Commit 9bd4982c authored by Matthew Maurer's avatar Matthew Maurer Committed by Luis Chamberlain
Browse files

module: Factor out elf_validity_cache_index_sym 



Centralize symbol table detection and property validation.

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 0be41a93

kernel/module/main.c

+44 −29
Original line number Diff line number Diff line
@@ -1980,6 +1980,39 @@ static int elf_validity_cache_index_mod(struct load_info *info) 
	return 0;

}



/**

 * elf_validity_cache_index_sym() - Validate and cache symtab index

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

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

 *

 * Checks that there is exactly one symbol table, then caches its index in

 * &load_info->index.sym.

 *

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

 */

static int elf_validity_cache_index_sym(struct load_info *info)

{

	unsigned int sym_idx;

	unsigned int num_sym_secs = 0;

	int i;



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

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

			num_sym_secs++;

			sym_idx = i;

		}

	}



	if (num_sym_secs != 1) {

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

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

		return -ENOEXEC;

	}



	info->index.sym = sym_idx;



	return 0;

}



/*

 * Check userspace passed ELF module against our expectations, and cache
@@ -2003,10 +2036,8 @@ static int elf_validity_cache_index_mod(struct load_info *info) 
 */

static int elf_validity_cache_copy(struct load_info *info, int flags)

{

	unsigned int i;

	Elf_Shdr *shdr;

	int err;

	unsigned int num_sym_secs = 0, sym_idx;

	int str_idx;



	err = elf_validity_cache_sechdrs(info);

	if (err < 0)
@@ -2018,34 +2049,21 @@ static int elf_validity_cache_copy(struct load_info *info, int flags) 
	if (err < 0)

		return err;

	err = elf_validity_cache_index_mod(info);

	if (err < 0)

		return err;

	err = elf_validity_cache_index_sym(info);

	if (err < 0)

		return err;



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

		shdr = &info->sechdrs[i];

		if (shdr->sh_type == SHT_SYMTAB) {

			if (shdr->sh_link == SHN_UNDEF

			    || shdr->sh_link >= info->hdr->e_shnum) {

	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",

				       shdr->sh_link, shdr->sh_link,

				       info->hdr->e_shnum);

				goto no_exec;

			}

			num_sym_secs++;

			sym_idx = i;

		}

	}



	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;

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

		return -ENOEXEC;

	}



	/* Sets internal symbols and strings. */

	info->index.sym = sym_idx;

	shdr = &info->sechdrs[sym_idx];

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

	/* 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. */
@@ -2066,9 +2084,6 @@ static int elf_validity_cache_copy(struct load_info *info, int flags) 
	info->index.pcpu = find_pcpusec(info);



	return 0;



no_exec:

	return -ENOEXEC;

}



#define COPY_CHUNK_SIZE (16*PAGE_SIZE)