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 if (!var) 124 return -EINVAL; 125 126 *sv = *var; 127 pr_info("%s: PTR%d -> PTR%d\n", 128 __func__, ptr_id(sv), ptr_id(*var)); 129 130 return 0; 131 } 132 133 static void shadow_dtor(void *obj, void *shadow_data) 134 { 135 int **sv = shadow_data; 136 137 pr_info("%s(obj=PTR%d, shadow_data=PTR%d)\n", 138 __func__, ptr_id(obj), ptr_id(sv)); 139 } 140 141 static int test_klp_shadow_vars_init(void) 142 { 143 void *obj = THIS_MODULE; 144 int id = 0x1234; 145 gfp_t gfp_flags = GFP_KERNEL; 146 147 int var1, var2, var3, var4; 148 int *pv1, *pv2, *pv3, *pv4; 149 int **sv1, **sv2, **sv3, **sv4; 150 151 int **sv; 152 153 pv1 = &var1; 154 pv2 = &var2; 155 pv3 = &var3; 156 pv4 = &var4; 157 158 ptr_id(NULL); 159 ptr_id(pv1); 160 ptr_id(pv2); 161 ptr_id(pv3); 162 ptr_id(pv4); 163 164 /* 165 * With an empty shadow variable hash table, expect not to find 166 * any matches. 167 */ 168 sv = shadow_get(obj, id); 169 if (!sv) 170 pr_info(" got expected NULL result\n"); 171 172 /* 173 * Allocate a few shadow variables with different <obj> and <id>. 174 */ 175 sv1 = shadow_alloc(obj, id, sizeof(pv1), gfp_flags, shadow_ctor, &pv1); 176 if (!sv1) 177 return -ENOMEM; 178 179 sv2 = shadow_alloc(obj + 1, id, sizeof(pv2), gfp_flags, shadow_ctor, &pv2); 180 if (!sv2) 181 return -ENOMEM; 182 183 sv3 = shadow_alloc(obj, id + 1, sizeof(pv3), gfp_flags, shadow_ctor, &pv3); 184 if (!sv3) 185 return -ENOMEM; 186 187 /* 188 * Verify we can find our new shadow variables and that they point 189 * to expected data. 190 */ 191 sv = shadow_get(obj, id); 192 if (!sv) 193 return -EINVAL; 194 if (sv == sv1 && *sv1 == pv1) 195 pr_info(" got expected PTR%d -> PTR%d result\n", 196 ptr_id(sv1), ptr_id(*sv1)); 197 198 sv = shadow_get(obj + 1, id); 199 if (!sv) 200 return -EINVAL; 201 if (sv == sv2 && *sv2 == pv2) 202 pr_info(" got expected PTR%d -> PTR%d result\n", 203 ptr_id(sv2), ptr_id(*sv2)); 204 sv = shadow_get(obj, id + 1); 205 if (!sv) 206 return -EINVAL; 207 if (sv == sv3 && *sv3 == pv3) 208 pr_info(" got expected PTR%d -> PTR%d result\n", 209 ptr_id(sv3), ptr_id(*sv3)); 210 211 /* 212 * Allocate or get a few more, this time with the same <obj>, <id>. 213 * The second invocation should return the same shadow var. 214 */ 215 sv4 = shadow_get_or_alloc(obj + 2, id, sizeof(pv4), gfp_flags, shadow_ctor, &pv4); 216 if (!sv4) 217 return -ENOMEM; 218 219 sv = shadow_get_or_alloc(obj + 2, id, sizeof(pv4), gfp_flags, shadow_ctor, &pv4); 220 if (!sv) 221 return -EINVAL; 222 if (sv == sv4 && *sv4 == pv4) 223 pr_info(" got expected PTR%d -> PTR%d result\n", 224 ptr_id(sv4), ptr_id(*sv4)); 225 226 /* 227 * Free the <obj=*, id> shadow variables and check that we can no 228 * longer find them. 229 */ 230 shadow_free(obj, id, shadow_dtor); /* sv1 */ 231 sv = shadow_get(obj, id); 232 if (!sv) 233 pr_info(" got expected NULL result\n"); 234 235 shadow_free(obj + 1, id, shadow_dtor); /* sv2 */ 236 sv = shadow_get(obj + 1, id); 237 if (!sv) 238 pr_info(" got expected NULL result\n"); 239 240 shadow_free(obj + 2, id, shadow_dtor); /* sv4 */ 241 sv = shadow_get(obj + 2, id); 242 if (!sv) 243 pr_info(" got expected NULL result\n"); 244 245 /* 246 * We should still find an <id+1> variable. 247 */ 248 sv = shadow_get(obj, id + 1); 249 if (!sv) 250 return -EINVAL; 251 if (sv == sv3 && *sv3 == pv3) 252 pr_info(" got expected PTR%d -> PTR%d result\n", 253 ptr_id(sv3), ptr_id(*sv3)); 254 255 /* 256 * Free all the <id+1> variables, too. 257 */ 258 shadow_free_all(id + 1, shadow_dtor); /* sv3 */ 259 sv = shadow_get(obj, id); 260 if (!sv) 261 pr_info(" shadow_get() got expected NULL result\n"); 262 263 264 free_ptr_list(); 265 266 return 0; 267 } 268 269 static void test_klp_shadow_vars_exit(void) 270 { 271 } 272 273 module_init(test_klp_shadow_vars_init); 274 module_exit(test_klp_shadow_vars_exit); 275 MODULE_LICENSE("GPL"); 276 MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>"); 277 MODULE_DESCRIPTION("Livepatch test: shadow variables"); 278