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", 113 __func__, id, ptr_id(dtor)); 114 } 115 116 117 /* Shadow variable constructor - remember simple pointer data */ 118 static int shadow_ctor(void *obj, void *shadow_data, void *ctor_data) 119 { 120 int **sv = shadow_data; 121 int *var = ctor_data; 122 123 *sv = var; 124 pr_info("%s: PTR%d -> PTR%d\n", 125 __func__, ptr_id(sv), ptr_id(var)); 126 127 return 0; 128 } 129 130 static void shadow_dtor(void *obj, void *shadow_data) 131 { 132 int **sv = shadow_data; 133 134 pr_info("%s(obj=PTR%d, shadow_data=PTR%d)\n", 135 __func__, ptr_id(obj), ptr_id(sv)); 136 } 137 138 static int test_klp_shadow_vars_init(void) 139 { 140 void *obj = THIS_MODULE; 141 int id = 0x1234; 142 size_t size = sizeof(int *); 143 gfp_t gfp_flags = GFP_KERNEL; 144 145 int var1, var2, var3, var4; 146 int **sv1, **sv2, **sv3, **sv4; 147 148 int **sv; 149 150 ptr_id(NULL); 151 ptr_id(&var1); 152 ptr_id(&var2); 153 ptr_id(&var3); 154 ptr_id(&var4); 155 156 /* 157 * With an empty shadow variable hash table, expect not to find 158 * any matches. 159 */ 160 sv = shadow_get(obj, id); 161 if (!sv) 162 pr_info(" got expected NULL result\n"); 163 164 /* 165 * Allocate a few shadow variables with different <obj> and <id>. 166 */ 167 sv1 = shadow_alloc(obj, id, size, gfp_flags, shadow_ctor, &var1); 168 if (!sv1) 169 return -ENOMEM; 170 171 sv2 = shadow_alloc(obj + 1, id, size, gfp_flags, shadow_ctor, &var2); 172 if (!sv2) 173 return -ENOMEM; 174 175 sv3 = shadow_alloc(obj, id + 1, size, gfp_flags, shadow_ctor, &var3); 176 if (!sv3) 177 return -ENOMEM; 178 179 /* 180 * Verify we can find our new shadow variables and that they point 181 * to expected data. 182 */ 183 sv = shadow_get(obj, id); 184 if (!sv) 185 return -EINVAL; 186 if (sv == sv1 && *sv1 == &var1) 187 pr_info(" got expected PTR%d -> PTR%d result\n", 188 ptr_id(sv1), ptr_id(*sv1)); 189 190 sv = shadow_get(obj + 1, id); 191 if (!sv) 192 return -EINVAL; 193 if (sv == sv2 && *sv2 == &var2) 194 pr_info(" got expected PTR%d -> PTR%d result\n", 195 ptr_id(sv2), ptr_id(*sv2)); 196 sv = shadow_get(obj, id + 1); 197 if (!sv) 198 return -EINVAL; 199 if (sv == sv3 && *sv3 == &var3) 200 pr_info(" got expected PTR%d -> PTR%d result\n", 201 ptr_id(sv3), ptr_id(*sv3)); 202 203 /* 204 * Allocate or get a few more, this time with the same <obj>, <id>. 205 * The second invocation should return the same shadow var. 206 */ 207 sv4 = shadow_get_or_alloc(obj + 2, id, size, gfp_flags, shadow_ctor, &var4); 208 if (!sv4) 209 return -ENOMEM; 210 211 sv = shadow_get_or_alloc(obj + 2, id, size, gfp_flags, shadow_ctor, &var4); 212 if (!sv) 213 return -EINVAL; 214 if (sv == sv4 && *sv4 == &var4) 215 pr_info(" got expected PTR%d -> PTR%d result\n", 216 ptr_id(sv4), ptr_id(*sv4)); 217 218 /* 219 * Free the <obj=*, id> shadow variables and check that we can no 220 * longer find them. 221 */ 222 shadow_free(obj, id, shadow_dtor); /* sv1 */ 223 sv = shadow_get(obj, id); 224 if (!sv) 225 pr_info(" got expected NULL result\n"); 226 227 shadow_free(obj + 1, id, shadow_dtor); /* sv2 */ 228 sv = shadow_get(obj + 1, id); 229 if (!sv) 230 pr_info(" got expected NULL result\n"); 231 232 shadow_free(obj + 2, id, shadow_dtor); /* sv4 */ 233 sv = shadow_get(obj + 2, id); 234 if (!sv) 235 pr_info(" got expected NULL result\n"); 236 237 /* 238 * We should still find an <id+1> variable. 239 */ 240 sv = shadow_get(obj, id + 1); 241 if (!sv) 242 return -EINVAL; 243 if (sv == sv3 && *sv3 == &var3) 244 pr_info(" got expected PTR%d -> PTR%d result\n", 245 ptr_id(sv3), ptr_id(*sv3)); 246 247 /* 248 * Free all the <id+1> variables, too. 249 */ 250 shadow_free_all(id + 1, shadow_dtor); /* sv3 */ 251 sv = shadow_get(obj, id); 252 if (!sv) 253 pr_info(" shadow_get() got expected NULL result\n"); 254 255 256 free_ptr_list(); 257 258 return 0; 259 } 260 261 static void test_klp_shadow_vars_exit(void) 262 { 263 } 264 265 module_init(test_klp_shadow_vars_init); 266 module_exit(test_klp_shadow_vars_exit); 267 MODULE_LICENSE("GPL"); 268 MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>"); 269 MODULE_DESCRIPTION("Livepatch test: shadow variables"); 270