Certificates being loaded onto the IMA trusted keyring must be signed by a key on either the builtin and secondary trusted keyring. This patch creates and includes in the kernel image an ephemeral CA key, at build time when IMA_APPRAISE_MODSIG is enabled. Signed-off-by: Nayna Jain <nayna@xxxxxxxxxxxxx> --- Makefile | 2 ++ certs/Makefile | 68 ++++++++++++++++++++++++++++++++++--- certs/system_certificates.S | 16 ++++++++- 3 files changed, 80 insertions(+), 6 deletions(-) diff --git a/Makefile b/Makefile index 9c87fdd600d8..a1d4b0a1745e 100644 --- a/Makefile +++ b/Makefile @@ -1475,6 +1475,8 @@ MRPROPER_FILES += include/config include/generated \ certs/signing_key.pem certs/signing_key.x509 \ certs/x509.genkey certs/signing_key.key \ certs/signing_key.crt certs/signing_key.csr \ + certs/ca_signing_key.pem certs/ca_signing_key.x509 \ + certs/ca_signing_key.srl \ vmlinux-gdb.py \ *.spec diff --git a/certs/Makefile b/certs/Makefile index b2be7eb413d3..c3592ba63a05 100644 --- a/certs/Makefile +++ b/certs/Makefile @@ -32,6 +32,14 @@ endif # CONFIG_SYSTEM_TRUSTED_KEYRING clean-files := x509_certificate_list .x509.list ifeq ($(CONFIG_MODULE_SIG),y) +SIGN_KEY = y +endif + +ifeq ($(CONFIG_IMA_APPRAISE_MODSIG),y) +SIGN_KEY = y +endif + +ifdef SIGN_KEY ############################################################################### # # If module signing is requested, say by allyesconfig, but a key has not been @@ -51,6 +59,16 @@ silent_redirect_openssl = 2>/dev/null # external private key, because 'make randconfig' might enable such a # boolean option and we unfortunately can't make it depend on !RANDCONFIG. ifeq ($(CONFIG_MODULE_SIG_KEY),"certs/signing_key.pem") + +ifeq ($(CONFIG_IMA_APPRAISE_MODSIG),y) +# openssl arguments for CA Signed certificate. +CA_KEY = certs/ca_signing_key.pem +SIGNER = -CA $(CA_KEY) -CAkey $(CA_KEY) -CAcreateserial +else +# openssl arguments for Self Signed certificate. +SIGNER = -signkey $(obj)/signing_key.key +endif # CONFIG_IMA_APPRAISE_MODSIG + $(obj)/signing_key.pem: $(obj)/x509.genkey @$(kecho) "###" @$(kecho) "### Now generating an X.509 key pair to be used for signing modules." @@ -60,14 +78,23 @@ $(obj)/signing_key.pem: $(obj)/x509.genkey @$(kecho) "### needs to be run as root, and uses a hardware random" @$(kecho) "### number generator if one is available." @$(kecho) "###" +ifeq ($(CONFIG_IMA_APPRAISE_MODSIG),y) + # Generate kernel build time CA Certificate. + @$(Q)openssl req -new -nodes -utf8 \ + -$(CONFIG_MODULE_SIG_HASH) -days 36500 \ + -subj "/CN=Build time autogenerated kernel CA key" \ + -batch -x509 -config $(obj)/x509.genkey \ + -outform PEM -out $(CA_KEY) \ + -keyout $(CA_KEY) -extensions ca_ext \ + $($(quiet)redirect_openssl) +endif # CONFIG_IMA_APPRAISE_MODSIG $(Q)openssl req -new -nodes -utf8 \ -batch -config $(obj)/x509.genkey \ -outform PEM -out $(obj)/signing_key.csr \ -keyout $(obj)/signing_key.key -extensions myexts \ $($(quiet)redirect_openssl) $(Q)openssl x509 -req -days 36500 -in $(obj)/signing_key.csr \ - -outform PEM -out $(obj)/signing_key.crt \ - -signkey $(obj)/signing_key.key \ + -outform PEM -out $(obj)/signing_key.crt $(SIGNER) \ -$(CONFIG_MODULE_SIG_HASH) -extensions myexts \ -extfile $(obj)/x509.genkey \ $($(quiet)redirect_openssl) @@ -95,19 +122,50 @@ $(obj)/x509.genkey: @echo >>$@ "keyUsage=digitalSignature" @echo >>$@ "subjectKeyIdentifier=hash" @echo >>$@ "authorityKeyIdentifier=keyid" + @echo >>$@ + @echo >>$@ "[ ca_ext ]" + @echo >>$@ "keyUsage=critical,keyCertSign" + @echo >>$@ "basicConstraints=critical,CA:TRUE,pathlen:0" + @echo >>$@ "subjectKeyIdentifier=hash" + @echo >>$@ "authorityKeyIdentifier=keyid" endif # CONFIG_MODULE_SIG_KEY $(eval $(call config_filename,MODULE_SIG_KEY)) +SUBJECT=CN = Build time autogenerated kernel key +ISSUER=$(shell openssl x509 -in certs/signing_key.crt -noout -issuer) # If CONFIG_MODULE_SIG_KEY isn't a PKCS#11 URI, depend on it + +# GCC PR#66871 again. +ifeq ($(CONFIG_IMA_APPRAISE_MODSIG),y) + +# Remove existing keys if it is self-signed. +$(if $(findstring $(SUBJECT),$(ISSUER)),$(shell rm -f certs/signing_key.* certs/x509.genkey)) +CA_KEY = certs/ca_signing_key.pem + +$(obj)/system_certificates.o: $(obj)/ca_signing_key.x509 $(obj)/signing_key.x509 + +targets += ca_signing_key.x509 +$(obj)/ca_signing_key.x509: $(obj)/signing_key.x509 scripts/extract-cert FORCE + $(call if_changed,extract_certs,$(CA_KEY)) + +targets += signing_key.x509 +$(obj)/signing_key.x509: $(obj)/signing_key.pem scripts/extract-cert FORCE + $(call if_changed,extract_certs,$(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY)) +else + +# Remove existing keys if it is CA signed. +$(if $(findstring $(SUBJECT),$(ISSUER)),,$(shell rm -f certs/ca_signing_key.* certs/signing_key.* certs/x509.genkey)) + ifeq ($(patsubst pkcs11:%,%,$(firstword $(MODULE_SIG_KEY_FILENAME))),$(firstword $(MODULE_SIG_KEY_FILENAME))) X509_DEP := $(MODULE_SIG_KEY_SRCPREFIX)$(MODULE_SIG_KEY_FILENAME) endif -# GCC PR#66871 again. $(obj)/system_certificates.o: $(obj)/signing_key.x509 targets += signing_key.x509 -$(obj)/signing_key.x509: scripts/extract-cert $(X509_DEP) FORCE +$(obj)/signing_key.x509: certs/signing_key.pem scripts/extract-cert $(X509_DEP) FORCE $(call if_changed,extract_certs,$(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY)) -endif # CONFIG_MODULE_SIG + +endif # CONFIG_IMA_APPRAISE_MODSIG +endif # SIGN_KEY diff --git a/certs/system_certificates.S b/certs/system_certificates.S index 8f29058adf93..e10043800a7e 100644 --- a/certs/system_certificates.S +++ b/certs/system_certificates.S @@ -8,8 +8,13 @@ .globl system_certificate_list system_certificate_list: __cert_list_start: -#ifdef CONFIG_MODULE_SIG +__module_cert_start: +#if defined(CONFIG_MODULE_SIG) || defined(CONFIG_IMA_APPRAISE_MODSIG) .incbin "certs/signing_key.x509" +#endif +__module_cert_end: +#ifdef CONFIG_IMA_APPRAISE_MODSIG + .incbin "certs/ca_signing_key.x509" #endif .incbin "certs/x509_certificate_list" __cert_list_end: @@ -35,3 +40,12 @@ system_certificate_list_size: #else .long __cert_list_end - __cert_list_start #endif + + .align 8 + .globl module_cert_size + module_cert_size: +#ifdef CONFIG_64BIT + .quad __module_cert_end - __module_cert_start +#else + .long __module_cert_end - __module_cert_start +#endif -- 2.18.1
