module.c

linux 2.6.19 kernel source code before patching

	if (sym->st_shndx == SHN_UNDEF)
		return 'U';
	if (sym->st_shndx == SHN_ABS)
		return 'a';
	if (sym->st_shndx >= SHN_LORESERVE)
		return '?';
	if (sechdrs[sym->st_shndx].sh_flags & SHF_EXECINSTR)
		return 't';
	if (sechdrs[sym->st_shndx].sh_flags & SHF_ALLOC
	    && sechdrs[sym->st_shndx].sh_type != SHT_NOBITS) {
		if (!(sechdrs[sym->st_shndx].sh_flags & SHF_WRITE))
			return 'r';
		else if (sechdrs[sym->st_shndx].sh_flags & ARCH_SHF_SMALL)
			return 'g';
		else
			return 'd';
	}
	if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) {
		if (sechdrs[sym->st_shndx].sh_flags & ARCH_SHF_SMALL)
			return 's';
		else
			return 'b';
	}
	if (strncmp(secstrings + sechdrs[sym->st_shndx].sh_name,
		    ".debug", strlen(".debug")) == 0)
		return 'n';
	return '?';
}

static void add_kallsyms(struct module *mod,
			 Elf_Shdr *sechdrs,
			 unsigned int symindex,
			 unsigned int strindex,
			 const char *secstrings)
{
	unsigned int i;

	mod->symtab = (void *)sechdrs[symindex].sh_addr;
	mod->num_symtab = sechdrs[symindex].sh_size / sizeof(Elf_Sym);
	mod->strtab = (void *)sechdrs[strindex].sh_addr;

	/* Set types up while we still have access to sections. */
	for (i = 0; i < mod->num_symtab; i++)
		mod->symtab[i].st_info
			= elf_type(&mod->symtab[i], sechdrs, secstrings, mod);
}
#else
static inline void add_kallsyms(struct module *mod,
				Elf_Shdr *sechdrs,
				unsigned int symindex,
				unsigned int strindex,
				const char *secstrings)
{
}
#endif /* CONFIG_KALLSYMS */

/* Allocate and load the module: note that size of section 0 is always
   zero, and we rely on this for optional sections. */
static struct module *load_module(void __user *umod,
				  unsigned long len,
				  const char __user *uargs)
{
	Elf_Ehdr *hdr;
	Elf_Shdr *sechdrs;
	char *secstrings, *args, *modmagic, *strtab = NULL;
	unsigned int i;
	unsigned int symindex = 0;
	unsigned int strindex = 0;
	unsigned int setupindex;
	unsigned int exindex;
	unsigned int exportindex;
	unsigned int modindex;
	unsigned int obsparmindex;
	unsigned int infoindex;
	unsigned int gplindex;
	unsigned int crcindex;
	unsigned int gplcrcindex;
	unsigned int versindex;
	unsigned int pcpuindex;
	unsigned int gplfutureindex;
	unsigned int gplfuturecrcindex;
	unsigned int unwindex = 0;
	unsigned int unusedindex;
	unsigned int unusedcrcindex;
	unsigned int unusedgplindex;
	unsigned int unusedgplcrcindex;
	struct module *mod;
	long err = 0;
	void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */
	struct exception_table_entry *extable;
	mm_segment_t old_fs;

	DEBUGP("load_module: umod=%p, len=%lu, uargs=%p\n",
	       umod, len, uargs);
	if (len < sizeof(*hdr))
		return ERR_PTR(-ENOEXEC);

	/* Suck in entire file: we'll want most of it. */
	/* vmalloc barfs on "unusual" numbers.  Check here */
	if (len > 64 * 1024 * 1024 || (hdr = vmalloc(len)) == NULL)
		return ERR_PTR(-ENOMEM);
	if (copy_from_user(hdr, umod, len) != 0) {
		err = -EFAULT;
		goto free_hdr;
	}

	/* Sanity checks against insmoding binaries or wrong arch,
           weird elf version */
	if (memcmp(hdr->e_ident, ELFMAG, 4) != 0
	    || hdr->e_type != ET_REL
	    || !elf_check_arch(hdr)
	    || hdr->e_shentsize != sizeof(*sechdrs)) {
		err = -ENOEXEC;
		goto free_hdr;
	}

	if (len < hdr->e_shoff + hdr->e_shnum * sizeof(Elf_Shdr))
		goto truncated;

	/* Convenience variables */
	sechdrs = (void *)hdr + hdr->e_shoff;
	secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
	sechdrs[0].sh_addr = 0;

	for (i = 1; i < hdr->e_shnum; i++) {
		if (sechdrs[i].sh_type != SHT_NOBITS
		    && len < sechdrs[i].sh_offset + sechdrs[i].sh_size)
			goto truncated;

		/* Mark all sections sh_addr with their address in the
		   temporary image. */
		sechdrs[i].sh_addr = (size_t)hdr + sechdrs[i].sh_offset;

		/* Internal symbols and strings. */
		if (sechdrs[i].sh_type == SHT_SYMTAB) {
			symindex = i;
			strindex = sechdrs[i].sh_link;
			strtab = (char *)hdr + sechdrs[strindex].sh_offset;
		}
#ifndef CONFIG_MODULE_UNLOAD
		/* Don't load .exit sections */
		if (strncmp(secstrings+sechdrs[i].sh_name, ".exit", 5) == 0)
			sechdrs[i].sh_flags &= ~(unsigned long)SHF_ALLOC;
#endif
	}

	modindex = find_sec(hdr, sechdrs, secstrings,
			    ".gnu.linkonce.this_module");
	if (!modindex) {
		printk(KERN_WARNING "No module found in object\n");
		err = -ENOEXEC;
		goto free_hdr;
	}
	mod = (void *)sechdrs[modindex].sh_addr;

	if (symindex == 0) {
		printk(KERN_WARNING "%s: module has no symbols (stripped?)\n",
		       mod->name);
		err = -ENOEXEC;
		goto free_hdr;
	}

	/* Optional sections */
	exportindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab");
	gplindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab_gpl");
	gplfutureindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab_gpl_future");
	unusedindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab_unused");
	unusedgplindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab_unused_gpl");
	crcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab");
	gplcrcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab_gpl");
	gplfuturecrcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab_gpl_future");
	unusedcrcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab_unused");
	unusedgplcrcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab_unused_gpl");
	setupindex = find_sec(hdr, sechdrs, secstrings, "__param");
	exindex = find_sec(hdr, sechdrs, secstrings, "__ex_table");
	obsparmindex = find_sec(hdr, sechdrs, secstrings, "__obsparm");
	versindex = find_sec(hdr, sechdrs, secstrings, "__versions");
	infoindex = find_sec(hdr, sechdrs, secstrings, ".modinfo");
	pcpuindex = find_pcpusec(hdr, sechdrs, secstrings);
#ifdef ARCH_UNWIND_SECTION_NAME
	unwindex = find_sec(hdr, sechdrs, secstrings, ARCH_UNWIND_SECTION_NAME);
#endif

	/* Don't keep modinfo section */
	sechdrs[infoindex].sh_flags &= ~(unsigned long)SHF_ALLOC;
#ifdef CONFIG_KALLSYMS
	/* Keep symbol and string tables for decoding later. */
	sechdrs[symindex].sh_flags |= SHF_ALLOC;
	sechdrs[strindex].sh_flags |= SHF_ALLOC;
#endif
	if (unwindex)
		sechdrs[unwindex].sh_flags |= SHF_ALLOC;

	/* Check module struct version now, before we try to use module. */
	if (!check_modstruct_version(sechdrs, versindex, mod)) {
		err = -ENOEXEC;
		goto free_hdr;
	}

	modmagic = get_modinfo(sechdrs, infoindex, "vermagic");
	/* This is allowed: modprobe --force will invalidate it. */
	if (!modmagic) {
		add_taint_module(mod, TAINT_FORCED_MODULE);
		printk(KERN_WARNING "%s: no version magic, tainting kernel.\n",
		       mod->name);
	} else if (!same_magic(modmagic, vermagic)) {
		printk(KERN_ERR "%s: version magic '%s' should be '%s'\n",
		       mod->name, modmagic, vermagic);
		err = -ENOEXEC;
		goto free_hdr;
	}

	/* Now copy in args */
	args = strndup_user(uargs, ~0UL >> 1);
	if (IS_ERR(args)) {
		err = PTR_ERR(args);
		goto free_hdr;
	}

	if (find_module(mod->name)) {
		err = -EEXIST;
		goto free_mod;
	}

	mod->state = MODULE_STATE_COMING;

	/* Allow arches to frob section contents and sizes.  */
	err = module_frob_arch_sections(hdr, sechdrs, secstrings, mod);
	if (err < 0)
		goto free_mod;

	if (pcpuindex) {
		/* We have a special allocation for this section. */
		percpu = percpu_modalloc(sechdrs[pcpuindex].sh_size,
					 sechdrs[pcpuindex].sh_addralign,
					 mod->name);
		if (!percpu) {
			err = -ENOMEM;
			goto free_mod;
		}
		sechdrs[pcpuindex].sh_flags &= ~(unsigned long)SHF_ALLOC;
		mod->percpu = percpu;
	}

	/* Determine total sizes, and put offsets in sh_entsize.  For now
	   this is done generically; there doesn't appear to be any
	   special cases for the architectures. */
	layout_sections(mod, hdr, sechdrs, secstrings);

	/* Do the allocs. */
	ptr = module_alloc(mod->core_size);
	if (!ptr) {
		err = -ENOMEM;
		goto free_percpu;
	}
	memset(ptr, 0, mod->core_size);
	mod->module_core = ptr;

	ptr = module_alloc(mod->init_size);
	if (!ptr && mod->init_size) {
		err = -ENOMEM;
		goto free_core;
	}
	memset(ptr, 0, mod->init_size);
	mod->module_init = ptr;

	/* Transfer each section which specifies SHF_ALLOC */
	DEBUGP("final section addresses:\n");
	for (i = 0; i < hdr->e_shnum; i++) {
		void *dest;

		if (!(sechdrs[i].sh_flags & SHF_ALLOC))
			continue;

		if (sechdrs[i].sh_entsize & INIT_OFFSET_MASK)
			dest = mod->module_init
				+ (sechdrs[i].sh_entsize & ~INIT_OFFSET_MASK);
		else
			dest = mod->module_core + sechdrs[i].sh_entsize;

		if (sechdrs[i].sh_type != SHT_NOBITS)
			memcpy(dest, (void *)sechdrs[i].sh_addr,
			       sechdrs[i].sh_size);
		/* Update sh_addr to point to copy in image. */
		sechdrs[i].sh_addr = (unsigned long)dest;
		DEBUGP("\t0x%lx %s\n", sechdrs[i].sh_addr, secstrings + sechdrs[i].sh_name);
	}
	/* Module has been moved. */
	mod = (void *)sechdrs[modindex].sh_addr;

	/* Now we've moved module, initialize linked lists, etc. */
	module_unload_init(mod);

	/* Initialize kobject, so we can reference it. */
	if (mod_sysfs_init(mod) != 0)
		goto cleanup;

	/* Set up license info based on the info section */
	set_license(mod, get_modinfo(sechdrs, infoindex, "license"));

	if (strcmp(mod->name, "ndiswrapper") == 0)
		add_taint(TAINT_PROPRIETARY_MODULE);
	if (strcmp(mod->name, "driverloader") == 0)
		add_taint_module(mod, TAINT_PROPRIETARY_MODULE);

	/* Set up MODINFO_ATTR fields */
	setup_modinfo(mod, sechdrs, infoindex);

	/* Fix up syms, so that st_value is a pointer to location. */
	err = simplify_symbols(sechdrs, symindex, strtab, versindex, pcpuindex,
			       mod);
	if (err < 0)
		goto cleanup;

	/* Set up EXPORTed & EXPORT_GPLed symbols (section 0 is 0 length) */
	mod->num_syms = sechdrs[exportindex].sh_size / sizeof(*mod->syms);
	mod->syms = (void *)sechdrs[exportindex].sh_addr;
	if (crcindex)
		mod->crcs = (void *)sechdrs[crcindex].sh_addr;
	mod->num_gpl_syms = sechdrs[gplindex].sh_size / sizeof(*mod->gpl_syms);
	mod->gpl_syms = (void *)sechdrs[gplindex].sh_addr;
	if (gplcrcindex)
		mod->gpl_crcs = (void *)sechdrs[gplcrcindex].sh_addr;
	mod->num_gpl_future_syms = sechdrs[gplfutureindex].sh_size /
					sizeof(*mod->gpl_future_syms);
	mod->num_unused_syms = sechdrs[unusedindex].sh_size /
					sizeof(*mod->unused_syms);
	mod->num_unused_gpl_syms = sechdrs[unusedgplindex].sh_size /
					sizeof(*mod->unused_gpl_syms);
	mod->gpl_future_syms = (void *)sechdrs[gplfutureindex].sh_addr;
	if (gplfuturecrcindex)
		mod->gpl_future_crcs = (void *)sechdrs[gplfuturecrcindex].sh_addr;

	mod->unused_syms = (void *)sechdrs[unusedindex].sh_addr;
	if (unusedcrcindex)
		mod->unused_crcs = (void *)sechdrs[unusedcrcindex].sh_addr;
	mod->unused_gpl_syms = (void *)sechdrs[unusedgplindex].sh_addr;
	if (unusedgplcrcindex)
		mod->unused_crcs = (void *)sechdrs[unusedgplcrcindex].sh_addr;

#ifdef CONFIG_MODVERSIONS
	if ((mod->num_syms && !crcindex) || 
	    (mod->num_gpl_syms && !gplcrcindex) ||
	    (mod->num_gpl_future_syms && !gplfuturecrcindex) ||
	    (mod->num_unused_syms && !unusedcrcindex) ||
	    (mod->num_unused_gpl_syms && !unusedgplcrcindex)) {
		printk(KERN_WARNING "%s: No versions for exported symbols."
		       " Tainting kernel.\n", mod->name);
		add_taint_module(mod, TAINT_FORCED_MODULE);
	}
#endif

	/* Now do relocations. */
	for (i = 1; i < hdr->e_shnum; i++) {
		const char *strtab = (char *)sechdrs[strindex].sh_addr;
		unsigned int info = sechdrs[i].sh_info;

		/* Not a valid relocation section? */
		if (info >= hdr->e_shnum)
			continue;

		/* Don't bother with non-allocated sections */
		if (!(sechdrs[info].sh_flags & SHF_ALLOC))
			continue;

		if (sechdrs[i].sh_type == SHT_REL)
			err = apply_relocate(sechdrs, strtab, symindex, i,mod);
		else if (sechdrs[i].sh_type == SHT_RELA)
			err = apply_relocate_add(sechdrs, strtab, symindex, i,
						 mod);
		if (err < 0)
			goto cleanup;
	}

        /* Find duplicate symbols */
	err = verify_export_symbols(mod);

	if (err < 0)
		goto cleanup;

  	/* Set up and sort exception table */
	mod->num_exentries = sechdrs[exindex].sh_size / sizeof(*mod->extable);
	mod->extable = extable = (void *)sechdrs[exindex].sh_addr;
	sort_extable(extable, extable + mod->num_exentries);

	/* Finally, copy percpu area over. */
	percpu_modcopy(mod->percpu, (void *)sechdrs[pcpuindex].sh_addr,
		       sechdrs[pcpuindex].sh_size);

	add_kallsyms(mod, sechdrs, symindex, strindex, secstrings);

	err = module_finalize(hdr, sechdrs, mod);
	if (err < 0)
		goto cleanup;

	/* flush the icache in correct context */
	old_fs = get_fs();
	set_fs(KERNEL_DS);

	/*
	 * Flush the instruction cache, since we've played with text.
	 * Do it before processing of module parameters, so the module
	 * can provide parameter accessor functions of its own.
	 */
	if (mod->module_init)
		flush_icache_range((unsigned long)mod->module_init,
				   (unsigned long)mod->module_init
				   + mod->init_size);
	flush_icache_range((unsigned long)mod->module_core,
			   (unsigned long)mod->module_core + mod->core_size);

	set_fs(old_fs);

	mod->args = args;
	if (obsparmindex)
		printk(KERN_WARNING "%s: Ignoring obsolete parameters\n",
		       mod->name);

	/* Size of section 0 is 0, so this works well if no params */
	err = parse_args(mod->name, mod->args,
			 (struct kernel_param *)
			 sechdrs[setupindex].sh_addr,
			 sechdrs[setupindex].sh_size
			 / sizeof(struct kernel_param),
			 NULL);
	if (err < 0)
		goto arch_cleanup;

	err = mod_sysfs_setup(mod, 
			      (struct kernel_param *)
			      sechdrs[setupindex].sh_addr,
			      sechdrs[setupindex].sh_size
			      / sizeof(struct kernel_param));
	if (err < 0)
		goto arch_cleanup;
	add_sect_attrs(mod, hdr->e_shnum, secstrings, sechdrs);

	/* Size of section 0 is 0, so this works well if no unwind info. */
	mod->unwind_info = unwind_add_table(mod,
	                                    (void *)sechdrs[unwindex].sh_addr,
	                                    sechdrs[unwindex].sh_size);

	/* Get rid of temporary copy */
	vfree(hdr);

	/* Done! */
	return mod;

 arch_cleanup:
	module_arch_cleanup(mod);
 cleanup:
	module_unload_free(mod);
	module_free(mod, mod->module_init);
 free_core:
	module_free(mod, mod->module_core);
 free_percpu:
	if (percpu)
		percpu_modfree(percpu);
 free_mod:
	kfree(args);
 free_hdr:
	vfree(hdr);
	return ERR_PTR(err);

 truncated:
	printk(KERN_ERR "Module len %lu truncated\n", len);
	err = -ENOEXEC;
	goto free_hdr;
}

/*
 * link the module with the whole machine is stopped with interrupts off
 * - this defends against kallsyms not taking locks
 */
static int __link_module(void *_mod)
{
	struct module *mod = _mod;
	list_add(&mod->list, &modules);
	return 0;
}

/* This is where the real work happens */
asmlinkage long
sys_init_module(void __user *umod,
		unsigned long len,
		const char __user *uargs)
{
	struct module *mod;
	int ret = 0;

	/* Must have permission */
	if (!capable(CAP_SYS_MODULE))
		return -EPERM;

	/* Only one module load at a time, please */
	if (mutex_lock_interruptible(&module_mutex) != 0)
		return -EINTR;

	/* Do all the hard work */