lib/livepatch/test_klp_shadow_vars.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com>
   3
   4 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   5
   6 #include <linux/module.h>
   7 #include <linux/kernel.h>
   8 #include <linux/list.h>
   9 #include <linux/livepatch.h>
  10 #include <linux/slab.h>
  11
  12 /*
  13  * Keep a small list of pointers so that we can print address-agnostic
  14  * pointer values.  Use a rolling integer count to differentiate the values.
  15  * Ironically we could have used the shadow variable API to do this, but
  16  * let's not lean too heavily on the very code we're testing.
  17  */
  18 static LIST_HEAD(ptr_list);
  19 struct shadow_ptr {
  20         void *ptr;
  21         int id;
  22         struct list_head list;
  23 };
  24
  25 static void free_ptr_list(void)
  26 {
  27         struct shadow_ptr *sp, *tmp_sp;
  28
  29         list_for_each_entry_safe(sp, tmp_sp, &ptr_list, list) {
  30                 list_del(&sp->list);
  31                 kfree(sp);
  32         }
  33 }
  34
  35 static int ptr_id(void *ptr)
  36 {
  37         struct shadow_ptr *sp;
  38         static int count;
  39
  40         list_for_each_entry(sp, &ptr_list, list) {
  41                 if (sp->ptr == ptr)
  42                         return sp->id;
  43         }
  44
  45         sp = kmalloc(sizeof(*sp), GFP_ATOMIC);
  46         if (!sp)
  47                 return -ENOMEM;
  48         sp->ptr = ptr;
  49         sp->id = count++;
  50
  51         list_add(&sp->list, &ptr_list);
  52
  53         return sp->id;
  54 }
  55
  56 /*
  57  * Shadow variable wrapper functions that echo the function and arguments
  58  * to the kernel log for testing verification.  Don't display raw pointers,
  59  * but use the ptr_id() value instead.
  60  */
  61 static void *shadow_get(void *obj, unsigned long id)
  62 {
  63         int **sv;
  64
  65         sv = klp_shadow_get(obj, id);
  66         pr_info("klp_%s(obj=PTR%d, id=0x%lx) = PTR%d\n",
  67                 __func__, ptr_id(obj), id, ptr_id(sv));
  68
  69         return sv;
  70 }
  71
  72 static void *shadow_alloc(void *obj, unsigned long id, size_t size,
  73                           gfp_t gfp_flags, klp_shadow_ctor_t ctor,
  74                           void *ctor_data)
  75 {
  76         int **var = ctor_data;
  77         int **sv;
  78
  79         sv = klp_shadow_alloc(obj, id, size, gfp_flags, ctor, var);
  80         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",
  81                 __func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
  82                 ptr_id(*var), ptr_id(sv));
  83
  84         return sv;
  85 }
  86
  87 static void *shadow_get_or_alloc(void *obj, unsigned long id, size_t size,
  88                                  gfp_t gfp_flags, klp_shadow_ctor_t ctor,
  89                                  void *ctor_data)
  90 {
  91         int **var = ctor_data;
  92         int **sv;
  93
  94         sv = klp_shadow_get_or_alloc(obj, id, size, gfp_flags, ctor, var);
  95         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",
  96                 __func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
  97                 ptr_id(*var), ptr_id(sv));
  98
  99         return sv;
 100 }
 101
 102 static void shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor)
 103 {
 104         klp_shadow_free(obj, id, dtor);
 105         pr_info("klp_%s(obj=PTR%d, id=0x%lx, dtor=PTR%d)\n",
 106                 __func__, ptr_id(obj), id, ptr_id(dtor));
 107 }
 108
 109 static void shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor)
 110 {
 111         klp_shadow_free_all(id, dtor);
 112         pr_info("klp_%s(id=0x%lx, dtor=PTR%d)\n", __func__, id, ptr_id(dtor));
 113 }
 114
 115
 116 /* Shadow variable constructor - remember simple pointer data */
 117 static int shadow_ctor(void *obj, void *shadow_data, void *ctor_data)
 118 {
 119         int **sv = shadow_data;
 120         int **var = ctor_data;
 121
 122         if (!var)
 123                 return -EINVAL;
 124
 125         *sv = *var;
 126         pr_info("%s: PTR%d -> PTR%d\n", __func__, ptr_id(sv), ptr_id(*var));
 127
 128         return 0;
 129 }
 130
 131 /*
 132  * With more than one item to free in the list, order is not determined and
 133  * shadow_dtor will not be passed to shadow_free_all() which would make the
 134  * test fail. (see pass 6)
 135  */
 136 static void shadow_dtor(void *obj, void *shadow_data)
 137 {
 138         int **sv = shadow_data;
 139
 140         pr_info("%s(obj=PTR%d, shadow_data=PTR%d)\n",
 141                 __func__, ptr_id(obj), ptr_id(sv));
 142 }
 143
 144 /* number of objects we simulate that need shadow vars */
 145 #define NUM_OBJS 3
 146
 147 /* dynamically created obj fields have the following shadow var id values */
 148 #define SV_ID1 0x1234
 149 #define SV_ID2 0x1235
 150
 151 /*
 152  * The main test case adds/removes new fields (shadow var) to each of these
 153  * test structure instances. The last group of fields in the struct represent
 154  * the idea that shadow variables may be added and removed to and from the
 155  * struct during execution.
 156  */
 157 struct test_object {
 158          /* add anything here below and avoid to define an empty struct */
 159         struct shadow_ptr sp;
 160
 161         /* these represent shadow vars added and removed with SV_ID{1,2} */
 162         /* char nfield1; */
 163         /* int  nfield2; */
 164 };
 165
 166 static int test_klp_shadow_vars_init(void)
 167 {
 168         struct test_object objs[NUM_OBJS];
 169         char nfields1[NUM_OBJS], *pnfields1[NUM_OBJS], **sv1[NUM_OBJS];
 170         char *pndup[NUM_OBJS];
 171         int nfields2[NUM_OBJS], *pnfields2[NUM_OBJS], **sv2[NUM_OBJS];
 172         void **sv;
 173         int ret;
 174         int i;
 175
 176         ptr_id(NULL);
 177
 178         /*
 179          * With an empty shadow variable hash table, expect not to find
 180          * any matches.
 181          */
 182         sv = shadow_get(&objs[0], SV_ID1);
 183         if (!sv)
 184                 pr_info("  got expected NULL result\n");
 185
 186         /* pass 1: init & alloc a char+int pair of svars for each objs */
 187         for (i = 0; i < NUM_OBJS; i++) {
 188                 pnfields1[i] = &nfields1[i];
 189                 ptr_id(pnfields1[i]);
 190
 191                 if (i % 2) {
 192                         sv1[i] = shadow_alloc(&objs[i], SV_ID1,
 193                                         sizeof(pnfields1[i]), GFP_KERNEL,
 194                                         shadow_ctor, &pnfields1[i]);
 195                 } else {
 196                         sv1[i] = shadow_get_or_alloc(&objs[i], SV_ID1,
 197                                         sizeof(pnfields1[i]), GFP_KERNEL,
 198                                         shadow_ctor, &pnfields1[i]);
 199                 }
 200                 if (!sv1[i]) {
 201                         ret = -ENOMEM;
 202                         goto out;
 203                 }
 204
 205                 pnfields2[i] = &nfields2[i];
 206                 ptr_id(pnfields2[i]);
 207                 sv2[i] = shadow_alloc(&objs[i], SV_ID2, sizeof(pnfields2[i]),
 208                                         GFP_KERNEL, shadow_ctor, &pnfields2[i]);
 209                 if (!sv2[i]) {
 210                         ret = -ENOMEM;
 211                         goto out;
 212                 }
 213         }
 214
 215         /* pass 2: verify we find allocated svars and where they point to */
 216         for (i = 0; i < NUM_OBJS; i++) {
 217                 /* check the "char" svar for all objects */
 218                 sv = shadow_get(&objs[i], SV_ID1);
 219                 if (!sv) {
 220                         ret = -EINVAL;
 221                         goto out;
 222                 }
 223                 if ((char **)sv == sv1[i] && *sv1[i] == pnfields1[i])
 224                         pr_info("  got expected PTR%d -> PTR%d result\n",
 225                                 ptr_id(sv1[i]), ptr_id(*sv1[i]));
 226
 227                 /* check the "int" svar for all objects */
 228                 sv = shadow_get(&objs[i], SV_ID2);
 229                 if (!sv) {
 230                         ret = -EINVAL;
 231                         goto out;
 232                 }
 233                 if ((int **)sv == sv2[i] && *sv2[i] == pnfields2[i])
 234                         pr_info("  got expected PTR%d -> PTR%d result\n",
 235                                 ptr_id(sv2[i]), ptr_id(*sv2[i]));
 236         }
 237
 238         /* pass 3: verify that 'get_or_alloc' returns already allocated svars */
 239         for (i = 0; i < NUM_OBJS; i++) {
 240                 pndup[i] = &nfields1[i];
 241                 ptr_id(pndup[i]);
 242
 243                 sv = shadow_get_or_alloc(&objs[i], SV_ID1, sizeof(pndup[i]),
 244                                         GFP_KERNEL, shadow_ctor, &pndup[i]);
 245                 if (!sv) {
 246                         ret = -EINVAL;
 247                         goto out;
 248                 }
 249                 if ((char **)sv == sv1[i] && *sv1[i] == pnfields1[i])
 250                         pr_info("  got expected PTR%d -> PTR%d result\n",
 251                                         ptr_id(sv1[i]), ptr_id(*sv1[i]));
 252         }
 253
 254         /* pass 4: free <objs[*], SV_ID1> pairs of svars, verify removal */
 255         for (i = 0; i < NUM_OBJS; i++) {
 256                 shadow_free(&objs[i], SV_ID1, shadow_dtor); /* 'char' pairs */
 257                 sv = shadow_get(&objs[i], SV_ID1);
 258                 if (!sv)
 259                         pr_info("  got expected NULL result\n");
 260         }
 261
 262         /* pass 5: check we still find <objs[*], SV_ID2> svar pairs */
 263         for (i = 0; i < NUM_OBJS; i++) {
 264                 sv = shadow_get(&objs[i], SV_ID2);      /* 'int' pairs */
 265                 if (!sv) {
 266                         ret = -EINVAL;
 267                         goto out;
 268                 }
 269                 if ((int **)sv == sv2[i] && *sv2[i] == pnfields2[i])
 270                         pr_info("  got expected PTR%d -> PTR%d result\n",
 271                                         ptr_id(sv2[i]), ptr_id(*sv2[i]));
 272         }
 273
 274         /* pass 6: free all the <objs[*], SV_ID2> svar pairs too. */
 275         shadow_free_all(SV_ID2, NULL);          /* 'int' pairs */
 276         for (i = 0; i < NUM_OBJS; i++) {
 277                 sv = shadow_get(&objs[i], SV_ID2);
 278                 if (!sv)
 279                         pr_info("  got expected NULL result\n");
 280         }
 281
 282         free_ptr_list();
 283
 284         return 0;
 285 out:
 286         shadow_free_all(SV_ID1, NULL);          /* 'char' pairs */
 287         shadow_free_all(SV_ID2, NULL);          /* 'int' pairs */
 288         free_ptr_list();
 289
 290         return ret;
 291 }
 292
 293 static void test_klp_shadow_vars_exit(void)
 294 {
 295 }
 296
 297 module_init(test_klp_shadow_vars_init);
 298 module_exit(test_klp_shadow_vars_exit);
 299 MODULE_LICENSE("GPL");
 300 MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
 301 MODULE_DESCRIPTION("Livepatch test: shadow variables");