diff mbox series

[kvm-unit-tests,v3,2/2] s390x: create persistent comm-key

Message ID 20220909121453.202548-3-nrb@linux.ibm.com (mailing list archive)
State Mainlined
Headers show
Series s390x: dump support for PV tests | expand

Commit Message

Nico Boehr Sept. 9, 2022, 12:14 p.m. UTC
To decrypt the dump of a PV guest, the comm-key (CCK) is required. Until
now, no comm-key was provided to genprotimg, therefore decrypting the
dump of a kvm-unit-test under PV was not possible.

This patch makes sure that we create a random CCK if there's no
$(TEST_DIR)/comm.key file.

Also allow dumping of PV tests by passing the appropriate PCF to
genprotimg (bit 34). --x-pcf is used to be compatible with older
genprotimg versions, which don't support --enable-dump. 0xe0 is the
default PCF value and only bit 34 is added.

Unfortunately, recent versions of genprotimg removed the --x-comm-key
argument which was used by older versions to specify the CCK. To support
these versions, we need to parse the genprotimg help output and decide
which argument to use.

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
---
 s390x/Makefile | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

Comments

Janosch Frank Sept. 13, 2022, 12:36 p.m. UTC | #1
On 9/9/22 14:14, Nico Boehr wrote:
> To decrypt the dump of a PV guest, the comm-key (CCK) is required. Until
> now, no comm-key was provided to genprotimg, therefore decrypting the
> dump of a kvm-unit-test under PV was not possible.
> 
> This patch makes sure that we create a random CCK if there's no
> $(TEST_DIR)/comm.key file.
> 
> Also allow dumping of PV tests by passing the appropriate PCF to
> genprotimg (bit 34). --x-pcf is used to be compatible with older
> genprotimg versions, which don't support --enable-dump. 0xe0 is the
> default PCF value and only bit 34 is added.
> 
> Unfortunately, recent versions of genprotimg removed the --x-comm-key
> argument which was used by older versions to specify the CCK. To support
> these versions, we need to parse the genprotimg help output and decide
> which argument to use.
> 
> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
diff mbox series

Patch

diff --git a/s390x/Makefile b/s390x/Makefile
index d17055ebe6a8..d1a7bf6004a1 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -162,15 +162,33 @@  $(SNIPPET_DIR)/c/%.hdr: $(SNIPPET_DIR)/c/%.gbin $(HOST_KEY_DOCUMENT)
 	$(RM) $(@:.elf=.aux.o)
 	@chmod a-x $@
 
+# Secure Execution Customer Communication Key file
+# 32 bytes of key material, uses existing one if available
+comm-key = $(TEST_DIR)/comm.key
+$(comm-key):
+	dd if=/dev/urandom of=$@ bs=32 count=1 status=none
+
 %.bin: %.elf
 	$(OBJCOPY) -O binary  $< $@
 
-genprotimg_args = --host-key-document $(HOST_KEY_DOCUMENT) --no-verify
+# The genprotimg arguments for the cck changed over time so we need to
+# figure out which argument to use in order to set the cck
+GENPROTIMG_HAS_COMM_KEY = $(shell $(GENPROTIMG) --help | grep -q -- --comm-key && echo yes)
+ifeq ($(GENPROTIMG_HAS_COMM_KEY),yes)
+	GENPROTIMG_COMM_KEY = --comm-key $(comm-key)
+else
+	GENPROTIMG_COMM_KEY = --x-comm-key $(comm-key)
+endif
+
+# use x-pcf to be compatible with old genprotimg versions
+# allow dumping + PCKMO
+genprotimg_pcf = 0x200000e0
+genprotimg_args = --host-key-document $(HOST_KEY_DOCUMENT) --no-verify $(GENPROTIMG_COMM_KEY) --x-pcf $(genprotimg_pcf)
 
-%selftest.pv.bin: %selftest.bin $(HOST_KEY_DOCUMENT) $(patsubst %.pv.bin,%.parmfile,$@)
+%selftest.pv.bin: %selftest.bin $(HOST_KEY_DOCUMENT) $(patsubst %.pv.bin,%.parmfile,$@) $(comm-key)
 	$(GENPROTIMG) $(genprotimg_args) --parmfile $(patsubst %.pv.bin,%.parmfile,$@) --image $< -o $@
 
-%.pv.bin: %.bin $(HOST_KEY_DOCUMENT)
+%.pv.bin: %.bin $(HOST_KEY_DOCUMENT) $(comm-key)
 	$(GENPROTIMG) $(genprotimg_args) --image $< -o $@
 
 $(snippet_asmlib): $$(patsubst %.o,%.S,$$@) $(asm-offsets)
@@ -178,7 +196,7 @@  $(snippet_asmlib): $$(patsubst %.o,%.S,$$@) $(asm-offsets)
 
 
 arch_clean: asm_offsets_clean
-	$(RM) $(TEST_DIR)/*.{o,elf,bin} $(SNIPPET_DIR)/*/*.{o,elf,*bin,*obj,hdr} $(SNIPPET_DIR)/asm/.*.d $(TEST_DIR)/.*.d lib/s390x/.*.d
+	$(RM) $(TEST_DIR)/*.{o,elf,bin} $(SNIPPET_DIR)/*/*.{o,elf,*bin,*obj,hdr} $(SNIPPET_DIR)/asm/.*.d $(TEST_DIR)/.*.d lib/s390x/.*.d $(comm-key)
 
 generated-files = $(asm-offsets)
 $(tests:.elf=.o) $(asmlib) $(cflatobjs): $(generated-files)