kernel/bpf/bpf_lsm.c

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