diff options
| -rw-r--r-- | src/img4.c | 78 |
1 files changed, 69 insertions, 9 deletions
@@ -77,7 +77,65 @@ static unsigned char* asn1_create_element_header(unsigned char type, unsigned in *data_size = off; return *data; -} +} + +static unsigned int asn1_get_element(const unsigned char* data, unsigned char* type, unsigned char* size) +{ + unsigned int off = 0; + + if (!data) + return 0; + + if (type) + *type = data[off++]; + if (size) + *size = data[off++]; + + return off; +} + +static const unsigned char *asn1_find_element(unsigned int index, unsigned char type, const unsigned char* data) +{ + unsigned char el_type = 0; + unsigned char el_size = 0; + unsigned int off = 0; + + // verify data integrity + if (data[off++] != (ASN1_CONSTRUCTED | ASN1_SEQUENCE)) + return NULL; + + // check data size + switch (data[off++]) { + case 0x84: + off += 4; + break; + case 0x83: + off += 3; + break; + case 0x82: + off += 2; + break; + case 0x81: + off += 1; + break; + default: + break; + } + + // find the element we are searching + for (int i = 0; i <= index; i++) { + off += asn1_get_element(&data[off], &el_type, &el_size); + if (i == index) + break; + off += el_size; + } + + // check element type + if (el_type != type) + return NULL; + + return &data[off]; +} int img4_stitch_component(const char* component_name, const unsigned char* component_data, unsigned int component_size, const unsigned char* blob, unsigned int blob_size, unsigned char** img4_data, unsigned int *img4_size) { @@ -96,15 +154,17 @@ int img4_stitch_component(const char* component_name, const unsigned char* compo } info("Personalizing IMG4 component %s...\n", component_name); - /* first we need check if we have to change the tag for the given component */ - // FIXME: write proper ASN1 handling code for this - if (strcmp(component_name, "RestoreKernelCache") == 0) { - memcpy((char*)component_data+0xD, "rkrn", 4); - } else if (strcmp(component_name, "RestoreDeviceTree") == 0) { - memcpy((char*)component_data+0xD, "rdtr", 4); - } else if (strcmp(component_name, "RestoreSEP") == 0) { - memcpy((char*)component_data+0xD, "rsep", 4); + const void *tag = asn1_find_element(1, ASN1_IA5_STRING, component_data); + if (tag) { + debug("Tag found\n"); + if (strcmp(component_name, "RestoreKernelCache") == 0) { + memcpy((void*)tag, "rkrn", 4); + } else if (strcmp(component_name, "RestoreDeviceTree") == 0) { + memcpy((void*)tag, "rdtr", 4); + } else if (strcmp(component_name, "RestoreSEP") == 0) { + memcpy((void*)tag, "rsep", 4); + } } // create element header for the "IMG4" magic |