Commit 6ab9942c authored by Christophe Leroy's avatar Christophe Leroy Committed by Luis Chamberlain
Browse files

module: Introduce data_layout 



In order to allow separation of data from text, add another layout,
called data_layout. For architectures requesting separation of text
and data, only text will go in core_layout and data will go in
data_layout.

For architectures which keep text and data together, make data_layout
an alias of core_layout, that way data_layout can be used for all
data manipulations, regardless of whether data is in core_layout or
data_layout.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
parent 446d5566

kernel/module/internal.h

+2 −0
Original line number Diff line number Diff line
@@ -20,6 +20,8 @@ 
/* Maximum number of characters written by module_flags() */

#define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4)



#define	data_layout core_layout



/*

 * Modules' sections will be aligned on page boundaries

 * to ensure complete separation of code and data, but

kernel/module/kallsyms.c

+9 −9
Original line number Diff line number Diff line
@@ -134,12 +134,12 @@ void layout_symtab(struct module *mod, struct load_info *info) 
	}



	/* Append room for core symbols at end of core part. */

	info->symoffs = ALIGN(mod->core_layout.size, symsect->sh_addralign ?: 1);

	info->stroffs = mod->core_layout.size = info->symoffs + ndst * sizeof(Elf_Sym);

	mod->core_layout.size += strtab_size;

	info->core_typeoffs = mod->core_layout.size;

	mod->core_layout.size += ndst * sizeof(char);

	mod->core_layout.size = strict_align(mod->core_layout.size);

	info->symoffs = ALIGN(mod->data_layout.size, symsect->sh_addralign ?: 1);

	info->stroffs = mod->data_layout.size = info->symoffs + ndst * sizeof(Elf_Sym);

	mod->data_layout.size += strtab_size;

	info->core_typeoffs = mod->data_layout.size;

	mod->data_layout.size += ndst * sizeof(char);

	mod->data_layout.size = strict_align(mod->data_layout.size);



	/* Put string table section at end of init part of module. */

	strsect->sh_flags |= SHF_ALLOC;
@@ -187,9 +187,9 @@ void add_kallsyms(struct module *mod, const struct load_info *info) 
	 * Now populate the cut down core kallsyms for after init

	 * and set types up while we still have access to sections.

	 */

	mod->core_kallsyms.symtab = dst = mod->core_layout.base + info->symoffs;

	mod->core_kallsyms.strtab = s = mod->core_layout.base + info->stroffs;

	mod->core_kallsyms.typetab = mod->core_layout.base + info->core_typeoffs;

	mod->core_kallsyms.symtab = dst = mod->data_layout.base + info->symoffs;

	mod->core_kallsyms.strtab = s = mod->data_layout.base + info->stroffs;

	mod->core_kallsyms.typetab = mod->data_layout.base + info->core_typeoffs;

	src = rcu_dereference_sched(mod->kallsyms)->symtab;

	for (ndst = i = 0; i < rcu_dereference_sched(mod->kallsyms)->num_symtab; i++) {

		rcu_dereference_sched(mod->kallsyms)->typetab[i] = elf_type(src + i, info);

kernel/module/main.c

+12 −8
Original line number Diff line number Diff line
@@ -1190,7 +1190,7 @@ static void free_module(struct module *mod) 
	percpu_modfree(mod);



	/* Free lock-classes; relies on the preceding sync_rcu(). */

	lockdep_free_key_range(mod->core_layout.base, mod->core_layout.size);

	lockdep_free_key_range(mod->data_layout.base, mod->data_layout.size);



	/* Finally, free the core (containing the module structure) */

	module_memfree(mod->core_layout.base);
@@ -1431,13 +1431,15 @@ static void layout_sections(struct module *mod, struct load_info *info) 
		for (i = 0; i < info->hdr->e_shnum; ++i) {

			Elf_Shdr *s = &info->sechdrs[i];

			const char *sname = info->secstrings + s->sh_name;

			unsigned int *sizep;



			if ((s->sh_flags & masks[m][0]) != masks[m][0]

			    || (s->sh_flags & masks[m][1])

			    || s->sh_entsize != ~0UL

			    || module_init_layout_section(sname))

				continue;

			s->sh_entsize = module_get_offset(mod, &mod->core_layout.size, s, i);

			sizep = m ? &mod->data_layout.size : &mod->core_layout.size;

			s->sh_entsize = module_get_offset(mod, sizep, s, i);

			pr_debug("\t%s\n", sname);

		}

		switch (m) {
@@ -1446,15 +1448,15 @@ static void layout_sections(struct module *mod, struct load_info *info) 
			mod->core_layout.text_size = mod->core_layout.size;

			break;

		case 1: /* RO: text and ro-data */

			mod->core_layout.size = strict_align(mod->core_layout.size);

			mod->core_layout.ro_size = mod->core_layout.size;

			mod->data_layout.size = strict_align(mod->data_layout.size);

			mod->data_layout.ro_size = mod->data_layout.size;

			break;

		case 2: /* RO after init */

			mod->core_layout.size = strict_align(mod->core_layout.size);

			mod->core_layout.ro_after_init_size = mod->core_layout.size;

			mod->data_layout.size = strict_align(mod->data_layout.size);

			mod->data_layout.ro_after_init_size = mod->data_layout.size;

			break;

		case 4: /* whole core */

			mod->core_layout.size = strict_align(mod->core_layout.size);

			mod->data_layout.size = strict_align(mod->data_layout.size);

			break;

		}

	}
@@ -2134,6 +2136,8 @@ static int move_module(struct module *mod, struct load_info *info) 
		if (shdr->sh_entsize & INIT_OFFSET_MASK)

			dest = mod->init_layout.base

				+ (shdr->sh_entsize & ~INIT_OFFSET_MASK);

		else if (!(shdr->sh_flags & SHF_EXECINSTR))

			dest = mod->data_layout.base + shdr->sh_entsize;

		else

			dest = mod->core_layout.base + shdr->sh_entsize;
@@ -2829,7 +2833,7 @@ static int load_module(struct load_info *info, const char __user *uargs, 
	mutex_unlock(&module_mutex);

 free_module:

	/* Free lock-classes; relies on the preceding sync_rcu() */

	lockdep_free_key_range(mod->core_layout.base, mod->core_layout.size);

	lockdep_free_key_range(mod->data_layout.base, mod->data_layout.size);



	module_deallocate(mod, info);

 free_copy:

kernel/module/strict_rwx.c

+5 −5
Original line number Diff line number Diff line
@@ -101,12 +101,12 @@ void module_enable_ro(const struct module *mod, bool after_init) 
	set_vm_flush_reset_perms(mod->init_layout.base);

	frob_text(&mod->core_layout, set_memory_ro);



	frob_rodata(&mod->core_layout, set_memory_ro);

	frob_rodata(&mod->data_layout, set_memory_ro);

	frob_text(&mod->init_layout, set_memory_ro);

	frob_rodata(&mod->init_layout, set_memory_ro);



	if (after_init)

		frob_ro_after_init(&mod->core_layout, set_memory_ro);

		frob_ro_after_init(&mod->data_layout, set_memory_ro);

}



void module_enable_nx(const struct module *mod)
@@ -114,9 +114,9 @@ void module_enable_nx(const struct module *mod) 
	if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))

		return;



	frob_rodata(&mod->core_layout, set_memory_nx);

	frob_ro_after_init(&mod->core_layout, set_memory_nx);

	frob_writable_data(&mod->core_layout, set_memory_nx);

	frob_rodata(&mod->data_layout, set_memory_nx);

	frob_ro_after_init(&mod->data_layout, set_memory_nx);

	frob_writable_data(&mod->data_layout, set_memory_nx);

	frob_rodata(&mod->init_layout, set_memory_nx);

	frob_writable_data(&mod->init_layout, set_memory_nx);

}