lib/livepatch/test_klp_shadow_vars.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 // Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com>
0003
0004 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0005
0006 #include <linux/module.h>
0007 #include <linux/kernel.h>
0008 #include <linux/list.h>
0009 #include <linux/livepatch.h>
0010 #include <linux/slab.h>
0011
0012 /*
0013  * Keep a small list of pointers so that we can print address-agnostic
0014  * pointer values.  Use a rolling integer count to differentiate the values.
0015  * Ironically we could have used the shadow variable API to do this, but
0016  * let's not lean too heavily on the very code we're testing.
0017  */
0018 static LIST_HEAD(ptr_list);
0019 struct shadow_ptr {
0020     void *ptr;
0021     int id;
0022     struct list_head list;
0023 };
0024
0025 static void free_ptr_list(void)
0026 {
0027     struct shadow_ptr *sp, *tmp_sp;
0028
0029     list_for_each_entry_safe(sp, tmp_sp, &ptr_list, list) {
0030         list_del(&sp->list);
0031         kfree(sp);
0032     }
0033 }
0034
0035 static int ptr_id(void *ptr)
0036 {
0037     struct shadow_ptr *sp;
0038     static int count;
0039
0040     list_for_each_entry(sp, &ptr_list, list) {
0041         if (sp->ptr == ptr)
0042             return sp->id;
0043     }
0044
0045     sp = kmalloc(sizeof(*sp), GFP_ATOMIC);
0046     if (!sp)
0047         return -ENOMEM;
0048     sp->ptr = ptr;
0049     sp->id = count++;
0050
0051     list_add(&sp->list, &ptr_list);
0052
0053     return sp->id;
0054 }
0055
0056 /*
0057  * Shadow variable wrapper functions that echo the function and arguments
0058  * to the kernel log for testing verification.  Don't display raw pointers,
0059  * but use the ptr_id() value instead.
0060  */
0061 static void *shadow_get(void *obj, unsigned long id)
0062 {
0063     int **sv;
0064
0065     sv = klp_shadow_get(obj, id);
0066     pr_info("klp_%s(obj=PTR%d, id=0x%lx) = PTR%d\n",
0067         __func__, ptr_id(obj), id, ptr_id(sv));
0068
0069     return sv;
0070 }
0071
0072 static void *shadow_alloc(void *obj, unsigned long id, size_t size,
0073               gfp_t gfp_flags, klp_shadow_ctor_t ctor,
0074               void *ctor_data)
0075 {
0076     int **var = ctor_data;
0077     int **sv;
0078
0079     sv = klp_shadow_alloc(obj, id, size, gfp_flags, ctor, var);
0080     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",
0081         __func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
0082         ptr_id(*var), ptr_id(sv));
0083
0084     return sv;
0085 }
0086
0087 static void *shadow_get_or_alloc(void *obj, unsigned long id, size_t size,
0088                  gfp_t gfp_flags, klp_shadow_ctor_t ctor,
0089                  void *ctor_data)
0090 {
0091     int **var = ctor_data;
0092     int **sv;
0093
0094     sv = klp_shadow_get_or_alloc(obj, id, size, gfp_flags, ctor, var);
0095     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",
0096         __func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
0097         ptr_id(*var), ptr_id(sv));
0098
0099     return sv;
0100 }
0101
0102 static void shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor)
0103 {
0104     klp_shadow_free(obj, id, dtor);
0105     pr_info("klp_%s(obj=PTR%d, id=0x%lx, dtor=PTR%d)\n",
0106         __func__, ptr_id(obj), id, ptr_id(dtor));
0107 }
0108
0109 static void shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor)
0110 {
0111     klp_shadow_free_all(id, dtor);
0112     pr_info("klp_%s(id=0x%lx, dtor=PTR%d)\n", __func__, id, ptr_id(dtor));
0113 }
0114
0115
0116 /* Shadow variable constructor - remember simple pointer data */
0117 static int shadow_ctor(void *obj, void *shadow_data, void *ctor_data)
0118 {
0119     int **sv = shadow_data;
0120     int **var = ctor_data;
0121
0122     if (!var)
0123         return -EINVAL;
0124
0125     *sv = *var;
0126     pr_info("%s: PTR%d -> PTR%d\n", __func__, ptr_id(sv), ptr_id(*var));
0127
0128     return 0;
0129 }
0130
0131 /*
0132  * With more than one item to free in the list, order is not determined and
0133  * shadow_dtor will not be passed to shadow_free_all() which would make the
0134  * test fail. (see pass 6)
0135  */
0136 static void shadow_dtor(void *obj, void *shadow_data)
0137 {
0138     int **sv = shadow_data;
0139
0140     pr_info("%s(obj=PTR%d, shadow_data=PTR%d)\n",
0141         __func__, ptr_id(obj), ptr_id(sv));
0142 }
0143
0144 /* number of objects we simulate that need shadow vars */
0145 #define NUM_OBJS 3
0146
0147 /* dynamically created obj fields have the following shadow var id values */
0148 #define SV_ID1 0x1234
0149 #define SV_ID2 0x1235
0150
0151 /*
0152  * The main test case adds/removes new fields (shadow var) to each of these
0153  * test structure instances. The last group of fields in the struct represent
0154  * the idea that shadow variables may be added and removed to and from the
0155  * struct during execution.
0156  */
0157 struct test_object {
0158      /* add anything here below and avoid to define an empty struct */
0159     struct shadow_ptr sp;
0160
0161     /* these represent shadow vars added and removed with SV_ID{1,2} */
0162     /* char nfield1; */
0163     /* int  nfield2; */
0164 };
0165
0166 static int test_klp_shadow_vars_init(void)
0167 {
0168     struct test_object objs[NUM_OBJS];
0169     char nfields1[NUM_OBJS], *pnfields1[NUM_OBJS], **sv1[NUM_OBJS];
0170     char *pndup[NUM_OBJS];
0171     int nfields2[NUM_OBJS], *pnfields2[NUM_OBJS], **sv2[NUM_OBJS];
0172     void **sv;
0173     int ret;
0174     int i;
0175
0176     ptr_id(NULL);
0177
0178     /*
0179      * With an empty shadow variable hash table, expect not to find
0180      * any matches.
0181      */
0182     sv = shadow_get(&objs[0], SV_ID1);
0183     if (!sv)
0184         pr_info("  got expected NULL result\n");
0185
0186     /* pass 1: init & alloc a char+int pair of svars for each objs */
0187     for (i = 0; i < NUM_OBJS; i++) {
0188         pnfields1[i] = &nfields1[i];
0189         ptr_id(pnfields1[i]);
0190
0191         if (i % 2) {
0192             sv1[i] = shadow_alloc(&objs[i], SV_ID1,
0193                     sizeof(pnfields1[i]), GFP_KERNEL,
0194                     shadow_ctor, &pnfields1[i]);
0195         } else {
0196             sv1[i] = shadow_get_or_alloc(&objs[i], SV_ID1,
0197                     sizeof(pnfields1[i]), GFP_KERNEL,
0198                     shadow_ctor, &pnfields1[i]);
0199         }
0200         if (!sv1[i]) {
0201             ret = -ENOMEM;
0202             goto out;
0203         }
0204
0205         pnfields2[i] = &nfields2[i];
0206         ptr_id(pnfields2[i]);
0207         sv2[i] = shadow_alloc(&objs[i], SV_ID2, sizeof(pnfields2[i]),
0208                     GFP_KERNEL, shadow_ctor, &pnfields2[i]);
0209         if (!sv2[i]) {
0210             ret = -ENOMEM;
0211             goto out;
0212         }
0213     }
0214
0215     /* pass 2: verify we find allocated svars and where they point to */
0216     for (i = 0; i < NUM_OBJS; i++) {
0217         /* check the "char" svar for all objects */
0218         sv = shadow_get(&objs[i], SV_ID1);
0219         if (!sv) {
0220             ret = -EINVAL;
0221             goto out;
0222         }
0223         if ((char **)sv == sv1[i] && *sv1[i] == pnfields1[i])
0224             pr_info("  got expected PTR%d -> PTR%d result\n",
0225                 ptr_id(sv1[i]), ptr_id(*sv1[i]));
0226
0227         /* check the "int" svar for all objects */
0228         sv = shadow_get(&objs[i], SV_ID2);
0229         if (!sv) {
0230             ret = -EINVAL;
0231             goto out;
0232         }
0233         if ((int **)sv == sv2[i] && *sv2[i] == pnfields2[i])
0234             pr_info("  got expected PTR%d -> PTR%d result\n",
0235                 ptr_id(sv2[i]), ptr_id(*sv2[i]));
0236     }
0237
0238     /* pass 3: verify that 'get_or_alloc' returns already allocated svars */
0239     for (i = 0; i < NUM_OBJS; i++) {
0240         pndup[i] = &nfields1[i];
0241         ptr_id(pndup[i]);
0242
0243         sv = shadow_get_or_alloc(&objs[i], SV_ID1, sizeof(pndup[i]),
0244                     GFP_KERNEL, shadow_ctor, &pndup[i]);
0245         if (!sv) {
0246             ret = -EINVAL;
0247             goto out;
0248         }
0249         if ((char **)sv == sv1[i] && *sv1[i] == pnfields1[i])
0250             pr_info("  got expected PTR%d -> PTR%d result\n",
0251                     ptr_id(sv1[i]), ptr_id(*sv1[i]));
0252     }
0253
0254     /* pass 4: free <objs[*], SV_ID1> pairs of svars, verify removal */
0255     for (i = 0; i < NUM_OBJS; i++) {
0256         shadow_free(&objs[i], SV_ID1, shadow_dtor); /* 'char' pairs */
0257         sv = shadow_get(&objs[i], SV_ID1);
0258         if (!sv)
0259             pr_info("  got expected NULL result\n");
0260     }
0261
0262     /* pass 5: check we still find <objs[*], SV_ID2> svar pairs */
0263     for (i = 0; i < NUM_OBJS; i++) {
0264         sv = shadow_get(&objs[i], SV_ID2);  /* 'int' pairs */
0265         if (!sv) {
0266             ret = -EINVAL;
0267             goto out;
0268         }
0269         if ((int **)sv == sv2[i] && *sv2[i] == pnfields2[i])
0270             pr_info("  got expected PTR%d -> PTR%d result\n",
0271                     ptr_id(sv2[i]), ptr_id(*sv2[i]));
0272     }
0273
0274     /* pass 6: free all the <objs[*], SV_ID2> svar pairs too. */
0275     shadow_free_all(SV_ID2, NULL);      /* 'int' pairs */
0276     for (i = 0; i < NUM_OBJS; i++) {
0277         sv = shadow_get(&objs[i], SV_ID2);
0278         if (!sv)
0279             pr_info("  got expected NULL result\n");
0280     }
0281
0282     free_ptr_list();
0283
0284     return 0;
0285 out:
0286     shadow_free_all(SV_ID1, NULL);      /* 'char' pairs */
0287     shadow_free_all(SV_ID2, NULL);      /* 'int' pairs */
0288     free_ptr_list();
0289
0290     return ret;
0291 }
0292
0293 static void test_klp_shadow_vars_exit(void)
0294 {
0295 }
0296
0297 module_init(test_klp_shadow_vars_init);
0298 module_exit(test_klp_shadow_vars_exit);
0299 MODULE_LICENSE("GPL");
0300 MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
0301 MODULE_DESCRIPTION("Livepatch test: shadow variables");