summaryrefslogtreecommitdiff
path: root/lib/livepatch/test_klp_shadow_vars.c
blob: b991164908587e4f1ae3e59fc6599d0f9ad3e96c (plain)
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
// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com>

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/livepatch.h>
#include <linux/slab.h>

/*
 * Keep a small list of pointers so that we can print address-agnostic
 * pointer values.  Use a rolling integer count to differentiate the values.
 * Ironically we could have used the shadow variable API to do this, but
 * let's not lean too heavily on the very code we're testing.
 */
static LIST_HEAD(ptr_list);
struct shadow_ptr {
	void *ptr;
	int id;
	struct list_head list;
};

static void free_ptr_list(void)
{
	struct shadow_ptr *sp, *tmp_sp;

	list_for_each_entry_safe(sp, tmp_sp, &ptr_list, list) {
		list_del(&sp->list);
		kfree(sp);
	}
}

static int ptr_id(void *ptr)
{
	struct shadow_ptr *sp;
	static int count;

	list_for_each_entry(sp, &ptr_list, list) {
		if (sp->ptr == ptr)
			return sp->id;
	}

	sp = kmalloc(sizeof(*sp), GFP_ATOMIC);
	if (!sp)
		return -ENOMEM;
	sp->ptr = ptr;
	sp->id = count++;

	list_add(&sp->list, &ptr_list);

	return sp->id;
}

/*
 * Shadow variable wrapper functions that echo the function and arguments
 * to the kernel log for testing verification.  Don't display raw pointers,
 * but use the ptr_id() value instead.
 */
static void *shadow_get(void *obj, unsigned long id)
{
	int **sv;

	sv = klp_shadow_get(obj, id);
	pr_info("klp_%s(obj=PTR%d, id=0x%lx) = PTR%d\n",
		__func__, ptr_id(obj), id, ptr_id(sv));

	return sv;
}

static void *shadow_alloc(void *obj, unsigned long id, size_t size,
			  gfp_t gfp_flags, klp_shadow_ctor_t ctor,
			  void *ctor_data)
{
	int **var = ctor_data;
	int **sv;

	sv = klp_shadow_alloc(obj, id, size, gfp_flags, ctor, var);
	pr_info("klp_%s(obj=PTR%d, id=0x%lx, size=%zx, gfp_flags=%pGg), ctor=PTR%d, ctor_data=PTR%d = PTR%d\n",
		__func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
		ptr_id(*var), ptr_id(sv));

	return sv;
}

static void *shadow_get_or_alloc(void *obj, unsigned long id, size_t size,
				 gfp_t gfp_flags, klp_shadow_ctor_t ctor,
				 void *ctor_data)
{
	int **var = ctor_data;
	int **sv;

	sv = klp_shadow_get_or_alloc(obj, id, size, gfp_flags, ctor, var);
	pr_info("klp_%s(obj=PTR%d, id=0x%lx, size=%zx, gfp_flags=%pGg), ctor=PTR%d, ctor_data=PTR%d = PTR%d\n",
		__func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
		ptr_id(*var), ptr_id(sv));

	return sv;
}

static void shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor)
{
	klp_shadow_free(obj, id, dtor);
	pr_info("klp_%s(obj=PTR%d, id=0x%lx, dtor=PTR%d)\n",
		__func__, ptr_id(obj), id, ptr_id(dtor));
}

static void shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor)
{
	klp_shadow_free_all(id, dtor);
	pr_info("klp_%s(id=0x%lx, dtor=PTR%d)\n", __func__, id, ptr_id(dtor));
}


/* Shadow variable constructor - remember simple pointer data */
static int shadow_ctor(void *obj, void *shadow_data, void *ctor_data)
{
	int **sv = shadow_data;
	int **var = ctor_data;

	if (!var)
		return -EINVAL;

	*sv = *var;
	pr_info("%s: PTR%d -> PTR%d\n", __func__, ptr_id(sv), ptr_id(*var));

	return 0;
}

/*
 * With more than one item to free in the list, order is not determined and
 * shadow_dtor will not be passed to shadow_free_all() which would make the
 * test fail. (see pass 6)
 */
static void shadow_dtor(void *obj, void *shadow_data)
{
	int **sv = shadow_data;

	pr_info("%s(obj=PTR%d, shadow_data=PTR%d)\n",
		__func__, ptr_id(obj), ptr_id(sv));
}

/* number of objects we simulate that need shadow vars */
#define NUM_OBJS 3

/* dynamically created obj fields have the following shadow var id values */
#define SV_ID1 0x1234
#define SV_ID2 0x1235

/*
 * The main test case adds/removes new fields (shadow var) to each of these
 * test structure instances. The last group of fields in the struct represent
 * the idea that shadow variables may be added and removed to and from the
 * struct during execution.
 */
struct test_object {
	 /* add anything here below and avoid to define an empty struct */
	struct shadow_ptr sp;

	/* these represent shadow vars added and removed with SV_ID{1,2} */
	/* char nfield1; */
	/* int  nfield2; */
};

static int test_klp_shadow_vars_init(void)
{
	struct test_object objs[NUM_OBJS];
	char nfields1[NUM_OBJS], *pnfields1[NUM_OBJS], **sv1[NUM_OBJS];
	char *pndup[NUM_OBJS];
	int nfields2[NUM_OBJS], *pnfields2[NUM_OBJS], **sv2[NUM_OBJS];
	void **sv;
	int ret;
	int i;

	ptr_id(NULL);

	/*
	 * With an empty shadow variable hash table, expect not to find
	 * any matches.
	 */
	sv = shadow_get(&objs[0], SV_ID1);
	if (!sv)
		pr_info("  got expected NULL result\n");

	/* pass 1: init & alloc a char+int pair of svars for each objs */
	for (i = 0; i < NUM_OBJS; i++) {
		pnfields1[i] = &nfields1[i];
		ptr_id(pnfields1[i]);

		if (i % 2) {
			sv1[i] = shadow_alloc(&objs[i], SV_ID1,
					sizeof(pnfields1[i]), GFP_KERNEL,
					shadow_ctor, &pnfields1[i]);
		} else {
			sv1[i] = shadow_get_or_alloc(&objs[i], SV_ID1,
					sizeof(pnfields1[i]), GFP_KERNEL,
					shadow_ctor, &pnfields1[i]);
		}
		if (!sv1[i]) {
			ret = -ENOMEM;
			goto out;
		}

		pnfields2[i] = &nfields2[i];
		ptr_id(pnfields2[i]);
		sv2[i] = shadow_alloc(&objs[i], SV_ID2, sizeof(pnfields2[i]),
					GFP_KERNEL, shadow_ctor, &pnfields2[i]);
		if (!sv2[i]) {
			ret = -ENOMEM;
			goto out;
		}
	}

	/* pass 2: verify we find allocated svars and where they point to */
	for (i = 0; i < NUM_OBJS; i++) {
		/* check the "char" svar for all objects */
		sv = shadow_get(&objs[i], SV_ID1);
		if (!sv) {
			ret = -EINVAL;
			goto out;
		}
		if ((char **)sv == sv1[i] && *sv1[i] == pnfields1[i])
			pr_info("  got expected PTR%d -> PTR%d result\n",
				ptr_id(sv1[i]), ptr_id(*sv1[i]));

		/* check the "int" svar for all objects */
		sv = shadow_get(&objs[i], SV_ID2);
		if (!sv) {
			ret = -EINVAL;
			goto out;
		}
		if ((int **)sv == sv2[i] && *sv2[i] == pnfields2[i])
			pr_info("  got expected PTR%d -> PTR%d result\n",
				ptr_id(sv2[i]), ptr_id(*sv2[i]));
	}

	/* pass 3: verify that 'get_or_alloc' returns already allocated svars */
	for (i = 0; i < NUM_OBJS; i++) {
		pndup[i] = &nfields1[i];
		ptr_id(pndup[i]);

		sv = shadow_get_or_alloc(&objs[i], SV_ID1, sizeof(pndup[i]),
					GFP_KERNEL, shadow_ctor, &pndup[i]);
		if (!sv) {
			ret = -EINVAL;
			goto out;
		}
		if ((char **)sv == sv1[i] && *sv1[i] == pnfields1[i])
			pr_info("  got expected PTR%d -> PTR%d result\n",
					ptr_id(sv1[i]), ptr_id(*sv1[i]));
	}

	/* pass 4: free <objs[*], SV_ID1> pairs of svars, verify removal */
	for (i = 0; i < NUM_OBJS; i++) {
		shadow_free(&objs[i], SV_ID1, shadow_dtor); /* 'char' pairs */
		sv = shadow_get(&objs[i], SV_ID1);
		if (!sv)
			pr_info("  got expected NULL result\n");
	}

	/* pass 5: check we still find <objs[*], SV_ID2> svar pairs */
	for (i = 0; i < NUM_OBJS; i++) {
		sv = shadow_get(&objs[i], SV_ID2);	/* 'int' pairs */
		if (!sv) {
			ret = -EINVAL;
			goto out;
		}
		if ((int **)sv == sv2[i] && *sv2[i] == pnfields2[i])
			pr_info("  got expected PTR%d -> PTR%d result\n",
					ptr_id(sv2[i]), ptr_id(*sv2[i]));
	}

	/* pass 6: free all the <objs[*], SV_ID2> svar pairs too. */
	shadow_free_all(SV_ID2, NULL);		/* 'int' pairs */
	for (i = 0; i < NUM_OBJS; i++) {
		sv = shadow_get(&objs[i], SV_ID2);
		if (!sv)
			pr_info("  got expected NULL result\n");
	}

	free_ptr_list();

	return 0;
out:
	shadow_free_all(SV_ID1, NULL);		/* 'char' pairs */
	shadow_free_all(SV_ID2, NULL);		/* 'int' pairs */
	free_ptr_list();

	return ret;
}

static void test_klp_shadow_vars_exit(void)
{
}

module_init(test_klp_shadow_vars_init);
module_exit(test_klp_shadow_vars_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
MODULE_DESCRIPTION("Livepatch test: shadow variables");