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modules: only allow symbol_get of EXPORT_SYMBOL_GPL modules

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It has recently come to my attention that nvidia is circumventing the
protection added in 262e6ae708 ("modules: inherit
TAINT_PROPRIETARY_MODULE") by importing exports from their proprietary
modules into an allegedly GPL licensed module and then rexporting them.

Given that symbol_get was only ever intended for tightly cooperating
modules using very internal symbols it is logical to restrict it to
being used on EXPORT_SYMBOL_GPL and prevent nvidia from costly DMCA
Circumvention of Access Controls law suites.

All symbols except for four used through symbol_get were already exported
as EXPORT_SYMBOL_GPL, and the remaining four ones were switched over in
the preparation patches.

Fixes: 262e6ae708 ("modules: inherit TAINT_PROPRIETARY_MODULE")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
This commit is contained in:
Christoph Hellwig 2023-08-01 19:35:44 +02:00 committed by Luis Chamberlain
parent 95e7ebc682
commit 9011e49d54
1 changed files with 11 additions and 3 deletions
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14
kernel/module/main.c
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@ -1295,12 +1295,20 @@ void *__symbol_get(const char *symbol)
};
preempt_disable();
if (!find_symbol(&fsa) || strong_try_module_get(fsa.owner)) {
preempt_enable();
return NULL;
if (!find_symbol(&fsa))
goto fail;
if (fsa.license != GPL_ONLY) {
pr_warn("failing symbol_get of non-GPLONLY symbol %s.\n",
symbol);
goto fail;
}
if (strong_try_module_get(fsa.owner))
goto fail;
preempt_enable();
return (void *)kernel_symbol_value(fsa.sym);
fail:
preempt_enable();
return NULL;
}
EXPORT_SYMBOL_GPL(__symbol_get);