Commit 0a939533 authored by Matthew Maurer's avatar Matthew Maurer Committed by Luis Chamberlain
Browse files

module: Factor out elf_validity_cache_index_str 



Pull out index validation for the symbol string section.

Note that this does not validate the *contents* of the string table,
only shape and presence of the section.

Signed-off-by: default avatarMatthew Maurer <mmaurer@google.com>
Reviewed-by: default avatarSami Tolvanen <samitolvanen@google.com>
Signed-off-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
parent 9bd4982c

kernel/module/main.c

+28 −9
Original line number Diff line number Diff line
@@ -2014,6 +2014,31 @@ static int elf_validity_cache_index_sym(struct load_info *info) 
	return 0;

}



/**

 * elf_validity_cache_index_str() - Validate and cache strtab index

 * @info: Load info to cache strtab index in.

 *        Must have &load_info->sechdrs and &load_info->secstrings populated.

 *        Must have &load_info->index.sym populated.

 *

 * Looks at the symbol table's associated string table, makes sure it is

 * in-bounds, and caches it.

 *

 * Return: %0 if valid, %-ENOEXEC on failure.

 */

static int elf_validity_cache_index_str(struct load_info *info)

{

	unsigned int str_idx = info->sechdrs[info->index.sym].sh_link;



	if (str_idx == SHN_UNDEF || str_idx >= info->hdr->e_shnum) {

		pr_err("Invalid ELF sh_link!=SHN_UNDEF(%d) or (sh_link(%d) >= hdr->e_shnum(%d)\n",

		       str_idx, str_idx, info->hdr->e_shnum);

		return -ENOEXEC;

	}



	info->index.str = str_idx;

	return 0;

}



/*

 * Check userspace passed ELF module against our expectations, and cache

 * useful variables for further processing as we go.
@@ -2037,7 +2062,6 @@ static int elf_validity_cache_index_sym(struct load_info *info) 
static int elf_validity_cache_copy(struct load_info *info, int flags)

{

	int err;

	int str_idx;



	err = elf_validity_cache_sechdrs(info);

	if (err < 0)
@@ -2054,16 +2078,11 @@ static int elf_validity_cache_copy(struct load_info *info, int flags) 
	err = elf_validity_cache_index_sym(info);

	if (err < 0)

		return err;



	str_idx = info->sechdrs[info->index.sym].sh_link;

	if (str_idx == SHN_UNDEF || str_idx >= info->hdr->e_shnum) {

		pr_err("Invalid ELF sh_link!=SHN_UNDEF(%d) or (sh_link(%d) >= hdr->e_shnum(%d)\n",

				str_idx, str_idx, info->hdr->e_shnum);

		return -ENOEXEC;

	}

	err = elf_validity_cache_index_str(info);

	if (err < 0)

		return err;



	/* Sets internal strings. */

	info->index.str = str_idx;

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



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