1 // SPDX-License-Identifier: GPL-2.0 1 // SPDX-License-Identifier: GPL-2.0
2 /* 2 /*
3 * fail_function.c: Function-based error injec 3 * fail_function.c: Function-based error injection
4 */ 4 */
5 #include <linux/error-injection.h> 5 #include <linux/error-injection.h>
6 #include <linux/debugfs.h> 6 #include <linux/debugfs.h>
7 #include <linux/fault-inject.h> 7 #include <linux/fault-inject.h>
8 #include <linux/kallsyms.h> 8 #include <linux/kallsyms.h>
9 #include <linux/kprobes.h> 9 #include <linux/kprobes.h>
10 #include <linux/module.h> 10 #include <linux/module.h>
11 #include <linux/mutex.h> 11 #include <linux/mutex.h>
12 #include <linux/slab.h> 12 #include <linux/slab.h>
13 #include <linux/uaccess.h> 13 #include <linux/uaccess.h>
14 14
15 static int fei_kprobe_handler(struct kprobe *k 15 static int fei_kprobe_handler(struct kprobe *kp, struct pt_regs *regs);
16 16
17 static void fei_post_handler(struct kprobe *kp 17 static void fei_post_handler(struct kprobe *kp, struct pt_regs *regs,
18 unsigned long fla 18 unsigned long flags)
19 { 19 {
20 /* 20 /*
21 * A dummy post handler is required to 21 * A dummy post handler is required to prohibit optimizing, because
22 * jump optimization does not support 22 * jump optimization does not support execution path overriding.
23 */ 23 */
24 } 24 }
25 25
26 struct fei_attr { 26 struct fei_attr {
27 struct list_head list; 27 struct list_head list;
28 struct kprobe kp; 28 struct kprobe kp;
29 unsigned long retval; 29 unsigned long retval;
30 }; 30 };
31 static DEFINE_MUTEX(fei_lock); 31 static DEFINE_MUTEX(fei_lock);
32 static LIST_HEAD(fei_attr_list); 32 static LIST_HEAD(fei_attr_list);
33 static DECLARE_FAULT_ATTR(fei_fault_attr); 33 static DECLARE_FAULT_ATTR(fei_fault_attr);
34 static struct dentry *fei_debugfs_dir; 34 static struct dentry *fei_debugfs_dir;
35 35
36 static unsigned long adjust_error_retval(unsig 36 static unsigned long adjust_error_retval(unsigned long addr, unsigned long retv)
37 { 37 {
38 switch (get_injectable_error_type(addr 38 switch (get_injectable_error_type(addr)) {
39 case EI_ETYPE_NULL: 39 case EI_ETYPE_NULL:
40 return 0; !! 40 if (retv != 0)
>> 41 return 0;
>> 42 break;
41 case EI_ETYPE_ERRNO: 43 case EI_ETYPE_ERRNO:
42 if (retv < (unsigned long)-MAX 44 if (retv < (unsigned long)-MAX_ERRNO)
43 return (unsigned long) 45 return (unsigned long)-EINVAL;
44 break; 46 break;
45 case EI_ETYPE_ERRNO_NULL: 47 case EI_ETYPE_ERRNO_NULL:
46 if (retv != 0 && retv < (unsig 48 if (retv != 0 && retv < (unsigned long)-MAX_ERRNO)
47 return (unsigned long) 49 return (unsigned long)-EINVAL;
48 break; 50 break;
49 case EI_ETYPE_TRUE: <<
50 return 1; <<
51 } 51 }
52 52
53 return retv; 53 return retv;
54 } 54 }
55 55
56 static struct fei_attr *fei_attr_new(const cha 56 static struct fei_attr *fei_attr_new(const char *sym, unsigned long addr)
57 { 57 {
58 struct fei_attr *attr; 58 struct fei_attr *attr;
59 59
60 attr = kzalloc(sizeof(*attr), GFP_KERN 60 attr = kzalloc(sizeof(*attr), GFP_KERNEL);
61 if (attr) { 61 if (attr) {
62 attr->kp.symbol_name = kstrdup 62 attr->kp.symbol_name = kstrdup(sym, GFP_KERNEL);
63 if (!attr->kp.symbol_name) { 63 if (!attr->kp.symbol_name) {
64 kfree(attr); 64 kfree(attr);
65 return NULL; 65 return NULL;
66 } 66 }
67 attr->kp.pre_handler = fei_kpr 67 attr->kp.pre_handler = fei_kprobe_handler;
68 attr->kp.post_handler = fei_po 68 attr->kp.post_handler = fei_post_handler;
69 attr->retval = adjust_error_re 69 attr->retval = adjust_error_retval(addr, 0);
70 INIT_LIST_HEAD(&attr->list); 70 INIT_LIST_HEAD(&attr->list);
71 } 71 }
72 return attr; 72 return attr;
73 } 73 }
74 74
75 static void fei_attr_free(struct fei_attr *att 75 static void fei_attr_free(struct fei_attr *attr)
76 { 76 {
77 if (attr) { 77 if (attr) {
78 kfree(attr->kp.symbol_name); 78 kfree(attr->kp.symbol_name);
79 kfree(attr); 79 kfree(attr);
80 } 80 }
81 } 81 }
82 82
83 static struct fei_attr *fei_attr_lookup(const 83 static struct fei_attr *fei_attr_lookup(const char *sym)
84 { 84 {
85 struct fei_attr *attr; 85 struct fei_attr *attr;
86 86
87 list_for_each_entry(attr, &fei_attr_li 87 list_for_each_entry(attr, &fei_attr_list, list) {
88 if (!strcmp(attr->kp.symbol_na 88 if (!strcmp(attr->kp.symbol_name, sym))
89 return attr; 89 return attr;
90 } 90 }
91 91
92 return NULL; 92 return NULL;
93 } 93 }
94 94
95 static bool fei_attr_is_valid(struct fei_attr 95 static bool fei_attr_is_valid(struct fei_attr *_attr)
96 { 96 {
97 struct fei_attr *attr; 97 struct fei_attr *attr;
98 98
99 list_for_each_entry(attr, &fei_attr_li 99 list_for_each_entry(attr, &fei_attr_list, list) {
100 if (attr == _attr) 100 if (attr == _attr)
101 return true; 101 return true;
102 } 102 }
103 103
104 return false; 104 return false;
105 } 105 }
106 106
107 static int fei_retval_set(void *data, u64 val) 107 static int fei_retval_set(void *data, u64 val)
108 { 108 {
109 struct fei_attr *attr = data; 109 struct fei_attr *attr = data;
110 unsigned long retv = (unsigned long)va 110 unsigned long retv = (unsigned long)val;
111 int err = 0; 111 int err = 0;
112 112
113 mutex_lock(&fei_lock); 113 mutex_lock(&fei_lock);
114 /* 114 /*
115 * Since this operation can be done af 115 * Since this operation can be done after retval file is removed,
116 * It is safer to check the attr is st 116 * It is safer to check the attr is still valid before accessing
117 * its member. 117 * its member.
118 */ 118 */
119 if (!fei_attr_is_valid(attr)) { 119 if (!fei_attr_is_valid(attr)) {
120 err = -ENOENT; 120 err = -ENOENT;
121 goto out; 121 goto out;
122 } 122 }
123 123
124 if (attr->kp.addr) { 124 if (attr->kp.addr) {
125 if (adjust_error_retval((unsig 125 if (adjust_error_retval((unsigned long)attr->kp.addr,
126 val) ! 126 val) != retv)
127 err = -EINVAL; 127 err = -EINVAL;
128 } 128 }
129 if (!err) 129 if (!err)
130 attr->retval = val; 130 attr->retval = val;
131 out: 131 out:
132 mutex_unlock(&fei_lock); 132 mutex_unlock(&fei_lock);
133 133
134 return err; 134 return err;
135 } 135 }
136 136
137 static int fei_retval_get(void *data, u64 *val 137 static int fei_retval_get(void *data, u64 *val)
138 { 138 {
139 struct fei_attr *attr = data; 139 struct fei_attr *attr = data;
140 int err = 0; 140 int err = 0;
141 141
142 mutex_lock(&fei_lock); 142 mutex_lock(&fei_lock);
143 /* Here we also validate @attr to ensu 143 /* Here we also validate @attr to ensure it still exists. */
144 if (!fei_attr_is_valid(attr)) 144 if (!fei_attr_is_valid(attr))
145 err = -ENOENT; 145 err = -ENOENT;
146 else 146 else
147 *val = attr->retval; 147 *val = attr->retval;
148 mutex_unlock(&fei_lock); 148 mutex_unlock(&fei_lock);
149 149
150 return err; 150 return err;
151 } 151 }
152 DEFINE_DEBUGFS_ATTRIBUTE(fei_retval_ops, fei_r 152 DEFINE_DEBUGFS_ATTRIBUTE(fei_retval_ops, fei_retval_get, fei_retval_set,
153 "%llx\n"); 153 "%llx\n");
154 154
155 static void fei_debugfs_add_attr(struct fei_at 155 static void fei_debugfs_add_attr(struct fei_attr *attr)
156 { 156 {
157 struct dentry *dir; 157 struct dentry *dir;
158 158
159 dir = debugfs_create_dir(attr->kp.symb 159 dir = debugfs_create_dir(attr->kp.symbol_name, fei_debugfs_dir);
160 160
161 debugfs_create_file("retval", 0600, di 161 debugfs_create_file("retval", 0600, dir, attr, &fei_retval_ops);
162 } 162 }
163 163
164 static void fei_debugfs_remove_attr(struct fei 164 static void fei_debugfs_remove_attr(struct fei_attr *attr)
165 { 165 {
166 debugfs_lookup_and_remove(attr->kp.sym !! 166 struct dentry *dir;
>> 167
>> 168 dir = debugfs_lookup(attr->kp.symbol_name, fei_debugfs_dir);
>> 169 debugfs_remove_recursive(dir);
167 } 170 }
168 171
169 static int fei_kprobe_handler(struct kprobe *k 172 static int fei_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)
170 { 173 {
171 struct fei_attr *attr = container_of(k 174 struct fei_attr *attr = container_of(kp, struct fei_attr, kp);
172 175
173 if (should_fail(&fei_fault_attr, 1)) { 176 if (should_fail(&fei_fault_attr, 1)) {
174 regs_set_return_value(regs, at 177 regs_set_return_value(regs, attr->retval);
175 override_function_with_return( 178 override_function_with_return(regs);
176 return 1; 179 return 1;
177 } 180 }
178 181
179 return 0; 182 return 0;
180 } 183 }
181 NOKPROBE_SYMBOL(fei_kprobe_handler) 184 NOKPROBE_SYMBOL(fei_kprobe_handler)
182 185
183 static void *fei_seq_start(struct seq_file *m, 186 static void *fei_seq_start(struct seq_file *m, loff_t *pos)
184 { 187 {
185 mutex_lock(&fei_lock); 188 mutex_lock(&fei_lock);
186 return seq_list_start(&fei_attr_list, 189 return seq_list_start(&fei_attr_list, *pos);
187 } 190 }
188 191
189 static void fei_seq_stop(struct seq_file *m, v 192 static void fei_seq_stop(struct seq_file *m, void *v)
190 { 193 {
191 mutex_unlock(&fei_lock); 194 mutex_unlock(&fei_lock);
192 } 195 }
193 196
194 static void *fei_seq_next(struct seq_file *m, 197 static void *fei_seq_next(struct seq_file *m, void *v, loff_t *pos)
195 { 198 {
196 return seq_list_next(v, &fei_attr_list 199 return seq_list_next(v, &fei_attr_list, pos);
197 } 200 }
198 201
199 static int fei_seq_show(struct seq_file *m, vo 202 static int fei_seq_show(struct seq_file *m, void *v)
200 { 203 {
201 struct fei_attr *attr = list_entry(v, 204 struct fei_attr *attr = list_entry(v, struct fei_attr, list);
202 205
203 seq_printf(m, "%ps\n", attr->kp.addr); 206 seq_printf(m, "%ps\n", attr->kp.addr);
204 return 0; 207 return 0;
205 } 208 }
206 209
207 static const struct seq_operations fei_seq_ops 210 static const struct seq_operations fei_seq_ops = {
208 .start = fei_seq_start, 211 .start = fei_seq_start,
209 .next = fei_seq_next, 212 .next = fei_seq_next,
210 .stop = fei_seq_stop, 213 .stop = fei_seq_stop,
211 .show = fei_seq_show, 214 .show = fei_seq_show,
212 }; 215 };
213 216
214 static int fei_open(struct inode *inode, struc 217 static int fei_open(struct inode *inode, struct file *file)
215 { 218 {
216 return seq_open(file, &fei_seq_ops); 219 return seq_open(file, &fei_seq_ops);
217 } 220 }
218 221
219 static void fei_attr_remove(struct fei_attr *a 222 static void fei_attr_remove(struct fei_attr *attr)
220 { 223 {
221 fei_debugfs_remove_attr(attr); 224 fei_debugfs_remove_attr(attr);
222 unregister_kprobe(&attr->kp); 225 unregister_kprobe(&attr->kp);
223 list_del(&attr->list); 226 list_del(&attr->list);
224 fei_attr_free(attr); 227 fei_attr_free(attr);
225 } 228 }
226 229
227 static void fei_attr_remove_all(void) 230 static void fei_attr_remove_all(void)
228 { 231 {
229 struct fei_attr *attr, *n; 232 struct fei_attr *attr, *n;
230 233
231 list_for_each_entry_safe(attr, n, &fei 234 list_for_each_entry_safe(attr, n, &fei_attr_list, list) {
232 fei_attr_remove(attr); 235 fei_attr_remove(attr);
233 } 236 }
234 } 237 }
235 238
236 static ssize_t fei_write(struct file *file, co 239 static ssize_t fei_write(struct file *file, const char __user *buffer,
237 size_t count, loff_t 240 size_t count, loff_t *ppos)
238 { 241 {
239 struct fei_attr *attr; 242 struct fei_attr *attr;
240 unsigned long addr; 243 unsigned long addr;
241 char *buf, *sym; 244 char *buf, *sym;
242 int ret; 245 int ret;
243 246
244 /* cut off if it is too long */ 247 /* cut off if it is too long */
245 if (count > KSYM_NAME_LEN) 248 if (count > KSYM_NAME_LEN)
246 count = KSYM_NAME_LEN; 249 count = KSYM_NAME_LEN;
>> 250 buf = kmalloc(count + 1, GFP_KERNEL);
>> 251 if (!buf)
>> 252 return -ENOMEM;
247 253
248 buf = memdup_user_nul(buffer, count); !! 254 if (copy_from_user(buf, buffer, count)) {
249 if (IS_ERR(buf)) !! 255 ret = -EFAULT;
250 return PTR_ERR(buf); !! 256 goto out;
251 !! 257 }
>> 258 buf[count] = '\0';
252 sym = strstrip(buf); 259 sym = strstrip(buf);
253 260
254 mutex_lock(&fei_lock); 261 mutex_lock(&fei_lock);
255 262
256 /* Writing just spaces will remove all 263 /* Writing just spaces will remove all injection points */
257 if (sym[0] == '\0') { 264 if (sym[0] == '\0') {
258 fei_attr_remove_all(); 265 fei_attr_remove_all();
259 ret = count; 266 ret = count;
260 goto out; 267 goto out;
261 } 268 }
262 /* Writing !function will remove one i 269 /* Writing !function will remove one injection point */
263 if (sym[0] == '!') { 270 if (sym[0] == '!') {
264 attr = fei_attr_lookup(sym + 1 271 attr = fei_attr_lookup(sym + 1);
265 if (!attr) { 272 if (!attr) {
266 ret = -ENOENT; 273 ret = -ENOENT;
267 goto out; 274 goto out;
268 } 275 }
269 fei_attr_remove(attr); 276 fei_attr_remove(attr);
270 ret = count; 277 ret = count;
271 goto out; 278 goto out;
272 } 279 }
273 280
274 addr = kallsyms_lookup_name(sym); 281 addr = kallsyms_lookup_name(sym);
275 if (!addr) { 282 if (!addr) {
276 ret = -EINVAL; 283 ret = -EINVAL;
277 goto out; 284 goto out;
278 } 285 }
279 if (!within_error_injection_list(addr) 286 if (!within_error_injection_list(addr)) {
280 ret = -ERANGE; 287 ret = -ERANGE;
281 goto out; 288 goto out;
282 } 289 }
283 if (fei_attr_lookup(sym)) { 290 if (fei_attr_lookup(sym)) {
284 ret = -EBUSY; 291 ret = -EBUSY;
285 goto out; 292 goto out;
286 } 293 }
287 attr = fei_attr_new(sym, addr); 294 attr = fei_attr_new(sym, addr);
288 if (!attr) { 295 if (!attr) {
289 ret = -ENOMEM; 296 ret = -ENOMEM;
290 goto out; 297 goto out;
291 } 298 }
292 299
293 ret = register_kprobe(&attr->kp); 300 ret = register_kprobe(&attr->kp);
294 if (ret) { !! 301 if (!ret)
295 fei_attr_free(attr); !! 302 fei_debugfs_add_attr(attr);
296 goto out; !! 303 if (ret < 0)
>> 304 fei_attr_remove(attr);
>> 305 else {
>> 306 list_add_tail(&attr->list, &fei_attr_list);
>> 307 ret = count;
297 } 308 }
298 fei_debugfs_add_attr(attr); <<
299 list_add_tail(&attr->list, &fei_attr_l <<
300 ret = count; <<
301 out: 309 out:
302 mutex_unlock(&fei_lock); <<
303 kfree(buf); 310 kfree(buf);
>> 311 mutex_unlock(&fei_lock);
304 return ret; 312 return ret;
305 } 313 }
306 314
307 static const struct file_operations fei_ops = 315 static const struct file_operations fei_ops = {
308 .open = fei_open, 316 .open = fei_open,
309 .read = seq_read, 317 .read = seq_read,
310 .write = fei_write, 318 .write = fei_write,
311 .llseek = seq_lseek, 319 .llseek = seq_lseek,
312 .release = seq_release, 320 .release = seq_release,
313 }; 321 };
314 322
315 static int __init fei_debugfs_init(void) 323 static int __init fei_debugfs_init(void)
316 { 324 {
317 struct dentry *dir; 325 struct dentry *dir;
318 326
319 dir = fault_create_debugfs_attr("fail_ 327 dir = fault_create_debugfs_attr("fail_function", NULL,
320 &fei_f 328 &fei_fault_attr);
321 if (IS_ERR(dir)) 329 if (IS_ERR(dir))
322 return PTR_ERR(dir); 330 return PTR_ERR(dir);
323 331
324 /* injectable attribute is just a syml 332 /* injectable attribute is just a symlink of error_inject/list */
325 debugfs_create_symlink("injectable", d 333 debugfs_create_symlink("injectable", dir, "../error_injection/list");
326 334
327 debugfs_create_file("inject", 0600, di 335 debugfs_create_file("inject", 0600, dir, NULL, &fei_ops);
328 336
329 fei_debugfs_dir = dir; 337 fei_debugfs_dir = dir;
330 338
331 return 0; 339 return 0;
332 } 340 }
333 341
334 late_initcall(fei_debugfs_init); 342 late_initcall(fei_debugfs_init);
335 343
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