[PATCH 05/16] tools: Improve comments in signing functions
Simon Glass
sjg at chromium.org
Fri Nov 12 20:28:06 CET 2021
Add some more comments to explain what is going on in the signing
functions. Fix two repeated typos.
Signed-off-by: Simon Glass <sjg at chromium.org>
---
include/image.h | 2 +-
tools/fdt_host.h | 8 ++++
tools/image-host.c | 98 +++++++++++++++++++++++++++++++++++-----------
3 files changed, 85 insertions(+), 23 deletions(-)
diff --git a/include/image.h b/include/image.h
index fd662e74b41..533c23e2002 100644
--- a/include/image.h
+++ b/include/image.h
@@ -1025,7 +1025,7 @@ int fit_cipher_data(const char *keydir, void *keydest, void *fit,
* fit_add_verification_data() - add verification data to FIT image nodes
*
* @keydir: Directory containing keys
- * @kwydest: FDT blob to write public key information to
+ * @kwydest: FDT blob to write public key information to (NULL if none)
* @fit: Pointer to the FIT format image header
* @comment: Comment to add to signature nodes
* @require_keys: Mark all keys as 'required'
diff --git a/tools/fdt_host.h b/tools/fdt_host.h
index 15c07c7a96e..bc42306c9e5 100644
--- a/tools/fdt_host.h
+++ b/tools/fdt_host.h
@@ -27,6 +27,14 @@
*/
int fdt_remove_unused_strings(const void *old, void *new);
+/**
+ * fit_check_sign() - Check a signature in a FIT
+ *
+ * @fit: FIT to check
+ * @key: Key FDT blob to check against
+ * @fit_uname_config: Name of configuration to check (NULL for default)
+ * @return 0 if OK, -ve if signature failed
+ */
int fit_check_sign(const void *fit, const void *key,
const char *fit_uname_config);
diff --git a/tools/image-host.c b/tools/image-host.c
index a6b0a944205..73d35f3eee3 100644
--- a/tools/image-host.c
+++ b/tools/image-host.c
@@ -48,10 +48,10 @@ static int fit_set_hash_value(void *fit, int noffset, uint8_t *value,
* fit_image_process_hash - Process a single subnode of the images/ node
*
* Check each subnode and process accordingly. For hash nodes we generate
- * a hash of the supplised data and store it in the node.
+ * a hash of the supplied data and store it in the node.
*
* @fit: pointer to the FIT format image header
- * @image_name: name of image being processes (used to display errors)
+ * @image_name: name of image being processed (used to display errors)
* @noffset: subnode offset
* @data: data to process
* @size: size of data in bytes
@@ -197,12 +197,12 @@ static int fit_image_setup_sig(struct image_sign_info *info,
* fit_image_process_sig- Process a single subnode of the images/ node
*
* Check each subnode and process accordingly. For signature nodes we
- * generate a signed hash of the supplised data and store it in the node.
+ * generate a signed hash of the supplied data and store it in the node.
*
* @keydir: Directory containing keys to use for signing
- * @keydest: Destination FDT blob to write public keys into
+ * @keydest: Destination FDT blob to write public keys into (NULL if none)
* @fit: pointer to the FIT format image header
- * @image_name: name of image being processes (used to display errors)
+ * @image_name: name of image being processed (used to display errors)
* @noffset: subnode offset
* @data: data to process
* @size: size of data in bytes
@@ -685,14 +685,14 @@ static int strlist_add(struct strlist *list, const char *str)
return 0;
}
-static const char *fit_config_get_image_list(void *fit, int noffset,
- int *lenp, int *allow_missingp)
+static const char *fit_config_get_image_list(const void *fit, int noffset,
+ int *lenp, int *allow_missingp)
{
static const char default_list[] = FIT_KERNEL_PROP "\0"
FIT_FDT_PROP;
const char *prop;
- /* If there is an "image" property, use that */
+ /* If there is an "sign-image" property, use that */
prop = fdt_getprop(fit, noffset, "sign-images", lenp);
if (prop) {
*allow_missingp = 0;
@@ -706,8 +706,24 @@ static const char *fit_config_get_image_list(void *fit, int noffset,
return default_list;
}
-static int fit_config_add_hash(void *fit, const char *conf_name, const char *sig_name,
- struct strlist *node_inc, const char *iname, int image_noffset)
+/**
+ * fit_config_add_hash() - Add a list of nodes to hash for an image
+ *
+ * This adds a list of paths to image nodes (as referred to by a particular
+ * offset) that need to be hashed, to protect a configuration
+ *
+ * @fit: Pointer to the FIT format image header
+ * @image_noffset: Offset of image to process (e.g. /images/kernel-1)
+ * @node_inc: List of nodes to add to
+ * @conf_name Configuration-node name, child of /configurations node (only
+ * used for error messages)
+ * @sig_name Signature-node name (only used for error messages)
+ * @iname: Name of image being processed (e.g. "kernel-1" (only used
+ * for error messages)
+ */
+static int fit_config_add_hash(const void *fit, int image_noffset,
+ struct strlist *node_inc, const char *conf_name,
+ const char *sig_name, const char *iname)
{
char name[200], path[200];
int noffset;
@@ -777,7 +793,21 @@ err_path:
return -ENOENT;
}
-static int fit_config_get_hash_list(void *fit, int conf_noffset,
+/**
+ * fit_config_get_hash_list() - Get the regions to sign
+ *
+ * This calculates a list of nodes to hash for this particular configuration,
+ * returning it as a string list (struct strlist, not a devicetree string list)
+ *
+ * @fit: Pointer to the FIT format image header
+ * @conf_noffset: Offset of configuration node to sign (child of
+ * /configurations node)
+ * @sig_offset: Offset of signature node containing info about how to sign it
+ * (child of 'signatures' node)
+ * @return 0 if OK, -ENOENT if an image referred to by the configuration cannot
+ * be found, -ENOMSG if ther were no images in the configuration
+ */
+static int fit_config_get_hash_list(const void *fit, int conf_noffset,
int sig_offset, struct strlist *node_inc)
{
int allow_missing;
@@ -828,9 +858,8 @@ static int fit_config_get_hash_list(void *fit, int conf_noffset,
return -ENOENT;
}
- ret = fit_config_add_hash(fit, conf_name,
- sig_name, node_inc,
- iname, image_noffset);
+ ret = fit_config_add_hash(fit, image_noffset, node_inc,
+ conf_name, sig_name, iname);
if (ret < 0)
return ret;
@@ -852,9 +881,32 @@ err_mem:
return -ENOMEM;
}
-static int fit_config_get_data(void *fit, int conf_noffset, int noffset,
- struct image_region **regionp, int *region_countp,
- char **region_propp, int *region_proplen)
+/**
+ * fit_config_get_regions() - Get the regions to sign
+ *
+ * This calculates a list of node to hash for this particular configuration,
+ * then finds which regions of the devicetree they correspond to.
+ *
+ * @fit: Pointer to the FIT format image header
+ * @conf_noffset: Offset of configuration node to sign (child of
+ * /configurations node)
+ * @sig_offset: Offset of signature node containing info about how to sign it
+ * (child of 'signatures' node)
+ * @regionp: Returns list of regions that need to be hashed (allocated; must be
+ * freed by the caller)
+ * @region_count: Returns number of regions
+ * @region_propp: Returns string-list property containing the list of nodes
+ * that correspond to the regions. Each entry is a full path to the node.
+ * This is in devicetree format, i.e. a \0 between each string. This is
+ * allocated and must be freed by the caller.
+ * @region_proplen: Returns length of *@@region_propp in bytes
+ * @return 0 if OK, -ENOMEM if out of memory, -EIO if the regions to hash could
+ * not be found, -EINVAL if no registers were found to hash
+ */
+static int fit_config_get_regions(const void *fit, int conf_noffset,
+ int sig_offset, struct image_region **regionp,
+ int *region_countp, char **region_propp,
+ int *region_proplen)
{
char * const exc_prop[] = {"data"};
struct strlist node_inc;
@@ -867,11 +919,12 @@ static int fit_config_get_data(void *fit, int conf_noffset, int noffset,
int ret, len;
conf_name = fit_get_name(fit, conf_noffset, NULL);
- sig_name = fit_get_name(fit, noffset, NULL);
+ sig_name = fit_get_name(fit, sig_offset, NULL);
debug("%s: conf='%s', sig='%s'\n", __func__, conf_name, sig_name);
/* Get a list of nodes we want to hash */
- ret = fit_config_get_hash_list(fit, conf_noffset, noffset, &node_inc);
+ ret = fit_config_get_hash_list(fit, conf_noffset, sig_offset,
+ &node_inc);
if (ret)
return ret;
@@ -925,7 +978,7 @@ static int fit_config_get_data(void *fit, int conf_noffset, int noffset,
}
static int fit_config_process_sig(const char *keydir, const char *keyfile,
- void *keydest, void *fit, const char *conf_name,
+ void *keydest, void *fit, const char *conf_name,
int conf_noffset, int noffset, const char *comment,
int require_keys, const char *engine_id, const char *cmdname)
{
@@ -940,8 +993,9 @@ static int fit_config_process_sig(const char *keydir, const char *keyfile,
int ret;
node_name = fit_get_name(fit, noffset, NULL);
- if (fit_config_get_data(fit, conf_noffset, noffset, ®ion,
- ®ion_count, ®ion_prop, ®ion_proplen))
+ if (fit_config_get_regions(fit, conf_noffset, noffset, ®ion,
+ ®ion_count, ®ion_prop,
+ ®ion_proplen))
return -1;
if (fit_image_setup_sig(&info, keydir, keyfile, fit, conf_name, noffset,
--
2.34.0.rc1.387.gb447b232ab-goog
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