1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (c) 2019 Facebook 3 4 #include <fcntl.h> 5 #include <stdint.h> 6 #include <stdio.h> 7 #include <stdlib.h> 8 #include <string.h> 9 #include <unistd.h> 10 11 #include <linux/filter.h> 12 13 #include <bpf/bpf.h> 14 15 #include "bpf_rlimit.h" 16 #include "bpf_util.h" 17 #include "cgroup_helpers.h" 18 19 #define CG_PATH "/foo" 20 #define MAX_INSNS 512 21 #define FIXUP_SYSCTL_VALUE 0 22 23 char bpf_log_buf[BPF_LOG_BUF_SIZE]; 24 25 struct sysctl_test { 26 const char *descr; 27 size_t fixup_value_insn; 28 struct bpf_insn insns[MAX_INSNS]; 29 enum bpf_attach_type attach_type; 30 const char *sysctl; 31 int open_flags; 32 const char *newval; 33 const char *oldval; 34 enum { 35 LOAD_REJECT, 36 ATTACH_REJECT, 37 OP_EPERM, 38 SUCCESS, 39 } result; 40 }; 41 42 static struct sysctl_test tests[] = { 43 { 44 .descr = "sysctl wrong attach_type", 45 .insns = { 46 BPF_MOV64_IMM(BPF_REG_0, 1), 47 BPF_EXIT_INSN(), 48 }, 49 .attach_type = 0, 50 .sysctl = "kernel/ostype", 51 .open_flags = O_RDONLY, 52 .result = ATTACH_REJECT, 53 }, 54 { 55 .descr = "sysctl:read allow all", 56 .insns = { 57 BPF_MOV64_IMM(BPF_REG_0, 1), 58 BPF_EXIT_INSN(), 59 }, 60 .attach_type = BPF_CGROUP_SYSCTL, 61 .sysctl = "kernel/ostype", 62 .open_flags = O_RDONLY, 63 .result = SUCCESS, 64 }, 65 { 66 .descr = "sysctl:read deny all", 67 .insns = { 68 BPF_MOV64_IMM(BPF_REG_0, 0), 69 BPF_EXIT_INSN(), 70 }, 71 .attach_type = BPF_CGROUP_SYSCTL, 72 .sysctl = "kernel/ostype", 73 .open_flags = O_RDONLY, 74 .result = OP_EPERM, 75 }, 76 { 77 .descr = "ctx:write sysctl:read read ok", 78 .insns = { 79 /* If (write) */ 80 BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_1, 81 offsetof(struct bpf_sysctl, write)), 82 BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 1, 2), 83 84 /* return DENY; */ 85 BPF_MOV64_IMM(BPF_REG_0, 0), 86 BPF_JMP_A(1), 87 88 /* else return ALLOW; */ 89 BPF_MOV64_IMM(BPF_REG_0, 1), 90 BPF_EXIT_INSN(), 91 }, 92 .attach_type = BPF_CGROUP_SYSCTL, 93 .sysctl = "kernel/ostype", 94 .open_flags = O_RDONLY, 95 .result = SUCCESS, 96 }, 97 { 98 .descr = "ctx:write sysctl:write read ok", 99 .insns = { 100 /* If (write) */ 101 BPF_LDX_MEM(BPF_B, BPF_REG_7, BPF_REG_1, 102 offsetof(struct bpf_sysctl, write)), 103 BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 1, 2), 104 105 /* return DENY; */ 106 BPF_MOV64_IMM(BPF_REG_0, 0), 107 BPF_JMP_A(1), 108 109 /* else return ALLOW; */ 110 BPF_MOV64_IMM(BPF_REG_0, 1), 111 BPF_EXIT_INSN(), 112 }, 113 .attach_type = BPF_CGROUP_SYSCTL, 114 .sysctl = "kernel/domainname", 115 .open_flags = O_WRONLY, 116 .newval = "(none)", /* same as default, should fail anyway */ 117 .result = OP_EPERM, 118 }, 119 { 120 .descr = "ctx:write sysctl:read write reject", 121 .insns = { 122 /* write = X */ 123 BPF_MOV64_IMM(BPF_REG_0, 0), 124 BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0, 125 offsetof(struct bpf_sysctl, write)), 126 BPF_MOV64_IMM(BPF_REG_0, 1), 127 BPF_EXIT_INSN(), 128 }, 129 .attach_type = BPF_CGROUP_SYSCTL, 130 .sysctl = "kernel/ostype", 131 .open_flags = O_RDONLY, 132 .result = LOAD_REJECT, 133 }, 134 { 135 .descr = "ctx:file_pos sysctl:read read ok", 136 .insns = { 137 /* If (file_pos == X) */ 138 BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_1, 139 offsetof(struct bpf_sysctl, file_pos)), 140 BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 0, 2), 141 142 /* return ALLOW; */ 143 BPF_MOV64_IMM(BPF_REG_0, 1), 144 BPF_JMP_A(1), 145 146 /* else return DENY; */ 147 BPF_MOV64_IMM(BPF_REG_0, 0), 148 BPF_EXIT_INSN(), 149 }, 150 .attach_type = BPF_CGROUP_SYSCTL, 151 .sysctl = "kernel/ostype", 152 .open_flags = O_RDONLY, 153 .result = SUCCESS, 154 }, 155 { 156 .descr = "ctx:file_pos sysctl:read read ok narrow", 157 .insns = { 158 /* If (file_pos == X) */ 159 BPF_LDX_MEM(BPF_B, BPF_REG_7, BPF_REG_1, 160 offsetof(struct bpf_sysctl, file_pos)), 161 BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 0, 2), 162 163 /* return ALLOW; */ 164 BPF_MOV64_IMM(BPF_REG_0, 1), 165 BPF_JMP_A(1), 166 167 /* else return DENY; */ 168 BPF_MOV64_IMM(BPF_REG_0, 0), 169 BPF_EXIT_INSN(), 170 }, 171 .attach_type = BPF_CGROUP_SYSCTL, 172 .sysctl = "kernel/ostype", 173 .open_flags = O_RDONLY, 174 .result = SUCCESS, 175 }, 176 { 177 .descr = "ctx:file_pos sysctl:read write ok", 178 .insns = { 179 /* file_pos = X */ 180 BPF_MOV64_IMM(BPF_REG_0, 2), 181 BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0, 182 offsetof(struct bpf_sysctl, file_pos)), 183 BPF_MOV64_IMM(BPF_REG_0, 1), 184 BPF_EXIT_INSN(), 185 }, 186 .attach_type = BPF_CGROUP_SYSCTL, 187 .sysctl = "kernel/ostype", 188 .open_flags = O_RDONLY, 189 .oldval = "nux\n", 190 .result = SUCCESS, 191 }, 192 { 193 .descr = "sysctl_get_name sysctl_value:base ok", 194 .insns = { 195 /* sysctl_get_name arg2 (buf) */ 196 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 197 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 198 BPF_MOV64_IMM(BPF_REG_0, 0), 199 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0), 200 201 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 202 203 /* sysctl_get_name arg3 (buf_len) */ 204 BPF_MOV64_IMM(BPF_REG_3, 8), 205 206 /* sysctl_get_name arg4 (flags) */ 207 BPF_MOV64_IMM(BPF_REG_4, BPF_F_SYSCTL_BASE_NAME), 208 209 /* sysctl_get_name(ctx, buf, buf_len, flags) */ 210 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name), 211 212 /* if (ret == expected && */ 213 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, sizeof("tcp_mem") - 1, 6), 214 /* buf == "tcp_mem\0") */ 215 BPF_LD_IMM64(BPF_REG_8, 0x006d656d5f706374ULL), 216 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 217 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 218 219 /* return ALLOW; */ 220 BPF_MOV64_IMM(BPF_REG_0, 1), 221 BPF_JMP_A(1), 222 223 /* else return DENY; */ 224 BPF_MOV64_IMM(BPF_REG_0, 0), 225 BPF_EXIT_INSN(), 226 }, 227 .attach_type = BPF_CGROUP_SYSCTL, 228 .sysctl = "net/ipv4/tcp_mem", 229 .open_flags = O_RDONLY, 230 .result = SUCCESS, 231 }, 232 { 233 .descr = "sysctl_get_name sysctl_value:base E2BIG truncated", 234 .insns = { 235 /* sysctl_get_name arg2 (buf) */ 236 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 237 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 238 BPF_MOV64_IMM(BPF_REG_0, 0), 239 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0), 240 241 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 242 243 /* sysctl_get_name arg3 (buf_len) too small */ 244 BPF_MOV64_IMM(BPF_REG_3, 7), 245 246 /* sysctl_get_name arg4 (flags) */ 247 BPF_MOV64_IMM(BPF_REG_4, BPF_F_SYSCTL_BASE_NAME), 248 249 /* sysctl_get_name(ctx, buf, buf_len, flags) */ 250 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name), 251 252 /* if (ret == expected && */ 253 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 6), 254 255 /* buf[0:7] == "tcp_me\0") */ 256 BPF_LD_IMM64(BPF_REG_8, 0x00656d5f706374ULL), 257 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 258 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 259 260 /* return ALLOW; */ 261 BPF_MOV64_IMM(BPF_REG_0, 1), 262 BPF_JMP_A(1), 263 264 /* else return DENY; */ 265 BPF_MOV64_IMM(BPF_REG_0, 0), 266 BPF_EXIT_INSN(), 267 }, 268 .attach_type = BPF_CGROUP_SYSCTL, 269 .sysctl = "net/ipv4/tcp_mem", 270 .open_flags = O_RDONLY, 271 .result = SUCCESS, 272 }, 273 { 274 .descr = "sysctl_get_name sysctl:full ok", 275 .insns = { 276 /* sysctl_get_name arg2 (buf) */ 277 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 278 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -24), 279 BPF_MOV64_IMM(BPF_REG_0, 0), 280 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0), 281 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 8), 282 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 16), 283 284 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 285 286 /* sysctl_get_name arg3 (buf_len) */ 287 BPF_MOV64_IMM(BPF_REG_3, 17), 288 289 /* sysctl_get_name arg4 (flags) */ 290 BPF_MOV64_IMM(BPF_REG_4, 0), 291 292 /* sysctl_get_name(ctx, buf, buf_len, flags) */ 293 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name), 294 295 /* if (ret == expected && */ 296 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 16, 14), 297 298 /* buf[0:8] == "net/ipv4" && */ 299 BPF_LD_IMM64(BPF_REG_8, 0x347670692f74656eULL), 300 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 301 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 10), 302 303 /* buf[8:16] == "/tcp_mem" && */ 304 BPF_LD_IMM64(BPF_REG_8, 0x6d656d5f7063742fULL), 305 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 8), 306 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 6), 307 308 /* buf[16:24] == "\0") */ 309 BPF_LD_IMM64(BPF_REG_8, 0x0ULL), 310 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 16), 311 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 312 313 /* return ALLOW; */ 314 BPF_MOV64_IMM(BPF_REG_0, 1), 315 BPF_JMP_A(1), 316 317 /* else return DENY; */ 318 BPF_MOV64_IMM(BPF_REG_0, 0), 319 BPF_EXIT_INSN(), 320 }, 321 .attach_type = BPF_CGROUP_SYSCTL, 322 .sysctl = "net/ipv4/tcp_mem", 323 .open_flags = O_RDONLY, 324 .result = SUCCESS, 325 }, 326 { 327 .descr = "sysctl_get_name sysctl:full E2BIG truncated", 328 .insns = { 329 /* sysctl_get_name arg2 (buf) */ 330 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 331 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -16), 332 BPF_MOV64_IMM(BPF_REG_0, 0), 333 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0), 334 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 8), 335 336 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 337 338 /* sysctl_get_name arg3 (buf_len) */ 339 BPF_MOV64_IMM(BPF_REG_3, 16), 340 341 /* sysctl_get_name arg4 (flags) */ 342 BPF_MOV64_IMM(BPF_REG_4, 0), 343 344 /* sysctl_get_name(ctx, buf, buf_len, flags) */ 345 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name), 346 347 /* if (ret == expected && */ 348 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 10), 349 350 /* buf[0:8] == "net/ipv4" && */ 351 BPF_LD_IMM64(BPF_REG_8, 0x347670692f74656eULL), 352 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 353 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 6), 354 355 /* buf[8:16] == "/tcp_me\0") */ 356 BPF_LD_IMM64(BPF_REG_8, 0x00656d5f7063742fULL), 357 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 8), 358 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 359 360 /* return ALLOW; */ 361 BPF_MOV64_IMM(BPF_REG_0, 1), 362 BPF_JMP_A(1), 363 364 /* else return DENY; */ 365 BPF_MOV64_IMM(BPF_REG_0, 0), 366 BPF_EXIT_INSN(), 367 }, 368 .attach_type = BPF_CGROUP_SYSCTL, 369 .sysctl = "net/ipv4/tcp_mem", 370 .open_flags = O_RDONLY, 371 .result = SUCCESS, 372 }, 373 { 374 .descr = "sysctl_get_name sysctl:full E2BIG truncated small", 375 .insns = { 376 /* sysctl_get_name arg2 (buf) */ 377 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 378 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 379 BPF_MOV64_IMM(BPF_REG_0, 0), 380 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0), 381 382 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 383 384 /* sysctl_get_name arg3 (buf_len) */ 385 BPF_MOV64_IMM(BPF_REG_3, 7), 386 387 /* sysctl_get_name arg4 (flags) */ 388 BPF_MOV64_IMM(BPF_REG_4, 0), 389 390 /* sysctl_get_name(ctx, buf, buf_len, flags) */ 391 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name), 392 393 /* if (ret == expected && */ 394 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 6), 395 396 /* buf[0:8] == "net/ip\0") */ 397 BPF_LD_IMM64(BPF_REG_8, 0x000070692f74656eULL), 398 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 399 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 400 401 /* return ALLOW; */ 402 BPF_MOV64_IMM(BPF_REG_0, 1), 403 BPF_JMP_A(1), 404 405 /* else return DENY; */ 406 BPF_MOV64_IMM(BPF_REG_0, 0), 407 BPF_EXIT_INSN(), 408 }, 409 .attach_type = BPF_CGROUP_SYSCTL, 410 .sysctl = "net/ipv4/tcp_mem", 411 .open_flags = O_RDONLY, 412 .result = SUCCESS, 413 }, 414 { 415 .descr = "sysctl_get_current_value sysctl:read ok, gt", 416 .insns = { 417 /* sysctl_get_current_value arg2 (buf) */ 418 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 419 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 420 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 421 422 /* sysctl_get_current_value arg3 (buf_len) */ 423 BPF_MOV64_IMM(BPF_REG_3, 8), 424 425 /* sysctl_get_current_value(ctx, buf, buf_len) */ 426 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value), 427 428 /* if (ret == expected && */ 429 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 6, 6), 430 431 /* buf[0:6] == "Linux\n\0") */ 432 BPF_LD_IMM64(BPF_REG_8, 0x000a78756e694cULL), 433 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 434 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 435 436 /* return ALLOW; */ 437 BPF_MOV64_IMM(BPF_REG_0, 1), 438 BPF_JMP_A(1), 439 440 /* else return DENY; */ 441 BPF_MOV64_IMM(BPF_REG_0, 0), 442 BPF_EXIT_INSN(), 443 }, 444 .attach_type = BPF_CGROUP_SYSCTL, 445 .sysctl = "kernel/ostype", 446 .open_flags = O_RDONLY, 447 .result = SUCCESS, 448 }, 449 { 450 .descr = "sysctl_get_current_value sysctl:read ok, eq", 451 .insns = { 452 /* sysctl_get_current_value arg2 (buf) */ 453 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 454 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 455 BPF_MOV64_IMM(BPF_REG_0, 0), 456 BPF_STX_MEM(BPF_B, BPF_REG_7, BPF_REG_0, 7), 457 458 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 459 460 /* sysctl_get_current_value arg3 (buf_len) */ 461 BPF_MOV64_IMM(BPF_REG_3, 7), 462 463 /* sysctl_get_current_value(ctx, buf, buf_len) */ 464 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value), 465 466 /* if (ret == expected && */ 467 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 6, 6), 468 469 /* buf[0:6] == "Linux\n\0") */ 470 BPF_LD_IMM64(BPF_REG_8, 0x000a78756e694cULL), 471 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 472 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 473 474 /* return ALLOW; */ 475 BPF_MOV64_IMM(BPF_REG_0, 1), 476 BPF_JMP_A(1), 477 478 /* else return DENY; */ 479 BPF_MOV64_IMM(BPF_REG_0, 0), 480 BPF_EXIT_INSN(), 481 }, 482 .attach_type = BPF_CGROUP_SYSCTL, 483 .sysctl = "kernel/ostype", 484 .open_flags = O_RDONLY, 485 .result = SUCCESS, 486 }, 487 { 488 .descr = "sysctl_get_current_value sysctl:read E2BIG truncated", 489 .insns = { 490 /* sysctl_get_current_value arg2 (buf) */ 491 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 492 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 493 BPF_MOV64_IMM(BPF_REG_0, 0), 494 BPF_STX_MEM(BPF_H, BPF_REG_7, BPF_REG_0, 6), 495 496 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 497 498 /* sysctl_get_current_value arg3 (buf_len) */ 499 BPF_MOV64_IMM(BPF_REG_3, 6), 500 501 /* sysctl_get_current_value(ctx, buf, buf_len) */ 502 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value), 503 504 /* if (ret == expected && */ 505 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 6), 506 507 /* buf[0:6] == "Linux\0") */ 508 BPF_LD_IMM64(BPF_REG_8, 0x000078756e694cULL), 509 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 510 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 511 512 /* return ALLOW; */ 513 BPF_MOV64_IMM(BPF_REG_0, 1), 514 BPF_JMP_A(1), 515 516 /* else return DENY; */ 517 BPF_MOV64_IMM(BPF_REG_0, 0), 518 BPF_EXIT_INSN(), 519 }, 520 .attach_type = BPF_CGROUP_SYSCTL, 521 .sysctl = "kernel/ostype", 522 .open_flags = O_RDONLY, 523 .result = SUCCESS, 524 }, 525 { 526 .descr = "sysctl_get_current_value sysctl:read EINVAL", 527 .insns = { 528 /* sysctl_get_current_value arg2 (buf) */ 529 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 530 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 531 532 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 533 534 /* sysctl_get_current_value arg3 (buf_len) */ 535 BPF_MOV64_IMM(BPF_REG_3, 8), 536 537 /* sysctl_get_current_value(ctx, buf, buf_len) */ 538 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value), 539 540 /* if (ret == expected && */ 541 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -EINVAL, 4), 542 543 /* buf[0:8] is NUL-filled) */ 544 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 545 BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 0, 2), 546 547 /* return DENY; */ 548 BPF_MOV64_IMM(BPF_REG_0, 0), 549 BPF_JMP_A(1), 550 551 /* else return ALLOW; */ 552 BPF_MOV64_IMM(BPF_REG_0, 1), 553 BPF_EXIT_INSN(), 554 }, 555 .attach_type = BPF_CGROUP_SYSCTL, 556 .sysctl = "net/ipv6/conf/lo/stable_secret", /* -EIO */ 557 .open_flags = O_RDONLY, 558 .result = OP_EPERM, 559 }, 560 { 561 .descr = "sysctl_get_current_value sysctl:write ok", 562 .fixup_value_insn = 6, 563 .insns = { 564 /* sysctl_get_current_value arg2 (buf) */ 565 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 566 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 567 568 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 569 570 /* sysctl_get_current_value arg3 (buf_len) */ 571 BPF_MOV64_IMM(BPF_REG_3, 8), 572 573 /* sysctl_get_current_value(ctx, buf, buf_len) */ 574 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value), 575 576 /* if (ret == expected && */ 577 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 4, 6), 578 579 /* buf[0:4] == expected) */ 580 BPF_LD_IMM64(BPF_REG_8, FIXUP_SYSCTL_VALUE), 581 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 582 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 583 584 /* return DENY; */ 585 BPF_MOV64_IMM(BPF_REG_0, 0), 586 BPF_JMP_A(1), 587 588 /* else return ALLOW; */ 589 BPF_MOV64_IMM(BPF_REG_0, 1), 590 BPF_EXIT_INSN(), 591 }, 592 .attach_type = BPF_CGROUP_SYSCTL, 593 .sysctl = "net/ipv4/route/mtu_expires", 594 .open_flags = O_WRONLY, 595 .newval = "600", /* same as default, should fail anyway */ 596 .result = OP_EPERM, 597 }, 598 { 599 .descr = "sysctl_get_new_value sysctl:read EINVAL", 600 .insns = { 601 /* sysctl_get_new_value arg2 (buf) */ 602 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 603 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 604 BPF_MOV64_IMM(BPF_REG_0, 0), 605 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0), 606 607 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 608 609 /* sysctl_get_new_value arg3 (buf_len) */ 610 BPF_MOV64_IMM(BPF_REG_3, 8), 611 612 /* sysctl_get_new_value(ctx, buf, buf_len) */ 613 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_new_value), 614 615 /* if (ret == expected) */ 616 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -EINVAL, 2), 617 618 /* return ALLOW; */ 619 BPF_MOV64_IMM(BPF_REG_0, 1), 620 BPF_JMP_A(1), 621 622 /* else return DENY; */ 623 BPF_MOV64_IMM(BPF_REG_0, 0), 624 BPF_EXIT_INSN(), 625 }, 626 .attach_type = BPF_CGROUP_SYSCTL, 627 .sysctl = "net/ipv4/tcp_mem", 628 .open_flags = O_RDONLY, 629 .result = SUCCESS, 630 }, 631 { 632 .descr = "sysctl_get_new_value sysctl:write ok", 633 .insns = { 634 /* sysctl_get_new_value arg2 (buf) */ 635 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 636 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 637 638 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 639 640 /* sysctl_get_new_value arg3 (buf_len) */ 641 BPF_MOV64_IMM(BPF_REG_3, 4), 642 643 /* sysctl_get_new_value(ctx, buf, buf_len) */ 644 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_new_value), 645 646 /* if (ret == expected && */ 647 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 3, 4), 648 649 /* buf[0:4] == "606\0") */ 650 BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_7, 0), 651 BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 0x00363036, 2), 652 653 /* return DENY; */ 654 BPF_MOV64_IMM(BPF_REG_0, 0), 655 BPF_JMP_A(1), 656 657 /* else return ALLOW; */ 658 BPF_MOV64_IMM(BPF_REG_0, 1), 659 BPF_EXIT_INSN(), 660 }, 661 .attach_type = BPF_CGROUP_SYSCTL, 662 .sysctl = "net/ipv4/route/mtu_expires", 663 .open_flags = O_WRONLY, 664 .newval = "606", 665 .result = OP_EPERM, 666 }, 667 { 668 .descr = "sysctl_get_new_value sysctl:write ok long", 669 .insns = { 670 /* sysctl_get_new_value arg2 (buf) */ 671 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 672 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -24), 673 674 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 675 676 /* sysctl_get_new_value arg3 (buf_len) */ 677 BPF_MOV64_IMM(BPF_REG_3, 24), 678 679 /* sysctl_get_new_value(ctx, buf, buf_len) */ 680 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_new_value), 681 682 /* if (ret == expected && */ 683 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 23, 14), 684 685 /* buf[0:8] == "3000000 " && */ 686 BPF_LD_IMM64(BPF_REG_8, 0x2030303030303033ULL), 687 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 688 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 10), 689 690 /* buf[8:16] == "4000000 " && */ 691 BPF_LD_IMM64(BPF_REG_8, 0x2030303030303034ULL), 692 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 8), 693 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 6), 694 695 /* buf[16:24] == "6000000\0") */ 696 BPF_LD_IMM64(BPF_REG_8, 0x0030303030303036ULL), 697 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 16), 698 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 699 700 /* return DENY; */ 701 BPF_MOV64_IMM(BPF_REG_0, 0), 702 BPF_JMP_A(1), 703 704 /* else return ALLOW; */ 705 BPF_MOV64_IMM(BPF_REG_0, 1), 706 BPF_EXIT_INSN(), 707 }, 708 .attach_type = BPF_CGROUP_SYSCTL, 709 .sysctl = "net/ipv4/tcp_mem", 710 .open_flags = O_WRONLY, 711 .newval = "3000000 4000000 6000000", 712 .result = OP_EPERM, 713 }, 714 { 715 .descr = "sysctl_get_new_value sysctl:write E2BIG", 716 .insns = { 717 /* sysctl_get_new_value arg2 (buf) */ 718 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 719 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 720 BPF_MOV64_IMM(BPF_REG_0, 0), 721 BPF_STX_MEM(BPF_B, BPF_REG_7, BPF_REG_0, 3), 722 723 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 724 725 /* sysctl_get_new_value arg3 (buf_len) */ 726 BPF_MOV64_IMM(BPF_REG_3, 3), 727 728 /* sysctl_get_new_value(ctx, buf, buf_len) */ 729 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_new_value), 730 731 /* if (ret == expected && */ 732 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 4), 733 734 /* buf[0:3] == "60\0") */ 735 BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_7, 0), 736 BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 0x003036, 2), 737 738 /* return DENY; */ 739 BPF_MOV64_IMM(BPF_REG_0, 0), 740 BPF_JMP_A(1), 741 742 /* else return ALLOW; */ 743 BPF_MOV64_IMM(BPF_REG_0, 1), 744 BPF_EXIT_INSN(), 745 }, 746 .attach_type = BPF_CGROUP_SYSCTL, 747 .sysctl = "net/ipv4/route/mtu_expires", 748 .open_flags = O_WRONLY, 749 .newval = "606", 750 .result = OP_EPERM, 751 }, 752 { 753 .descr = "sysctl_set_new_value sysctl:read EINVAL", 754 .insns = { 755 /* sysctl_set_new_value arg2 (buf) */ 756 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 757 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 758 BPF_MOV64_IMM(BPF_REG_0, 0x00303036), 759 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0), 760 761 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 762 763 /* sysctl_set_new_value arg3 (buf_len) */ 764 BPF_MOV64_IMM(BPF_REG_3, 3), 765 766 /* sysctl_set_new_value(ctx, buf, buf_len) */ 767 BPF_EMIT_CALL(BPF_FUNC_sysctl_set_new_value), 768 769 /* if (ret == expected) */ 770 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -EINVAL, 2), 771 772 /* return ALLOW; */ 773 BPF_MOV64_IMM(BPF_REG_0, 1), 774 BPF_JMP_A(1), 775 776 /* else return DENY; */ 777 BPF_MOV64_IMM(BPF_REG_0, 0), 778 BPF_EXIT_INSN(), 779 }, 780 .attach_type = BPF_CGROUP_SYSCTL, 781 .sysctl = "net/ipv4/route/mtu_expires", 782 .open_flags = O_RDONLY, 783 .result = SUCCESS, 784 }, 785 { 786 .descr = "sysctl_set_new_value sysctl:write ok", 787 .fixup_value_insn = 2, 788 .insns = { 789 /* sysctl_set_new_value arg2 (buf) */ 790 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 791 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 792 BPF_MOV64_IMM(BPF_REG_0, FIXUP_SYSCTL_VALUE), 793 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0), 794 795 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 796 797 /* sysctl_set_new_value arg3 (buf_len) */ 798 BPF_MOV64_IMM(BPF_REG_3, 3), 799 800 /* sysctl_set_new_value(ctx, buf, buf_len) */ 801 BPF_EMIT_CALL(BPF_FUNC_sysctl_set_new_value), 802 803 /* if (ret == expected) */ 804 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 2), 805 806 /* return ALLOW; */ 807 BPF_MOV64_IMM(BPF_REG_0, 1), 808 BPF_JMP_A(1), 809 810 /* else return DENY; */ 811 BPF_MOV64_IMM(BPF_REG_0, 0), 812 BPF_EXIT_INSN(), 813 }, 814 .attach_type = BPF_CGROUP_SYSCTL, 815 .sysctl = "net/ipv4/route/mtu_expires", 816 .open_flags = O_WRONLY, 817 .newval = "606", 818 .result = SUCCESS, 819 }, 820 }; 821 822 static size_t probe_prog_length(const struct bpf_insn *fp) 823 { 824 size_t len; 825 826 for (len = MAX_INSNS - 1; len > 0; --len) 827 if (fp[len].code != 0 || fp[len].imm != 0) 828 break; 829 return len + 1; 830 } 831 832 static int fixup_sysctl_value(const char *buf, size_t buf_len, 833 struct bpf_insn *prog, size_t insn_num) 834 { 835 uint32_t value_num = 0; 836 uint8_t c, i; 837 838 if (buf_len > sizeof(value_num)) { 839 log_err("Value is too big (%zd) to use in fixup", buf_len); 840 return -1; 841 } 842 843 for (i = 0; i < buf_len; ++i) { 844 c = buf[i]; 845 value_num |= (c << i * 8); 846 } 847 848 prog[insn_num].imm = value_num; 849 850 return 0; 851 } 852 853 static int load_sysctl_prog(struct sysctl_test *test, const char *sysctl_path) 854 { 855 struct bpf_insn *prog = test->insns; 856 struct bpf_load_program_attr attr; 857 int ret; 858 859 memset(&attr, 0, sizeof(struct bpf_load_program_attr)); 860 attr.prog_type = BPF_PROG_TYPE_CGROUP_SYSCTL; 861 attr.insns = prog; 862 attr.insns_cnt = probe_prog_length(attr.insns); 863 attr.license = "GPL"; 864 865 if (test->fixup_value_insn) { 866 char buf[128]; 867 ssize_t len; 868 int fd; 869 870 fd = open(sysctl_path, O_RDONLY | O_CLOEXEC); 871 if (fd < 0) { 872 log_err("open(%s) failed", sysctl_path); 873 return -1; 874 } 875 len = read(fd, buf, sizeof(buf)); 876 if (len == -1) { 877 log_err("read(%s) failed", sysctl_path); 878 close(fd); 879 return -1; 880 } 881 close(fd); 882 if (fixup_sysctl_value(buf, len, prog, test->fixup_value_insn)) 883 return -1; 884 } 885 886 ret = bpf_load_program_xattr(&attr, bpf_log_buf, BPF_LOG_BUF_SIZE); 887 if (ret < 0 && test->result != LOAD_REJECT) { 888 log_err(">>> Loading program error.\n" 889 ">>> Verifier output:\n%s\n-------\n", bpf_log_buf); 890 } 891 892 return ret; 893 } 894 895 static int access_sysctl(const char *sysctl_path, 896 const struct sysctl_test *test) 897 { 898 int err = 0; 899 int fd; 900 901 fd = open(sysctl_path, test->open_flags | O_CLOEXEC); 902 if (fd < 0) 903 return fd; 904 905 if (test->open_flags == O_RDONLY) { 906 char buf[128]; 907 908 if (read(fd, buf, sizeof(buf)) == -1) 909 goto err; 910 if (test->oldval && 911 strncmp(buf, test->oldval, strlen(test->oldval))) { 912 log_err("Read value %s != %s", buf, test->oldval); 913 goto err; 914 } 915 } else if (test->open_flags == O_WRONLY) { 916 if (!test->newval) { 917 log_err("New value for sysctl is not set"); 918 goto err; 919 } 920 if (write(fd, test->newval, strlen(test->newval)) == -1) 921 goto err; 922 } else { 923 log_err("Unexpected sysctl access: neither read nor write"); 924 goto err; 925 } 926 927 goto out; 928 err: 929 err = -1; 930 out: 931 close(fd); 932 return err; 933 } 934 935 static int run_test_case(int cgfd, struct sysctl_test *test) 936 { 937 enum bpf_attach_type atype = test->attach_type; 938 char sysctl_path[128]; 939 int progfd = -1; 940 int err = 0; 941 942 printf("Test case: %s .. ", test->descr); 943 944 snprintf(sysctl_path, sizeof(sysctl_path), "/proc/sys/%s", 945 test->sysctl); 946 947 progfd = load_sysctl_prog(test, sysctl_path); 948 if (progfd < 0) { 949 if (test->result == LOAD_REJECT) 950 goto out; 951 else 952 goto err; 953 } 954 955 if (bpf_prog_attach(progfd, cgfd, atype, BPF_F_ALLOW_OVERRIDE) == -1) { 956 if (test->result == ATTACH_REJECT) 957 goto out; 958 else 959 goto err; 960 } 961 962 if (access_sysctl(sysctl_path, test) == -1) { 963 if (test->result == OP_EPERM && errno == EPERM) 964 goto out; 965 else 966 goto err; 967 } 968 969 if (test->result != SUCCESS) { 970 log_err("Unexpected failure"); 971 goto err; 972 } 973 974 goto out; 975 err: 976 err = -1; 977 out: 978 /* Detaching w/o checking return code: best effort attempt. */ 979 if (progfd != -1) 980 bpf_prog_detach(cgfd, atype); 981 close(progfd); 982 printf("[%s]\n", err ? "FAIL" : "PASS"); 983 return err; 984 } 985 986 static int run_tests(int cgfd) 987 { 988 int passes = 0; 989 int fails = 0; 990 int i; 991 992 for (i = 0; i < ARRAY_SIZE(tests); ++i) { 993 if (run_test_case(cgfd, &tests[i])) 994 ++fails; 995 else 996 ++passes; 997 } 998 printf("Summary: %d PASSED, %d FAILED\n", passes, fails); 999 return fails ? -1 : 0; 1000 } 1001 1002 int main(int argc, char **argv) 1003 { 1004 int cgfd = -1; 1005 int err = 0; 1006 1007 if (setup_cgroup_environment()) 1008 goto err; 1009 1010 cgfd = create_and_get_cgroup(CG_PATH); 1011 if (cgfd < 0) 1012 goto err; 1013 1014 if (join_cgroup(CG_PATH)) 1015 goto err; 1016 1017 if (run_tests(cgfd)) 1018 goto err; 1019 1020 goto out; 1021 err: 1022 err = -1; 1023 out: 1024 close(cgfd); 1025 cleanup_cgroup_environment(); 1026 return err; 1027 } 1028