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tools: Improve comments in signing functions

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Add some more comments to explain what is going on in the signing
functions. Fix two repeated typos.

Signed-off-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Simon Glass 2021-11-12 12:28:06 -07:00
parent 7ae46c3579
commit 70e6bcc43f
3 changed files with 85 additions and 23 deletions
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2
include/image.h
View file

@ -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'

8
tools/fdt_host.h
View file

@ -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);

98
tools/image-host.c
View file

@ -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
@ -200,12 +200,12 @@ 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
@ -689,14 +689,14 @@ 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;
@ -710,8 +710,24 @@ 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;
@ -781,7 +797,21 @@ 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;
@ -832,9 +862,8 @@ 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;
@ -856,9 +885,32 @@ 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;
@ -871,11 +923,12 @@ 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;
@ -929,7 +982,7 @@ 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,
const char *algo_name)
@ -945,8 +998,9 @@ 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, &region,
&region_count, &region_prop, &region_proplen))
if (fit_config_get_regions(fit, conf_noffset, noffset, &region,
&region_count, &region_prop,
&region_proplen))
return -1;
if (fit_image_setup_sig(&info, keydir, keyfile, fit, conf_name, noffset,