Coverage Report

Created: 2026-05-30 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
29.2k
{
15
29.2k
  assert(bpf->op_count < 3);
16
29.2k
  return &bpf->operands[bpf->op_count++];
17
29.2k
}
18
19
static void push_op_reg(cs_bpf *bpf, bpf_op_type val, uint8_t ac_mode)
20
11.3k
{
21
11.3k
  cs_bpf_op *op = expand_bpf_operands(bpf);
22
23
11.3k
  op->type = BPF_OP_REG;
24
11.3k
  op->reg = val;
25
11.3k
  op->access = ac_mode;
26
11.3k
}
27
28
static void push_op_imm(cs_bpf *bpf, uint64_t val, const bool is_signed)
29
7.45k
{
30
7.45k
  cs_bpf_op *op = expand_bpf_operands(bpf);
31
32
7.45k
  op->type = BPF_OP_IMM;
33
7.45k
  op->imm = val;
34
7.45k
  op->is_signed = is_signed;
35
7.45k
}
36
37
static void push_op_off(cs_bpf *bpf, uint32_t val, const bool is_signed)
38
5.38k
{
39
5.38k
  cs_bpf_op *op = expand_bpf_operands(bpf);
40
41
5.38k
  op->type = BPF_OP_OFF;
42
5.38k
  op->off = val;
43
5.38k
  op->is_signed = is_signed;
44
5.38k
}
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
4.53k
{
49
4.53k
  cs_bpf_op *op = expand_bpf_operands(bpf);
50
51
4.53k
  op->type = BPF_OP_MEM;
52
4.53k
  op->mem.base = reg;
53
4.53k
  op->mem.disp = val;
54
4.53k
  op->is_signed = is_signed;
55
4.53k
  op->is_pkt = is_pkt;
56
4.53k
}
57
58
static void push_op_mmem(cs_bpf *bpf, uint32_t val)
59
261
{
60
261
  cs_bpf_op *op = expand_bpf_operands(bpf);
61
62
261
  op->type = BPF_OP_MMEM;
63
261
  op->mmem = val;
64
261
}
65
66
static void push_op_msh(cs_bpf *bpf, uint32_t val)
67
212
{
68
212
  cs_bpf_op *op = expand_bpf_operands(bpf);
69
70
212
  op->type = BPF_OP_MSH;
71
212
  op->msh = val;
72
212
}
73
74
static void push_op_ext(cs_bpf *bpf, bpf_ext_type val)
75
68
{
76
68
  cs_bpf_op *op = expand_bpf_operands(bpf);
77
78
68
  op->type = BPF_OP_EXT;
79
68
  op->ext = val;
80
68
}
81
82
static void convert_operands(MCInst *MI, cs_bpf *bpf)
83
16.4k
{
84
16.4k
  unsigned opcode = MCInst_getOpcode(MI);
85
16.4k
  unsigned mc_op_count = MCInst_getNumOperands(MI);
86
16.4k
  MCOperand *op;
87
16.4k
  MCOperand *op2;
88
89
16.4k
  bpf->op_count = 0;
90
16.4k
  if (BPF_CLASS(opcode) == BPF_CLASS_LD ||
91
13.3k
      BPF_CLASS(opcode) == BPF_CLASS_LDX) {
92
4.53k
    switch (BPF_MODE(opcode)) {
93
618
    case BPF_MODE_IMM:
94
618
      if (EBPF_MODE(MI->csh->mode)) {
95
82
        push_op_reg(bpf,
96
82
              MCOperand_getReg(
97
82
                MCInst_getOperand(MI, 0)),
98
82
              CS_AC_WRITE);
99
82
        push_op_imm(bpf,
100
82
              MCOperand_getImm(
101
82
                MCInst_getOperand(MI, 1)),
102
82
              false);
103
536
      } else {
104
536
        push_op_imm(bpf,
105
536
              MCOperand_getImm(
106
536
                MCInst_getOperand(MI, 0)),
107
536
              false);
108
536
      }
109
618
      break;
110
1.44k
    case BPF_MODE_ABS:
111
1.44k
      op = MCInst_getOperand(MI, 0);
112
1.44k
      push_op_mem(bpf, BPF_REG_INVALID,
113
1.44k
            (uint32_t)MCOperand_getImm(op),
114
1.44k
            EBPF_MODE(MI->csh->mode), true);
115
1.44k
      break;
116
998
    case BPF_MODE_IND:
117
998
      op = MCInst_getOperand(MI, 0);
118
998
      if (EBPF_MODE(MI->csh->mode))
119
496
        push_op_mem(bpf, MCOperand_getReg(op), 0x0,
120
496
              true, true);
121
502
      else {
122
502
        op2 = MCInst_getOperand(MI, 1);
123
502
        push_op_mem(bpf, MCOperand_getReg(op),
124
502
              (uint32_t)MCOperand_getImm(op2),
125
502
              false, true);
126
502
      }
127
998
      break;
128
1.19k
    case BPF_MODE_MEM:
129
1.19k
      if (EBPF_MODE(MI->csh->mode)) {
130
        /* ldx{w,h,b,dw} dst, [src+off] */
131
1.01k
        push_op_reg(bpf,
132
1.01k
              MCOperand_getReg(
133
1.01k
                MCInst_getOperand(MI, 0)),
134
1.01k
              CS_AC_WRITE);
135
1.01k
        op = MCInst_getOperand(MI, 1);
136
1.01k
        op2 = MCInst_getOperand(MI, 2);
137
1.01k
        push_op_mem(bpf, MCOperand_getReg(op),
138
1.01k
              (uint32_t)MCOperand_getImm(op2),
139
1.01k
              true, false);
140
1.01k
      } else {
141
183
        push_op_mmem(bpf,
142
183
               (uint32_t)MCOperand_getImm(
143
183
                 MCInst_getOperand(MI, 0)));
144
183
      }
145
1.19k
      break;
146
68
    case BPF_MODE_LEN:
147
68
      push_op_ext(bpf, BPF_EXT_LEN);
148
68
      break;
149
212
    case BPF_MODE_MSH:
150
212
      op = MCInst_getOperand(MI, 0);
151
212
      push_op_msh(bpf, (uint32_t)MCOperand_getImm(op));
152
212
      break;
153
      /* case BPF_MODE_XADD: // not exists */
154
4.53k
    }
155
4.53k
    return;
156
4.53k
  }
157
11.8k
  if (BPF_CLASS(opcode) == BPF_CLASS_ST ||
158
11.3k
      BPF_CLASS(opcode) == BPF_CLASS_STX) {
159
1.15k
    if (!EBPF_MODE(MI->csh->mode)) {
160
      // cBPF has only one case - st* M[k]
161
78
      push_op_mmem(bpf, (uint32_t)MCOperand_getImm(
162
78
              MCInst_getOperand(MI, 0)));
163
78
      return;
164
78
    }
165
    /* eBPF has two cases:
166
     * - st [dst + off], src
167
     * - xadd [dst + off], src
168
     * they have same form of operands.
169
     */
170
1.08k
    op = MCInst_getOperand(MI, 0);
171
1.08k
    op2 = MCInst_getOperand(MI, 1);
172
1.08k
    push_op_mem(bpf, MCOperand_getReg(op),
173
1.08k
          (uint32_t)MCOperand_getImm(op2), true, false);
174
175
1.08k
    op = MCInst_getOperand(MI, 2);
176
1.08k
    if (MCOperand_isImm(op))
177
505
      push_op_imm(bpf, MCOperand_getImm(op), false);
178
575
    else if (MCOperand_isReg(op))
179
575
      push_op_reg(bpf, MCOperand_getReg(op), CS_AC_READ);
180
1.08k
    return;
181
1.15k
  }
182
183
10.7k
  {
184
10.7k
    const bool is_jmp32 = EBPF_MODE(MI->csh->mode) &&
185
7.54k
              (BPF_CLASS(opcode) == BPF_CLASS_JMP32);
186
10.7k
    if (BPF_CLASS(opcode) == BPF_CLASS_JMP || is_jmp32) {
187
17.9k
      for (size_t i = 0; i < mc_op_count; i++) {
188
13.0k
        op = MCInst_getOperand(MI, i);
189
13.0k
        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
8.72k
          if ((BPF_OP(opcode) == BPF_JUMP_JA &&
199
436
               !is_jmp32) ||
200
8.43k
              (!EBPF_MODE(MI->csh->mode) &&
201
1.98k
               i >= 1) ||
202
6.59k
              (EBPF_MODE(MI->csh->mode) &&
203
6.44k
               i == 2))
204
5.38k
            push_op_off(
205
5.38k
              bpf,
206
5.38k
              MCOperand_getImm(op),
207
5.38k
              EBPF_MODE(
208
5.38k
                MI->csh->mode));
209
3.34k
          else
210
3.34k
            push_op_imm(
211
3.34k
              bpf,
212
3.34k
              MCOperand_getImm(op),
213
3.34k
              true);
214
8.72k
        } else if (MCOperand_isReg(op)) {
215
4.30k
          push_op_reg(bpf, MCOperand_getReg(op),
216
4.30k
                CS_AC_READ);
217
4.30k
        }
218
13.0k
      }
219
4.95k
      return;
220
4.95k
    }
221
10.7k
  }
222
223
5.77k
  if (!EBPF_MODE(MI->csh->mode)) {
224
    /* In cBPF mode, all registers in operands are accessed as read */
225
4.13k
    for (size_t i = 0; i < mc_op_count; i++) {
226
1.92k
      op = MCInst_getOperand(MI, i);
227
1.92k
      if (MCOperand_isImm(op))
228
425
        push_op_imm(bpf, MCOperand_getImm(op), false);
229
1.49k
      else if (MCOperand_isReg(op))
230
1.49k
        push_op_reg(bpf, MCOperand_getReg(op),
231
1.49k
              CS_AC_READ);
232
1.92k
    }
233
2.20k
    return;
234
2.20k
  }
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
3.56k
  if (mc_op_count == 1) {
248
702
    op = MCInst_getOperand(MI, 0);
249
702
    push_op_reg(bpf, MCOperand_getReg(op),
250
702
          CS_AC_READ | CS_AC_WRITE);
251
2.86k
  } else { // if (mc_op_count == 2)
252
2.86k
    op = MCInst_getOperand(MI, 0);
253
2.86k
    push_op_reg(bpf, MCOperand_getReg(op),
254
2.86k
          CS_AC_READ | CS_AC_WRITE);
255
256
2.86k
    op = MCInst_getOperand(MI, 1);
257
2.86k
    if (MCOperand_isImm(op))
258
2.57k
      push_op_imm(bpf, MCOperand_getImm(op), false);
259
296
    else if (MCOperand_isReg(op))
260
296
      push_op_reg(bpf, MCOperand_getReg(op), CS_AC_READ);
261
2.86k
  }
262
3.56k
}
263
264
static void print_operand(MCInst *MI, struct SStream *O, const cs_bpf_op *op)
265
29.2k
{
266
29.2k
  switch (op->type) {
267
0
  case BPF_OP_INVALID:
268
0
    SStream_concat(O, "invalid");
269
0
    break;
270
11.3k
  case BPF_OP_REG:
271
11.3k
    SStream_concat(O, BPF_reg_name((csh)MI->csh, op->reg));
272
11.3k
    break;
273
7.45k
  case BPF_OP_IMM:
274
7.45k
    if (op->is_signed)
275
3.34k
      printInt32Hex(O, op->imm);
276
4.11k
    else
277
4.11k
      SStream_concat(O, "0x%" PRIx64, op->imm);
278
7.45k
    break;
279
5.38k
  case BPF_OP_OFF:
280
5.38k
    if (op->is_signed)
281
3.48k
      printInt16HexOffset(O, op->off);
282
1.90k
    else
283
1.90k
      SStream_concat(O, "+0x%" PRIx32, op->off);
284
5.38k
    break;
285
4.53k
  case BPF_OP_MEM:
286
4.53k
    SStream_concat(O, "[");
287
288
4.53k
    if (op->is_pkt && EBPF_MODE(MI->csh->mode)) {
289
1.49k
      SStream_concat(O, "skb");
290
291
1.49k
      if (op->mem.base != BPF_REG_INVALID)
292
496
        SStream_concat(O, "+%s",
293
496
                 BPF_reg_name((csh)MI->csh,
294
496
                  op->mem.base));
295
995
      else {
296
995
        if (op->is_signed)
297
995
          printInt32HexOffset(O, op->mem.disp);
298
0
        else
299
0
          SStream_concat(O, "+0x%" PRIx32,
300
0
                   op->mem.disp);
301
995
      }
302
3.04k
    } else {
303
3.04k
      if (op->mem.base != BPF_REG_INVALID)
304
2.59k
        SStream_concat(O, BPF_reg_name((csh)MI->csh,
305
2.59k
                     op->mem.base));
306
3.04k
      if (op->mem.disp != 0) {
307
2.96k
        if (op->mem.base != BPF_REG_INVALID) {
308
          // if operation is signed, then it always uses off, not k
309
2.54k
          if (op->is_signed)
310
2.04k
            printInt16HexOffset(
311
2.04k
              O, op->mem.disp);
312
501
          else if (op->is_pkt)
313
501
            SStream_concat(O, "+0x%" PRIx32,
314
501
                     op->mem.disp);
315
0
          else
316
0
            SStream_concat(O, "+0x%" PRIx16,
317
0
                     op->mem.disp);
318
2.54k
        } else
319
420
          SStream_concat(O, "0x%" PRIx32,
320
420
                   op->mem.disp);
321
2.96k
      }
322
323
3.04k
      if (op->mem.base == BPF_REG_INVALID &&
324
445
          op->mem.disp == 0)
325
25
        SStream_concat(O, "0x0");
326
3.04k
    }
327
328
4.53k
    SStream_concat(O, "]");
329
4.53k
    break;
330
261
  case BPF_OP_MMEM:
331
261
    SStream_concat(O, "m[0x%x]", op->mmem);
332
261
    break;
333
212
  case BPF_OP_MSH:
334
212
    SStream_concat(O, "4*([0x%x]&0xf)", op->msh);
335
212
    break;
336
68
  case BPF_OP_EXT:
337
68
    switch (op->ext) {
338
68
    case BPF_EXT_LEN:
339
68
      SStream_concat(O, "#len");
340
68
      break;
341
68
    }
342
68
    break;
343
29.2k
  }
344
29.2k
}
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
16.4k
{
353
16.4k
  cs_bpf bpf = { 0 };
354
355
  /* set pubOpcode as instruction id */
356
16.4k
  SStream_concat(O, BPF_insn_name((csh)MI->csh, MCInst_getOpcodePub(MI)));
357
16.4k
  convert_operands(MI, &bpf);
358
45.6k
  for (size_t i = 0; i < bpf.op_count; i++) {
359
29.2k
    if (i == 0)
360
15.8k
      SStream_concat(O, "\t");
361
13.3k
    else
362
13.3k
      SStream_concat(O, ", ");
363
29.2k
    print_operand(MI, O, &bpf.operands[i]);
364
29.2k
  }
365
366
16.4k
#ifndef CAPSTONE_DIET
367
16.4k
  if (detail_is_set(MI)) {
368
16.4k
    MI->flat_insn->detail->bpf = bpf;
369
16.4k
  }
370
16.4k
#endif
371
16.4k
}