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_tracing.h>
6 #include <bpf/bpf_helpers.h>
7
8 #include "task_kfunc_common.h"
9
10 char _license[] SEC("license") = "GPL";
11
12 int err, pid;
13
14 /* Prototype for all of the program trace events below:
15 *
16 * TRACE_EVENT(task_newtask,
17 * TP_PROTO(struct task_struct *p, u64 clone_flags)
18 */
19
20 struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym __weak;
21
22 struct task_struct *bpf_task_acquire___one(struct task_struct *task) __ksym __weak;
23 /* The two-param bpf_task_acquire doesn't exist */
24 struct task_struct *bpf_task_acquire___two(struct task_struct *p, void *ctx) __ksym __weak;
25 /* Incorrect type for first param */
26 struct task_struct *bpf_task_acquire___three(void *ctx) __ksym __weak;
27
28 void invalid_kfunc(void) __ksym __weak;
29 void bpf_testmod_test_mod_kfunc(int i) __ksym __weak;
30
is_test_kfunc_task(void)31 static bool is_test_kfunc_task(void)
32 {
33 int cur_pid = bpf_get_current_pid_tgid() >> 32;
34
35 return pid == cur_pid;
36 }
37
test_acquire_release(struct task_struct * task)38 static int test_acquire_release(struct task_struct *task)
39 {
40 struct task_struct *acquired = NULL;
41
42 if (!bpf_ksym_exists(bpf_task_acquire)) {
43 err = 3;
44 return 0;
45 }
46 if (!bpf_ksym_exists(bpf_testmod_test_mod_kfunc)) {
47 err = 4;
48 return 0;
49 }
50 if (bpf_ksym_exists(invalid_kfunc)) {
51 /* the verifier's dead code elimination should remove this */
52 err = 5;
53 asm volatile ("goto -1"); /* for (;;); */
54 }
55
56 acquired = bpf_task_acquire(task);
57 if (acquired)
58 bpf_task_release(acquired);
59 else
60 err = 6;
61
62 return 0;
63 }
64
65 SEC("tp_btf/task_newtask")
BPF_PROG(test_task_kfunc_flavor_relo,struct task_struct * task,u64 clone_flags)66 int BPF_PROG(test_task_kfunc_flavor_relo, struct task_struct *task, u64 clone_flags)
67 {
68 struct task_struct *acquired = NULL;
69 int fake_ctx = 42;
70
71 if (bpf_ksym_exists(bpf_task_acquire___one)) {
72 acquired = bpf_task_acquire___one(task);
73 } else if (bpf_ksym_exists(bpf_task_acquire___two)) {
74 /* Here, bpf_object__resolve_ksym_func_btf_id's find_ksym_btf_id
75 * call will find vmlinux's bpf_task_acquire, but subsequent
76 * bpf_core_types_are_compat will fail
77 */
78 acquired = bpf_task_acquire___two(task, &fake_ctx);
79 err = 3;
80 return 0;
81 } else if (bpf_ksym_exists(bpf_task_acquire___three)) {
82 /* bpf_core_types_are_compat will fail similarly to above case */
83 acquired = bpf_task_acquire___three(&fake_ctx);
84 err = 4;
85 return 0;
86 }
87
88 if (acquired)
89 bpf_task_release(acquired);
90 else
91 err = 5;
92 return 0;
93 }
94
95 SEC("tp_btf/task_newtask")
BPF_PROG(test_task_kfunc_flavor_relo_not_found,struct task_struct * task,u64 clone_flags)96 int BPF_PROG(test_task_kfunc_flavor_relo_not_found, struct task_struct *task, u64 clone_flags)
97 {
98 /* Neither symbol should successfully resolve.
99 * Success or failure of one ___flavor should not affect others
100 */
101 if (bpf_ksym_exists(bpf_task_acquire___two))
102 err = 1;
103 else if (bpf_ksym_exists(bpf_task_acquire___three))
104 err = 2;
105
106 return 0;
107 }
108
109 SEC("tp_btf/task_newtask")
BPF_PROG(test_task_acquire_release_argument,struct task_struct * task,u64 clone_flags)110 int BPF_PROG(test_task_acquire_release_argument, struct task_struct *task, u64 clone_flags)
111 {
112 if (!is_test_kfunc_task())
113 return 0;
114
115 return test_acquire_release(task);
116 }
117
118 SEC("tp_btf/task_newtask")
BPF_PROG(test_task_acquire_release_current,struct task_struct * task,u64 clone_flags)119 int BPF_PROG(test_task_acquire_release_current, struct task_struct *task, u64 clone_flags)
120 {
121 if (!is_test_kfunc_task())
122 return 0;
123
124 return test_acquire_release(bpf_get_current_task_btf());
125 }
126
127 SEC("tp_btf/task_newtask")
BPF_PROG(test_task_acquire_leave_in_map,struct task_struct * task,u64 clone_flags)128 int BPF_PROG(test_task_acquire_leave_in_map, struct task_struct *task, u64 clone_flags)
129 {
130 long status;
131
132 if (!is_test_kfunc_task())
133 return 0;
134
135 status = tasks_kfunc_map_insert(task);
136 if (status)
137 err = 1;
138
139 return 0;
140 }
141
142 SEC("tp_btf/task_newtask")
BPF_PROG(test_task_xchg_release,struct task_struct * task,u64 clone_flags)143 int BPF_PROG(test_task_xchg_release, struct task_struct *task, u64 clone_flags)
144 {
145 struct task_struct *kptr;
146 struct __tasks_kfunc_map_value *v;
147 long status;
148
149 if (!is_test_kfunc_task())
150 return 0;
151
152 status = tasks_kfunc_map_insert(task);
153 if (status) {
154 err = 1;
155 return 0;
156 }
157
158 v = tasks_kfunc_map_value_lookup(task);
159 if (!v) {
160 err = 2;
161 return 0;
162 }
163
164 kptr = bpf_kptr_xchg(&v->task, NULL);
165 if (!kptr) {
166 err = 3;
167 return 0;
168 }
169
170 bpf_task_release(kptr);
171
172 return 0;
173 }
174
175 SEC("tp_btf/task_newtask")
BPF_PROG(test_task_map_acquire_release,struct task_struct * task,u64 clone_flags)176 int BPF_PROG(test_task_map_acquire_release, struct task_struct *task, u64 clone_flags)
177 {
178 struct task_struct *kptr;
179 struct __tasks_kfunc_map_value *v;
180 long status;
181
182 if (!is_test_kfunc_task())
183 return 0;
184
185 status = tasks_kfunc_map_insert(task);
186 if (status) {
187 err = 1;
188 return 0;
189 }
190
191 v = tasks_kfunc_map_value_lookup(task);
192 if (!v) {
193 err = 2;
194 return 0;
195 }
196
197 bpf_rcu_read_lock();
198 kptr = v->task;
199 if (!kptr) {
200 err = 3;
201 } else {
202 kptr = bpf_task_acquire(kptr);
203 if (!kptr)
204 err = 4;
205 else
206 bpf_task_release(kptr);
207 }
208 bpf_rcu_read_unlock();
209
210 return 0;
211 }
212
213 SEC("tp_btf/task_newtask")
BPF_PROG(test_task_current_acquire_release,struct task_struct * task,u64 clone_flags)214 int BPF_PROG(test_task_current_acquire_release, struct task_struct *task, u64 clone_flags)
215 {
216 struct task_struct *current, *acquired;
217
218 if (!is_test_kfunc_task())
219 return 0;
220
221 current = bpf_get_current_task_btf();
222 acquired = bpf_task_acquire(current);
223 if (acquired)
224 bpf_task_release(acquired);
225 else
226 err = 1;
227
228 return 0;
229 }
230
lookup_compare_pid(const struct task_struct * p)231 static void lookup_compare_pid(const struct task_struct *p)
232 {
233 struct task_struct *acquired;
234
235 acquired = bpf_task_from_pid(p->pid);
236 if (!acquired) {
237 err = 1;
238 return;
239 }
240
241 if (acquired->pid != p->pid)
242 err = 2;
243 bpf_task_release(acquired);
244 }
245
246 SEC("tp_btf/task_newtask")
BPF_PROG(test_task_from_pid_arg,struct task_struct * task,u64 clone_flags)247 int BPF_PROG(test_task_from_pid_arg, struct task_struct *task, u64 clone_flags)
248 {
249 if (!is_test_kfunc_task())
250 return 0;
251
252 lookup_compare_pid(task);
253 return 0;
254 }
255
256 SEC("tp_btf/task_newtask")
BPF_PROG(test_task_from_pid_current,struct task_struct * task,u64 clone_flags)257 int BPF_PROG(test_task_from_pid_current, struct task_struct *task, u64 clone_flags)
258 {
259 if (!is_test_kfunc_task())
260 return 0;
261
262 lookup_compare_pid(bpf_get_current_task_btf());
263 return 0;
264 }
265
is_pid_lookup_valid(s32 pid)266 static int is_pid_lookup_valid(s32 pid)
267 {
268 struct task_struct *acquired;
269
270 acquired = bpf_task_from_pid(pid);
271 if (acquired) {
272 bpf_task_release(acquired);
273 return 1;
274 }
275
276 return 0;
277 }
278
279 SEC("tp_btf/task_newtask")
BPF_PROG(test_task_from_pid_invalid,struct task_struct * task,u64 clone_flags)280 int BPF_PROG(test_task_from_pid_invalid, struct task_struct *task, u64 clone_flags)
281 {
282 if (!is_test_kfunc_task())
283 return 0;
284
285 bpf_strncmp(task->comm, 12, "foo");
286 bpf_strncmp(task->comm, 16, "foo");
287 bpf_strncmp(&task->comm[8], 4, "foo");
288
289 if (is_pid_lookup_valid(-1)) {
290 err = 1;
291 return 0;
292 }
293
294 if (is_pid_lookup_valid(0xcafef00d)) {
295 err = 2;
296 return 0;
297 }
298
299 return 0;
300 }
301
302 SEC("tp_btf/task_newtask")
BPF_PROG(task_kfunc_acquire_trusted_walked,struct task_struct * task,u64 clone_flags)303 int BPF_PROG(task_kfunc_acquire_trusted_walked, struct task_struct *task, u64 clone_flags)
304 {
305 struct task_struct *acquired;
306
307 /* task->group_leader is listed as a trusted, non-NULL field of task struct. */
308 acquired = bpf_task_acquire(task->group_leader);
309 if (acquired)
310 bpf_task_release(acquired);
311 else
312 err = 1;
313
314
315 return 0;
316 }
317