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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 | // SPDX-License-Identifier: GPL-2.0 // Copyright (C) 2019 SUSE #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/slab.h> #include <linux/module.h> #include <linux/kernel.h> #include <linux/printk.h> #include <linux/livepatch.h> #define CONSOLE_LOGLEVEL_STATE 1 /* Version 2 supports migration. */ #define CONSOLE_LOGLEVEL_STATE_VERSION 2 static const char *const module_state[] = { [MODULE_STATE_LIVE] = "[MODULE_STATE_LIVE] Normal state", [MODULE_STATE_COMING] = "[MODULE_STATE_COMING] Full formed, running module_init", [MODULE_STATE_GOING] = "[MODULE_STATE_GOING] Going away", [MODULE_STATE_UNFORMED] = "[MODULE_STATE_UNFORMED] Still setting it up", }; static void callback_info(const char *callback, struct klp_object *obj) { if (obj->mod) pr_info("%s: %s -> %s\n", callback, obj->mod->name, module_state[obj->mod->state]); else pr_info("%s: vmlinux\n", callback); } static struct klp_patch patch; static int allocate_loglevel_state(void) { struct klp_state *loglevel_state, *prev_loglevel_state; prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE); if (prev_loglevel_state) { pr_info("%s: space to store console_loglevel already allocated\n", __func__); return 0; } loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE); if (!loglevel_state) return -EINVAL; loglevel_state->data = kzalloc(sizeof(console_loglevel), GFP_KERNEL); if (!loglevel_state->data) return -ENOMEM; pr_info("%s: allocating space to store console_loglevel\n", __func__); return 0; } static void fix_console_loglevel(void) { struct klp_state *loglevel_state, *prev_loglevel_state; loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE); if (!loglevel_state) return; prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE); if (prev_loglevel_state) { pr_info("%s: taking over the console_loglevel change\n", __func__); loglevel_state->data = prev_loglevel_state->data; return; } pr_info("%s: fixing console_loglevel\n", __func__); *(int *)loglevel_state->data = console_loglevel; console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH; } static void restore_console_loglevel(void) { struct klp_state *loglevel_state, *prev_loglevel_state; prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE); if (prev_loglevel_state) { pr_info("%s: passing the console_loglevel change back to the old livepatch\n", __func__); return; } loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE); if (!loglevel_state) return; pr_info("%s: restoring console_loglevel\n", __func__); console_loglevel = *(int *)loglevel_state->data; } static void free_loglevel_state(void) { struct klp_state *loglevel_state, *prev_loglevel_state; prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE); if (prev_loglevel_state) { pr_info("%s: keeping space to store console_loglevel\n", __func__); return; } loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE); if (!loglevel_state) return; pr_info("%s: freeing space for the stored console_loglevel\n", __func__); kfree(loglevel_state->data); } /* Executed on object patching (ie, patch enablement) */ static int pre_patch_callback(struct klp_object *obj) { callback_info(__func__, obj); return allocate_loglevel_state(); } /* Executed on object unpatching (ie, patch disablement) */ static void post_patch_callback(struct klp_object *obj) { callback_info(__func__, obj); fix_console_loglevel(); } /* Executed on object unpatching (ie, patch disablement) */ static void pre_unpatch_callback(struct klp_object *obj) { callback_info(__func__, obj); restore_console_loglevel(); } /* Executed on object unpatching (ie, patch disablement) */ static void post_unpatch_callback(struct klp_object *obj) { callback_info(__func__, obj); free_loglevel_state(); } static struct klp_func no_funcs[] = { {} }; static struct klp_object objs[] = { { .name = NULL, /* vmlinux */ .funcs = no_funcs, .callbacks = { .pre_patch = pre_patch_callback, .post_patch = post_patch_callback, .pre_unpatch = pre_unpatch_callback, .post_unpatch = post_unpatch_callback, }, }, { } }; static struct klp_state states[] = { { .id = CONSOLE_LOGLEVEL_STATE, .version = CONSOLE_LOGLEVEL_STATE_VERSION, }, { } }; static struct klp_patch patch = { .mod = THIS_MODULE, .objs = objs, .states = states, .replace = true, }; static int test_klp_callbacks_demo_init(void) { return klp_enable_patch(&patch); } static void test_klp_callbacks_demo_exit(void) { } module_init(test_klp_callbacks_demo_init); module_exit(test_klp_callbacks_demo_exit); MODULE_LICENSE("GPL"); MODULE_INFO(livepatch, "Y"); MODULE_AUTHOR("Petr Mladek <pmladek@suse.com>"); MODULE_DESCRIPTION("Livepatch test: system state modification"); |