Commit 5fdc7db6 authored by Jessica Yu's avatar Jessica Yu
Browse files

module: setup load info before module_sig_check() 



We want to be able to log the module name in early error messages, such as
when module signature verification fails.  Previously, the module name is
set in layout_and_allocate(), meaning that any error messages that happen
before (such as those in module_sig_check()) won't be logged with a module
name, which isn't terribly helpful.

In order to do this, reshuffle the order in load_module() and set up
load info earlier so that we can log the module name along with these
error messages. This requires splitting rewrite_section_headers() out of
setup_load_info().

While we're at it, clean up and split up the operations done in
layout_and_allocate(), setup_load_info(), and rewrite_section_headers()
more cleanly so these functions only perform what their names suggest.

Signed-off-by: default avatarJessica Yu <jeyu@kernel.org>
parent 81a0abd9

kernel/module.c

+43 −34
Original line number Diff line number Diff line
@@ -2488,7 +2488,11 @@ static char *get_modinfo(struct load_info *info, const char *tag) 
	Elf_Shdr *infosec = &info->sechdrs[info->index.info];

	unsigned long size = infosec->sh_size;



	for (p = (char *)infosec->sh_addr; p; p = next_string(p, &size)) {

	/*

	 * get_modinfo() calls made before rewrite_section_headers()

	 * must use sh_offset, as sh_addr isn't set!

	 */

	for (p = (char *)info->hdr + infosec->sh_offset; p; p = next_string(p, &size)) {

		if (strncmp(p, tag, taglen) == 0 && p[taglen] == '=')

			return p + taglen + 1;

	}
@@ -2928,17 +2932,7 @@ static int rewrite_section_headers(struct load_info *info, int flags) 
	}



	/* Track but don't keep modinfo and version sections. */

	if (flags & MODULE_INIT_IGNORE_MODVERSIONS)

		info->index.vers = 0; /* Pretend no __versions section! */

	else

		info->index.vers = find_sec(info, "__versions");

	info->sechdrs[info->index.vers].sh_flags &= ~(unsigned long)SHF_ALLOC;



	info->index.info = find_sec(info, ".modinfo");

	if (!info->index.info)

		info->name = "(missing .modinfo section)";

	else

		info->name = get_modinfo(info, "name");

	info->sechdrs[info->index.info].sh_flags &= ~(unsigned long)SHF_ALLOC;



	return 0;
@@ -2955,16 +2949,18 @@ static int rewrite_section_headers(struct load_info *info, int flags) 
static int setup_load_info(struct load_info *info, int flags)

{

	unsigned int i;

	int err;



	/* Set up the convenience variables */

	info->sechdrs = (void *)info->hdr + info->hdr->e_shoff;

	info->secstrings = (void *)info->hdr

		+ info->sechdrs[info->hdr->e_shstrndx].sh_offset;



	err = rewrite_section_headers(info, flags);

	if (err)

		return err;

	/* Try to find a name early so we can log errors with a module name */

	info->index.info = find_sec(info, ".modinfo");

	if (!info->index.info)

		info->name = "(missing .modinfo section)";

	else

		info->name = get_modinfo(info, "name");



	/* Find internal symbols and strings. */

	for (i = 1; i < info->hdr->e_shnum; i++) {
@@ -2977,6 +2973,11 @@ static int setup_load_info(struct load_info *info, int flags) 
		}

	}



	if (info->index.sym == 0) {

		pr_warn("%s: module has no symbols (stripped?)\n", info->name);

		return -ENOEXEC;

	}



	info->index.mod = find_sec(info, ".gnu.linkonce.this_module");

	if (!info->index.mod) {

		pr_warn("%s: No module found in object\n",
@@ -2984,26 +2985,22 @@ static int setup_load_info(struct load_info *info, int flags) 
		return -ENOEXEC;

	}

	/* This is temporary: point mod into copy of data. */

	info->mod = (void *)info->sechdrs[info->index.mod].sh_addr;

	info->mod = (void *)info->hdr + info->sechdrs[info->index.mod].sh_offset;



	/*

	 * If we didn't load the .modinfo 'name' field, fall back to

	 * If we didn't load the .modinfo 'name' field earlier, fall back to

	 * on-disk struct mod 'name' field.

	 */

	if (!info->name)

		info->name = info->mod->name;



	if (info->index.sym == 0) {

		pr_warn("%s: module has no symbols (stripped?)\n", info->name);

		return -ENOEXEC;

	}

	if (flags & MODULE_INIT_IGNORE_MODVERSIONS)

		info->index.vers = 0; /* Pretend no __versions section! */

	else

		info->index.vers = find_sec(info, "__versions");



	info->index.pcpu = find_pcpusec(info);



	/* Check module struct version now, before we try to use module. */

	if (!check_modstruct_version(info, info->mod))

		return -ENOEXEC;



	return 0;

}
@@ -3303,13 +3300,6 @@ static struct module *layout_and_allocate(struct load_info *info, int flags) 
	unsigned int ndx;

	int err;



	err = setup_load_info(info, flags);

	if (err)

		return ERR_PTR(err);



	if (blacklisted(info->name))

		return ERR_PTR(-EPERM);



	err = check_modinfo(info->mod, info, flags);

	if (err)

		return ERR_PTR(err);
@@ -3657,17 +3647,36 @@ static int load_module(struct load_info *info, const char __user *uargs, 
		       int flags)

{

	struct module *mod;

	long err;

	long err = 0;

	char *after_dashes;



	err = elf_header_check(info);

	if (err)

		goto free_copy;



	err = setup_load_info(info, flags);

	if (err)

		goto free_copy;



	if (blacklisted(info->name)) {

		err = -EPERM;

		goto free_copy;

	}



	err = module_sig_check(info, flags);

	if (err)

		goto free_copy;



	err = elf_header_check(info);

	err = rewrite_section_headers(info, flags);

	if (err)

		goto free_copy;



	/* Check module struct version now, before we try to use module. */

	if (!check_modstruct_version(info, info->mod)) {

		err = -ENOEXEC;

		goto free_copy;

	}



	/* Figure out module layout, and allocate all the memory. */

	mod = layout_and_allocate(info, flags);

	if (IS_ERR(mod)) {

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