arch/x86/kernel/module.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*  Kernel module help for x86.
     Copyright (C) 2001 Rusty Russell.

 */

 #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 <linux/memory.h>

 #include <asm/text-patching.h>
 #include <asm/page.h>
 #include <asm/setup.h>
 #include <asm/unwind.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;

 /* Mutex protects the module_load_offset. */
 static DEFINE_MUTEX(module_kaslr_mutex);

 static unsigned long int get_module_load_offset(void)
 {
 	if (kaslr_enabled()) {
 		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 =
 				(prandom_u32_max(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)
 {
 	gfp_t gfp_mask = GFP_KERNEL;
 	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_mask,
 				    PAGE_KERNEL, VM_DEFER_KMEMLEAK, NUMA_NO_NODE,
 				    __builtin_return_address(0));
 	if (p && (kasan_alloc_module_shadow(p, size, gfp_mask) < 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:
 		case R_386_PLT32:
 			/* 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*/
 static int __apply_relocate_add(Elf64_Shdr *sechdrs,
 		   const char *strtab,
 		   unsigned int symindex,
 		   unsigned int relsec,
 		   struct module *me,
 		   void *(*write)(void *dest, const void *src, size_t len))
 {
 	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:
 			if (*(u64 *)loc != 0)
 				goto invalid_relocation;
 			write(loc, &val, 8);
 			break;
 		case R_X86_64_32:
 			if (*(u32 *)loc != 0)
 				goto invalid_relocation;
 			write(loc, &val, 4);
 			if (val != *(u32 *)loc)
 				goto overflow;
 			break;
 		case R_X86_64_32S:
 			if (*(s32 *)loc != 0)
 				goto invalid_relocation;
 			write(loc, &val, 4);
 			if ((s64)val != *(s32 *)loc)
 				goto overflow;
 			break;
 		case R_X86_64_PC32:
 		case R_X86_64_PLT32:
 			if (*(u32 *)loc != 0)
 				goto invalid_relocation;
 			val -= (u64)loc;
 			write(loc, &val, 4);
 #if 0
 			if ((s64)val != *(s32 *)loc)
 				goto overflow;
 #endif
 			break;
 		case R_X86_64_PC64:
 			if (*(u64 *)loc != 0)
 				goto invalid_relocation;
 			val -= (u64)loc;
 			write(loc, &val, 8);
 			break;
 		default:
 			pr_err("%s: Unknown rela relocation: %llu\n",
 			       me->name, ELF64_R_TYPE(rel[i].r_info));
 			return -ENOEXEC;
 		}
 	}
 	return 0;

 invalid_relocation:
 	pr_err("x86/modules: Skipping invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n",
 	       (int)ELF64_R_TYPE(rel[i].r_info), loc, val);
 	return -ENOEXEC;

 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;
 }

 int apply_relocate_add(Elf64_Shdr *sechdrs,
 		   const char *strtab,
 		   unsigned int symindex,
 		   unsigned int relsec,
 		   struct module *me)
 {
 	int ret;
 	bool early = me->state == MODULE_STATE_UNFORMED;
 	void *(*write)(void *, const void *, size_t) = memcpy;

 	if (!early) {
 		write = text_poke;
 		mutex_lock(&text_mutex);
 	}

 	ret = __apply_relocate_add(sechdrs, strtab, symindex, relsec, me,
 				   write);

 	if (!early) {
 		text_poke_sync();
 		mutex_unlock(&text_mutex);
 	}

 	return ret;
 }

 #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, *orc = NULL, *orc_ip = NULL,
 		*retpolines = NULL, *returns = NULL, *ibt_endbr = 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 (!strcmp(".orc_unwind", secstrings + s->sh_name))
 			orc = s;
 		if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name))
 			orc_ip = s;
 		if (!strcmp(".retpoline_sites", secstrings + s->sh_name))
 			retpolines = s;
 		if (!strcmp(".return_sites", secstrings + s->sh_name))
 			returns = s;
 		if (!strcmp(".ibt_endbr_seal", secstrings + s->sh_name))
 			ibt_endbr = s;
 	}

 	/*
 	 * See alternative_instructions() for the ordering rules between the
 	 * various patching types.
 	 */
 	if (para) {
 		void *pseg = (void *)para->sh_addr;
 		apply_paravirt(pseg, pseg + para->sh_size);
 	}
 	if (retpolines) {
 		void *rseg = (void *)retpolines->sh_addr;
 		apply_retpolines(rseg, rseg + retpolines->sh_size);
 	}
 	if (returns) {
 		void *rseg = (void *)returns->sh_addr;
 		apply_returns(rseg, rseg + returns->sh_size);
 	}
 	if (alt) {
 		/* patch .altinstructions */
 		void *aseg = (void *)alt->sh_addr;
 		apply_alternatives(aseg, aseg + alt->sh_size);
 	}
 	if (ibt_endbr) {
 		void *iseg = (void *)ibt_endbr->sh_addr;
 		apply_ibt_endbr(iseg, iseg + ibt_endbr->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 (orc && orc_ip)
 		unwind_module_init(me, (void *)orc_ip->sh_addr, orc_ip->sh_size,
 				   (void *)orc->sh_addr, orc->sh_size);

 	return 0;
 }

 void module_arch_cleanup(struct module *mod)
 {
 	alternatives_smp_module_del(mod);
 }
	// SPDX-License-Identifier: GPL-2.0-or-later
	/* Kernel module help for x86.
	Copyright (C) 2001 Rusty Russell.

	*/

	#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 <linux/memory.h>

	#include <asm/text-patching.h>
	#include <asm/page.h>
	#include <asm/setup.h>
	#include <asm/unwind.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;

	/* Mutex protects the module_load_offset. */
	static DEFINE_MUTEX(module_kaslr_mutex);

	static unsigned long int get_module_load_offset(void)
	{
	if (kaslr_enabled()) {
	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 =
	(prandom_u32_max(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)
	{
	gfp_t gfp_mask = GFP_KERNEL;
	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_mask,
	PAGE_KERNEL, VM_DEFER_KMEMLEAK, NUMA_NO_NODE,
	__builtin_return_address(0));
	if (p && (kasan_alloc_module_shadow(p, size, gfp_mask) < 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:
	case R_386_PLT32:
	/* 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/
	static int __apply_relocate_add(Elf64_Shdr *sechdrs,
	const char *strtab,
	unsigned int symindex,
	unsigned int relsec,
	struct module *me,
	void (write)(void dest, const void src, size_t len))
	{
	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:
	if ((u64 )loc != 0)
	goto invalid_relocation;
	write(loc, &val, 8);
	break;
	case R_X86_64_32:
	if ((u32 )loc != 0)
	goto invalid_relocation;
	write(loc, &val, 4);
	if (val != (u32 )loc)
	goto overflow;
	break;
	case R_X86_64_32S:
	if ((s32 )loc != 0)
	goto invalid_relocation;
	write(loc, &val, 4);
	if ((s64)val != (s32 )loc)
	goto overflow;
	break;
	case R_X86_64_PC32:
	case R_X86_64_PLT32:
	if ((u32 )loc != 0)
	goto invalid_relocation;
	val -= (u64)loc;
	write(loc, &val, 4);
	#if 0
	if ((s64)val != (s32 )loc)
	goto overflow;
	#endif
	break;
	case R_X86_64_PC64:
	if ((u64 )loc != 0)
	goto invalid_relocation;
	val -= (u64)loc;
	write(loc, &val, 8);
	break;
	default:
	pr_err("%s: Unknown rela relocation: %llu\n",
	me->name, ELF64_R_TYPE(rel[i].r_info));
	return -ENOEXEC;
	}
	}
	return 0;

	invalid_relocation:
	pr_err("x86/modules: Skipping invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n",
	(int)ELF64_R_TYPE(rel[i].r_info), loc, val);
	return -ENOEXEC;

	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;
	}

	int apply_relocate_add(Elf64_Shdr *sechdrs,
	const char *strtab,
	unsigned int symindex,
	unsigned int relsec,
	struct module *me)
	{
	int ret;
	bool early = me->state == MODULE_STATE_UNFORMED;
	void (write)(void , const void , size_t) = memcpy;

	if (!early) {
	write = text_poke;
	mutex_lock(&text_mutex);
	}

	ret = __apply_relocate_add(sechdrs, strtab, symindex, relsec, me,
	write);

	if (!early) {
	text_poke_sync();
	mutex_unlock(&text_mutex);
	}

	return ret;
	}

	#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, orc = NULL, *orc_ip = NULL,
	retpolines = NULL, returns = NULL, *ibt_endbr = 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 (!strcmp(".orc_unwind", secstrings + s->sh_name))
	orc = s;
	if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name))
	orc_ip = s;
	if (!strcmp(".retpoline_sites", secstrings + s->sh_name))
	retpolines = s;
	if (!strcmp(".return_sites", secstrings + s->sh_name))
	returns = s;
	if (!strcmp(".ibt_endbr_seal", secstrings + s->sh_name))
	ibt_endbr = s;
	}

	/*
	* See alternative_instructions() for the ordering rules between the
	* various patching types.
	*/
	if (para) {
	void pseg = (void )para->sh_addr;
	apply_paravirt(pseg, pseg + para->sh_size);
	}
	if (retpolines) {
	void rseg = (void )retpolines->sh_addr;
	apply_retpolines(rseg, rseg + retpolines->sh_size);
	}
	if (returns) {
	void rseg = (void )returns->sh_addr;
	apply_returns(rseg, rseg + returns->sh_size);
	}
	if (alt) {
	/* patch .altinstructions */
	void aseg = (void )alt->sh_addr;
	apply_alternatives(aseg, aseg + alt->sh_size);
	}
	if (ibt_endbr) {
	void iseg = (void )ibt_endbr->sh_addr;
	apply_ibt_endbr(iseg, iseg + ibt_endbr->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 (orc && orc_ip)
	unwind_module_init(me, (void *)orc_ip->sh_addr, orc_ip->sh_size,
	(void *)orc->sh_addr, orc->sh_size);

	return 0;
	}

	void module_arch_cleanup(struct module *mod)
	{
	alternatives_smp_module_del(mod);
	}