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
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
BTF_SET_END(bpf_lsm_hooks)36 BTF_SET_END(bpf_lsm_hooks)
37
38 int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog,
39 const struct bpf_prog *prog)
40 {
41 if (!prog->gpl_compatible) {
42 bpf_log(vlog,
43 "LSM programs must have a GPL compatible license\n");
44 return -EINVAL;
45 }
46
47 if (!btf_id_set_contains(&bpf_lsm_hooks, prog->aux->attach_btf_id)) {
48 bpf_log(vlog, "attach_btf_id %u points to wrong type name %s\n",
49 prog->aux->attach_btf_id, prog->aux->attach_func_name);
50 return -EINVAL;
51 }
52
53 return 0;
54 }
55
56 /* Mask for all the currently supported BPRM option flags */
57 #define BPF_F_BRPM_OPTS_MASK BPF_F_BPRM_SECUREEXEC
58
BPF_CALL_2(bpf_bprm_opts_set,struct linux_binprm *,bprm,u64,flags)59 BPF_CALL_2(bpf_bprm_opts_set, struct linux_binprm *, bprm, u64, flags)
60 {
61 if (flags & ~BPF_F_BRPM_OPTS_MASK)
62 return -EINVAL;
63
64 bprm->secureexec = (flags & BPF_F_BPRM_SECUREEXEC);
65 return 0;
66 }
67
68 BTF_ID_LIST_SINGLE(bpf_bprm_opts_set_btf_ids, struct, linux_binprm)
69
70 static const struct bpf_func_proto bpf_bprm_opts_set_proto = {
71 .func = bpf_bprm_opts_set,
72 .gpl_only = false,
73 .ret_type = RET_INTEGER,
74 .arg1_type = ARG_PTR_TO_BTF_ID,
75 .arg1_btf_id = &bpf_bprm_opts_set_btf_ids[0],
76 .arg2_type = ARG_ANYTHING,
77 };
78
BPF_CALL_3(bpf_ima_inode_hash,struct inode *,inode,void *,dst,u32,size)79 BPF_CALL_3(bpf_ima_inode_hash, struct inode *, inode, void *, dst, u32, size)
80 {
81 return ima_inode_hash(inode, dst, size);
82 }
83
bpf_ima_inode_hash_allowed(const struct bpf_prog * prog)84 static bool bpf_ima_inode_hash_allowed(const struct bpf_prog *prog)
85 {
86 return bpf_lsm_is_sleepable_hook(prog->aux->attach_btf_id);
87 }
88
89 BTF_ID_LIST_SINGLE(bpf_ima_inode_hash_btf_ids, struct, inode)
90
91 static const struct bpf_func_proto bpf_ima_inode_hash_proto = {
92 .func = bpf_ima_inode_hash,
93 .gpl_only = false,
94 .ret_type = RET_INTEGER,
95 .arg1_type = ARG_PTR_TO_BTF_ID,
96 .arg1_btf_id = &bpf_ima_inode_hash_btf_ids[0],
97 .arg2_type = ARG_PTR_TO_UNINIT_MEM,
98 .arg3_type = ARG_CONST_SIZE,
99 .allowed = bpf_ima_inode_hash_allowed,
100 };
101
BPF_CALL_3(bpf_ima_file_hash,struct file *,file,void *,dst,u32,size)102 BPF_CALL_3(bpf_ima_file_hash, struct file *, file, void *, dst, u32, size)
103 {
104 return ima_file_hash(file, dst, size);
105 }
106
107 BTF_ID_LIST_SINGLE(bpf_ima_file_hash_btf_ids, struct, file)
108
109 static const struct bpf_func_proto bpf_ima_file_hash_proto = {
110 .func = bpf_ima_file_hash,
111 .gpl_only = false,
112 .ret_type = RET_INTEGER,
113 .arg1_type = ARG_PTR_TO_BTF_ID,
114 .arg1_btf_id = &bpf_ima_file_hash_btf_ids[0],
115 .arg2_type = ARG_PTR_TO_UNINIT_MEM,
116 .arg3_type = ARG_CONST_SIZE,
117 .allowed = bpf_ima_inode_hash_allowed,
118 };
119
BPF_CALL_1(bpf_get_attach_cookie,void *,ctx)120 BPF_CALL_1(bpf_get_attach_cookie, void *, ctx)
121 {
122 struct bpf_trace_run_ctx *run_ctx;
123
124 run_ctx = container_of(current->bpf_ctx, struct bpf_trace_run_ctx, run_ctx);
125 return run_ctx->bpf_cookie;
126 }
127
128 static const struct bpf_func_proto bpf_get_attach_cookie_proto = {
129 .func = bpf_get_attach_cookie,
130 .gpl_only = false,
131 .ret_type = RET_INTEGER,
132 .arg1_type = ARG_PTR_TO_CTX,
133 };
134
135 static const struct bpf_func_proto *
bpf_lsm_func_proto(enum bpf_func_id func_id,const struct bpf_prog * prog)136 bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
137 {
138 switch (func_id) {
139 case BPF_FUNC_inode_storage_get:
140 return &bpf_inode_storage_get_proto;
141 case BPF_FUNC_inode_storage_delete:
142 return &bpf_inode_storage_delete_proto;
143 #ifdef CONFIG_NET
144 case BPF_FUNC_sk_storage_get:
145 return &bpf_sk_storage_get_proto;
146 case BPF_FUNC_sk_storage_delete:
147 return &bpf_sk_storage_delete_proto;
148 #endif /* CONFIG_NET */
149 case BPF_FUNC_spin_lock:
150 return &bpf_spin_lock_proto;
151 case BPF_FUNC_spin_unlock:
152 return &bpf_spin_unlock_proto;
153 case BPF_FUNC_bprm_opts_set:
154 return &bpf_bprm_opts_set_proto;
155 case BPF_FUNC_ima_inode_hash:
156 return prog->aux->sleepable ? &bpf_ima_inode_hash_proto : NULL;
157 case BPF_FUNC_ima_file_hash:
158 return prog->aux->sleepable ? &bpf_ima_file_hash_proto : NULL;
159 case BPF_FUNC_get_attach_cookie:
160 return bpf_prog_has_trampoline(prog) ? &bpf_get_attach_cookie_proto : NULL;
161 default:
162 return tracing_prog_func_proto(func_id, prog);
163 }
164 }
165
166 /* The set of hooks which are called without pagefaults disabled and are allowed
167 * to "sleep" and thus can be used for sleepable BPF programs.
168 */
169 BTF_SET_START(sleepable_lsm_hooks)
BTF_ID(func,bpf_lsm_bpf)170 BTF_ID(func, bpf_lsm_bpf)
171 BTF_ID(func, bpf_lsm_bpf_map)
172 BTF_ID(func, bpf_lsm_bpf_map_alloc_security)
173 BTF_ID(func, bpf_lsm_bpf_map_free_security)
174 BTF_ID(func, bpf_lsm_bpf_prog)
175 BTF_ID(func, bpf_lsm_bprm_check_security)
176 BTF_ID(func, bpf_lsm_bprm_committed_creds)
177 BTF_ID(func, bpf_lsm_bprm_committing_creds)
178 BTF_ID(func, bpf_lsm_bprm_creds_for_exec)
179 BTF_ID(func, bpf_lsm_bprm_creds_from_file)
180 BTF_ID(func, bpf_lsm_capget)
181 BTF_ID(func, bpf_lsm_capset)
182 BTF_ID(func, bpf_lsm_cred_prepare)
183 BTF_ID(func, bpf_lsm_file_ioctl)
184 BTF_ID(func, bpf_lsm_file_lock)
185 BTF_ID(func, bpf_lsm_file_open)
186 BTF_ID(func, bpf_lsm_file_receive)
187
188 #ifdef CONFIG_SECURITY_NETWORK
189 BTF_ID(func, bpf_lsm_inet_conn_established)
190 #endif /* CONFIG_SECURITY_NETWORK */
191
192 BTF_ID(func, bpf_lsm_inode_create)
193 BTF_ID(func, bpf_lsm_inode_free_security)
194 BTF_ID(func, bpf_lsm_inode_getattr)
195 BTF_ID(func, bpf_lsm_inode_getxattr)
196 BTF_ID(func, bpf_lsm_inode_mknod)
197 BTF_ID(func, bpf_lsm_inode_need_killpriv)
198 BTF_ID(func, bpf_lsm_inode_post_setxattr)
199 BTF_ID(func, bpf_lsm_inode_readlink)
200 BTF_ID(func, bpf_lsm_inode_rename)
201 BTF_ID(func, bpf_lsm_inode_rmdir)
202 BTF_ID(func, bpf_lsm_inode_setattr)
203 BTF_ID(func, bpf_lsm_inode_setxattr)
204 BTF_ID(func, bpf_lsm_inode_symlink)
205 BTF_ID(func, bpf_lsm_inode_unlink)
206 BTF_ID(func, bpf_lsm_kernel_module_request)
207 BTF_ID(func, bpf_lsm_kernel_read_file)
208 BTF_ID(func, bpf_lsm_kernfs_init_security)
209
210 #ifdef CONFIG_KEYS
211 BTF_ID(func, bpf_lsm_key_free)
212 #endif /* CONFIG_KEYS */
213
214 BTF_ID(func, bpf_lsm_mmap_file)
215 BTF_ID(func, bpf_lsm_netlink_send)
216 BTF_ID(func, bpf_lsm_path_notify)
217 BTF_ID(func, bpf_lsm_release_secctx)
218 BTF_ID(func, bpf_lsm_sb_alloc_security)
219 BTF_ID(func, bpf_lsm_sb_eat_lsm_opts)
220 BTF_ID(func, bpf_lsm_sb_kern_mount)
221 BTF_ID(func, bpf_lsm_sb_mount)
222 BTF_ID(func, bpf_lsm_sb_remount)
223 BTF_ID(func, bpf_lsm_sb_set_mnt_opts)
224 BTF_ID(func, bpf_lsm_sb_show_options)
225 BTF_ID(func, bpf_lsm_sb_statfs)
226 BTF_ID(func, bpf_lsm_sb_umount)
227 BTF_ID(func, bpf_lsm_settime)
228
229 #ifdef CONFIG_SECURITY_NETWORK
230 BTF_ID(func, bpf_lsm_socket_accept)
231 BTF_ID(func, bpf_lsm_socket_bind)
232 BTF_ID(func, bpf_lsm_socket_connect)
233 BTF_ID(func, bpf_lsm_socket_create)
234 BTF_ID(func, bpf_lsm_socket_getpeername)
235 BTF_ID(func, bpf_lsm_socket_getpeersec_dgram)
236 BTF_ID(func, bpf_lsm_socket_getsockname)
237 BTF_ID(func, bpf_lsm_socket_getsockopt)
238 BTF_ID(func, bpf_lsm_socket_listen)
239 BTF_ID(func, bpf_lsm_socket_post_create)
240 BTF_ID(func, bpf_lsm_socket_recvmsg)
241 BTF_ID(func, bpf_lsm_socket_sendmsg)
242 BTF_ID(func, bpf_lsm_socket_shutdown)
243 BTF_ID(func, bpf_lsm_socket_socketpair)
244 #endif /* CONFIG_SECURITY_NETWORK */
245
246 BTF_ID(func, bpf_lsm_syslog)
247 BTF_ID(func, bpf_lsm_task_alloc)
248 BTF_ID(func, bpf_lsm_current_getsecid_subj)
249 BTF_ID(func, bpf_lsm_task_getsecid_obj)
250 BTF_ID(func, bpf_lsm_task_prctl)
251 BTF_ID(func, bpf_lsm_task_setscheduler)
252 BTF_ID(func, bpf_lsm_task_to_inode)
253 BTF_SET_END(sleepable_lsm_hooks)
254
255 bool bpf_lsm_is_sleepable_hook(u32 btf_id)
256 {
257 return btf_id_set_contains(&sleepable_lsm_hooks, btf_id);
258 }
259
260 const struct bpf_prog_ops lsm_prog_ops = {
261 };
262
263 const struct bpf_verifier_ops lsm_verifier_ops = {
264 .get_func_proto = bpf_lsm_func_proto,
265 .is_valid_access = btf_ctx_access,
266 };
267