Messages in this thread Patch in this message | | | From | Christoph Hellwig <> | Subject | [PATCH 5/5] modules: only allow symbol_get of EXPORT_SYMBOL_GPL modules | Date | Tue, 1 Aug 2023 19:35:44 +0200 |
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It has recently come to my attention that nvidia is circumventing the protection added in 262e6ae7081d ("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: 262e6ae7081d ("modules: inherit TAINT_PROPRIETARY_MODULE") Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- kernel/module/main.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/kernel/module/main.c b/kernel/module/main.c index 59b1d067e52890..c395af9eced114 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -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); -- 2.39.2
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