Coverage Report

Created: 2025-11-09 07:00

next uncovered line (L), next uncovered region (R), next uncovered branch (B)
/src/capstonenext/arch/BPF/BPFInstPrinter.c
Line
Count
Source
1
/* Capstone Disassembly Engine */
2
/* BPF Backend by david942j <david942j@gmail.com>, 2019 */
3
/* SPDX-FileCopyrightText: 2024 Roee Toledano <roeetoledano10@gmail.com> */
4
/* SPDX-License-Identifier: BSD-3 */
5
6
#include <capstone/platform.h>
7
8
#include "BPFConstants.h"
9
#include "BPFInstPrinter.h"
10
#include "BPFMapping.h"
11
#include "../../Mapping.h"
12
13
static cs_bpf_op *expand_bpf_operands(cs_bpf *bpf)
14
3.49k
{
15
3.49k
  assert(bpf->op_count < 3);
16
3.49k
  return &bpf->operands[bpf->op_count++];
17
3.49k
}
18
19
static void push_op_reg(cs_bpf *bpf, bpf_op_type val, uint8_t ac_mode)
20
9.33k
{
21
9.33k
  cs_bpf_op *op = expand_bpf_operands(bpf);
22
23
9.33k
  op->type = BPF_OP_REG;
24
9.33k
  op->reg = val;
25
9.33k
  op->access = ac_mode;
26
9.33k
}
27
28
static void push_op_imm(cs_bpf *bpf, uint64_t val, const bool is_signed)
29
6.61k
{
30
6.61k
  cs_bpf_op *op = expand_bpf_operands(bpf);
31
32
6.61k
  op->type = BPF_OP_IMM;
33
6.61k
  op->imm = val;
34
6.61k
  op->is_signed = is_signed;
35
6.61k
}
36
37
static void push_op_off(cs_bpf *bpf, uint32_t val, const bool is_signed)
38
3.45k
{
39
3.45k
  cs_bpf_op *op = expand_bpf_operands(bpf);
40
41
3.45k
  op->type = BPF_OP_OFF;
42
3.45k
  op->off = val;
43
3.45k
  op->is_signed = is_signed;
44
3.45k
}
45
46
static void push_op_mem(cs_bpf *bpf, bpf_reg reg, uint32_t val,
47
      const bool is_signed, const bool is_pkt)
48
4.70k
{
49
4.70k
  cs_bpf_op *op = expand_bpf_operands(bpf);
50
51
4.70k
  op->type = BPF_OP_MEM;
52
4.70k
  op->mem.base = reg;
53
4.70k
  op->mem.disp = val;
54
4.70k
  op->is_signed = is_signed;
55
4.70k
  op->is_pkt = is_pkt;
56
4.70k
}
57
58
static void push_op_mmem(cs_bpf *bpf, uint32_t val)
59
502
{
60
502
  cs_bpf_op *op = expand_bpf_operands(bpf);
61
62
502
  op->type = BPF_OP_MMEM;
63
502
  op->mmem = val;
64
502
}
65
66
static void push_op_msh(cs_bpf *bpf, uint32_t val)
67
345
{
68
345
  cs_bpf_op *op = expand_bpf_operands(bpf);
69
70
345
  op->type = BPF_OP_MSH;
71
345
  op->msh = val;
72
345
}
73
74
static void push_op_ext(cs_bpf *bpf, bpf_ext_type val)
75
277
{
76
277
  cs_bpf_op *op = expand_bpf_operands(bpf);
77
78
277
  op->type = BPF_OP_EXT;
79
277
  op->ext = val;
80
277
}
81
82
static void convert_operands(MCInst *MI, cs_bpf *bpf)
83
2.17k
{
84
2.17k
  unsigned opcode = MCInst_getOpcode(MI);
85
2.17k
  unsigned mc_op_count = MCInst_getNumOperands(MI);
86
2.17k
  MCOperand *op;
87
2.17k
  MCOperand *op2;
88
89
2.17k
  bpf->op_count = 0;
90
2.17k
  if (BPF_CLASS(opcode) == BPF_CLASS_LD ||
91
1.68k
      BPF_CLASS(opcode) == BPF_CLASS_LDX) {
92
790
    switch (BPF_MODE(opcode)) {
93
15
    case BPF_MODE_IMM:
94
15
      if (EBPF_MODE(MI->csh->mode)) {
95
3
        push_op_reg(bpf,
96
3
              MCOperand_getReg(
97
3
                MCInst_getOperand(MI, 0)),
98
3
              CS_AC_WRITE);
99
3
        push_op_imm(bpf,
100
3
              MCOperand_getImm(
101
3
                MCInst_getOperand(MI, 1)),
102
3
              false);
103
12
      } else {
104
12
        push_op_imm(bpf,
105
12
              MCOperand_getImm(
106
12
                MCInst_getOperand(MI, 0)),
107
12
              false);
108
12
      }
109
15
      break;
110
73
    case BPF_MODE_ABS:
111
73
      op = MCInst_getOperand(MI, 0);
112
73
      push_op_mem(bpf, BPF_REG_INVALID,
113
73
            (uint32_t)MCOperand_getImm(op),
114
73
            EBPF_MODE(MI->csh->mode), true);
115
73
      break;
116
396
    case BPF_MODE_IND:
117
396
      op = MCInst_getOperand(MI, 0);
118
396
      if (EBPF_MODE(MI->csh->mode))
119
357
        push_op_mem(bpf, MCOperand_getReg(op), 0x0,
120
357
              true, true);
121
39
      else {
122
39
        op2 = MCInst_getOperand(MI, 1);
123
39
        push_op_mem(bpf, MCOperand_getReg(op),
124
39
              (uint32_t)MCOperand_getImm(op2),
125
39
              false, true);
126
39
      }
127
396
      break;
128
149
    case BPF_MODE_MEM:
129
149
      if (EBPF_MODE(MI->csh->mode)) {
130
        /* ldx{w,h,b,dw} dst, [src+off] */
131
132
        push_op_reg(bpf,
132
132
              MCOperand_getReg(
133
132
                MCInst_getOperand(MI, 0)),
134
132
              CS_AC_WRITE);
135
132
        op = MCInst_getOperand(MI, 1);
136
132
        op2 = MCInst_getOperand(MI, 2);
137
132
        push_op_mem(bpf, MCOperand_getReg(op),
138
132
              (uint32_t)MCOperand_getImm(op2),
139
132
              true, false);
140
132
      } else {
141
17
        push_op_mmem(bpf,
142
17
               (uint32_t)MCOperand_getImm(
143
17
                 MCInst_getOperand(MI, 0)));
144
17
      }
145
149
      break;
146
6
    case BPF_MODE_LEN:
147
6
      push_op_ext(bpf, BPF_EXT_LEN);
148
6
      break;
149
151
    case BPF_MODE_MSH:
150
151
      op = MCInst_getOperand(MI, 0);
151
151
      push_op_msh(bpf, (uint32_t)MCOperand_getImm(op));
152
151
      break;
153
      /* case BPF_MODE_XADD: // not exists */
154
790
    }
155
790
    return;
156
790
  }
157
1.38k
  if (BPF_CLASS(opcode) == BPF_CLASS_ST ||
158
1.35k
      BPF_CLASS(opcode) == BPF_CLASS_STX) {
159
98
    if (!EBPF_MODE(MI->csh->mode)) {
160
      // cBPF has only one case - st* M[k]
161
0
      push_op_mmem(bpf, (uint32_t)MCOperand_getImm(
162
0
              MCInst_getOperand(MI, 0)));
163
0
      return;
164
0
    }
165
    /* eBPF has two cases:
166
     * - st [dst + off], src
167
     * - xadd [dst + off], src
168
     * they have same form of operands.
169
     */
170
98
    op = MCInst_getOperand(MI, 0);
171
98
    op2 = MCInst_getOperand(MI, 1);
172
98
    push_op_mem(bpf, MCOperand_getReg(op),
173
98
          (uint32_t)MCOperand_getImm(op2), true, false);
174
175
98
    op = MCInst_getOperand(MI, 2);
176
98
    if (MCOperand_isImm(op))
177
24
      push_op_imm(bpf, MCOperand_getImm(op), false);
178
74
    else if (MCOperand_isReg(op))
179
74
      push_op_reg(bpf, MCOperand_getReg(op), CS_AC_READ);
180
98
    return;
181
98
  }
182
183
1.28k
  {
184
1.28k
    const bool is_jmp32 = EBPF_MODE(MI->csh->mode) &&
185
959
              (BPF_CLASS(opcode) == BPF_CLASS_JMP32);
186
1.28k
    if (BPF_CLASS(opcode) == BPF_CLASS_JMP || is_jmp32) {
187
1.67k
      for (size_t i = 0; i < mc_op_count; i++) {
188
1.16k
        op = MCInst_getOperand(MI, i);
189
1.16k
        if (MCOperand_isImm(op)) {
190
          /* Decide if we're using IMM or OFF here (and if OFF, then signed or unsigned):
191
           *
192
           * 1. any jump/jump32 + signed off (not including exit/call and ja on jump32) // eBPF 
193
           * 2. exit/call/ja + k // eBPF
194
           * 3. ja + unsigned off // cBPF (cBPF programs can only jump forwards) 
195
           * 4. any jump {x,k}, +jt, +jf // cBPF 
196
           * */
197
198
848
          if ((BPF_OP(opcode) == BPF_JUMP_JA &&
199
23
               !is_jmp32) ||
200
829
              (!EBPF_MODE(MI->csh->mode) &&
201
122
               i >= 1) ||
202
727
              (EBPF_MODE(MI->csh->mode) &&
203
707
               i == 2))
204
402
            push_op_off(
205
402
              bpf,
206
402
              MCOperand_getImm(op),
207
402
              EBPF_MODE(
208
402
                MI->csh->mode));
209
446
          else
210
446
            push_op_imm(
211
446
              bpf,
212
446
              MCOperand_getImm(op),
213
446
              true);
214
848
        } else if (MCOperand_isReg(op)) {
215
318
          push_op_reg(bpf, MCOperand_getReg(op),
216
318
                CS_AC_READ);
217
318
        }
218
1.16k
      }
219
508
      return;
220
508
    }
221
1.28k
  }
222
223
776
  if (!EBPF_MODE(MI->csh->mode)) {
224
    /* In cBPF mode, all registers in operands are accessed as read */
225
503
    for (size_t i = 0; i < mc_op_count; i++) {
226
247
      op = MCInst_getOperand(MI, i);
227
247
      if (MCOperand_isImm(op))
228
74
        push_op_imm(bpf, MCOperand_getImm(op), false);
229
173
      else if (MCOperand_isReg(op))
230
173
        push_op_reg(bpf, MCOperand_getReg(op),
231
173
              CS_AC_READ);
232
247
    }
233
256
    return;
234
256
  }
235
236
  /* remain cases are: eBPF mode && ALU */
237
  /* if (BPF_CLASS(opcode) == BPF_CLASS_ALU || BPF_CLASS(opcode) == BPF_CLASS_ALU64) */
238
239
  /* We have three types:
240
   * 1. {l,b}e dst               // dst = byteswap(dst)
241
   * 2. neg dst                  // dst = -dst
242
   * 3. <op> dst, {src_reg, imm} // dst = dst <op> src
243
   * so we can simply check the number of operands,
244
   * exactly one operand means we are in case 1. and 2.,
245
   * otherwise in case 3.
246
   */
247
520
  if (mc_op_count == 1) {
248
83
    op = MCInst_getOperand(MI, 0);
249
83
    push_op_reg(bpf, MCOperand_getReg(op),
250
83
          CS_AC_READ | CS_AC_WRITE);
251
437
  } else { // if (mc_op_count == 2)
252
437
    op = MCInst_getOperand(MI, 0);
253
437
    push_op_reg(bpf, MCOperand_getReg(op),
254
437
          CS_AC_READ | CS_AC_WRITE);
255
256
437
    op = MCInst_getOperand(MI, 1);
257
437
    if (MCOperand_isImm(op))
258
404
      push_op_imm(bpf, MCOperand_getImm(op), false);
259
33
    else if (MCOperand_isReg(op))
260
33
      push_op_reg(bpf, MCOperand_getReg(op), CS_AC_READ);
261
437
  }
262
520
}
263
264
static void print_operand(MCInst *MI, struct SStream *O, const cs_bpf_op *op)
265
3.49k
{
266
3.49k
  switch (op->type) {
267
0
  case BPF_OP_INVALID:
268
0
    SStream_concat(O, "invalid");
269
0
    break;
270
1.25k
  case BPF_OP_REG:
271
1.25k
    SStream_concat(O, BPF_reg_name((csh)MI->csh, op->reg));
272
1.25k
    break;
273
963
  case BPF_OP_IMM:
274
963
    if (op->is_signed)
275
446
      printInt32Hex(O, op->imm);
276
517
    else
277
517
      SStream_concat(O, "0x%" PRIx64, op->imm);
278
963
    break;
279
402
  case BPF_OP_OFF:
280
402
    if (op->is_signed)
281
282
      printInt16HexOffset(O, op->off);
282
120
    else
283
120
      SStream_concat(O, "+0x%" PRIx32, op->off);
284
402
    break;
285
699
  case BPF_OP_MEM:
286
699
    SStream_concat(O, "[");
287
288
699
    if (op->is_pkt && EBPF_MODE(MI->csh->mode)) {
289
391
      SStream_concat(O, "skb");
290
291
391
      if (op->mem.base != BPF_REG_INVALID)
292
357
        SStream_concat(O, "+%s",
293
357
                 BPF_reg_name((csh)MI->csh,
294
357
                  op->mem.base));
295
34
      else {
296
34
        if (op->is_signed)
297
34
          printInt32HexOffset(O, op->mem.disp);
298
0
        else
299
0
          SStream_concat(O, "+0x%" PRIx32,
300
0
                   op->mem.disp);
301
34
      }
302
391
    } else {
303
308
      if (op->mem.base != BPF_REG_INVALID)
304
269
        SStream_concat(O, BPF_reg_name((csh)MI->csh,
305
269
                     op->mem.base));
306
308
      if (op->mem.disp != 0) {
307
293
        if (op->mem.base != BPF_REG_INVALID) {
308
          // if operation is signed, then it always uses off, not k
309
254
          if (op->is_signed)
310
215
            printInt16HexOffset(
311
215
              O, op->mem.disp);
312
39
          else if (op->is_pkt)
313
39
            SStream_concat(O, "+0x%" PRIx32,
314
39
                     op->mem.disp);
315
0
          else
316
0
            SStream_concat(O, "+0x%" PRIx16,
317
0
                     op->mem.disp);
318
254
        } else
319
39
          SStream_concat(O, "0x%" PRIx32,
320
39
                   op->mem.disp);
321
293
      }
322
323
308
      if (op->mem.base == BPF_REG_INVALID &&
324
39
          op->mem.disp == 0)
325
0
        SStream_concat(O, "0x0");
326
308
    }
327
328
699
    SStream_concat(O, "]");
329
699
    break;
330
17
  case BPF_OP_MMEM:
331
17
    SStream_concat(O, "m[0x%x]", op->mmem);
332
17
    break;
333
151
  case BPF_OP_MSH:
334
151
    SStream_concat(O, "4*([0x%x]&0xf)", op->msh);
335
151
    break;
336
6
  case BPF_OP_EXT:
337
6
    switch (op->ext) {
338
6
    case BPF_EXT_LEN:
339
6
      SStream_concat(O, "#len");
340
6
      break;
341
6
    }
342
6
    break;
343
3.49k
  }
344
3.49k
}
345
346
/*
347
 * 1. human readable mnemonic
348
 * 2. set pubOpcode (BPF_INSN_*)
349
 * 3. set detail->bpf.operands
350
 * */
351
void BPF_printInst(MCInst *MI, struct SStream *O, void *PrinterInfo)
352
16.5k
{
353
16.5k
  cs_bpf bpf = { 0 };
354
355
  /* set pubOpcode as instruction id */
356
16.5k
  SStream_concat(O, BPF_insn_name((csh)MI->csh, MCInst_getOpcodePub(MI)));
357
16.5k
  convert_operands(MI, &bpf);
358
41.7k
  for (size_t i = 0; i < bpf.op_count; i++) {
359
25.2k
    if (i == 0)
360
15.6k
      SStream_concat(O, "\t");
361
9.54k
    else
362
9.54k
      SStream_concat(O, ", ");
363
25.2k
    print_operand(MI, O, &bpf.operands[i]);
364
25.2k
  }
365
366
16.5k
#ifndef CAPSTONE_DIET
367
16.5k
  if (detail_is_set(MI)) {
368
16.5k
    MI->flat_insn->detail->bpf = bpf;
369
16.5k
  }
370
16.5k
#endif
371
16.5k
}