linux/drivers/misc/lkdtm_rodata.c

/*
 * This includes functions that are meant to live entirely in .rodata
 * (via objcopy tricks), to validate the non-executability of .rodata.
 */
#include "lkdtm.h"

void notrace lkdtm_rodata_do_nothing(void)
{
	/* Does nothing. We just want an architecture agnostic "return". */
}
lkdtm: add function for testing .rodata section This adds a function that lives in the .rodata section. The section flags are corrected using objcopy since there is no way with gcc to declare section flags in an architecture-agnostic way. Signed-off-by: Kees Cook <keescook@chromium.org> 2016-02-22 14:09:29 -08:00			`/*`
			`* This includes functions that are meant to live entirely in .rodata`
			`* (via objcopy tricks), to validate the non-executability of .rodata.`
			`*/`
lkdtm: silence warnings about function declarations When building under W=1, the lack of lkdtm.h in lkdtm_usercopy.c and lkdtm_rodata.c was discovered. This fixes the issue and consolidates the common header and the pr_fmt macro for simplicity and regularity across each test source file. Signed-off-by: Kees Cook <keescook@chromium.org> 2016-07-15 16:04:39 -07:00			`#include "lkdtm.h"`
lkdtm: add function for testing .rodata section This adds a function that lives in the .rodata section. The section flags are corrected using objcopy since there is no way with gcc to declare section flags in an architecture-agnostic way. Signed-off-by: Kees Cook <keescook@chromium.org> 2016-02-22 14:09:29 -08:00
lkdtm: Mark lkdtm_rodata_do_nothing() notrace lkdtm_rodata_do_nothing() is an empty function which is generated in order to test the non-executability of rodata. Currently if function tracing is enabled then an mcount callsite will be generated for lkdtm_rodata_do_nothing(), and it will appear in the list of available functions for function tracing (available_filter_functions). Given it's purpose purely as a test function, it seems preferable for lkdtm_rodata_do_nothing() to be marked notrace, so it doesn't appear as traceable. This also avoids triggering a linker bug on powerpc: https://sourceware.org/bugzilla/show_bug.cgi?id=20428 When the linker sees code that needs to generate a call stub, eg. a branch to mcount(), it assumes the section is executable and dereferences a NULL pointer leading to a linker segfault. Marking lkdtm_rodata_do_nothing() notrace avoids triggering the bug because the function contains no other function calls. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 2016-08-05 14:25:53 -07:00			`void notrace lkdtm_rodata_do_nothing(void)`
lkdtm: add function for testing .rodata section This adds a function that lives in the .rodata section. The section flags are corrected using objcopy since there is no way with gcc to declare section flags in an architecture-agnostic way. Signed-off-by: Kees Cook <keescook@chromium.org> 2016-02-22 14:09:29 -08:00			`{`
			`/* Does nothing. We just want an architecture agnostic "return". */`
			`}`