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
BTF_SET_END(bpf_lsm_hooks)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
bpf_lsm_verify_prog(struct bpf_verifier_log * vlog,const struct bpf_prog * prog)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
BPF_CALL_2(bpf_bprm_opts_set,struct linux_binprm *,bprm,u64,flags)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
BPF_CALL_3(bpf_ima_inode_hash,struct inode *,inode,void *,dst,u32,size)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
bpf_ima_inode_hash_allowed(const struct bpf_prog * prog)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
BPF_CALL_3(bpf_ima_file_hash,struct file *,file,void *,dst,u32,size)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
BPF_CALL_1(bpf_get_attach_cookie,void *,ctx)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 *
bpf_lsm_func_proto(enum bpf_func_id func_id,const struct bpf_prog * prog)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)
BTF_ID(func,bpf_lsm_bpf)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
bpf_lsm_is_trusted(const struct bpf_prog * prog)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