2016-04-12 06:51:21

by Libor Pechacek

Subject: [PATCH] module: Issue warnings when tainting kernel

While most of the locations where a kernel taint bit is set are accompanied
with a warning message, there are two which set their bits silently. If
the tainting module gets unloaded later on, it is almost impossible to tell
what was the reason for setting the flag.

Signed-off-by: Libor Pechacek <[email protected]>
---
kernel/module.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/module.c b/kernel/module.c
index 041200ca4a2d..e2d83d77a0e9 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2812,8 +2812,12 @@ static int check_modinfo(struct module *mod, struct load_info *info, int flags)
return -ENOEXEC;
}

- if (!get_modinfo(info, "intree"))
+ if (!get_modinfo(info, "intree")) {
+ if (!test_taint(TAINT_OOT_MODULE))
+ pr_warn("%s: loading out-of-tree module taints kernel.\n",
+ mod->name);
add_taint_module(mod, TAINT_OOT_MODULE, LOCKDEP_STILL_OK);
+ }

if (get_modinfo(info, "staging")) {
add_taint_module(mod, TAINT_CRAP, LOCKDEP_STILL_OK);
@@ -2978,6 +2982,8 @@ static int move_module(struct module *mod, struct load_info *info)

static int check_module_license_and_versions(struct module *mod)
{
+ int prev_taint = test_taint(TAINT_PROPRIETARY_MODULE);
+
/*
* ndiswrapper is under GPL by itself, but loads proprietary modules.
* Don't use add_taint_module(), as it would prevent ndiswrapper from
@@ -2996,6 +3002,9 @@ static int check_module_license_and_versions(struct module *mod)
add_taint_module(mod, TAINT_PROPRIETARY_MODULE,
LOCKDEP_NOW_UNRELIABLE);

+ if (!prev_taint && test_taint(TAINT_PROPRIETARY_MODULE))
+ pr_warn("%s: module license taints kernel.\n", mod->name);
+
#ifdef CONFIG_MODVERSIONS
if ((mod->num_syms && !mod->crcs)
|| (mod->num_gpl_syms && !mod->gpl_crcs)
--
1.7.12.4

2016-04-13 01:41:18

by Rusty Russell

Subject: Re: [PATCH] module: Issue warnings when tainting kernel

Libor Pechacek <[email protected]> writes:
> While most of the locations where a kernel taint bit is set are accompanied
> with a warning message, there are two which set their bits silently. If
> the tainting module gets unloaded later on, it is almost impossible to tell
> what was the reason for setting the flag.
>
> Signed-off-by: Libor Pechacek <[email protected]>

Applied, thanks!

Cheers,
Rusty.

> ---
> kernel/module.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/module.c b/kernel/module.c
> index 041200ca4a2d..e2d83d77a0e9 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -2812,8 +2812,12 @@ static int check_modinfo(struct module *mod, struct load_info *info, int flags)
> return -ENOEXEC;
> }
>
> - if (!get_modinfo(info, "intree"))
> + if (!get_modinfo(info, "intree")) {
> + if (!test_taint(TAINT_OOT_MODULE))
> + pr_warn("%s: loading out-of-tree module taints kernel.\n",
> + mod->name);
> add_taint_module(mod, TAINT_OOT_MODULE, LOCKDEP_STILL_OK);
> + }
>
> if (get_modinfo(info, "staging")) {
> add_taint_module(mod, TAINT_CRAP, LOCKDEP_STILL_OK);
> @@ -2978,6 +2982,8 @@ static int move_module(struct module *mod, struct load_info *info)
>
> static int check_module_license_and_versions(struct module *mod)
> {
> + int prev_taint = test_taint(TAINT_PROPRIETARY_MODULE);
> +
> /*
> * ndiswrapper is under GPL by itself, but loads proprietary modules.
> * Don't use add_taint_module(), as it would prevent ndiswrapper from
> @@ -2996,6 +3002,9 @@ static int check_module_license_and_versions(struct module *mod)
> add_taint_module(mod, TAINT_PROPRIETARY_MODULE,
> LOCKDEP_NOW_UNRELIABLE);
>
> + if (!prev_taint && test_taint(TAINT_PROPRIETARY_MODULE))
> + pr_warn("%s: module license taints kernel.\n", mod->name);
> +
> #ifdef CONFIG_MODVERSIONS
> if ((mod->num_syms && !mod->crcs)
> || (mod->num_gpl_syms && !mod->gpl_crcs)
> --
> 1.7.12.4