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images: Add automatic image crc generation for imd

PATCH In review Yunus Bas 3 participants 6 messages Dec 4, 2020 – Dec 8, 2020

Subsystems (2)
Arm i.MX and Layerscape Kbuild
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Yunus Bas

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#0 lore raw

PATCH 1/1 images: Add automatic image crc generation for imd

Since commit 9d12256bfcc6, the barebox IMD-header has an additional register space for CRC32 checksum. This is an important feature, since it allows us to verify the barebox image after flashing to the hardware.

This patch adds an optional feature for automatically generating the CRC32 checksum and writing it into IMD-section for all generated image-files. Additionally, the file 'barebox-imd-crc', containing the list of IMD outputs including the CRC32-value, will be generated under the images directory.

Signed-off-by Yunus Bas <[email protected]>
---
 common/Kconfig  | 11 +++++++++++
 images/Makefile | 16 ++++++++++++++--
 2 files changed, 25 insertions(+), 2 deletions(-)
common/Kconfig +11 -0
index 9b73aa845..a278cdbef 100644
@@ -697,6 +697,17 @@ config IMD
 	select CRC32
 	bool "barebox metadata support"
 
+config IMD_CRC_IMAGE
+	bool "crc32 checksum generation for IMD-header"
+	depends on IMD
+	help
+	  Enable this option for automatic generation and addition of the
+	  crc checksum to the Barebox ImageMetaData (IMD). Once enabled,
+	  this option uses the bareboximd-tool under the scripts directory
+	  to generate and set the crc checksums for all generated img-files.
+	  In addition, the file 'barebox-imd-crc' with a list of IMD's
+	  from the generated images will be created in the images-directory.
+
 config IMD_TARGET
 	bool "build bareboximd target tool"
 	depends on IMD
images/Makefile +14 -2
index b8899dcd2..f5a320bf6 100644
@@ -196,7 +196,12 @@ flash-link := $(obj)/../barebox-flash-image
 link-dest := $(if $(filter 1,$(words $(image-y))),$(image-y-path),multi-image-build)
 multi-image-build:
 
-images: $(image-y-path) $(flash-link) $(flash-list) FORCE
+# List of IMD's, including the filled crc reg, from the generated images
+ifdef CONFIG_IMD_CRC_IMAGE
+crc-gen := $(obj)/barebox-imd-crc
+endif
+
+images: $(image-y-path) $(flash-link) $(flash-list) $(crc-gen) FORCE
 	@echo "images built:"
 	@for i in $(image-y); do echo $$i; done
 

@@ -206,8 +211,15 @@ $(flash-link): $(link-dest) FORCE
 $(flash-list): $(image-y-path)
 	@for i in $^; do echo $$i; done > $@
 
+$(crc-gen): $(image-y-path)
+	@echo "generating and adding crc checksum to barebox images:"
+	@for i in $^; do \
+		echo "$$i:"; \
+		scripts/bareboximd -c $$i; \
+	done > $@
+
 clean-files := *.pbl *.pblb *.map start_*.imximg *.img barebox.z start_*.kwbimg \
 	start_*.kwbuartimg *.socfpgaimg *.mlo *.t20img *.t20img.cfg *.t30img \
 	*.t30img.cfg *.t124img *.t124img.cfg *.mlospi *.mlo *.mxsbs *.mxssd \
 	start_*.simximg start_*.usimximg *.zynqimg *.image
-clean-files += pbl.lds
+clean-files += pbl.lds barebox-imd-crc
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#1 lore raw

Hi Yunus,

Quoted 9 lines · Yunus Bas

Since commit 9d12256bfcc6, the barebox IMD-header has an additional register space for CRC32 checksum. This is an important feature, since it allows us to verify the barebox image after flashing to the hardware.

This patch adds an optional feature for automatically generating the CRC32 checksum and writing it into IMD-section for all generated image-files. Additionally, the file 'barebox-imd-crc', containing the list of IMD outputs including the CRC32-value, will be generated under the images directory.

It's not that easy unfortunately. Generating CRC IMD tags doesn't work for many image types. For example the i.MX28 images are all encrypted, so the bareboximd command won't find any valid tags in the binary. The signed i.MX6 HAB images could be added a CRC to, but doing that would invalidate the signature.
I'm afraid it's not possible to add a IMD crc to all images, we must carefully select the images we can actually do that.

Having said that, generating the crcs automatically would be really great and I have also thought about that. See the following series as a starting point. It's not complete though, because it generates the crcs also in HAB signed images.

Sascha

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#2 lore raw

PATCH 1/3 imd command: specify outfile for crc tag generation

Signed-off-by Sascha Hauer <[email protected]>
---
 commands/imd.c       |  2 +-
 common/imd.c         | 11 +++++------
 scripts/bareboximd.c |  2 +-
 3 files changed, 7 insertions(+), 8 deletions(-)
commands/imd.c +1 -1
index 9f7ac79f8f..5cb80db0f5 100644
@@ -33,7 +33,7 @@ BAREBOX_CMD_HELP_OPT ("-n <no>", "for tags with multiple strings only show strin
 BAREBOX_CMD_HELP_OPT ("-s VARNAME",  "set variable VARNAME instead of showing information")
 BAREBOX_CMD_HELP_OPT ("-v", "Be verbose")
 BAREBOX_CMD_HELP_OPT ("-V",  "Verify checksum of FILE")
-BAREBOX_CMD_HELP_OPT ("-c", "Create checksum for FILE and write it to the crc32 tag.")
+BAREBOX_CMD_HELP_OPT ("-c OUTFILE", "Create checksum for FILE and write it to the crc32 tag.")
 BAREBOX_CMD_HELP_TEXT("")
 BAREBOX_CMD_HELP_TEXT("Without options all information available is printed. Valid types are:")
 BAREBOX_CMD_HELP_TEXT("release, build, model, of_compatible")
common/imd.c +5 -6
index 4aca8ea78f..044f04bcdd 100644
@@ -435,15 +435,14 @@ int imd_command(int argc, char *argv[])
 	size_t size;
 	uint32_t type = IMD_TYPE_INVALID;
 	const struct imd_header *imd_start, *imd;
-	const char *filename;
+	const char *filename, *checksumfile = NULL;
 	const char *variable_name = NULL;
 	char *str;
-	uint32_t checksum = 0;
 	uint32_t verify = 0;
 
 	imd_command_verbose = 0;
 
-	while ((opt = getopt(argc, argv, "vt:s:n:cV")) > 0) {
+	while ((opt = getopt(argc, argv, "vt:s:n:c:V")) > 0) {
 		switch(opt) {
 		case 't':
 			type = imd_name_to_type(optarg);

@@ -462,7 +461,7 @@ int imd_command(int argc, char *argv[])
 			strno = simple_strtoul(optarg, NULL, 0);
 			break;
 		case 'c':
-			checksum = 1;
+			checksumfile = optarg;
 			break;
 		case 'V':
 			verify = 1;

@@ -489,8 +488,8 @@ int imd_command(int argc, char *argv[])
 		goto out;
 	}
 
-	if (checksum) {
-		ret = imd_write_crc32(buf, imd_start, filename, size);
+	if (checksumfile) {
+		ret = imd_write_crc32(buf, imd_start, checksumfile, size);
 		goto out;
 	}
scripts/bareboximd.c +1 -1
index 0500e01cc2..1ae01e43d3 100644
@@ -163,7 +163,7 @@ static void usage(const char *prgname)
 "-n <no>      for tags with multiple strings only show string <no>\n"
 "-v           Be verbose\n"
 "-V           Verify checksum of FILE\n"
-"-c           Create checksum for FILE and write it to the crc32 tag\n"
+"-c OUTFILE   Create checksum for FILE and write it to the crc32 tag\n"
 "\n"
 "Without options all information available is printed. Valid types are:\n"
 "release, build, model, of_compatible\n",
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#3 lore raw

PATCH 2/3 kbuild: Add command to generate the crc for the IMD crc tag

Signed-off-by Sascha Hauer <[email protected]>
---
 scripts/Makefile.lib | 11 +++++++++++
 1 file changed, 11 insertions(+)
scripts/Makefile.lib +11 -0
index 2844d29be6..060dad5087 100644
@@ -448,6 +448,17 @@ cmd_lz4 = (cat $(filter-out FORCE,$^) | \
 %.lz4: %
 	$(call if_changed,lz4)
 
+ifdef CONFIG_IMD
+quiet_cmd_gen_imd_crc = GENCRC $@
+cmd_gen_imd_crc = scripts/bareboximd -c $@ $<
+else
+quiet_cmd_gen_imd_crc =
+cmd_gen_imd_crc = true
+endif
+
+%.imdcrc: %
+	$(call if_changed,gen_imd_crc)
+
 # comp_copy
 # ---------------------------------------------------------------------------
 # Wrapper which only copies a file, but compatible to the compression
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#4 lore raw

PATCH 3/3 images: i.MX: fill in crc in IMD crc tags

In reply to Sascha Hauer

FIXME: This also generates crcs in the signed images which invalidates the signature.

Signed-off-by Sascha Hauer <[email protected]>
---
 images/Makefile.imx | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
images/Makefile.imx +1 -1
index 514db326bb..808c7a13e8 100644
@@ -26,7 +26,7 @@ endef
 .SECONDEXPANSION:
 define imx_image_rule
 $(eval
-$$(obj)/%.$(strip $(1)): $$(obj)/% $$$$(CFG_%.imximg) FORCE
+$$(obj)/%.$(strip $(1)): $$(obj)/%.imdcrc $$$$(CFG_%.imximg) FORCE
 	$$(call if_changed,imx_image,$$(CFG_$$(patsubst %.$(strip $(1)),%.imximg,$$(@F))),$(strip $(2)))
 )
 endef
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author
#5 lore raw
In reply to Sascha Hauer

Hi Sascha,

Am 07.12.20 um 10:28 schrieb Sascha Hauer:

Quoted 20 lines

Hi Yunus,

Quoted 9 lines · Yunus Bas

Since commit 9d12256bfcc6, the barebox IMD-header has an additional register space for CRC32 checksum. This is an important feature, since it allows us to verify the barebox image after flashing to the hardware.

This patch adds an optional feature for automatically generating the CRC32 checksum and writing it into IMD-section for all generated image-files. Additionally, the file 'barebox-imd-crc', containing the list of IMD outputs including the CRC32-value, will be generated under the images directory.

It's not that easy unfortunately. Generating CRC IMD tags doesn't work for many image types. For example the i.MX28 images are all encrypted, so the bareboximd command won't find any valid tags in the binary. The signed i.MX6 HAB images could be added a CRC to, but doing that would invalidate the signature.
I'm afraid it's not possible to add a IMD crc to all images, we must carefully select the images we can actually do that.

Quoted 7 lines

Having said that, generating the crcs automatically would be really great and I have also thought about that. See the following series as a starting point. It's not complete though, because it generates the crcs also in HAB signed images.

Sascha

Thank you for the reply and sorry that I have not thought about signed images, which is obvious.

From your patches I can see, that you have changed the bareboximd behaviour and also added additional imdcrc files. Personally, I wouldn't have gone that far, but it looks like your approach is the cleaner solution. I will consider your patches and search for a solution on top of them.

Mit freundlichen Grüßen

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Yunus Bas
- Software Entwicklung -
Tel.: +49 6131 92 21 0
[email protected]
<http://www.phytec.de/>


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