Coverage Report

Created: 2025-10-10 06:20

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
11.0k
{
15
11.0k
  assert(bpf->op_count < 3);
16
11.0k
  return &bpf->operands[bpf->op_count++];
17
11.0k
}
18
19
static void push_op_reg(cs_bpf *bpf, bpf_op_type val, uint8_t ac_mode)
20
3.83k
{
21
3.83k
  cs_bpf_op *op = expand_bpf_operands(bpf);
22
23
3.83k
  op->type = BPF_OP_REG;
24
3.83k
  op->reg = val;
25
3.83k
  op->access = ac_mode;
26
3.83k
}
27
28
static void push_op_imm(cs_bpf *bpf, uint64_t val, const bool is_signed)
29
3.01k
{
30
3.01k
  cs_bpf_op *op = expand_bpf_operands(bpf);
31
32
3.01k
  op->type = BPF_OP_IMM;
33
3.01k
  op->imm = val;
34
3.01k
  op->is_signed = is_signed;
35
3.01k
}
36
37
static void push_op_off(cs_bpf *bpf, uint32_t val, const bool is_signed)
38
2.07k
{
39
2.07k
  cs_bpf_op *op = expand_bpf_operands(bpf);
40
41
2.07k
  op->type = BPF_OP_OFF;
42
2.07k
  op->off = val;
43
2.07k
  op->is_signed = is_signed;
44
2.07k
}
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
1.92k
{
49
1.92k
  cs_bpf_op *op = expand_bpf_operands(bpf);
50
51
1.92k
  op->type = BPF_OP_MEM;
52
1.92k
  op->mem.base = reg;
53
1.92k
  op->mem.disp = val;
54
1.92k
  op->is_signed = is_signed;
55
1.92k
  op->is_pkt = is_pkt;
56
1.92k
}
57
58
static void push_op_mmem(cs_bpf *bpf, uint32_t val)
59
17
{
60
17
  cs_bpf_op *op = expand_bpf_operands(bpf);
61
62
17
  op->type = BPF_OP_MMEM;
63
17
  op->mmem = val;
64
17
}
65
66
static void push_op_msh(cs_bpf *bpf, uint32_t val)
67
52
{
68
52
  cs_bpf_op *op = expand_bpf_operands(bpf);
69
70
52
  op->type = BPF_OP_MSH;
71
52
  op->msh = val;
72
52
}
73
74
static void push_op_ext(cs_bpf *bpf, bpf_ext_type val)
75
165
{
76
165
  cs_bpf_op *op = expand_bpf_operands(bpf);
77
78
165
  op->type = BPF_OP_EXT;
79
165
  op->ext = val;
80
165
}
81
82
static void convert_operands(MCInst *MI, cs_bpf *bpf)
83
6.36k
{
84
6.36k
  unsigned opcode = MCInst_getOpcode(MI);
85
6.36k
  unsigned mc_op_count = MCInst_getNumOperands(MI);
86
6.36k
  MCOperand *op;
87
6.36k
  MCOperand *op2;
88
89
6.36k
  bpf->op_count = 0;
90
6.36k
  if (BPF_CLASS(opcode) == BPF_CLASS_LD ||
91
5.15k
      BPF_CLASS(opcode) == BPF_CLASS_LDX) {
92
1.77k
    switch (BPF_MODE(opcode)) {
93
246
    case BPF_MODE_IMM:
94
246
      if (EBPF_MODE(MI->csh->mode)) {
95
7
        push_op_reg(bpf,
96
7
              MCOperand_getReg(
97
7
                MCInst_getOperand(MI, 0)),
98
7
              CS_AC_WRITE);
99
7
        push_op_imm(bpf,
100
7
              MCOperand_getImm(
101
7
                MCInst_getOperand(MI, 1)),
102
7
              false);
103
239
      } else {
104
239
        push_op_imm(bpf,
105
239
              MCOperand_getImm(
106
239
                MCInst_getOperand(MI, 0)),
107
239
              false);
108
239
      }
109
246
      break;
110
707
    case BPF_MODE_ABS:
111
707
      op = MCInst_getOperand(MI, 0);
112
707
      push_op_mem(bpf, BPF_REG_INVALID,
113
707
            (uint32_t)MCOperand_getImm(op),
114
707
            EBPF_MODE(MI->csh->mode), true);
115
707
      break;
116
225
    case BPF_MODE_IND:
117
225
      op = MCInst_getOperand(MI, 0);
118
225
      if (EBPF_MODE(MI->csh->mode))
119
57
        push_op_mem(bpf, MCOperand_getReg(op), 0x0,
120
57
              true, true);
121
168
      else {
122
168
        op2 = MCInst_getOperand(MI, 1);
123
168
        push_op_mem(bpf, MCOperand_getReg(op),
124
168
              (uint32_t)MCOperand_getImm(op2),
125
168
              false, true);
126
168
      }
127
225
      break;
128
377
    case BPF_MODE_MEM:
129
377
      if (EBPF_MODE(MI->csh->mode)) {
130
        /* ldx{w,h,b,dw} dst, [src+off] */
131
376
        push_op_reg(bpf,
132
376
              MCOperand_getReg(
133
376
                MCInst_getOperand(MI, 0)),
134
376
              CS_AC_WRITE);
135
376
        op = MCInst_getOperand(MI, 1);
136
376
        op2 = MCInst_getOperand(MI, 2);
137
376
        push_op_mem(bpf, MCOperand_getReg(op),
138
376
              (uint32_t)MCOperand_getImm(op2),
139
376
              true, false);
140
376
      } else {
141
1
        push_op_mmem(bpf,
142
1
               (uint32_t)MCOperand_getImm(
143
1
                 MCInst_getOperand(MI, 0)));
144
1
      }
145
377
      break;
146
165
    case BPF_MODE_LEN:
147
165
      push_op_ext(bpf, BPF_EXT_LEN);
148
165
      break;
149
52
    case BPF_MODE_MSH:
150
52
      op = MCInst_getOperand(MI, 0);
151
52
      push_op_msh(bpf, (uint32_t)MCOperand_getImm(op));
152
52
      break;
153
      /* case BPF_MODE_XADD: // not exists */
154
1.77k
    }
155
1.77k
    return;
156
1.77k
  }
157
4.59k
  if (BPF_CLASS(opcode) == BPF_CLASS_ST ||
158
4.33k
      BPF_CLASS(opcode) == BPF_CLASS_STX) {
159
633
    if (!EBPF_MODE(MI->csh->mode)) {
160
      // cBPF has only one case - st* M[k]
161
16
      push_op_mmem(bpf, (uint32_t)MCOperand_getImm(
162
16
              MCInst_getOperand(MI, 0)));
163
16
      return;
164
16
    }
165
    /* eBPF has two cases:
166
     * - st [dst + off], src
167
     * - xadd [dst + off], src
168
     * they have same form of operands.
169
     */
170
617
    op = MCInst_getOperand(MI, 0);
171
617
    op2 = MCInst_getOperand(MI, 1);
172
617
    push_op_mem(bpf, MCOperand_getReg(op),
173
617
          (uint32_t)MCOperand_getImm(op2), true, false);
174
175
617
    op = MCInst_getOperand(MI, 2);
176
617
    if (MCOperand_isImm(op))
177
259
      push_op_imm(bpf, MCOperand_getImm(op), false);
178
358
    else if (MCOperand_isReg(op))
179
358
      push_op_reg(bpf, MCOperand_getReg(op), CS_AC_READ);
180
617
    return;
181
633
  }
182
183
3.96k
  {
184
3.96k
    const bool is_jmp32 = EBPF_MODE(MI->csh->mode) &&
185
2.48k
              (BPF_CLASS(opcode) == BPF_CLASS_JMP32);
186
3.96k
    if (BPF_CLASS(opcode) == BPF_CLASS_JMP || is_jmp32) {
187
6.58k
      for (size_t i = 0; i < mc_op_count; i++) {
188
4.74k
        op = MCInst_getOperand(MI, i);
189
4.74k
        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
3.40k
          if ((BPF_OP(opcode) == BPF_JUMP_JA &&
199
285
               !is_jmp32) ||
200
3.13k
              (!EBPF_MODE(MI->csh->mode) &&
201
872
               i >= 1) ||
202
2.42k
              (EBPF_MODE(MI->csh->mode) &&
203
2.26k
               i == 2))
204
2.07k
            push_op_off(
205
2.07k
              bpf,
206
2.07k
              MCOperand_getImm(op),
207
2.07k
              EBPF_MODE(
208
2.07k
                MI->csh->mode));
209
1.32k
          else
210
1.32k
            push_op_imm(
211
1.32k
              bpf,
212
1.32k
              MCOperand_getImm(op),
213
1.32k
              true);
214
3.40k
        } else if (MCOperand_isReg(op)) {
215
1.34k
          push_op_reg(bpf, MCOperand_getReg(op),
216
1.34k
                CS_AC_READ);
217
1.34k
        }
218
4.74k
      }
219
1.83k
      return;
220
1.83k
    }
221
3.96k
  }
222
223
2.12k
  if (!EBPF_MODE(MI->csh->mode)) {
224
    /* In cBPF mode, all registers in operands are accessed as read */
225
1.87k
    for (size_t i = 0; i < mc_op_count; i++) {
226
884
      op = MCInst_getOperand(MI, i);
227
884
      if (MCOperand_isImm(op))
228
397
        push_op_imm(bpf, MCOperand_getImm(op), false);
229
487
      else if (MCOperand_isReg(op))
230
487
        push_op_reg(bpf, MCOperand_getReg(op),
231
487
              CS_AC_READ);
232
884
    }
233
995
    return;
234
995
  }
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
1.12k
  if (mc_op_count == 1) {
248
206
    op = MCInst_getOperand(MI, 0);
249
206
    push_op_reg(bpf, MCOperand_getReg(op),
250
206
          CS_AC_READ | CS_AC_WRITE);
251
923
  } else { // if (mc_op_count == 2)
252
923
    op = MCInst_getOperand(MI, 0);
253
923
    push_op_reg(bpf, MCOperand_getReg(op),
254
923
          CS_AC_READ | CS_AC_WRITE);
255
256
923
    op = MCInst_getOperand(MI, 1);
257
923
    if (MCOperand_isImm(op))
258
787
      push_op_imm(bpf, MCOperand_getImm(op), false);
259
136
    else if (MCOperand_isReg(op))
260
136
      push_op_reg(bpf, MCOperand_getReg(op), CS_AC_READ);
261
923
  }
262
1.12k
}
263
264
static void print_operand(MCInst *MI, struct SStream *O, const cs_bpf_op *op)
265
11.0k
{
266
11.0k
  switch (op->type) {
267
0
  case BPF_OP_INVALID:
268
0
    SStream_concat(O, "invalid");
269
0
    break;
270
3.83k
  case BPF_OP_REG:
271
3.83k
    SStream_concat(O, BPF_reg_name((csh)MI->csh, op->reg));
272
3.83k
    break;
273
3.01k
  case BPF_OP_IMM:
274
3.01k
    if (op->is_signed)
275
1.32k
      printInt32Hex(O, op->imm);
276
1.68k
    else
277
1.68k
      SStream_concat(O, "0x%" PRIx64, op->imm);
278
3.01k
    break;
279
2.07k
  case BPF_OP_OFF:
280
2.07k
    if (op->is_signed)
281
1.23k
      printInt16HexOffset(O, op->off);
282
837
    else
283
837
      SStream_concat(O, "+0x%" PRIx32, op->off);
284
2.07k
    break;
285
1.92k
  case BPF_OP_MEM:
286
1.92k
    SStream_concat(O, "[");
287
288
1.92k
    if (op->is_pkt && EBPF_MODE(MI->csh->mode)) {
289
510
      SStream_concat(O, "skb");
290
291
510
      if (op->mem.base != BPF_REG_INVALID)
292
57
        SStream_concat(O, "+%s",
293
57
                 BPF_reg_name((csh)MI->csh,
294
57
                  op->mem.base));
295
453
      else {
296
453
        if (op->is_signed)
297
453
          printInt32HexOffset(O, op->mem.disp);
298
0
        else
299
0
          SStream_concat(O, "+0x%" PRIx32,
300
0
                   op->mem.disp);
301
453
      }
302
1.41k
    } else {
303
1.41k
      if (op->mem.base != BPF_REG_INVALID)
304
1.16k
        SStream_concat(O, BPF_reg_name((csh)MI->csh,
305
1.16k
                     op->mem.base));
306
1.41k
      if (op->mem.disp != 0) {
307
1.31k
        if (op->mem.base != BPF_REG_INVALID) {
308
          // if operation is signed, then it always uses off, not k
309
1.11k
          if (op->is_signed)
310
948
            printInt16HexOffset(
311
948
              O, op->mem.disp);
312
168
          else if (op->is_pkt)
313
168
            SStream_concat(O, "+0x%" PRIx32,
314
168
                     op->mem.disp);
315
0
          else
316
0
            SStream_concat(O, "+0x%" PRIx16,
317
0
                     op->mem.disp);
318
1.11k
        } else
319
203
          SStream_concat(O, "0x%" PRIx32,
320
203
                   op->mem.disp);
321
1.31k
      }
322
323
1.41k
      if (op->mem.base == BPF_REG_INVALID &&
324
254
          op->mem.disp == 0)
325
51
        SStream_concat(O, "0x0");
326
1.41k
    }
327
328
1.92k
    SStream_concat(O, "]");
329
1.92k
    break;
330
17
  case BPF_OP_MMEM:
331
17
    SStream_concat(O, "m[0x%x]", op->mmem);
332
17
    break;
333
52
  case BPF_OP_MSH:
334
52
    SStream_concat(O, "4*([0x%x]&0xf)", op->msh);
335
52
    break;
336
165
  case BPF_OP_EXT:
337
165
    switch (op->ext) {
338
165
    case BPF_EXT_LEN:
339
165
      SStream_concat(O, "#len");
340
165
      break;
341
165
    }
342
165
    break;
343
11.0k
  }
344
11.0k
}
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
6.36k
{
353
6.36k
  cs_bpf bpf = { 0 };
354
355
  /* set pubOpcode as instruction id */
356
6.36k
  SStream_concat(O, BPF_insn_name((csh)MI->csh, MCInst_getOpcodePub(MI)));
357
6.36k
  convert_operands(MI, &bpf);
358
17.4k
  for (size_t i = 0; i < bpf.op_count; i++) {
359
11.0k
    if (i == 0)
360
6.25k
      SStream_concat(O, "\t");
361
4.83k
    else
362
4.83k
      SStream_concat(O, ", ");
363
11.0k
    print_operand(MI, O, &bpf.operands[i]);
364
11.0k
  }
365
366
6.36k
#ifndef CAPSTONE_DIET
367
6.36k
  if (detail_is_set(MI)) {
368
6.36k
    MI->flat_insn->detail->bpf = bpf;
369
6.36k
  }
370
6.36k
#endif
371
6.36k
}