asm_java.c

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// SPDX-FileCopyrightText: 2021 deroad <wargio@libero.it>
// SPDX-License-Identifier: LGPL-3.0-only
 
#include <rz_types.h>
#include <rz_util.h>
#include <rz_lib.h>
#include <rz_asm.h>
#include <rz_core.h>
 
#include "../arch/java/jvm.h"
#include "../arch/java/assembler.h"
 
typedef struct java_analysis_context_t {
    LookupSwitch ls;
    TableSwitch ts;
    ut16 switchop;
    ut64 pc;
    ut64 last;
    ut32 count;
} JavaAsmContext;
 
static void update_context(JavaAsmContext *ctx) {
    ctx->count++;
    if (ctx->switchop == BYTECODE_AA_TABLESWITCH && ctx->count > ctx->ts.length) {
        ctx->switchop = BYTECODE_00_NOP;
    } else if (ctx->switchop == BYTECODE_AB_LOOKUPSWITCH && ctx->count > ctx->ls.npairs) {
        ctx->switchop = BYTECODE_00_NOP;
    }
}
 
static int java_disassemble(RzAsm *a, RzAsmOp *op, const ut8 *buf, int len) {
    JavaAsmContext *ctx = (JavaAsmContext *)a->plugin_data;
    rz_strbuf_set(&op->buf_asm, "invalid");
 
    if (a->pc < ctx->last) {
        ctx->switchop = BYTECODE_00_NOP;
    }
    ctx->last = a->pc;
    switch (ctx->switchop) {
    case BYTECODE_AA_TABLESWITCH: {
        if (len < 4) {
            RZ_LOG_ERROR("[!] java_analysis: no enough data for lookupswitch case.\n");
            return -1;
        }
        op->size = 4;
        ut64 jump = ctx->pc + rz_read_be32(buf);
        rz_strbuf_setf(&op->buf_asm, "case %d: goto 0x%" PFMT64x, ctx->count + ctx->ts.low, jump);
        update_context(ctx);
        return op->size;
    }
    case BYTECODE_AB_LOOKUPSWITCH: {
        if (len < 8) {
            RZ_LOG_ERROR("[!] java_analysis: no enough data for lookupswitch case.\n");
            return -1;
        }
        op->size = 8;
        st32 number = (st32)rz_read_be32(buf);
        ut64 jump = ctx->pc + rz_read_at_be32(buf, 4);
        rz_strbuf_setf(&op->buf_asm, "case %d: goto 0x%" PFMT64x, number, jump);
        update_context(ctx);
        return op->size;
    }
    default:
        break;
    }
 
    JavaVM vm = { 0 };
    Bytecode bc = { 0 };
 
    rz_strbuf_set(&op->buf_asm, "invalid");
 
    ut64 section = a->pc;
    if (a->binb.bin) {
        const RzBinSection *sec = a->binb.get_vsect_at(a->binb.bin, a->pc);
        if (sec) {
            section = sec->paddr;
        }
    }
 
    if (!jvm_init(&vm, buf, len, a->pc, section)) {
        RZ_LOG_ERROR("[!] java_disassemble: bad or invalid data.\n");
        return -1;
    }
    op->size = 1;
    if (jvm_fetch(&vm, &bc)) {
        op->size = bc.size;
        bytecode_snprint(&op->buf_asm, &bc);
        if (bc.opcode == BYTECODE_AA_TABLESWITCH) {
            ctx->count = 0;
            ctx->switchop = BYTECODE_AA_TABLESWITCH;
            ctx->ts = *((TableSwitch *)bc.extra);
            ctx->pc = a->pc;
        } else if (bc.opcode == BYTECODE_AB_LOOKUPSWITCH) {
            ctx->count = 0;
            ctx->switchop = BYTECODE_AB_LOOKUPSWITCH;
            ctx->ls = *((LookupSwitch *)bc.extra);
            ctx->pc = a->pc;
        }
        bytecode_clean(&bc);
    } else {
        RZ_LOG_ERROR("[!] java_disassemble: jvm fetch failed.\n");
        return -1;
    }
    return op->size;
}
 
static bool java_init(void **user) {
    JavaAsmContext *ctx = RZ_NEW0(JavaAsmContext);
    if (!ctx) {
        return false;
    }
    *user = ctx;
    return true;
}
 
static bool java_fini(void *user) {
    if (!user) {
        return false;
    }
    JavaAsmContext *ctx = (JavaAsmContext *)user;
    free(ctx);
    return true;
}
 
static int java_assemble(RzAsm *a, RzAsmOp *ao, const char *str) {
    ut8 buffer[128];
    st32 written = 0;
    st32 slen = strlen(str);
 
    if (!java_assembler(str, slen, buffer, sizeof(buffer), a->pc, &written)) {
        return -1;
    }
 
    rz_strbuf_setbin(&ao->buf, (const ut8 *)&buffer, written);
    return written;
}
 
RzAsmPlugin rz_asm_plugin_java = {
    .name = "java",
    .desc = "Java bytecode disassembler",
    .arch = "java",
    .license = "LGPL-3",
    .author = "deroad",
    .bits = 32,
    .endian = RZ_SYS_ENDIAN_BIG,
    .init = java_init,
    .fini = java_fini,
    .disassemble = &java_disassemble,
    .assemble = &java_assemble,
};
 
#ifndef RZ_PLUGIN_INCORE
RZ_API RzLibStruct rizin_plugin = {
    .type = RZ_LIB_TYPE_ASM,
    .data = &rz_asm_plugin_java,
    .version = RZ_VERSION
};
#endif