From 35c739f7939ab7819025f77f167395c8c4937e48 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 1 Aug 2023 19:35:44 +0200 Subject: [PATCH] modules: only allow symbol_get of EXPORT_SYMBOL_GPL modules commit 9011e49d54dcc7653ebb8a1e05b5badb5ecfa9f9 upstream. 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 Reviewed-by: Greg Kroah-Hartman Signed-off-by: Luis Chamberlain Signed-off-by: Greg Kroah-Hartman --- kernel/module.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 2cd7de23cb1f..b9f582545b77 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2227,15 +2227,26 @@ static void free_module(struct module *mod) void *__symbol_get(const char *symbol) { struct module *owner; + enum mod_license license; const struct kernel_symbol *sym; preempt_disable(); - sym = find_symbol(symbol, &owner, NULL, NULL, true, true); - if (sym && strong_try_module_get(owner)) + sym = find_symbol(symbol, &owner, NULL, &license, true, true); + if (!sym) + goto fail; + if (license != GPL_ONLY) { + pr_warn("failing symbol_get of non-GPLONLY symbol %s.\n", + symbol); + goto fail; + } + if (strong_try_module_get(owner)) sym = NULL; preempt_enable(); return sym ? (void *)sym->value : NULL; +fail: + preempt_enable(); + return NULL; } EXPORT_SYMBOL_GPL(__symbol_get);