+++ /dev/null
-/*
- * livepatch.c - x86-specific Kernel Live Patching Core
- *
- * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
- * Copyright (C) 2014 SUSE
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, see <http://www.gnu.org/licenses/>.
- */
-
-#include <linux/module.h>
-#include <linux/uaccess.h>
-#include <asm/elf.h>
-#include <asm/livepatch.h>
-
-/**
- * klp_write_module_reloc() - write a relocation in a module
- * @mod: module in which the section to be modified is found
- * @type: ELF relocation type (see asm/elf.h)
- * @loc: address that the relocation should be written to
- * @value: relocation value (sym address + addend)
- *
- * This function writes a relocation to the specified location for
- * a particular module.
- */
-int klp_write_module_reloc(struct module *mod, unsigned long type,
- unsigned long loc, unsigned long value)
-{
- size_t size = 4;
- unsigned long val;
- unsigned long core = (unsigned long)mod->core_layout.base;
- unsigned long core_size = mod->core_layout.size;
-
- switch (type) {
- case R_X86_64_NONE:
- return 0;
- case R_X86_64_64:
- val = value;
- size = 8;
- break;
- case R_X86_64_32:
- val = (u32)value;
- break;
- case R_X86_64_32S:
- val = (s32)value;
- break;
- case R_X86_64_PC32:
- val = (u32)(value - loc);
- break;
- default:
- /* unsupported relocation type */
- return -EINVAL;
- }
-
- if (loc < core || loc >= core + core_size)
- /* loc does not point to any symbol inside the module */
- return -EINVAL;
-
- return probe_kernel_write((void *)loc, &val, size);
-}
#include <linux/list.h>
#include <linux/kallsyms.h>
#include <linux/livepatch.h>
+#include <linux/elf.h>
+#include <linux/moduleloader.h>
#include <asm/cacheflush.h>
/**
return -EINVAL;
}
-/*
- * external symbols are located outside the parent object (where the parent
- * object is either vmlinux or the kmod being patched).
- */
-static int klp_find_external_symbol(struct module *pmod, const char *name,
- unsigned long *addr)
+static int klp_resolve_symbols(Elf_Shdr *relasec, struct module *pmod)
{
- const struct kernel_symbol *sym;
-
- /* first, check if it's an exported symbol */
- preempt_disable();
- sym = find_symbol(name, NULL, NULL, true, true);
- if (sym) {
- *addr = sym->value;
- preempt_enable();
- return 0;
- }
- preempt_enable();
+ int i, cnt, vmlinux, ret;
+ char objname[MODULE_NAME_LEN];
+ char symname[KSYM_NAME_LEN];
+ char *strtab = pmod->core_kallsyms.strtab;
+ Elf_Rela *relas;
+ Elf_Sym *sym;
+ unsigned long sympos, addr;
/*
- * Check if it's in another .o within the patch module. This also
- * checks that the external symbol is unique.
+ * Since the field widths for objname and symname in the sscanf()
+ * call are hard-coded and correspond to MODULE_NAME_LEN and
+ * KSYM_NAME_LEN respectively, we must make sure that MODULE_NAME_LEN
+ * and KSYM_NAME_LEN have the values we expect them to have.
+ *
+ * Because the value of MODULE_NAME_LEN can differ among architectures,
+ * we use the smallest/strictest upper bound possible (56, based on
+ * the current definition of MODULE_NAME_LEN) to prevent overflows.
*/
- return klp_find_object_symbol(pmod->name, name, 0, addr);
+ BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 128);
+
+ relas = (Elf_Rela *) relasec->sh_addr;
+ /* For each rela in this klp relocation section */
+ for (i = 0; i < relasec->sh_size / sizeof(Elf_Rela); i++) {
+ sym = pmod->core_kallsyms.symtab + ELF_R_SYM(relas[i].r_info);
+ if (sym->st_shndx != SHN_LIVEPATCH) {
+ pr_err("symbol %s is not marked as a livepatch symbol",
+ strtab + sym->st_name);
+ return -EINVAL;
+ }
+
+ /* Format: .klp.sym.objname.symname,sympos */
+ cnt = sscanf(strtab + sym->st_name,
+ ".klp.sym.%55[^.].%127[^,],%lu",
+ objname, symname, &sympos);
+ if (cnt != 3) {
+ pr_err("symbol %s has an incorrectly formatted name",
+ strtab + sym->st_name);
+ return -EINVAL;
+ }
+
+ /* klp_find_object_symbol() treats a NULL objname as vmlinux */
+ vmlinux = !strcmp(objname, "vmlinux");
+ ret = klp_find_object_symbol(vmlinux ? NULL : objname,
+ symname, sympos, &addr);
+ if (ret)
+ return ret;
+
+ sym->st_value = addr;
+ }
+
+ return 0;
}
static int klp_write_object_relocations(struct module *pmod,
struct klp_object *obj)
{
- int ret = 0;
- unsigned long val;
- struct klp_reloc *reloc;
+ int i, cnt, ret = 0;
+ const char *objname, *secname;
+ char sec_objname[MODULE_NAME_LEN];
+ Elf_Shdr *sec;
if (WARN_ON(!klp_is_object_loaded(obj)))
return -EINVAL;
- if (WARN_ON(!obj->relocs))
- return -EINVAL;
+ objname = klp_is_module(obj) ? obj->name : "vmlinux";
module_disable_ro(pmod);
+ /* For each klp relocation section */
+ for (i = 1; i < pmod->klp_info->hdr.e_shnum; i++) {
+ sec = pmod->klp_info->sechdrs + i;
+ secname = pmod->klp_info->secstrings + sec->sh_name;
+ if (!(sec->sh_flags & SHF_RELA_LIVEPATCH))
+ continue;
- for (reloc = obj->relocs; reloc->name; reloc++) {
- /* discover the address of the referenced symbol */
- if (reloc->external) {
- if (reloc->sympos > 0) {
- pr_err("non-zero sympos for external reloc symbol '%s' is not supported\n",
- reloc->name);
- ret = -EINVAL;
- goto out;
- }
- ret = klp_find_external_symbol(pmod, reloc->name, &val);
- } else
- ret = klp_find_object_symbol(obj->name,
- reloc->name,
- reloc->sympos,
- &val);
+ /*
+ * Format: .klp.rela.sec_objname.section_name
+ * See comment in klp_resolve_symbols() for an explanation
+ * of the selected field width value.
+ */
+ cnt = sscanf(secname, ".klp.rela.%55[^.]", sec_objname);
+ if (cnt != 1) {
+ pr_err("section %s has an incorrectly formatted name",
+ secname);
+ ret = -EINVAL;
+ break;
+ }
+
+ if (strcmp(objname, sec_objname))
+ continue;
+
+ ret = klp_resolve_symbols(sec, pmod);
if (ret)
- goto out;
+ break;
- ret = klp_write_module_reloc(pmod, reloc->type, reloc->loc,
- val + reloc->addend);
- if (ret) {
- pr_err("relocation failed for symbol '%s' at 0x%016lx (%d)\n",
- reloc->name, val, ret);
- goto out;
- }
+ ret = apply_relocate_add(pmod->klp_info->sechdrs,
+ pmod->core_kallsyms.strtab,
+ pmod->klp_info->symndx, i, pmod);
+ if (ret)
+ break;
}
-out:
module_enable_ro(pmod);
return ret;
}
struct klp_func *func;
int ret;
- if (obj->relocs) {
- ret = klp_write_object_relocations(patch->mod, obj);
- if (ret)
- return ret;
- }
+ ret = klp_write_object_relocations(patch->mod, obj);
+ if (ret)
+ return ret;
klp_for_each_func(obj, func) {
ret = klp_find_object_symbol(obj->name, func->old_name,
{
int ret;
+ if (!is_livepatch_module(patch->mod)) {
+ pr_err("module %s is not marked as a livepatch module",
+ patch->mod->name);
+ return -EINVAL;
+ }
+
if (!klp_initialized())
return -ENODEV;
projects / mirror_ubuntu-artful-kernel.git / commitdiff