imd: add support for checksum generation/verification

Add a new imd type "checksum". This type consists of the CRC32 checksum
of the whole barebox image minus the checksum itself.
The checksum can be written to the imd field with the bareboximd host-tool.
It can be verified with said tool or with "imd" on the target.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 151 insertions, 1 deletions

diff --git a/common/imd.c b/common/imd.c
index e0dab69644..9be07fef74 100644
--- a/common/imd.c
+++ b/common/imd.c
@@ -22,6 +22,7 @@
 #include <getopt.h>
 #include <malloc.h>
 #include <fs.h>
+#include <crc.h>
 
 #ifndef CONFIG_CMD_IMD
 int imd_command_setenv(const char *variable_name, const char *value)
@@ -167,6 +168,9 @@ static struct imd_type_names imd_types[] = {
 	}, {
 		.type = IMD_TYPE_OF_COMPATIBLE,
 		.name = "of_compatible",
+	}, {
+		.type = IMD_TYPE_CRC32,
+		.name = "crc32",
 	},
 };
 
@@ -257,6 +261,23 @@ char *imd_concat_strings(const struct imd_header *imd)
 }
 
 /**
+ * imd_uint32_flags - get uint32 flags
+ * @imd: The IMD entry
+ *
+ * This function returns the flags in @imd.
+ *
+ * Return: A pointer to the flags or NULL if the entry is not uint32.
+ */
+static uint32_t *imd_crc32_flags(const struct imd_header *imd) {
+	char *p = (char *)(imd + 1);
+
+	if (!imd_is_crc32(imd_read_type(imd)))
+		return NULL;
+
+	return (uint32_t *)(p + sizeof(uint32_t));
+}
+
+/**
  * imd_get_param - get a parameter
  * @imd: The IMD entry
  * @name: The name of the parameter.
@@ -287,6 +308,118 @@ const char *imd_get_param(const struct imd_header *imd, const char *name)
 	return NULL;
 }
 
+static int imd_calculate_crc32(void *input, const struct imd_header *imd_start,
+			       struct imd_header **imd_crc, uint32_t *crc,
+			       size_t size)
+{
+	const struct imd_header *imd;
+	int length;
+	int end_ofs = (char *)imd_start - (char *)input + sizeof(char) * 8;
+
+	/* search the checksum imd token */
+	imd_for_each(imd_start, imd) {
+		length = imd_read_length(imd);
+		length = ALIGN(length, 4);
+		length += sizeof(struct imd_header);
+
+		if (imd_read_type(imd) == IMD_TYPE_CRC32) {
+			*imd_crc = (struct imd_header *)imd;
+			debug("Found crc token at %d\n", end_ofs);
+			break;
+		}
+
+		end_ofs += length;
+	}
+
+	/*
+	 * Calculate checksum from start of input up to the checksum.
+	 * The checksum and the flags field in the imd_entry_crc32 entry are
+	 * modified after the checksum is calculated. Therefore skip them here
+	 * or the checksum will become invalid once it is written to the
+	 * checksum tag.
+	 */
+	length = sizeof(struct imd_header);
+	end_ofs += length;
+
+	*crc = crc32(*crc, input, end_ofs);
+	debug("Calculated checksum from %d to %d: 0x%08x\n", 0, end_ofs, *crc);
+
+	/* move past the checksum data and flags field */
+	end_ofs += sizeof(uint32_t) + sizeof(char);
+	input += end_ofs;
+
+	*crc = crc32(*crc, input, size - end_ofs);
+	debug("Calculated checksum from %d to %d: 0x%08x\n", end_ofs,
+	      end_ofs + (size - end_ofs), *crc);
+
+	return 0;
+}
+
+static int imd_write_crc32(void *buf, const struct imd_header *imd_start,
+			   const char *filename, size_t size)
+{
+	struct imd_header *imd_crc;
+	uint32_t crc = 0;
+
+	imd_calculate_crc32(buf, imd_start, &imd_crc, &crc, size);
+	debug("Calculated crc: 0x%08x\n", crc);
+
+	if (!imd_crc) {
+		debug("No tag of type 0x%08x found\n", IMD_TYPE_CRC32);
+
+		return -ENODATA;
+	} else {
+		uint32_t *p = (uint32_t *)(imd_crc + 1);
+
+		if (*p != crc) {
+			uint32_t *flags = imd_crc32_flags(imd_crc);
+			*flags |= IMD_CRC32_FLAG_TAG_VALID;
+			debug("Update crc token from 0x%08x to 0x%08x (flags 0x%08x)\n", *p, crc, *flags);
+			*p = crc;
+
+			write_file(filename, buf, size);
+		}
+	}
+
+	return 0;
+};
+
+int imd_verify_crc32(void *buf, size_t size)
+{
+	const struct imd_header *imd_start;
+	struct imd_header *imd_crc;
+	uint32_t crc = 0;
+
+	imd_start = imd_get(buf, size);
+	if (IS_ERR(imd_start))
+		return PTR_ERR(imd_start);
+
+	imd_calculate_crc32(buf, imd_start, &imd_crc, &crc, size);
+	debug("Calculated crc: 0x%08x\n", crc);
+
+	if (!imd_crc) {
+		debug("No tag of type 0x%08x found\n", IMD_TYPE_CRC32);
+
+		return -ENOENT;
+	} else {
+		uint32_t *p = (uint32_t *)(imd_crc + 1);
+		uint32_t *flags = imd_crc32_flags(imd_crc);
+
+		if (*p != crc && imd_crc32_is_valid(*flags)) {
+			eprintf("CRC: image corrupted. Found checksum 0x%08x instead of 0x%08x\n",
+			       *p, crc);
+			return -EILSEQ;
+		} else if (*p != crc && !imd_crc32_is_valid(*flags)) {
+			printf("CRC: is invalid, but the checksum tag is not enabled\n");
+			return -EINVAL;
+		} else {
+			printf("CRC: valid\n");
+		}
+	}
+
+	return 0;
+};
+
 int imd_command_verbose;
 
 int imd_command(int argc, char *argv[])
@@ -299,10 +432,12 @@ int imd_command(int argc, char *argv[])
 	const char *filename;
 	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:")) > 0) {
+	while ((opt = getopt(argc, argv, "vt:s:n:cV")) > 0) {
 		switch(opt) {
 		case 't':
 			type = imd_name_to_type(optarg);
@@ -320,6 +455,12 @@ int imd_command(int argc, char *argv[])
 		case 'n':
 			strno = simple_strtoul(optarg, NULL, 0);
 			break;
+		case 'c':
+			checksum = 1;
+			break;
+		case 'V':
+			verify = 1;
+			break;
 		default:
 			return -ENOSYS;
 		}
@@ -342,6 +483,11 @@ int imd_command(int argc, char *argv[])
 		goto out;
 	}
 
+	if (checksum)
+		imd_write_crc32(buf, imd_start, filename, size);
+	if (verify)
+		imd_verify_crc32(buf, size);
+
 	if (type == IMD_TYPE_INVALID) {
 		imd_for_each(imd_start, imd) {
 			uint32_t type = imd_read_type(imd);
@@ -350,6 +496,10 @@ int imd_command(int argc, char *argv[])
 				str = imd_concat_strings(imd);
 
 				printf("%s: %s\n", imd_type_to_name(type), str);
+			} else if (imd_is_crc32(type)) {
+				uint32_t *p = (uint32_t *)(imd + 1);
+
+				printf("%s: 0x%08x\n", imd_type_to_name(type), *p);
 			} else {
 				debug("Unknown tag 0x%08x\n", type);
 			}