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modules: Add kernel parameter to blacklist modules

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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: Prarit 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: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Prarit Bhargava 2016-07-21 15:37:56 +09:30 committed by Rusty Russell
parent 9502514f28
commit be7de5f91f
2 changed files with 27 additions and 0 deletions
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3
Documentation/kernel-parameters.txt
View File

@ -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

24
kernel/module.c
View File

@ -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);