On Tue, Nov 09, 2021 at 05:45:45PM +0100, Ard Biesheuvel wrote:
quoted hunk ↗ jump to hunk
@@ -196,13 +190,21 @@ extern long __static_call_return0(void);
EXPORT_SYMBOL_GPL(STATIC_CALL_KEY(name)); \
EXPORT_SYMBOL_GPL(STATIC_CALL_TRAMP(name))
+#define EXPORT_STATIC_CALL_GETKEY_HELPER(name) \
+ struct static_call_key *STATIC_CALL_GETKEY(name)(void) { \
+ BUG_ON(!core_kernel_text( \
+ (unsigned long)__builtin_return_address(0))); \
+ return &STATIC_CALL_KEY(name); \
+ } \
+ EXPORT_SYMBOL_GPL(STATIC_CALL_GETKEY(name))
So if I were a nevarious module, I would look up the above symbol from
kallsyms (it is exported and easily obtainable) and then simply
read the text to discover the key address and we're in business.
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