path: root/view/kernelcache/core/transformers/libimg4/img4.c

/*
 * pongoOS - https://checkra.in
 *
 * Copyright (C) 2021 checkra1n team
 *
 * This file is part of pongoOS.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 */
#include <stdlib.h>
#include <stddef.h>
#include "img4.h"

// ==================== ==================== ==================== Data ==================== ==================== ====================

const DERItemSpec DERImg4ItemSpecs[] =
        {
                {0 * sizeof(DERItem), ASN1_IA5_STRING, 0}, // IMG4
                {1 * sizeof(DERItem), ASN1_CONSTR_SEQUENCE, DER_DEC_SAVE_DER | DER_ENC_WRITE_DER}, // Payload
                {2 * sizeof(DERItem), ASN1_CONSTR_CONT | 0, DER_DEC_OPTIONAL}, // Manifest
                {3 * sizeof(DERItem), ASN1_CONSTR_CONT | 1, DER_DEC_OPTIONAL}, // RestoreInfo
        };
const DERItemSpec DERImg4PayloadItemSpecs[] =
        {
                {offsetof(Img4Payload, magic),       ASN1_IA5_STRING,   0}, // IM4P
                {offsetof(Img4Payload, type),        ASN1_IA5_STRING,   0}, // Type
                {offsetof(Img4Payload, version),     ASN1_IA5_STRING,   0}, // Version
                {offsetof(Img4Payload, payload),     ASN1_OCTET_STRING, 0}, // Payload
                {offsetof(Img4Payload, keybag),      ASN1_OCTET_STRING,    DER_DEC_OPTIONAL}, // Keybag
                {offsetof(Img4Payload, compression), ASN1_CONSTR_SEQUENCE, DER_DEC_OPTIONAL}, // Compression
        };
const DERItemSpec DERImg4ManifestItemSpecs[] =
        {
                {offsetof(Img4Manifest, magic),        ASN1_IA5_STRING,      0}, // IM4M
                {offsetof(Img4Manifest, zero),         ASN1_INTEGER,         0}, // 0
                {offsetof(Img4Manifest, properties),   ASN1_CONSTR_SET,
                        DER_DEC_SAVE_DER | DER_ENC_WRITE_DER}, // Properties
                {offsetof(Img4Manifest, signature),    ASN1_OCTET_STRING,    0}, // Signature
                {offsetof(Img4Manifest, certificates), ASN1_CONSTR_SEQUENCE, 0}, // Certificates
        };
const DERItemSpec DERImg4RestoreInfoItemSpecs[] =
        {
                {offsetof(Img4RestoreInfo, magic), ASN1_IA5_STRING, 0}, // IM4R
                {offsetof(Img4RestoreInfo, nonce), ASN1_CONSTR_SET, 0}, // Nonce
        };
const DERItemSpec DERImg4NonceItemSpecs[] =
        {
                {0 * sizeof(DERItem), ASN1_IA5_STRING,   0}, // BNCN
                {1 * sizeof(DERItem), ASN1_OCTET_STRING, 0}, // Nonce
        };
const DERItemSpec DERImg4CompressionItemSpecs[] =
        {
                {0 * sizeof(DERItem), ASN1_INTEGER, 0},
                {1 * sizeof(DERItem), ASN1_INTEGER, 0},
        };

// ==================== ==================== ==================== Code ==================== ==================== ====================

DERReturn DERImg4DecodeFindInSequence(DERByte *nextItem, DERByte *end, DERTag tag, DERItem *out) {
    DERDecodedInfo decoded;
    DERSequence seq = {nextItem, end};
    do {
        DERReturn ret = DERDecodeSeqNext(&seq, &decoded);
        if (ret != DR_Success) {
            return ret;
        }
    } while (decoded.tag != tag);
    *out = decoded.content;
    return DR_Success;
}

DERReturn DERImg4DecodeContentFindItemWithTag(const DERItem *der, DERTag tag, DERItem *out) {
    DERSequence seq;
    DERReturn ret = DERDecodeSeqContentInit(der, &seq);
    if (ret != DR_Success) {
        return ret;
    }
    return DERImg4DecodeFindInSequence(seq.nextItem, seq.end, tag, out);
}

DERReturn DERImg4DecodeTagCompare(const DERItem *der, uint32_t name) {
    if (der->length < 4) {
        return -1;
    }
    if (der->length > 4) {
        return 1;
    }
    uint32_t value;
    if (DERParseInteger(der, &value) != DR_Success) {
        return -2;
    }
    if (value < name) {
        return -1;
    }
    if (value > name) {
        return 1;
    }
    return 0;
}

DERReturn DERImg4Decode(const DERItem *der, DERItem *items) {
    DERReturn ret;
    DERDecodedInfo decoded;
    if (!der || !items) {
        return DR_ParamErr;
    }
    ret = DERDecodeItem(der, &decoded);
    if (ret != DR_Success) {
        return ret;
    }
    if (decoded.tag != ASN1_CONSTR_SEQUENCE) {
        return DR_UnexpectedTag;
    }
    if (der->data + der->length != decoded.content.data + decoded.content.length) {
        return DR_BufOverflow;
    }
    ret = DERParseSequenceContent(&decoded.content, sizeof(DERImg4ItemSpecs) / sizeof(DERImg4ItemSpecs[0]),
                                  DERImg4ItemSpecs, items, 0);
    if (ret != DR_Success) {
        return ret;
    }
    if (DERImg4DecodeTagCompare(&items[0], 'IMG4') != 0) {
        return DR_UnexpectedTag;
    }
    return DR_Success;
}
DERReturn DERImg4DecodePayload(const DERItem *der, Img4Payload *payload) {
    if (!der || !payload) {
        return DR_ParamErr;
    }
    DERReturn ret = DERParseSequence(der, sizeof(DERImg4PayloadItemSpecs) / sizeof(DERImg4PayloadItemSpecs[0]),
                                     DERImg4PayloadItemSpecs, payload, 0);
    if (ret != DR_Success) {
        return ret;
    }
    if (DERImg4DecodeTagCompare(&payload->magic, 'IM4P') != 0) {
        return DR_UnexpectedTag;
    }
    if (!payload->compression.data) {
        return DR_Success;
    }
    uint32_t val = -1;

    DERItem items[2];
    ret = DERParseSequenceContent(&payload->compression,
                                  sizeof(DERImg4CompressionItemSpecs) / sizeof(DERImg4CompressionItemSpecs[0]),
                                  DERImg4CompressionItemSpecs, items, 0);
    if (ret != DR_Success) {
        return ret;
    }
    ret = DERParseInteger(&items[0], &val);
    if (ret != DR_Success) {
        return ret;
    }
    if (val >= 2) {
        return DR_ParamErr;
    }
    return DR_Success;
}

DERReturn DERImg4DecodeManifest(const DERItem *der, Img4Manifest *manifest) {
    if (!der || !manifest) {
        return DR_ParamErr;
    }
    if (!der->data || !der->length) {
        return DR_Success;
    }
    DERReturn ret = DERParseSequence(der, sizeof(DERImg4ManifestItemSpecs) / sizeof(DERImg4ManifestItemSpecs[0]),
                                     DERImg4ManifestItemSpecs, manifest, 0);
    if (ret != DR_Success) {
        return ret;
    }
    if (DERImg4DecodeTagCompare(&manifest->magic, 'IM4M') != 0) {
        return DR_UnexpectedTag;
    }
    uint32_t zero;
    ret = DERParseInteger(&manifest->zero, &zero);
    if (ret != DR_Success) {
        return ret;
    }
    if (zero != 0) {
        return DR_UnexpectedTag;
    }
    return DR_Success;
}

DERReturn DERImg4DecodeRestoreInfo(const DERItem *der, Img4RestoreInfo *restoreInfo) {
    if (!der) {
        return DR_Success;
    }
    if (!restoreInfo) {
        return DR_ParamErr;
    }
    if (!der->data || !der->length) {
        return DR_Success;
    }
    DERReturn ret = DERParseSequence(der, sizeof(DERImg4RestoreInfoItemSpecs) / sizeof(DERImg4RestoreInfoItemSpecs[0]),
                                     DERImg4RestoreInfoItemSpecs, restoreInfo, 0);
    if (ret != DR_Success) {
        return ret;
    }
    if (DERImg4DecodeTagCompare(&restoreInfo->magic, 'IM4R') != 0) {
        return DR_UnexpectedTag;
    }
    return DR_Success;
}

DERReturn DERImg4DecodeFindProperty(const DERItem *der, DERTag ktag, DERTag vtag, Img4Property *prop) {
    DERItem key;
    DERReturn ret = DERImg4DecodeContentFindItemWithTag(der, ktag, &key);
    if (ret != DR_Success) {
        return ret;
    }
    DERItemSpec spec[] =
            {
                    {0 * sizeof(Img4Property), ASN1_IA5_STRING, 0},
                    {1 * sizeof(Img4Property), vtag,            0},
            };
    ret = DERParseSequence(&key, sizeof(spec) / sizeof(DERItemSpec), spec, prop, 0);
    if (ret != DR_Success) {
        return ret;
    }
    uint32_t tag;
    ret = DERParseInteger(&prop[0].content, &tag);
    if (ret != DR_Success) {
        return ret;
    }
    if ((ASN1_CONSTR_PRIVATE | tag) != ktag) {
        return DR_UnexpectedTag;
    }
    prop[0].tag = ASN1_CONSTR_PRIVATE | ktag;
    prop[1].tag = vtag;
    return DR_Success;
}

DERReturn Img4DecodeGetPayload(const Img4 *img4, DERItem *item) {
    if (!img4 || !item) {
        return DR_ParamErr;
    }
    if (!img4->payload.payload.data || !img4->payload.payload.length) {
        return DR_EndOfSequence;
    }
    *item = img4->payload.payload;
    return DR_Success;
}

DERReturn Img4DecodeGetPayloadType(const Img4 *img4, uint32_t *type) {
    if (!img4 || !type) {
        return DR_ParamErr;
    }
    if (!img4->payload.payload.data || !img4->payload.payload.length) {
        return DR_EndOfSequence;
    }
    return DERParseInteger(&img4->payload.type, type);
}

DERReturn Img4DecodeGetPayloadKeybag(const Img4 *img4, DERItem *kbag) {
    if (!img4 || !kbag) {
        return DR_ParamErr;
    }
    if (!img4->payload.payload.data || !img4->payload.payload.length) {
        return DR_EndOfSequence;
    }
    *kbag = img4->payload.keybag;
    return DR_Success;
}

DERReturn Img4DecodeInit(const DERByte *data, DERSize length, Img4 *img4) {
    DERReturn ret;
    if (!data || !img4) {
        return DR_ParamErr;
    }
    DERItem der = {.data = (DERByte *) data, .length = length};
    DERItem items[4] = {0};
	memset(img4, 0, sizeof(Img4));
    ret = DERImg4Decode(&der, items);
    if (ret != DR_Success) {
        return ret;
    }
    ret = DERImg4DecodePayload(&items[1], &img4->payload);
    if (ret != DR_Success) {
        return ret;
    }
    ret = DERImg4DecodeManifest(&items[2], &img4->manifest);
    if (ret != DR_Success) {
        return ret;
    }
    ret = DERImg4DecodeRestoreInfo(&items[3], &img4->restoreInfo);
    if (ret != DR_Success) {
        return ret;
    }
    img4->payloadRaw = items[1];
    img4->manifestRaw = items[2];
    return DR_Success;
}

DERReturn Img4Encode(DERItem *der, const DERItem *items) {
    return Img4EncodeSequence(ASN1_CONSTR_SEQUENCE, items, sizeof(DERImg4ItemSpecs) / sizeof(DERImg4ItemSpecs[0]),
                              DERImg4ItemSpecs, der);
}

DERReturn Img4EncodeRestoreInfo(DERItem *der, void *bytes, size_t len) {
    Img4RestoreInfo restoreInfo =
            {
                    .magic = {.data = (DERByte *) "IM4R", .length = 4},
            };
    DERItem bncn;
    DERItem items[] =
            {
                    {.data = (DERByte *) "BNCN", .length = 4},
                    {.data = bytes, .length = len},
            };
    DERReturn ret = Img4EncodeSequence(ASN1_CONSTR_SEQUENCE, items,
                                       sizeof(DERImg4NonceItemSpecs) / sizeof(DERImg4NonceItemSpecs[0]),
                                       DERImg4NonceItemSpecs, &bncn);
    if (ret == DR_Success) {
        DERSize inOutLen = 20 + bncn.length;
        DERByte *buf = malloc(inOutLen);
        if (!buf) {
            ret = -1;
        } else {
            ret = DEREncodeItem(ASN1_CONSTR_PRIVATE | 'BNCN', bncn.length, bncn.data, buf, &inOutLen);
            if (ret == DR_Success) {
                restoreInfo.nonce.data = buf;
                restoreInfo.nonce.length = inOutLen;
                ret = Img4EncodeSequence(ASN1_CONSTR_SEQUENCE, &restoreInfo,
                                         sizeof(DERImg4RestoreInfoItemSpecs) / sizeof(DERImg4RestoreInfoItemSpecs[0]),
                                         DERImg4RestoreInfoItemSpecs, der);
            }
            free(buf);
        }
        free(bncn.data);
    }
    return ret;
}

DERReturn
Img4EncodeSequence(DERTag tag, const void *src, DERShort numItems, const DERItemSpec *itemSpecs, DERItem *der) {
    if (!tag || !src || !numItems || !itemSpecs || !der) {
        return DR_ParamErr;
    }
    DERSize inOutLen = 20;
    for (DERShort i = 0; i < numItems; ++i) {
        const DERItemSpec *spec = &itemSpecs[i];
        const DERItem *item = (const DERItem *) ((uintptr_t) src + spec->offset);
        if (spec->options & DER_ENC_WRITE_DER) {
            inOutLen += item->length;
        } else if (item->length == 0 && (spec->options & DER_DEC_OPTIONAL)) {
            // Skip
        } else {
            inOutLen += item->length + 20; /* 1+9 tag, 1+8 size, 1 null pad */
        }
    }
    DERByte *buf = malloc(inOutLen);
    if (!buf) {
        return -1;
    }
    DERReturn ret = DEREncodeSequence(tag, src, numItems, itemSpecs, buf, &inOutLen);
    if (ret == DR_Success) {
        der->data = buf;
        der->length = inOutLen;
    } else {
        free(buf);
    }
    return ret;
}