[PATCH] ipe: Search for the boot policy file in the source tree

[Tyler Hicks]

Resolve CONFIG_IPE_BOOT_POLICY relative file paths in the source tree if
the file was not found within the object tree and is not an absolute path.

This fixes an IPE build failure that occurs when using an output directory,
such as with the `O=/tmp/build` make option, during a build with the
CONFIG_IPE_BOOT_POLICY option set to a path that's relative to the kernel
source tree. For example,

  $ grep CONFIG_IPE_BOOT_POLICY /tmp/build/.config
  CONFIG_IPE_BOOT_POLICY="ipe-boot-policy"
  $ touch ipe-boot-policy
  $ make O=/tmp/build
  make[1]: Entering directory '/tmp/build'
    GEN     Makefile
    UPD     include/config/kernel.release
    UPD     include/generated/utsrelease.h
    CALL    scripts/checksyscalls.sh
    CC      init/version.o
    AR      init/built-in.a
    CC      kernel/sys.o
    AR      kernel/built-in.a
    IPE_POL ipe-boot-policy
  An error occurred during policy conversion: : No such file or directory
  make[5]: *** [security/ipe/Makefile:14: security/ipe/boot_policy.c] Error 2
  make[4]: *** [scripts/Makefile.build:440: security/ipe] Error 2
  make[3]: *** [scripts/Makefile.build:440: security] Error 2
  make[2]: *** [Makefile:1989: .] Error 2
  make[1]: *** [Makefile:251: __sub-make] Error 2
  make[1]: Leaving directory '/tmp/build'
  make: *** [Makefile:251: __sub-make] Error 2

Fixes: ba199dc909a2 ("scripts: add boot policy generation program")
Cc: stable at vger.kernel.org
Signed-off-by: Tyler Hicks <code at tyhicks.com>
---
 security/ipe/Makefile | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/security/ipe/Makefile b/security/ipe/Makefile
index 2ffabfa63fe9..b54d7b7c9e6d 100644
--- a/security/ipe/Makefile
+++ b/security/ipe/Makefile
@@ -10,8 +10,10 @@ quiet_cmd_polgen = IPE_POL $(2)
 
 targets += boot_policy.c
 
-$(obj)/boot_policy.c: scripts/ipe/polgen/polgen $(CONFIG_IPE_BOOT_POLICY) FORCE
-	$(call if_changed,polgen,$(CONFIG_IPE_BOOT_POLICY))
+boot-pol := $(if $(wildcard $(CONFIG_IPE_BOOT_POLICY)),,$(srctree)/)$(CONFIG_IPE_BOOT_POLICY)
+
+$(obj)/boot_policy.c: scripts/ipe/polgen/polgen $(boot-pol) FORCE
+	$(call if_changed,polgen,$(boot-pol))
 
 obj-$(CONFIG_SECURITY_IPE) += \
 	boot_policy.o \
-- 
2.34.1