Coverage Report

Created: 2026-11-12 06:22

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
38.8k
{
15
38.8k
  assert(bpf->op_count < 3);
16
38.8k
  return &bpf->operands[bpf->op_count++];
17
38.8k
}
18
19
static void push_op_reg(cs_bpf *bpf, bpf_op_type val, uint8_t ac_mode)
20
14.7k
{
21
14.7k
  cs_bpf_op *op = expand_bpf_operands(bpf);
22
23
14.7k
  op->type = BPF_OP_REG;
24
14.7k
  op->reg = val;
25
14.7k
  op->access = ac_mode;
26
14.7k
}
27
28
static void push_op_imm(cs_bpf *bpf, uint64_t val, const bool is_signed)
29
10.5k
{
30
10.5k
  cs_bpf_op *op = expand_bpf_operands(bpf);
31
32
10.5k
  op->type = BPF_OP_IMM;
33
10.5k
  op->imm = val;
34
10.5k
  op->is_signed = is_signed;
35
10.5k
}
36
37
static void push_op_off(cs_bpf *bpf, uint32_t val, const bool is_signed)
38
6.24k
{
39
6.24k
  cs_bpf_op *op = expand_bpf_operands(bpf);
40
41
6.24k
  op->type = BPF_OP_OFF;
42
6.24k
  op->off = val;
43
6.24k
  op->is_signed = is_signed;
44
6.24k
}
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
6.53k
{
49
6.53k
  cs_bpf_op *op = expand_bpf_operands(bpf);
50
51
6.53k
  op->type = BPF_OP_MEM;
52
6.53k
  op->mem.base = reg;
53
6.53k
  op->mem.disp = val;
54
6.53k
  op->is_signed = is_signed;
55
6.53k
  op->is_pkt = is_pkt;
56
6.53k
}
57
58
static void push_op_mmem(cs_bpf *bpf, uint32_t val)
59
312
{
60
312
  cs_bpf_op *op = expand_bpf_operands(bpf);
61
62
312
  op->type = BPF_OP_MMEM;
63
312
  op->mmem = val;
64
312
}
65
66
static void push_op_msh(cs_bpf *bpf, uint32_t val)
67
195
{
68
195
  cs_bpf_op *op = expand_bpf_operands(bpf);
69
70
195
  op->type = BPF_OP_MSH;
71
195
  op->msh = val;
72
195
}
73
74
static void push_op_ext(cs_bpf *bpf, bpf_ext_type val)
75
331
{
76
331
  cs_bpf_op *op = expand_bpf_operands(bpf);
77
78
331
  op->type = BPF_OP_EXT;
79
331
  op->ext = val;
80
331
}
81
82
static void convert_operands(MCInst *MI, cs_bpf *bpf)
83
22.5k
{
84
22.5k
  unsigned opcode = MCInst_getOpcode(MI);
85
22.5k
  unsigned mc_op_count = MCInst_getNumOperands(MI);
86
22.5k
  MCOperand *op;
87
22.5k
  MCOperand *op2;
88
89
22.5k
  bpf->op_count = 0;
90
22.5k
  if (BPF_CLASS(opcode) == BPF_CLASS_LD ||
91
18.7k
      BPF_CLASS(opcode) == BPF_CLASS_LDX) {
92
5.24k
    switch (BPF_MODE(opcode)) {
93
821
    case BPF_MODE_IMM:
94
821
      if (EBPF_MODE(MI->csh->mode)) {
95
238
        push_op_reg(bpf,
96
238
              MCOperand_getReg(
97
238
                MCInst_getOperand(MI, 0)),
98
238
              CS_AC_WRITE);
99
238
        push_op_imm(bpf,
100
238
              MCOperand_getImm(
101
238
                MCInst_getOperand(MI, 1)),
102
238
              false);
103
583
      } else {
104
583
        push_op_imm(bpf,
105
583
              MCOperand_getImm(
106
583
                MCInst_getOperand(MI, 0)),
107
583
              false);
108
583
      }
109
821
      break;
110
1.61k
    case BPF_MODE_ABS:
111
1.61k
      op = MCInst_getOperand(MI, 0);
112
1.61k
      push_op_mem(bpf, BPF_REG_INVALID,
113
1.61k
            (uint32_t)MCOperand_getImm(op),
114
1.61k
            EBPF_MODE(MI->csh->mode), true);
115
1.61k
      break;
116
1.28k
    case BPF_MODE_IND:
117
1.28k
      op = MCInst_getOperand(MI, 0);
118
1.28k
      if (EBPF_MODE(MI->csh->mode))
119
793
        push_op_mem(bpf, MCOperand_getReg(op), 0x0,
120
793
              true, true);
121
492
      else {
122
492
        op2 = MCInst_getOperand(MI, 1);
123
492
        push_op_mem(bpf, MCOperand_getReg(op),
124
492
              (uint32_t)MCOperand_getImm(op2),
125
492
              false, true);
126
492
      }
127
1.28k
      break;
128
991
    case BPF_MODE_MEM:
129
991
      if (EBPF_MODE(MI->csh->mode)) {
130
        /* ldx{w,h,b,dw} dst, [src+off] */
131
783
        push_op_reg(bpf,
132
783
              MCOperand_getReg(
133
783
                MCInst_getOperand(MI, 0)),
134
783
              CS_AC_WRITE);
135
783
        op = MCInst_getOperand(MI, 1);
136
783
        op2 = MCInst_getOperand(MI, 2);
137
783
        push_op_mem(bpf, MCOperand_getReg(op),
138
783
              (uint32_t)MCOperand_getImm(op2),
139
783
              true, false);
140
783
      } else {
141
208
        push_op_mmem(bpf,
142
208
               (uint32_t)MCOperand_getImm(
143
208
                 MCInst_getOperand(MI, 0)));
144
208
      }
145
991
      break;
146
331
    case BPF_MODE_LEN:
147
331
      push_op_ext(bpf, BPF_EXT_LEN);
148
331
      break;
149
195
    case BPF_MODE_MSH:
150
195
      op = MCInst_getOperand(MI, 0);
151
195
      push_op_msh(bpf, (uint32_t)MCOperand_getImm(op));
152
195
      break;
153
      /* case BPF_MODE_XADD: // not exists */
154
5.24k
    }
155
5.24k
    return;
156
5.24k
  }
157
17.2k
  if (BPF_CLASS(opcode) == BPF_CLASS_ST ||
158
16.3k
      BPF_CLASS(opcode) == BPF_CLASS_STX) {
159
2.95k
    if (!EBPF_MODE(MI->csh->mode)) {
160
      // cBPF has only one case - st* M[k]
161
104
      push_op_mmem(bpf, (uint32_t)MCOperand_getImm(
162
104
              MCInst_getOperand(MI, 0)));
163
104
      return;
164
104
    }
165
    /* eBPF has two cases:
166
     * - st [dst + off], src
167
     * - xadd [dst + off], src
168
     * they have same form of operands.
169
     */
170
2.84k
    op = MCInst_getOperand(MI, 0);
171
2.84k
    op2 = MCInst_getOperand(MI, 1);
172
2.84k
    push_op_mem(bpf, MCOperand_getReg(op),
173
2.84k
          (uint32_t)MCOperand_getImm(op2), true, false);
174
175
2.84k
    op = MCInst_getOperand(MI, 2);
176
2.84k
    if (MCOperand_isImm(op))
177
890
      push_op_imm(bpf, MCOperand_getImm(op), false);
178
1.95k
    else if (MCOperand_isReg(op))
179
1.95k
      push_op_reg(bpf, MCOperand_getReg(op), CS_AC_READ);
180
2.84k
    return;
181
2.95k
  }
182
183
14.3k
  {
184
14.3k
    const bool is_jmp32 = EBPF_MODE(MI->csh->mode) &&
185
10.3k
              (BPF_CLASS(opcode) == BPF_CLASS_JMP32);
186
14.3k
    if (BPF_CLASS(opcode) == BPF_CLASS_JMP || is_jmp32) {
187
22.2k
      for (size_t i = 0; i < mc_op_count; i++) {
188
16.0k
        op = MCInst_getOperand(MI, i);
189
16.0k
        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
11.1k
          if ((BPF_OP(opcode) == BPF_JUMP_JA &&
199
628
               !is_jmp32) ||
200
10.6k
              (!EBPF_MODE(MI->csh->mode) &&
201
2.06k
               i >= 1) ||
202
9.15k
              (EBPF_MODE(MI->csh->mode) &&
203
8.63k
               i == 2))
204
6.24k
            push_op_off(
205
6.24k
              bpf,
206
6.24k
              MCOperand_getImm(op),
207
6.24k
              EBPF_MODE(
208
6.24k
                MI->csh->mode));
209
4.87k
          else
210
4.87k
            push_op_imm(
211
4.87k
              bpf,
212
4.87k
              MCOperand_getImm(op),
213
4.87k
              true);
214
11.1k
        } else if (MCOperand_isReg(op)) {
215
4.91k
          push_op_reg(bpf, MCOperand_getReg(op),
216
4.91k
                CS_AC_READ);
217
4.91k
        }
218
16.0k
      }
219
6.22k
      return;
220
6.22k
    }
221
14.3k
  }
222
223
8.10k
  if (!EBPF_MODE(MI->csh->mode)) {
224
    /* In cBPF mode, all registers in operands are accessed as read */
225
5.45k
    for (size_t i = 0; i < mc_op_count; i++) {
226
2.41k
      op = MCInst_getOperand(MI, i);
227
2.41k
      if (MCOperand_isImm(op))
228
1.00k
        push_op_imm(bpf, MCOperand_getImm(op), false);
229
1.40k
      else if (MCOperand_isReg(op))
230
1.40k
        push_op_reg(bpf, MCOperand_getReg(op),
231
1.40k
              CS_AC_READ);
232
2.41k
    }
233
3.03k
    return;
234
3.03k
  }
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
5.07k
  if (mc_op_count == 1) {
248
1.80k
    op = MCInst_getOperand(MI, 0);
249
1.80k
    push_op_reg(bpf, MCOperand_getReg(op),
250
1.80k
          CS_AC_READ | CS_AC_WRITE);
251
3.27k
  } else { // if (mc_op_count == 2)
252
3.27k
    op = MCInst_getOperand(MI, 0);
253
3.27k
    push_op_reg(bpf, MCOperand_getReg(op),
254
3.27k
          CS_AC_READ | CS_AC_WRITE);
255
256
3.27k
    op = MCInst_getOperand(MI, 1);
257
3.27k
    if (MCOperand_isImm(op))
258
2.90k
      push_op_imm(bpf, MCOperand_getImm(op), false);
259
364
    else if (MCOperand_isReg(op))
260
364
      push_op_reg(bpf, MCOperand_getReg(op), CS_AC_READ);
261
3.27k
  }
262
5.07k
}
263
264
static void print_operand(MCInst *MI, struct SStream *O, const cs_bpf_op *op)
265
38.8k
{
266
38.8k
  switch (op->type) {
267
0
  case BPF_OP_INVALID:
268
0
    SStream_concat(O, "invalid");
269
0
    break;
270
14.7k
  case BPF_OP_REG:
271
14.7k
    SStream_concat(O, BPF_reg_name((csh)MI->csh, op->reg));
272
14.7k
    break;
273
10.5k
  case BPF_OP_IMM:
274
10.5k
    if (op->is_signed)
275
4.87k
      printInt32Hex(O, op->imm);
276
5.62k
    else
277
5.62k
      SStream_concat(O, "0x%" PRIx64, op->imm);
278
10.5k
    break;
279
6.24k
  case BPF_OP_OFF:
280
6.24k
    if (op->is_signed)
281
4.47k
      printInt16HexOffset(O, op->off);
282
1.76k
    else
283
1.76k
      SStream_concat(O, "+0x%" PRIx32, op->off);
284
6.24k
    break;
285
6.53k
  case BPF_OP_MEM:
286
6.53k
    SStream_concat(O, "[");
287
288
6.53k
    if (op->is_pkt && EBPF_MODE(MI->csh->mode)) {
289
1.88k
      SStream_concat(O, "skb");
290
291
1.88k
      if (op->mem.base != BPF_REG_INVALID)
292
793
        SStream_concat(O, "+%s",
293
793
                 BPF_reg_name((csh)MI->csh,
294
793
                  op->mem.base));
295
1.08k
      else {
296
1.08k
        if (op->is_signed)
297
1.08k
          printInt32HexOffset(O, op->mem.disp);
298
0
        else
299
0
          SStream_concat(O, "+0x%" PRIx32,
300
0
                   op->mem.disp);
301
1.08k
      }
302
4.65k
    } else {
303
4.65k
      if (op->mem.base != BPF_REG_INVALID)
304
4.12k
        SStream_concat(O, BPF_reg_name((csh)MI->csh,
305
4.12k
                     op->mem.base));
306
4.65k
      if (op->mem.disp != 0) {
307
3.89k
        if (op->mem.base != BPF_REG_INVALID) {
308
          // if operation is signed, then it always uses off, not k
309
3.44k
          if (op->is_signed)
310
2.95k
            printInt16HexOffset(
311
2.95k
              O, op->mem.disp);
312
490
          else if (op->is_pkt)
313
490
            SStream_concat(O, "+0x%" PRIx32,
314
490
                     op->mem.disp);
315
0
          else
316
0
            SStream_concat(O, "+0x%" PRIx16,
317
0
                     op->mem.disp);
318
3.44k
        } else
319
458
          SStream_concat(O, "0x%" PRIx32,
320
458
                   op->mem.disp);
321
3.89k
      }
322
323
4.65k
      if (op->mem.base == BPF_REG_INVALID &&
324
529
          op->mem.disp == 0)
325
71
        SStream_concat(O, "0x0");
326
4.65k
    }
327
328
6.53k
    SStream_concat(O, "]");
329
6.53k
    break;
330
312
  case BPF_OP_MMEM:
331
312
    SStream_concat(O, "m[0x%x]", op->mmem);
332
312
    break;
333
195
  case BPF_OP_MSH:
334
195
    SStream_concat(O, "4*([0x%x]&0xf)", op->msh);
335
195
    break;
336
331
  case BPF_OP_EXT:
337
331
    switch (op->ext) {
338
331
    case BPF_EXT_LEN:
339
331
      SStream_concat(O, "#len");
340
331
      break;
341
331
    }
342
331
    break;
343
38.8k
  }
344
38.8k
}
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
22.5k
{
353
22.5k
  cs_bpf bpf = { 0 };
354
355
  /* set pubOpcode as instruction id */
356
22.5k
  SStream_concat(O, BPF_insn_name((csh)MI->csh, MCInst_getOpcodePub(MI)));
357
22.5k
  convert_operands(MI, &bpf);
358
61.3k
  for (size_t i = 0; i < bpf.op_count; i++) {
359
38.8k
    if (i == 0)
360
21.6k
      SStream_concat(O, "\t");
361
17.2k
    else
362
17.2k
      SStream_concat(O, ", ");
363
38.8k
    print_operand(MI, O, &bpf.operands[i]);
364
38.8k
  }
365
366
22.5k
#ifndef CAPSTONE_DIET
367
22.5k
  if (detail_is_set(MI)) {
368
22.5k
    MI->flat_insn->detail->bpf = bpf;
369
22.5k
  }
370
22.5k
#endif
371
22.5k
}