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Commit be7de5f9 authored by Prarit Bhargava's avatar Prarit Bhargava Committed by Rusty Russell
Browse files

modules: Add kernel parameter to blacklist modules 



Blacklisting a module in linux has long been a problem.  The current
procedure is to use rd.blacklist=module_name, however, that doesn't
cover the case after the initramfs and before a boot prompt (where one
is supposed to use /etc/modprobe.d/blacklist.conf to blacklist
runtime loading). Using rd.shell to get an early prompt is hit-or-miss,
and doesn't cover all situations AFAICT.

This patch adds this functionality of permanently blacklisting a module
by its name via the kernel parameter module_blacklist=module_name.

[v2]: Rusty, use core_param() instead of __setup() which simplifies
things.

[v3]: Rusty, undo wreckage from strsep()

[v4]: Rusty, simpler version of blacklisted()

Signed-off-by: default avatarPrarit Bhargava <prarit@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: linux-doc@vger.kernel.org
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 9502514f

Documentation/kernel-parameters.txt

+3 −0
Original line number Diff line number Diff line
@@ -2301,6 +2301,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 
			Note that if CONFIG_MODULE_SIG_FORCE is set, that

			is always true, so this option does nothing.



	module_blacklist=  [KNL] Do not load a comma-separated list of

			modules.  Useful for debugging problem modules.



	mousedev.tap_time=

			[MOUSE] Maximum time between finger touching and

			leaving touchpad surface for touch to be considered

kernel/module.c

+24 −0
Original line number Diff line number Diff line
@@ -3168,6 +3168,27 @@ int __weak module_frob_arch_sections(Elf_Ehdr *hdr, 
	return 0;

}



/* module_blacklist is a comma-separated list of module names */

static char *module_blacklist;

static bool blacklisted(char *module_name)

{

	const char *p;

	size_t len;



	if (!module_blacklist)

		return false;



	for (p = module_blacklist; *p; p += len) {

		len = strcspn(p, ",");

		if (strlen(module_name) == len && !memcmp(module_name, p, len))

			return true;

		if (p[len] == ',')

			len++;

	}

	return false;

}

core_param(module_blacklist, module_blacklist, charp, 0400);



static struct module *layout_and_allocate(struct load_info *info, int flags)

{

	/* Module within temporary copy. */
@@ -3178,6 +3199,9 @@ static struct module *layout_and_allocate(struct load_info *info, int flags) 
	if (IS_ERR(mod))

		return mod;



	if (blacklisted(mod->name))

		return ERR_PTR(-EPERM);



	err = check_modinfo(mod, info, flags);

	if (err)

		return ERR_PTR(err);