Prarit Bhargava <prarit@xxxxxxxxxx> writes:
> 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(), and drop struct which
> simplifies things.
>
> Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx>
> Cc: Jonathan Corbet <corbet@xxxxxxx>
> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> Cc: linux-doc@xxxxxxxxxxxxxxx
> ---
> Documentation/kernel-parameters.txt | 3 +++
> kernel/module.c | 25 +++++++++++++++++++++++++
> 2 files changed, 28 insertions(+)
>
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 82b42c958d1c..c720b96f2efc 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -2295,6 +2295,9 @@ 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 5f71aa63ed2a..5ff5287b19a8 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -3155,6 +3155,28 @@ 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)
> +{
> + char *str, *entry;
> +
> + if (!module_blacklist)
> + return false;
> +
> + str = module_blacklist;
> + do {
> + entry = strsep(&str, ",");
> + if (!strcmp(module_name, entry)) {
> + pr_info("module %s is blacklisted\n", module_name);
> + return true;
> + }
strsep mangles the string; this will only work once :)
This is untested, and a little ugly:
len = strlen(module_name);
while ((p = strstr(p, module_name)) != NULL) {
if ((p == module_blacklist || p[-1] == ',') &&
(p[len] == ',' || p[len] == '\0'))
return true;
p += len;
}
return false;
Cheers,
Rusty.
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