| /* Capstone Disassembly Engine */ |
| /* BPF Backend by david942j <david942j@gmail.com>, 2019 */ |
| |
| #include <string.h> |
| |
| #include "BPFConstants.h" |
| #include "BPFMapping.h" |
| #include "../../Mapping.h" |
| #include "../../utils.h" |
| |
| #ifndef CAPSTONE_DIET |
| static const name_map group_name_maps[] = { |
| { BPF_GRP_INVALID, NULL }, |
| |
| { BPF_GRP_LOAD, "load" }, |
| { BPF_GRP_STORE, "store" }, |
| { BPF_GRP_ALU, "alu" }, |
| { BPF_GRP_JUMP, "jump" }, |
| { BPF_GRP_CALL, "call" }, |
| { BPF_GRP_RETURN, "return" }, |
| { BPF_GRP_MISC, "misc" }, |
| }; |
| #endif |
| |
| const char *BPF_group_name(csh handle, unsigned int id) |
| { |
| #ifndef CAPSTONE_DIET |
| return id2name(group_name_maps, ARR_SIZE(group_name_maps), id); |
| #else |
| return NULL; |
| #endif |
| } |
| |
| #ifndef CAPSTONE_DIET |
| static const name_map insn_name_maps[BPF_INS_ENDING] = { |
| { BPF_INS_INVALID, NULL }, |
| |
| { BPF_INS_ADD, "add" }, |
| { BPF_INS_SUB, "sub" }, |
| { BPF_INS_MUL, "mul" }, |
| { BPF_INS_DIV, "div" }, |
| { BPF_INS_OR, "or" }, |
| { BPF_INS_AND, "and" }, |
| { BPF_INS_LSH, "lsh" }, |
| { BPF_INS_RSH, "rsh" }, |
| { BPF_INS_NEG, "neg" }, |
| { BPF_INS_MOD, "mod" }, |
| { BPF_INS_XOR, "xor" }, |
| { BPF_INS_MOV, "mov" }, |
| { BPF_INS_ARSH, "arsh" }, |
| |
| { BPF_INS_ADD64, "add64" }, |
| { BPF_INS_SUB64, "sub64" }, |
| { BPF_INS_MUL64, "mul64" }, |
| { BPF_INS_DIV64, "div64" }, |
| { BPF_INS_OR64, "or64" }, |
| { BPF_INS_AND64, "and64" }, |
| { BPF_INS_LSH64, "lsh64" }, |
| { BPF_INS_RSH64, "rsh64" }, |
| { BPF_INS_NEG64, "neg64" }, |
| { BPF_INS_MOD64, "mod64" }, |
| { BPF_INS_XOR64, "xor64" }, |
| { BPF_INS_MOV64, "mov64" }, |
| { BPF_INS_ARSH64, "arsh64" }, |
| |
| { BPF_INS_LE16, "le16" }, |
| { BPF_INS_LE32, "le32" }, |
| { BPF_INS_LE64, "le64" }, |
| { BPF_INS_BE16, "be16" }, |
| { BPF_INS_BE32, "be32" }, |
| { BPF_INS_BE64, "be64" }, |
| { BPF_INS_BSWAP16, "bswap16" }, |
| { BPF_INS_BSWAP32, "bswap32" }, |
| { BPF_INS_BSWAP64, "bswap64" }, |
| |
| { BPF_INS_LDW, "ldw" }, |
| { BPF_INS_LDH, "ldh" }, |
| { BPF_INS_LDB, "ldb" }, |
| { BPF_INS_LDDW, "lddw" }, |
| { BPF_INS_LDXW, "ldxw" }, |
| { BPF_INS_LDXH, "ldxh" }, |
| { BPF_INS_LDXB, "ldxb" }, |
| { BPF_INS_LDXDW, "ldxdw" }, |
| |
| { BPF_INS_STW, "stw" }, |
| { BPF_INS_STH, "sth" }, |
| { BPF_INS_STB, "stb" }, |
| { BPF_INS_STDW, "stdw" }, |
| { BPF_INS_STXW, "stxw" }, |
| { BPF_INS_STXH, "stxh" }, |
| { BPF_INS_STXB, "stxb" }, |
| { BPF_INS_STXDW, "stxdw" }, |
| { BPF_INS_XADDW, "xaddw" }, |
| { BPF_INS_XADDDW, "xadddw" }, |
| |
| { BPF_INS_JMP, "jmp" }, |
| { BPF_INS_JEQ, "jeq" }, |
| { BPF_INS_JGT, "jgt" }, |
| { BPF_INS_JGE, "jge" }, |
| { BPF_INS_JSET, "jset" }, |
| { BPF_INS_JNE, "jne" }, |
| { BPF_INS_JSGT, "jsgt" }, |
| { BPF_INS_JSGE, "jsge" }, |
| { BPF_INS_CALL, "call" }, |
| { BPF_INS_CALLX, "callx" }, |
| { BPF_INS_EXIT, "exit" }, |
| { BPF_INS_JLT, "jlt" }, |
| { BPF_INS_JLE, "jle" }, |
| { BPF_INS_JSLT, "jslt" }, |
| { BPF_INS_JSLE, "jsle" }, |
| |
| { BPF_INS_RET, "ret" }, |
| |
| { BPF_INS_TAX, "tax" }, |
| { BPF_INS_TXA, "txa" }, |
| }; |
| #endif |
| |
| const char *BPF_insn_name(csh handle, unsigned int id) |
| { |
| #ifndef CAPSTONE_DIET |
| /* We have some special cases because 'ld' in cBPF is equivalent to 'ldw' |
| * in eBPF, and we don't want to see 'ldw' appears in cBPF mode. |
| */ |
| if (!EBPF_MODE(handle)) { |
| switch (id) { |
| case BPF_INS_LD: return "ld"; |
| case BPF_INS_LDX: return "ldx"; |
| case BPF_INS_ST: return "st"; |
| case BPF_INS_STX: return "stx"; |
| } |
| } |
| return id2name(insn_name_maps, ARR_SIZE(insn_name_maps), id); |
| #else |
| return NULL; |
| #endif |
| } |
| |
| const char *BPF_reg_name(csh handle, unsigned int reg) |
| { |
| #ifndef CAPSTONE_DIET |
| if (EBPF_MODE(handle)) { |
| if (reg < BPF_REG_R0 || reg > BPF_REG_R10) |
| return NULL; |
| static const char reg_names[11][4] = { |
| "r0", "r1", "r2", "r3", "r4", |
| "r5", "r6", "r7", "r8", "r9", |
| "r10" |
| }; |
| return reg_names[reg - BPF_REG_R0]; |
| } |
| |
| /* cBPF mode */ |
| if (reg == BPF_REG_A) |
| return "a"; |
| else if (reg == BPF_REG_X) |
| return "x"; |
| else |
| return NULL; |
| #else |
| return NULL; |
| #endif |
| } |
| |
| static bpf_insn op2insn_ld(unsigned opcode) |
| { |
| #define CASE(c) case BPF_SIZE_##c: \ |
| if (BPF_CLASS(opcode) == BPF_CLASS_LD) \ |
| return BPF_INS_LD##c; \ |
| else \ |
| return BPF_INS_LDX##c; |
| |
| switch (BPF_SIZE(opcode)) { |
| CASE(W); |
| CASE(H); |
| CASE(B); |
| CASE(DW); |
| } |
| #undef CASE |
| |
| return BPF_INS_INVALID; |
| } |
| |
| static bpf_insn op2insn_st(unsigned opcode) |
| { |
| /* |
| * - BPF_STX | BPF_XADD | BPF_{W,DW} |
| * - BPF_ST* | BPF_MEM | BPF_{W,H,B,DW} |
| */ |
| |
| if (opcode == (BPF_CLASS_STX | BPF_MODE_XADD | BPF_SIZE_W)) |
| return BPF_INS_XADDW; |
| if (opcode == (BPF_CLASS_STX | BPF_MODE_XADD | BPF_SIZE_DW)) |
| return BPF_INS_XADDDW; |
| |
| /* should be BPF_MEM */ |
| #define CASE(c) case BPF_SIZE_##c: \ |
| if (BPF_CLASS(opcode) == BPF_CLASS_ST) \ |
| return BPF_INS_ST##c; \ |
| else \ |
| return BPF_INS_STX##c; |
| switch (BPF_SIZE(opcode)) { |
| CASE(W); |
| CASE(H); |
| CASE(B); |
| CASE(DW); |
| } |
| #undef CASE |
| |
| return BPF_INS_INVALID; |
| } |
| |
| static bpf_insn op2insn_alu(unsigned opcode) |
| { |
| /* Endian is a special case */ |
| if (BPF_OP(opcode) == BPF_ALU_END) { |
| if (BPF_CLASS(opcode) == BPF_CLASS_ALU64) { |
| switch (opcode ^ BPF_CLASS_ALU64 ^ BPF_ALU_END ^ BPF_SRC_LITTLE) { |
| case (16 << 4): |
| return BPF_INS_BSWAP16; |
| case (32 << 4): |
| return BPF_INS_BSWAP32; |
| case (64 << 4): |
| return BPF_INS_BSWAP64; |
| default: |
| return BPF_INS_INVALID; |
| } |
| } |
| |
| switch (opcode ^ BPF_CLASS_ALU ^ BPF_ALU_END) { |
| case BPF_SRC_LITTLE | (16 << 4): |
| return BPF_INS_LE16; |
| case BPF_SRC_LITTLE | (32 << 4): |
| return BPF_INS_LE32; |
| case BPF_SRC_LITTLE | (64 << 4): |
| return BPF_INS_LE64; |
| case BPF_SRC_BIG | (16 << 4): |
| return BPF_INS_BE16; |
| case BPF_SRC_BIG | (32 << 4): |
| return BPF_INS_BE32; |
| case BPF_SRC_BIG | (64 << 4): |
| return BPF_INS_BE64; |
| } |
| return BPF_INS_INVALID; |
| } |
| |
| #define CASE(c) case BPF_ALU_##c: \ |
| if (BPF_CLASS(opcode) == BPF_CLASS_ALU) \ |
| return BPF_INS_##c; \ |
| else \ |
| return BPF_INS_##c##64; |
| |
| switch (BPF_OP(opcode)) { |
| CASE(ADD); |
| CASE(SUB); |
| CASE(MUL); |
| CASE(DIV); |
| CASE(OR); |
| CASE(AND); |
| CASE(LSH); |
| CASE(RSH); |
| CASE(NEG); |
| CASE(MOD); |
| CASE(XOR); |
| CASE(MOV); |
| CASE(ARSH); |
| } |
| #undef CASE |
| |
| return BPF_INS_INVALID; |
| } |
| |
| static bpf_insn op2insn_jmp(unsigned opcode) |
| { |
| if (opcode == (BPF_CLASS_JMP | BPF_JUMP_CALL | BPF_SRC_X)) { |
| return BPF_INS_CALLX; |
| } |
| |
| #define CASE(c) case BPF_JUMP_##c: return BPF_INS_##c |
| switch (BPF_OP(opcode)) { |
| case BPF_JUMP_JA: |
| return BPF_INS_JMP; |
| CASE(JEQ); |
| CASE(JGT); |
| CASE(JGE); |
| CASE(JSET); |
| CASE(JNE); |
| CASE(JSGT); |
| CASE(JSGE); |
| CASE(CALL); |
| CASE(EXIT); |
| CASE(JLT); |
| CASE(JLE); |
| CASE(JSLT); |
| CASE(JSLE); |
| } |
| #undef CASE |
| |
| return BPF_INS_INVALID; |
| } |
| |
| #ifndef CAPSTONE_DIET |
| static void update_regs_access(cs_struct *ud, cs_detail *detail, |
| bpf_insn insn_id, unsigned int opcode) |
| { |
| if (insn_id == BPF_INS_INVALID) |
| return; |
| #define PUSH_READ(r) do { \ |
| detail->regs_read[detail->regs_read_count] = r; \ |
| detail->regs_read_count++; \ |
| } while (0) |
| #define PUSH_WRITE(r) do { \ |
| detail->regs_write[detail->regs_write_count] = r; \ |
| detail->regs_write_count++; \ |
| } while (0) |
| /* |
| * In eBPF mode, only these instructions have implicit registers access: |
| * - legacy ld{w,h,b,dw} * // w: r0 |
| * - exit // r: r0 |
| */ |
| if (EBPF_MODE(ud)) { |
| switch (insn_id) { |
| default: |
| break; |
| case BPF_INS_LDW: |
| case BPF_INS_LDH: |
| case BPF_INS_LDB: |
| case BPF_INS_LDDW: |
| if (BPF_MODE(opcode) == BPF_MODE_ABS || BPF_MODE(opcode) == BPF_MODE_IND) { |
| PUSH_WRITE(BPF_REG_R0); |
| } |
| break; |
| case BPF_INS_EXIT: |
| PUSH_READ(BPF_REG_R0); |
| break; |
| } |
| return; |
| } |
| |
| /* cBPF mode */ |
| switch (BPF_CLASS(opcode)) { |
| default: |
| break; |
| case BPF_CLASS_LD: |
| PUSH_WRITE(BPF_REG_A); |
| break; |
| case BPF_CLASS_LDX: |
| PUSH_WRITE(BPF_REG_X); |
| break; |
| case BPF_CLASS_ST: |
| PUSH_READ(BPF_REG_A); |
| break; |
| case BPF_CLASS_STX: |
| PUSH_READ(BPF_REG_X); |
| break; |
| case BPF_CLASS_ALU: |
| PUSH_READ(BPF_REG_A); |
| PUSH_WRITE(BPF_REG_A); |
| break; |
| case BPF_CLASS_JMP: |
| if (insn_id != BPF_INS_JMP) // except the unconditional jump |
| PUSH_READ(BPF_REG_A); |
| break; |
| /* case BPF_CLASS_RET: */ |
| case BPF_CLASS_MISC: |
| if (insn_id == BPF_INS_TAX) { |
| PUSH_READ(BPF_REG_A); |
| PUSH_WRITE(BPF_REG_X); |
| } |
| else { |
| PUSH_READ(BPF_REG_X); |
| PUSH_WRITE(BPF_REG_A); |
| } |
| break; |
| } |
| } |
| #endif |
| |
| /* |
| * 1. Convert opcode(id) to BPF_INS_* |
| * 2. Set regs_read/regs_write/groups |
| */ |
| void BPF_get_insn_id(cs_struct *ud, cs_insn *insn, unsigned int opcode) |
| { |
| // No need to care the mode (cBPF or eBPF) since all checks has be done in |
| // BPF_getInstruction, we can simply map opcode to BPF_INS_*. |
| bpf_insn id = BPF_INS_INVALID; |
| #ifndef CAPSTONE_DIET |
| cs_detail *detail; |
| bpf_insn_group grp; |
| |
| detail = insn->detail; |
| #define PUSH_GROUP(grp) do { \ |
| if (detail) { \ |
| detail->groups[detail->groups_count] = grp; \ |
| detail->groups_count++; \ |
| } \ |
| } while(0) |
| #else |
| #define PUSH_GROUP(grp) do {} while(0) |
| #endif |
| |
| switch (BPF_CLASS(opcode)) { |
| default: // will never happen |
| break; |
| case BPF_CLASS_LD: |
| case BPF_CLASS_LDX: |
| id = op2insn_ld(opcode); |
| PUSH_GROUP(BPF_GRP_LOAD); |
| break; |
| case BPF_CLASS_ST: |
| case BPF_CLASS_STX: |
| id = op2insn_st(opcode); |
| PUSH_GROUP(BPF_GRP_STORE); |
| break; |
| case BPF_CLASS_ALU: |
| id = op2insn_alu(opcode); |
| PUSH_GROUP(BPF_GRP_ALU); |
| break; |
| case BPF_CLASS_JMP: |
| id = op2insn_jmp(opcode); |
| #ifndef CAPSTONE_DIET |
| grp = BPF_GRP_JUMP; |
| if (id == BPF_INS_CALL || id == BPF_INS_CALLX) |
| grp = BPF_GRP_CALL; |
| else if (id == BPF_INS_EXIT) |
| grp = BPF_GRP_RETURN; |
| PUSH_GROUP(grp); |
| #endif |
| break; |
| case BPF_CLASS_RET: |
| id = BPF_INS_RET; |
| PUSH_GROUP(BPF_GRP_RETURN); |
| break; |
| // BPF_CLASS_MISC and BPF_CLASS_ALU64 have exactly same value |
| case BPF_CLASS_MISC: |
| /* case BPF_CLASS_ALU64: */ |
| if (EBPF_MODE(ud)) { |
| // ALU64 in eBPF |
| id = op2insn_alu(opcode); |
| PUSH_GROUP(BPF_GRP_ALU); |
| } |
| else { |
| if (BPF_MISCOP(opcode) == BPF_MISCOP_TXA) |
| id = BPF_INS_TXA; |
| else |
| id = BPF_INS_TAX; |
| PUSH_GROUP(BPF_GRP_MISC); |
| } |
| break; |
| } |
| |
| insn->id = id; |
| #undef PUSH_GROUP |
| |
| #ifndef CAPSTONE_DIET |
| if (detail) { |
| update_regs_access(ud, detail, id, opcode); |
| } |
| #endif |
| } |
| |
| static void sort_and_uniq(cs_regs arr, uint8_t n, uint8_t *new_n) |
| { |
| /* arr is always a tiny (usually n < 3) array, |
| * a simple O(n^2) sort is efficient enough. */ |
| int i; |
| int j; |
| int iMin; |
| int tmp; |
| |
| /* a modified selection sort for sorting and making unique */ |
| for (j = 0; j < n; j++) { |
| /* arr[iMin] will be min(arr[j .. n-1]) */ |
| iMin = j; |
| for (i = j + 1; i < n; i++) { |
| if (arr[i] < arr[iMin]) |
| iMin = i; |
| } |
| if (j != 0 && arr[iMin] == arr[j - 1]) { // duplicate ele found |
| arr[iMin] = arr[n - 1]; |
| --n; |
| } |
| else { |
| tmp = arr[iMin]; |
| arr[iMin] = arr[j]; |
| arr[j] = tmp; |
| } |
| } |
| |
| *new_n = n; |
| } |
| void BPF_reg_access(const cs_insn *insn, |
| cs_regs regs_read, uint8_t *regs_read_count, |
| cs_regs regs_write, uint8_t *regs_write_count) |
| { |
| unsigned i; |
| uint8_t read_count, write_count; |
| const cs_bpf *bpf = &(insn->detail->bpf); |
| |
| read_count = insn->detail->regs_read_count; |
| write_count = insn->detail->regs_write_count; |
| |
| // implicit registers |
| memcpy(regs_read, insn->detail->regs_read, read_count * sizeof(insn->detail->regs_read[0])); |
| memcpy(regs_write, insn->detail->regs_write, write_count * sizeof(insn->detail->regs_write[0])); |
| |
| for (i = 0; i < bpf->op_count; i++) { |
| const cs_bpf_op *op = &(bpf->operands[i]); |
| switch (op->type) { |
| default: |
| break; |
| case BPF_OP_REG: |
| if (op->access & CS_AC_READ) { |
| regs_read[read_count] = op->reg; |
| read_count++; |
| } |
| if (op->access & CS_AC_WRITE) { |
| regs_write[write_count] = op->reg; |
| write_count++; |
| } |
| break; |
| case BPF_OP_MEM: |
| if (op->mem.base != BPF_REG_INVALID) { |
| regs_read[read_count] = op->mem.base; |
| read_count++; |
| } |
| break; |
| } |
| } |
| |
| sort_and_uniq(regs_read, read_count, regs_read_count); |
| sort_and_uniq(regs_write, write_count, regs_write_count); |
| } |