383 lines
9.4 KiB
C
383 lines
9.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* Kernel module help for x86.
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Copyright (C) 2001 Rusty Russell.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/moduleloader.h>
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#include <linux/elf.h>
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#include <linux/vmalloc.h>
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#include <linux/fs.h>
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#include <linux/string.h>
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#include <linux/kernel.h>
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#include <linux/kasan.h>
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#include <linux/bug.h>
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#include <linux/mm.h>
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#include <linux/gfp.h>
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#include <linux/jump_label.h>
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#include <linux/random.h>
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#include <linux/memory.h>
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#include <asm/text-patching.h>
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#include <asm/page.h>
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#include <asm/setup.h>
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#include <asm/unwind.h>
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#if 0
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#define DEBUGP(fmt, ...) \
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printk(KERN_DEBUG fmt, ##__VA_ARGS__)
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#else
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#define DEBUGP(fmt, ...) \
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do { \
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if (0) \
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printk(KERN_DEBUG fmt, ##__VA_ARGS__); \
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} while (0)
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#endif
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#ifdef CONFIG_RANDOMIZE_BASE
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static unsigned long module_load_offset;
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/* Mutex protects the module_load_offset. */
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static DEFINE_MUTEX(module_kaslr_mutex);
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static unsigned long int get_module_load_offset(void)
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{
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if (kaslr_enabled()) {
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mutex_lock(&module_kaslr_mutex);
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/*
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* Calculate the module_load_offset the first time this
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* code is called. Once calculated it stays the same until
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* reboot.
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*/
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if (module_load_offset == 0)
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module_load_offset =
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get_random_u32_inclusive(1, 1024) * PAGE_SIZE;
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mutex_unlock(&module_kaslr_mutex);
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}
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return module_load_offset;
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}
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#else
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static unsigned long int get_module_load_offset(void)
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{
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return 0;
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}
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#endif
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void *module_alloc(unsigned long size)
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{
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gfp_t gfp_mask = GFP_KERNEL;
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void *p;
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if (PAGE_ALIGN(size) > MODULES_LEN)
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return NULL;
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p = __vmalloc_node_range(size, MODULE_ALIGN,
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MODULES_VADDR + get_module_load_offset(),
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MODULES_END, gfp_mask, PAGE_KERNEL,
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VM_FLUSH_RESET_PERMS | VM_DEFER_KMEMLEAK,
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NUMA_NO_NODE, __builtin_return_address(0));
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if (p && (kasan_alloc_module_shadow(p, size, gfp_mask) < 0)) {
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vfree(p);
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return NULL;
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}
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return p;
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}
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#ifdef CONFIG_X86_32
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int apply_relocate(Elf32_Shdr *sechdrs,
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const char *strtab,
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unsigned int symindex,
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unsigned int relsec,
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struct module *me)
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{
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unsigned int i;
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Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
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Elf32_Sym *sym;
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uint32_t *location;
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DEBUGP("Applying relocate section %u to %u\n",
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relsec, sechdrs[relsec].sh_info);
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for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
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/* This is where to make the change */
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location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
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+ rel[i].r_offset;
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/* This is the symbol it is referring to. Note that all
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undefined symbols have been resolved. */
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sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
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+ ELF32_R_SYM(rel[i].r_info);
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switch (ELF32_R_TYPE(rel[i].r_info)) {
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case R_386_32:
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/* We add the value into the location given */
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*location += sym->st_value;
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break;
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case R_386_PC32:
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case R_386_PLT32:
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/* Add the value, subtract its position */
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*location += sym->st_value - (uint32_t)location;
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break;
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default:
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pr_err("%s: Unknown relocation: %u\n",
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me->name, ELF32_R_TYPE(rel[i].r_info));
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return -ENOEXEC;
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}
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}
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return 0;
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}
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#else /*X86_64*/
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static int __write_relocate_add(Elf64_Shdr *sechdrs,
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const char *strtab,
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unsigned int symindex,
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unsigned int relsec,
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struct module *me,
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void *(*write)(void *dest, const void *src, size_t len),
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bool apply)
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{
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unsigned int i;
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Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
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Elf64_Sym *sym;
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void *loc;
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u64 val;
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u64 zero = 0ULL;
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DEBUGP("%s relocate section %u to %u\n",
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apply ? "Applying" : "Clearing",
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relsec, sechdrs[relsec].sh_info);
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for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
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size_t size;
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/* This is where to make the change */
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loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
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+ rel[i].r_offset;
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/* This is the symbol it is referring to. Note that all
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undefined symbols have been resolved. */
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sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
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+ ELF64_R_SYM(rel[i].r_info);
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DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
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(int)ELF64_R_TYPE(rel[i].r_info),
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sym->st_value, rel[i].r_addend, (u64)loc);
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val = sym->st_value + rel[i].r_addend;
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switch (ELF64_R_TYPE(rel[i].r_info)) {
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case R_X86_64_NONE:
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continue; /* nothing to write */
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case R_X86_64_64:
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size = 8;
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break;
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case R_X86_64_32:
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if (val != *(u32 *)&val)
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goto overflow;
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size = 4;
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break;
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case R_X86_64_32S:
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if ((s64)val != *(s32 *)&val)
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goto overflow;
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size = 4;
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break;
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case R_X86_64_PC32:
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case R_X86_64_PLT32:
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val -= (u64)loc;
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size = 4;
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break;
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case R_X86_64_PC64:
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val -= (u64)loc;
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size = 8;
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break;
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default:
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pr_err("%s: Unknown rela relocation: %llu\n",
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me->name, ELF64_R_TYPE(rel[i].r_info));
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return -ENOEXEC;
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}
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if (apply) {
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if (memcmp(loc, &zero, size)) {
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pr_err("x86/modules: Invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n",
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(int)ELF64_R_TYPE(rel[i].r_info), loc, val);
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return -ENOEXEC;
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}
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write(loc, &val, size);
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} else {
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if (memcmp(loc, &val, size)) {
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pr_warn("x86/modules: Invalid relocation target, existing value does not match expected value for type %d, loc %p, val %Lx\n",
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(int)ELF64_R_TYPE(rel[i].r_info), loc, val);
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return -ENOEXEC;
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}
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write(loc, &zero, size);
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}
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}
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return 0;
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overflow:
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pr_err("overflow in relocation type %d val %Lx\n",
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(int)ELF64_R_TYPE(rel[i].r_info), val);
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pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
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me->name);
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return -ENOEXEC;
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}
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static int write_relocate_add(Elf64_Shdr *sechdrs,
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const char *strtab,
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unsigned int symindex,
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unsigned int relsec,
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struct module *me,
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bool apply)
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{
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int ret;
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bool early = me->state == MODULE_STATE_UNFORMED;
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void *(*write)(void *, const void *, size_t) = memcpy;
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if (!early) {
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write = text_poke;
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mutex_lock(&text_mutex);
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}
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ret = __write_relocate_add(sechdrs, strtab, symindex, relsec, me,
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write, apply);
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if (!early) {
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text_poke_sync();
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mutex_unlock(&text_mutex);
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}
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return ret;
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}
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int apply_relocate_add(Elf64_Shdr *sechdrs,
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const char *strtab,
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unsigned int symindex,
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unsigned int relsec,
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struct module *me)
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{
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return write_relocate_add(sechdrs, strtab, symindex, relsec, me, true);
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}
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#ifdef CONFIG_LIVEPATCH
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void clear_relocate_add(Elf64_Shdr *sechdrs,
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const char *strtab,
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unsigned int symindex,
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unsigned int relsec,
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struct module *me)
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{
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write_relocate_add(sechdrs, strtab, symindex, relsec, me, false);
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}
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#endif
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#endif
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int module_finalize(const Elf_Ehdr *hdr,
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const Elf_Shdr *sechdrs,
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struct module *me)
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{
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const Elf_Shdr *s, *alt = NULL, *locks = NULL,
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*para = NULL, *orc = NULL, *orc_ip = NULL,
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*retpolines = NULL, *returns = NULL, *ibt_endbr = NULL,
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*calls = NULL, *cfi = NULL;
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char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
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for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
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if (!strcmp(".altinstructions", secstrings + s->sh_name))
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alt = s;
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if (!strcmp(".smp_locks", secstrings + s->sh_name))
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locks = s;
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if (!strcmp(".parainstructions", secstrings + s->sh_name))
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para = s;
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if (!strcmp(".orc_unwind", secstrings + s->sh_name))
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orc = s;
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if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name))
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orc_ip = s;
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if (!strcmp(".retpoline_sites", secstrings + s->sh_name))
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retpolines = s;
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if (!strcmp(".return_sites", secstrings + s->sh_name))
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returns = s;
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if (!strcmp(".call_sites", secstrings + s->sh_name))
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calls = s;
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if (!strcmp(".cfi_sites", secstrings + s->sh_name))
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cfi = s;
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if (!strcmp(".ibt_endbr_seal", secstrings + s->sh_name))
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ibt_endbr = s;
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}
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/*
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* See alternative_instructions() for the ordering rules between the
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* various patching types.
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*/
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if (para) {
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void *pseg = (void *)para->sh_addr;
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apply_paravirt(pseg, pseg + para->sh_size);
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}
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if (retpolines || cfi) {
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void *rseg = NULL, *cseg = NULL;
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unsigned int rsize = 0, csize = 0;
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if (retpolines) {
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rseg = (void *)retpolines->sh_addr;
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rsize = retpolines->sh_size;
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}
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if (cfi) {
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cseg = (void *)cfi->sh_addr;
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csize = cfi->sh_size;
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}
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apply_fineibt(rseg, rseg + rsize, cseg, cseg + csize);
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}
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if (retpolines) {
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void *rseg = (void *)retpolines->sh_addr;
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apply_retpolines(rseg, rseg + retpolines->sh_size);
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}
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if (returns) {
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void *rseg = (void *)returns->sh_addr;
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apply_returns(rseg, rseg + returns->sh_size);
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}
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if (alt) {
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/* patch .altinstructions */
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void *aseg = (void *)alt->sh_addr;
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apply_alternatives(aseg, aseg + alt->sh_size);
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}
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if (calls || para) {
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struct callthunk_sites cs = {};
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if (calls) {
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cs.call_start = (void *)calls->sh_addr;
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cs.call_end = (void *)calls->sh_addr + calls->sh_size;
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}
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if (para) {
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cs.pv_start = (void *)para->sh_addr;
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cs.pv_end = (void *)para->sh_addr + para->sh_size;
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}
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callthunks_patch_module_calls(&cs, me);
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}
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if (ibt_endbr) {
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void *iseg = (void *)ibt_endbr->sh_addr;
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apply_ibt_endbr(iseg, iseg + ibt_endbr->sh_size);
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}
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if (locks) {
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void *lseg = (void *)locks->sh_addr;
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void *text = me->core_layout.base;
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void *text_end = text + me->core_layout.text_size;
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alternatives_smp_module_add(me, me->name,
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lseg, lseg + locks->sh_size,
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text, text_end);
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}
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if (orc && orc_ip)
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unwind_module_init(me, (void *)orc_ip->sh_addr, orc_ip->sh_size,
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(void *)orc->sh_addr, orc->sh_size);
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return 0;
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}
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void module_arch_cleanup(struct module *mod)
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{
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alternatives_smp_module_del(mod);
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}
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