1 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
2 * Copyright (c) 2016 Facebook
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of version 2 of the GNU General Public
6 * License as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 */
13
14 #include <linux/bpf.h>
15
16 #include "disasm.h"
17
18 #define __BPF_FUNC_STR_FN(x) [BPF_FUNC_ ## x] = __stringify(bpf_ ## x)
19 static const char * const func_id_str[] = {
20 __BPF_FUNC_MAPPER(__BPF_FUNC_STR_FN)
21 };
22 #undef __BPF_FUNC_STR_FN
23
__func_get_name(const struct bpf_insn_cbs * cbs,const struct bpf_insn * insn,char * buff,size_t len)24 static const char *__func_get_name(const struct bpf_insn_cbs *cbs,
25 const struct bpf_insn *insn,
26 char *buff, size_t len)
27 {
28 BUILD_BUG_ON(ARRAY_SIZE(func_id_str) != __BPF_FUNC_MAX_ID);
29
30 if (insn->src_reg != BPF_PSEUDO_CALL &&
31 insn->imm >= 0 && insn->imm < __BPF_FUNC_MAX_ID &&
32 func_id_str[insn->imm])
33 return func_id_str[insn->imm];
34
35 if (cbs && cbs->cb_call)
36 return cbs->cb_call(cbs->private_data, insn);
37
38 if (insn->src_reg == BPF_PSEUDO_CALL)
39 snprintf(buff, len, "%+d", insn->imm);
40
41 return buff;
42 }
43
__func_imm_name(const struct bpf_insn_cbs * cbs,const struct bpf_insn * insn,u64 full_imm,char * buff,size_t len)44 static const char *__func_imm_name(const struct bpf_insn_cbs *cbs,
45 const struct bpf_insn *insn,
46 u64 full_imm, char *buff, size_t len)
47 {
48 if (cbs && cbs->cb_imm)
49 return cbs->cb_imm(cbs->private_data, insn, full_imm);
50
51 snprintf(buff, len, "0x%llx", (unsigned long long)full_imm);
52 return buff;
53 }
54
func_id_name(int id)55 const char *func_id_name(int id)
56 {
57 if (id >= 0 && id < __BPF_FUNC_MAX_ID && func_id_str[id])
58 return func_id_str[id];
59 else
60 return "unknown";
61 }
62
63 const char *const bpf_class_string[8] = {
64 [BPF_LD] = "ld",
65 [BPF_LDX] = "ldx",
66 [BPF_ST] = "st",
67 [BPF_STX] = "stx",
68 [BPF_ALU] = "alu",
69 [BPF_JMP] = "jmp",
70 [BPF_JMP32] = "jmp32",
71 [BPF_ALU64] = "alu64",
72 };
73
74 const char *const bpf_alu_string[16] = {
75 [BPF_ADD >> 4] = "+=",
76 [BPF_SUB >> 4] = "-=",
77 [BPF_MUL >> 4] = "*=",
78 [BPF_DIV >> 4] = "/=",
79 [BPF_OR >> 4] = "|=",
80 [BPF_AND >> 4] = "&=",
81 [BPF_LSH >> 4] = "<<=",
82 [BPF_RSH >> 4] = ">>=",
83 [BPF_NEG >> 4] = "neg",
84 [BPF_MOD >> 4] = "%=",
85 [BPF_XOR >> 4] = "^=",
86 [BPF_MOV >> 4] = "=",
87 [BPF_ARSH >> 4] = "s>>=",
88 [BPF_END >> 4] = "endian",
89 };
90
91 static const char *const bpf_ldst_string[] = {
92 [BPF_W >> 3] = "u32",
93 [BPF_H >> 3] = "u16",
94 [BPF_B >> 3] = "u8",
95 [BPF_DW >> 3] = "u64",
96 };
97
98 static const char *const bpf_jmp_string[16] = {
99 [BPF_JA >> 4] = "jmp",
100 [BPF_JEQ >> 4] = "==",
101 [BPF_JGT >> 4] = ">",
102 [BPF_JLT >> 4] = "<",
103 [BPF_JGE >> 4] = ">=",
104 [BPF_JLE >> 4] = "<=",
105 [BPF_JSET >> 4] = "&",
106 [BPF_JNE >> 4] = "!=",
107 [BPF_JSGT >> 4] = "s>",
108 [BPF_JSLT >> 4] = "s<",
109 [BPF_JSGE >> 4] = "s>=",
110 [BPF_JSLE >> 4] = "s<=",
111 [BPF_CALL >> 4] = "call",
112 [BPF_EXIT >> 4] = "exit",
113 };
114
print_bpf_end_insn(bpf_insn_print_t verbose,void * private_data,const struct bpf_insn * insn)115 static void print_bpf_end_insn(bpf_insn_print_t verbose,
116 void *private_data,
117 const struct bpf_insn *insn)
118 {
119 verbose(private_data, "(%02x) r%d = %s%d r%d\n",
120 insn->code, insn->dst_reg,
121 BPF_SRC(insn->code) == BPF_TO_BE ? "be" : "le",
122 insn->imm, insn->dst_reg);
123 }
124
print_bpf_insn(const struct bpf_insn_cbs * cbs,const struct bpf_insn * insn,bool allow_ptr_leaks)125 void print_bpf_insn(const struct bpf_insn_cbs *cbs,
126 const struct bpf_insn *insn,
127 bool allow_ptr_leaks)
128 {
129 const bpf_insn_print_t verbose = cbs->cb_print;
130 u8 class = BPF_CLASS(insn->code);
131
132 if (class == BPF_ALU || class == BPF_ALU64) {
133 if (BPF_OP(insn->code) == BPF_END) {
134 if (class == BPF_ALU64)
135 verbose(cbs->private_data, "BUG_alu64_%02x\n", insn->code);
136 else
137 print_bpf_end_insn(verbose, cbs->private_data, insn);
138 } else if (BPF_OP(insn->code) == BPF_NEG) {
139 verbose(cbs->private_data, "(%02x) %c%d = -%c%d\n",
140 insn->code, class == BPF_ALU ? 'w' : 'r',
141 insn->dst_reg, class == BPF_ALU ? 'w' : 'r',
142 insn->dst_reg);
143 } else if (BPF_SRC(insn->code) == BPF_X) {
144 verbose(cbs->private_data, "(%02x) %c%d %s %c%d\n",
145 insn->code, class == BPF_ALU ? 'w' : 'r',
146 insn->dst_reg,
147 bpf_alu_string[BPF_OP(insn->code) >> 4],
148 class == BPF_ALU ? 'w' : 'r',
149 insn->src_reg);
150 } else {
151 verbose(cbs->private_data, "(%02x) %c%d %s %d\n",
152 insn->code, class == BPF_ALU ? 'w' : 'r',
153 insn->dst_reg,
154 bpf_alu_string[BPF_OP(insn->code) >> 4],
155 insn->imm);
156 }
157 } else if (class == BPF_STX) {
158 if (BPF_MODE(insn->code) == BPF_MEM)
159 verbose(cbs->private_data, "(%02x) *(%s *)(r%d %+d) = r%d\n",
160 insn->code,
161 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
162 insn->dst_reg,
163 insn->off, insn->src_reg);
164 else if (BPF_MODE(insn->code) == BPF_XADD)
165 verbose(cbs->private_data, "(%02x) lock *(%s *)(r%d %+d) += r%d\n",
166 insn->code,
167 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
168 insn->dst_reg, insn->off,
169 insn->src_reg);
170 else
171 verbose(cbs->private_data, "BUG_%02x\n", insn->code);
172 } else if (class == BPF_ST) {
173 if (BPF_MODE(insn->code) == BPF_MEM) {
174 verbose(cbs->private_data, "(%02x) *(%s *)(r%d %+d) = %d\n",
175 insn->code,
176 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
177 insn->dst_reg,
178 insn->off, insn->imm);
179 } else if (BPF_MODE(insn->code) == 0xc0 /* BPF_NOSPEC, no UAPI */) {
180 verbose(cbs->private_data, "(%02x) nospec\n", insn->code);
181 } else {
182 verbose(cbs->private_data, "BUG_st_%02x\n", insn->code);
183 }
184 } else if (class == BPF_LDX) {
185 if (BPF_MODE(insn->code) != BPF_MEM) {
186 verbose(cbs->private_data, "BUG_ldx_%02x\n", insn->code);
187 return;
188 }
189 verbose(cbs->private_data, "(%02x) r%d = *(%s *)(r%d %+d)\n",
190 insn->code, insn->dst_reg,
191 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
192 insn->src_reg, insn->off);
193 } else if (class == BPF_LD) {
194 if (BPF_MODE(insn->code) == BPF_ABS) {
195 verbose(cbs->private_data, "(%02x) r0 = *(%s *)skb[%d]\n",
196 insn->code,
197 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
198 insn->imm);
199 } else if (BPF_MODE(insn->code) == BPF_IND) {
200 verbose(cbs->private_data, "(%02x) r0 = *(%s *)skb[r%d + %d]\n",
201 insn->code,
202 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
203 insn->src_reg, insn->imm);
204 } else if (BPF_MODE(insn->code) == BPF_IMM &&
205 BPF_SIZE(insn->code) == BPF_DW) {
206 /* At this point, we already made sure that the second
207 * part of the ldimm64 insn is accessible.
208 */
209 u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
210 bool map_ptr = insn->src_reg == BPF_PSEUDO_MAP_FD;
211 char tmp[64];
212
213 if (map_ptr && !allow_ptr_leaks)
214 imm = 0;
215
216 verbose(cbs->private_data, "(%02x) r%d = %s\n",
217 insn->code, insn->dst_reg,
218 __func_imm_name(cbs, insn, imm,
219 tmp, sizeof(tmp)));
220 } else {
221 verbose(cbs->private_data, "BUG_ld_%02x\n", insn->code);
222 return;
223 }
224 } else if (class == BPF_JMP32 || class == BPF_JMP) {
225 u8 opcode = BPF_OP(insn->code);
226
227 if (opcode == BPF_CALL) {
228 char tmp[64];
229
230 if (insn->src_reg == BPF_PSEUDO_CALL) {
231 verbose(cbs->private_data, "(%02x) call pc%s\n",
232 insn->code,
233 __func_get_name(cbs, insn,
234 tmp, sizeof(tmp)));
235 } else {
236 strcpy(tmp, "unknown");
237 verbose(cbs->private_data, "(%02x) call %s#%d\n", insn->code,
238 __func_get_name(cbs, insn,
239 tmp, sizeof(tmp)),
240 insn->imm);
241 }
242 } else if (insn->code == (BPF_JMP | BPF_JA)) {
243 verbose(cbs->private_data, "(%02x) goto pc%+d\n",
244 insn->code, insn->off);
245 } else if (insn->code == (BPF_JMP | BPF_EXIT)) {
246 verbose(cbs->private_data, "(%02x) exit\n", insn->code);
247 } else if (BPF_SRC(insn->code) == BPF_X) {
248 verbose(cbs->private_data,
249 "(%02x) if %c%d %s %c%d goto pc%+d\n",
250 insn->code, class == BPF_JMP32 ? 'w' : 'r',
251 insn->dst_reg,
252 bpf_jmp_string[BPF_OP(insn->code) >> 4],
253 class == BPF_JMP32 ? 'w' : 'r',
254 insn->src_reg, insn->off);
255 } else {
256 verbose(cbs->private_data,
257 "(%02x) if %c%d %s 0x%x goto pc%+d\n",
258 insn->code, class == BPF_JMP32 ? 'w' : 'r',
259 insn->dst_reg,
260 bpf_jmp_string[BPF_OP(insn->code) >> 4],
261 insn->imm, insn->off);
262 }
263 } else {
264 verbose(cbs->private_data, "(%02x) %s\n",
265 insn->code, bpf_class_string[class]);
266 }
267 }
268