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