1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
|
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include "bpf_tracing_net.h"
#include "bpf_misc.h"
char _license[] SEC("license") = "GPL";
struct {
__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
__uint(map_flags, BPF_F_NO_PREALLOC);
__type(key, int);
__type(value, long);
} map_a SEC(".maps");
__u32 user_data, key_serial, target_pid;
__u64 flags, task_storage_val, cgroup_id;
struct bpf_key *bpf_lookup_user_key(__u32 serial, __u64 flags) __ksym;
void bpf_key_put(struct bpf_key *key) __ksym;
void bpf_rcu_read_lock(void) __ksym;
void bpf_rcu_read_unlock(void) __ksym;
struct task_struct *bpf_task_acquire_not_zero(struct task_struct *p) __ksym;
void bpf_task_release(struct task_struct *p) __ksym;
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int get_cgroup_id(void *ctx)
{
struct task_struct *task;
struct css_set *cgroups;
task = bpf_get_current_task_btf();
if (task->pid != target_pid)
return 0;
/* simulate bpf_get_current_cgroup_id() helper */
bpf_rcu_read_lock();
cgroups = task->cgroups;
if (!cgroups)
goto unlock;
cgroup_id = cgroups->dfl_cgrp->kn->id;
unlock:
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int task_succ(void *ctx)
{
struct task_struct *task, *real_parent;
long init_val = 2;
long *ptr;
task = bpf_get_current_task_btf();
if (task->pid != target_pid)
return 0;
bpf_rcu_read_lock();
/* region including helper using rcu ptr real_parent */
real_parent = task->real_parent;
if (!real_parent)
goto out;
ptr = bpf_task_storage_get(&map_a, real_parent, &init_val,
BPF_LOCAL_STORAGE_GET_F_CREATE);
if (!ptr)
goto out;
ptr = bpf_task_storage_get(&map_a, real_parent, 0, 0);
if (!ptr)
goto out;
task_storage_val = *ptr;
out:
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int no_lock(void *ctx)
{
struct task_struct *task, *real_parent;
/* old style ptr_to_btf_id is not allowed in sleepable */
task = bpf_get_current_task_btf();
real_parent = task->real_parent;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int two_regions(void *ctx)
{
struct task_struct *task, *real_parent;
/* two regions */
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
bpf_rcu_read_unlock();
bpf_rcu_read_lock();
real_parent = task->real_parent;
if (!real_parent)
goto out;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry/" SYS_PREFIX "sys_getpgid")
int non_sleepable_1(void *ctx)
{
struct task_struct *task, *real_parent;
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
real_parent = task->real_parent;
if (!real_parent)
goto out;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry/" SYS_PREFIX "sys_getpgid")
int non_sleepable_2(void *ctx)
{
struct task_struct *task, *real_parent;
bpf_rcu_read_lock();
task = bpf_get_current_task_btf();
bpf_rcu_read_unlock();
bpf_rcu_read_lock();
real_parent = task->real_parent;
if (!real_parent)
goto out;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int task_acquire(void *ctx)
{
struct task_struct *task, *real_parent, *gparent;
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
real_parent = task->real_parent;
if (!real_parent)
goto out;
/* rcu_ptr->rcu_field */
gparent = real_parent->real_parent;
if (!gparent)
goto out;
/* acquire a reference which can be used outside rcu read lock region */
gparent = bpf_task_acquire_not_zero(gparent);
if (!gparent)
/* Until we resolve the issues with using task->rcu_users, we
* expect bpf_task_acquire_not_zero() to return a NULL task.
* See the comment at the definition of
* bpf_task_acquire_not_zero() for more details.
*/
goto out;
(void)bpf_task_storage_get(&map_a, gparent, 0, 0);
bpf_task_release(gparent);
out:
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int miss_lock(void *ctx)
{
struct task_struct *task;
struct css_set *cgroups;
struct cgroup *dfl_cgrp;
/* missing bpf_rcu_read_lock() */
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
(void)bpf_task_storage_get(&map_a, task, 0, 0);
bpf_rcu_read_unlock();
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int miss_unlock(void *ctx)
{
struct task_struct *task;
struct css_set *cgroups;
struct cgroup *dfl_cgrp;
/* missing bpf_rcu_read_unlock() */
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
(void)bpf_task_storage_get(&map_a, task, 0, 0);
return 0;
}
SEC("?fentry/" SYS_PREFIX "sys_getpgid")
int non_sleepable_rcu_mismatch(void *ctx)
{
struct task_struct *task, *real_parent;
task = bpf_get_current_task_btf();
/* non-sleepable: missing bpf_rcu_read_unlock() in one path */
bpf_rcu_read_lock();
real_parent = task->real_parent;
if (!real_parent)
goto out;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
if (real_parent)
bpf_rcu_read_unlock();
out:
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int inproper_sleepable_helper(void *ctx)
{
struct task_struct *task, *real_parent;
struct pt_regs *regs;
__u32 value = 0;
void *ptr;
task = bpf_get_current_task_btf();
/* sleepable helper in rcu read lock region */
bpf_rcu_read_lock();
real_parent = task->real_parent;
if (!real_parent)
goto out;
regs = (struct pt_regs *)bpf_task_pt_regs(real_parent);
if (!regs)
goto out;
ptr = (void *)PT_REGS_IP(regs);
(void)bpf_copy_from_user_task(&value, sizeof(uint32_t), ptr, task, 0);
user_data = value;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
bpf_rcu_read_unlock();
return 0;
}
SEC("?lsm.s/bpf")
int BPF_PROG(inproper_sleepable_kfunc, int cmd, union bpf_attr *attr, unsigned int size)
{
struct bpf_key *bkey;
/* sleepable kfunc in rcu read lock region */
bpf_rcu_read_lock();
bkey = bpf_lookup_user_key(key_serial, flags);
bpf_rcu_read_unlock();
if (!bkey)
return -1;
bpf_key_put(bkey);
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int nested_rcu_region(void *ctx)
{
struct task_struct *task, *real_parent;
/* nested rcu read lock regions */
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
bpf_rcu_read_lock();
real_parent = task->real_parent;
if (!real_parent)
goto out;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
bpf_rcu_read_unlock();
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int task_trusted_non_rcuptr(void *ctx)
{
struct task_struct *task, *group_leader;
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
/* the pointer group_leader is explicitly marked as trusted */
group_leader = task->real_parent->group_leader;
(void)bpf_task_storage_get(&map_a, group_leader, 0, 0);
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int task_untrusted_rcuptr(void *ctx)
{
struct task_struct *task, *real_parent;
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
real_parent = task->real_parent;
bpf_rcu_read_unlock();
/* helper use of rcu ptr outside the rcu read lock region */
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int cross_rcu_region(void *ctx)
{
struct task_struct *task, *real_parent;
/* rcu ptr define/use in different regions */
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
real_parent = task->real_parent;
bpf_rcu_read_unlock();
bpf_rcu_read_lock();
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
bpf_rcu_read_unlock();
return 0;
}
|
