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 <linux/bpf_verifier.h> 15 #include <net/bpf_sk_storage.h> 16 #include <linux/bpf_local_storage.h> 17 #include <linux/btf_ids.h> 18 #include <linux/ima.h> 19 #include <linux/bpf-cgroup.h> 20 21 /* For every LSM hook that allows attachment of BPF programs, declare a nop 22 * function where a BPF program can be attached. 23 */ 24 #define LSM_HOOK(RET, DEFAULT, NAME, ...) \ 25 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 /* List of LSM hooks that should operate on 'current' cgroup regardless 40 * of function signature. 41 */ 42 BTF_SET_START(bpf_lsm_current_hooks) 43 /* operate on freshly allocated sk without any cgroup association */ 44 #ifdef CONFIG_SECURITY_NETWORK 45 BTF_ID(func, bpf_lsm_sk_alloc_security) 46 BTF_ID(func, bpf_lsm_sk_free_security) 47 #endif 48 BTF_SET_END(bpf_lsm_current_hooks) 49 50 /* List of LSM hooks that trigger while the socket is properly locked. 51 */ 52 BTF_SET_START(bpf_lsm_locked_sockopt_hooks) 53 #ifdef CONFIG_SECURITY_NETWORK 54 BTF_ID(func, bpf_lsm_sock_graft) 55 BTF_ID(func, bpf_lsm_inet_csk_clone) 56 BTF_ID(func, bpf_lsm_inet_conn_established) 57 #endif 58 BTF_SET_END(bpf_lsm_locked_sockopt_hooks) 59 60 /* List of LSM hooks that trigger while the socket is _not_ locked, 61 * but it's ok to call bpf_{g,s}etsockopt because the socket is still 62 * in the early init phase. 63 */ 64 BTF_SET_START(bpf_lsm_unlocked_sockopt_hooks) 65 #ifdef CONFIG_SECURITY_NETWORK 66 BTF_ID(func, bpf_lsm_socket_post_create) 67 BTF_ID(func, bpf_lsm_socket_socketpair) 68 #endif 69 BTF_SET_END(bpf_lsm_unlocked_sockopt_hooks) 70 71 #ifdef CONFIG_CGROUP_BPF 72 void bpf_lsm_find_cgroup_shim(const struct bpf_prog *prog, 73 bpf_func_t *bpf_func) 74 { 75 const struct btf_param *args __maybe_unused; 76 77 if (btf_type_vlen(prog->aux->attach_func_proto) < 1 || 78 btf_id_set_contains(&bpf_lsm_current_hooks, 79 prog->aux->attach_btf_id)) { 80 *bpf_func = __cgroup_bpf_run_lsm_current; 81 return; 82 } 83 84 #ifdef CONFIG_NET 85 args = btf_params(prog->aux->attach_func_proto); 86 87 if (args[0].type == btf_sock_ids[BTF_SOCK_TYPE_SOCKET]) 88 *bpf_func = __cgroup_bpf_run_lsm_socket; 89 else if (args[0].type == btf_sock_ids[BTF_SOCK_TYPE_SOCK]) 90 *bpf_func = __cgroup_bpf_run_lsm_sock; 91 else 92 #endif 93 *bpf_func = __cgroup_bpf_run_lsm_current; 94 } 95 #endif 96 97 int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog, 98 const struct bpf_prog *prog) 99 { 100 if (!prog->gpl_compatible) { 101 bpf_log(vlog, 102 "LSM programs must have a GPL compatible license\n"); 103 return -EINVAL; 104 } 105 106 if (!btf_id_set_contains(&bpf_lsm_hooks, prog->aux->attach_btf_id)) { 107 bpf_log(vlog, "attach_btf_id %u points to wrong type name %s\n", 108 prog->aux->attach_btf_id, prog->aux->attach_func_name); 109 return -EINVAL; 110 } 111 112 return 0; 113 } 114 115 /* Mask for all the currently supported BPRM option flags */ 116 #define BPF_F_BRPM_OPTS_MASK BPF_F_BPRM_SECUREEXEC 117 118 BPF_CALL_2(bpf_bprm_opts_set, struct linux_binprm *, bprm, u64, flags) 119 { 120 if (flags & ~BPF_F_BRPM_OPTS_MASK) 121 return -EINVAL; 122 123 bprm->secureexec = (flags & BPF_F_BPRM_SECUREEXEC); 124 return 0; 125 } 126 127 BTF_ID_LIST_SINGLE(bpf_bprm_opts_set_btf_ids, struct, linux_binprm) 128 129 static const struct bpf_func_proto bpf_bprm_opts_set_proto = { 130 .func = bpf_bprm_opts_set, 131 .gpl_only = false, 132 .ret_type = RET_INTEGER, 133 .arg1_type = ARG_PTR_TO_BTF_ID, 134 .arg1_btf_id = &bpf_bprm_opts_set_btf_ids[0], 135 .arg2_type = ARG_ANYTHING, 136 }; 137 138 BPF_CALL_3(bpf_ima_inode_hash, struct inode *, inode, void *, dst, u32, size) 139 { 140 return ima_inode_hash(inode, dst, size); 141 } 142 143 static bool bpf_ima_inode_hash_allowed(const struct bpf_prog *prog) 144 { 145 return bpf_lsm_is_sleepable_hook(prog->aux->attach_btf_id); 146 } 147 148 BTF_ID_LIST_SINGLE(bpf_ima_inode_hash_btf_ids, struct, inode) 149 150 static const struct bpf_func_proto bpf_ima_inode_hash_proto = { 151 .func = bpf_ima_inode_hash, 152 .gpl_only = false, 153 .might_sleep = true, 154 .ret_type = RET_INTEGER, 155 .arg1_type = ARG_PTR_TO_BTF_ID, 156 .arg1_btf_id = &bpf_ima_inode_hash_btf_ids[0], 157 .arg2_type = ARG_PTR_TO_UNINIT_MEM, 158 .arg3_type = ARG_CONST_SIZE, 159 .allowed = bpf_ima_inode_hash_allowed, 160 }; 161 162 BPF_CALL_3(bpf_ima_file_hash, struct file *, file, void *, dst, u32, size) 163 { 164 return ima_file_hash(file, dst, size); 165 } 166 167 BTF_ID_LIST_SINGLE(bpf_ima_file_hash_btf_ids, struct, file) 168 169 static const struct bpf_func_proto bpf_ima_file_hash_proto = { 170 .func = bpf_ima_file_hash, 171 .gpl_only = false, 172 .might_sleep = true, 173 .ret_type = RET_INTEGER, 174 .arg1_type = ARG_PTR_TO_BTF_ID, 175 .arg1_btf_id = &bpf_ima_file_hash_btf_ids[0], 176 .arg2_type = ARG_PTR_TO_UNINIT_MEM, 177 .arg3_type = ARG_CONST_SIZE, 178 .allowed = bpf_ima_inode_hash_allowed, 179 }; 180 181 BPF_CALL_1(bpf_get_attach_cookie, void *, ctx) 182 { 183 struct bpf_trace_run_ctx *run_ctx; 184 185 run_ctx = container_of(current->bpf_ctx, struct bpf_trace_run_ctx, run_ctx); 186 return run_ctx->bpf_cookie; 187 } 188 189 static const struct bpf_func_proto bpf_get_attach_cookie_proto = { 190 .func = bpf_get_attach_cookie, 191 .gpl_only = false, 192 .ret_type = RET_INTEGER, 193 .arg1_type = ARG_PTR_TO_CTX, 194 }; 195 196 static const struct bpf_func_proto * 197 bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) 198 { 199 const struct bpf_func_proto *func_proto; 200 201 if (prog->expected_attach_type == BPF_LSM_CGROUP) { 202 func_proto = cgroup_common_func_proto(func_id, prog); 203 if (func_proto) 204 return func_proto; 205 } 206 207 switch (func_id) { 208 case BPF_FUNC_inode_storage_get: 209 return &bpf_inode_storage_get_proto; 210 case BPF_FUNC_inode_storage_delete: 211 return &bpf_inode_storage_delete_proto; 212 #ifdef CONFIG_NET 213 case BPF_FUNC_sk_storage_get: 214 return &bpf_sk_storage_get_proto; 215 case BPF_FUNC_sk_storage_delete: 216 return &bpf_sk_storage_delete_proto; 217 #endif /* CONFIG_NET */ 218 case BPF_FUNC_spin_lock: 219 return &bpf_spin_lock_proto; 220 case BPF_FUNC_spin_unlock: 221 return &bpf_spin_unlock_proto; 222 case BPF_FUNC_bprm_opts_set: 223 return &bpf_bprm_opts_set_proto; 224 case BPF_FUNC_ima_inode_hash: 225 return &bpf_ima_inode_hash_proto; 226 case BPF_FUNC_ima_file_hash: 227 return &bpf_ima_file_hash_proto; 228 case BPF_FUNC_get_attach_cookie: 229 return bpf_prog_has_trampoline(prog) ? &bpf_get_attach_cookie_proto : NULL; 230 #ifdef CONFIG_NET 231 case BPF_FUNC_setsockopt: 232 if (prog->expected_attach_type != BPF_LSM_CGROUP) 233 return NULL; 234 if (btf_id_set_contains(&bpf_lsm_locked_sockopt_hooks, 235 prog->aux->attach_btf_id)) 236 return &bpf_sk_setsockopt_proto; 237 if (btf_id_set_contains(&bpf_lsm_unlocked_sockopt_hooks, 238 prog->aux->attach_btf_id)) 239 return &bpf_unlocked_sk_setsockopt_proto; 240 return NULL; 241 case BPF_FUNC_getsockopt: 242 if (prog->expected_attach_type != BPF_LSM_CGROUP) 243 return NULL; 244 if (btf_id_set_contains(&bpf_lsm_locked_sockopt_hooks, 245 prog->aux->attach_btf_id)) 246 return &bpf_sk_getsockopt_proto; 247 if (btf_id_set_contains(&bpf_lsm_unlocked_sockopt_hooks, 248 prog->aux->attach_btf_id)) 249 return &bpf_unlocked_sk_getsockopt_proto; 250 return NULL; 251 #endif 252 default: 253 return tracing_prog_func_proto(func_id, prog); 254 } 255 } 256 257 /* The set of hooks which are called without pagefaults disabled and are allowed 258 * to "sleep" and thus can be used for sleepable BPF programs. 259 */ 260 BTF_SET_START(sleepable_lsm_hooks) 261 BTF_ID(func, bpf_lsm_bpf) 262 BTF_ID(func, bpf_lsm_bpf_map) 263 BTF_ID(func, bpf_lsm_bpf_map_alloc_security) 264 BTF_ID(func, bpf_lsm_bpf_map_free_security) 265 BTF_ID(func, bpf_lsm_bpf_prog) 266 BTF_ID(func, bpf_lsm_bprm_check_security) 267 BTF_ID(func, bpf_lsm_bprm_committed_creds) 268 BTF_ID(func, bpf_lsm_bprm_committing_creds) 269 BTF_ID(func, bpf_lsm_bprm_creds_for_exec) 270 BTF_ID(func, bpf_lsm_bprm_creds_from_file) 271 BTF_ID(func, bpf_lsm_capget) 272 BTF_ID(func, bpf_lsm_capset) 273 BTF_ID(func, bpf_lsm_cred_prepare) 274 BTF_ID(func, bpf_lsm_file_ioctl) 275 BTF_ID(func, bpf_lsm_file_lock) 276 BTF_ID(func, bpf_lsm_file_open) 277 BTF_ID(func, bpf_lsm_file_receive) 278 279 #ifdef CONFIG_SECURITY_NETWORK 280 BTF_ID(func, bpf_lsm_inet_conn_established) 281 #endif /* CONFIG_SECURITY_NETWORK */ 282 283 BTF_ID(func, bpf_lsm_inode_create) 284 BTF_ID(func, bpf_lsm_inode_free_security) 285 BTF_ID(func, bpf_lsm_inode_getattr) 286 BTF_ID(func, bpf_lsm_inode_getxattr) 287 BTF_ID(func, bpf_lsm_inode_mknod) 288 BTF_ID(func, bpf_lsm_inode_need_killpriv) 289 BTF_ID(func, bpf_lsm_inode_post_setxattr) 290 BTF_ID(func, bpf_lsm_inode_readlink) 291 BTF_ID(func, bpf_lsm_inode_rename) 292 BTF_ID(func, bpf_lsm_inode_rmdir) 293 BTF_ID(func, bpf_lsm_inode_setattr) 294 BTF_ID(func, bpf_lsm_inode_setxattr) 295 BTF_ID(func, bpf_lsm_inode_symlink) 296 BTF_ID(func, bpf_lsm_inode_unlink) 297 BTF_ID(func, bpf_lsm_kernel_module_request) 298 BTF_ID(func, bpf_lsm_kernel_read_file) 299 BTF_ID(func, bpf_lsm_kernfs_init_security) 300 301 #ifdef CONFIG_KEYS 302 BTF_ID(func, bpf_lsm_key_free) 303 #endif /* CONFIG_KEYS */ 304 305 BTF_ID(func, bpf_lsm_mmap_file) 306 BTF_ID(func, bpf_lsm_netlink_send) 307 BTF_ID(func, bpf_lsm_path_notify) 308 BTF_ID(func, bpf_lsm_release_secctx) 309 BTF_ID(func, bpf_lsm_sb_alloc_security) 310 BTF_ID(func, bpf_lsm_sb_eat_lsm_opts) 311 BTF_ID(func, bpf_lsm_sb_kern_mount) 312 BTF_ID(func, bpf_lsm_sb_mount) 313 BTF_ID(func, bpf_lsm_sb_remount) 314 BTF_ID(func, bpf_lsm_sb_set_mnt_opts) 315 BTF_ID(func, bpf_lsm_sb_show_options) 316 BTF_ID(func, bpf_lsm_sb_statfs) 317 BTF_ID(func, bpf_lsm_sb_umount) 318 BTF_ID(func, bpf_lsm_settime) 319 320 #ifdef CONFIG_SECURITY_NETWORK 321 BTF_ID(func, bpf_lsm_socket_accept) 322 BTF_ID(func, bpf_lsm_socket_bind) 323 BTF_ID(func, bpf_lsm_socket_connect) 324 BTF_ID(func, bpf_lsm_socket_create) 325 BTF_ID(func, bpf_lsm_socket_getpeername) 326 BTF_ID(func, bpf_lsm_socket_getpeersec_dgram) 327 BTF_ID(func, bpf_lsm_socket_getsockname) 328 BTF_ID(func, bpf_lsm_socket_getsockopt) 329 BTF_ID(func, bpf_lsm_socket_listen) 330 BTF_ID(func, bpf_lsm_socket_post_create) 331 BTF_ID(func, bpf_lsm_socket_recvmsg) 332 BTF_ID(func, bpf_lsm_socket_sendmsg) 333 BTF_ID(func, bpf_lsm_socket_shutdown) 334 BTF_ID(func, bpf_lsm_socket_socketpair) 335 #endif /* CONFIG_SECURITY_NETWORK */ 336 337 BTF_ID(func, bpf_lsm_syslog) 338 BTF_ID(func, bpf_lsm_task_alloc) 339 BTF_ID(func, bpf_lsm_current_getsecid_subj) 340 BTF_ID(func, bpf_lsm_task_getsecid_obj) 341 BTF_ID(func, bpf_lsm_task_prctl) 342 BTF_ID(func, bpf_lsm_task_setscheduler) 343 BTF_ID(func, bpf_lsm_task_to_inode) 344 BTF_ID(func, bpf_lsm_userns_create) 345 BTF_SET_END(sleepable_lsm_hooks) 346 347 BTF_SET_START(untrusted_lsm_hooks) 348 BTF_ID(func, bpf_lsm_bpf_map_free_security) 349 BTF_ID(func, bpf_lsm_bpf_prog_alloc_security) 350 BTF_ID(func, bpf_lsm_bpf_prog_free_security) 351 BTF_ID(func, bpf_lsm_file_alloc_security) 352 BTF_ID(func, bpf_lsm_file_free_security) 353 #ifdef CONFIG_SECURITY_NETWORK 354 BTF_ID(func, bpf_lsm_sk_alloc_security) 355 BTF_ID(func, bpf_lsm_sk_free_security) 356 #endif /* CONFIG_SECURITY_NETWORK */ 357 BTF_ID(func, bpf_lsm_task_free) 358 BTF_SET_END(untrusted_lsm_hooks) 359 360 bool bpf_lsm_is_sleepable_hook(u32 btf_id) 361 { 362 return btf_id_set_contains(&sleepable_lsm_hooks, btf_id); 363 } 364 365 bool bpf_lsm_is_trusted(const struct bpf_prog *prog) 366 { 367 return !btf_id_set_contains(&untrusted_lsm_hooks, prog->aux->attach_btf_id); 368 } 369 370 const struct bpf_prog_ops lsm_prog_ops = { 371 }; 372 373 const struct bpf_verifier_ops lsm_verifier_ops = { 374 .get_func_proto = bpf_lsm_func_proto, 375 .is_valid_access = btf_ctx_access, 376 }; 377