Coverage Report

Created: 2026-06-06 06:15

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
18.6k
{
15
18.6k
  assert(bpf->op_count < 3);
16
18.6k
  return &bpf->operands[bpf->op_count++];
17
18.6k
}
18
19
static void push_op_reg(cs_bpf *bpf, bpf_op_type val, uint8_t ac_mode)
20
16.3k
{
21
16.3k
  cs_bpf_op *op = expand_bpf_operands(bpf);
22
23
16.3k
  op->type = BPF_OP_REG;
24
16.3k
  op->reg = val;
25
16.3k
  op->access = ac_mode;
26
16.3k
}
27
28
static void push_op_imm(cs_bpf *bpf, uint64_t val, const bool is_signed)
29
12.0k
{
30
12.0k
  cs_bpf_op *op = expand_bpf_operands(bpf);
31
32
12.0k
  op->type = BPF_OP_IMM;
33
12.0k
  op->imm = val;
34
12.0k
  op->is_signed = is_signed;
35
12.0k
}
36
37
static void push_op_off(cs_bpf *bpf, uint32_t val, const bool is_signed)
38
6.95k
{
39
6.95k
  cs_bpf_op *op = expand_bpf_operands(bpf);
40
41
6.95k
  op->type = BPF_OP_OFF;
42
6.95k
  op->off = val;
43
6.95k
  op->is_signed = is_signed;
44
6.95k
}
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
7.21k
{
49
7.21k
  cs_bpf_op *op = expand_bpf_operands(bpf);
50
51
7.21k
  op->type = BPF_OP_MEM;
52
7.21k
  op->mem.base = reg;
53
7.21k
  op->mem.disp = val;
54
7.21k
  op->is_signed = is_signed;
55
7.21k
  op->is_pkt = is_pkt;
56
7.21k
}
57
58
static void push_op_mmem(cs_bpf *bpf, uint32_t val)
59
928
{
60
928
  cs_bpf_op *op = expand_bpf_operands(bpf);
61
62
928
  op->type = BPF_OP_MMEM;
63
928
  op->mmem = val;
64
928
}
65
66
static void push_op_msh(cs_bpf *bpf, uint32_t val)
67
385
{
68
385
  cs_bpf_op *op = expand_bpf_operands(bpf);
69
70
385
  op->type = BPF_OP_MSH;
71
385
  op->msh = val;
72
385
}
73
74
static void push_op_ext(cs_bpf *bpf, bpf_ext_type val)
75
420
{
76
420
  cs_bpf_op *op = expand_bpf_operands(bpf);
77
78
420
  op->type = BPF_OP_EXT;
79
420
  op->ext = val;
80
420
}
81
82
static void convert_operands(MCInst *MI, cs_bpf *bpf)
83
11.0k
{
84
11.0k
  unsigned opcode = MCInst_getOpcode(MI);
85
11.0k
  unsigned mc_op_count = MCInst_getNumOperands(MI);
86
11.0k
  MCOperand *op;
87
11.0k
  MCOperand *op2;
88
89
11.0k
  bpf->op_count = 0;
90
11.0k
  if (BPF_CLASS(opcode) == BPF_CLASS_LD ||
91
8.24k
      BPF_CLASS(opcode) == BPF_CLASS_LDX) {
92
3.15k
    switch (BPF_MODE(opcode)) {
93
341
    case BPF_MODE_IMM:
94
341
      if (EBPF_MODE(MI->csh->mode)) {
95
17
        push_op_reg(bpf,
96
17
              MCOperand_getReg(
97
17
                MCInst_getOperand(MI, 0)),
98
17
              CS_AC_WRITE);
99
17
        push_op_imm(bpf,
100
17
              MCOperand_getImm(
101
17
                MCInst_getOperand(MI, 1)),
102
17
              false);
103
324
      } else {
104
324
        push_op_imm(bpf,
105
324
              MCOperand_getImm(
106
324
                MCInst_getOperand(MI, 0)),
107
324
              false);
108
324
      }
109
341
      break;
110
1.22k
    case BPF_MODE_ABS:
111
1.22k
      op = MCInst_getOperand(MI, 0);
112
1.22k
      push_op_mem(bpf, BPF_REG_INVALID,
113
1.22k
            (uint32_t)MCOperand_getImm(op),
114
1.22k
            EBPF_MODE(MI->csh->mode), true);
115
1.22k
      break;
116
974
    case BPF_MODE_IND:
117
974
      op = MCInst_getOperand(MI, 0);
118
974
      if (EBPF_MODE(MI->csh->mode))
119
494
        push_op_mem(bpf, MCOperand_getReg(op), 0x0,
120
494
              true, true);
121
480
      else {
122
480
        op2 = MCInst_getOperand(MI, 1);
123
480
        push_op_mem(bpf, MCOperand_getReg(op),
124
480
              (uint32_t)MCOperand_getImm(op2),
125
480
              false, true);
126
480
      }
127
974
      break;
128
231
    case BPF_MODE_MEM:
129
231
      if (EBPF_MODE(MI->csh->mode)) {
130
        /* ldx{w,h,b,dw} dst, [src+off] */
131
150
        push_op_reg(bpf,
132
150
              MCOperand_getReg(
133
150
                MCInst_getOperand(MI, 0)),
134
150
              CS_AC_WRITE);
135
150
        op = MCInst_getOperand(MI, 1);
136
150
        op2 = MCInst_getOperand(MI, 2);
137
150
        push_op_mem(bpf, MCOperand_getReg(op),
138
150
              (uint32_t)MCOperand_getImm(op2),
139
150
              true, false);
140
150
      } else {
141
81
        push_op_mmem(bpf,
142
81
               (uint32_t)MCOperand_getImm(
143
81
                 MCInst_getOperand(MI, 0)));
144
81
      }
145
231
      break;
146
209
    case BPF_MODE_LEN:
147
209
      push_op_ext(bpf, BPF_EXT_LEN);
148
209
      break;
149
171
    case BPF_MODE_MSH:
150
171
      op = MCInst_getOperand(MI, 0);
151
171
      push_op_msh(bpf, (uint32_t)MCOperand_getImm(op));
152
171
      break;
153
      /* case BPF_MODE_XADD: // not exists */
154
3.15k
    }
155
3.15k
    return;
156
3.15k
  }
157
7.86k
  if (BPF_CLASS(opcode) == BPF_CLASS_ST ||
158
7.40k
      BPF_CLASS(opcode) == BPF_CLASS_STX) {
159
926
    if (!EBPF_MODE(MI->csh->mode)) {
160
      // cBPF has only one case - st* M[k]
161
90
      push_op_mmem(bpf, (uint32_t)MCOperand_getImm(
162
90
              MCInst_getOperand(MI, 0)));
163
90
      return;
164
90
    }
165
    /* eBPF has two cases:
166
     * - st [dst + off], src
167
     * - xadd [dst + off], src
168
     * they have same form of operands.
169
     */
170
836
    op = MCInst_getOperand(MI, 0);
171
836
    op2 = MCInst_getOperand(MI, 1);
172
836
    push_op_mem(bpf, MCOperand_getReg(op),
173
836
          (uint32_t)MCOperand_getImm(op2), true, false);
174
175
836
    op = MCInst_getOperand(MI, 2);
176
836
    if (MCOperand_isImm(op))
177
444
      push_op_imm(bpf, MCOperand_getImm(op), false);
178
392
    else if (MCOperand_isReg(op))
179
392
      push_op_reg(bpf, MCOperand_getReg(op), CS_AC_READ);
180
836
    return;
181
926
  }
182
183
6.93k
  {
184
6.93k
    const bool is_jmp32 = EBPF_MODE(MI->csh->mode) &&
185
4.92k
              (BPF_CLASS(opcode) == BPF_CLASS_JMP32);
186
6.93k
    if (BPF_CLASS(opcode) == BPF_CLASS_JMP || is_jmp32) {
187
11.6k
      for (size_t i = 0; i < mc_op_count; i++) {
188
8.30k
        op = MCInst_getOperand(MI, i);
189
8.30k
        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
5.78k
          if ((BPF_OP(opcode) == BPF_JUMP_JA &&
199
350
               !is_jmp32) ||
200
5.50k
              (!EBPF_MODE(MI->csh->mode) &&
201
1.41k
               i >= 1) ||
202
4.23k
              (EBPF_MODE(MI->csh->mode) &&
203
4.09k
               i == 2))
204
3.50k
            push_op_off(
205
3.50k
              bpf,
206
3.50k
              MCOperand_getImm(op),
207
3.50k
              EBPF_MODE(
208
3.50k
                MI->csh->mode));
209
2.27k
          else
210
2.27k
            push_op_imm(
211
2.27k
              bpf,
212
2.27k
              MCOperand_getImm(op),
213
2.27k
              true);
214
5.78k
        } else if (MCOperand_isReg(op)) {
215
2.52k
          push_op_reg(bpf, MCOperand_getReg(op),
216
2.52k
                CS_AC_READ);
217
2.52k
        }
218
8.30k
      }
219
3.34k
      return;
220
3.34k
    }
221
6.93k
  }
222
223
3.59k
  if (!EBPF_MODE(MI->csh->mode)) {
224
    /* In cBPF mode, all registers in operands are accessed as read */
225
2.51k
    for (size_t i = 0; i < mc_op_count; i++) {
226
1.20k
      op = MCInst_getOperand(MI, i);
227
1.20k
      if (MCOperand_isImm(op))
228
397
        push_op_imm(bpf, MCOperand_getImm(op), false);
229
807
      else if (MCOperand_isReg(op))
230
807
        push_op_reg(bpf, MCOperand_getReg(op),
231
807
              CS_AC_READ);
232
1.20k
    }
233
1.30k
    return;
234
1.30k
  }
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
2.28k
  if (mc_op_count == 1) {
248
540
    op = MCInst_getOperand(MI, 0);
249
540
    push_op_reg(bpf, MCOperand_getReg(op),
250
540
          CS_AC_READ | CS_AC_WRITE);
251
1.74k
  } else { // if (mc_op_count == 2)
252
1.74k
    op = MCInst_getOperand(MI, 0);
253
1.74k
    push_op_reg(bpf, MCOperand_getReg(op),
254
1.74k
          CS_AC_READ | CS_AC_WRITE);
255
256
1.74k
    op = MCInst_getOperand(MI, 1);
257
1.74k
    if (MCOperand_isImm(op))
258
1.45k
      push_op_imm(bpf, MCOperand_getImm(op), false);
259
283
    else if (MCOperand_isReg(op))
260
283
      push_op_reg(bpf, MCOperand_getReg(op), CS_AC_READ);
261
1.74k
  }
262
2.28k
}
263
264
static void print_operand(MCInst *MI, struct SStream *O, const cs_bpf_op *op)
265
18.6k
{
266
18.6k
  switch (op->type) {
267
0
  case BPF_OP_INVALID:
268
0
    SStream_concat(O, "invalid");
269
0
    break;
270
6.45k
  case BPF_OP_REG:
271
6.45k
    SStream_concat(O, BPF_reg_name((csh)MI->csh, op->reg));
272
6.45k
    break;
273
4.91k
  case BPF_OP_IMM:
274
4.91k
    if (op->is_signed)
275
2.27k
      printInt32Hex(O, op->imm);
276
2.64k
    else
277
2.64k
      SStream_concat(O, "0x%" PRIx64, op->imm);
278
4.91k
    break;
279
3.50k
  case BPF_OP_OFF:
280
3.50k
    if (op->is_signed)
281
2.16k
      printInt16HexOffset(O, op->off);
282
1.33k
    else
283
1.33k
      SStream_concat(O, "+0x%" PRIx32, op->off);
284
3.50k
    break;
285
3.18k
  case BPF_OP_MEM:
286
3.18k
    SStream_concat(O, "[");
287
288
3.18k
    if (op->is_pkt && EBPF_MODE(MI->csh->mode)) {
289
1.37k
      SStream_concat(O, "skb");
290
291
1.37k
      if (op->mem.base != BPF_REG_INVALID)
292
494
        SStream_concat(O, "+%s",
293
494
                 BPF_reg_name((csh)MI->csh,
294
494
                  op->mem.base));
295
877
      else {
296
877
        if (op->is_signed)
297
877
          printInt32HexOffset(O, op->mem.disp);
298
0
        else
299
0
          SStream_concat(O, "+0x%" PRIx32,
300
0
                   op->mem.disp);
301
877
      }
302
1.81k
    } else {
303
1.81k
      if (op->mem.base != BPF_REG_INVALID)
304
1.46k
        SStream_concat(O, BPF_reg_name((csh)MI->csh,
305
1.46k
                     op->mem.base));
306
1.81k
      if (op->mem.disp != 0) {
307
1.68k
        if (op->mem.base != BPF_REG_INVALID) {
308
          // if operation is signed, then it always uses off, not k
309
1.35k
          if (op->is_signed)
310
876
            printInt16HexOffset(
311
876
              O, op->mem.disp);
312
478
          else if (op->is_pkt)
313
478
            SStream_concat(O, "+0x%" PRIx32,
314
478
                     op->mem.disp);
315
0
          else
316
0
            SStream_concat(O, "+0x%" PRIx16,
317
0
                     op->mem.disp);
318
1.35k
        } else
319
331
          SStream_concat(O, "0x%" PRIx32,
320
331
                   op->mem.disp);
321
1.68k
      }
322
323
1.81k
      if (op->mem.base == BPF_REG_INVALID &&
324
350
          op->mem.disp == 0)
325
19
        SStream_concat(O, "0x0");
326
1.81k
    }
327
328
3.18k
    SStream_concat(O, "]");
329
3.18k
    break;
330
171
  case BPF_OP_MMEM:
331
171
    SStream_concat(O, "m[0x%x]", op->mmem);
332
171
    break;
333
171
  case BPF_OP_MSH:
334
171
    SStream_concat(O, "4*([0x%x]&0xf)", op->msh);
335
171
    break;
336
209
  case BPF_OP_EXT:
337
209
    switch (op->ext) {
338
209
    case BPF_EXT_LEN:
339
209
      SStream_concat(O, "#len");
340
209
      break;
341
209
    }
342
209
    break;
343
18.6k
  }
344
18.6k
}
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
28.0k
{
353
28.0k
  cs_bpf bpf = { 0 };
354
355
  /* set pubOpcode as instruction id */
356
28.0k
  SStream_concat(O, BPF_insn_name((csh)MI->csh, MCInst_getOpcodePub(MI)));
357
28.0k
  convert_operands(MI, &bpf);
358
72.4k
  for (size_t i = 0; i < bpf.op_count; i++) {
359
44.3k
    if (i == 0)
360
26.5k
      SStream_concat(O, "\t");
361
17.7k
    else
362
17.7k
      SStream_concat(O, ", ");
363
44.3k
    print_operand(MI, O, &bpf.operands[i]);
364
44.3k
  }
365
366
28.0k
#ifndef CAPSTONE_DIET
367
28.0k
  if (detail_is_set(MI)) {
368
28.0k
    MI->flat_insn->detail->bpf = bpf;
369
28.0k
  }
370
28.0k
#endif
371
28.0k
}