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(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 	/* old style ptr_to_btf_id is not allowed in sleepable */
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(gparent);
163 	if (!gparent)
164 		goto out;
165 
166 	(void)bpf_task_storage_get(&map_a, gparent, 0, 0);
167 	bpf_task_release(gparent);
168 out:
169 	bpf_rcu_read_unlock();
170 	return 0;
171 }
172 
173 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
miss_lock(void * ctx)174 int miss_lock(void *ctx)
175 {
176 	struct task_struct *task;
177 
178 	/* missing bpf_rcu_read_lock() */
179 	task = bpf_get_current_task_btf();
180 	bpf_rcu_read_lock();
181 	(void)bpf_task_storage_get(&map_a, task, 0, 0);
182 	bpf_rcu_read_unlock();
183 	bpf_rcu_read_unlock();
184 	return 0;
185 }
186 
187 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
miss_unlock(void * ctx)188 int miss_unlock(void *ctx)
189 {
190 	struct task_struct *task;
191 
192 	/* missing bpf_rcu_read_unlock() */
193 	task = bpf_get_current_task_btf();
194 	bpf_rcu_read_lock();
195 	(void)bpf_task_storage_get(&map_a, task, 0, 0);
196 	return 0;
197 }
198 
199 SEC("?fentry/" SYS_PREFIX "sys_getpgid")
non_sleepable_rcu_mismatch(void * ctx)200 int non_sleepable_rcu_mismatch(void *ctx)
201 {
202 	struct task_struct *task, *real_parent;
203 
204 	task = bpf_get_current_task_btf();
205 	/* non-sleepable: missing bpf_rcu_read_unlock() in one path */
206 	bpf_rcu_read_lock();
207 	real_parent = task->real_parent;
208 	if (!real_parent)
209 		goto out;
210 	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
211 	if (real_parent)
212 		bpf_rcu_read_unlock();
213 out:
214 	return 0;
215 }
216 
217 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
inproper_sleepable_helper(void * ctx)218 int inproper_sleepable_helper(void *ctx)
219 {
220 	struct task_struct *task, *real_parent;
221 	struct pt_regs *regs;
222 	__u32 value = 0;
223 	void *ptr;
224 
225 	task = bpf_get_current_task_btf();
226 	/* sleepable helper in rcu read lock region */
227 	bpf_rcu_read_lock();
228 	real_parent = task->real_parent;
229 	if (!real_parent)
230 		goto out;
231 	regs = (struct pt_regs *)bpf_task_pt_regs(real_parent);
232 	if (!regs)
233 		goto out;
234 
235 	ptr = (void *)PT_REGS_IP(regs);
236 	(void)bpf_copy_from_user_task(&value, sizeof(uint32_t), ptr, task, 0);
237 	user_data = value;
238 	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
239 out:
240 	bpf_rcu_read_unlock();
241 	return 0;
242 }
243 
244 SEC("?lsm.s/bpf")
BPF_PROG(inproper_sleepable_kfunc,int cmd,union bpf_attr * attr,unsigned int size)245 int BPF_PROG(inproper_sleepable_kfunc, int cmd, union bpf_attr *attr, unsigned int size)
246 {
247 	struct bpf_key *bkey;
248 
249 	/* sleepable kfunc in rcu read lock region */
250 	bpf_rcu_read_lock();
251 	bkey = bpf_lookup_user_key(key_serial, flags);
252 	bpf_rcu_read_unlock();
253 	if (!bkey)
254 		return -1;
255 	bpf_key_put(bkey);
256 
257 	return 0;
258 }
259 
260 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
nested_rcu_region(void * ctx)261 int nested_rcu_region(void *ctx)
262 {
263 	struct task_struct *task, *real_parent;
264 
265 	/* nested rcu read lock regions */
266 	task = bpf_get_current_task_btf();
267 	bpf_rcu_read_lock();
268 	bpf_rcu_read_lock();
269 	real_parent = task->real_parent;
270 	if (!real_parent)
271 		goto out;
272 	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
273 out:
274 	bpf_rcu_read_unlock();
275 	bpf_rcu_read_unlock();
276 	return 0;
277 }
278 
279 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
task_trusted_non_rcuptr(void * ctx)280 int task_trusted_non_rcuptr(void *ctx)
281 {
282 	struct task_struct *task, *group_leader;
283 
284 	task = bpf_get_current_task_btf();
285 	bpf_rcu_read_lock();
286 	/* the pointer group_leader is explicitly marked as trusted */
287 	group_leader = task->real_parent->group_leader;
288 	(void)bpf_task_storage_get(&map_a, group_leader, 0, 0);
289 	bpf_rcu_read_unlock();
290 	return 0;
291 }
292 
293 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
task_untrusted_rcuptr(void * ctx)294 int task_untrusted_rcuptr(void *ctx)
295 {
296 	struct task_struct *task, *real_parent;
297 
298 	task = bpf_get_current_task_btf();
299 	bpf_rcu_read_lock();
300 	real_parent = task->real_parent;
301 	bpf_rcu_read_unlock();
302 	/* helper use of rcu ptr outside the rcu read lock region */
303 	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
304 	return 0;
305 }
306 
307 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
cross_rcu_region(void * ctx)308 int cross_rcu_region(void *ctx)
309 {
310 	struct task_struct *task, *real_parent;
311 
312 	/* rcu ptr define/use in different regions */
313 	task = bpf_get_current_task_btf();
314 	bpf_rcu_read_lock();
315 	real_parent = task->real_parent;
316 	bpf_rcu_read_unlock();
317 	bpf_rcu_read_lock();
318 	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
319 	bpf_rcu_read_unlock();
320 	return 0;
321 }
322