Paul Jensen | d38fb766 | 2016-01-07 23:13:19 -0500 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2015 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
Paul Jensen | 9132f34 | 2016-04-13 15:00:26 -0400 | [diff] [blame] | 17 | package android.net.apf; |
Paul Jensen | d38fb766 | 2016-01-07 23:13:19 -0500 | [diff] [blame] | 18 | |
| 19 | import android.net.apf.ApfGenerator; |
| 20 | import android.net.apf.ApfGenerator.IllegalInstructionException; |
| 21 | import android.net.apf.ApfGenerator.Register; |
| 22 | |
| 23 | import java.io.BufferedReader; |
| 24 | import java.io.InputStreamReader; |
| 25 | |
| 26 | /** |
| 27 | * BPF to APF translator. |
| 28 | * |
| 29 | * Note: This is for testing purposes only and is not guaranteed to support |
| 30 | * translation of all BPF programs. |
| 31 | * |
| 32 | * Example usage: |
| 33 | * javac net/java/android/net/apf/ApfGenerator.java \ |
Paul Jensen | 9132f34 | 2016-04-13 15:00:26 -0400 | [diff] [blame] | 34 | * tests/servicestests/src/android/net/apf/Bpf2Apf.java |
Paul Jensen | d38fb766 | 2016-01-07 23:13:19 -0500 | [diff] [blame] | 35 | * sudo tcpdump -i em1 -d icmp | java -classpath tests/servicestests/src:net/java \ |
Paul Jensen | 9132f34 | 2016-04-13 15:00:26 -0400 | [diff] [blame] | 36 | * android.net.apf.Bpf2Apf |
Paul Jensen | d38fb766 | 2016-01-07 23:13:19 -0500 | [diff] [blame] | 37 | */ |
| 38 | public class Bpf2Apf { |
| 39 | private static int parseImm(String line, String arg) { |
| 40 | if (!arg.startsWith("#0x")) { |
| 41 | throw new IllegalArgumentException("Unhandled instruction: " + line); |
| 42 | } |
| 43 | final long val_long = Long.parseLong(arg.substring(3), 16); |
| 44 | if (val_long < 0 || val_long > Long.parseLong("ffffffff", 16)) { |
| 45 | throw new IllegalArgumentException("Unhandled instruction: " + line); |
| 46 | } |
| 47 | return new Long((val_long << 32) >> 32).intValue(); |
| 48 | } |
| 49 | |
| 50 | /** |
| 51 | * Convert a single line of "tcpdump -d" (human readable BPF program dump) {@code line} into |
| 52 | * APF instruction(s) and append them to {@code gen}. Here's an example line: |
| 53 | * (001) jeq #0x86dd jt 2 jf 7 |
| 54 | */ |
| 55 | private static void convertLine(String line, ApfGenerator gen) |
| 56 | throws IllegalInstructionException { |
| 57 | if (line.indexOf("(") != 0 || line.indexOf(")") != 4 || line.indexOf(" ") != 5) { |
| 58 | throw new IllegalArgumentException("Unhandled instruction: " + line); |
| 59 | } |
| 60 | int label = Integer.parseInt(line.substring(1, 4)); |
| 61 | gen.defineLabel(Integer.toString(label)); |
| 62 | String opcode = line.substring(6, 10).trim(); |
| 63 | String arg = line.substring(15, Math.min(32, line.length())).trim(); |
| 64 | switch (opcode) { |
| 65 | case "ld": |
| 66 | case "ldh": |
| 67 | case "ldb": |
| 68 | case "ldx": |
| 69 | case "ldxb": |
| 70 | case "ldxh": |
| 71 | Register dest = opcode.contains("x") ? Register.R1 : Register.R0; |
| 72 | if (arg.equals("4*([14]&0xf)")) { |
| 73 | if (!opcode.equals("ldxb")) { |
| 74 | throw new IllegalArgumentException("Unhandled instruction: " + line); |
| 75 | } |
| 76 | gen.addLoadFromMemory(dest, gen.IPV4_HEADER_SIZE_MEMORY_SLOT); |
| 77 | break; |
| 78 | } |
| 79 | if (arg.equals("#pktlen")) { |
| 80 | if (!opcode.equals("ld")) { |
| 81 | throw new IllegalArgumentException("Unhandled instruction: " + line); |
| 82 | } |
| 83 | gen.addLoadFromMemory(dest, gen.PACKET_SIZE_MEMORY_SLOT); |
| 84 | break; |
| 85 | } |
| 86 | if (arg.startsWith("#0x")) { |
| 87 | if (!opcode.equals("ld")) { |
| 88 | throw new IllegalArgumentException("Unhandled instruction: " + line); |
| 89 | } |
| 90 | gen.addLoadImmediate(dest, parseImm(line, arg)); |
| 91 | break; |
| 92 | } |
| 93 | if (arg.startsWith("M[")) { |
| 94 | if (!opcode.startsWith("ld")) { |
| 95 | throw new IllegalArgumentException("Unhandled instruction: " + line); |
| 96 | } |
| 97 | int memory_slot = Integer.parseInt(arg.substring(2, arg.length() - 1)); |
| 98 | if (memory_slot < 0 || memory_slot >= gen.MEMORY_SLOTS || |
| 99 | // Disallow use of pre-filled slots as BPF programs might |
| 100 | // wrongfully assume they're initialized to 0. |
| 101 | (memory_slot >= gen.FIRST_PREFILLED_MEMORY_SLOT && |
| 102 | memory_slot <= gen.LAST_PREFILLED_MEMORY_SLOT)) { |
| 103 | throw new IllegalArgumentException("Unhandled instruction: " + line); |
| 104 | } |
| 105 | gen.addLoadFromMemory(dest, memory_slot); |
| 106 | break; |
| 107 | } |
| 108 | if (arg.startsWith("[x + ")) { |
| 109 | int offset = Integer.parseInt(arg.substring(5, arg.length() - 1)); |
| 110 | switch (opcode) { |
| 111 | case "ld": |
| 112 | case "ldx": |
| 113 | gen.addLoad32Indexed(dest, offset); |
| 114 | break; |
| 115 | case "ldh": |
| 116 | case "ldxh": |
| 117 | gen.addLoad16Indexed(dest, offset); |
| 118 | break; |
| 119 | case "ldb": |
| 120 | case "ldxb": |
| 121 | gen.addLoad8Indexed(dest, offset); |
| 122 | break; |
| 123 | } |
| 124 | } else { |
| 125 | int offset = Integer.parseInt(arg.substring(1, arg.length() - 1)); |
| 126 | switch (opcode) { |
| 127 | case "ld": |
| 128 | case "ldx": |
| 129 | gen.addLoad32(dest, offset); |
| 130 | break; |
| 131 | case "ldh": |
| 132 | case "ldxh": |
| 133 | gen.addLoad16(dest, offset); |
| 134 | break; |
| 135 | case "ldb": |
| 136 | case "ldxb": |
| 137 | gen.addLoad8(dest, offset); |
| 138 | break; |
| 139 | } |
| 140 | } |
| 141 | break; |
| 142 | case "st": |
| 143 | case "stx": |
| 144 | Register src = opcode.contains("x") ? Register.R1 : Register.R0; |
| 145 | if (!arg.startsWith("M[")) { |
| 146 | throw new IllegalArgumentException("Unhandled instruction: " + line); |
| 147 | } |
| 148 | int memory_slot = Integer.parseInt(arg.substring(2, arg.length() - 1)); |
| 149 | if (memory_slot < 0 || memory_slot >= gen.MEMORY_SLOTS || |
| 150 | // Disallow overwriting pre-filled slots |
| 151 | (memory_slot >= gen.FIRST_PREFILLED_MEMORY_SLOT && |
| 152 | memory_slot <= gen.LAST_PREFILLED_MEMORY_SLOT)) { |
| 153 | throw new IllegalArgumentException("Unhandled instruction: " + line); |
| 154 | } |
| 155 | gen.addStoreToMemory(src, memory_slot); |
| 156 | break; |
| 157 | case "add": |
| 158 | case "and": |
| 159 | case "or": |
| 160 | case "sub": |
| 161 | if (arg.equals("x")) { |
| 162 | switch(opcode) { |
| 163 | case "add": |
| 164 | gen.addAddR1(); |
| 165 | break; |
| 166 | case "and": |
| 167 | gen.addAndR1(); |
| 168 | break; |
| 169 | case "or": |
| 170 | gen.addOrR1(); |
| 171 | break; |
| 172 | case "sub": |
| 173 | gen.addNeg(Register.R1); |
| 174 | gen.addAddR1(); |
| 175 | gen.addNeg(Register.R1); |
| 176 | break; |
| 177 | } |
| 178 | } else { |
| 179 | int imm = parseImm(line, arg); |
| 180 | switch(opcode) { |
| 181 | case "add": |
| 182 | gen.addAdd(imm); |
| 183 | break; |
| 184 | case "and": |
| 185 | gen.addAnd(imm); |
| 186 | break; |
| 187 | case "or": |
| 188 | gen.addOr(imm); |
| 189 | break; |
| 190 | case "sub": |
| 191 | gen.addAdd(-imm); |
| 192 | break; |
| 193 | } |
| 194 | } |
| 195 | break; |
| 196 | case "jeq": |
| 197 | case "jset": |
| 198 | case "jgt": |
| 199 | case "jge": |
| 200 | int val = 0; |
| 201 | boolean reg_compare; |
| 202 | if (arg.startsWith("x")) { |
| 203 | reg_compare = true; |
| 204 | } else { |
| 205 | reg_compare = false; |
| 206 | val = parseImm(line, arg); |
| 207 | } |
| 208 | int jt_offset = line.indexOf("jt"); |
| 209 | int jf_offset = line.indexOf("jf"); |
| 210 | String true_label = line.substring(jt_offset + 2, jf_offset).trim(); |
| 211 | String false_label = line.substring(jf_offset + 2).trim(); |
| 212 | boolean true_label_is_fallthrough = Integer.parseInt(true_label) == label + 1; |
| 213 | boolean false_label_is_fallthrough = Integer.parseInt(false_label) == label + 1; |
| 214 | if (true_label_is_fallthrough && false_label_is_fallthrough) |
| 215 | break; |
| 216 | switch (opcode) { |
| 217 | case "jeq": |
| 218 | if (!true_label_is_fallthrough) { |
| 219 | if (reg_compare) { |
| 220 | gen.addJumpIfR0EqualsR1(true_label); |
| 221 | } else { |
| 222 | gen.addJumpIfR0Equals(val, true_label); |
| 223 | } |
| 224 | } |
| 225 | if (!false_label_is_fallthrough) { |
| 226 | if (!true_label_is_fallthrough) { |
| 227 | gen.addJump(false_label); |
| 228 | } else if (reg_compare) { |
| 229 | gen.addJumpIfR0NotEqualsR1(false_label); |
| 230 | } else { |
| 231 | gen.addJumpIfR0NotEquals(val, false_label); |
| 232 | } |
| 233 | } |
| 234 | break; |
| 235 | case "jset": |
| 236 | if (reg_compare) { |
| 237 | gen.addJumpIfR0AnyBitsSetR1(true_label); |
| 238 | } else { |
| 239 | gen.addJumpIfR0AnyBitsSet(val, true_label); |
| 240 | } |
| 241 | if (!false_label_is_fallthrough) { |
| 242 | gen.addJump(false_label); |
| 243 | } |
| 244 | break; |
| 245 | case "jgt": |
| 246 | if (!true_label_is_fallthrough || |
| 247 | // We have no less-than-or-equal-to register to register |
| 248 | // comparison instruction, so in this case we'll jump |
| 249 | // around an unconditional jump. |
| 250 | (!false_label_is_fallthrough && reg_compare)) { |
| 251 | if (reg_compare) { |
| 252 | gen.addJumpIfR0GreaterThanR1(true_label); |
| 253 | } else { |
| 254 | gen.addJumpIfR0GreaterThan(val, true_label); |
| 255 | } |
| 256 | } |
| 257 | if (!false_label_is_fallthrough) { |
| 258 | if (!true_label_is_fallthrough || reg_compare) { |
| 259 | gen.addJump(false_label); |
| 260 | } else { |
| 261 | gen.addJumpIfR0LessThan(val + 1, false_label); |
| 262 | } |
| 263 | } |
| 264 | break; |
| 265 | case "jge": |
| 266 | if (!false_label_is_fallthrough || |
| 267 | // We have no greater-than-or-equal-to register to register |
| 268 | // comparison instruction, so in this case we'll jump |
| 269 | // around an unconditional jump. |
| 270 | (!true_label_is_fallthrough && reg_compare)) { |
| 271 | if (reg_compare) { |
| 272 | gen.addJumpIfR0LessThanR1(false_label); |
| 273 | } else { |
| 274 | gen.addJumpIfR0LessThan(val, false_label); |
| 275 | } |
| 276 | } |
| 277 | if (!true_label_is_fallthrough) { |
| 278 | if (!false_label_is_fallthrough || reg_compare) { |
| 279 | gen.addJump(true_label); |
| 280 | } else { |
| 281 | gen.addJumpIfR0GreaterThan(val - 1, true_label); |
| 282 | } |
| 283 | } |
| 284 | break; |
| 285 | } |
| 286 | break; |
| 287 | case "ret": |
| 288 | if (arg.equals("#0")) { |
| 289 | gen.addJump(gen.DROP_LABEL); |
| 290 | } else { |
| 291 | gen.addJump(gen.PASS_LABEL); |
| 292 | } |
| 293 | break; |
| 294 | case "tax": |
| 295 | gen.addMove(Register.R1); |
| 296 | break; |
| 297 | case "txa": |
| 298 | gen.addMove(Register.R0); |
| 299 | break; |
| 300 | default: |
| 301 | throw new IllegalArgumentException("Unhandled instruction: " + line); |
| 302 | } |
| 303 | } |
| 304 | |
| 305 | /** |
| 306 | * Convert the output of "tcpdump -d" (human readable BPF program dump) {@code bpf} into an APF |
| 307 | * program and return it. |
| 308 | */ |
| 309 | public static byte[] convert(String bpf) throws IllegalInstructionException { |
| 310 | ApfGenerator gen = new ApfGenerator(); |
| 311 | for (String line : bpf.split("\\n")) convertLine(line, gen); |
| 312 | return gen.generate(); |
| 313 | } |
| 314 | |
| 315 | /** |
| 316 | * Convert the output of "tcpdump -d" (human readable BPF program dump) piped in stdin into an |
| 317 | * APF program and output it via stdout. |
| 318 | */ |
| 319 | public static void main(String[] args) throws Exception { |
| 320 | BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); |
| 321 | String line = null; |
| 322 | StringBuilder responseData = new StringBuilder(); |
| 323 | ApfGenerator gen = new ApfGenerator(); |
| 324 | while ((line = in.readLine()) != null) convertLine(line, gen); |
| 325 | System.out.write(gen.generate()); |
| 326 | } |
| 327 | } |