1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
3
4 #include "vmlinux.h"
5 #include <bpf/bpf_helpers.h>
6 #include <bpf/bpf_tracing.h>
7 #include "bpf_tracing_net.h"
8 #include "bpf_misc.h"
9
10 char _license[] SEC("license") = "GPL";
11
12 struct {
13 __uint(type, BPF_MAP_TYPE_TASK_STORAGE);
14 __uint(map_flags, BPF_F_NO_PREALLOC);
15 __type(key, int);
16 __type(value, long);
17 } map_a SEC(".maps");
18
19 __u32 user_data, key_serial, target_pid;
20 __u64 flags, task_storage_val, cgroup_id;
21
22 struct bpf_key *bpf_lookup_user_key(__u32 serial, __u64 flags) __ksym;
23 void bpf_key_put(struct bpf_key *key) __ksym;
24 void bpf_rcu_read_lock(void) __ksym;
25 void bpf_rcu_read_unlock(void) __ksym;
26 struct task_struct *bpf_task_acquire_not_zero(struct task_struct *p) __ksym;
27 void bpf_task_release(struct task_struct *p) __ksym;
28
29 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
get_cgroup_id(void * ctx)30 int get_cgroup_id(void *ctx)
31 {
32 struct task_struct *task;
33 struct css_set *cgroups;
34
35 task = bpf_get_current_task_btf();
36 if (task->pid != target_pid)
37 return 0;
38
39 /* simulate bpf_get_current_cgroup_id() helper */
40 bpf_rcu_read_lock();
41 cgroups = task->cgroups;
42 if (!cgroups)
43 goto unlock;
44 cgroup_id = cgroups->dfl_cgrp->kn->id;
45 unlock:
46 bpf_rcu_read_unlock();
47 return 0;
48 }
49
50 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
task_succ(void * ctx)51 int task_succ(void *ctx)
52 {
53 struct task_struct *task, *real_parent;
54 long init_val = 2;
55 long *ptr;
56
57 task = bpf_get_current_task_btf();
58 if (task->pid != target_pid)
59 return 0;
60
61 bpf_rcu_read_lock();
62 /* region including helper using rcu ptr real_parent */
63 real_parent = task->real_parent;
64 if (!real_parent)
65 goto out;
66 ptr = bpf_task_storage_get(&map_a, real_parent, &init_val,
67 BPF_LOCAL_STORAGE_GET_F_CREATE);
68 if (!ptr)
69 goto out;
70 ptr = bpf_task_storage_get(&map_a, real_parent, 0, 0);
71 if (!ptr)
72 goto out;
73 task_storage_val = *ptr;
74 out:
75 bpf_rcu_read_unlock();
76 return 0;
77 }
78
79 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
no_lock(void * ctx)80 int no_lock(void *ctx)
81 {
82 struct task_struct *task, *real_parent;
83
84 /* no bpf_rcu_read_lock(), old code still works */
85 task = bpf_get_current_task_btf();
86 real_parent = task->real_parent;
87 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
88 return 0;
89 }
90
91 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
two_regions(void * ctx)92 int two_regions(void *ctx)
93 {
94 struct task_struct *task, *real_parent;
95
96 /* two regions */
97 task = bpf_get_current_task_btf();
98 bpf_rcu_read_lock();
99 bpf_rcu_read_unlock();
100 bpf_rcu_read_lock();
101 real_parent = task->real_parent;
102 if (!real_parent)
103 goto out;
104 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
105 out:
106 bpf_rcu_read_unlock();
107 return 0;
108 }
109
110 SEC("?fentry/" SYS_PREFIX "sys_getpgid")
non_sleepable_1(void * ctx)111 int non_sleepable_1(void *ctx)
112 {
113 struct task_struct *task, *real_parent;
114
115 task = bpf_get_current_task_btf();
116 bpf_rcu_read_lock();
117 real_parent = task->real_parent;
118 if (!real_parent)
119 goto out;
120 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
121 out:
122 bpf_rcu_read_unlock();
123 return 0;
124 }
125
126 SEC("?fentry/" SYS_PREFIX "sys_getpgid")
non_sleepable_2(void * ctx)127 int non_sleepable_2(void *ctx)
128 {
129 struct task_struct *task, *real_parent;
130
131 bpf_rcu_read_lock();
132 task = bpf_get_current_task_btf();
133 bpf_rcu_read_unlock();
134
135 bpf_rcu_read_lock();
136 real_parent = task->real_parent;
137 if (!real_parent)
138 goto out;
139 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
140 out:
141 bpf_rcu_read_unlock();
142 return 0;
143 }
144
145 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
task_acquire(void * ctx)146 int task_acquire(void *ctx)
147 {
148 struct task_struct *task, *real_parent, *gparent;
149
150 task = bpf_get_current_task_btf();
151 bpf_rcu_read_lock();
152 real_parent = task->real_parent;
153 if (!real_parent)
154 goto out;
155
156 /* rcu_ptr->rcu_field */
157 gparent = real_parent->real_parent;
158 if (!gparent)
159 goto out;
160
161 /* acquire a reference which can be used outside rcu read lock region */
162 gparent = bpf_task_acquire_not_zero(gparent);
163 if (!gparent)
164 /* Until we resolve the issues with using task->rcu_users, we
165 * expect bpf_task_acquire_not_zero() to return a NULL task.
166 * See the comment at the definition of
167 * bpf_task_acquire_not_zero() for more details.
168 */
169 goto out;
170
171 (void)bpf_task_storage_get(&map_a, gparent, 0, 0);
172 bpf_task_release(gparent);
173 out:
174 bpf_rcu_read_unlock();
175 return 0;
176 }
177
178 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
miss_lock(void * ctx)179 int miss_lock(void *ctx)
180 {
181 struct task_struct *task;
182 struct css_set *cgroups;
183 struct cgroup *dfl_cgrp;
184
185 /* missing bpf_rcu_read_lock() */
186 task = bpf_get_current_task_btf();
187 bpf_rcu_read_lock();
188 (void)bpf_task_storage_get(&map_a, task, 0, 0);
189 bpf_rcu_read_unlock();
190 bpf_rcu_read_unlock();
191 return 0;
192 }
193
194 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
miss_unlock(void * ctx)195 int miss_unlock(void *ctx)
196 {
197 struct task_struct *task;
198 struct css_set *cgroups;
199 struct cgroup *dfl_cgrp;
200
201 /* missing bpf_rcu_read_unlock() */
202 task = bpf_get_current_task_btf();
203 bpf_rcu_read_lock();
204 (void)bpf_task_storage_get(&map_a, task, 0, 0);
205 return 0;
206 }
207
208 SEC("?fentry/" SYS_PREFIX "sys_getpgid")
non_sleepable_rcu_mismatch(void * ctx)209 int non_sleepable_rcu_mismatch(void *ctx)
210 {
211 struct task_struct *task, *real_parent;
212
213 task = bpf_get_current_task_btf();
214 /* non-sleepable: missing bpf_rcu_read_unlock() in one path */
215 bpf_rcu_read_lock();
216 real_parent = task->real_parent;
217 if (!real_parent)
218 goto out;
219 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
220 if (real_parent)
221 bpf_rcu_read_unlock();
222 out:
223 return 0;
224 }
225
226 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
inproper_sleepable_helper(void * ctx)227 int inproper_sleepable_helper(void *ctx)
228 {
229 struct task_struct *task, *real_parent;
230 struct pt_regs *regs;
231 __u32 value = 0;
232 void *ptr;
233
234 task = bpf_get_current_task_btf();
235 /* sleepable helper in rcu read lock region */
236 bpf_rcu_read_lock();
237 real_parent = task->real_parent;
238 if (!real_parent)
239 goto out;
240 regs = (struct pt_regs *)bpf_task_pt_regs(real_parent);
241 if (!regs)
242 goto out;
243
244 ptr = (void *)PT_REGS_IP(regs);
245 (void)bpf_copy_from_user_task(&value, sizeof(uint32_t), ptr, task, 0);
246 user_data = value;
247 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
248 out:
249 bpf_rcu_read_unlock();
250 return 0;
251 }
252
253 SEC("?lsm.s/bpf")
BPF_PROG(inproper_sleepable_kfunc,int cmd,union bpf_attr * attr,unsigned int size)254 int BPF_PROG(inproper_sleepable_kfunc, int cmd, union bpf_attr *attr, unsigned int size)
255 {
256 struct bpf_key *bkey;
257
258 /* sleepable kfunc in rcu read lock region */
259 bpf_rcu_read_lock();
260 bkey = bpf_lookup_user_key(key_serial, flags);
261 bpf_rcu_read_unlock();
262 if (!bkey)
263 return -1;
264 bpf_key_put(bkey);
265
266 return 0;
267 }
268
269 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
nested_rcu_region(void * ctx)270 int nested_rcu_region(void *ctx)
271 {
272 struct task_struct *task, *real_parent;
273
274 /* nested rcu read lock regions */
275 task = bpf_get_current_task_btf();
276 bpf_rcu_read_lock();
277 bpf_rcu_read_lock();
278 real_parent = task->real_parent;
279 if (!real_parent)
280 goto out;
281 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
282 out:
283 bpf_rcu_read_unlock();
284 bpf_rcu_read_unlock();
285 return 0;
286 }
287
288 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
task_untrusted_non_rcuptr(void * ctx)289 int task_untrusted_non_rcuptr(void *ctx)
290 {
291 struct task_struct *task, *group_leader;
292
293 task = bpf_get_current_task_btf();
294 bpf_rcu_read_lock();
295 /* the pointer group_leader marked as untrusted */
296 group_leader = task->real_parent->group_leader;
297 (void)bpf_task_storage_get(&map_a, group_leader, 0, 0);
298 bpf_rcu_read_unlock();
299 return 0;
300 }
301
302 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
task_untrusted_rcuptr(void * ctx)303 int task_untrusted_rcuptr(void *ctx)
304 {
305 struct task_struct *task, *real_parent;
306
307 task = bpf_get_current_task_btf();
308 bpf_rcu_read_lock();
309 real_parent = task->real_parent;
310 bpf_rcu_read_unlock();
311 /* helper use of rcu ptr outside the rcu read lock region */
312 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
313 return 0;
314 }
315
316 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
cross_rcu_region(void * ctx)317 int cross_rcu_region(void *ctx)
318 {
319 struct task_struct *task, *real_parent;
320
321 /* rcu ptr define/use in different regions */
322 task = bpf_get_current_task_btf();
323 bpf_rcu_read_lock();
324 real_parent = task->real_parent;
325 bpf_rcu_read_unlock();
326 bpf_rcu_read_lock();
327 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
328 bpf_rcu_read_unlock();
329 return 0;
330 }
331