Coverage Report

Created: 2026-03-03 06:14

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
13.0k
{
15
13.0k
  assert(bpf->op_count < 3);
16
13.0k
  return &bpf->operands[bpf->op_count++];
17
13.0k
}
18
19
static void push_op_reg(cs_bpf *bpf, bpf_op_type val, uint8_t ac_mode)
20
4.52k
{
21
4.52k
  cs_bpf_op *op = expand_bpf_operands(bpf);
22
23
4.52k
  op->type = BPF_OP_REG;
24
4.52k
  op->reg = val;
25
4.52k
  op->access = ac_mode;
26
4.52k
}
27
28
static void push_op_imm(cs_bpf *bpf, uint64_t val, const bool is_signed)
29
3.21k
{
30
3.21k
  cs_bpf_op *op = expand_bpf_operands(bpf);
31
32
3.21k
  op->type = BPF_OP_IMM;
33
3.21k
  op->imm = val;
34
3.21k
  op->is_signed = is_signed;
35
3.21k
}
36
37
static void push_op_off(cs_bpf *bpf, uint32_t val, const bool is_signed)
38
2.27k
{
39
2.27k
  cs_bpf_op *op = expand_bpf_operands(bpf);
40
41
2.27k
  op->type = BPF_OP_OFF;
42
2.27k
  op->off = val;
43
2.27k
  op->is_signed = is_signed;
44
2.27k
}
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
2.47k
{
49
2.47k
  cs_bpf_op *op = expand_bpf_operands(bpf);
50
51
2.47k
  op->type = BPF_OP_MEM;
52
2.47k
  op->mem.base = reg;
53
2.47k
  op->mem.disp = val;
54
2.47k
  op->is_signed = is_signed;
55
2.47k
  op->is_pkt = is_pkt;
56
2.47k
}
57
58
static void push_op_mmem(cs_bpf *bpf, uint32_t val)
59
568
{
60
568
  cs_bpf_op *op = expand_bpf_operands(bpf);
61
62
568
  op->type = BPF_OP_MMEM;
63
568
  op->mmem = val;
64
568
}
65
66
static void push_op_msh(cs_bpf *bpf, uint32_t val)
67
11
{
68
11
  cs_bpf_op *op = expand_bpf_operands(bpf);
69
70
11
  op->type = BPF_OP_MSH;
71
11
  op->msh = val;
72
11
}
73
74
static void push_op_ext(cs_bpf *bpf, bpf_ext_type val)
75
7
{
76
7
  cs_bpf_op *op = expand_bpf_operands(bpf);
77
78
7
  op->type = BPF_OP_EXT;
79
7
  op->ext = val;
80
7
}
81
82
static void convert_operands(MCInst *MI, cs_bpf *bpf)
83
8.12k
{
84
8.12k
  unsigned opcode = MCInst_getOpcode(MI);
85
8.12k
  unsigned mc_op_count = MCInst_getNumOperands(MI);
86
8.12k
  MCOperand *op;
87
8.12k
  MCOperand *op2;
88
89
8.12k
  bpf->op_count = 0;
90
8.12k
  if (BPF_CLASS(opcode) == BPF_CLASS_LD ||
91
6.23k
      BPF_CLASS(opcode) == BPF_CLASS_LDX) {
92
3.00k
    switch (BPF_MODE(opcode)) {
93
264
    case BPF_MODE_IMM:
94
264
      if (EBPF_MODE(MI->csh->mode)) {
95
38
        push_op_reg(bpf,
96
38
              MCOperand_getReg(
97
38
                MCInst_getOperand(MI, 0)),
98
38
              CS_AC_WRITE);
99
38
        push_op_imm(bpf,
100
38
              MCOperand_getImm(
101
38
                MCInst_getOperand(MI, 1)),
102
38
              false);
103
226
      } else {
104
226
        push_op_imm(bpf,
105
226
              MCOperand_getImm(
106
226
                MCInst_getOperand(MI, 0)),
107
226
              false);
108
226
      }
109
264
      break;
110
924
    case BPF_MODE_ABS:
111
924
      op = MCInst_getOperand(MI, 0);
112
924
      push_op_mem(bpf, BPF_REG_INVALID,
113
924
            (uint32_t)MCOperand_getImm(op),
114
924
            EBPF_MODE(MI->csh->mode), true);
115
924
      break;
116
687
    case BPF_MODE_IND:
117
687
      op = MCInst_getOperand(MI, 0);
118
687
      if (EBPF_MODE(MI->csh->mode))
119
270
        push_op_mem(bpf, MCOperand_getReg(op), 0x0,
120
270
              true, true);
121
417
      else {
122
417
        op2 = MCInst_getOperand(MI, 1);
123
417
        push_op_mem(bpf, MCOperand_getReg(op),
124
417
              (uint32_t)MCOperand_getImm(op2),
125
417
              false, true);
126
417
      }
127
687
      break;
128
1.11k
    case BPF_MODE_MEM:
129
1.11k
      if (EBPF_MODE(MI->csh->mode)) {
130
        /* ldx{w,h,b,dw} dst, [src+off] */
131
545
        push_op_reg(bpf,
132
545
              MCOperand_getReg(
133
545
                MCInst_getOperand(MI, 0)),
134
545
              CS_AC_WRITE);
135
545
        op = MCInst_getOperand(MI, 1);
136
545
        op2 = MCInst_getOperand(MI, 2);
137
545
        push_op_mem(bpf, MCOperand_getReg(op),
138
545
              (uint32_t)MCOperand_getImm(op2),
139
545
              true, false);
140
566
      } else {
141
566
        push_op_mmem(bpf,
142
566
               (uint32_t)MCOperand_getImm(
143
566
                 MCInst_getOperand(MI, 0)));
144
566
      }
145
1.11k
      break;
146
7
    case BPF_MODE_LEN:
147
7
      push_op_ext(bpf, BPF_EXT_LEN);
148
7
      break;
149
11
    case BPF_MODE_MSH:
150
11
      op = MCInst_getOperand(MI, 0);
151
11
      push_op_msh(bpf, (uint32_t)MCOperand_getImm(op));
152
11
      break;
153
      /* case BPF_MODE_XADD: // not exists */
154
3.00k
    }
155
3.00k
    return;
156
3.00k
  }
157
5.12k
  if (BPF_CLASS(opcode) == BPF_CLASS_ST ||
158
4.99k
      BPF_CLASS(opcode) == BPF_CLASS_STX) {
159
320
    if (!EBPF_MODE(MI->csh->mode)) {
160
      // cBPF has only one case - st* M[k]
161
2
      push_op_mmem(bpf, (uint32_t)MCOperand_getImm(
162
2
              MCInst_getOperand(MI, 0)));
163
2
      return;
164
2
    }
165
    /* eBPF has two cases:
166
     * - st [dst + off], src
167
     * - xadd [dst + off], src
168
     * they have same form of operands.
169
     */
170
318
    op = MCInst_getOperand(MI, 0);
171
318
    op2 = MCInst_getOperand(MI, 1);
172
318
    push_op_mem(bpf, MCOperand_getReg(op),
173
318
          (uint32_t)MCOperand_getImm(op2), true, false);
174
175
318
    op = MCInst_getOperand(MI, 2);
176
318
    if (MCOperand_isImm(op))
177
120
      push_op_imm(bpf, MCOperand_getImm(op), false);
178
198
    else if (MCOperand_isReg(op))
179
198
      push_op_reg(bpf, MCOperand_getReg(op), CS_AC_READ);
180
318
    return;
181
320
  }
182
183
4.80k
  {
184
4.80k
    const bool is_jmp32 = EBPF_MODE(MI->csh->mode) &&
185
3.12k
              (BPF_CLASS(opcode) == BPF_CLASS_JMP32);
186
4.80k
    if (BPF_CLASS(opcode) == BPF_CLASS_JMP || is_jmp32) {
187
7.51k
      for (size_t i = 0; i < mc_op_count; i++) {
188
5.32k
        op = MCInst_getOperand(MI, i);
189
5.32k
        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
3.76k
          if ((BPF_OP(opcode) == BPF_JUMP_JA &&
199
545
               !is_jmp32) ||
200
3.39k
              (!EBPF_MODE(MI->csh->mode) &&
201
739
               i >= 1) ||
202
2.74k
              (EBPF_MODE(MI->csh->mode) &&
203
2.65k
               i == 2))
204
2.27k
            push_op_off(
205
2.27k
              bpf,
206
2.27k
              MCOperand_getImm(op),
207
2.27k
              EBPF_MODE(
208
2.27k
                MI->csh->mode));
209
1.49k
          else
210
1.49k
            push_op_imm(
211
1.49k
              bpf,
212
1.49k
              MCOperand_getImm(op),
213
1.49k
              true);
214
3.76k
        } else if (MCOperand_isReg(op)) {
215
1.56k
          push_op_reg(bpf, MCOperand_getReg(op),
216
1.56k
                CS_AC_READ);
217
1.56k
        }
218
5.32k
      }
219
2.19k
      return;
220
2.19k
    }
221
4.80k
  }
222
223
2.60k
  if (!EBPF_MODE(MI->csh->mode)) {
224
    /* In cBPF mode, all registers in operands are accessed as read */
225
1.96k
    for (size_t i = 0; i < mc_op_count; i++) {
226
938
      op = MCInst_getOperand(MI, i);
227
938
      if (MCOperand_isImm(op))
228
478
        push_op_imm(bpf, MCOperand_getImm(op), false);
229
460
      else if (MCOperand_isReg(op))
230
460
        push_op_reg(bpf, MCOperand_getReg(op),
231
460
              CS_AC_READ);
232
938
    }
233
1.02k
    return;
234
1.02k
  }
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
1.57k
  if (mc_op_count == 1) {
248
568
    op = MCInst_getOperand(MI, 0);
249
568
    push_op_reg(bpf, MCOperand_getReg(op),
250
568
          CS_AC_READ | CS_AC_WRITE);
251
1.00k
  } else { // if (mc_op_count == 2)
252
1.00k
    op = MCInst_getOperand(MI, 0);
253
1.00k
    push_op_reg(bpf, MCOperand_getReg(op),
254
1.00k
          CS_AC_READ | CS_AC_WRITE);
255
256
1.00k
    op = MCInst_getOperand(MI, 1);
257
1.00k
    if (MCOperand_isImm(op))
258
862
      push_op_imm(bpf, MCOperand_getImm(op), false);
259
147
    else if (MCOperand_isReg(op))
260
147
      push_op_reg(bpf, MCOperand_getReg(op), CS_AC_READ);
261
1.00k
  }
262
1.57k
}
263
264
static void print_operand(MCInst *MI, struct SStream *O, const cs_bpf_op *op)
265
13.0k
{
266
13.0k
  switch (op->type) {
267
0
  case BPF_OP_INVALID:
268
0
    SStream_concat(O, "invalid");
269
0
    break;
270
4.52k
  case BPF_OP_REG:
271
4.52k
    SStream_concat(O, BPF_reg_name((csh)MI->csh, op->reg));
272
4.52k
    break;
273
3.21k
  case BPF_OP_IMM:
274
3.21k
    if (op->is_signed)
275
1.49k
      printInt32Hex(O, op->imm);
276
1.72k
    else
277
1.72k
      SStream_concat(O, "0x%" PRIx64, op->imm);
278
3.21k
    break;
279
2.27k
  case BPF_OP_OFF:
280
2.27k
    if (op->is_signed)
281
1.29k
      printInt16HexOffset(O, op->off);
282
980
    else
283
980
      SStream_concat(O, "+0x%" PRIx32, op->off);
284
2.27k
    break;
285
2.47k
  case BPF_OP_MEM:
286
2.47k
    SStream_concat(O, "[");
287
288
2.47k
    if (op->is_pkt && EBPF_MODE(MI->csh->mode)) {
289
1.05k
      SStream_concat(O, "skb");
290
291
1.05k
      if (op->mem.base != BPF_REG_INVALID)
292
270
        SStream_concat(O, "+%s",
293
270
                 BPF_reg_name((csh)MI->csh,
294
270
                  op->mem.base));
295
789
      else {
296
789
        if (op->is_signed)
297
789
          printInt32HexOffset(O, op->mem.disp);
298
0
        else
299
0
          SStream_concat(O, "+0x%" PRIx32,
300
0
                   op->mem.disp);
301
789
      }
302
1.41k
    } else {
303
1.41k
      if (op->mem.base != BPF_REG_INVALID)
304
1.28k
        SStream_concat(O, BPF_reg_name((csh)MI->csh,
305
1.28k
                     op->mem.base));
306
1.41k
      if (op->mem.disp != 0) {
307
1.34k
        if (op->mem.base != BPF_REG_INVALID) {
308
          // if operation is signed, then it always uses off, not k
309
1.24k
          if (op->is_signed)
310
835
            printInt16HexOffset(
311
835
              O, op->mem.disp);
312
410
          else if (op->is_pkt)
313
410
            SStream_concat(O, "+0x%" PRIx32,
314
410
                     op->mem.disp);
315
0
          else
316
0
            SStream_concat(O, "+0x%" PRIx16,
317
0
                     op->mem.disp);
318
1.24k
        } else
319
99
          SStream_concat(O, "0x%" PRIx32,
320
99
                   op->mem.disp);
321
1.34k
      }
322
323
1.41k
      if (op->mem.base == BPF_REG_INVALID &&
324
135
          op->mem.disp == 0)
325
36
        SStream_concat(O, "0x0");
326
1.41k
    }
327
328
2.47k
    SStream_concat(O, "]");
329
2.47k
    break;
330
568
  case BPF_OP_MMEM:
331
568
    SStream_concat(O, "m[0x%x]", op->mmem);
332
568
    break;
333
11
  case BPF_OP_MSH:
334
11
    SStream_concat(O, "4*([0x%x]&0xf)", op->msh);
335
11
    break;
336
7
  case BPF_OP_EXT:
337
7
    switch (op->ext) {
338
7
    case BPF_EXT_LEN:
339
7
      SStream_concat(O, "#len");
340
7
      break;
341
7
    }
342
7
    break;
343
13.0k
  }
344
13.0k
}
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
8.12k
{
353
8.12k
  cs_bpf bpf = { 0 };
354
355
  /* set pubOpcode as instruction id */
356
8.12k
  SStream_concat(O, BPF_insn_name((csh)MI->csh, MCInst_getOpcodePub(MI)));
357
8.12k
  convert_operands(MI, &bpf);
358
21.1k
  for (size_t i = 0; i < bpf.op_count; i++) {
359
13.0k
    if (i == 0)
360
8.00k
      SStream_concat(O, "\t");
361
5.06k
    else
362
5.06k
      SStream_concat(O, ", ");
363
13.0k
    print_operand(MI, O, &bpf.operands[i]);
364
13.0k
  }
365
366
8.12k
#ifndef CAPSTONE_DIET
367
8.12k
  if (detail_is_set(MI)) {
368
8.12k
    MI->flat_insn->detail->bpf = bpf;
369
8.12k
  }
370
8.12k
#endif
371
8.12k
}