diff options
| -rw-r--r-- | Documentation/module-signing.txt | 31 | ||||
| -rw-r--r-- | Makefile | 2 | ||||
| -rw-r--r-- | init/Kconfig | 14 | ||||
| -rw-r--r-- | kernel/Makefile | 5 |
4 files changed, 46 insertions, 6 deletions
diff --git a/Documentation/module-signing.txt b/Documentation/module-signing.txt index faaa6ea002f7..84597c7ea175 100644 --- a/Documentation/module-signing.txt +++ b/Documentation/module-signing.txt @@ -88,6 +88,22 @@ This has a number of options available: than being a module) so that modules signed with that algorithm can have their signatures checked without causing a dependency loop. + (4) "File name or PKCS#11 URI of module signing key" (CONFIG_MODULE_SIG_KEY) + + Setting this option to something other than its default of + "signing_key.priv" will disable the autogeneration of signing keys and + allow the kernel modules to be signed with a key of your choosing. + The string provided should identify a file containing a private key + in PEM form, or — on systems where the OpenSSL ENGINE_pkcs11 is + appropriately installed — a PKCS#11 URI as defined by RFC7512. + + If the PEM file containing the private key is encrypted, or if the + PKCS#11 token requries a PIN, this can be provided at build time by + means of the KBUILD_SIGN_PIN variable. + + The corresponding X.509 certificate in DER form should still be placed + in a file named signing_key.x509 in the top-level build directory. + ======================= GENERATING SIGNING KEYS @@ -100,8 +116,9 @@ it can be deleted or stored securely. The public key gets built into the kernel so that it can be used to check the signatures as the modules are loaded. -Under normal conditions, the kernel build will automatically generate a new -keypair using openssl if one does not exist in the files: +Under normal conditions, when CONFIG_MODULE_SIG_KEY is unchanged from its +default of "signing_key.priv", the kernel build will automatically generate +a new keypair using openssl if one does not exist in the files: signing_key.priv signing_key.x509 @@ -135,8 +152,12 @@ kernel sources tree and the openssl command. The following is an example to generate the public/private key files: openssl req -new -nodes -utf8 -sha256 -days 36500 -batch -x509 \ - -config x509.genkey -outform DER -out signing_key.x509 \ - -keyout signing_key.priv + -config x509.genkey -outform PEM -out kernel_key.pem \ + -keyout kernel_key.pem + +The full pathname for the resulting kernel_key.pem file can then be specified +in the CONFIG_MODULE_SIG_KEY option, and the certificate and key therein will +be used instead of an autogenerated keypair. ========================= @@ -181,7 +202,7 @@ To manually sign a module, use the scripts/sign-file tool available in the Linux kernel source tree. The script requires 4 arguments: 1. The hash algorithm (e.g., sha256) - 2. The private key filename + 2. The private key filename or PKCS#11 URI 3. The public key filename 4. The kernel module to be signed @@ -870,7 +870,7 @@ INITRD_COMPRESS-$(CONFIG_RD_LZ4) := lz4 # export INITRD_COMPRESS := $(INITRD_COMPRESS-y) ifdef CONFIG_MODULE_SIG_ALL -MODSECKEY = ./signing_key.priv +MODSECKEY = $(CONFIG_MODULE_SIG_KEY) MODPUBKEY = ./signing_key.x509 export MODPUBKEY mod_sign_cmd = scripts/sign-file $(CONFIG_MODULE_SIG_HASH) $(MODSECKEY) $(MODPUBKEY) diff --git a/init/Kconfig b/init/Kconfig index 14b3d8422502..1b1148e9181b 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1948,6 +1948,20 @@ config MODULE_SIG_HASH default "sha384" if MODULE_SIG_SHA384 default "sha512" if MODULE_SIG_SHA512 +config MODULE_SIG_KEY + string "File name or PKCS#11 URI of module signing key" + default "signing_key.priv" + depends on MODULE_SIG + help + Provide the file name of a private key in PKCS#8 PEM format, or + a PKCS#11 URI according to RFC7512. The corresponding X.509 + certificate in DER form should be present in signing_key.x509 + in the top-level build directory. + + If this option is unchanged from its default "signing_key.priv", + then the kernel will automatically generate the private key and + certificate as described in Documentation/module-signing.txt + config MODULE_COMPRESS bool "Compress modules on installation" depends on MODULES diff --git a/kernel/Makefile b/kernel/Makefile index 43c4c920f30a..2c937ace292e 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -170,6 +170,10 @@ ifndef CONFIG_MODULE_SIG_HASH $(error Could not determine digest type to use from kernel config) endif +# We do it this way rather than having a boolean option for enabling an +# external private key, because 'make randconfig' might enable such a +# boolean option and we unfortunately can't make it depend on !RANDCONFIG. +ifeq ($(CONFIG_MODULE_SIG_KEY),"signing_key.priv") signing_key.priv signing_key.x509: x509.genkey @echo "###" @echo "### Now generating an X.509 key pair to be used for signing modules." @@ -207,3 +211,4 @@ x509.genkey: @echo >>x509.genkey "subjectKeyIdentifier=hash" @echo >>x509.genkey "authorityKeyIdentifier=keyid" endif +endif |