| /* Kernel module help for x86. |
| Copyright (C) 2001 Rusty Russell. |
| |
| 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, write to the Free Software |
| Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| */ |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #include <linux/moduleloader.h> |
| #include <linux/elf.h> |
| #include <linux/vmalloc.h> |
| #include <linux/fs.h> |
| #include <linux/string.h> |
| #include <linux/kernel.h> |
| #include <linux/kasan.h> |
| #include <linux/bug.h> |
| #include <linux/mm.h> |
| #include <linux/gfp.h> |
| #include <linux/jump_label.h> |
| #include <linux/random.h> |
| |
| #include <asm/page.h> |
| #include <asm/pgtable.h> |
| |
| #if 0 |
| #define DEBUGP(fmt, ...) \ |
| printk(KERN_DEBUG fmt, ##__VA_ARGS__) |
| #else |
| #define DEBUGP(fmt, ...) \ |
| do { \ |
| if (0) \ |
| printk(KERN_DEBUG fmt, ##__VA_ARGS__); \ |
| } while (0) |
| #endif |
| |
| #ifdef CONFIG_RANDOMIZE_BASE |
| static unsigned long module_load_offset; |
| static int randomize_modules = 1; |
| |
| /* Mutex protects the module_load_offset. */ |
| static DEFINE_MUTEX(module_kaslr_mutex); |
| |
| static int __init parse_nokaslr(char *p) |
| { |
| randomize_modules = 0; |
| return 0; |
| } |
| early_param("nokaslr", parse_nokaslr); |
| |
| static unsigned long int get_module_load_offset(void) |
| { |
| if (randomize_modules) { |
| mutex_lock(&module_kaslr_mutex); |
| /* |
| * Calculate the module_load_offset the first time this |
| * code is called. Once calculated it stays the same until |
| * reboot. |
| */ |
| if (module_load_offset == 0) |
| module_load_offset = |
| (get_random_int() % 1024 + 1) * PAGE_SIZE; |
| mutex_unlock(&module_kaslr_mutex); |
| } |
| return module_load_offset; |
| } |
| #else |
| static unsigned long int get_module_load_offset(void) |
| { |
| return 0; |
| } |
| #endif |
| |
| void *module_alloc(unsigned long size) |
| { |
| void *p; |
| |
| if (PAGE_ALIGN(size) > MODULES_LEN) |
| return NULL; |
| |
| p = __vmalloc_node_range(size, MODULE_ALIGN, |
| MODULES_VADDR + get_module_load_offset(), |
| MODULES_END, GFP_KERNEL | __GFP_HIGHMEM, |
| PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE, |
| __builtin_return_address(0)); |
| if (p && (kasan_module_alloc(p, size) < 0)) { |
| vfree(p); |
| return NULL; |
| } |
| |
| return p; |
| } |
| |
| #ifdef CONFIG_X86_32 |
| int apply_relocate(Elf32_Shdr *sechdrs, |
| const char *strtab, |
| unsigned int symindex, |
| unsigned int relsec, |
| struct module *me) |
| { |
| unsigned int i; |
| Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr; |
| Elf32_Sym *sym; |
| uint32_t *location; |
| |
| DEBUGP("Applying relocate section %u to %u\n", |
| relsec, sechdrs[relsec].sh_info); |
| for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { |
| /* This is where to make the change */ |
| location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr |
| + rel[i].r_offset; |
| /* This is the symbol it is referring to. Note that all |
| undefined symbols have been resolved. */ |
| sym = (Elf32_Sym *)sechdrs[symindex].sh_addr |
| + ELF32_R_SYM(rel[i].r_info); |
| |
| switch (ELF32_R_TYPE(rel[i].r_info)) { |
| case R_386_32: |
| /* We add the value into the location given */ |
| *location += sym->st_value; |
| break; |
| case R_386_PC32: |
| /* Add the value, subtract its position */ |
| *location += sym->st_value - (uint32_t)location; |
| break; |
| default: |
| pr_err("%s: Unknown relocation: %u\n", |
| me->name, ELF32_R_TYPE(rel[i].r_info)); |
| return -ENOEXEC; |
| } |
| } |
| return 0; |
| } |
| #else /*X86_64*/ |
| int apply_relocate_add(Elf64_Shdr *sechdrs, |
| const char *strtab, |
| unsigned int symindex, |
| unsigned int relsec, |
| struct module *me) |
| { |
| unsigned int i; |
| Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr; |
| Elf64_Sym *sym; |
| void *loc; |
| u64 val; |
| |
| DEBUGP("Applying relocate section %u to %u\n", |
| relsec, sechdrs[relsec].sh_info); |
| for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { |
| /* This is where to make the change */ |
| loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr |
| + rel[i].r_offset; |
| |
| /* This is the symbol it is referring to. Note that all |
| undefined symbols have been resolved. */ |
| sym = (Elf64_Sym *)sechdrs[symindex].sh_addr |
| + ELF64_R_SYM(rel[i].r_info); |
| |
| DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n", |
| (int)ELF64_R_TYPE(rel[i].r_info), |
| sym->st_value, rel[i].r_addend, (u64)loc); |
| |
| val = sym->st_value + rel[i].r_addend; |
| |
| switch (ELF64_R_TYPE(rel[i].r_info)) { |
| case R_X86_64_NONE: |
| break; |
| case R_X86_64_64: |
| *(u64 *)loc = val; |
| break; |
| case R_X86_64_32: |
| *(u32 *)loc = val; |
| if (val != *(u32 *)loc) |
| goto overflow; |
| break; |
| case R_X86_64_32S: |
| *(s32 *)loc = val; |
| if ((s64)val != *(s32 *)loc) |
| goto overflow; |
| break; |
| case R_X86_64_PC32: |
| val -= (u64)loc; |
| *(u32 *)loc = val; |
| #if 0 |
| if ((s64)val != *(s32 *)loc) |
| goto overflow; |
| #endif |
| break; |
| default: |
| pr_err("%s: Unknown rela relocation: %llu\n", |
| me->name, ELF64_R_TYPE(rel[i].r_info)); |
| return -ENOEXEC; |
| } |
| } |
| return 0; |
| |
| overflow: |
| pr_err("overflow in relocation type %d val %Lx\n", |
| (int)ELF64_R_TYPE(rel[i].r_info), val); |
| pr_err("`%s' likely not compiled with -mcmodel=kernel\n", |
| me->name); |
| return -ENOEXEC; |
| } |
| #endif |
| |
| int module_finalize(const Elf_Ehdr *hdr, |
| const Elf_Shdr *sechdrs, |
| struct module *me) |
| { |
| const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL, |
| *para = NULL; |
| char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; |
| |
| for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) { |
| if (!strcmp(".text", secstrings + s->sh_name)) |
| text = s; |
| if (!strcmp(".altinstructions", secstrings + s->sh_name)) |
| alt = s; |
| if (!strcmp(".smp_locks", secstrings + s->sh_name)) |
| locks = s; |
| if (!strcmp(".parainstructions", secstrings + s->sh_name)) |
| para = s; |
| } |
| |
| if (alt) { |
| /* patch .altinstructions */ |
| void *aseg = (void *)alt->sh_addr; |
| apply_alternatives(aseg, aseg + alt->sh_size); |
| } |
| if (locks && text) { |
| void *lseg = (void *)locks->sh_addr; |
| void *tseg = (void *)text->sh_addr; |
| alternatives_smp_module_add(me, me->name, |
| lseg, lseg + locks->sh_size, |
| tseg, tseg + text->sh_size); |
| } |
| |
| if (para) { |
| void *pseg = (void *)para->sh_addr; |
| apply_paravirt(pseg, pseg + para->sh_size); |
| } |
| |
| /* make jump label nops */ |
| jump_label_apply_nops(me); |
| |
| return 0; |
| } |
| |
| void module_arch_cleanup(struct module *mod) |
| { |
| alternatives_smp_module_del(mod); |
| } |