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
|
// SPDX-License-Identifier: GPL-2.0
#include <vmlinux.h>
#include <bpf/bpf_tracing.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_core_read.h>
#include "bpf_experimental.h"
#include "bpf_misc.h"
struct node_data {
long key;
long data;
struct bpf_rb_node node;
};
#define private(name) SEC(".data." #name) __hidden __attribute__((aligned(8)))
private(A) struct bpf_spin_lock glock;
private(A) struct bpf_rb_root groot __contains(node_data, node);
private(A) struct bpf_rb_root groot2 __contains(node_data, node);
static bool less(struct bpf_rb_node *a, const struct bpf_rb_node *b)
{
struct node_data *node_a;
struct node_data *node_b;
node_a = container_of(a, struct node_data, node);
node_b = container_of(b, struct node_data, node);
return node_a->key < node_b->key;
}
SEC("?tc")
__failure __msg("bpf_spin_lock at off=16 must be held for bpf_rb_root")
long rbtree_api_nolock_add(void *ctx)
{
struct node_data *n;
n = bpf_obj_new(typeof(*n));
if (!n)
return 1;
bpf_rbtree_add(&groot, &n->node, less);
return 0;
}
SEC("?tc")
__failure __msg("bpf_spin_lock at off=16 must be held for bpf_rb_root")
long rbtree_api_nolock_remove(void *ctx)
{
struct node_data *n;
n = bpf_obj_new(typeof(*n));
if (!n)
return 1;
bpf_spin_lock(&glock);
bpf_rbtree_add(&groot, &n->node, less);
bpf_spin_unlock(&glock);
bpf_rbtree_remove(&groot, &n->node);
return 0;
}
SEC("?tc")
__failure __msg("bpf_spin_lock at off=16 must be held for bpf_rb_root")
long rbtree_api_nolock_first(void *ctx)
{
bpf_rbtree_first(&groot);
return 0;
}
SEC("?tc")
__failure __msg("rbtree_remove node input must be non-owning ref")
long rbtree_api_remove_unadded_node(void *ctx)
{
struct node_data *n, *m;
struct bpf_rb_node *res;
n = bpf_obj_new(typeof(*n));
if (!n)
return 1;
m = bpf_obj_new(typeof(*m));
if (!m) {
bpf_obj_drop(n);
return 1;
}
bpf_spin_lock(&glock);
bpf_rbtree_add(&groot, &n->node, less);
/* This remove should pass verifier */
res = bpf_rbtree_remove(&groot, &n->node);
n = container_of(res, struct node_data, node);
/* This remove shouldn't, m isn't in an rbtree */
res = bpf_rbtree_remove(&groot, &m->node);
m = container_of(res, struct node_data, node);
bpf_spin_unlock(&glock);
if (n)
bpf_obj_drop(n);
if (m)
bpf_obj_drop(m);
return 0;
}
SEC("?tc")
__failure __msg("Unreleased reference id=2 alloc_insn=11")
long rbtree_api_remove_no_drop(void *ctx)
{
struct bpf_rb_node *res;
struct node_data *n;
bpf_spin_lock(&glock);
res = bpf_rbtree_first(&groot);
if (!res)
goto unlock_err;
res = bpf_rbtree_remove(&groot, res);
n = container_of(res, struct node_data, node);
bpf_spin_unlock(&glock);
/* bpf_obj_drop(n) is missing here */
return 0;
unlock_err:
bpf_spin_unlock(&glock);
return 1;
}
SEC("?tc")
__failure __msg("arg#1 expected pointer to allocated object")
long rbtree_api_add_to_multiple_trees(void *ctx)
{
struct node_data *n;
n = bpf_obj_new(typeof(*n));
if (!n)
return 1;
bpf_spin_lock(&glock);
bpf_rbtree_add(&groot, &n->node, less);
/* This add should fail since n already in groot's tree */
bpf_rbtree_add(&groot2, &n->node, less);
bpf_spin_unlock(&glock);
return 0;
}
SEC("?tc")
__failure __msg("rbtree_remove node input must be non-owning ref")
long rbtree_api_add_release_unlock_escape(void *ctx)
{
struct node_data *n;
n = bpf_obj_new(typeof(*n));
if (!n)
return 1;
bpf_spin_lock(&glock);
bpf_rbtree_add(&groot, &n->node, less);
bpf_spin_unlock(&glock);
bpf_spin_lock(&glock);
/* After add() in previous critical section, n should be
* release_on_unlock and released after previous spin_unlock,
* so should not be possible to use it here
*/
bpf_rbtree_remove(&groot, &n->node);
bpf_spin_unlock(&glock);
return 0;
}
SEC("?tc")
__failure __msg("rbtree_remove node input must be non-owning ref")
long rbtree_api_release_aliasing(void *ctx)
{
struct node_data *n, *m, *o;
struct bpf_rb_node *res;
n = bpf_obj_new(typeof(*n));
if (!n)
return 1;
bpf_spin_lock(&glock);
bpf_rbtree_add(&groot, &n->node, less);
bpf_spin_unlock(&glock);
bpf_spin_lock(&glock);
/* m and o point to the same node,
* but verifier doesn't know this
*/
res = bpf_rbtree_first(&groot);
if (!res)
return 1;
o = container_of(res, struct node_data, node);
res = bpf_rbtree_first(&groot);
if (!res)
return 1;
m = container_of(res, struct node_data, node);
bpf_rbtree_remove(&groot, &m->node);
/* This second remove shouldn't be possible. Retval of previous
* remove returns owning reference to m, which is the same
* node o's non-owning ref is pointing at
*
* In order to preserve property
* * owning ref must not be in rbtree
* * non-owning ref must be in rbtree
*
* o's ref must be invalidated after previous remove. Otherwise
* we'd have non-owning ref to node that isn't in rbtree, and
* verifier wouldn't be able to use type system to prevent remove
* of ref that already isn't in any tree. Would have to do runtime
* checks in that case.
*/
bpf_rbtree_remove(&groot, &o->node);
bpf_spin_unlock(&glock);
return 0;
}
SEC("?tc")
__failure __msg("rbtree_remove node input must be non-owning ref")
long rbtree_api_first_release_unlock_escape(void *ctx)
{
struct bpf_rb_node *res;
struct node_data *n;
bpf_spin_lock(&glock);
res = bpf_rbtree_first(&groot);
if (res)
n = container_of(res, struct node_data, node);
bpf_spin_unlock(&glock);
bpf_spin_lock(&glock);
/* After first() in previous critical section, n should be
* release_on_unlock and released after previous spin_unlock,
* so should not be possible to use it here
*/
bpf_rbtree_remove(&groot, &n->node);
bpf_spin_unlock(&glock);
return 0;
}
static bool less__bad_fn_call_add(struct bpf_rb_node *a, const struct bpf_rb_node *b)
{
struct node_data *node_a;
struct node_data *node_b;
node_a = container_of(a, struct node_data, node);
node_b = container_of(b, struct node_data, node);
bpf_rbtree_add(&groot, &node_a->node, less);
return node_a->key < node_b->key;
}
static bool less__bad_fn_call_remove(struct bpf_rb_node *a, const struct bpf_rb_node *b)
{
struct node_data *node_a;
struct node_data *node_b;
node_a = container_of(a, struct node_data, node);
node_b = container_of(b, struct node_data, node);
bpf_rbtree_remove(&groot, &node_a->node);
return node_a->key < node_b->key;
}
static bool less__bad_fn_call_first_unlock_after(struct bpf_rb_node *a, const struct bpf_rb_node *b)
{
struct node_data *node_a;
struct node_data *node_b;
node_a = container_of(a, struct node_data, node);
node_b = container_of(b, struct node_data, node);
bpf_rbtree_first(&groot);
bpf_spin_unlock(&glock);
return node_a->key < node_b->key;
}
static __always_inline
long add_with_cb(bool (cb)(struct bpf_rb_node *a, const struct bpf_rb_node *b))
{
struct node_data *n;
n = bpf_obj_new(typeof(*n));
if (!n)
return 1;
bpf_spin_lock(&glock);
bpf_rbtree_add(&groot, &n->node, cb);
bpf_spin_unlock(&glock);
return 0;
}
SEC("?tc")
__failure __msg("arg#1 expected pointer to allocated object")
long rbtree_api_add_bad_cb_bad_fn_call_add(void *ctx)
{
return add_with_cb(less__bad_fn_call_add);
}
SEC("?tc")
__failure __msg("rbtree_remove not allowed in rbtree cb")
long rbtree_api_add_bad_cb_bad_fn_call_remove(void *ctx)
{
return add_with_cb(less__bad_fn_call_remove);
}
SEC("?tc")
__failure __msg("can't spin_{lock,unlock} in rbtree cb")
long rbtree_api_add_bad_cb_bad_fn_call_first_unlock_after(void *ctx)
{
return add_with_cb(less__bad_fn_call_first_unlock_after);
}
char _license[] SEC("license") = "GPL";
|
