kernel/sysctl-test.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * KUnit test of proc sysctl.
   4  */
   5
   6 #include <kunit/test.h>
   7 #include <linux/sysctl.h>
   8
   9 #define KUNIT_PROC_READ 0
  10 #define KUNIT_PROC_WRITE 1
  11
  12 static int i_zero;
  13 static int i_one_hundred = 100;
  14
  15 /*
  16  * Test that proc_dointvec will not try to use a NULL .data field even when the
  17  * length is non-zero.
  18  */
  19 static void sysctl_test_api_dointvec_null_tbl_data(struct kunit *test)
  20 {
  21         struct ctl_table null_data_table = {
  22                 .procname = "foo",
  23                 /*
  24                  * Here we are testing that proc_dointvec behaves correctly when
  25                  * we give it a NULL .data field. Normally this would point to a
  26                  * piece of memory where the value would be stored.
  27                  */
  28                 .data           = NULL,
  29                 .maxlen         = sizeof(int),
  30                 .mode           = 0644,
  31                 .proc_handler   = proc_dointvec,
  32                 .extra1         = &i_zero,
  33                 .extra2         = &i_one_hundred,
  34         };
  35         /*
  36          * proc_dointvec expects a buffer in user space, so we allocate one. We
  37          * also need to cast it to __user so sparse doesn't get mad.
  38          */
  39         void __user *buffer = (void __user *)kunit_kzalloc(test, sizeof(int),
  40                                                            GFP_USER);
  41         size_t len;
  42         loff_t pos;
  43
  44         /*
  45          * We don't care what the starting length is since proc_dointvec should
  46          * not try to read because .data is NULL.
  47          */
  48         len = 1234;
  49         KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&null_data_table,
  50                                                KUNIT_PROC_READ, buffer, &len,
  51                                                &pos));
  52         KUNIT_EXPECT_EQ(test, (size_t)0, len);
  53
  54         /*
  55          * See above.
  56          */
  57         len = 1234;
  58         KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&null_data_table,
  59                                                KUNIT_PROC_WRITE, buffer, &len,
  60                                                &pos));
  61         KUNIT_EXPECT_EQ(test, (size_t)0, len);
  62 }
  63
  64 /*
  65  * Similar to the previous test, we create a struct ctrl_table that has a .data
  66  * field that proc_dointvec cannot do anything with; however, this time it is
  67  * because we tell proc_dointvec that the size is 0.
  68  */
  69 static void sysctl_test_api_dointvec_table_maxlen_unset(struct kunit *test)
  70 {
  71         int data = 0;
  72         struct ctl_table data_maxlen_unset_table = {
  73                 .procname = "foo",
  74                 .data           = &data,
  75                 /*
  76                  * So .data is no longer NULL, but we tell proc_dointvec its
  77                  * length is 0, so it still shouldn't try to use it.
  78                  */
  79                 .maxlen         = 0,
  80                 .mode           = 0644,
  81                 .proc_handler   = proc_dointvec,
  82                 .extra1         = &i_zero,
  83                 .extra2         = &i_one_hundred,
  84         };
  85         void __user *buffer = (void __user *)kunit_kzalloc(test, sizeof(int),
  86                                                            GFP_USER);
  87         size_t len;
  88         loff_t pos;
  89
  90         /*
  91          * As before, we don't care what buffer length is because proc_dointvec
  92          * cannot do anything because its internal .data buffer has zero length.
  93          */
  94         len = 1234;
  95         KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&data_maxlen_unset_table,
  96                                                KUNIT_PROC_READ, buffer, &len,
  97                                                &pos));
  98         KUNIT_EXPECT_EQ(test, (size_t)0, len);
  99
 100         /*
 101          * See previous comment.
 102          */
 103         len = 1234;
 104         KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&data_maxlen_unset_table,
 105                                                KUNIT_PROC_WRITE, buffer, &len,
 106                                                &pos));
 107         KUNIT_EXPECT_EQ(test, (size_t)0, len);
 108 }
 109
 110 /*
 111  * Here we provide a valid struct ctl_table, but we try to read and write from
 112  * it using a buffer of zero length, so it should still fail in a similar way as
 113  * before.
 114  */
 115 static void sysctl_test_api_dointvec_table_len_is_zero(struct kunit *test)
 116 {
 117         int data = 0;
 118         /* Good table. */
 119         struct ctl_table table = {
 120                 .procname = "foo",
 121                 .data           = &data,
 122                 .maxlen         = sizeof(int),
 123                 .mode           = 0644,
 124                 .proc_handler   = proc_dointvec,
 125                 .extra1         = &i_zero,
 126                 .extra2         = &i_one_hundred,
 127         };
 128         void __user *buffer = (void __user *)kunit_kzalloc(test, sizeof(int),
 129                                                            GFP_USER);
 130         /*
 131          * However, now our read/write buffer has zero length.
 132          */
 133         size_t len = 0;
 134         loff_t pos;
 135
 136         KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, KUNIT_PROC_READ, buffer,
 137                                                &len, &pos));
 138         KUNIT_EXPECT_EQ(test, (size_t)0, len);
 139
 140         KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, KUNIT_PROC_WRITE, buffer,
 141                                                &len, &pos));
 142         KUNIT_EXPECT_EQ(test, (size_t)0, len);
 143 }
 144
 145 /*
 146  * Test that proc_dointvec refuses to read when the file position is non-zero.
 147  */
 148 static void sysctl_test_api_dointvec_table_read_but_position_set(
 149                 struct kunit *test)
 150 {
 151         int data = 0;
 152         /* Good table. */
 153         struct ctl_table table = {
 154                 .procname = "foo",
 155                 .data           = &data,
 156                 .maxlen         = sizeof(int),
 157                 .mode           = 0644,
 158                 .proc_handler   = proc_dointvec,
 159                 .extra1         = &i_zero,
 160                 .extra2         = &i_one_hundred,
 161         };
 162         void __user *buffer = (void __user *)kunit_kzalloc(test, sizeof(int),
 163                                                            GFP_USER);
 164         /*
 165          * We don't care about our buffer length because we start off with a
 166          * non-zero file position.
 167          */
 168         size_t len = 1234;
 169         /*
 170          * proc_dointvec should refuse to read into the buffer since the file
 171          * pos is non-zero.
 172          */
 173         loff_t pos = 1;
 174
 175         KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, KUNIT_PROC_READ, buffer,
 176                                                &len, &pos));
 177         KUNIT_EXPECT_EQ(test, (size_t)0, len);
 178 }
 179
 180 /*
 181  * Test that we can read a two digit number in a sufficiently size buffer.
 182  * Nothing fancy.
 183  */
 184 static void sysctl_test_dointvec_read_happy_single_positive(struct kunit *test)
 185 {
 186         int data = 0;
 187         /* Good table. */
 188         struct ctl_table table = {
 189                 .procname = "foo",
 190                 .data           = &data,
 191                 .maxlen         = sizeof(int),
 192                 .mode           = 0644,
 193                 .proc_handler   = proc_dointvec,
 194                 .extra1         = &i_zero,
 195                 .extra2         = &i_one_hundred,
 196         };
 197         size_t len = 4;
 198         loff_t pos = 0;
 199         char *buffer = kunit_kzalloc(test, len, GFP_USER);
 200         char __user *user_buffer = (char __user *)buffer;
 201         /* Store 13 in the data field. */
 202         *((int *)table.data) = 13;
 203
 204         KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, KUNIT_PROC_READ,
 205                                                user_buffer, &len, &pos));
 206         KUNIT_ASSERT_EQ(test, (size_t)3, len);
 207         buffer[len] = '\0';
 208         /* And we read 13 back out. */
 209         KUNIT_EXPECT_STREQ(test, "13\n", buffer);
 210 }
 211
 212 /*
 213  * Same as previous test, just now with negative numbers.
 214  */
 215 static void sysctl_test_dointvec_read_happy_single_negative(struct kunit *test)
 216 {
 217         int data = 0;
 218         /* Good table. */
 219         struct ctl_table table = {
 220                 .procname = "foo",
 221                 .data           = &data,
 222                 .maxlen         = sizeof(int),
 223                 .mode           = 0644,
 224                 .proc_handler   = proc_dointvec,
 225                 .extra1         = &i_zero,
 226                 .extra2         = &i_one_hundred,
 227         };
 228         size_t len = 5;
 229         loff_t pos = 0;
 230         char *buffer = kunit_kzalloc(test, len, GFP_USER);
 231         char __user *user_buffer = (char __user *)buffer;
 232         *((int *)table.data) = -16;
 233
 234         KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, KUNIT_PROC_READ,
 235                                                user_buffer, &len, &pos));
 236         KUNIT_ASSERT_EQ(test, (size_t)4, len);
 237         buffer[len] = '\0';
 238         KUNIT_EXPECT_STREQ(test, "-16\n", (char *)buffer);
 239 }
 240
 241 /*
 242  * Test that a simple positive write works.
 243  */
 244 static void sysctl_test_dointvec_write_happy_single_positive(struct kunit *test)
 245 {
 246         int data = 0;
 247         /* Good table. */
 248         struct ctl_table table = {
 249                 .procname = "foo",
 250                 .data           = &data,
 251                 .maxlen         = sizeof(int),
 252                 .mode           = 0644,
 253                 .proc_handler   = proc_dointvec,
 254                 .extra1         = &i_zero,
 255                 .extra2         = &i_one_hundred,
 256         };
 257         char input[] = "9";
 258         size_t len = sizeof(input) - 1;
 259         loff_t pos = 0;
 260         char *buffer = kunit_kzalloc(test, len, GFP_USER);
 261         char __user *user_buffer = (char __user *)buffer;
 262
 263         memcpy(buffer, input, len);
 264
 265         KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, KUNIT_PROC_WRITE,
 266                                                user_buffer, &len, &pos));
 267         KUNIT_EXPECT_EQ(test, sizeof(input) - 1, len);
 268         KUNIT_EXPECT_EQ(test, sizeof(input) - 1, (size_t)pos);
 269         KUNIT_EXPECT_EQ(test, 9, *((int *)table.data));
 270 }
 271
 272 /*
 273  * Same as previous test, but now with negative numbers.
 274  */
 275 static void sysctl_test_dointvec_write_happy_single_negative(struct kunit *test)
 276 {
 277         int data = 0;
 278         struct ctl_table table = {
 279                 .procname = "foo",
 280                 .data           = &data,
 281                 .maxlen         = sizeof(int),
 282                 .mode           = 0644,
 283                 .proc_handler   = proc_dointvec,
 284                 .extra1         = &i_zero,
 285                 .extra2         = &i_one_hundred,
 286         };
 287         char input[] = "-9";
 288         size_t len = sizeof(input) - 1;
 289         loff_t pos = 0;
 290         char *buffer = kunit_kzalloc(test, len, GFP_USER);
 291         char __user *user_buffer = (char __user *)buffer;
 292
 293         memcpy(buffer, input, len);
 294
 295         KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, KUNIT_PROC_WRITE,
 296                                                user_buffer, &len, &pos));
 297         KUNIT_EXPECT_EQ(test, sizeof(input) - 1, len);
 298         KUNIT_EXPECT_EQ(test, sizeof(input) - 1, (size_t)pos);
 299         KUNIT_EXPECT_EQ(test, -9, *((int *)table.data));
 300 }
 301
 302 /*
 303  * Test that writing a value smaller than the minimum possible value is not
 304  * allowed.
 305  */
 306 static void sysctl_test_api_dointvec_write_single_less_int_min(
 307                 struct kunit *test)
 308 {
 309         int data = 0;
 310         struct ctl_table table = {
 311                 .procname = "foo",
 312                 .data           = &data,
 313                 .maxlen         = sizeof(int),
 314                 .mode           = 0644,
 315                 .proc_handler   = proc_dointvec,
 316                 .extra1         = &i_zero,
 317                 .extra2         = &i_one_hundred,
 318         };
 319         size_t max_len = 32, len = max_len;
 320         loff_t pos = 0;
 321         char *buffer = kunit_kzalloc(test, max_len, GFP_USER);
 322         char __user *user_buffer = (char __user *)buffer;
 323         unsigned long abs_of_less_than_min = (unsigned long)INT_MAX
 324                                              - (INT_MAX + INT_MIN) + 1;
 325
 326         /*
 327          * We use this rigmarole to create a string that contains a value one
 328          * less than the minimum accepted value.
 329          */
 330         KUNIT_ASSERT_LT(test,
 331                         (size_t)snprintf(buffer, max_len, "-%lu",
 332                                          abs_of_less_than_min),
 333                         max_len);
 334
 335         KUNIT_EXPECT_EQ(test, -EINVAL, proc_dointvec(&table, KUNIT_PROC_WRITE,
 336                                                      user_buffer, &len, &pos));
 337         KUNIT_EXPECT_EQ(test, max_len, len);
 338         KUNIT_EXPECT_EQ(test, 0, *((int *)table.data));
 339 }
 340
 341 /*
 342  * Test that writing the maximum possible value works.
 343  */
 344 static void sysctl_test_api_dointvec_write_single_greater_int_max(
 345                 struct kunit *test)
 346 {
 347         int data = 0;
 348         struct ctl_table table = {
 349                 .procname = "foo",
 350                 .data           = &data,
 351                 .maxlen         = sizeof(int),
 352                 .mode           = 0644,
 353                 .proc_handler   = proc_dointvec,
 354                 .extra1         = &i_zero,
 355                 .extra2         = &i_one_hundred,
 356         };
 357         size_t max_len = 32, len = max_len;
 358         loff_t pos = 0;
 359         char *buffer = kunit_kzalloc(test, max_len, GFP_USER);
 360         char __user *user_buffer = (char __user *)buffer;
 361         unsigned long greater_than_max = (unsigned long)INT_MAX + 1;
 362
 363         KUNIT_ASSERT_GT(test, greater_than_max, (unsigned long)INT_MAX);
 364         KUNIT_ASSERT_LT(test, (size_t)snprintf(buffer, max_len, "%lu",
 365                                                greater_than_max),
 366                         max_len);
 367         KUNIT_EXPECT_EQ(test, -EINVAL, proc_dointvec(&table, KUNIT_PROC_WRITE,
 368                                                      user_buffer, &len, &pos));
 369         KUNIT_ASSERT_EQ(test, max_len, len);
 370         KUNIT_EXPECT_EQ(test, 0, *((int *)table.data));
 371 }
 372
 373 static struct kunit_case sysctl_test_cases[] = {
 374         KUNIT_CASE(sysctl_test_api_dointvec_null_tbl_data),
 375         KUNIT_CASE(sysctl_test_api_dointvec_table_maxlen_unset),
 376         KUNIT_CASE(sysctl_test_api_dointvec_table_len_is_zero),
 377         KUNIT_CASE(sysctl_test_api_dointvec_table_read_but_position_set),
 378         KUNIT_CASE(sysctl_test_dointvec_read_happy_single_positive),
 379         KUNIT_CASE(sysctl_test_dointvec_read_happy_single_negative),
 380         KUNIT_CASE(sysctl_test_dointvec_write_happy_single_positive),
 381         KUNIT_CASE(sysctl_test_dointvec_write_happy_single_negative),
 382         KUNIT_CASE(sysctl_test_api_dointvec_write_single_less_int_min),
 383         KUNIT_CASE(sysctl_test_api_dointvec_write_single_greater_int_max),
 384         {}
 385 };
 386
 387 static struct kunit_suite sysctl_test_suite = {
 388         .name = "sysctl_test",
 389         .test_cases = sysctl_test_cases,
 390 };
 391
 392 kunit_test_suite(sysctl_test_suite);