conditionally build based on the CONFIG.

Quoted 10 lines

Quoted 10 lines

drivers/of/fdt.c +9 -0

+/**
+ * do_get_kexec_buffer - Get address and size of IMA kexec buffer
+ *
+ * @prop: IMA kexec buffer node in the device tree
+ * @len: Size of the given device tree node property
+ * @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,

Quoted 8 lines

drivers/of/fdt.c static int __init of_fdt_raw_init(void) · line 1308

Quoted 6 lines

drivers/of/fdt.c +6 -0

+                    size_t *size)
+{
+    int addr_cells, size_cells;
+    struct device_node *root;
+
+    root = of_find_node_by_path("/");

The code in fdt.c operates on flat trees. This is an unflattened tree.

Would it be better if I move these functions to a new C file under "drivers/of"?

Quoted 17 lines

Quoted 4 lines

drivers/of/fdt.c +3 -0

+    if (!root)
+            return -EINVAL;
+

drivers/of/fdt.c static int __init of_fdt_raw_init(void) · line 1321

Quoted 10 lines

drivers/of/fdt.c +10 -0

+    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);

There's nothing in this function specific to 'kexec buffer'.

Quoted 5 lines

This interface is kind of broken. 'prop' could come from anywhere in the tree, but we always read the root address and size cells. Those only apply to immediate child node properties. And anything other than immediate root child nodes, there needs to be address translation.

I moved this function from arch/powerpc/kexec/ima.c to here so that it can be shared by ARM64 as well. Below is one of the usage of do_get_kexec_buffer().

          prop = of_get_property(of_chosen, "linux,ima-kexec-buffer", &len);
          if (!prop)
                  return -ENOENT;

Quoted 4 lines

          ret = do_get_kexec_buffer(prop, len, &tmp_addr, &tmp_size);

Is there a way to detect if the 'prop' is an immediate root child node or not so that we can handle it appropriately in this interface function?

Just don't split up the function.

Quoted 25 lines

Quoted 10 lines

drivers/of/fdt.c static int __init of_fdt_raw_init(void) · line 1328

Quoted 8 lines

drivers/of/fdt.c +7 -0

+
+    return 0;
+}
+
+/**
+ * remove_ima_kexec_buffer - remove the IMA buffer property and
+ *                       reservation from @fdt

IIRC, kerneldoc requires this to be one line.

I'll upate.

Quoted 12 lines

drivers/of/fdt.c static int __init of_fdt_raw_init(void) · line 1337

Quoted 10 lines

drivers/of/fdt.c +9 -0

+ *
+ * @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 remove_ima_kexec_buffer(void *fdt, int chosen_node)
+{

Can't this go in some common kexec code?

Quoted 3 lines

I'd considered moving this to "kernel", but Thiago suggested "drivers/of" is a better place. If you have suggestions for a better place, please let me know.

Humm, I guess drivers/of/ is fine, but it should be its own file. Also, there's nothing arch specific about handling bootargs, initrd, etc., so create a common function to handle all that. You can probably include allocating and copying the new fdt as part of that. Powerpc does kmalloc and arm64 does vmalloc for the new fdt. Is that a necessary difference?

Then the IMA handling can all be private to the new file?

Quoted 85 lines

Note that this function needs to be available even when CONFIG_IMA is not enabled. So I can't move it to "security/integrity/ima".

Quoted 80 lines

Quoted 70 lines

drivers/of/fdt.c +64 -0

+    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_debug("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_debug("Removed old IMA buffer reservation.\n");
+}
+#endif /* CONFIG_HAVE_IMA_KEXEC */
+
+#ifdef CONFIG_KEXEC_FILE
+/**
+ * delete_fdt_mem_rsv - delete memory reservation with given address and size
+ *
+ * @fdt: Flattened Device Tree to update
+ * @start: Starting address of the reservation to delete
+ * @size: Size of the 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)
+{
+    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_debug("Freed reserved memory at %lu of size %lu\n",
+                             start, size);
+                    return 0;
+            }
+    }
+
+    return -ENOENT;
+}
+#endif /* CONFIG_KEXEC_FILE */
+
   #endif /* CONFIG_OF_EARLY_FLATTREE */

include/linux/kexec.h +0 -0

index 9e93bef52968..6c6c6791a7ba 100644

include/linux/kexec.h static inline int kexec_crash_loaded(void) { return 0; } · line 410

Quoted 4 lines

include/linux/kexec.h +1 -0

@@ -407,6 +407,30 @@ static inline int kexec_crash_loaded(void) { return 0; }
   #define kexec_in_progress false
   #endif /* CONFIG_KEXEC_CORE */
 
+#if defined(CONFIG_OF_EARLY_FLATTREE) && defined(CONFIG_HAVE_IMA_KEXEC)

CONFIG_OF_EARLY_FLATTREE is wrong because that's all early boot (i.e. init section) functions.

If these functions are implemented in fdt.c, then this is the wrong header. But it's the implementation that should move.

Quoted 6 lines

If you think defining these functions in "drivers/of" is okay, I'll move them to a new C file in OF.

Would CONFIG_OF_FLATTREE be a better one to enable these ima kexec functions? "of_" and "fdt_" are the functions called by these ima kexec functions.

Yes.

Quoted 42 lines

Quoted 42 lines

Quoted 34 lines

include/linux/kexec.h +23 -0

+extern void remove_ima_kexec_buffer(void *fdt, int chosen_node);
+extern int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
+                           size_t *size);
+#else
+static inline void remove_ima_kexec_buffer(void *fdt, int chosen_node) {}
+static inline int do_get_kexec_buffer(const void *prop, int len,
+                                  unsigned long *addr, size_t *size)
+{
+    return -EOPNOTSUPP;
+}
+#endif /* CONFIG_OF_EARLY_FLATTREE && CONFIG_HAVE_IMA_KEXEC */
+
+#if defined(CONFIG_OF_EARLY_FLATTREE) && defined(CONFIG_KEXEC_FILE)
+extern int delete_fdt_mem_rsv(void *fdt, unsigned long start,
+                          unsigned long size);
+#else
+static inline int delete_fdt_mem_rsv(void *fdt, unsigned long start,
+                                 unsigned long size)
+{
+    return 0;
+}
+#endif /* CONFIG_OF_EARLY_FLATTREE && CONFIG_KEXEC_FILE */
+
   #endif /* !defined(__ASSEBMLY__) */
 
   #endif /* LINUX_KEXEC_H */

include/linux/libfdt.h +0 -0

index 90ed4ebfa692..75fb40aa013b 100644

include/linux/libfdt.h line 9

Quoted 5 lines

include/linux/libfdt.h +2 -0

@@ -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"

This is not part of libfdt. We generally don't do defines for DT strings.

Quoted 2 lines

Should I create a new header file for this or would you suggest using an existing one?

I'm suggesting no define at all. The string is already descriptive, so what do you gain with the define name? Nothing.

The functions ima_get_kexec_buffer() and ima_free_kexec_buffer(), 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 ima_get_kexec_buffer() and ima_free_kexec_buffer() to IMA subsystem. A later patch in this series will use these functions for carrying forward the IMA measurement log for ARM64.

With the above refactoring arch/powerpc/kexec/ima.c contains only functions used when CONFIG_IMA_KEXEC is enabled. Update Makefile in arch/powerpc/kexec to include arch/powerpc/kexec/ima.c only when CONFIG_IMA_KEXEC is enabled.

Co-developed-by Prakhar Srivastava <[email protected]>

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

Signed-off-by Lakshmi Ramasubramanian <[email protected]>

Quoted 14 lines

The functions ima_get_kexec_buffer() and ima_free_kexec_buffer(), 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 ima_get_kexec_buffer() and ima_free_kexec_buffer() to IMA subsystem. A later patch in this series will use these functions for carrying forward the IMA measurement log for ARM64.

With the above refactoring arch/powerpc/kexec/ima.c contains only functions used when CONFIG_IMA_KEXEC is enabled. Update Makefile in arch/powerpc/kexec to include arch/powerpc/kexec/ima.c only when CONFIG_IMA_KEXEC is enabled.

Quoted 3 lines

Co-developed-by Prakhar Srivastava <[email protected]>

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

Signed-off-by Lakshmi Ramasubramanian <[email protected]>

Similar comments to 1/4.
- Last line of first paragraph can be rephrased like " ... on kexec, do not contain architecture specific code, but are currently limited to powerpc."

- This patch should be limited to moving existing functions. Truncate the Subject line to "Move arch independent IMA kexec functions to ima_kexec.c."

- Don't refer to a later patch, but explain the purpose here. For example, "Move ... , making them accessible to other archs."

- The definition of "FDT_PROP_IMA_KEXEC_BUFFER" should be made as a separate, prepartory patch, prior to the existing 1/4. The resulting code being moved in this patch (and similarly for 1/4) will be exactly the same as the code being deleted.

On 11/3/20 6:55 AM, Mimi Zohar wrote:

Hi Mimi,

Quoted 16 lines · Lakshmi Ramasubramanian

Quoted 14 lines

The functions ima_get_kexec_buffer() and ima_free_kexec_buffer(), 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 ima_get_kexec_buffer() and ima_free_kexec_buffer() to IMA subsystem. A later patch in this series will use these functions for carrying forward the IMA measurement log for ARM64.

With the above refactoring arch/powerpc/kexec/ima.c contains only functions used when CONFIG_IMA_KEXEC is enabled. Update Makefile in arch/powerpc/kexec to include arch/powerpc/kexec/ima.c only when CONFIG_IMA_KEXEC is enabled.

Quoted 8 lines

Quoted 3 lines

Co-developed-by Prakhar Srivastava <[email protected]>

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

Signed-off-by Lakshmi Ramasubramanian <[email protected]>

Similar comments to 1/4.
- Last line of first paragraph can be rephrased like " ... on kexec, do not contain architecture specific code, but are currently limited to powerpc."

Sure.

Quoted 3 lines

- This patch should be limited to moving existing functions. Truncate the Subject line to "Move arch independent IMA kexec functions to ima_kexec.c."

Will do.

Quoted 2 lines

- Don't refer to a later patch, but explain the purpose here. For example, "Move ... , making them accessible to other archs."

Sure.

Quoted 4 lines

- The definition of "FDT_PROP_IMA_KEXEC_BUFFER" should be made as a separate, prepartory patch, prior to the existing 1/4. The resulting code being moved in this patch (and similarly for 1/4) will be exactly the same as the code being deleted.

Definition of FDT_PROP_IMA_KEXEC_BUFFER will be made as a preparatory patch as you'd mentioned in the comments for [PATCH 1/4].

Will split [PATCH 2/4] as listed below:

PATCH #1: Move ima_get_kexec_buffer() and ima_free_kexec_buffer() to IMA, along with deleting them in arch/powerpc/kexec/ima.c

Quoted 47 lines · Lakshmi Ramasubramanian

On 11/3/20 6:55 AM, Mimi Zohar wrote:

Hi Mimi,

Quoted 16 lines · Lakshmi Ramasubramanian

Quoted 14 lines

The functions ima_get_kexec_buffer() and ima_free_kexec_buffer(), 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 ima_get_kexec_buffer() and ima_free_kexec_buffer() to IMA subsystem. A later patch in this series will use these functions for carrying forward the IMA measurement log for ARM64.

With the above refactoring arch/powerpc/kexec/ima.c contains only functions used when CONFIG_IMA_KEXEC is enabled. Update Makefile in arch/powerpc/kexec to include arch/powerpc/kexec/ima.c only when CONFIG_IMA_KEXEC is enabled.

Quoted 8 lines

Quoted 3 lines

Co-developed-by Prakhar Srivastava <[email protected]>

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

Signed-off-by Lakshmi Ramasubramanian <[email protected]>

Similar comments to 1/4.
- Last line of first paragraph can be rephrased like " ... on kexec, do not contain architecture specific code, but are currently limited to powerpc."

Sure.

Quoted 3 lines

- This patch should be limited to moving existing functions. Truncate the Subject line to "Move arch independent IMA kexec functions to ima_kexec.c."

Will do.

Quoted 2 lines

- Don't refer to a later patch, but explain the purpose here. For example, "Move ... , making them accessible to other archs."

Sure.

Quoted 4 lines

- The definition of "FDT_PROP_IMA_KEXEC_BUFFER" should be made as a separate, prepartory patch, prior to the existing 1/4. The resulting code being moved in this patch (and similarly for 1/4) will be exactly the same as the code being deleted.

Definition of FDT_PROP_IMA_KEXEC_BUFFER will be made as a preparatory patch as you'd mentioned in the comments for [PATCH 1/4].

Quoted 4 lines

Will split [PATCH 2/4] as listed below:

PATCH #1: Move ima_get_kexec_buffer() and ima_free_kexec_buffer() to IMA, along with deleting them in arch/powerpc/kexec/ima.c

No, other than the comments above, this patch is fine. It moves ima_get_kexec_buffer() and ima_free_kexec_buffer() to ima_kexec.c.

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 patch series is based on
commit 598a597636f8 ("Merge tag 'afs-fixes-20201029' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs")
in https://github.com/torvalds/linux "master" branch.

Quoted 7 lines

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.

Nice, but you might want to tweak it a bit. This is just a suggestion. "A remote attestation service can verify a TPM quote based on the TPM event log, the IMA measurement list, and the TPM PCR data".

Quoted 5 lines

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.

The paragraphs above and below are redundant. The first paragraph already explained why carrying the measurement across kexec is needed. Perhaps drop the above paragraph.

Quoted 4 lines

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.

And invert these sentences, starting the paragraph with "Powerpc already" and ending with ARM64.

Quoted 7 lines

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 set moves ..."