static int linker_sanity_check_elf_symtab()

in third/libbpf/src/linker.c [768:840]

• 67 lines of code
• 27 McCabe index (conditional complexity)

static int linker_sanity_check_elf_symtab(struct src_obj *obj, struct src_sec *sec)
{
	struct src_sec *link_sec;
	Elf64_Sym *sym;
	int i, n;

	if (sec->shdr->sh_entsize != sizeof(Elf64_Sym))
		return -EINVAL;
	if (sec->shdr->sh_size % sec->shdr->sh_entsize != 0)
		return -EINVAL;

	if (!sec->shdr->sh_link || sec->shdr->sh_link >= obj->sec_cnt) {
		pr_warn("ELF SYMTAB section #%zu points to missing STRTAB section #%zu in %s\n",
			sec->sec_idx, (size_t)sec->shdr->sh_link, obj->filename);
		return -EINVAL;
	}
	link_sec = &obj->secs[sec->shdr->sh_link];
	if (link_sec->shdr->sh_type != SHT_STRTAB) {
		pr_warn("ELF SYMTAB section #%zu points to invalid STRTAB section #%zu in %s\n",
			sec->sec_idx, (size_t)sec->shdr->sh_link, obj->filename);
		return -EINVAL;
	}

	n = sec->shdr->sh_size / sec->shdr->sh_entsize;
	sym = sec->data->d_buf;
	for (i = 0; i < n; i++, sym++) {
		int sym_type = ELF64_ST_TYPE(sym->st_info);
		int sym_bind = ELF64_ST_BIND(sym->st_info);
		int sym_vis = ELF64_ST_VISIBILITY(sym->st_other);

		if (i == 0) {
			if (sym->st_name != 0 || sym->st_info != 0
			    || sym->st_other != 0 || sym->st_shndx != 0
			    || sym->st_value != 0 || sym->st_size != 0) {
				pr_warn("ELF sym #0 is invalid in %s\n", obj->filename);
				return -EINVAL;
			}
			continue;
		}
		if (sym_bind != STB_LOCAL && sym_bind != STB_GLOBAL && sym_bind != STB_WEAK) {
			pr_warn("ELF sym #%d in section #%zu has unsupported symbol binding %d\n",
				i, sec->sec_idx, sym_bind);
			return -EINVAL;
		}
		if (sym_vis != STV_DEFAULT && sym_vis != STV_HIDDEN) {
			pr_warn("ELF sym #%d in section #%zu has unsupported symbol visibility %d\n",
				i, sec->sec_idx, sym_vis);
			return -EINVAL;
		}
		if (sym->st_shndx == 0) {
			if (sym_type != STT_NOTYPE || sym_bind == STB_LOCAL
			    || sym->st_value != 0 || sym->st_size != 0) {
				pr_warn("ELF sym #%d is invalid extern symbol in %s\n",
					i, obj->filename);

				return -EINVAL;
			}
			continue;
		}
		if (sym->st_shndx < SHN_LORESERVE && sym->st_shndx >= obj->sec_cnt) {
			pr_warn("ELF sym #%d in section #%zu points to missing section #%zu in %s\n",
				i, sec->sec_idx, (size_t)sym->st_shndx, obj->filename);
			return -EINVAL;
		}
		if (sym_type == STT_SECTION) {
			if (sym->st_value != 0)
				return -EINVAL;
			continue;
		}
	}

	return 0;
}