1 files changed, 382 insertions, 0 deletions

diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
new file mode 100644
index 0000000000..5f71a0cf43
--- /dev/null
+++ b/arch/x86/kernel/module.c
@@ -0,0 +1,382 @@
+// 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 =
+				get_random_u32_inclusive(1, 1024) * 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_FLUSH_RESET_PERMS | 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 __write_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),
+		   bool apply)
+{
+	unsigned int i;
+	Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
+	Elf64_Sym *sym;
+	void *loc;
+	u64 val;
+	u64 zero = 0ULL;
+
+	DEBUGP("%s relocate section %u to %u\n",
+	       apply ? "Applying" : "Clearing",
+	       relsec, sechdrs[relsec].sh_info);
+	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
+		size_t size;
+
+		/* 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:
+			continue;  /* nothing to write */
+		case R_X86_64_64:
+			size = 8;
+			break;
+		case R_X86_64_32:
+			if (val != *(u32 *)&val)
+				goto overflow;
+			size = 4;
+			break;
+		case R_X86_64_32S:
+			if ((s64)val != *(s32 *)&val)
+				goto overflow;
+			size = 4;
+			break;
+		case R_X86_64_PC32:
+		case R_X86_64_PLT32:
+			val -= (u64)loc;
+			size = 4;
+			break;
+		case R_X86_64_PC64:
+			val -= (u64)loc;
+			size = 8;
+			break;
+		default:
+			pr_err("%s: Unknown rela relocation: %llu\n",
+			       me->name, ELF64_R_TYPE(rel[i].r_info));
+			return -ENOEXEC;
+		}
+
+		if (apply) {
+			if (memcmp(loc, &zero, size)) {
+				pr_err("x86/modules: 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;
+			}
+			write(loc, &val, size);
+		} else {
+			if (memcmp(loc, &val, size)) {
+				pr_warn("x86/modules: Invalid relocation target, existing value does not match expected value for type %d, loc %p, val %Lx\n",
+					(int)ELF64_R_TYPE(rel[i].r_info), loc, val);
+				return -ENOEXEC;
+			}
+			write(loc, &zero, size);
+		}
+	}
+	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;
+}
+
+static int write_relocate_add(Elf64_Shdr *sechdrs,
+			      const char *strtab,
+			      unsigned int symindex,
+			      unsigned int relsec,
+			      struct module *me,
+			      bool apply)
+{
+	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 = __write_relocate_add(sechdrs, strtab, symindex, relsec, me,
+				   write, apply);
+
+	if (!early) {
+		text_poke_sync();
+		mutex_unlock(&text_mutex);
+	}
+
+	return ret;
+}
+
+int apply_relocate_add(Elf64_Shdr *sechdrs,
+		   const char *strtab,
+		   unsigned int symindex,
+		   unsigned int relsec,
+		   struct module *me)
+{
+	return write_relocate_add(sechdrs, strtab, symindex, relsec, me, true);
+}
+
+#ifdef CONFIG_LIVEPATCH
+void clear_relocate_add(Elf64_Shdr *sechdrs,
+			const char *strtab,
+			unsigned int symindex,
+			unsigned int relsec,
+			struct module *me)
+{
+	write_relocate_add(sechdrs, strtab, symindex, relsec, me, false);
+}
+#endif
+
+#endif
+
+int module_finalize(const Elf_Ehdr *hdr,
+		    const Elf_Shdr *sechdrs,
+		    struct module *me)
+{
+	const Elf_Shdr *s, *alt = NULL, *locks = NULL,
+		*para = NULL, *orc = NULL, *orc_ip = NULL,
+		*retpolines = NULL, *returns = NULL, *ibt_endbr = NULL,
+		*calls = NULL, *cfi = NULL;
+	char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
+
+	for (s = sechdrs; s < sechdrs + hdr->e_shnum; 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(".call_sites", secstrings + s->sh_name))
+			calls = s;
+		if (!strcmp(".cfi_sites", secstrings + s->sh_name))
+			cfi = 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 || cfi) {
+		void *rseg = NULL, *cseg = NULL;
+		unsigned int rsize = 0, csize = 0;
+
+		if (retpolines) {
+			rseg = (void *)retpolines->sh_addr;
+			rsize = retpolines->sh_size;
+		}
+
+		if (cfi) {
+			cseg = (void *)cfi->sh_addr;
+			csize = cfi->sh_size;
+		}
+
+		apply_fineibt(rseg, rseg + rsize, cseg, cseg + csize);
+	}
+	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 (calls || para) {
+		struct callthunk_sites cs = {};
+
+		if (calls) {
+			cs.call_start = (void *)calls->sh_addr;
+			cs.call_end = (void *)calls->sh_addr + calls->sh_size;
+		}
+
+		if (para) {
+			cs.pv_start = (void *)para->sh_addr;
+			cs.pv_end = (void *)para->sh_addr + para->sh_size;
+		}
+
+		callthunks_patch_module_calls(&cs, me);
+	}
+	if (ibt_endbr) {
+		void *iseg = (void *)ibt_endbr->sh_addr;
+		apply_seal_endbr(iseg, iseg + ibt_endbr->sh_size);
+	}
+	if (locks) {
+		void *lseg = (void *)locks->sh_addr;
+		void *text = me->mem[MOD_TEXT].base;
+		void *text_end = text + me->mem[MOD_TEXT].size;
+		alternatives_smp_module_add(me, me->name,
+					    lseg, lseg + locks->sh_size,
+					    text, text_end);
+	}
+
+	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);
+}