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 enum { 34 LOAD_REJECT, 35 ATTACH_REJECT, 36 OP_EPERM, 37 SUCCESS, 38 } result; 39 }; 40 41 static struct sysctl_test tests[] = { 42 { 43 .descr = "sysctl wrong attach_type", 44 .insns = { 45 BPF_MOV64_IMM(BPF_REG_0, 1), 46 BPF_EXIT_INSN(), 47 }, 48 .attach_type = 0, 49 .sysctl = "kernel/ostype", 50 .open_flags = O_RDONLY, 51 .result = ATTACH_REJECT, 52 }, 53 { 54 .descr = "sysctl:read allow all", 55 .insns = { 56 BPF_MOV64_IMM(BPF_REG_0, 1), 57 BPF_EXIT_INSN(), 58 }, 59 .attach_type = BPF_CGROUP_SYSCTL, 60 .sysctl = "kernel/ostype", 61 .open_flags = O_RDONLY, 62 .result = SUCCESS, 63 }, 64 { 65 .descr = "sysctl:read deny all", 66 .insns = { 67 BPF_MOV64_IMM(BPF_REG_0, 0), 68 BPF_EXIT_INSN(), 69 }, 70 .attach_type = BPF_CGROUP_SYSCTL, 71 .sysctl = "kernel/ostype", 72 .open_flags = O_RDONLY, 73 .result = OP_EPERM, 74 }, 75 { 76 .descr = "ctx:write sysctl:read read ok", 77 .insns = { 78 /* If (write) */ 79 BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_1, 80 offsetof(struct bpf_sysctl, write)), 81 BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 1, 2), 82 83 /* return DENY; */ 84 BPF_MOV64_IMM(BPF_REG_0, 0), 85 BPF_JMP_A(1), 86 87 /* else return ALLOW; */ 88 BPF_MOV64_IMM(BPF_REG_0, 1), 89 BPF_EXIT_INSN(), 90 }, 91 .attach_type = BPF_CGROUP_SYSCTL, 92 .sysctl = "kernel/ostype", 93 .open_flags = O_RDONLY, 94 .result = SUCCESS, 95 }, 96 { 97 .descr = "ctx:write sysctl:write read ok", 98 .insns = { 99 /* If (write) */ 100 BPF_LDX_MEM(BPF_B, BPF_REG_7, BPF_REG_1, 101 offsetof(struct bpf_sysctl, write)), 102 BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 1, 2), 103 104 /* return DENY; */ 105 BPF_MOV64_IMM(BPF_REG_0, 0), 106 BPF_JMP_A(1), 107 108 /* else return ALLOW; */ 109 BPF_MOV64_IMM(BPF_REG_0, 1), 110 BPF_EXIT_INSN(), 111 }, 112 .attach_type = BPF_CGROUP_SYSCTL, 113 .sysctl = "kernel/domainname", 114 .open_flags = O_WRONLY, 115 .newval = "(none)", /* same as default, should fail anyway */ 116 .result = OP_EPERM, 117 }, 118 { 119 .descr = "ctx:write sysctl:read write reject", 120 .insns = { 121 /* write = X */ 122 BPF_MOV64_IMM(BPF_REG_0, 0), 123 BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0, 124 offsetof(struct bpf_sysctl, write)), 125 BPF_MOV64_IMM(BPF_REG_0, 1), 126 BPF_EXIT_INSN(), 127 }, 128 .attach_type = BPF_CGROUP_SYSCTL, 129 .sysctl = "kernel/ostype", 130 .open_flags = O_RDONLY, 131 .result = LOAD_REJECT, 132 }, 133 { 134 .descr = "sysctl_get_name sysctl_value:base ok", 135 .insns = { 136 /* sysctl_get_name arg2 (buf) */ 137 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 138 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 139 BPF_MOV64_IMM(BPF_REG_0, 0), 140 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0), 141 142 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 143 144 /* sysctl_get_name arg3 (buf_len) */ 145 BPF_MOV64_IMM(BPF_REG_3, 8), 146 147 /* sysctl_get_name arg4 (flags) */ 148 BPF_MOV64_IMM(BPF_REG_4, BPF_F_SYSCTL_BASE_NAME), 149 150 /* sysctl_get_name(ctx, buf, buf_len, flags) */ 151 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name), 152 153 /* if (ret == expected && */ 154 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, sizeof("tcp_mem") - 1, 6), 155 /* buf == "tcp_mem\0") */ 156 BPF_LD_IMM64(BPF_REG_8, 0x006d656d5f706374ULL), 157 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 158 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 159 160 /* return ALLOW; */ 161 BPF_MOV64_IMM(BPF_REG_0, 1), 162 BPF_JMP_A(1), 163 164 /* else return DENY; */ 165 BPF_MOV64_IMM(BPF_REG_0, 0), 166 BPF_EXIT_INSN(), 167 }, 168 .attach_type = BPF_CGROUP_SYSCTL, 169 .sysctl = "net/ipv4/tcp_mem", 170 .open_flags = O_RDONLY, 171 .result = SUCCESS, 172 }, 173 { 174 .descr = "sysctl_get_name sysctl_value:base E2BIG truncated", 175 .insns = { 176 /* sysctl_get_name arg2 (buf) */ 177 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 178 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 179 BPF_MOV64_IMM(BPF_REG_0, 0), 180 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0), 181 182 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 183 184 /* sysctl_get_name arg3 (buf_len) too small */ 185 BPF_MOV64_IMM(BPF_REG_3, 7), 186 187 /* sysctl_get_name arg4 (flags) */ 188 BPF_MOV64_IMM(BPF_REG_4, BPF_F_SYSCTL_BASE_NAME), 189 190 /* sysctl_get_name(ctx, buf, buf_len, flags) */ 191 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name), 192 193 /* if (ret == expected && */ 194 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 6), 195 196 /* buf[0:7] == "tcp_me\0") */ 197 BPF_LD_IMM64(BPF_REG_8, 0x00656d5f706374ULL), 198 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 199 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 200 201 /* return ALLOW; */ 202 BPF_MOV64_IMM(BPF_REG_0, 1), 203 BPF_JMP_A(1), 204 205 /* else return DENY; */ 206 BPF_MOV64_IMM(BPF_REG_0, 0), 207 BPF_EXIT_INSN(), 208 }, 209 .attach_type = BPF_CGROUP_SYSCTL, 210 .sysctl = "net/ipv4/tcp_mem", 211 .open_flags = O_RDONLY, 212 .result = SUCCESS, 213 }, 214 { 215 .descr = "sysctl_get_name sysctl:full ok", 216 .insns = { 217 /* sysctl_get_name arg2 (buf) */ 218 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 219 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -24), 220 BPF_MOV64_IMM(BPF_REG_0, 0), 221 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0), 222 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 8), 223 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 16), 224 225 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 226 227 /* sysctl_get_name arg3 (buf_len) */ 228 BPF_MOV64_IMM(BPF_REG_3, 17), 229 230 /* sysctl_get_name arg4 (flags) */ 231 BPF_MOV64_IMM(BPF_REG_4, 0), 232 233 /* sysctl_get_name(ctx, buf, buf_len, flags) */ 234 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name), 235 236 /* if (ret == expected && */ 237 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 16, 14), 238 239 /* buf[0:8] == "net/ipv4" && */ 240 BPF_LD_IMM64(BPF_REG_8, 0x347670692f74656eULL), 241 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 242 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 10), 243 244 /* buf[8:16] == "/tcp_mem" && */ 245 BPF_LD_IMM64(BPF_REG_8, 0x6d656d5f7063742fULL), 246 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 8), 247 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 6), 248 249 /* buf[16:24] == "\0") */ 250 BPF_LD_IMM64(BPF_REG_8, 0x0ULL), 251 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 16), 252 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 253 254 /* return ALLOW; */ 255 BPF_MOV64_IMM(BPF_REG_0, 1), 256 BPF_JMP_A(1), 257 258 /* else return DENY; */ 259 BPF_MOV64_IMM(BPF_REG_0, 0), 260 BPF_EXIT_INSN(), 261 }, 262 .attach_type = BPF_CGROUP_SYSCTL, 263 .sysctl = "net/ipv4/tcp_mem", 264 .open_flags = O_RDONLY, 265 .result = SUCCESS, 266 }, 267 { 268 .descr = "sysctl_get_name sysctl:full E2BIG truncated", 269 .insns = { 270 /* sysctl_get_name arg2 (buf) */ 271 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 272 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -16), 273 BPF_MOV64_IMM(BPF_REG_0, 0), 274 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0), 275 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 8), 276 277 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 278 279 /* sysctl_get_name arg3 (buf_len) */ 280 BPF_MOV64_IMM(BPF_REG_3, 16), 281 282 /* sysctl_get_name arg4 (flags) */ 283 BPF_MOV64_IMM(BPF_REG_4, 0), 284 285 /* sysctl_get_name(ctx, buf, buf_len, flags) */ 286 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name), 287 288 /* if (ret == expected && */ 289 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 10), 290 291 /* buf[0:8] == "net/ipv4" && */ 292 BPF_LD_IMM64(BPF_REG_8, 0x347670692f74656eULL), 293 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 294 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 6), 295 296 /* buf[8:16] == "/tcp_me\0") */ 297 BPF_LD_IMM64(BPF_REG_8, 0x00656d5f7063742fULL), 298 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 8), 299 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 300 301 /* return ALLOW; */ 302 BPF_MOV64_IMM(BPF_REG_0, 1), 303 BPF_JMP_A(1), 304 305 /* else return DENY; */ 306 BPF_MOV64_IMM(BPF_REG_0, 0), 307 BPF_EXIT_INSN(), 308 }, 309 .attach_type = BPF_CGROUP_SYSCTL, 310 .sysctl = "net/ipv4/tcp_mem", 311 .open_flags = O_RDONLY, 312 .result = SUCCESS, 313 }, 314 { 315 .descr = "sysctl_get_name sysctl:full E2BIG truncated small", 316 .insns = { 317 /* sysctl_get_name arg2 (buf) */ 318 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 319 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 320 BPF_MOV64_IMM(BPF_REG_0, 0), 321 BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0), 322 323 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 324 325 /* sysctl_get_name arg3 (buf_len) */ 326 BPF_MOV64_IMM(BPF_REG_3, 7), 327 328 /* sysctl_get_name arg4 (flags) */ 329 BPF_MOV64_IMM(BPF_REG_4, 0), 330 331 /* sysctl_get_name(ctx, buf, buf_len, flags) */ 332 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name), 333 334 /* if (ret == expected && */ 335 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 6), 336 337 /* buf[0:8] == "net/ip\0") */ 338 BPF_LD_IMM64(BPF_REG_8, 0x000070692f74656eULL), 339 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 340 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 341 342 /* return ALLOW; */ 343 BPF_MOV64_IMM(BPF_REG_0, 1), 344 BPF_JMP_A(1), 345 346 /* else return DENY; */ 347 BPF_MOV64_IMM(BPF_REG_0, 0), 348 BPF_EXIT_INSN(), 349 }, 350 .attach_type = BPF_CGROUP_SYSCTL, 351 .sysctl = "net/ipv4/tcp_mem", 352 .open_flags = O_RDONLY, 353 .result = SUCCESS, 354 }, 355 { 356 .descr = "sysctl_get_current_value sysctl:read ok, gt", 357 .insns = { 358 /* sysctl_get_current_value arg2 (buf) */ 359 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 360 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 361 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 362 363 /* sysctl_get_current_value arg3 (buf_len) */ 364 BPF_MOV64_IMM(BPF_REG_3, 8), 365 366 /* sysctl_get_current_value(ctx, buf, buf_len) */ 367 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value), 368 369 /* if (ret == expected && */ 370 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 6, 6), 371 372 /* buf[0:6] == "Linux\n\0") */ 373 BPF_LD_IMM64(BPF_REG_8, 0x000a78756e694cULL), 374 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 375 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 376 377 /* return ALLOW; */ 378 BPF_MOV64_IMM(BPF_REG_0, 1), 379 BPF_JMP_A(1), 380 381 /* else return DENY; */ 382 BPF_MOV64_IMM(BPF_REG_0, 0), 383 BPF_EXIT_INSN(), 384 }, 385 .attach_type = BPF_CGROUP_SYSCTL, 386 .sysctl = "kernel/ostype", 387 .open_flags = O_RDONLY, 388 .result = SUCCESS, 389 }, 390 { 391 .descr = "sysctl_get_current_value sysctl:read ok, eq", 392 .insns = { 393 /* sysctl_get_current_value arg2 (buf) */ 394 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 395 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 396 BPF_MOV64_IMM(BPF_REG_0, 0), 397 BPF_STX_MEM(BPF_B, BPF_REG_7, BPF_REG_0, 7), 398 399 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 400 401 /* sysctl_get_current_value arg3 (buf_len) */ 402 BPF_MOV64_IMM(BPF_REG_3, 7), 403 404 /* sysctl_get_current_value(ctx, buf, buf_len) */ 405 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value), 406 407 /* if (ret == expected && */ 408 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 6, 6), 409 410 /* buf[0:6] == "Linux\n\0") */ 411 BPF_LD_IMM64(BPF_REG_8, 0x000a78756e694cULL), 412 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 413 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 414 415 /* return ALLOW; */ 416 BPF_MOV64_IMM(BPF_REG_0, 1), 417 BPF_JMP_A(1), 418 419 /* else return DENY; */ 420 BPF_MOV64_IMM(BPF_REG_0, 0), 421 BPF_EXIT_INSN(), 422 }, 423 .attach_type = BPF_CGROUP_SYSCTL, 424 .sysctl = "kernel/ostype", 425 .open_flags = O_RDONLY, 426 .result = SUCCESS, 427 }, 428 { 429 .descr = "sysctl_get_current_value sysctl:read E2BIG truncated", 430 .insns = { 431 /* sysctl_get_current_value arg2 (buf) */ 432 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 433 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 434 BPF_MOV64_IMM(BPF_REG_0, 0), 435 BPF_STX_MEM(BPF_H, BPF_REG_7, BPF_REG_0, 6), 436 437 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 438 439 /* sysctl_get_current_value arg3 (buf_len) */ 440 BPF_MOV64_IMM(BPF_REG_3, 6), 441 442 /* sysctl_get_current_value(ctx, buf, buf_len) */ 443 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value), 444 445 /* if (ret == expected && */ 446 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 6), 447 448 /* buf[0:6] == "Linux\0") */ 449 BPF_LD_IMM64(BPF_REG_8, 0x000078756e694cULL), 450 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 451 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 452 453 /* return ALLOW; */ 454 BPF_MOV64_IMM(BPF_REG_0, 1), 455 BPF_JMP_A(1), 456 457 /* else return DENY; */ 458 BPF_MOV64_IMM(BPF_REG_0, 0), 459 BPF_EXIT_INSN(), 460 }, 461 .attach_type = BPF_CGROUP_SYSCTL, 462 .sysctl = "kernel/ostype", 463 .open_flags = O_RDONLY, 464 .result = SUCCESS, 465 }, 466 { 467 .descr = "sysctl_get_current_value sysctl:read EINVAL", 468 .insns = { 469 /* sysctl_get_current_value arg2 (buf) */ 470 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 471 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 472 473 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 474 475 /* sysctl_get_current_value arg3 (buf_len) */ 476 BPF_MOV64_IMM(BPF_REG_3, 8), 477 478 /* sysctl_get_current_value(ctx, buf, buf_len) */ 479 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value), 480 481 /* if (ret == expected && */ 482 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -EINVAL, 4), 483 484 /* buf[0:8] is NUL-filled) */ 485 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 486 BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 0, 2), 487 488 /* return DENY; */ 489 BPF_MOV64_IMM(BPF_REG_0, 0), 490 BPF_JMP_A(1), 491 492 /* else return ALLOW; */ 493 BPF_MOV64_IMM(BPF_REG_0, 1), 494 BPF_EXIT_INSN(), 495 }, 496 .attach_type = BPF_CGROUP_SYSCTL, 497 .sysctl = "net/ipv6/conf/lo/stable_secret", /* -EIO */ 498 .open_flags = O_RDONLY, 499 .result = OP_EPERM, 500 }, 501 { 502 .descr = "sysctl_get_current_value sysctl:write ok", 503 .fixup_value_insn = 6, 504 .insns = { 505 /* sysctl_get_current_value arg2 (buf) */ 506 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), 507 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), 508 509 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), 510 511 /* sysctl_get_current_value arg3 (buf_len) */ 512 BPF_MOV64_IMM(BPF_REG_3, 8), 513 514 /* sysctl_get_current_value(ctx, buf, buf_len) */ 515 BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value), 516 517 /* if (ret == expected && */ 518 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 4, 6), 519 520 /* buf[0:4] == expected) */ 521 BPF_LD_IMM64(BPF_REG_8, FIXUP_SYSCTL_VALUE), 522 BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), 523 BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), 524 525 /* return DENY; */ 526 BPF_MOV64_IMM(BPF_REG_0, 0), 527 BPF_JMP_A(1), 528 529 /* else return ALLOW; */ 530 BPF_MOV64_IMM(BPF_REG_0, 1), 531 BPF_EXIT_INSN(), 532 }, 533 .attach_type = BPF_CGROUP_SYSCTL, 534 .sysctl = "net/ipv4/route/mtu_expires", 535 .open_flags = O_WRONLY, 536 .newval = "600", /* same as default, should fail anyway */ 537 .result = OP_EPERM, 538 }, 539 }; 540 541 static size_t probe_prog_length(const struct bpf_insn *fp) 542 { 543 size_t len; 544 545 for (len = MAX_INSNS - 1; len > 0; --len) 546 if (fp[len].code != 0 || fp[len].imm != 0) 547 break; 548 return len + 1; 549 } 550 551 static int fixup_sysctl_value(const char *buf, size_t buf_len, 552 struct bpf_insn *prog, size_t insn_num) 553 { 554 uint32_t value_num = 0; 555 uint8_t c, i; 556 557 if (buf_len > sizeof(value_num)) { 558 log_err("Value is too big (%zd) to use in fixup", buf_len); 559 return -1; 560 } 561 562 for (i = 0; i < buf_len; ++i) { 563 c = buf[i]; 564 value_num |= (c << i * 8); 565 } 566 567 prog[insn_num].imm = value_num; 568 569 return 0; 570 } 571 572 static int load_sysctl_prog(struct sysctl_test *test, const char *sysctl_path) 573 { 574 struct bpf_insn *prog = test->insns; 575 struct bpf_load_program_attr attr; 576 int ret; 577 578 memset(&attr, 0, sizeof(struct bpf_load_program_attr)); 579 attr.prog_type = BPF_PROG_TYPE_CGROUP_SYSCTL; 580 attr.insns = prog; 581 attr.insns_cnt = probe_prog_length(attr.insns); 582 attr.license = "GPL"; 583 584 if (test->fixup_value_insn) { 585 char buf[128]; 586 ssize_t len; 587 int fd; 588 589 fd = open(sysctl_path, O_RDONLY | O_CLOEXEC); 590 if (fd < 0) { 591 log_err("open(%s) failed", sysctl_path); 592 return -1; 593 } 594 len = read(fd, buf, sizeof(buf)); 595 if (len == -1) { 596 log_err("read(%s) failed", sysctl_path); 597 close(fd); 598 return -1; 599 } 600 close(fd); 601 if (fixup_sysctl_value(buf, len, prog, test->fixup_value_insn)) 602 return -1; 603 } 604 605 ret = bpf_load_program_xattr(&attr, bpf_log_buf, BPF_LOG_BUF_SIZE); 606 if (ret < 0 && test->result != LOAD_REJECT) { 607 log_err(">>> Loading program error.\n" 608 ">>> Verifier output:\n%s\n-------\n", bpf_log_buf); 609 } 610 611 return ret; 612 } 613 614 static int access_sysctl(const char *sysctl_path, 615 const struct sysctl_test *test) 616 { 617 int err = 0; 618 int fd; 619 620 fd = open(sysctl_path, test->open_flags | O_CLOEXEC); 621 if (fd < 0) 622 return fd; 623 624 if (test->open_flags == O_RDONLY) { 625 char buf[128]; 626 627 if (read(fd, buf, sizeof(buf)) == -1) 628 goto err; 629 } else if (test->open_flags == O_WRONLY) { 630 if (!test->newval) { 631 log_err("New value for sysctl is not set"); 632 goto err; 633 } 634 if (write(fd, test->newval, strlen(test->newval)) == -1) 635 goto err; 636 } else { 637 log_err("Unexpected sysctl access: neither read nor write"); 638 goto err; 639 } 640 641 goto out; 642 err: 643 err = -1; 644 out: 645 close(fd); 646 return err; 647 } 648 649 static int run_test_case(int cgfd, struct sysctl_test *test) 650 { 651 enum bpf_attach_type atype = test->attach_type; 652 char sysctl_path[128]; 653 int progfd = -1; 654 int err = 0; 655 656 printf("Test case: %s .. ", test->descr); 657 658 snprintf(sysctl_path, sizeof(sysctl_path), "/proc/sys/%s", 659 test->sysctl); 660 661 progfd = load_sysctl_prog(test, sysctl_path); 662 if (progfd < 0) { 663 if (test->result == LOAD_REJECT) 664 goto out; 665 else 666 goto err; 667 } 668 669 if (bpf_prog_attach(progfd, cgfd, atype, BPF_F_ALLOW_OVERRIDE) == -1) { 670 if (test->result == ATTACH_REJECT) 671 goto out; 672 else 673 goto err; 674 } 675 676 if (access_sysctl(sysctl_path, test) == -1) { 677 if (test->result == OP_EPERM && errno == EPERM) 678 goto out; 679 else 680 goto err; 681 } 682 683 if (test->result != SUCCESS) { 684 log_err("Unexpected failure"); 685 goto err; 686 } 687 688 goto out; 689 err: 690 err = -1; 691 out: 692 /* Detaching w/o checking return code: best effort attempt. */ 693 if (progfd != -1) 694 bpf_prog_detach(cgfd, atype); 695 close(progfd); 696 printf("[%s]\n", err ? "FAIL" : "PASS"); 697 return err; 698 } 699 700 static int run_tests(int cgfd) 701 { 702 int passes = 0; 703 int fails = 0; 704 int i; 705 706 for (i = 0; i < ARRAY_SIZE(tests); ++i) { 707 if (run_test_case(cgfd, &tests[i])) 708 ++fails; 709 else 710 ++passes; 711 } 712 printf("Summary: %d PASSED, %d FAILED\n", passes, fails); 713 return fails ? -1 : 0; 714 } 715 716 int main(int argc, char **argv) 717 { 718 int cgfd = -1; 719 int err = 0; 720 721 if (setup_cgroup_environment()) 722 goto err; 723 724 cgfd = create_and_get_cgroup(CG_PATH); 725 if (cgfd < 0) 726 goto err; 727 728 if (join_cgroup(CG_PATH)) 729 goto err; 730 731 if (run_tests(cgfd)) 732 goto err; 733 734 goto out; 735 err: 736 err = -1; 737 out: 738 close(cgfd); 739 cleanup_cgroup_environment(); 740 return err; 741 } 742