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1) update README, add example code, 2) generate txt for thin archive under corresponding kmod and vmlinux dir
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,114 @@ | ||
| /* | ||
| * Copyright 2021 Google LLC | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * https://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| * | ||
| * Author: Yonghyun Hwang <yonghyun@google.com> | ||
| */ | ||
| /* | ||
| * This file implements example code to show | ||
| * | ||
| * 1) how to implement callbacks for kernel livepatch, | ||
| * | ||
| * 2) how to access global variables defined in kernel module or vmlinux. | ||
| * | ||
| * For more details, refer to ${llpatch}/templates/llpatch.h and | ||
| * ${llpatch}/templates/llpatch-callbacks.c | ||
| */ | ||
| #include <linux/module.h> | ||
| #include <linux/kernel.h> | ||
| #include <linux/livepatch.h> | ||
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|
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| #include "llpatch.h" | ||
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| typedef char c_array_t[PAGE_SIZE]; | ||
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| // c_array_t: type of global variable defined in kernel module | ||
| // apple_fruit: alias to the variable | ||
| // kernel/livepatch/test/test-attr-apple.c: path to the file w/ the variable | ||
| // fruit: name of variable in the file for the kernel module | ||
| LLPATCH_DECLARE_SYMBOL(c_array_t, apple_fruit, | ||
| kernel/livepatch/test/test-attr-apple.c, fruit); | ||
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| LLPATCH_DECLARE_SYMBOL( | ||
| c_array_t, banana_fruit, | ||
| kernel/livepatch/test/test-attr-banana.c, fruit); | ||
|
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| #define SHADOW_DATA_ID 1 | ||
|
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| /* Executed on object patching (ie, patch enablement) */ | ||
| static int pre_patch_callback(struct klp_object *obj) | ||
| { | ||
| char *shadow_apple, *shadow_banana; | ||
|
|
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| pr_info("\nAccessing llpatch symbol in %s\n", __func__); | ||
|
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| pr_info("apple_fruit is %s at %p\n", | ||
| LLPATCH_SYMBOL(apple_fruit), | ||
| LLPATCH_SYMBOL(apple_fruit)); | ||
| pr_info("banana_fruit is %s at %p\n", | ||
| LLPATCH_SYMBOL(banana_fruit), | ||
| LLPATCH_SYMBOL(banana_fruit)); | ||
|
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| /* | ||
| * @obj: pointer to parent object | ||
| * @id: data identifier | ||
| * @size: size of attached data | ||
| * @gfp_flags: GFP mask for allocation | ||
| * @ctor: custom constructor to initialize the shadow data (optional) | ||
| * @ctor_data: pointer to any data needed by @ctor (optional) | ||
| */ | ||
| shadow_apple = klp_shadow_alloc(/*obj*/LLPATCH_SYMBOL(apple_fruit), | ||
| /*id*/SHADOW_DATA_ID, | ||
| /*size*/sizeof(c_array_t), | ||
| /*gfp_flags*/GFP_KERNEL, | ||
| /*ctor*/NULL, /*ctor_data*/NULL); | ||
| strcpy(shadow_apple, "Pink Lady"); | ||
| pr_info("shadow for apple is added\n"); | ||
|
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| shadow_banana = klp_shadow_alloc(/*obj*/LLPATCH_SYMBOL(banana_fruit), | ||
| /*id*/SHADOW_DATA_ID, | ||
| /*size*/sizeof(c_array_t), | ||
| /*gfp_flags*/GFP_KERNEL, | ||
| /*ctor*/NULL, /*ctor_data*/NULL); | ||
| strcpy(shadow_banana, "Plantain"); | ||
| pr_info("shadow for banana is added\n"); | ||
|
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| pr_info("Done in %s\n\n", __func__); | ||
|
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| return 0; | ||
| } | ||
|
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| /* Executed after object patching */ | ||
| static void post_patch_callback(struct klp_object *obj) | ||
| { | ||
| } | ||
|
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| /* Executed on object unpatching */ | ||
| static void pre_unpatch_callback(struct klp_object *obj) | ||
| { | ||
| } | ||
|
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| /* Executed after object unpatching */ | ||
| static void post_unpatch_callback(struct klp_object *obj) | ||
| { | ||
| pr_info("\nAccessing llpatch symbol in %s\n", __func__); | ||
|
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| pr_info("freeing shadow data for apple at %p\n", LLPATCH_SYMBOL(apple_fruit)); | ||
| klp_shadow_free(LLPATCH_SYMBOL(apple_fruit), SHADOW_DATA_ID, NULL); | ||
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| pr_info("freeing shadow data for banana at %p\n", LLPATCH_SYMBOL(banana_fruit)); | ||
| klp_shadow_free(LLPATCH_SYMBOL(banana_fruit), SHADOW_DATA_ID, NULL); | ||
|
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| pr_info("Done in %s\n\n", __func__); | ||
| } |
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