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"); 302