Commit 1bb49db9 authored by Luis Chamberlain's avatar Luis Chamberlain
Browse files

module: move more elf validity checks to elf_validity_check() 



The symbol and strings section validation currently happen in
setup_load_info() but since they are also doing validity checks
move this to elf_validity_check().

Signed-off-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
parent c7ee8aeb

kernel/module/main.c

+44 −35
Original line number Diff line number Diff line
@@ -1658,6 +1658,8 @@ static int elf_validity_check(struct load_info *info) 
	Elf_Shdr *shdr, *strhdr;

	int err;

	unsigned int num_mod_secs = 0, mod_idx;

	unsigned int num_info_secs = 0, info_idx;

	unsigned int num_sym_secs = 0, sym_idx;



	if (info->len < sizeof(*(info->hdr))) {

		pr_err("Invalid ELF header len %lu\n", info->len);
@@ -1761,6 +1763,8 @@ static int elf_validity_check(struct load_info *info) 
				       info->hdr->e_shnum);

				goto no_exec;

			}

			num_sym_secs++;

			sym_idx = i;

			fallthrough;

		default:

			err = validate_section_offset(info, shdr);
@@ -1773,6 +1777,10 @@ static int elf_validity_check(struct load_info *info) 
				   ".gnu.linkonce.this_module") == 0) {

				num_mod_secs++;

				mod_idx = i;

			} else if (strcmp(info->secstrings + shdr->sh_name,

				   ".modinfo") == 0) {

				num_info_secs++;

				info_idx = i;

			}



			if (shdr->sh_flags & SHF_ALLOC) {
@@ -1786,6 +1794,27 @@ static int elf_validity_check(struct load_info *info) 
		}

	}



	if (num_info_secs > 1) {

		pr_err("Only one .modinfo section must exist.\n");

		goto no_exec;

	} else if (num_info_secs == 1) {

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

		info->index.info = info_idx;

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

	}



	if (num_sym_secs != 1) {

		pr_warn("%s: module has no symbols (stripped?)\n",

			info->name ?: "(missing .modinfo section or name field)");

		goto no_exec;

	}



	/* Sets internal symbols and strings. */

	info->index.sym = sym_idx;

	shdr = &info->sechdrs[sym_idx];

	info->index.str = shdr->sh_link;

	info->strtab = (char *)info->hdr + info->sechdrs[info->index.str].sh_offset;



	/*

	 * The ".gnu.linkonce.this_module" ELF section is special. It is

	 * what modpost uses to refer to __this_module and let's use rely
@@ -1802,7 +1831,8 @@ static int elf_validity_check(struct load_info *info) 
	 *     size

	 */

	if (num_mod_secs != 1) {

		pr_err("Only one .gnu.linkonce.this_module section must exist.\n");

		pr_err("module %s: Only one .gnu.linkonce.this_module section must exist.\n",

		       info->name ?: "(missing .modinfo section or name field)");

		goto no_exec;

	}
@@ -1813,17 +1843,20 @@ static int elf_validity_check(struct load_info *info) 
	 * pedantic about it.

	 */

	if (shdr->sh_type == SHT_NOBITS) {

		pr_err(".gnu.linkonce.this_module section must have a size set\n");

		pr_err("module %s: .gnu.linkonce.this_module section must have a size set\n",

		       info->name ?: "(missing .modinfo section or name field)");

		goto no_exec;

	}



	if (!(shdr->sh_flags & SHF_ALLOC)) {

		pr_err(".gnu.linkonce.this_module must occupy memory during process execution\n");

		pr_err("module %s: .gnu.linkonce.this_module must occupy memory during process execution\n",

		       info->name ?: "(missing .modinfo section or name field)");

		goto no_exec;

	}



	if (shdr->sh_size != sizeof(struct module)) {

		pr_err(".gnu.linkonce.this_module section size must match the kernel's built struct module size at run time\n");

		pr_err("module %s: .gnu.linkonce.this_module section size must match the kernel's built struct module size at run time\n",

		       info->name ?: "(missing .modinfo section or name field)");

		goto no_exec;

	}
@@ -1832,6 +1865,13 @@ static int elf_validity_check(struct load_info *info) 
	/* This is temporary: point mod into copy of data. */

	info->mod = (void *)info->hdr + shdr->sh_offset;



	/*

	 * 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;



	return 0;



no_exec:
@@ -1954,37 +1994,6 @@ 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;



	/* 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 = get_modinfo(info, "name");



	/* Find internal symbols and strings. */

	for (i = 1; i < info->hdr->e_shnum; i++) {

		if (info->sechdrs[i].sh_type == SHT_SYMTAB) {

			info->index.sym = i;

			info->index.str = info->sechdrs[i].sh_link;

			info->strtab = (char *)info->hdr

				+ info->sechdrs[info->index.str].sh_offset;

			break;

		}

	}



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

		pr_warn("%s: module has no symbols (stripped?)\n",

			info->name ?: "(missing .modinfo section or name field)");

		return -ENOEXEC;

	}



	/*

	 * 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 (flags & MODULE_INIT_IGNORE_MODVERSIONS)

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

	else