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 i; 174 175 ptr_id(NULL); 176 177 /* 178 * With an empty shadow variable hash table, expect not to find 179 * any matches. 180 */ 181 sv = shadow_get(&objs[0], SV_ID1); 182 if (!sv) 183 pr_info(" got expected NULL result\n"); 184 185 /* pass 1: init & alloc a char+int pair of svars for each objs */ 186 for (i = 0; i < NUM_OBJS; i++) { 187 pnfields1[i] = &nfields1[i]; 188 ptr_id(pnfields1[i]); 189 190 if (i % 2) { 191 sv1[i] = shadow_alloc(&objs[i], SV_ID1, 192 sizeof(pnfields1[i]), GFP_KERNEL, 193 shadow_ctor, &pnfields1[i]); 194 } else { 195 sv1[i] = shadow_get_or_alloc(&objs[i], SV_ID1, 196 sizeof(pnfields1[i]), GFP_KERNEL, 197 shadow_ctor, &pnfields1[i]); 198 } 199 if (!sv1[i]) 200 return -ENOMEM; 201 202 pnfields2[i] = &nfields2[i]; 203 ptr_id(pnfields2[i]); 204 sv2[i] = shadow_alloc(&objs[i], SV_ID2, sizeof(pnfields2[i]), 205 GFP_KERNEL, shadow_ctor, &pnfields2[i]); 206 if (!sv2[i]) 207 return -ENOMEM; 208 } 209 210 /* pass 2: verify we find allocated svars and where they point to */ 211 for (i = 0; i < NUM_OBJS; i++) { 212 /* check the "char" svar for all objects */ 213 sv = shadow_get(&objs[i], SV_ID1); 214 if (!sv) 215 return -EINVAL; 216 if ((char **)sv == sv1[i] && *sv1[i] == pnfields1[i]) 217 pr_info(" got expected PTR%d -> PTR%d result\n", 218 ptr_id(sv1[i]), ptr_id(*sv1[i])); 219 220 /* check the "int" svar for all objects */ 221 sv = shadow_get(&objs[i], SV_ID2); 222 if (!sv) 223 return -EINVAL; 224 if ((int **)sv == sv2[i] && *sv2[i] == pnfields2[i]) 225 pr_info(" got expected PTR%d -> PTR%d result\n", 226 ptr_id(sv2[i]), ptr_id(*sv2[i])); 227 } 228 229 /* pass 3: verify that 'get_or_alloc' returns already allocated svars */ 230 for (i = 0; i < NUM_OBJS; i++) { 231 pndup[i] = &nfields1[i]; 232 ptr_id(pndup[i]); 233 234 sv = shadow_get_or_alloc(&objs[i], SV_ID1, sizeof(pndup[i]), 235 GFP_KERNEL, shadow_ctor, &pndup[i]); 236 if (!sv) 237 return -EINVAL; 238 if ((char **)sv == sv1[i] && *sv1[i] == pnfields1[i]) 239 pr_info(" got expected PTR%d -> PTR%d result\n", 240 ptr_id(sv1[i]), ptr_id(*sv1[i])); 241 } 242 243 /* pass 4: free <objs[*], SV_ID1> pairs of svars, verify removal */ 244 for (i = 0; i < NUM_OBJS; i++) { 245 shadow_free(&objs[i], SV_ID1, shadow_dtor); /* 'char' pairs */ 246 sv = shadow_get(&objs[i], SV_ID1); 247 if (!sv) 248 pr_info(" got expected NULL result\n"); 249 } 250 251 /* pass 5: check we still find <objs[*], SV_ID2> svar pairs */ 252 for (i = 0; i < NUM_OBJS; i++) { 253 sv = shadow_get(&objs[i], SV_ID2); /* 'int' pairs */ 254 if (!sv) 255 return -EINVAL; 256 if ((int **)sv == sv2[i] && *sv2[i] == pnfields2[i]) 257 pr_info(" got expected PTR%d -> PTR%d result\n", 258 ptr_id(sv2[i]), ptr_id(*sv2[i])); 259 } 260 261 /* pass 6: free all the <objs[*], SV_ID2> svar pairs too. */ 262 shadow_free_all(SV_ID2, NULL); /* 'int' pairs */ 263 for (i = 0; i < NUM_OBJS; i++) { 264 sv = shadow_get(&objs[i], SV_ID2); 265 if (!sv) 266 pr_info(" got expected NULL result\n"); 267 } 268 269 free_ptr_list(); 270 271 return 0; 272 } 273 274 static void test_klp_shadow_vars_exit(void) 275 { 276 } 277 278 module_init(test_klp_shadow_vars_init); 279 module_exit(test_klp_shadow_vars_exit); 280 MODULE_LICENSE("GPL"); 281 MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>"); 282 MODULE_DESCRIPTION("Livepatch test: shadow variables"); 283