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