From be7de5f91fdc3a63ee01910c43f20db213445ce4 Mon Sep 17 00:00:00 2001 From: Prarit Bhargava Date: Thu, 21 Jul 2016 15:37:56 +0930 Subject: [PATCH] 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: Prarit Bhargava Cc: Jonathan Corbet Cc: Rusty Russell Cc: linux-doc@vger.kernel.org Signed-off-by: Rusty Russell --- Documentation/kernel-parameters.txt | 3 +++ kernel/module.c | 24 ++++++++++++++++++++++++ 2 files changed, 27 insertions(+) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 724970a25666..c59ae1af02b3 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -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 diff --git a/kernel/module.c b/kernel/module.c index beaebea627ff..c91c2fdca2e6 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -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); -- 2.20.1