From 70e6bcc43f541fbcb8e878dba8299e8e30943bcd Mon Sep 17 00:00:00 2001 From: Simon Glass Date: Fri, 12 Nov 2021 12:28:06 -0700 Subject: tools: Improve comments in signing functions Add some more comments to explain what is going on in the signing functions. Fix two repeated typos. Signed-off-by: Simon Glass --- tools/image-host.c | 98 ++++++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 76 insertions(+), 22 deletions(-) (limited to 'tools/image-host.c') diff --git a/tools/image-host.c b/tools/image-host.c index f86e1fb..a5d47a4 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 @@ -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, ®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, -- cgit v1.1