278 lines
6.4 KiB
C
278 lines
6.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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// Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com>
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/livepatch.h>
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#include <linux/slab.h>
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/*
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* Keep a small list of pointers so that we can print address-agnostic
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* pointer values. Use a rolling integer count to differentiate the values.
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* Ironically we could have used the shadow variable API to do this, but
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* let's not lean too heavily on the very code we're testing.
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*/
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static LIST_HEAD(ptr_list);
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struct shadow_ptr {
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void *ptr;
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int id;
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struct list_head list;
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};
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static void free_ptr_list(void)
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{
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struct shadow_ptr *sp, *tmp_sp;
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list_for_each_entry_safe(sp, tmp_sp, &ptr_list, list) {
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list_del(&sp->list);
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kfree(sp);
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}
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}
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static int ptr_id(void *ptr)
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{
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struct shadow_ptr *sp;
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static int count;
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list_for_each_entry(sp, &ptr_list, list) {
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if (sp->ptr == ptr)
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return sp->id;
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}
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sp = kmalloc(sizeof(*sp), GFP_ATOMIC);
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if (!sp)
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return -ENOMEM;
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sp->ptr = ptr;
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sp->id = count++;
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list_add(&sp->list, &ptr_list);
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return sp->id;
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}
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/*
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* Shadow variable wrapper functions that echo the function and arguments
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* to the kernel log for testing verification. Don't display raw pointers,
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* but use the ptr_id() value instead.
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*/
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static void *shadow_get(void *obj, unsigned long id)
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{
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int **sv;
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sv = klp_shadow_get(obj, id);
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pr_info("klp_%s(obj=PTR%d, id=0x%lx) = PTR%d\n",
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__func__, ptr_id(obj), id, ptr_id(sv));
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return sv;
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}
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static void *shadow_alloc(void *obj, unsigned long id, size_t size,
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gfp_t gfp_flags, klp_shadow_ctor_t ctor,
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void *ctor_data)
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{
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int **var = ctor_data;
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int **sv;
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sv = klp_shadow_alloc(obj, id, size, gfp_flags, ctor, var);
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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",
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__func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
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ptr_id(*var), ptr_id(sv));
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return sv;
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}
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static void *shadow_get_or_alloc(void *obj, unsigned long id, size_t size,
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gfp_t gfp_flags, klp_shadow_ctor_t ctor,
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void *ctor_data)
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{
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int **var = ctor_data;
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int **sv;
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sv = klp_shadow_get_or_alloc(obj, id, size, gfp_flags, ctor, var);
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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",
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__func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
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ptr_id(*var), ptr_id(sv));
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return sv;
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}
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static void shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor)
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{
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klp_shadow_free(obj, id, dtor);
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pr_info("klp_%s(obj=PTR%d, id=0x%lx, dtor=PTR%d)\n",
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__func__, ptr_id(obj), id, ptr_id(dtor));
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}
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static void shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor)
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{
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klp_shadow_free_all(id, dtor);
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pr_info("klp_%s(id=0x%lx, dtor=PTR%d)\n",
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__func__, id, ptr_id(dtor));
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}
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/* Shadow variable constructor - remember simple pointer data */
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static int shadow_ctor(void *obj, void *shadow_data, void *ctor_data)
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{
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int **sv = shadow_data;
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int **var = ctor_data;
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if (!var)
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return -EINVAL;
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*sv = *var;
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pr_info("%s: PTR%d -> PTR%d\n",
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__func__, ptr_id(sv), ptr_id(*var));
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return 0;
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}
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static void shadow_dtor(void *obj, void *shadow_data)
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{
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int **sv = shadow_data;
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pr_info("%s(obj=PTR%d, shadow_data=PTR%d)\n",
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__func__, ptr_id(obj), ptr_id(sv));
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}
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static int test_klp_shadow_vars_init(void)
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{
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void *obj = THIS_MODULE;
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int id = 0x1234;
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gfp_t gfp_flags = GFP_KERNEL;
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int var1, var2, var3, var4;
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int *pv1, *pv2, *pv3, *pv4;
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int **sv1, **sv2, **sv3, **sv4;
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int **sv;
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pv1 = &var1;
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pv2 = &var2;
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pv3 = &var3;
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pv4 = &var4;
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ptr_id(NULL);
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ptr_id(pv1);
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ptr_id(pv2);
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ptr_id(pv3);
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ptr_id(pv4);
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/*
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* With an empty shadow variable hash table, expect not to find
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* any matches.
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*/
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sv = shadow_get(obj, id);
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if (!sv)
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pr_info(" got expected NULL result\n");
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/*
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* Allocate a few shadow variables with different <obj> and <id>.
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*/
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sv1 = shadow_alloc(obj, id, sizeof(pv1), gfp_flags, shadow_ctor, &pv1);
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if (!sv1)
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return -ENOMEM;
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sv2 = shadow_alloc(obj + 1, id, sizeof(pv2), gfp_flags, shadow_ctor, &pv2);
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if (!sv2)
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return -ENOMEM;
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sv3 = shadow_alloc(obj, id + 1, sizeof(pv3), gfp_flags, shadow_ctor, &pv3);
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if (!sv3)
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return -ENOMEM;
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/*
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* Verify we can find our new shadow variables and that they point
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* to expected data.
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*/
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sv = shadow_get(obj, id);
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if (!sv)
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return -EINVAL;
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if (sv == sv1 && *sv1 == pv1)
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pr_info(" got expected PTR%d -> PTR%d result\n",
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ptr_id(sv1), ptr_id(*sv1));
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sv = shadow_get(obj + 1, id);
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if (!sv)
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return -EINVAL;
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if (sv == sv2 && *sv2 == pv2)
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pr_info(" got expected PTR%d -> PTR%d result\n",
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ptr_id(sv2), ptr_id(*sv2));
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sv = shadow_get(obj, id + 1);
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if (!sv)
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return -EINVAL;
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if (sv == sv3 && *sv3 == pv3)
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pr_info(" got expected PTR%d -> PTR%d result\n",
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ptr_id(sv3), ptr_id(*sv3));
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/*
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* Allocate or get a few more, this time with the same <obj>, <id>.
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* The second invocation should return the same shadow var.
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*/
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sv4 = shadow_get_or_alloc(obj + 2, id, sizeof(pv4), gfp_flags, shadow_ctor, &pv4);
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if (!sv4)
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return -ENOMEM;
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sv = shadow_get_or_alloc(obj + 2, id, sizeof(pv4), gfp_flags, shadow_ctor, &pv4);
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if (!sv)
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return -EINVAL;
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if (sv == sv4 && *sv4 == pv4)
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pr_info(" got expected PTR%d -> PTR%d result\n",
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ptr_id(sv4), ptr_id(*sv4));
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/*
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* Free the <obj=*, id> shadow variables and check that we can no
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* longer find them.
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*/
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shadow_free(obj, id, shadow_dtor); /* sv1 */
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sv = shadow_get(obj, id);
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if (!sv)
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pr_info(" got expected NULL result\n");
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shadow_free(obj + 1, id, shadow_dtor); /* sv2 */
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sv = shadow_get(obj + 1, id);
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if (!sv)
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pr_info(" got expected NULL result\n");
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shadow_free(obj + 2, id, shadow_dtor); /* sv4 */
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sv = shadow_get(obj + 2, id);
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if (!sv)
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pr_info(" got expected NULL result\n");
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/*
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* We should still find an <id+1> variable.
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*/
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sv = shadow_get(obj, id + 1);
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if (!sv)
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return -EINVAL;
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if (sv == sv3 && *sv3 == pv3)
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pr_info(" got expected PTR%d -> PTR%d result\n",
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ptr_id(sv3), ptr_id(*sv3));
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/*
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* Free all the <id+1> variables, too.
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*/
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shadow_free_all(id + 1, shadow_dtor); /* sv3 */
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sv = shadow_get(obj, id);
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if (!sv)
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pr_info(" shadow_get() got expected NULL result\n");
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free_ptr_list();
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return 0;
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}
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static void test_klp_shadow_vars_exit(void)
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{
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}
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module_init(test_klp_shadow_vars_init);
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module_exit(test_klp_shadow_vars_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
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MODULE_DESCRIPTION("Livepatch test: shadow variables");
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