/src/capstonenext/arch/BPF/BPFDisassembler.c

Source (jump to first uncovered line)
/* Capstone Disassembly Engine */
/* BPF Backend by david942j <david942j@gmail.com>, 2019 */

#ifdef CAPSTONE_HAS_BPF

#include <string.h>
#include <stddef.h> // offsetof macro

#include "BPFConstants.h"
#include "BPFDisassembler.h"
#include "BPFMapping.h"
#include "../../cs_priv.h"

static uint16_t read_u16(cs_struct *ud, const uint8_t *code)
{
  if (MODE_IS_BIG_ENDIAN(ud->mode))
    return (((uint16_t)code[0] << 8) | code[1]);
  else
    return (((uint16_t)code[1] << 8) | code[0]);
}

static uint32_t read_u32(cs_struct *ud, const uint8_t *code)
{
  if (MODE_IS_BIG_ENDIAN(ud->mode))
    return ((uint32_t)read_u16(ud, code) << 16) | read_u16(ud, code + 2);
  else
    return ((uint32_t)read_u16(ud, code + 2) << 16) | read_u16(ud, code);
}

///< Malloc bpf_internal, also checks if code_len is large enough.
static bpf_internal *alloc_bpf_internal(size_t code_len)
{
  bpf_internal *bpf;

  if (code_len < 8)
    return NULL;
  bpf = cs_mem_malloc(sizeof(bpf_internal));
  if (bpf == NULL)
    return NULL;
  /* default value */
  bpf->insn_size = 8;
  return bpf;
}

///< Fetch a cBPF structure from code
static bpf_internal* fetch_cbpf(cs_struct *ud, const uint8_t *code,
    size_t code_len)
{
  bpf_internal *bpf;

  bpf = alloc_bpf_internal(code_len);
  if (bpf == NULL)
    return NULL;

  bpf->op = read_u16(ud, code);
  bpf->jt = code[2];
  bpf->jf = code[3];
  bpf->k = read_u32(ud, code + 4);
  return bpf;
}

///< Fetch an eBPF structure from code
static bpf_internal* fetch_ebpf(cs_struct *ud, const uint8_t *code,
    size_t code_len)
{
  bpf_internal *bpf;

  bpf = alloc_bpf_internal(code_len);
  if (bpf == NULL)
    return NULL;

  bpf->op = (uint16_t)code[0];
  bpf->dst = code[1] & 0xf;
  bpf->src = (code[1] & 0xf0) >> 4;

  // eBPF has one 16-byte instruction: BPF_LD | BPF_DW | BPF_IMM,
  // in this case imm is combined with the next block's imm.
  if (bpf->op == (BPF_CLASS_LD | BPF_SIZE_DW | BPF_MODE_IMM)) {
    if (code_len < 16) {
      cs_mem_free(bpf);
      return NULL;
    }
    bpf->k = read_u32(ud, code + 4) | (((uint64_t)read_u32(ud, code + 12)) << 32);
    bpf->insn_size = 16;
  }
  else {
    bpf->offset = read_u16(ud, code + 2);
    bpf->k = read_u32(ud, code + 4);
  }
  return bpf;
}

#define CHECK_READABLE_REG(ud, reg) do { \
    if (! ((reg) >= BPF_REG_R0 && (reg) <= BPF_REG_R10)) \
      return false; \
  } while (0)

#define CHECK_WRITABLE_REG(ud, reg) do { \
    if (! ((reg) >= BPF_REG_R0 && (reg) < BPF_REG_R10)) \
      return false; \
  } while (0)

#define CHECK_READABLE_AND_PUSH(ud, MI, r) do { \
    CHECK_READABLE_REG(ud, r + BPF_REG_R0); \
    MCOperand_CreateReg0(MI, r + BPF_REG_R0); \
  } while (0)

#define CHECK_WRITABLE_AND_PUSH(ud, MI, r) do { \
    CHECK_WRITABLE_REG(ud, r + BPF_REG_R0); \
    MCOperand_CreateReg0(MI, r + BPF_REG_R0); \
  } while (0)

static bool decodeLoad(cs_struct *ud, MCInst *MI, bpf_internal *bpf)
{
  if (!EBPF_MODE(ud)) {
    /*
     *  +-----+-----------+--------------------+
     *  | ldb |    [k]    |       [x+k]        |
     *  | ldh |    [k]    |       [x+k]        |
     *  +-----+-----------+--------------------+
     */
    if (BPF_SIZE(bpf->op) == BPF_SIZE_DW)
      return false;
    if (BPF_SIZE(bpf->op) == BPF_SIZE_B || BPF_SIZE(bpf->op) == BPF_SIZE_H) {
      /* no ldx */
      if (BPF_CLASS(bpf->op) != BPF_CLASS_LD)
        return false;
      /* can only be BPF_ABS and BPF_IND */
      if (BPF_MODE(bpf->op) == BPF_MODE_ABS) {
        MCOperand_CreateImm0(MI, bpf->k);
        return true;
      }
      else if (BPF_MODE(bpf->op) == BPF_MODE_IND) {
        MCOperand_CreateReg0(MI, BPF_REG_X);
        MCOperand_CreateImm0(MI, bpf->k);
        return true;
      }
      return false;
    }
    /*
     *  +-----+----+------+------+-----+-------+
     *  | ld  | #k | #len | M[k] | [k] | [x+k] |
     *  +-----+----+------+------+-----+-------+
     *  | ldx | #k | #len | M[k] | 4*([k]&0xf) |
     *  +-----+----+------+------+-------------+
     */
    switch (BPF_MODE(bpf->op)) {
    default:
      break;
    case BPF_MODE_IMM:
      MCOperand_CreateImm0(MI, bpf->k);
      return true;
    case BPF_MODE_LEN:
      return true;
    case BPF_MODE_MEM:
      MCOperand_CreateImm0(MI, bpf->k);
      return true;
    }
    if (BPF_CLASS(bpf->op) == BPF_CLASS_LD) {
      if (BPF_MODE(bpf->op) == BPF_MODE_ABS) {
        MCOperand_CreateImm0(MI, bpf->k);
        return true;
      }
      else if (BPF_MODE(bpf->op) == BPF_MODE_IND) {
        MCOperand_CreateReg0(MI, BPF_REG_X);
        MCOperand_CreateImm0(MI, bpf->k);
        return true;
      }
    }
    else { /* LDX */
      if (BPF_MODE(bpf->op) == BPF_MODE_MSH) {
        MCOperand_CreateImm0(MI, bpf->k);
        return true;
      }
    }
    return false;
  }

  /* eBPF mode */
  /*
   * - IMM: lddw dst, imm64
   * - ABS: ld{w,h,b,dw} [k]
   * - IND: ld{w,h,b,dw} [src+k]
   * - MEM: ldx{w,h,b,dw} dst, [src+off]
   */
  if (BPF_CLASS(bpf->op) == BPF_CLASS_LD) {
    switch (BPF_MODE(bpf->op)) {
    case BPF_MODE_IMM:
      if (bpf->op != (BPF_CLASS_LD | BPF_SIZE_DW | BPF_MODE_IMM))
        return false;
      CHECK_WRITABLE_AND_PUSH(ud, MI, bpf->dst);
      MCOperand_CreateImm0(MI, bpf->k);
      return true;
    case BPF_MODE_ABS:
      MCOperand_CreateImm0(MI, bpf->k);
      return true;
    case BPF_MODE_IND:
      CHECK_READABLE_AND_PUSH(ud, MI, bpf->src);
      MCOperand_CreateImm0(MI, bpf->k);
      return true;
    }
    return false;

  }
  /* LDX */
  if (BPF_MODE(bpf->op) == BPF_MODE_MEM) {
    CHECK_WRITABLE_AND_PUSH(ud, MI, bpf->dst);
    CHECK_READABLE_AND_PUSH(ud, MI, bpf->src);
    MCOperand_CreateImm0(MI, bpf->offset);
    return true;
  }
  return false;
}

static bool decodeStore(cs_struct *ud, MCInst *MI, bpf_internal *bpf)
{
  /* in cBPF, only BPF_ST* | BPF_MEM | BPF_W is valid
   * while in eBPF:
   * - BPF_STX | BPF_XADD | BPF_{W,DW}
   * - BPF_ST* | BPF_MEM | BPF_{W,H,B,DW}
   * are valid
   */
  if (!EBPF_MODE(ud)) {
    /* can only store to M[] */
    if (bpf->op != (BPF_CLASS(bpf->op) | BPF_MODE_MEM | BPF_SIZE_W))
      return false;
    MCOperand_CreateImm0(MI, bpf->k);
    return true;
  }

  /* eBPF */

  if (BPF_MODE(bpf->op) == BPF_MODE_XADD) {
    if (BPF_CLASS(bpf->op) != BPF_CLASS_STX)
      return false;
    if (BPF_SIZE(bpf->op) != BPF_SIZE_W && BPF_SIZE(bpf->op) != BPF_SIZE_DW)
      return false;
    /* xadd [dst + off], src */
    CHECK_READABLE_AND_PUSH(ud, MI, bpf->dst);
    MCOperand_CreateImm0(MI, bpf->offset);
    CHECK_READABLE_AND_PUSH(ud, MI, bpf->src);
    return true;
  }

  if (BPF_MODE(bpf->op) != BPF_MODE_MEM)
    return false;

  /* st [dst + off], src */
  CHECK_READABLE_AND_PUSH(ud, MI, bpf->dst);
  MCOperand_CreateImm0(MI, bpf->offset);
  if (BPF_CLASS(bpf->op) == BPF_CLASS_ST)
    MCOperand_CreateImm0(MI, bpf->k);
  else
    CHECK_READABLE_AND_PUSH(ud, MI, bpf->src);
  return true;
}

static bool decodeALU(cs_struct *ud, MCInst *MI, bpf_internal *bpf)
{
  /* Set MI->Operands */

  /* cBPF */
  if (!EBPF_MODE(ud)) {
    if (BPF_OP(bpf->op) > BPF_ALU_XOR)
      return false;
    /* cBPF's NEG has no operands */
    if (BPF_OP(bpf->op) == BPF_ALU_NEG)
      return true;
    if (BPF_SRC(bpf->op) == BPF_SRC_K)
      MCOperand_CreateImm0(MI, bpf->k);
    else /* BPF_SRC_X */
      MCOperand_CreateReg0(MI, BPF_REG_X);
    return true;
  }

  /* eBPF */

  if (BPF_OP(bpf->op) > BPF_ALU_END)
    return false;
  /* ENDian's imm must be one of 16, 32, 64 */
  if (BPF_OP(bpf->op) == BPF_ALU_END) {
    if (bpf->k != 16 && bpf->k != 32 && bpf->k != 64)
      return false;
    if (BPF_CLASS(bpf->op) == BPF_CLASS_ALU64 && BPF_SRC(bpf->op) != BPF_SRC_LITTLE)
      return false;
  }

  /* - op dst, imm
   * - op dst, src
   * - neg dst
   * - le<imm> dst
   */
  /* every ALU instructions have dst op */
  CHECK_WRITABLE_AND_PUSH(ud, MI, bpf->dst);

  /* special cases */
  if (BPF_OP(bpf->op) == BPF_ALU_NEG)
    return true;
  if (BPF_OP(bpf->op) == BPF_ALU_END) {
    /* bpf->k must be one of 16, 32, 64 */
    MCInst_setOpcode(MI, MCInst_getOpcode(MI) | ((uint32_t)bpf->k << 4));
    return true;
  }

  /* normal cases */
  if (BPF_SRC(bpf->op) == BPF_SRC_K) {
    MCOperand_CreateImm0(MI, bpf->k);
  }
  else { /* BPF_SRC_X */
    CHECK_READABLE_AND_PUSH(ud, MI, bpf->src);
  }
  return true;
}

static bool decodeJump(cs_struct *ud, MCInst *MI, bpf_internal *bpf)
{
  /* cBPF and eBPF are very different in class jump */
  if (!EBPF_MODE(ud)) {
    if (BPF_OP(bpf->op) > BPF_JUMP_JSET)
      return false;

    /* ja is a special case of jumps */
    if (BPF_OP(bpf->op) == BPF_JUMP_JA) {
      MCOperand_CreateImm0(MI, bpf->k);
      return true;
    }

    if (BPF_SRC(bpf->op) == BPF_SRC_K)
      MCOperand_CreateImm0(MI, bpf->k);
    else /* BPF_SRC_X */
      MCOperand_CreateReg0(MI, BPF_REG_X);
    MCOperand_CreateImm0(MI, bpf->jt);
    MCOperand_CreateImm0(MI, bpf->jf);
  }
  else {
    if (BPF_OP(bpf->op) > BPF_JUMP_JSLE)
      return false;

    /* No operands for exit */
    if (BPF_OP(bpf->op) == BPF_JUMP_EXIT)
      return bpf->op == (BPF_CLASS_JMP | BPF_JUMP_EXIT);
    if (BPF_OP(bpf->op) == BPF_JUMP_CALL) {
      if (bpf->op == (BPF_CLASS_JMP | BPF_JUMP_CALL)) {
        MCOperand_CreateImm0(MI, bpf->k);
        return true;
      }
      if (bpf->op == (BPF_CLASS_JMP | BPF_JUMP_CALL | BPF_SRC_X)) {
        CHECK_READABLE_AND_PUSH(ud, MI, bpf->k);
        return true;
      }
      return false;
    }

    /* ja is a special case of jumps */
    if (BPF_OP(bpf->op) == BPF_JUMP_JA) {
      if (BPF_SRC(bpf->op) != BPF_SRC_K)
        return false;
      MCOperand_CreateImm0(MI, bpf->offset);
      return true;
    }

    /* <j>  dst, src, +off */
    CHECK_READABLE_AND_PUSH(ud, MI, bpf->dst);
    if (BPF_SRC(bpf->op) == BPF_SRC_K)
      MCOperand_CreateImm0(MI, bpf->k);
    else
      CHECK_READABLE_AND_PUSH(ud, MI, bpf->src);
    MCOperand_CreateImm0(MI, bpf->offset);
  }
  return true;
}

static bool decodeReturn(cs_struct *ud, MCInst *MI, bpf_internal *bpf)
{
  /* Here only handles the BPF_RET class in cBPF */
  switch (BPF_RVAL(bpf->op)) {
  case BPF_SRC_K:
    MCOperand_CreateImm0(MI, bpf->k);
    return true;
  case BPF_SRC_X:
    MCOperand_CreateReg0(MI, BPF_REG_X);
    return true;
  case BPF_SRC_A:
    MCOperand_CreateReg0(MI, BPF_REG_A);
    return true;
  }
  return false;
}

static bool decodeMISC(cs_struct *ud, MCInst *MI, bpf_internal *bpf)
{
  uint16_t op = bpf->op ^ BPF_CLASS_MISC;
  return op == BPF_MISCOP_TAX || op == BPF_MISCOP_TXA;
}

///< 1. Check if the instruction is valid
///< 2. Set MI->opcode
///< 3. Set MI->Operands
static bool getInstruction(cs_struct *ud, MCInst *MI, bpf_internal *bpf)
{
  cs_detail *detail;

  detail = MI->flat_insn->detail;
  // initialize detail
  if (detail) {
    memset(detail, 0, offsetof(cs_detail, bpf) + sizeof(cs_bpf));
  }

  MCInst_clear(MI);
  MCInst_setOpcode(MI, bpf->op);

  switch (BPF_CLASS(bpf->op)) {
  default: /* should never happen */
    return false;
  case BPF_CLASS_LD:
  case BPF_CLASS_LDX:
    return decodeLoad(ud, MI, bpf);
  case BPF_CLASS_ST:
  case BPF_CLASS_STX:
    return decodeStore(ud, MI, bpf);
  case BPF_CLASS_ALU:
    return decodeALU(ud, MI, bpf);
  case BPF_CLASS_JMP:
    return decodeJump(ud, MI, bpf);
  case BPF_CLASS_RET:
    /* eBPF doesn't have this class */
    if (EBPF_MODE(ud))
      return false;
    return decodeReturn(ud, MI, bpf);
  case BPF_CLASS_MISC:
  /* case BPF_CLASS_ALU64: */
    if (EBPF_MODE(ud))
      return decodeALU(ud, MI, bpf);
    else
      return decodeMISC(ud, MI, bpf);
  }
}

bool BPF_getInstruction(csh ud, const uint8_t *code, size_t code_len,
    MCInst *instr, uint16_t *size, uint64_t address, void *info)
{
  cs_struct *cs;
  bpf_internal *bpf;

  cs = (cs_struct*)ud;
  if (EBPF_MODE(cs))
    bpf = fetch_ebpf(cs, code, code_len);
  else
    bpf = fetch_cbpf(cs, code, code_len);
  if (bpf == NULL)
    return false;
  if (!getInstruction(cs, instr, bpf)) {
    cs_mem_free(bpf);
    return false;
  }

  *size = bpf->insn_size;
  cs_mem_free(bpf);

  return true;
}

#endif

Coverage Report

Created: 2024-08-21 06:24

Line	Count	Source (jump to first uncovered line)
1		/* Capstone Disassembly Engine */
2		/* BPF Backend by david942j <david942j@gmail.com>, 2019 */
3
4		#ifdef CAPSTONE_HAS_BPF
5
6		#include <string.h>
7		#include <stddef.h> // offsetof macro
8
9		#include "BPFConstants.h"
10		#include "BPFDisassembler.h"
11		#include "BPFMapping.h"
12		#include "../../cs_priv.h"
13
14		static uint16_t read_u16(cs_struct ud, const uint8_t code)
15	92.0k	{
16	92.0k	if (MODE_IS_BIG_ENDIAN(ud->mode))
17	41.5k	return (((uint16_t)code[0] << 8) \| code[1]);
18	50.5k	else
19	50.5k	return (((uint16_t)code[1] << 8) \| code[0]);
20	92.0k	}
21
22		static uint32_t read_u32(cs_struct ud, const uint8_t code)
23	31.2k	{
24	31.2k	if (MODE_IS_BIG_ENDIAN(ud->mode))
25	14.1k	return ((uint32_t)read_u16(ud, code) << 16) \| read_u16(ud, code + 2);
26	17.1k	else
27	17.1k	return ((uint32_t)read_u16(ud, code + 2) << 16) \| read_u16(ud, code);
28	31.2k	}
29
30		///< Malloc bpf_internal, also checks if code_len is large enough.
31		static bpf_internal *alloc_bpf_internal(size_t code_len)
32	30.7k	{
33	30.7k	bpf_internal *bpf;
34
35	30.7k	if (code_len < 8)
36	396	return NULL;
37	30.3k	bpf = cs_mem_malloc(sizeof(bpf_internal));
38	30.3k	if (bpf == NULL)
39	0	return NULL;
40		/* default value */
41	30.3k	bpf->insn_size = 8;
42	30.3k	return bpf;
43	30.3k	}
44
45		///< Fetch a cBPF structure from code
46		static bpf_internal* fetch_cbpf(cs_struct ud, const uint8_t code,
47		size_t code_len)
48	13.9k	{
49	13.9k	bpf_internal *bpf;
50
51	13.9k	bpf = alloc_bpf_internal(code_len);
52	13.9k	if (bpf == NULL)
53	165	return NULL;
54
55	13.7k	bpf->op = read_u16(ud, code);
56	13.7k	bpf->jt = code[2];
57	13.7k	bpf->jf = code[3];
58	13.7k	bpf->k = read_u32(ud, code + 4);
59	13.7k	return bpf;
60	13.9k	}
61
62		///< Fetch an eBPF structure from code
63		static bpf_internal* fetch_ebpf(cs_struct ud, const uint8_t code,
64		size_t code_len)
65	16.8k	{
66	16.8k	bpf_internal *bpf;
67
68	16.8k	bpf = alloc_bpf_internal(code_len);
69	16.8k	if (bpf == NULL)
70	231	return NULL;
71
72	16.5k	bpf->op = (uint16_t)code[0];
73	16.5k	bpf->dst = code[1] & 0xf;
74	16.5k	bpf->src = (code[1] & 0xf0) >> 4;
75
76		// eBPF has one 16-byte instruction: BPF_LD \| BPF_DW \| BPF_IMM,
77		// in this case imm is combined with the next block's imm.
78	16.5k	if (bpf->op == (BPF_CLASS_LD \| BPF_SIZE_DW \| BPF_MODE_IMM)) {
79	931	if (code_len < 16) {
80	3	cs_mem_free(bpf);
81	3	return NULL;
82	3	}
83	928	bpf->k = read_u32(ud, code + 4) \| (((uint64_t)read_u32(ud, code + 12)) << 32);
84	928	bpf->insn_size = 16;
85	928	}
86	15.6k	else {
87	15.6k	bpf->offset = read_u16(ud, code + 2);
88	15.6k	bpf->k = read_u32(ud, code + 4);
89	15.6k	}
90	16.5k	return bpf;
91	16.5k	}
92
93	9.66k	#define CHECK_READABLE_REG(ud, reg) do { \
94	9.66k	if (! ((reg) >= BPF_REG_R0 && (reg) <= BPF_REG_R10)) \
95	9.66k	return false; \
96	9.66k	} while (0)
97
98	4.68k	#define CHECK_WRITABLE_REG(ud, reg) do { \
99	4.68k	if (! ((reg) >= BPF_REG_R0 && (reg) < BPF_REG_R10)) \
100	4.68k	return false; \
101	4.68k	} while (0)
102
103	9.66k	#define CHECK_READABLE_AND_PUSH(ud, MI, r) do { \
104	9.66k	CHECK_READABLE_REG(ud, r + BPF_REG_R0); \
105	9.66k	MCOperand_CreateReg0(MI, r + BPF_REG_R0); \
106	9.57k	} while (0)
107
108	4.68k	#define CHECK_WRITABLE_AND_PUSH(ud, MI, r) do { \
109	4.68k	CHECK_WRITABLE_REG(ud, r + BPF_REG_R0); \
110	4.68k	MCOperand_CreateReg0(MI, r + BPF_REG_R0); \
111	4.67k	} while (0)
112
113		static bool decodeLoad(cs_struct ud, MCInst MI, bpf_internal *bpf)
114	9.44k	{
115	9.44k	if (!EBPF_MODE(ud)) {
116		/*
117		* +-----+-----------+--------------------+
118		* \| ldb \| [k] \| [x+k] \|
119		* \| ldh \| [k] \| [x+k] \|
120		* +-----+-----------+--------------------+
121		*/
122	4.98k	if (BPF_SIZE(bpf->op) == BPF_SIZE_DW)
123	8	return false;
124	4.97k	if (BPF_SIZE(bpf->op) == BPF_SIZE_B \|\| BPF_SIZE(bpf->op) == BPF_SIZE_H) {
125		/* no ldx */
126	1.13k	if (BPF_CLASS(bpf->op) != BPF_CLASS_LD)
127	12	return false;
128		/* can only be BPF_ABS and BPF_IND */
129	1.12k	if (BPF_MODE(bpf->op) == BPF_MODE_ABS) {
130	498	MCOperand_CreateImm0(MI, bpf->k);
131	498	return true;
132	498	}
133	625	else if (BPF_MODE(bpf->op) == BPF_MODE_IND) {
134	614	MCOperand_CreateReg0(MI, BPF_REG_X);
135	614	MCOperand_CreateImm0(MI, bpf->k);
136	614	return true;
137	614	}
138	11	return false;
139	1.12k	}
140		/*
141		* +-----+----+------+------+-----+-------+
142		* \| ld \| #k \| #len \| M[k] \| [k] \| [x+k] \|
143		* +-----+----+------+------+-----+-------+
144		* \| ldx \| #k \| #len \| M[k] \| 4*([k]&0xf) \|
145		* +-----+----+------+------+-------------+
146		*/
147	3.83k	switch (BPF_MODE(bpf->op)) {
148	1.21k	default:
149	1.21k	break;
150	1.70k	case BPF_MODE_IMM:
151	1.70k	MCOperand_CreateImm0(MI, bpf->k);
152	1.70k	return true;
153	326	case BPF_MODE_LEN:
154	326	return true;
155	588	case BPF_MODE_MEM:
156	588	MCOperand_CreateImm0(MI, bpf->k);
157	588	return true;
158	3.83k	}
159	1.21k	if (BPF_CLASS(bpf->op) == BPF_CLASS_LD) {
160	691	if (BPF_MODE(bpf->op) == BPF_MODE_ABS) {
161	344	MCOperand_CreateImm0(MI, bpf->k);
162	344	return true;
163	344	}
164	347	else if (BPF_MODE(bpf->op) == BPF_MODE_IND) {
165	342	MCOperand_CreateReg0(MI, BPF_REG_X);
166	342	MCOperand_CreateImm0(MI, bpf->k);
167	342	return true;
168	342	}
169	691	}
170	524	else { /* LDX */
171	524	if (BPF_MODE(bpf->op) == BPF_MODE_MSH) {
172	518	MCOperand_CreateImm0(MI, bpf->k);
173	518	return true;
174	518	}
175	524	}
176	11	return false;
177	1.21k	}
178
179		/* eBPF mode */
180		/*
181		* - IMM: lddw dst, imm64
182		* - ABS: ld{w,h,b,dw} [k]
183		* - IND: ld{w,h,b,dw} [src+k]
184		* - MEM: ldx{w,h,b,dw} dst, [src+off]
185		*/
186	4.46k	if (BPF_CLASS(bpf->op) == BPF_CLASS_LD) {
187	3.23k	switch (BPF_MODE(bpf->op)) {
188	968	case BPF_MODE_IMM:
189	968	if (bpf->op != (BPF_CLASS_LD \| BPF_SIZE_DW \| BPF_MODE_IMM))
190	40	return false;
191	928	CHECK_WRITABLE_AND_PUSH(ud, MI, bpf->dst);
192	923	MCOperand_CreateImm0(MI, bpf->k);
193	923	return true;
194	846	case BPF_MODE_ABS:
195	846	MCOperand_CreateImm0(MI, bpf->k);
196	846	return true;
197	1.40k	case BPF_MODE_IND:
198	1.40k	CHECK_READABLE_AND_PUSH(ud, MI, bpf->src);
199	1.39k	MCOperand_CreateImm0(MI, bpf->k);
200	1.39k	return true;
201	3.23k	}
202	18	return false;
203
204	3.23k	}
205		/* LDX */
206	1.23k	if (BPF_MODE(bpf->op) == BPF_MODE_MEM) {
207	1.21k	CHECK_WRITABLE_AND_PUSH(ud, MI, bpf->dst);
208	1.21k	CHECK_READABLE_AND_PUSH(ud, MI, bpf->src);
209	1.21k	MCOperand_CreateImm0(MI, bpf->offset);
210	1.21k	return true;
211	1.21k	}
212	15	return false;
213	1.23k	}
214
215		static bool decodeStore(cs_struct ud, MCInst MI, bpf_internal *bpf)
216	2.76k	{
217		/* in cBPF, only BPF_ST* \| BPF_MEM \| BPF_W is valid
218		* while in eBPF:
219		* - BPF_STX \| BPF_XADD \| BPF_{W,DW}
220		* - BPF_ST* \| BPF_MEM \| BPF_{W,H,B,DW}
221		* are valid
222		*/
223	2.76k	if (!EBPF_MODE(ud)) {
224		/* can only store to M[] */
225	170	if (bpf->op != (BPF_CLASS(bpf->op) \| BPF_MODE_MEM \| BPF_SIZE_W))
226	32	return false;
227	138	MCOperand_CreateImm0(MI, bpf->k);
228	138	return true;
229	170	}
230
231		/* eBPF */
232
233	2.59k	if (BPF_MODE(bpf->op) == BPF_MODE_XADD) {
234	112	if (BPF_CLASS(bpf->op) != BPF_CLASS_STX)
235	3	return false;
236	109	if (BPF_SIZE(bpf->op) != BPF_SIZE_W && BPF_SIZE(bpf->op) != BPF_SIZE_DW)
237	2	return false;
238		/* xadd [dst + off], src */
239	107	CHECK_READABLE_AND_PUSH(ud, MI, bpf->dst);
240	104	MCOperand_CreateImm0(MI, bpf->offset);
241	104	CHECK_READABLE_AND_PUSH(ud, MI, bpf->src);
242	101	return true;
243	104	}
244
245	2.48k	if (BPF_MODE(bpf->op) != BPF_MODE_MEM)
246	21	return false;
247
248		/* st [dst + off], src */
249	2.46k	CHECK_READABLE_AND_PUSH(ud, MI, bpf->dst);
250	2.45k	MCOperand_CreateImm0(MI, bpf->offset);
251	2.45k	if (BPF_CLASS(bpf->op) == BPF_CLASS_ST)
252	1.35k	MCOperand_CreateImm0(MI, bpf->k);
253	1.10k	else
254	1.10k	CHECK_READABLE_AND_PUSH(ud, MI, bpf->src);
255	2.45k	return true;
256	2.45k	}
257
258		static bool decodeALU(cs_struct ud, MCInst MI, bpf_internal *bpf)
259	4.48k	{
260		/* Set MI->Operands */
261
262		/* cBPF */
263	4.48k	if (!EBPF_MODE(ud)) {
264	1.90k	if (BPF_OP(bpf->op) > BPF_ALU_XOR)
265	2	return false;
266		/* cBPF's NEG has no operands */
267	1.90k	if (BPF_OP(bpf->op) == BPF_ALU_NEG)
268	267	return true;
269	1.63k	if (BPF_SRC(bpf->op) == BPF_SRC_K)
270	1.03k	MCOperand_CreateImm0(MI, bpf->k);
271	601	else /* BPF_SRC_X */
272	601	MCOperand_CreateReg0(MI, BPF_REG_X);
273	1.63k	return true;
274	1.90k	}
275
276		/* eBPF */
277
278	2.57k	if (BPF_OP(bpf->op) > BPF_ALU_END)
279	2	return false;
280		/* ENDian's imm must be one of 16, 32, 64 */
281	2.57k	if (BPF_OP(bpf->op) == BPF_ALU_END) {
282	89	if (bpf->k != 16 && bpf->k != 32 && bpf->k != 64)
283	39	return false;
284	50	if (BPF_CLASS(bpf->op) == BPF_CLASS_ALU64 && BPF_SRC(bpf->op) != BPF_SRC_LITTLE)
285	1	return false;
286	50	}
287
288		/* - op dst, imm
289		* - op dst, src
290		* - neg dst
291		* - le<imm> dst
292		*/
293		/* every ALU instructions have dst op */
294	2.53k	CHECK_WRITABLE_AND_PUSH(ud, MI, bpf->dst);
295
296		/* special cases */
297	2.53k	if (BPF_OP(bpf->op) == BPF_ALU_NEG)
298	300	return true;
299	2.23k	if (BPF_OP(bpf->op) == BPF_ALU_END) {
300		/* bpf->k must be one of 16, 32, 64 */
301	47	MCInst_setOpcode(MI, MCInst_getOpcode(MI) \| ((uint32_t)bpf->k << 4));
302	47	return true;
303	47	}
304
305		/* normal cases */
306	2.18k	if (BPF_SRC(bpf->op) == BPF_SRC_K) {
307	1.80k	MCOperand_CreateImm0(MI, bpf->k);
308	1.80k	}
309	384	else { /* BPF_SRC_X */
310	384	CHECK_READABLE_AND_PUSH(ud, MI, bpf->src);
311	384	}
312	2.18k	return true;
313	2.18k	}
314
315		static bool decodeJump(cs_struct ud, MCInst MI, bpf_internal *bpf)
316	6.52k	{
317		/* cBPF and eBPF are very different in class jump */
318	6.52k	if (!EBPF_MODE(ud)) {
319	2.38k	if (BPF_OP(bpf->op) > BPF_JUMP_JSET)
320	8	return false;
321
322		/* ja is a special case of jumps */
323	2.37k	if (BPF_OP(bpf->op) == BPF_JUMP_JA) {
324	887	MCOperand_CreateImm0(MI, bpf->k);
325	887	return true;
326	887	}
327
328	1.48k	if (BPF_SRC(bpf->op) == BPF_SRC_K)
329	761	MCOperand_CreateImm0(MI, bpf->k);
330	726	else /* BPF_SRC_X */
331	726	MCOperand_CreateReg0(MI, BPF_REG_X);
332	1.48k	MCOperand_CreateImm0(MI, bpf->jt);
333	1.48k	MCOperand_CreateImm0(MI, bpf->jf);
334	1.48k	}
335	4.14k	else {
336	4.14k	if (BPF_OP(bpf->op) > BPF_JUMP_JSLE)
337	2	return false;
338
339		/* No operands for exit */
340	4.14k	if (BPF_OP(bpf->op) == BPF_JUMP_EXIT)
341	377	return bpf->op == (BPF_CLASS_JMP \| BPF_JUMP_EXIT);
342	3.76k	if (BPF_OP(bpf->op) == BPF_JUMP_CALL) {
343	776	if (bpf->op == (BPF_CLASS_JMP \| BPF_JUMP_CALL)) {
344	704	MCOperand_CreateImm0(MI, bpf->k);
345	704	return true;
346	704	}
347	72	if (bpf->op == (BPF_CLASS_JMP \| BPF_JUMP_CALL \| BPF_SRC_X)) {
348	72	CHECK_READABLE_AND_PUSH(ud, MI, bpf->k);
349	14	return true;
350	72	}
351	0	return false;
352	72	}
353
354		/* ja is a special case of jumps */
355	2.99k	if (BPF_OP(bpf->op) == BPF_JUMP_JA) {
356	369	if (BPF_SRC(bpf->op) != BPF_SRC_K)
357	2	return false;
358	367	MCOperand_CreateImm0(MI, bpf->offset);
359	367	return true;
360	369	}
361
362		/* <j> dst, src, +off */
363	2.62k	CHECK_READABLE_AND_PUSH(ud, MI, bpf->dst);
364	2.61k	if (BPF_SRC(bpf->op) == BPF_SRC_K)
365	2.41k	MCOperand_CreateImm0(MI, bpf->k);
366	197	else
367	197	CHECK_READABLE_AND_PUSH(ud, MI, bpf->src);
368	2.60k	MCOperand_CreateImm0(MI, bpf->offset);
369	2.60k	}
370	4.09k	return true;
371	6.52k	}
372
373		static bool decodeReturn(cs_struct ud, MCInst MI, bpf_internal *bpf)
374	2.42k	{
375		/* Here only handles the BPF_RET class in cBPF */
376	2.42k	switch (BPF_RVAL(bpf->op)) {
377	759	case BPF_SRC_K:
378	759	MCOperand_CreateImm0(MI, bpf->k);
379	759	return true;
380	971	case BPF_SRC_X:
381	971	MCOperand_CreateReg0(MI, BPF_REG_X);
382	971	return true;
383	691	case BPF_SRC_A:
384	691	MCOperand_CreateReg0(MI, BPF_REG_A);
385	691	return true;
386	2.42k	}
387	5	return false;
388	2.42k	}
389
390		static bool decodeMISC(cs_struct ud, MCInst MI, bpf_internal *bpf)
391	90	{
392	90	uint16_t op = bpf->op ^ BPF_CLASS_MISC;
393	90	return op == BPF_MISCOP_TAX \|\| op == BPF_MISCOP_TXA;
394	90	}
395
396		///< 1. Check if the instruction is valid
397		///< 2. Set MI->opcode
398		///< 3. Set MI->Operands
399		static bool getInstruction(cs_struct ud, MCInst MI, bpf_internal *bpf)
400	30.3k	{
401	30.3k	cs_detail *detail;
402
403	30.3k	detail = MI->flat_insn->detail;
404		// initialize detail
405	30.3k	if (detail) {
406	30.3k	memset(detail, 0, offsetof(cs_detail, bpf) + sizeof(cs_bpf));
407	30.3k	}
408
409	30.3k	MCInst_clear(MI);
410	30.3k	MCInst_setOpcode(MI, bpf->op);
411
412	30.3k	switch (BPF_CLASS(bpf->op)) {
413	0	default: /* should never happen */
414	0	return false;
415	6.91k	case BPF_CLASS_LD:
416	9.44k	case BPF_CLASS_LDX:
417	9.44k	return decodeLoad(ud, MI, bpf);
418	1.48k	case BPF_CLASS_ST:
419	2.76k	case BPF_CLASS_STX:
420	2.76k	return decodeStore(ud, MI, bpf);
421	5.20k	case BPF_CLASS_ALU:
422	5.20k	return decodeALU(ud, MI, bpf);
423	6.52k	case BPF_CLASS_JMP:
424	6.52k	return decodeJump(ud, MI, bpf);
425	2.44k	case BPF_CLASS_RET:
426		/* eBPF doesn't have this class */
427	2.44k	if (EBPF_MODE(ud))
428	21	return false;
429	2.42k	return decodeReturn(ud, MI, bpf);
430	3.98k	case BPF_CLASS_MISC:
431		/* case BPF_CLASS_ALU64: */
432	3.98k	if (EBPF_MODE(ud))
433	3.89k	return decodeALU(ud, MI, bpf);
434	90	else
435	90	return decodeMISC(ud, MI, bpf);
436	30.3k	}
437	30.3k	}
438
439		bool BPF_getInstruction(csh ud, const uint8_t *code, size_t code_len,
440		MCInst instr, uint16_t size, uint64_t address, void *info)
441	30.7k	{
442	30.7k	cs_struct *cs;
443	30.7k	bpf_internal *bpf;
444
445	30.7k	cs = (cs_struct*)ud;
446	30.7k	if (EBPF_MODE(cs))
447	16.8k	bpf = fetch_ebpf(cs, code, code_len);
448	13.9k	else
449	13.9k	bpf = fetch_cbpf(cs, code, code_len);
450	30.7k	if (bpf == NULL)
451	399	return false;
452	30.3k	if (!getInstruction(cs, instr, bpf)) {
453	427	cs_mem_free(bpf);
454	427	return false;
455	427	}
456
457	29.9k	*size = bpf->insn_size;
458	29.9k	cs_mem_free(bpf);
459
460	29.9k	return true;
461	30.3k	}
462
463		#endif