[RFC PATCH v2 01/14] lsm: Only build lsm_audit.c if CONFIG_AUDIT is set

[Guenter Roeck]

On Tue, Oct 22, 2024 at 06:09:56PM +0200, Mickaël Salaün wrote:
> When CONFIG_AUDIT is set, its CONFIG_NET dependency is also set, and the
> dev_get_by_index and init_net symbols (used by dump_common_audit_data)
> are found by the linker.  dump_common_audit_data() should then failed to
> build when CONFIG_NET is not set. However, because the compiler is
> smart, it knows that audit_log_start() always return NULL when
> !CONFIG_AUDIT, and it doesn't build the body of common_lsm_audit().  As
> a side effect, dump_common_audit_data() is not built and the linker
> doesn't error out because of missing symbols.
> 
> Let's only build lsm_audit.o when CONFIG_AUDIT is set.
> 

CONFIG_AUDIT and CONFIG_SECURITY are independent of each other.
With CONFIG_SECURITY=n and CONFIG_AUDIT=y, we now get:

Error log:
arm-linux-gnueabi-ld: security/lsm_audit.o: in function `audit_log_lsm_data':
security/lsm_audit.c:417:(.text+0x5e4): undefined reference to `lockdown_reasons'
arm-linux-gnueabi-ld: security/lsm_audit.c:417:(.text+0x5e8): undefined reference to `lockdown_reasons'
make[3]: *** [scripts/Makefile.vmlinux:78: vmlinux] Error 1
make[2]: *** [Makefile:1178: vmlinux] Error 2
make[1]: *** [Makefile:224: __sub-make] Error 2
make: *** [Makefile:224: __sub-make] Error 2

Guenter