keys: Fix the use of the C++ keyword "private" in uapi/linux/keyctl.h

dhowells · James Morris · commit 2ecefa0a15fd · 2018-09-28T09:51:51.000-07:00
The keyctl_dh_params struct in uapi/linux/keyctl.h contains the symbol "private" which means that the header file will cause compilation failure if #included in to a C++ program. Further, the patch that added the same struct to the keyutils package named the symbol "priv", not "private". The previous attempt to fix this (commit 8a2336e) did so by simply renaming the kernel's copy of the field to dh_private, but this then breaks existing userspace and as such has been reverted (commit 8c0f9f5). [And note, to those who think that wrapping the struct in extern "C" {} will work: it won't; that only changes how symbol names are presented to the assembler and linker.]. Instead, insert an anonymous union around the "private" member and add a second member in there with the name "priv" to match the one in the keyutils package. The "private" member is then wrapped in !__cplusplus cpp-conditionals to hide it from C++. Fixes: ddbb411 ("KEYS: Add KEYCTL_DH_COMPUTE command") Fixes: 8a2336e ("uapi/linux/keyctl.h: don't use C++ reserved keyword as a struct member name") Signed-off-by: David Howells <dhowells@redhat.com> cc: Randy Dunlap <rdunlap@infradead.org> cc: Lubomir Rintel <lkundrak@v3.sk> cc: James Morris <jmorris@namei.org> cc: Mat Martineau <mathew.j.martineau@linux.intel.com> cc: Stephan Mueller <smueller@chronox.de> cc: Andrew Morton <akpm@linux-foundation.org> cc: Linus Torvalds <torvalds@linux-foundation.org> cc: stable@vger.kernel.org Signed-off-by: James Morris <james.morris@microsoft.com>
diff --git a/include/uapi/linux/keyctl.h b/include/uapi/linux/keyctl.h
@@ -65,7 +65,12 @@
 
 /* keyctl structures */
 struct keyctl_dh_params {
-	__s32 private;
+	union {
+#ifndef __cplusplus
+		__s32 private;
+#endif
+		__s32 priv;
+	};
 	__s32 prime;
 	__s32 base;
 };
