130 lines
3.2 KiB
C
130 lines
3.2 KiB
C
/*
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* kallsyms_relocs.c - resolve non-exported symbols
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*
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* Copyright (C) 2018 SUSE
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* Author: Nicolai Stange <nstange@suse.de>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/kallsyms.h>
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#include "kallsyms_relocs.h"
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struct find_args
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{
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struct klp_kallsyms_reloc reloc;
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unsigned long match_count;
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};
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static int __find_callback(void *data, const char *name, unsigned long addr)
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{
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struct find_args *args = data;
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if (strcmp(args->reloc.symname, name))
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return 0;
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args->match_count++;
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/*
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* Finish the search when the symbol is found for the desired
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* position or the position is not defined.
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*/
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if (!args->reloc.sympos || args->match_count == args->reloc.sympos) {
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*args->reloc.addr = (void *)addr;
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return 1;
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}
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return 0;
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}
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static
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int (*klpe_module_kallsyms_on_each_symbol)(const char *modname,
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int (*fn)(void *, const char *,
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unsigned long),
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void *data);
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static int __klp_resolve_kallsyms_relocs(struct klp_kallsyms_reloc *relocs,
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unsigned long count)
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{
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unsigned long i;
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struct find_args args;
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for (i = 0; i < count; ++i) {
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*relocs[i].addr = NULL;
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args.reloc = relocs[i];
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args.match_count = 0;
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if (args.reloc.objname) {
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klpe_module_kallsyms_on_each_symbol(args.reloc.objname,
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__find_callback,
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&args);
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} else {
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kallsyms_on_each_symbol(__find_callback, &args);
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}
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if (!*relocs[i].addr) {
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if (relocs[i].objname) {
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pr_err("livepatch: symbol %s:%s not resolved\n",
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relocs[i].objname, relocs[i].symname);
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} else {
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pr_err("livepatch: symbol %s not resolved\n",
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relocs[i].symname);
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}
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return -ENOENT;
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}
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}
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return 0;
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}
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struct module *(*klpe_find_module)(const char *name);
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/* Bootstrap: resolve non-exported module_kallsyms_on_each_symbol() */
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int klp_kallsyms_relocs_init(void)
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{
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static struct klp_kallsyms_reloc bootstrap_relocs[] = {
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{ "module_kallsyms_on_each_symbol",
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(void *)&klpe_module_kallsyms_on_each_symbol },
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{ "find_module", (void *)&klpe_find_module },
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};
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/* Already initialized? */
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if (klpe_module_kallsyms_on_each_symbol)
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return 0;
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/*
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* All relocations are against symbols from vmlinux, the yet
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* unresolved klpe_module_kallsyms_on_each_symbol() will not
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* get invoked and the call below will work fine at this stage
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* already.
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*/
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return __klp_resolve_kallsyms_relocs(bootstrap_relocs,
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ARRAY_SIZE(bootstrap_relocs));
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}
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int klp_resolve_kallsyms_relocs(struct klp_kallsyms_reloc *relocs,
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unsigned long count)
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{
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int ret;
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ret = klp_kallsyms_relocs_init();
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if (ret)
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return ret;
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return __klp_resolve_kallsyms_relocs(relocs, count);
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}
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