1 // SPDX-License-Identifier: GPL-2.0 2 3 /* 4 * Copyright (C) 2020 Google LLC. 5 */ 6 7 #include <linux/filter.h> 8 #include <linux/bpf.h> 9 #include <linux/btf.h> 10 #include <linux/binfmts.h> 11 #include <linux/lsm_hooks.h> 12 #include <linux/bpf_lsm.h> 13 #include <linux/kallsyms.h> 14 #include <net/bpf_sk_storage.h> 15 #include <linux/bpf_local_storage.h> 16 #include <linux/btf_ids.h> 17 #include <linux/ima.h> 18 #include <linux/bpf-cgroup.h> 19 20 /* For every LSM hook that allows attachment of BPF programs, declare a nop 21 * function where a BPF program can be attached. Notably, we qualify each with 22 * weak linkage such that strong overrides can be implemented if need be. 23 */ 24 #define LSM_HOOK(RET, DEFAULT, NAME, ...) \ 25 __weak noinline RET bpf_lsm_##NAME(__VA_ARGS__) \ 26 { \ 27 return DEFAULT; \ 28 } 29 30 #include <linux/lsm_hook_defs.h> 31 #undef LSM_HOOK 32 33 #define LSM_HOOK(RET, DEFAULT, NAME, ...) BTF_ID(func, bpf_lsm_##NAME) 34 BTF_SET_START(bpf_lsm_hooks) 35 #include <linux/lsm_hook_defs.h> 36 #undef LSM_HOOK 37 BTF_SET_END(bpf_lsm_hooks) 38 39 BTF_SET_START(bpf_lsm_disabled_hooks) 40 BTF_ID(func, bpf_lsm_vm_enough_memory) 41 BTF_ID(func, bpf_lsm_inode_need_killpriv) 42 BTF_ID(func, bpf_lsm_inode_getsecurity) 43 BTF_ID(func, bpf_lsm_inode_listsecurity) 44 BTF_ID(func, bpf_lsm_inode_copy_up_xattr) 45 BTF_ID(func, bpf_lsm_getselfattr) 46 BTF_ID(func, bpf_lsm_getprocattr) 47 BTF_ID(func, bpf_lsm_setprocattr) 48 #ifdef CONFIG_KEYS 49 BTF_ID(func, bpf_lsm_key_getsecurity) 50 #endif 51 #ifdef CONFIG_AUDIT 52 BTF_ID(func, bpf_lsm_audit_rule_match) 53 #endif 54 #ifdef CONFIG_SECURITY_NETWORK_XFRM 55 BTF_ID(func, bpf_lsm_xfrm_decode_session) 56 #endif 57 BTF_ID(func, bpf_lsm_ismaclabel) 58 BTF_ID(func, bpf_lsm_file_alloc_security) 59 BTF_SET_END(bpf_lsm_disabled_hooks) 60 61 /* List of LSM hooks that should operate on 'current' cgroup regardless 62 * of function signature. 63 */ 64 BTF_SET_START(bpf_lsm_current_hooks) 65 /* operate on freshly allocated sk without any cgroup association */ 66 #ifdef CONFIG_SECURITY_NETWORK 67 BTF_ID(func, bpf_lsm_sk_alloc_security) 68 BTF_ID(func, bpf_lsm_sk_free_security) 69 #endif 70 BTF_SET_END(bpf_lsm_current_hooks) 71 72 /* List of LSM hooks that trigger while the socket is properly locked. 73 */ 74 BTF_SET_START(bpf_lsm_locked_sockopt_hooks) 75 #ifdef CONFIG_SECURITY_NETWORK 76 BTF_ID(func, bpf_lsm_sock_graft) 77 BTF_ID(func, bpf_lsm_inet_csk_clone) 78 BTF_ID(func, bpf_lsm_inet_conn_established) 79 #endif 80 BTF_SET_END(bpf_lsm_locked_sockopt_hooks) 81 82 /* List of LSM hooks that trigger while the socket is _not_ locked, 83 * but it's ok to call bpf_{g,s}etsockopt because the socket is still 84 * in the early init phase. 85 */ 86 BTF_SET_START(bpf_lsm_unlocked_sockopt_hooks) 87 #ifdef CONFIG_SECURITY_NETWORK 88 BTF_ID(func, bpf_lsm_socket_post_create) 89 BTF_ID(func, bpf_lsm_socket_socketpair) 90 #endif 91 BTF_SET_END(bpf_lsm_unlocked_sockopt_hooks) 92 93 #ifdef CONFIG_CGROUP_BPF 94 void bpf_lsm_find_cgroup_shim(const struct bpf_prog *prog, 95 bpf_func_t *bpf_func) 96 { 97 const struct btf_param *args __maybe_unused; 98 99 if (btf_type_vlen(prog->aux->attach_func_proto) < 1 || 100 btf_id_set_contains(&bpf_lsm_current_hooks, 101 prog->aux->attach_btf_id)) { 102 *bpf_func = __cgroup_bpf_run_lsm_current; 103 return; 104 } 105 106 #ifdef CONFIG_NET 107 args = btf_params(prog->aux->attach_func_proto); 108 109 if (args[0].type == btf_sock_ids[BTF_SOCK_TYPE_SOCKET]) 110 *bpf_func = __cgroup_bpf_run_lsm_socket; 111 else if (args[0].type == btf_sock_ids[BTF_SOCK_TYPE_SOCK]) 112 *bpf_func = __cgroup_bpf_run_lsm_sock; 113 else 114 #endif 115 *bpf_func = __cgroup_bpf_run_lsm_current; 116 } 117 #endif 118 119 int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog, 120 const struct bpf_prog *prog) 121 { 122 u32 btf_id = prog->aux->attach_btf_id; 123 const char *func_name = prog->aux->attach_func_name; 124 125 if (!prog->gpl_compatible) { 126 bpf_log(vlog, 127 "LSM programs must have a GPL compatible license\n"); 128 return -EINVAL; 129 } 130 131 if (btf_id_set_contains(&bpf_lsm_disabled_hooks, btf_id)) { 132 bpf_log(vlog, "attach_btf_id %u points to disabled hook %s\n", 133 btf_id, func_name); 134 return -EINVAL; 135 } 136 137 if (!btf_id_set_contains(&bpf_lsm_hooks, btf_id)) { 138 bpf_log(vlog, "attach_btf_id %u points to wrong type name %s\n", 139 btf_id, func_name); 140 return -EINVAL; 141 } 142 143 return 0; 144 } 145 146 /* Mask for all the currently supported BPRM option flags */ 147 #define BPF_F_BRPM_OPTS_MASK BPF_F_BPRM_SECUREEXEC 148 149 BPF_CALL_2(bpf_bprm_opts_set, struct linux_binprm *, bprm, u64, flags) 150 { 151 if (flags & ~BPF_F_BRPM_OPTS_MASK) 152 return -EINVAL; 153 154 bprm->secureexec = (flags & BPF_F_BPRM_SECUREEXEC); 155 return 0; 156 } 157 158 BTF_ID_LIST_SINGLE(bpf_bprm_opts_set_btf_ids, struct, linux_binprm) 159 160 static const struct bpf_func_proto bpf_bprm_opts_set_proto = { 161 .func = bpf_bprm_opts_set, 162 .gpl_only = false, 163 .ret_type = RET_INTEGER, 164 .arg1_type = ARG_PTR_TO_BTF_ID, 165 .arg1_btf_id = &bpf_bprm_opts_set_btf_ids[0], 166 .arg2_type = ARG_ANYTHING, 167 }; 168 169 BPF_CALL_3(bpf_ima_inode_hash, struct inode *, inode, void *, dst, u32, size) 170 { 171 return ima_inode_hash(inode, dst, size); 172 } 173 174 static bool bpf_ima_inode_hash_allowed(const struct bpf_prog *prog) 175 { 176 return bpf_lsm_is_sleepable_hook(prog->aux->attach_btf_id); 177 } 178 179 BTF_ID_LIST_SINGLE(bpf_ima_inode_hash_btf_ids, struct, inode) 180 181 static const struct bpf_func_proto bpf_ima_inode_hash_proto = { 182 .func = bpf_ima_inode_hash, 183 .gpl_only = false, 184 .might_sleep = true, 185 .ret_type = RET_INTEGER, 186 .arg1_type = ARG_PTR_TO_BTF_ID, 187 .arg1_btf_id = &bpf_ima_inode_hash_btf_ids[0], 188 .arg2_type = ARG_PTR_TO_UNINIT_MEM, 189 .arg3_type = ARG_CONST_SIZE, 190 .allowed = bpf_ima_inode_hash_allowed, 191 }; 192 193 BPF_CALL_3(bpf_ima_file_hash, struct file *, file, void *, dst, u32, size) 194 { 195 return ima_file_hash(file, dst, size); 196 } 197 198 BTF_ID_LIST_SINGLE(bpf_ima_file_hash_btf_ids, struct, file) 199 200 static const struct bpf_func_proto bpf_ima_file_hash_proto = { 201 .func = bpf_ima_file_hash, 202 .gpl_only = false, 203 .might_sleep = true, 204 .ret_type = RET_INTEGER, 205 .arg1_type = ARG_PTR_TO_BTF_ID, 206 .arg1_btf_id = &bpf_ima_file_hash_btf_ids[0], 207 .arg2_type = ARG_PTR_TO_UNINIT_MEM, 208 .arg3_type = ARG_CONST_SIZE, 209 .allowed = bpf_ima_inode_hash_allowed, 210 }; 211 212 BPF_CALL_1(bpf_get_attach_cookie, void *, ctx) 213 { 214 struct bpf_trace_run_ctx *run_ctx; 215 216 run_ctx = container_of(current->bpf_ctx, struct bpf_trace_run_ctx, run_ctx); 217 return run_ctx->bpf_cookie; 218 } 219 220 static const struct bpf_func_proto bpf_get_attach_cookie_proto = { 221 .func = bpf_get_attach_cookie, 222 .gpl_only = false, 223 .ret_type = RET_INTEGER, 224 .arg1_type = ARG_PTR_TO_CTX, 225 }; 226 227 static const struct bpf_func_proto * 228 bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) 229 { 230 const struct bpf_func_proto *func_proto; 231 232 if (prog->expected_attach_type == BPF_LSM_CGROUP) { 233 func_proto = cgroup_common_func_proto(func_id, prog); 234 if (func_proto) 235 return func_proto; 236 } 237 238 switch (func_id) { 239 case BPF_FUNC_inode_storage_get: 240 return &bpf_inode_storage_get_proto; 241 case BPF_FUNC_inode_storage_delete: 242 return &bpf_inode_storage_delete_proto; 243 #ifdef CONFIG_NET 244 case BPF_FUNC_sk_storage_get: 245 return &bpf_sk_storage_get_proto; 246 case BPF_FUNC_sk_storage_delete: 247 return &bpf_sk_storage_delete_proto; 248 #endif /* CONFIG_NET */ 249 case BPF_FUNC_spin_lock: 250 return &bpf_spin_lock_proto; 251 case BPF_FUNC_spin_unlock: 252 return &bpf_spin_unlock_proto; 253 case BPF_FUNC_bprm_opts_set: 254 return &bpf_bprm_opts_set_proto; 255 case BPF_FUNC_ima_inode_hash: 256 return &bpf_ima_inode_hash_proto; 257 case BPF_FUNC_ima_file_hash: 258 return &bpf_ima_file_hash_proto; 259 case BPF_FUNC_get_attach_cookie: 260 return bpf_prog_has_trampoline(prog) ? &bpf_get_attach_cookie_proto : NULL; 261 #ifdef CONFIG_NET 262 case BPF_FUNC_setsockopt: 263 if (prog->expected_attach_type != BPF_LSM_CGROUP) 264 return NULL; 265 if (btf_id_set_contains(&bpf_lsm_locked_sockopt_hooks, 266 prog->aux->attach_btf_id)) 267 return &bpf_sk_setsockopt_proto; 268 if (btf_id_set_contains(&bpf_lsm_unlocked_sockopt_hooks, 269 prog->aux->attach_btf_id)) 270 return &bpf_unlocked_sk_setsockopt_proto; 271 return NULL; 272 case BPF_FUNC_getsockopt: 273 if (prog->expected_attach_type != BPF_LSM_CGROUP) 274 return NULL; 275 if (btf_id_set_contains(&bpf_lsm_locked_sockopt_hooks, 276 prog->aux->attach_btf_id)) 277 return &bpf_sk_getsockopt_proto; 278 if (btf_id_set_contains(&bpf_lsm_unlocked_sockopt_hooks, 279 prog->aux->attach_btf_id)) 280 return &bpf_unlocked_sk_getsockopt_proto; 281 return NULL; 282 #endif 283 default: 284 return tracing_prog_func_proto(func_id, prog); 285 } 286 } 287 288 /* The set of hooks which are called without pagefaults disabled and are allowed 289 * to "sleep" and thus can be used for sleepable BPF programs. 290 */ 291 BTF_SET_START(sleepable_lsm_hooks) 292 BTF_ID(func, bpf_lsm_bpf) 293 BTF_ID(func, bpf_lsm_bpf_map) 294 BTF_ID(func, bpf_lsm_bpf_map_create) 295 BTF_ID(func, bpf_lsm_bpf_map_free) 296 BTF_ID(func, bpf_lsm_bpf_prog) 297 BTF_ID(func, bpf_lsm_bpf_prog_load) 298 BTF_ID(func, bpf_lsm_bpf_prog_free) 299 BTF_ID(func, bpf_lsm_bpf_token_create) 300 BTF_ID(func, bpf_lsm_bpf_token_free) 301 BTF_ID(func, bpf_lsm_bpf_token_cmd) 302 BTF_ID(func, bpf_lsm_bpf_token_capable) 303 BTF_ID(func, bpf_lsm_bprm_check_security) 304 BTF_ID(func, bpf_lsm_bprm_committed_creds) 305 BTF_ID(func, bpf_lsm_bprm_committing_creds) 306 BTF_ID(func, bpf_lsm_bprm_creds_for_exec) 307 BTF_ID(func, bpf_lsm_bprm_creds_from_file) 308 BTF_ID(func, bpf_lsm_capget) 309 BTF_ID(func, bpf_lsm_capset) 310 BTF_ID(func, bpf_lsm_cred_prepare) 311 BTF_ID(func, bpf_lsm_file_ioctl) 312 BTF_ID(func, bpf_lsm_file_lock) 313 BTF_ID(func, bpf_lsm_file_open) 314 BTF_ID(func, bpf_lsm_file_post_open) 315 BTF_ID(func, bpf_lsm_file_receive) 316 317 BTF_ID(func, bpf_lsm_inode_create) 318 BTF_ID(func, bpf_lsm_inode_free_security) 319 BTF_ID(func, bpf_lsm_inode_getattr) 320 BTF_ID(func, bpf_lsm_inode_getxattr) 321 BTF_ID(func, bpf_lsm_inode_mknod) 322 BTF_ID(func, bpf_lsm_inode_need_killpriv) 323 BTF_ID(func, bpf_lsm_inode_post_setxattr) 324 BTF_ID(func, bpf_lsm_inode_post_removexattr) 325 BTF_ID(func, bpf_lsm_inode_readlink) 326 BTF_ID(func, bpf_lsm_inode_removexattr) 327 BTF_ID(func, bpf_lsm_inode_rename) 328 BTF_ID(func, bpf_lsm_inode_rmdir) 329 BTF_ID(func, bpf_lsm_inode_setattr) 330 BTF_ID(func, bpf_lsm_inode_setxattr) 331 BTF_ID(func, bpf_lsm_inode_symlink) 332 BTF_ID(func, bpf_lsm_inode_unlink) 333 BTF_ID(func, bpf_lsm_kernel_module_request) 334 BTF_ID(func, bpf_lsm_kernel_read_file) 335 BTF_ID(func, bpf_lsm_kernfs_init_security) 336 337 #ifdef CONFIG_SECURITY_PATH 338 BTF_ID(func, bpf_lsm_path_unlink) 339 BTF_ID(func, bpf_lsm_path_mkdir) 340 BTF_ID(func, bpf_lsm_path_rmdir) 341 BTF_ID(func, bpf_lsm_path_truncate) 342 BTF_ID(func, bpf_lsm_path_symlink) 343 BTF_ID(func, bpf_lsm_path_link) 344 BTF_ID(func, bpf_lsm_path_rename) 345 BTF_ID(func, bpf_lsm_path_chmod) 346 BTF_ID(func, bpf_lsm_path_chown) 347 #endif /* CONFIG_SECURITY_PATH */ 348 349 BTF_ID(func, bpf_lsm_mmap_file) 350 BTF_ID(func, bpf_lsm_netlink_send) 351 BTF_ID(func, bpf_lsm_path_notify) 352 BTF_ID(func, bpf_lsm_release_secctx) 353 BTF_ID(func, bpf_lsm_sb_alloc_security) 354 BTF_ID(func, bpf_lsm_sb_eat_lsm_opts) 355 BTF_ID(func, bpf_lsm_sb_kern_mount) 356 BTF_ID(func, bpf_lsm_sb_mount) 357 BTF_ID(func, bpf_lsm_sb_remount) 358 BTF_ID(func, bpf_lsm_sb_set_mnt_opts) 359 BTF_ID(func, bpf_lsm_sb_show_options) 360 BTF_ID(func, bpf_lsm_sb_statfs) 361 BTF_ID(func, bpf_lsm_sb_umount) 362 BTF_ID(func, bpf_lsm_settime) 363 364 #ifdef CONFIG_SECURITY_NETWORK 365 BTF_ID(func, bpf_lsm_socket_accept) 366 BTF_ID(func, bpf_lsm_socket_bind) 367 BTF_ID(func, bpf_lsm_socket_connect) 368 BTF_ID(func, bpf_lsm_socket_create) 369 BTF_ID(func, bpf_lsm_socket_getpeername) 370 BTF_ID(func, bpf_lsm_socket_getpeersec_dgram) 371 BTF_ID(func, bpf_lsm_socket_getsockname) 372 BTF_ID(func, bpf_lsm_socket_getsockopt) 373 BTF_ID(func, bpf_lsm_socket_listen) 374 BTF_ID(func, bpf_lsm_socket_post_create) 375 BTF_ID(func, bpf_lsm_socket_recvmsg) 376 BTF_ID(func, bpf_lsm_socket_sendmsg) 377 BTF_ID(func, bpf_lsm_socket_shutdown) 378 BTF_ID(func, bpf_lsm_socket_socketpair) 379 #endif /* CONFIG_SECURITY_NETWORK */ 380 381 BTF_ID(func, bpf_lsm_syslog) 382 BTF_ID(func, bpf_lsm_task_alloc) 383 BTF_ID(func, bpf_lsm_task_prctl) 384 BTF_ID(func, bpf_lsm_task_setscheduler) 385 BTF_ID(func, bpf_lsm_userns_create) 386 BTF_ID(func, bpf_lsm_bdev_alloc_security) 387 BTF_ID(func, bpf_lsm_bdev_setintegrity) 388 BTF_SET_END(sleepable_lsm_hooks) 389 390 BTF_SET_START(untrusted_lsm_hooks) 391 BTF_ID(func, bpf_lsm_bpf_map_free) 392 BTF_ID(func, bpf_lsm_bpf_prog_free) 393 BTF_ID(func, bpf_lsm_file_alloc_security) 394 BTF_ID(func, bpf_lsm_file_free_security) 395 #ifdef CONFIG_SECURITY_NETWORK 396 BTF_ID(func, bpf_lsm_sk_alloc_security) 397 BTF_ID(func, bpf_lsm_sk_free_security) 398 #endif /* CONFIG_SECURITY_NETWORK */ 399 BTF_ID(func, bpf_lsm_task_free) 400 BTF_ID(func, bpf_lsm_bdev_alloc_security) 401 BTF_ID(func, bpf_lsm_bdev_free_security) 402 BTF_SET_END(untrusted_lsm_hooks) 403 404 bool bpf_lsm_is_sleepable_hook(u32 btf_id) 405 { 406 return btf_id_set_contains(&sleepable_lsm_hooks, btf_id); 407 } 408 409 bool bpf_lsm_is_trusted(const struct bpf_prog *prog) 410 { 411 return !btf_id_set_contains(&untrusted_lsm_hooks, prog->aux->attach_btf_id); 412 } 413 414 const struct bpf_prog_ops lsm_prog_ops = { 415 }; 416 417 const struct bpf_verifier_ops lsm_verifier_ops = { 418 .get_func_proto = bpf_lsm_func_proto, 419 .is_valid_access = btf_ctx_access, 420 }; 421 422 /* hooks return 0 or 1 */ 423 BTF_SET_START(bool_lsm_hooks) 424 #ifdef CONFIG_SECURITY_NETWORK_XFRM 425 BTF_ID(func, bpf_lsm_xfrm_state_pol_flow_match) 426 #endif 427 #ifdef CONFIG_AUDIT 428 BTF_ID(func, bpf_lsm_audit_rule_known) 429 #endif 430 BTF_ID(func, bpf_lsm_inode_xattr_skipcap) 431 BTF_SET_END(bool_lsm_hooks) 432 433 /* hooks returning void */ 434 #define LSM_HOOK_void(DEFAULT, NAME, ...) BTF_ID(func, bpf_lsm_##NAME) 435 #define LSM_HOOK_int(DEFAULT, NAME, ...) /* nothing */ 436 #define LSM_HOOK(RET, DEFAULT, NAME, ...) LSM_HOOK_##RET(DEFAULT, NAME, __VA_ARGS__) 437 BTF_SET_START(void_lsm_hooks) 438 #include <linux/lsm_hook_defs.h> 439 #undef LSM_HOOK 440 #undef LSM_HOOK_void 441 #undef LSM_HOOK_int 442 BTF_SET_END(void_lsm_hooks) 443 444 bool bpf_lsm_hook_returns_errno(u32 btf_id) 445 { 446 if (btf_id_set_contains(&bool_lsm_hooks, btf_id)) 447 return false; 448 if (btf_id_set_contains(&void_lsm_hooks, btf_id)) 449 return false; 450 return true; 451 } 452 453 int bpf_lsm_get_retval_range(const struct bpf_prog *prog, 454 struct bpf_retval_range *retval_range) 455 { 456 /* no return value range for void hooks */ 457 if (!prog->aux->attach_func_proto->type) 458 return -EINVAL; 459 460 if (btf_id_set_contains(&bool_lsm_hooks, prog->aux->attach_btf_id)) { 461 retval_range->minval = 0; 462 retval_range->maxval = 1; 463 } else { 464 /* All other available LSM hooks, except task_prctl, return 0 465 * on success and negative error code on failure. 466 * To keep things simple, we only allow bpf progs to return 0 467 * or negative errno for task_prctl too. 468 */ 469 retval_range->minval = -MAX_ERRNO; 470 retval_range->maxval = 0; 471 } 472 return 0; 473 } 474